MICROORGANISMS IN A FLUID SAMPLE

CROSS-REFERENCE TO RELATED APPLICATIONS £0001 1 This application claims the benefit of U.S. Provisional Patent Application Number 62/209,754 filed on August 25, 2015, the content of which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

|0002| The present disclosure relates generally to in vitro detection of microorganisms and, more specifically, to devices, systems, and methods for detecting viable

microorganisms in a fluid sample.

BACKGROUND

0003 infections caused by anti-infective resistant microorganisms or microbes are a significant problem for healthcare professionals in hospitals, nursing homes, and other healthcare environments. For example, such infections can lead to a potentially life- threatening complication known as sepsis where chemicals released into the bloodstream by a microorganism can trigger a dangerous whole-body inflammatory response as well as a vasoactive response causing fever, low blood, pressure, and possibly death. When faced with such an infection, a preferred course of action is for a clinician to use anti-infective compounds judiciously, preferably onl those necessary to alleviate the infection.

However, what occurs most frequently today is that until the organism is identified and tested for drug sensitivity, broad spectrum antt-infceiives, of¾eu multiple drugs, are given to the patient to insure adequacy of treatment This tends to result in multiple drug resistant microorganisms. Ideally, the sensitivity of the microorganism would be detected soon after its presence is identified. The present disclosure presents devices, systems, and methods for accomplishing this goal.

[0004| Existing methods and instruments used to detect anti-infective resistance in microorganisms include costly and labor intensive microbial culturing techniques to isolate the microorganism and include tests such as agar disk diffusion or broth mierodiiution where a ti-infcctives are introduced as liquid suspensions, paper disks, or dried gradients on agar media. However, those methods require manual interpretation by skilled personnel and are prone to technical or clinician error.

jOOOSj While automated inspection of such panels or media can reduce the likelihood, of clinician error, current instruments used to conduc t these inspections are often costly and require constant maintenance, in addition, current instruments often rely on an optica! readout of the investigated samples requiring bulky detection equipment and access to power supplies. Most importantly, these methods require days to obtain a result, as the microorganisms must reproduce several times in different media prior to being exposed to the anti-infective to determine their susceptibility.

{0006 j In addition, such methods and instruments often cannot conduct such tests directly on a patient's bodily fluids and require length sample preparation times.

[0007] As a result of the above limitations and restrictions, there is a need for improved devices, systems, and methods to quickly and effectively detect anti-infective resistant microorganisms in a patient sample.

SUMMARY

{0008] Various devices, systems and methods for detecting the susceptibility of a microorganism in a patient sample to one or more anti-infectives are described herein. {(KM)9[ in one embodiment, a method for detecting the susceptibility of a

microorganism in a sample to one or more anti-infectives can include

{OOIOJ In one embodiment, a method for detec ting the susceptibility of a

microorganism in a sample to one or more anti-infectives can include introducing the sample to a surface, such as a filter surface or a substrate surface. The method can also include exposing the microoraanism to a first solution. The method can further include monitoring an electrical characteristic of a sensor upon separating the first solution from the microorganism and then introducing the first solution to the sensor. The method can also include exposing the surface comprising the microorganism with a. second solution, wherein the second solution comprises an anti-infective. The method can further include separating the second solution from the microorganism after exposing the surface. The method can also include detecting any changes in the electrical characteristic of the sensor after introducing the second solution to the sensor. The method can further include assessing the susceptibilit of the microorganism to the anti-infective using any detected changes in the electrical characteristic of the sensor.

jOOl lJ The method can further include monitoring a first electrical characteristic of a first sensor, such as a control sensor, upon introducing the first solution to the first sensor, [0012] In a further embodiment, the method for detecting an anti-infective to which the microorganism is susceptible can include exposing a filter surface or a substrate surface comprising a microorganism with a first solution, such as a nutrient solution. The method can also include incubating the filter comprising the microorganism and the first solution. The method can aiso include separating the first solution from the microorganism after incubating the filter. The method can. also include monitoring a first solution characteristic of the first solution using a sensor or a sensor device, such as an ISFET sensor. The method can also include exposing the filter comprising the microorganism with a second solution, wherein the second solution comprises an ami -infective. The method can also include incubating the filter comprising the microorganism and the second solution. The method can also include separating the second solution from the microorganism after incubating the fi lter. The method can also include monitoring a second solution characteristic of the second solution using the sensor. The method can further include comparing the first solution: characteristic and the second solution, characteristic to assess the susceptibility of the microorganism to the anti-infective,

[0013] in yet another embodiment, the method for detecting an anti -infective resistant microorganism in a fluid sample can include temporarily exposing a solution, such as a nutrient solution, to a microorganism, wherein the solution comprises an anti -infective. The method can also include providing a sensor in fluid communication with the solution after the solution is separated from the microorganism, wherein the sensor can comprise an electrical characteristic. The method can also include monitoring the sensor for a change to the electrical characteristic of the sensor after providing the sensor in fluid communication with the solution. The method can also include pro viding an indication of the susceptibility of the microorganism to the anti-infective upon a failure to detect the change to the electrical characteristic of the sensor.

f00I4| In another embodiment, the method for detecting a susceptibility of a microorganism to an anti-infective can include delivering a first solution to a surface, such as a filter surface or a substrate s aface. The first solution can be free of the anti-infective and a .microorganism can be located on the surface. The method can also include separating the first solution from the microorganism and the surface. The method can further include iliadly coupling a sensor with the first solution. The method can also include monitoring an electrical characteristic of the sensor while the sensor is . urdly coupled to the first solution. The method can further include delivering a second solution to the surface, where the second solution comprises the anti-infecti ve. The method can also include separating the second solution from the microorganism and the surface. The method can further include monitoring the sensor for a change in the electrical characteristic while the sensor is flnidiy coupled to the second solution to assess the susceptibil ity of the microorganism to the anti- infective.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 00J5| Fig. 1 illustrates one embodiment of a system for detecting anti-infective susceptible microorganisms,

|0016j Fig. 2 illustrates another embodiment of the system for detecting anti-infective snscepti ble microorganisms .

j¾01?| Fig. 3 illustrates another embodiment of the system for detecting anti-infective susceptible microorganisms.

|0018| Fig. 4A illustrates a side view of an embodiment of a substrate having an active sensor disposed on the substrate and an external reference.

f0019{ Fig. 4B illustrates a side vie of an embodiment of a substrate having the active sensor and an on-chip reference electrode disposed on the substrate.

[0020] Fig. 5 A illustrates a side view of an embodiment of a substrate having the active sensor and a control sensor disposed on the substrate and an external reference electrode.

10021 Fig. 5B illustrates a side view of an embodiment of a substrate having the active sensor, the control sensor, and the on-chip reference electrode disposed on the substrate.

|0022| Fig. 6A illustrates a side view of an embodiment of the active sensor and the control sensor each having an extended gate and an external reference electrode.

{6023 J Fig. 6S illustrates a side view of an embodiment of the active sensor and the control sensor each having an extended gate and an on-chip reference electrode.

|f)024{ Pig. 7 illustrates an embodiment of the system on a disposable strip.

[0025| Fig. 8 illustrates the analyzer and the reader processing signals outpuited by the active sensor and the control sensor. |Θ026| Fig. 9 illustrates experimental results of experiments conduc ted using the methods and systems described herein.

[6027] Fig. 1 illustrates additional experimental results of experiments conducted using the methods and systems described herein.

[0028] Fig. 1 1 illustrates an embodiment of a method for detecting a susceptibility of a microorganism to one or more anti-infectives.

[0 2 1 Fig. 12 illustrates another embodiment of the method for detecting a susceptibility of a microorganism to one or more anti-infectives.

[0030[ Fig. 13 illustrates yet another embodiment of the method for detecting a susceptibility of a. microorganism to one or more anti-infectives.

[0031] Fig. 14 illustrates another embodiment of the method for detecting a susceptibility of a microorganism to one or more anti-infectives.

[0032] Fig. 1 5 illustrates a further embodiment of the method for detecting a susceptibility of a microorganism to one or more anti-infectives,

[00331 Fig. 16 illustrates another embodiment of the method for detecting

susceptibility of a microorganism to one or more ami- infectives.

DETAILED DESCRIPTION

[0O34J Variations of the devices, systems, and methods described herein are best understood from the detailed description when read in conjunction with the accompanying drawings, it is emphasized that, according to common practice , the various features of the drawings may not be to scale. On the contrary, the dimensions of the various features may be arbiixariiv expanded or reduced for clarity and not all features ma be visibie or labeled in every drawing. The drawings are taken for illustrative purposes only and are not intended to define or limit the scope of the claims to that which is shown.

[0035| Figure 1 illustrates an embodiment of a system 100 for detecting or assessing a susceptibility of a microorganism 102 to an anti-infective 104. The system 100 can comprise a fluid deliver}' device 1 6, a filter housing 108 containing a filter 110, a substrate 112, and a reader 114. The substrate 1 12 can have one or more sensors 1 16 disposed on a surface of the substrate 112. The substrate 1 12 can be comprised of a polymeric material a metal, a ceramic, a semiconductor layer, an oxide layer, an insulator, or a combination thereof. The system 100 can also include an analyzer 1 1 . In the embodiment shown in Figure ! , the analyzer i 18 can be disposed on a surface of the substrate 112. 1» other embodiments, the analyzer 1 IB can be a standalone unit or device coupled to the substrate 1 12.

j0036| The sensors 1 16 can include one or more active sensors 120, one or more control sensors 122, or a combination thereof. As illustrated irt the embodiment shown in Figure 1, the one or more active sensors 120 and control sensors 122 can be disposed on the same side surface of the substrate 1 12. in other embodiments not shown in Figure 1 , th active sensors 120 and the control sensors 122 can be disposed ort different surfaces of the substrate 1 .1 2, different substrates 1 12, or a combination thereof. For example. Figure 1 shows the substrate 1 I 2 having four sensors 116; however, it is contemplated that the substrate 112 can comprise any number of sensors 116. In one embodiment, at least one of the sensors 116 can be an ion-sensitive field effect transistor (ISFET). The sensors 1 16 will be discussed in more detail in the sections thai follow.

f0037J The system 100 can detect or assess the level of susceptibility of the microorganism 102 to an anti-infective 104 when the microorganism 102 is in a fluid sample .124. The fluid sample 124 can include a bodily fluid such as blood, serum, plasma, urine, saliva, joint fluid, semen, wound material, spina! fluid, mucus, or a combination thereof. In other embodiments, the fluid sample 124 can also include an environmental fluid such as liquids sampled from a stream, river, lake, ocean, contamination site, quarantine zone, or emergency area. The fluid sample 1 4 can also be a food sample,

[0038| The microorganism 102 can be any metabolizing single or multi-cellular organism including bacteria or fungi, in certain embodiments, the microorganism 102 can be a bacteria selected from the genera consisting of Acinetobacter, Aeromonas, Bacillus, Racieroid.es, Citrobacter, Enterobaeter, Escherichia, Klebsiella, Morganella, Pandoraea, Proteus, Provkle cia, Pseudomonas, Raistonia, Raoultella, Salmonella, Serraiia,

She anel ^' ia, Shigella, Stenofrophomonas, Streptomyces, Staphylococcus, Enteroeoeeus, Clostridium or an combination thereof. In other embodiments, the microorganism 102 can be a fungi selected from the genera consisting of Candi da, Cryptococcus, or an

combination thereof. In another embodiment, the microorganism 102 can include amoeba. In further embodiments, the microorganism 102 can be cancer cells and the anti-infecti ves 104 can be chemotherapeutics or other cancer treatments.

|603*>J As illustrated in Figure 1 , the fluid delivery device 1 6 can deliver or inject the fluid sample 124 comprising the microorganism 1 2 into the filter housing 108 in step 1A. In the example embodiment shown in Figure .1 , the fluid delivery device 106 can be a syringe. In other embodiments not shown in Figure I , the fluid delivery device 1 6 can be an injection cartridge, a microfiuidic channel, a pipette, a reaction tube, a capillary, a test tube, a combination thereof or a portion therein.

j0040| The filter housing 1 8 can be a container or vessel configured to secure or enclose the filter 110. For example, the filter housing .108 can be a housing of a syringe filter. The filter 1 10 can be a mesh or matrix for isolating or separating the microorganism 102 or other molecules or cells from the supernatant of the fluid sample 124. in certain embodiments, the filter .1 10 can be selected from the group consisting of cellulose acetate, regenerated cellulose, nylon, polystyrene, poJyvmylidene fluoride (PVDP),

polyethersulfone (PES), polytetrafluorethylene (PTFE), or a combination thereof

|0041| The filter 110 can comprise a filter surface 126. The filter surface 126 can be the portion of the filter 110 used to isolate or trap the microorganism 102. The filter surface .126 can include an external surface, an internal surface extending into the filter 110, or a combination thereof ^" . The filter housing 108 can have at least one opening 128 which allow fluid or supernatant from the fluid sample 124 to evacuate the filter housing 108. For example, step 1 A can include the additional step of discarding the fluid or supernatant from the fluid sample 124 through the opening 128 after isolating the microorganism 1 2 on the filter surface 126,

|0042| In an alternative embodiment not shown in Figure I, the fluid sample 1.24 can be pre-filtered in a step before step 1 A, This pre-filteriog step can involve filtering the fluid sample 124 using another instance of the fitter 1 10, a microfiuidic filter, or a combination thereof to filter out other larger eei.lui.ar components including blood cells or epithelial ceils from the fluid sample 124 when, the fluid sample 124 is composed of bodily fluid, f 00431 The same fluid delivery device 106 or another fluid delivers' device .106 can also be used to deliver or inject a nutrient solution 130 to the filter housing 108 in step IB. The fluid delivery device 1 6 can continuously or periodically expose the filter surface 1.26 containing the microorganism 1 2 with the nutrient solution .130. in one embodiment, the nutrient solution 130 can be composed of a buffer containing bacto-trypt ne, yeast extract, sodium chloride and any combinations thereof. Jn another embodiment the nutrient solution can include a growth inducer. ^' The growth inducer can be selected from the group consisting of a carbon-based inducer, a nitrogen-based inducer, a mineral, a trace element, a biological growth factor, or any combination thereof. For example, the growth inducer can include but is not limited to glucose, ammonia, magnesium, or a combination thereof. For example, the nutrient solution. 130 can be O.Lx Luria Broth supplemented, with 100 mM glucose. |0044{ The buffer io the nutrient solution 130 can be an acidic buffer or a basic buffer. The ^' buffer cao be used to counteract the ^' buffering effects of tons or substances present the fluid sample 124 when the fluid sample Ϊ 24 is composed of a bodily fluid.

[0045] The filter 110 comprising the microorganism 102 can be heated to a temperature of between 30 "C and 40 "C and allowed to incubate for an incubation period 132 in step 1 C. In one embodiment, the filter 110 can be incubated while in the filter housing 108. in another embodiment the filter 1.10 can be removed from the filter housing 1 OS prior to incubation. In some embodiments, the filter 110 can be incubated with the nutrient solution 1.30. The incubation period 132 can range from 15 minutes to over one hour, in other embodiments, the incubation period 132 can be less than. 15 minutes. The incubation, period 132 can be adjusted based on the type of microorganism 102, such as the type of bacteria or fungi.

|¾046] The incubation period 132. can also be adjusted based on the amount of the microorganism 102 present in the fluid sample 124. For example, the incubation period 132 can be increased when the amount of the microorganism 1 2 is below a threshold amount. The filter ! 10 can be allowed to incubate with the nutrient solution 130 in order to promote the proliferation of the microorganism 102 on the filter surface 126. One advantage of incubating the filter 1.10 is to increase the sensitivity of the system. 100 to small amounts of the microorganism 1 2, For example, incubating the filter 110 can allow the system 100 to reduce its level of detection, in one embodiment, the system 100 can detect as few as 500 bacteria per milliliter. In other embodiments, the system 100 can detect fewer than .500 bacteria per milliliter. In further embodiments, the system 100 can detect l* ^" 10 ⁴ bacteria per milliliter.

|0O47{ After incubating the filter 1 10, the same fluid delivery device 1 6 or another fluid delivery device 106 can then be used to expose the filter surface 126 with additional nutrient solution 130 in step ID. One advantage of exposing the filter 1 .1 with the additional nutrient solution 130 is to prevent the filter housing 108, the filter 1 10, or the environment housing the microorganism 102 from becoming overly acidified as result, of cellular acti vity, cellular metabolism, or growth undertaken by the microorganism ^" 102. For example, the filter housing 108 or the filter 110 comprising the microorganism 1 2 can become overly acidified as result of the microorganism 102 undergoing cellular metabolism, or growth,

(00 81 As illustrated in the example embodiment shown in. Figure 1, the effluent or outflow from the exposure step of step ID can be Introduced or applied to one or more of the sensors 1 16 disposed on the substrate 1 1 . This effluent or outflow can be referred to as a sample effluent 134.

|0049| The sample effluent 134 can be introduced to one or more of the sensors ί 1 disposed on the substrate 1 12 through the opening 128 in the filter housing 108. The opening 128 can include a channel, a capillary, a tube, or a combination thereof. The sample effluent 134 can be separated from the microorganism 1 2 on the filter surface 126 as the sample effluent 134 flows through the filter 1 10 on to the sensors 1 16. In these embodiments, the microorganism 1 2 can be kept separate or prevented from contacting any portion of the sensors 1 1 disposed on the substrate 1 1.2,

jOOSOJ The sample effluent 134 can comprise a solution characteristic 136. The solution characteristic 136 can refer to one or more aitribotes of the solution making up the sample effluent 134. For example, the solution characteristic 136 can include a

concentration of a solute or an absolute number of solutes in solution. The soiutton characteristic 136 can include art amount or concentration of ions, organic molecules such as amino acids, minerals, or other inorganic compounds in the sample effluent 134.

|00511 The solution characteristic 1 6 can vary as a result of ions, organic molecules, or minerals produced by or attribute to the microorganism 102 on the filter surface 126, The solution characteristic 1 6 can be a direct or indirect byproduct of a cellular activity undertaken by the microorganism 102 such as cell metabolism or cell growth. In one embodiment, the sample effluent 134 can comprise hydrogen ions (IT) as a byproduct of bacterial cell metabolism or growth. In other embodiments, the sample effluent 134 can comprise adenosine triphosphate (ATP), carbon dioxide {€(¾), lactic acid, carbonic acid, nitrates (NO;; ^" ), or a combination thereof produced by or attributed to the microorganism 102,

(0052J After introducing the sample effluent 1 4 to the sensors .116, the same fluid delivery device 106 or another fluid delivery device 106 can be used to introduce an anti- infective 104 to the filter surface 126 comprising the microorganism 102 in step I E. in the example embodiment shown in Figure 1 , the anti-infective 1 4 can be mixed with additional nutrient solution 130 and the filte surface 126 comprising the microorganism 102 can be exposed to additional nutrient solution 130. in other embodiments, the anti- infective 104 can be introduced to the filter surface 126 separate from the nutrient solution 130,

{8053J The anti-infective 1 4 can comprise a bacteriostatic anti-infective, a bactericidal anti-infecti ve, or a combination thereof In certain embodiments, the bacteriostatic ami- infective can comprise (Mactaras, Aminoglycosides, Ausamyeius G.tycopcptides,

Lipopeptides, Quin.oIon.es, Streptogrami«s, or any combination, thereof The bactericidal anti-infective can comprise Chloramphenicols, Maerohdes, Q a olidinones, Sulfonamides, Tetracyclines,, any combination thereof or future derivations thereof

|¾054] In the example embodiment shown in Figure i, the fiiter 1 10 incubated in step 1 C can be divided into two separate filters i 1 with each fiiter i 1 having the

microorganism 102 on the filter surface 126. in this embodiment, nutrient solution 130 containing the anti-infecti e 104 can be exposed or introduced to one of the filters 110 comprising the microorganism .102 in step ID and nutrient solution 130 without the anti- infective 104 ca be exposed or introduced to the other fiiter 1 10 in step I E. in one embodiment, step .1 D can occur concurrently or near in time with step IE. I.n other embodiments, step I D and step .1 E can occur sequentially.

[0055] in these embodiments, the sample effluent 134 resulting from the exposure step of step I D can be introduced to a different sensor .11.6 than the sensor 116 used to analyze the sample effluent 134 from step IE. Also, in these embodiments, the sensor .1 16 receiving the sample effluent 134 containing the anti-Infective 104 can be referred to as the active sensor 120 and the sensor 116 receiving the sampie effluent 134 wiihoui: the anti-infective .10 can be referred to as the control sensor 122.

[0056| in an alternative embodiment contemplated by the present disclosure, the same filter 110 exposed to the nutrient solution. 130 in step IE can be exposed to a nutrient solution 130 containing the anti-infective 104 at a later point in time In this embodiment, the sample effluent Ϊ34 from the exposure step comprising the anti-infective 104 can also be introduced to the same sensor i 1 as the sensor 116 used to measure the no.n-anti- tiifeetive sample effluent i 34 in step 1 E.

j0057J In yet another embodiment contemplated but not shown in Figure 1 , portions of the fluid sampie 124 can be divided, into multiple fiiter housing 108 prior to step 1 A. in this embodiment each filter housing 108 can contain a filter 1 10 comprising

microorganisms 102 from the fluid sample 124 disposed o the filter surface .126. Each of the fiiter housings 108 can be incubated and a variety of nutrient solutions 130, including nutrient solutions 130 lacking in anti -infective 104 or containing different types of anti- infectives 104, can be used to expose the various filters 1 10, In this embodiment, the sampie effluent 134 from the various filter housings 108 can be introduced to different sensors 1 16 on the substrate 112. {0058} While Figure 1 illustrates two of the four sensors 116 on the substrate 112 being used to analyze sample effluent 134 from the fluid sample 124 it is contemplated that the substrate 112 caa accommodate any number of sensors Ϊ 16 for receiving the sample effluent 134. For example, the substrate 1 12 can he a support or housing for a high throughput assay plate such as a 96 well plate, a 1 2 well plate, or a 384 well plate. In this example, each of the well plates can be in fluid communication with one or more sensors 1 16. in another embodiment, the sensors 1 1 can be positioned directly underneath fiie filter housing 108.

fO059{ The reader 1 14, the analyzer 1 18, or a combination thereof can be configured to monitor an electrical characteristic 80G (see Fig. 8} of the sensors 1 16 upon introducing the sample effluent 134 to the sensors 1 16. For example, die reader 114 can monitor die electrical characteristic 800 of the sensors 1 16 by recei ving one or more signals from the analyzer 1 1 disposed on the substrate 1 12, In one embodiment, the analyzer 1 18 can comprise a controller to execute logical commands concerning the detection or comparison of the electrical characteristic 800 of the sensors 1 16. In other embodiments, the controller can be integrated with the reader 114 or another device coupled to the analyzer 1 18.

{0060} The electrical characteristic 800 can include a current, a voltage, a threshold voltage, a capacitance, a resistance, a noise level, a subthreshold swing, a level of induction, or a combination thereof measured at or near the sensor 11 , The reader 114 can be electrically or communicatively coupled to the analyzer 118, the substrate 112, or a combination thereof to monitor the electrical characteristic 800 of the sensors 1 .16 over time. The reader 114 can also be configured to provide a read-out of the electrical characteristic 800 of the sensors 1 16.

{0061 { In certain embodiments, the reader 1 14 can be a mobile device, a handheld device, a tablet device, or a computing device such as a laptop or desktop computer. In other embodiments, the reader .1 14, die analyzer 118, a combination thereof, or any portion therein can be integrated into an ISFBT probe or meter,

[0062 j in the example embodiment shown in Figure 1 , the analyzer 1 .1 _; the reader 114, or a combination thereof can monitor the elec trical characterist c 800 of the sensors 116, such as the active sensor 120 and the control sensor 122 in step IF. The analyzer 1 18, the reader 1 14, or a combination thereof can monitor the electrical characteristic 800 of the active sensor 120 upon introducing the sample effluent 134 containing the anti-infective 1 4 to the active sensor 120. In addition, the analyzer .1 18, the reader 1.14, or a combination thereof can also monitor the electrical characteristic BOO of the control sensor 122 upon introducing the sample effluent 134 without (he anti-infective 104 to the control sensor 122. The analyzer 118, the reader 1 14, or a combination thereof can compare the electrical characteristic 800 of the acti ve sensor 120 with the electrical characteristic 800 of the control sensor 122 to assess the susceptibility of the microorganism 102 to the anti- infeciive 104.

{0063J The electrical characteristic 800 of the sensors i 16 can differ when the solution characteristic 136 of the sample effluents .134 differ as a result of differences in the concentration or the amount of solutes present in the sample effluents .134. For example, the electrical characteristic S00 of the active sensor 120 and the control sensor 122 can differ when the solution, characteristic 136 of the sample effluent 134 introduced to the active sensor 1 20 differ from the solution characteristic 136 of the sample effluent 1.34 introduced to the control sensor 122. As a more specifi example, the electrical characteristic 890 of the active sensor 120 and the control sensor 122 can differ when the solution characteristic 136 of the sample effluents 134 differ in their pH or differ in the concentration of another ion, an organic molecule, or a combination thereof.

|006 | In another embodiment contemplated but not shown in Figure L the analyzer 118, the reader 1 14, or a combination thereof can moni tor the electrical characteristic 800 of one sensor 1 16 upon introducing the sample effluent 134 without the anti-infective 1 to the sensor 1 16. In this embodiment additional nutrient solution 130 comprising the anti- infective 104 can he introduced or exposed to the filter surface 126 comprising the microorganism 1.02 and additional sample effluent 134 resulting from this exposure step can be introduced to the sensor .1 16. The analyzer 118, the reader 1 .14, or a combination thereof can detect any changes in the electrical characteristic 800 of the sensor 1 16 after introducing the additional sample effluent 134 to the sensor ί 16. The analyzer 1 18, the reader J.1.4, or a combination thereof can then assess the susceptibility of the

microorganism .10.2 to the anti-infective 104 usins any detected chan ^g es in the electrical characteristic 800 of the sensor 116,

{O065J In this embodiment, the change in the electrical characteristic 800 of the sensor 11 can indicate a change in the solution characteristic .136 of the sample efflue t 134 introduced to the sensor 116, For example, the change in the solution characteristic 136 of the sample effluent 134 can indicate a change in the concentration of an ion, an organic molecule, or a combination thereof in the sample effluent 134. As a more specific example, the change in the solution characteristic 1 6 of the sample effluent 134 can be a change in the pH of the sample effluent 134. |Θ066| In these and other embodiments, the analyzer 1 18, the reader 1 1 or a

combination thereof can assess the susceptibility of the nucroorgaaisra 102 to the anti- infective 104 ithiri a detection period 138, In one embodiment, the detection period 138 can range from 60 minutes to 240 minutes, in another embodiment _; , the detection period .138 can be less than 60 minutes. In yet another embodiment, the detection period .138 can be greater than 240 minutes.

[0067} The reader 1 1 can produce an output signal 808 (see Figure 8) assessing the susceptibility of the microorganism 102. In one embodiment, the output signal 808 can be an electrical signal. In this embodiment, the output signal 808 can be rendered as a graphic, such as a text string, a number, a symbol, or a combination thereof on a display unit of the reader 114, in another embodiment, the output signal 808 can be an audio signal.

[0068] The analyzer 1 18. the reader 1 14, or a combination thereof can assess the susceptibility of the microorganism 102 to the an ti- infective KM as a binary assessment or a gradated or tiered assessment. In one embodiment, the analyzer 1 1 S, the reader 114, or a combination thereof can assess the susceptibility of the microorganism 102 as either resistant or non-resistant to the anti-infective 104. In this embodiment the system 100 can introduce a set amount of the anti-infective 104 to the nutrient solution 130 and the reader .1 14 or the analyzer 1 18 can assess the susceptibility of the microorganism. 102 as either resistant or .non-resistant based on any detected changes in the electrical characteristic 800 of one sensor 1 16 or any detected differences in the electrical characteristic 800 of the active sensor 120 and the control sensor 122.

f0069| For example, the reader 1 14, the analyzer 118, or a combination thereof can assess the susceptibility of the microorganism 102 as resistant to the anti-infective 104 when the analyzer 1 18 detects a change in the electrical characteristic 800 of the one sensor .1 16 even after anti-infective .104 is introduced to the filter surface 1 6 comprising the microorganism 102. Also, for example, the reader 114, the analyzer 1 .18, or a combination thereof can assess the susceptibility of the microorganism 102 as not resistant to the anti- infective 104 when the analyzer .1 18 fails to detect a change in the electrical characteristic 800 of the one sensor 1 16 when anti-infective 104 is introduced to the filter surface 126 comprising the microorganism .102. Moreover, the reader 1 14, the analyzer 118, or a combination thereof can assess th e susceptibility of the microorganism 102 as not resistant to the anti-infective 104 when the analyzer 1 1 fails to detect a statistically significant change or a change in the electrical characteristic 800 of the one sensor 1 16 exceeding a threshold value. {0070} As another example, the reader 114, (he analyzer 118, or a combination thereof can assess the susceptibility of the microorganism 102 as resistant to the anti-infective 104 when the analyzer 118 or the reader 1 Ϊ4 fails to detect a statistically significant difference between the electrical characteristic 800 of the active sensor 120 and the control sensor .122. More specifically, this statistically significant difference in the electrical characteristic 800 can be a difference exceeding a threshold value. In this example, the system 100 can introduce the sample effluent 134 from the nutrient solution 130 comprising the anti- infective 1 4 to the active sensor 120 and the sample effluent 134 free from an ti- infective 104 to the control sensor 122. In addition, the reader 1 , the analyzer 1 1 S, or a

combination thereof can assess the susceptibility of the microorganism 102 as not resistan t to the anti-infective 104 when the reader 1 .14 or the analyzer 118 detects a statistically significant difference between the electrical characteristic 800 of the active sensor .120 and the control sensor 122 over time,

|0ϋ ^" ? 11 in other embodiments, the reader 1 1 , the analyzer 1 1 S ₄ or a combination thereof can assess the level of susceptibility of the microorganism 102 on gradated, or tiered scale. For example, the reader 1 14 can assess tire susceptibility of the microorganism 1.02 as being resistant, mildly susceptible, or susceptible to the ami -infective 1.04, In these embodiments, anti-tnfccfives 104 of different concentrations can. be introduced to the filter surface 126 comprising the microorganism 102 to assess the level of susceptibility of the microorganism 1 2 to the anti-infective 104,

0072| As a more specific example, when only one sensor ί 16 is used to assess the level of susceptibility of the microorganism 102, the system .100 can introduce larger amounts of the and -infective 104 to the filter surface 126 over time and monitor the effects of the additional anti-infective 104 on the electrical characteristic 800 of the sensor 1 16 over sn.eh a time period. As another example, when multiple active sensors 120 are disposed on the substrate 1 12, the system .100 can introduce differing amounts of the anti- infective 1 4 to different active sensors 120 simultaneously or over time and the reader 1. ] 4, the analyzer 1 .1 , or a combination thereof can compare the electrical characteristic 800 of the various active sensors 120 with the control sensor 122 to assess the level of susceptibility of the microorganism .102 to the anti-infective 104.

fO073J While three categories of susceptibility are discussed in the section above, it should be understood by one of ordinary skill in the art that four or greater categories of susceptibility can be used to assess the level of susceptibility of the microorganism .1 2 to the anti-infective 104. {0074} Figure 2 illustrates another embodiment of the system 100 for detecting or assessing the susceptibilit of a microorganism 102 to an anti-infective 104. The sy stem 100 can comprise the fluid delivery device 1 6, the substrate 12 comprising substrate wells 200, and the reader 1 14, The substrate 1 .12 can have one or more sensors 1 .16 disposed on a substrate surface 202. The system 100 can also include the analyzer 118. In the embodiment shown in Figure 2, the analyzer 1 18 can be disposed on the substrate surface 202. In other embodiments, the analyzer 1 18 can be a standalone unit or device coupled to the substrate 1 12.

{0075} The sensors 1 16 can include one or more active sensors 120, one or more control sensors 122, or a combination thereof disposed on the substrate surface 202. As illustrated hi the embodiment shown in Figure 2, the active sensors 120 and control sensors 122 can be disposed on one side of the substrate 112. hi other embodiments not shown in Figure 2, the active sensors 120 and the control sensors 122 can be disposed on different sides of the substrate 112 or on different substrates. For example, Figure 2 shows the substrate 1 .12 having three sensors 1 16; however, it is contemplated that the substrate 1 12 can comprise any number of sensors 1 16. In one embodiment, at least one of the sensors 116 can be ISFET.

{0076} The substrate weils 200 can include a sample well 204, one or more active wells 206, one or more control weils 208, or a combination thereof. The sample well 204, the one or more active weils 206, the one or more control weiis 208, or a combination thereof can be fluidiy coupled to or be in fluid communication with one another through substrate channels 210. The substrate channels 210 can include tubes, capillaries, microti uidic channels, indentations, or holes disposed on or inside the substrate 1 12.

{0077} The substrate wells 200 including the sample well 204, the acti ve well 206, the control wells 208, or a combination thereof can be divots, indentations, or openings on the surface of the substrate 1 1 2. In another embodiment, the substrate wells 200 can be enclosed spaces within the substrate 1 12. In other embodiments, the substrate wells 200 can be receptacles or cartridges coupled to the substrate 112. The substrate wells 200 can also be f!nidly coitpied to or be in fluid communication with the sensors 1 16 through the substrate channels 210,

{0078} As illustrated in Figure 2, the fluid delivery device 106 can deliver or inject the fluid sample 124 comprising the microorganism 1 2 into the sample well 204 in step 2A. in an alternative embodiment not shown in Figure 2, the fluid sample 124 can be pre- filtered in a step before step 2A. This pre-fi tering step can involve filtering the fluid sample 124 using the filter 1 10, a mierofiuidic filter, or a combination thereof to filter out other larger cellular components including blood cells or epithelial ceils from the .fluid sample 124.

|¾079] The same fluid delivers' device 106 or another fluid delivery device 106 can also be used to deliver or inject the nutrient solution 130 to the sample well 204 in step 2B. The fluid delivery device 106 can continuously or periodical iy introduce or expose tbe substrate surface 202 of the sample well 204 with the nutrient solution 130. in one embodiment, the nutrient solution 1 0 can be composed of a buffer containing bacto- tryptone, yeast extract, sodium chloride and any combinations thereof, in another embodiment the nittrtent solittton can include a growth inducer. The growth inducer can be selected from the group consisting of a carbon-based inducer, a nitrogen-based inducer, a mineral, a trace element, a biological growth factor, or any combination thereof. For example, the growth inducer can include but is not limited to glucose, ammonia,

magnesium, or a combination thereof. For example, the nutrient solution 130 can be O.lx Luria Broth supplemented with 1.00 mM glucose.

{0080} The flow of the iiut.rie.ot solution 130 can carry or deliver the microorganism 1.02 in the sample well 204 to the aeti ve well 206, the control well 208, or a combination thereof. For example, the sample well 204, the active well 206, the control well 208, or a combination thereof can be shaped as a hemisphere having a rounded bottom, a cuboid having a flat or planar bottom, a cone, a frastoeonieal, a hype.rbolo.kl or a combination thereof. The entire substrate .1 12 can be heated to a temperature between 30 "C to 40 "C when the microorganism 102 is in the active well 206, the control, well 208, or a combination thereof and allowed to incubate for the incubation period 132. The substrate 1 12 can be allowed to incubate in order to promote the proliferation, metabolism, or growth of the microorganism 102 in the active wells 206, the control wells 208, or a combination, thereof.

[0081] The substrate wells 200, including the sample well 204, the active well 206, the control well 208, or a combination thereof, can be covered by a well coating 212. The well coating 212 can. cover or coat the bottom or sides of the wells. The well coating 212 can include an anti-buffer coating such as an acidic coating or a basic coating.

(0082} The well, coating 212 can also be a trapping coating configured to trap the microorganism 102 in the active wells 206, the control, wells 208, or a combination thereof For example, the well coating 212 can be an extracellular matrix comprising proteins such as .fibronectio, collagen, laminin, osteopontin, poiy-D-lysine, or a combination thereof The well coating 212 can also be a charged coating such as an amine surface, a carboxyl surface, a charged peptide surface, or a combination thereof The well coating 212 can also be an oxygen or nitrogen containing surface. The well coating 212 can also be a polyurethane surface.

[0083] The active we!ls 206, the control wells 208, or a combination thereof can have a physical barrier 214. The physical barrier 214 can be a physical feature or design of the well for trapping or isolating the microorganism .102 in the active well 206, the control well 208, or a combination thereof. For example, the physical barrier 214 can be an overhang or li p protruding from a downstream section of the active well 206, the control well 208, or a combination thereof. As another example, the physical barrier 214 can be a sloping surface of the active well 206, the control well 208, or a combination thereof. In another embodiment contemplated but not shown in Figure 2, the physical barrier 214 can be the filter 1 10 disposed at an opening of the active well 206, the control well 208, or a

combination thereof downstream from the sample well 204.

|0084| Although the example embodiment in Figure 2 shows the physical barrier 214 as a feature of the substrate wells 200, the phy sical barrier 214 can also be a feature of the substrate channels 210, For example, the substrate channels 21 can be microti uidic channels, which, narrow to a width, or diameter which, prevent the microorganism 1 2 from proceeding down the substrate channels 21 toward the sensors 116. in this example embodiment, die substrate 112 can act as a microftiridk chip or lab-on-chip (LOG).

{ ^' (KtSS ^' j The well coating 212 ₇ the physical barrier 214. or a combination thereof can be included as part of the system .1 0 to prevent, or stop the microorganism 1 2 from

contacting or reaching the sensors 11 . in another embodiment contemplated but not shows in Figure 2, an electrical or magnetic component can he used to trap or isolate the microorganism 102 in the active well 206, the control well 208, or a combination thereof.

[0086] The nutrient solution 130 delivered in step 2B or additional nutrient solution 130 can be continuously or periodically delivered or injected into the sample well 204, the acti ve well 206, the control well 208, or a combination thereof until the microorganism 102 is carried or delivered into one or more active wells 206, control wells 208, or a

combination thereof The active wells 206, the control wells 208, or a combination thereof caft comprise one or more openings, physical features, geometries, or device features which, allow fluid or supernatant in. the active wells 206, the control wells 208, or a combination thereof to evacuate or exit the wells into one or more substrate channels 21.0. The fluid or supernatant separated from the microorganism 102 in the active wells , the control wells 208, or a combination thereof cat) be referred to as the sample effluent 134.

jO087{ As illustrated in the example embodiment, shown in. Figure 2, the sample effluent 134 cart be introduced,, carried, or delivered to one or more of the sensors 1 .16 disposed ort the substrate 1 12. The sample effluent 134 cart comprise a solution characteristic 136. The solution characteristic 136 can include an amount or concentration of ions, organic molecules such, as amino acids, minerals, or other inorganic compounds in the sample effluent 134.

{0088} The solution characteristic 136 can vary as a result of ions, organic molecules, or minerals produced by or attributed to the microorganism 102 in the active wells 206, the control wells 208, or a combination thereof. The solution characteristic 136 can be a direct or indirect byprod uct of a cellular activity undertaken by the microorganism 102 such as cell metabolism or cell growth. The sample effluent 134 can comprise ΉΓ, ATP, COj, lactic acid, carbonic acid, N<¾\ or a combination thereof.

{0089| The substrate channels 120 can deliver or introduce sample effluent 1 4 from one or more active wells 206 to one or more active sensors 120. In addition, separate substrate channels 120 can deliver or introduce sample effluent 134 from one or more control wells 208 to one or more control sensors i 22.

[00901 After or prior to incubating the substrate 11 , the same fluid deli very device 106 or another fluid delivery device 106 can be used to introduce an anti-infective 104 to the active wells 206 in a step 2C. In the example embodiment shown in. Figure 2, the anti- infective 104 can b mixed with additional nutrient, solution 130 and the active wells 206 comprising the microorganism .1 2 can be exposed to additional nutrient solution 130 comprising the anti-infective 104. In other embodiments, the anii -infective 104 can be introduced to the active wells 206 separate from the nutrient solution 130.

{60911 to the example embodiment shown in Figure 2, nutrient solution 130 containing the anti-infective 104 can be delivered or introduced to the active well 206 comprising the microorganism 102 while nutrient solution 130 lacking the anti-infective 104 can be delivered or introduced to the control well 208 also comprising the microorganism 102, In these embodiments, the sample effluent 134 flowing from the active well 206 can be introduced to the active sensor 120 and the sample effluent 134 flowing from the control well 208 can be introduced to the control sensor 122.

{00921 to an alternative embodiment contemplated but not. shown in Figure 2, one active welt 206 can initially be exposed to nutrient solution 130 lacking in anti-infective 104 and the sample effluent 134 flowing from the active well 206 can be introduced to a sensor 11 (>. In this embodiramt, the same active well 206 ca» be exposed at a later time with nutrient solution 130 comprising the anti-infective 1 4. By doing so, the sample effluent 134 from this second exposure step can he introduced to die same sensor 1 1 as the sensor 116 used to measure the noii-anti-infecdve sample effiuent 134.

{0093 J While Figure illustrates two of the three sensors 1 16 on the substrate 11 being used to analyze sampie effluent 134 from the fluid sample 124, it is contemplated that the substrate 112 can accommodate any number of sensors 1 1 (> for receiving the sample effluent 134. For example, the substrate 112 can be a support or housing for a high throughput assay plate such as a 96-well plate, a 192-weli plate, or a 384-weli plate. In this example, each of the well plates can be in fluid communication with at least one sensor 1 16.

f00 4J The reader 1 14, the analyzer 1 18, or a combination thereof can be configured to monitor the eiectricai characteristic S00 of the sensors 116 upon introducing the sample effluent 134 to the sensors 1 16. For example, the reader 1 1 can monitor the electrical characteristic 800 of the sensors 1 1 by receiving one or more signals from the analyzer 118 disposed on the substrate 112.

{00 5J In the example embodiment shown in Figure 2, the analyzer 11 , the reader 114, or a combination thereof can monitor the electrical characteristic BOO of the sensors 116, such as the active sensor 120 and the control sensor 122 in step 2D, The analyzer 1 18, the reader 114, or a combination thereof can. monitor the electrical characteristic 800 of the active sensor 120 upon introducing the sampie effiuent 134 from the active well 206 to the active sensor 120. hi addition,, the analyzer .1 18, the reader 114, or a combination thereof can also monitor the electrical characteristic 800 of the control sensor 122 upon introducing the sampie effluent 134 from the control well 208 to the control sensor .1 22. The analyzer .1 18, the reader 114, or a combination thereof can compare the eiectricai characteristic 800 of the active sensor 120 with t he electrical characteristic 800 of the control sensor 122 to assess the susceptibility of the microorganism .102 to the anti-infective .1 4.

fOO j The electrical characteristic 800 of the sensors 11 can differ when the solution characteristic 136 of the sample effluents .134 differ as a result of differences in the concentration or the amount of solutes present, in the sample effluents 134. For example, the electrical characteristic 800 of the active sensor 120 and the control sensor 122 can differ when the solution characteristic 136 of the sample effluent 134 introduced to the active sensor 120 differ from the solution characteristic 136 of the sample effluent 134 introduced to die control sensor 122.

{O097J in another embodiment contemplated but not shown in Figure 2, the analyzer 1 18, the reader 114, or a combination thereof can monitor the electrical characteristic 800 of one sensor 1 16 upon introducing the sample effluent 134 without the anti-infective 104 to the sensor 1 16, in this embodiment, additional nutrient solution 130 comprising the anti- infective 104 can be delivered or exposed to the same sensor 116 and additional sample effluent 134 resulting from this exposure step can be introduced to the sensor 1 16. The analyzer 1 18, the reader 1 14, or a combination thereof can detect any changes in the electrical characteristic 800 of the sensor 1 16 after introducing the additional sample effluent 134 to the sensor 116. The analyzer 1 .18, the reader 114, or a combination thereof can then assess the susceptibility of the microorganism 102 to the anti-infective 104 using any detected c hanges in the electrical characteristic 800 of the sensor 1 16,

£0098] in this embodiment, the change in the electrical characteristic 800 of the sensor 1 1 can indicate a change in the solution characteristic 136 of the sample effluent 1 4 introduced to the sensor 116. For example, the change i the solution characteristic 136 of the sample effluent 134 can indicate a change in the concentration of an ion, an organic molecule, or a combination thereof in the sample effluent 134. As a more specific example, the change in the solution characteristic 136 of the sample effluent 134 can be a change in the pH of the sample effluent 134.

{0099J In these and other embodiments, the analyzer 1 18, the reader 1 14, or a combination thereof can assess the susceptibility of the microorganism 102 to the anti- infective 104 within the detection period 138.

{0100} The reader 1 14 can also produce the output si nal 808 assessing the susceptibility of the microorganism 102. The analyzer 1 I S, the reader 114, or a combination thereof can assess the susceptibility of the microorganism 102 to the anti- infective 104 as the binary assessment or die gradated or tiered assessment.

[01011 For example, the reader .1 14, the analyzer 118, or a combination thereof can assess the susceptibility of the microorganism 102 as resistant to the anti-infective 104 when the analyzer 118 detects a change in the electrical characteristic 800 of the active sensor 120 even after anti-infective 1 4 is introduced to the active well 206 fluidiy coupled to the active sensor 120. Also, for example, the reader 1 14, the analyzer 118, or a combination, thereof can assess the suscepti bility of the microorganism 102 as not resistant to the anti-infective 1 4 when the analyzer 1 18 fails to detect a change in the electrical characteristic 800 of the active sensor 120 when anti-infective 104 is introduced to the active well 206 fluidly coupled to the active sensor 120. Moreover, the reader 1 14, the analyzer ί 18, or a combination thereof can assess the susceptibil it of the microorganism .1 2 as not resistant to the anti-infective 104 when the analyzer 118 fails to detect a statistically significant change or a change in the electrical characteristic 800 of the active sensor 120 exceeding a threshold value.

£01021 As another example, the reader 1 1 , the analyzer ί 18, or a combination thereof cart assess the susceptibility of the microorganism 102 as resistant to the an i -infective 10 when the analyzer 118 or the reader 1 14 fails to detect a statistically significant difference between the electrical characteristic 800 of the active sensor 120 and the control sensor .122. More specifically, a statistically significant difiere.nce in the electrical characteristic 800 can be a difference exceeding a threshold value, in this example, the system .100 can introduce the sample effluent 134 from the active well 206 to the active sensor 120 and the sample effluent 134 from the control well 208 to the control sensor 122. in addition, the reader 1 .14, the analyzer 118, or a combination thereof can assess the susceptibility of the microorganism 102 as not resistant to the anti- i fecti ve 104 when the reader 1 1 or the analyzer 1 18 detects a statistically significant difference between the electrical characteristic 800 of the acti ve senso 120 and the control sensor 122.

[01031 In other embodiments, the reader 1 14, the analyzer 11 , or a combination thereof can assess the level of susceptibi lity of the microorganism 102 on a gradated or tiered scale. For example, the reader 1 14, the analyzer 118, or a combination, thereof can. assess the susceptibility of the microorganism 102 as being resistant, mildly susceptible, or susceptible to the anti-infective 104. in these embodiments, am; -infectives 104 of different concentrations can be introduced to different active wells 206 comprising the

microorganism 102 to assess the level of susceptibility of the microorganism 102 to the anti-infective 104.

[01041 As an example, when only one sensor 1 16 is used to assess the level of susceptibility of the microorganism .102, the system 1 0 can introduce larger amounts of the art ti -infective 104 to the active well 206 over time and monitor the effects of the additional anti-infective 104 on the electrical characteristic 800 of the active sensor 120 fluidly coupled to the active well 206 over such a time period. As another example, when multiple active sensors 120 are disposed on the substrate 1 12, the system 100 can introduce differing amounts of the anti-infective 104 to different active wells 206 and the reader 1 .14, the analyzer 1 18, or a combination thereof can compare the electrical characteristic 800 of the various active sensors 120 with one or more control sensors 122 to assess the level of susceptibility of the tmcroorganism 102 to the anti-infective 104.

j6105{ Figure 3 illustrates another embodiment of the system 100 for detecting or assessing the susceptibility of a microorganism 102 to an and -infective 104. The system 1 0 can comprise the fluid delivers' device 106, ihe filter housing 108 containing the filter 1 1 , and a sensor device 300, in one embodiment, the sensor device 3(H ⁾ can be a handheld ISFET meter or probe.

|0i.06| As illustrated in Figure 3, the fluid delivery device 106 can deliver or inject the fluid sample 124 comprising the microorganism 102 into the filter housing 108 in step 3 . In the example embodiment shown in Figure 3, the fluid delivery device 106 can be a syringe. In oilier embodiments not shown in Figure 3, the fluid delivery device 106 can be an injection cartridge, a microfloidic device, a pipette, a reaction tube, a capillary, a test tube, a combination thereof, or a portion therein.

|01 7[ The filter housing 108 can he a container or vessel configured to secure or enclose the filter .1 1 . For example, the filter housing 108 can be a housing of a syringe filter. The filter ! 10 can be a mesh or matrix for isolating or separating the microorganism 102 or other molecules or cells from the supernatant of the fluid sample 124.

|O!08| The filter 110 can comprise a filter surface 126. The filter surface 126 can be the portion of the filter 110 used to isolate or trap the microorganism 102, The filter surface 126 can include an external surface, an internal surface extending into the filter 110, or a combination thereof. Although not shown in Figure 3, the filter housin 108 can have at least one opening 128 to allow fluid or supernatant from the fluid sample .124 to e vacuate the filter housing .1 8. For example, step 3A can include the additional step of discarding the fluid or supernatant from the fluid sample 124 through the opening 128 after isolating the microorganism 1 2 on the filter surface 126.

[0109] In an alternative embodiment not shown in Figure 3. the fluid sample 124 can be pre-filtered in a step before step 3A, This pre-filtering step can involve filtering the fluid sample .124 using another instance of die filter 1 10, a microfluidic filter, or combination thereof to filter out other larger cellular components including blood ceils or epithelial, cells from the fluid sample 124 when the fluid sample 124 is composed of a bodily fluid or sample.

|6110| The same fluid delivery device 1 6 or another fluid del iver device 106 can also be used to deliver or inject a nutrient solution 130 to the filter housing 108 in step 3.B. The fluid delivery device 1 6 can continuously or periodically introduce or expose the nutrient solution 130 to ihe filter surface 126 containing the microorganism 102. In one embodiment, the nutrient solution 130 can be composed of the growth inducer, Litria Broth, aCL and the buffer.

|¾J 11] The filter housing 108 comprising the nutrient solution i 30, the filter, and the microorganism 1 2 can be heated to a temperature of around 37 ^{' '} C and allowed to incubate for an incubation period 132 in a step 3C. The incubation period 132 can range from 15 minutes to one hour, in other embodiments, the incubation period 132 can be less than 15 minutes. The incubation period 132 can be adjusted based on the type of microorganism 102.

|01 !2J The incubation period J 32 can also be adjusted based on the amount of the microorganism 102 present in the fluid sample .124. For example, the incubation period 132 can be increased when the amount of the microorganism: 102 is below a threshold amount. The filter } !O can be allowed to incubate with the nutrient solution 1 0 in order to promote the metabolism of the microorganism 102 on the filter i 10, Furthermore, by monitoring the rate at which metabolites are produced using the sensor herein described, it is possible to identify the microorganism, as different microorganisms have characteristic rates of multiplication and metabolism. There is an additional feature hereby disclosed, namely providing different nutrients to the microorganisms over time while monitoring the rate of production of various metabolites using the sensor herein described in order to further identify the microorganism,

[till 3 j After incubating the filter housing i OS, the filter 1 i 0 comprising the microorganism 102 can be separated from a solution representing the leftover nutrient solution 130 in the filter housing 108, This solution can be referred to as the sample effluent 134, The sensor device 300 can then be introduced or inserted in to the sample effluent 134 in. step 3D to determine the solution characteristic 136 of the sample effluent 134. In another embodiment contemplated but not shown in Figure 3. the sample effluent 134 can be evacuated or removed from the filter housing J OB through an opening in the filter housing 108 into another container or vessel. The sensor device 300 can then be used to determine the solution charactensiic 136 of the sample effluent 134 in this other container or vessel.

|©114J The solution characteristic 136 can refer to one or more attributes of the solution making up the sample effluent 134. For example, the solution characteristic 136 can include a concentration of a solute or an absolute number of solute molecules in solution. The solution characteristic 136 can include an amount or concentration of ions. organic molecules such as amino acids, minerals, or other inorganic compounds in the sample et!Iuent 134.

(6115J The solution characteristic 136 can vary as a result of ions, organic molecules, or minerals produced by or attributed to the microorganism .1 2 on the filter .1 1 . The solution characteristic 136 can be a direct or indirect byproduct of a cellular activity undertaken by the microorganism 102 such as cell metabolism or cell growth. In one embodiment, the sample effluent 134 c n comprise hydrogen ions (if ) as a byproduct of bacterial cell metabolism or growth. In other embodiments, the sample effluent 134 can comprise adenosine triphosphate (ATP), carton dioxide (CO?.), iactic acid, carbonic acid, nitrates (NCV), a combination thereof, or any other metabolic byproduct produced by or attributed to the microorganism 102.

|¾I 16] After step 3C, die filter 1 10 comprising the microorganism 1 2 can be removed from the filter housing 108 containing the sample effluent 134 and placed into a new -filter housing 108. The same fluid delivery device 106 or another fluid delivery device 1 6 caa then be used to introduce an anti-infective 1 4 to the new filter housing 108 containing the filter 11 in a step 3E. In an alternative embodiment step 3E can involve using the same fluid delivery device 106 or another fluid delivery device 106 to introduce an anti-infective .10 to the filter bousing 108 from step 3C after the sample effluent 134 has been evacuated or removed from the opening of the filter housing 108,

In the example embodiment shown in Figure 3, the an ti -infective 104 can be mixed with additional nutrient solution 1 30 and the filter ί 10 comprising the

microorganism 102 can be exposed to additional nutrient solution 130. In other embodiments, the anti-infective 104 can be introduced to the filter 110 separate from the nutrient solution 130,

fill I8{ After introducing the anti-infective 104 to the filter housing 108, the filter housing 108 comprising the nutrient solution 130, the filter 110, the anti-infective 104, and the microorganism 1 2 can he heated to a temperature of around 37 °C and allowed to incubate for an incubation period 132 in a step 3F.

|01.J9j After incubating the filter housing 108, the filter 1 .1 comprising the microorganism 102 can be separated from the sample effluent 134. A sensor device 300 can then be introduced or inserted into the sample effluent 134 in step 3G to determine the solution characteristic 136 of the sample effluent 134. In another embodiment contemplated but not shown in Figure 3, the sample effluent 134 can be evacuated or removed f om the filter housing 108 through an opening in the filter housing 108 into another container or vessel The sensor device 300 can then, be used to determine the sol ution characteristic 136 of the sample effluent 134 in this other container or vessel jO120{ The reader i 14 can then be used to compare the solution characteristic 136 of the sample effluent 134 from step 3d with the solution characteristic 136 of the sample effluent 134 from step 3D to assess the susceptibility of the microorganism 1 2 to the anti- infective 104 in step 3H, For example, the reader 1 14 can be used to compare the two solution characteristics 136 over time. The solution characteristic 136 from step 3D and step 3G can differ as a result of differences in the concentration or the amount of solutes present in the sample effluents 134. For example, the solution characteristic .136 can differ in their pH or differ in the concentration of another ion, an. organic molecule, or a combination thereof.

[0121] The reader 114 can assess the susceptibility of the microorganism 102 to the anti-infective 1 4 within a detection period 138. in one embodiment, the detection period 138 can range from 60 minutes to 240 minutes. In another embodiment, the detection period 138 can be less than.60 minutes, in yet another embodiment, the detection period 138 can be greater than 240 minutes.

{0.122} The reader 114 can produce an output signal 80S assessing the susceptibilit of the microorganism 102. In one embodiment, the output signal 808 can. be an electrical signal. In this embodiment, the output signal 808 can be rendered as a graphic, such as a text string, a number, a symbol, or a combination thereof on a display unit of the reader 1 ] 4. In. another embodiment, the output signal 80 can be an audio signal

{0123} The reader 1 14 can assess the susceptibility of the microorganism .102 to the anti-infective 104 as a binary assessment or a gradated or tiered assessment. In one embodiment, the reader 1 14 can assess the susceptibility of the microorganism 102 as either resistant or non-resistant to the anti-infective 104, In this embodiment, the reader 114 can assess the susceptibility of the microorganism: 102 as either resistant or non-resistant based on any detected differences in the solution characteristic 136,

|ul24| For example, the reader 1 14 can assess the susceptibility of the microorganism 102 as resistant to the anti-infective 104 when the reader 1 14 .fails to detect a statistically significant difference between the solution characteristic 136 from: step 3D and the solution characteristic 136 from step 3G over time. A statistically significant difference can refer to a difference exceeding a threshold value. Also, the reader 1 14 can. assess the susceptibility of the microorganism 102 as sensitive to the anti-infective 104 when the reader 1.14 detects a statistically significant difference between the solution characteristic 136 from step 3D and the solution characteristic 136 from step 3G over time.

j0l25{ In other embodiments, the reader 1 14 can assess the level of susceptibility of the microorganism 102 on a gradated or tiered scale. For example, the reader 1 14 can assess the susceptibility of the microorganism 102 as being resistant, mildly susceptible, or susceptible to the anti-infective 104. in these embodiments, anti-infeerives 104 of different concentrations can be introduced to the filter housing 108 in step 3E to assess the level of susceptibility of the microorganism .102 to the anti-infective 104. The reader 1 14 can compare the solution characteristic 136 of the various sample effluents 134 over time to assess the level of susceptibility of the microorganism 1 2 to the anti-infective 104,

[0126] Figure 4A illustrates a side view of an embodiment of the substrate 112 having the active sensor 120 disposed on the substrate 1 1 2 and an external reference electrode 400 extending into a measured liquid 402 in contact with the active sensor 120. As depicted in Figure 4A, the substrate 1 12 can be comprised of a substrate carrier layer 404 and a base dielectric layer 406. The substrate 1 12 can be a polymer layer, a metal layer, a metalloid layer, a ceramic layer, an organic semiconductor, an organic conductor such as those deri ved from polyacetylene, polyaniline, Quinacridone, or a combination thereof. For example, the substrate 1 12 can be composed of silicon or an oxide of silicon which allows a voltage to be applied through the substrate 112 to the sensor channel 10,

j¾12?| The base dielectric layer 406 can be coupled or can be disposed on the substrate carrier layer 404 to electrically insulate or isolate each of the sensors 1 16 from one another. In one embodiment, the base dielectric layer 406 can be composed of an oxide material, hi other embodiments, the base dielectric lay er 406 can be composed of an other material capable of providing insulation.

j0128| in one or more embodiments, the sensors 1 16 of the system 100, including the active sensor 1 20. the control sensor 122, or a combination thereof can be fabricated usins a complementary metal oxide semiconductor (CMOS) process. For example, the active sensor 120, the control sensor .122, or a combination thereof can be integrated CMOS

ISFET sensors fabricated from p-type and n-type metal oxide semiconductor field-effect transistors (MOSFETs). n another embodiment, the sensors 116 can be organic field-effect transistors (OFETs),

fO!2*>J As depteted in Figure 4 A, the active sensor 120 can comprise sensor contacts 408, a sensor channel 41.0 in between the sensor contacts 408, a gate dielectric layer 412 coupled to or on top of the sensor channel 41 , and an encapsulating layer 414 partiall covering the gate dielectric layer 41 of the active sensor 120. The sensor contacts 408 can include a source contact and a drain contact. For example, the sensor contacts 408 can be composed of highly doped p-type material. The sensor channel 410 can act as a bridge between the two sensor contacts 408 and can be composed of an electrically conductive material or coating that allows for electrical communication between the sensor contacts 408.

[01301 The gate dielectric layer 412 can be coupled to or disposed on top of the sensor channel 410. in certain embodiments, the gate dielectric layer 412 can be a high-k dielectric layer or a material layer having a high dielectric constant (k). For example, the gate dielectric layer 412 can comprise aluminum oxide, hafnium oxide, titanium oxide, zirconium oxide, yttrium oxide, tantalum oxide, hafnium silicate, zirconium silicate, silicon nitride, aluminum nitride, hafnium nitride, zirconium nitride, or a combination thereof. As a more specific example, the gate dielectric layer 412 can comprise aluminum dioxide, hafnium dioxide, zirconium dioxide, or a combination thereof. In other embodiments, the gate dielectric layer 412 can comprise a silicon dioxide layer.

{0.131} Any of the sensors 1 16, including the active sensor 120 and the control sensor 122, can be partially covered by the encapsulating layer 414. The encapsulating layer 414 can be composed of any inert or non-conductive material for protecting the sensor 1 16 froni being exposed to solutes or contaminants in the measured liquid 402 that would damage or degrade the sensor 1 16.

|(il32j As depicted in Figure 4.4, the system 100 can also comprise an external reference electrode 400 in liquid communication with the measured liquid 402 and the sensor 116 itself. The measured liquid 402 can refer to any of the sample effluent 134. the nutrient solution 130, the fluid sample 124, a portion therein, or a combination thereof. The fluid sample 124 cao. be introduced to the sensors 1 16 from the filter housing 108, the substrate wells 200, or any other fluid deli ery device 106. The fluid sample .124 can cover the active sensor 1.20, the control sensor 122, or a combination thereof when, introduced to the sensors 1 16. in other embodiments, the fluid sample .124 can partially cover or be in liquid communication with the active sensor 120, the control sensor .122, or a combination thereof when introduced to the sensors 11 .

(0133} The external reference electrode 400 can apply a potential such, as a .liquid gate potential, to the measured liquid 402. in one embodiment, the external, reference electrode 400 can be a standalone probe or electrode. In other embodiments, the external reference electrode 400 can be coupled to the reader 1 14, the analyzer 1 18, or a combination thereof. The external reference electrode 400 can. have a stable and well-known internal voltage arid caa act as a differential noise filter for removing electrical noise from measurements taken by the sensors ί 1.6.

[0134] In one embodiment, the external reference electrode 400 can be a silver/silver chloride (Ag/AgO) electrode. n other embodiments, the external reference electrode 400 can be a saturated calomel reference electrode (SCE) or a copper-copper (11) sulfate electrode (CSE).

{0135| The system 100 can use the external reference electrode 400 to determine or record a relati ve change in the electrical characteristic $00 of the active sensor 120 rather than having to ascertain an absolute change. The system 100 can also use the external reference electrode 400 to determine or record a relative difference between the electrical characteristic 800 of the active sensor 120 and the control sensor 122.

|¾ ^' !36J A back-gate voltage Vbg can be applied via the silicon substrate. The electrical characterization of iSFETs cart be performed by applying a source-drain voltage Vscl to measure the source-drain current Isd. In another embodiment, a liquid gate voltage can be applied to a solution via a reference electrode. The electrical characterization of ISFETs can be performed applying a source-drain voltage Vsd to measure the source-drain current. Isd. in another embodiment, a dual-gate approach can be used by applying gate voltages simultaneously to the back gate and to the liquid gate. This allows an operator to tune the device to different working positions, optimizing the sensitivity. The back-gate voltage Vbg is applied to the Si substrate, while the liquid gate voltage Via is applied via a reference electrode. At the same time, the liquid potential VI can be measured by the reference electrode. When the ion concentration in the solution is changing, the ISFET responds with a change in the electrical characteristic. For example, in case of proton (H ) changes, the protons interact with the ox ide surface of the ISFET, This is the expected dependence for an oxide surface exposing hydroxl (-OH) groups to the liquid. The change in surface charge density caused by a pH change is described by the site-binding model, which takes into account that -OH groups can be protonated or deprotonated. This model predicts an approximate linear relation between the surface charge density and the proton concentration. Since the surface charge acts as an additional gate, the ISFET is responding to the additional gate effect,

|0137J Figure 4B illustrates a side view of another embodiment of the substrate 1 12 having the active sensor 120 and an. on-chip reference electrode 416 disposed on the substrate 11.2. The on-chip reference electrode 416 can serve the same purpose as the external reference electrode 400 except fabricated as a chip or sensor on the substrate 112. The on-chip reference electrode 416 cart be located adjacent to or near the active sensor 120, The on-chip reference electrode 416 can be coupled to the base dielectric layer 406. The on-chip reference electrode 4 J 6 can also be partially covered by the encapsulating layer 414. The on-chip reference electrode 416 can apply a liquid gate voltage (Vto) to the measured liquid 402.

£01381 The on-chip reference electrode 16, the external reference electrode 400„ or a combination thereof can be comprised of a metal,, a semiconductor material, or a combination thereof In one embodiment, the control sensor 122 can act as the on-chip reference electrode 416. The metal of the on-chip reference electrode 416 can be covered by an oxide layer, a siiane layer, or a combination thereof. Since metals or other materials used to fabricate such reference electrodes can often have an inhibitory or harmful effect on the microorganisms 1 2 under investigation, one advantage of the methods and systems 100 disclosed herein is the separation of the microorganism 1 2 from the components of the system 100 in. physical or fluid contact with these reference electrodes.

|0I35>| For example, the external reference electrode 400 can be an Ag/AgCl reference electrode, in this example, silver ions or a silver surface making up the external reference electrode 400 can act as an anti-infective agent when placed into contact with certain types of bacteria or iisngi. By separating the sample effluent 134 from the bacteria, or fungi representing the microorganism 102, the system 100 can prevent .false positi ve or .false negative results stemming from the antibacterial effects of the reference electrode on the microorganism 102 under investigation. For example, the filter 1 10 or the substrate wells 200 can trap or isolate the microorganism 102 but permit the nutrient solution 130 or the sample effluent 134 to reach the sensors 1 16 and the reference electrode.

|0140| The on-chip reference electrode 416 can he a transistor with very similar electrical properties as compared to the sensor 1 16 but with a passivated surface, the so- called reference FET (RFBT). The RFET can be an ISFET with a pB-passivating membrane, ion-blocking layers of photoresist material, or other polymers. The on-chip reference eiecirode 416 can comprise one or more pH-insensttive layers covering an ISFET. Such pli-insensitive layers can include siianes, self-assembled mono layers (SAMs), buffered hydrogcls, PVC, parylene, poly ACE, or any other chemically inert material. Also a metal, such as Ag or Ft, can be used as a quasi-reference electrode evaporated on the substrate carrier. In another embodiment, the on-chip reference electrode 416 can be a metal combined with a metal salt such as an Ag/AgCl reference eiecirode. |01411 Figure 5A illustrates a side view of yet another embodiment of the substrate 1 12 having the acti ve sensor 120 and a control sensor 122 disposed on the substrate 112 and the external reference electrode 400 extending into the measured liquid 402 in contact with the active sensor 120 and the control sensor 122. Similar to die active sensor .120, die control sensor .122 can comprise a pair of sensor contacts 408, a sensor channel 410 in between the sensor contacts 408, a gate dielectric layer 412 coupled to or on top of the sensor channel 10, and an encapsulating layer 414 partially covering the gate dielectric layer .12 of the control sensor 1 22.

{0142} The sensor contacts 408 can include a source contact and a drain contact. The sensor channel 410 can act as a bridge between the two sensor contacts 408 and can be composed of any electrically conductive material or coating that allows for electrical communication between the sensor contacts 408.

{0143 J The gate dielectric layer 412 can be coupled to or disposed on top of the sensor channel 410, in certain embodiments, the gate dielectric layer 412 can be a higfa-k dielectric layer or a material layer having a high dielectric constant. For example, the gate dielectric layer 412 of the control sensor 122 ca comprise aluminum oxide, hafnium oxide, titanium oxide, zirconium oxide, yttrium oxide, tantalum oxide, hafnium silicate, zirconium silicate, or a combination thereof. As a more specific example, the gate dielectric layer 412 can comprise aluminum dioxide, hafnium dioxide, zirconium dioxide, or a combination thereof, in other embodiments, the gate dielectric layer 412 can comprise a silicon, dioxide Saver.

{01.44} The encapsulating layer 414 can be composed of any inert o non-conducti ve material tor protecting the control sensor 122 from being exposed to solutes or contaminants in the measured liquid 402 that would damage or degrade the control sensor ] "??

[0145] In the example embodiment shown in Figure 5A, the control sensor 122 can. comprise a passivation layer 500 coupled to or disposed on the gate dielectric layer 412. The passivation layer 500 can be composed of a polymer layer, a metallic layer, a self- assembled monolayer (SAM), or a combination thereof. The passivation layer 500 can be used to prevent binding of ions or molecules to the surface of the control sensor 1 22. In other embodiments, the control sensor 122 can. be without the passivation layer 500 and the makeup of the control sensor 122 can be iden tical to the acti ve sensor 120. For example, the passivation layer 500 can be a pil-passivating membrane, an ion-blocking layer, a photoresist material or any other -polymer. m addition, the passivation layer 500 can be a pH -insensitive layer covering an ISF.ET. Example of pB-aiscnsitive layers include silanes, SA s, buffered hydrogels, PVC, parylene, poly ACE, or a combination thereof

j0146{ Figure 5B illustrates a side view of another embodiment of the substrate 1 12 having the active seasor 120, the control sensor .122, and the on-chip reference electrode 41 disposed oa the substrate 112, As shown in Figure 5B, the on-chip reference electrode 416 can be disposed or located ia between the active seasor 120 and the control sensor 122,

[0147} Figure 6A illustrates a side view of an embodiment of the active seasor 120 and the co trol seasor 122 each haviag an extended gate 600. The extended gate 600 can be an extension of the gate dielectric layer 412.

|01481 Figure 6B illustrates a side view of another embodiment of the acti ve sensor .120 and the control sensor 122 each having the extended gate 600 and an on-chip reference electrode 416 adjacent to the active sensor 120. As shown in Figures 6A and 6B, only the extended gate is exposed to the liquid. The extended gate can interact with particles in the solution. The extended gate can reduce the amount of material needed to make the active seasor 120.

|0I45>| Figure 7 illustrates an embodiment of the system 100 fabricated or designed as a disposable strip 700. The disposable strip 700 can comprise a number of active sensors 120 and control sensors 1.22 and an analyzer 1 18 disposed on a strip substrate such as the substrate 112. In one embodimeat, sample effluent 134 resulting from step I E or step ID depicted in Figure 1 can be introduced to one end of the disposable strip 700 and the other end of the disposabie strip 700 can be electrically coupled to or fed into the reader 114. In another embodiment, a fluid sample 124 can be introduced to one end of the disposabie strip 700 as shown ia step 2 A of Figure 2 and sample effluent 134 can flow to the active sensors 120, the control sensors 122 , or a combination thereof on the disposable strip 700, Although not shown in Figure 7, substrate wells 200 such as the active wells 206 and the control well 208 of Figure 2 can be disposed on the strip substrate upstream from the sensors 1 16. The reader 114 can then assess the susceptibility of a microorganism 102 hi the fluid sample 124 to the anti-infective KM introduced to or coated on the disposabie strip 700.

fOlSOj Figure 8 illustrates one embodiment of the analyzer 118 and the reader 114 processing signals outputted by the active sensor 120 and the control sensor 122. 7 ^' he analyzer 1 18, the reader 1 14, or a combination thereof can monitor the electrical

characteristic 800 of the sensors i 16 including the active sensor 120, the control sensor 122, or a combination thereof |01511 The active sensor .120 can. produce an active signal 802. The active signal 802 can be indicative of a change in the electrical characteristic 800 of the active sensor 120, For example, t he active signal 802 can be indicative of a change in the current, the voltage, the threshold voltage,, the capacitance, or the resistance of the active sensor .120. The active sensor .120 can exhibit a change in its electrical characteristic 800 due to a change in the solution characteristic 136 of a measured liquid 402 contacting or introduced to the active senso 120. For example, the active sensor 120 can exhibit a change in its electrical characteristic 800 due to a change in the solution characteristic 136 of the sample effluent 1.34 introduced to the active sensor 120, As a more specific example, the change in the solution characteristic 136 cao. be change in the concentration of an ion. or a change in the pH of the measured liquid 402 contacting or introduced to the active sensor 120.

[0152] The control sensor 122 can produce a control signal 804. The control signal can be indicative of a change in the electrical characteristic 809 of the control sensor 122, The control signal can be analyzed relative to the reference electrode. For example, the control signal 804 can be indicative of the change in the current, the voltage, the threshold voltage, the capacitance, or the resistance of the control sensor 1 2. Similar to the active sensor 120, the control sensor 1.22 can exhibit a change in its electrical characteristic 800 due to a change in the solution characteristic 136 of a measured liquid 402 contacting or introduced to the control sensor 122.

[0153] The analyzer 1 1 can receive as inputs the active signal 802 from the active sensor 1.20 and the control signal 804 from the control sensor .122 The analyzer 1.1 8 can produce a differential signal. 806. In one embodiment, the differential, signal 806 can be a difference between the active signal 802 and the control signal 804. The differential signal 806 or AS can also be indicative of a change in the electrical characteristic 800 of the active sensor .1 20 or the control sensor 122 or a difference between the electrical characteristic 800 of the active sensor 120 and the control sensor 122. The reader 1 14 and the analyzer 118 can also provide a feedback loop to control the active sensor 120,

[0154] The analyzer 1 18 can also convert the acti ve signal 802 and the control signal 804 from analog to digital. The differential signal 806 can be transmitted to the reader 114, and used to assess the susceptibility of the microorganism 102 in the fluid sample 124 to one or more anti-infectives 104, The reader 114 can also provide an output signal 808 assessing the susceptibility of the microorganism 102 to one or more anti-infectives 104. In one embodiment, the reader 1 14 can provide an output signal 808 indicating whether the microorganism 102 is -resistant or sensitive to an. ani -infective 104. In another embodiment, the reader 114 can provide an outpu t signal 80S indicating a level of susceptibility of the nxkroorgamsin 102 to one or more anti-infectives 104 such as susceptible, mildly susceptible, or resistant.

[0155] Figure 9 illustrates experimental results of experiments conducted using the methods and system 100 described herein. The graphs in Figure 9 show a change in the solution characteristic 136 of the measured liquid 402, such as the sample effluent 134, monitored by the system 100 at a specific point in time. In this case, the graphs in Figure 9 show the change in the solution characteristic .136 of the measured liquid 402 sixty (60) minutes after an and -infective 104 is introduced to the filter 1 1.0, the substrate wells 200, or a combination thereof comprising the microorganism 1 2,

[0156] As shown in Figure 9, the change in the solution characteristic 136 can be a change in the pH of the measured liquid 402. For example, the graphs in Figure 9 show the effects of various anti-infectives 104 on E. colt In this example, E. coir cm be one of the microorganisms 102 present in the fluid sample 124 applied or introduced to the system 100. As shown in Figure 9, a change in the solution characteristic 136, such as a change in itie pH, can indicate resistance of the microorganism 102 to the anti-infective 104 while a lack of a change or an insignificant change in the solution characteristic 136 can indicate a susceptibility of the microorganism 1.02 to the anti-infective 104. An insignificant change in the solution characteristic 136 can be a change below a statistically significant percentage or threshold value.

[0157 J For example, one of the graphs shows the effects of the anti-infective i 04 nitrofurantoin on the pH of the measured liquid 402, such as the sample effluent 134, 0 minutes after E. coii from the fluid sample 124 is exposed to nitrofurantoin of various concentrations. As can he seen in the graph, the E. co!i in the fluid sample 124 can be resistant to approximately 1 pg rol of nitrofurantoin but can be susceptible when exposed to approximately 10 pg/mi of nitrofurantoin.

[0158] Also, for example, another one of the graphs shows the effects of the anti- infective ciprofloxacin on the pH of the measured liquid 402, such as the sample effluent 1.34, 60 minutes after E. coii from the fluid sample 124 is exposed to ciprofloxacin of various concentrations. This graph shows that the systems, devices, and methods disclosed herein can be used to determine the minima! inhibitory concentration (MIC) of an anti- infective on a microorganism. As can be seen in the graph, the E. coii. in the fluid sample .124 can be resistant to approximately 0.1 pg/m! of ciprofloxacin but can be susceptible when exposed to approximately 1 i of nitrofurantoin, in this case, I ugfad can be the

MIC of nitrofurantoin on the E, coii isolated from the fluid sample 124.

{0159J Figure 10 illustrates additional experimental results of experiments conducted using the methods and system .1 0 described herein. The graphs in Figure 10 show the effects of various anti-infectives 104 on the bacteria Staphylococcus saprophytics. In these examples, Staphylococcus saprophytics can be one of the microorganisms 1 2 present in the fluid sample 124 applied or introduced to the system 100.

{0160| For example, one of the graphs shows the effects of the anti-infective 104 ampic.il.1in on the pH of the measured liquid 402, such as the sample effluent 134, 60 minutes after Staphylococcus saprophyeic s from the fluid sample 124 is exposed to ampicillm of various concentrations. As can be seen in the graph, the Staphylococcus saprophytics in the fluid sample 124 can be resistant to ampiciiiin when up to 50 itg/ml of ampicillm is introduced to filters or wells comprising the microorganism 1 2.

(0161 j Also, for example, another one of the graphs shows the effects of the anti- infective nitrofurantoin on the pH of the measured liquid 402, such, as the sample effluent 134, 60 minutes after Staphylococcus saprophytics from the fluid sample 124 is exposed to nitrofurantoin of various concentrations. As can be seen in the graph, the

saprophytics in the fluid sample 1.24 can be resistant to approximately 1 μ ηΐ of nitrofurantoin but can be susceptible when exposed to concentrations higher than 1 fig/mi of nitrofurantoin.

{0162 j Figure 11 illustrates an. embodiment of a method 1 100 for detecting a susceptibility of a microorganism 1.02 to one or more anti-infeetives 104. The method .1 1 0 can include exposing a surface, such as the filter surface 126 or the substrate surface 202, eomprising the microorganism 1 2 with a first solution, such as the nutrient solution 130, in a step 1 1 2. The method 1100 can also include separating the first solution from the microorganism .102 after exposing the surface in a step 1104, The method 1 .100 can further include monitoring an electrical characteristic 800 of a sensor 1 16 upon introducing the first solution to the sensor 1 16 in a step 1 106. The method 1 100 can also include exposing; the surface eomprising the microorganism 102 with, a second solution, such as additional nutrient solution 130, wherein the second solution comprises an an ti -infective 104 in a step 11 8. The method 1100 can further include separating the second solution from the microorganism 102 after exposing the surface in a step 1 .1 10, The method 1100 can also include detecting any changes in. the electrical characteristic 800 of the sensor 11 after introducing the second solution to the sensor 116 in step 1 112. The method 1 100 can further include assessing (he susceptibility of the microorganism 102 to the auti -infective

104 using any detected changes the electrical characteristic 800 of the sensor 116 in a step 11 Ϊ 4.

|0J 63] Figure 12 illustrates another method ! 200 for detecting a susceptibility of a microorganism 102 to one or more anti-infectives .104. The method 1200 can include exposing a surface, such as the filter surface 1 6 or the substrate surface 202, comprising the microorganism 102 with a first, solution, such as the nutrient solution 130, in a step 1202. The method 1200 can also include separating the first solution from the

microorganism i.02 after exposing the surface in a step 1204. The method 1200 can further include monitoring a first electrical characteristic of a first sensor, such as the control sensor .122, upon introducing the first solution to the first sensor in a step 1206. The method 1200 can also include exposing the surface comprising the microorganism 102 with second solution, such as additional nutrient solution 130, wherein the second solution comprises an anti-infective 104 in a step 1208, The method 1200 can further include separating the second solution from the microorganism 102 after exposing the surface in a step 1210, The method 1200 can also include monitoring a second electrical characteristic of a second sensor, such as the act ive sensor 120, after introducing the second solution to the second sensor in a step 121.2. The method. 1 00 can further include

comparing the first electrical characteristic and the second electrical characteristic to assess the susceptibility of the microorganism 102 to the anti-infective 104 in a step 1214.

{(il64j Figure 1.3 illustrates another method 1.300 for detecting a susceptibility of a microorganism 102 to one or more anti-infectives 104. The method 1300 can include exposing a filter 1 .1 comprising a microorganism 102 to a first solution, such a the nutrient solution 130 in a step 1302. The method 1300 can also include incubating the filter .1 10 comprising the microorganism 1 2 and the first solution in a step 1304. The method .1300 can also include separating the first solution from the microorganism 1 2 after incubating the filter 1.10 in a step 1306. The method 1300 can also include monitoring a first, solution characteristic of the first solution using sensor or sensor device 300, such as an ISFET sensor, in a step .1308. The method 1300 can also include exposing the filter 110 comprising the microorganism .1 2 to a second solution, wherein the second solution comprises an anti-infective 1 4 in a step 1310, The method 1300 can also include incubating the filter 11 comprising the microorganism. 102 and the second solution in a step 1312. The method 1300 can also include separating the second solution from the microorganism 102 after incubating the filter 1 10 in a step 1314. The method 1300 can also include monitoring a second solution characteristic of the second solution using the sensor 116 in a step 1316. The method 1300 can also include comparing the first solution characteristic and the second solution characteristic to assess the susceptibility of the microorganism 1 2 to the anti-infeeti ve 104 in a step i 318.

[0165] Figure .14 illustrates another method .1400 for detecting a susceptibility of a microorganism 1 2 to one or more anti-infectives 1 4. The method 1400 can include temporarily exposing a solution, such as the nutrient solution 130, to the microorganism 102, wherein the solution comprises an anti-infective 104 in a step 1402, The method 1 00 can also include providing a sensor 1 16 in fluid communication with the solution after the solution is separated from the microorganism. 1 2, wherein the sensor 1 6 comprises an electrical characteristic 800 in a step 1404. The method 1 00 can also include monitoring the sensor 116 for a change to the electrical characteristic 800 of the sensor 1 16 after providing the sensor 1 16 in fluid communication with the solution in a step 1406, The method 1400 can also include providing an indica tion of the susceptibility of the microorganism 102 to the anti -infective 1 4 upon a failure to detect the change to the electrical characteristic 8 of the sensor 1 16 in a step 1 08,

{0.166} Figure 5 illustrates another method 500 for detecting a susceptibility of a microorganism 102 to one or more anti- infectives 104·. The method 1500 can include delivering a first solution to a surtace, such as the filter surface 126 or the substrate surface 202, wherein the first solution does not contain an anti-infective 104 and wherein a microorganism 102 is located on the surface in a step 1.502. The method 1500 can also include separating the first solution from the microorganism 102 and the surface in a step 1504. The method 1500 can further include fluid!y coupling a sensor 1 16 with the first solution in a step 1506, The method 1500 can also include monitoring an electrical characteristic 800 of the sensor 11 while the sensor ! 16 is fluidly coupled to the first solution in a step 1508. The method 1500 can further include delivering second solution to the surface, where the second solution comprises the anti- infective 104 in a step 1 10. The method 1500 can also include separating the second solution from the microorganism 102 and the surface in a step 1512. The method 1 00 can further include monitoring the sensor 11 for change in the electrical characteristic 800 while the sensor 116 is fluidly coupled to the second solution to assess the susceptibility of the microorganism 1 2 to the anti-infective 1 4 in a step 1514.

{ 0167} Figure .16 illustrates another method .1600 for detecting a susceptibility of a microorganism 1 2 to one or more anti- infectives 104. The method 1600 can include introducing a fluid sample comprising the microorganism 102 to a first surface and a second surface in a step 1602. The method 1600 can also include exposing the first surface comprising the microorganism 102 to a first solution in a step 1604. The method 1600 can also include exposing tie second surface comprising t e microorganism 102 to a second solution, wherein the second solution comprise an anti-infective 104 in a step 1606. The method 1600 can also include separating the first solution from the first surface after exposing the first surface to the first solution in a step 1608. The method .5600 can also include separating the second solution from the second surface after exposing the second surface to the second solution in a step 1 10. The method 1600 can also include moui toring a first electrical characteristic of a sensor 1.16 upon introducing the first solution to the sensor .1 16 in a step 161 2. The method 1600 can also include monitoring second electrical characteristic of the sensor 116 after introducing the second solution to the sensor 1 1 in a step 1614. The method 1 00 can also include comparing the first electrical characteristic and the second electrical characteristic to assess the susceptibility of the microorganism 1 2 to the anti -infective 104.

jO.M } Eac of the individual variations or embodiments described and illustrated herein has discrete components and features which may be readil separated from or combined with the features of any of the other variations or embodiments. Modifications may be made to adapt a particular situation, material composition of matter, process, process act(s) or step(s) to the objective(s), spirit or scope of the present invention.

{01.69J Methods recited herein may be carried out in any order of the recited e vents that is logically possible, as well as the recited order of events. For example, the flowcharts or process flows depicted in the figures do not require the particular order shown to achieve the desired result. Moreover, additional steps or operations may he provided or steps or operations may be eliminated to achieve the desired result,

|0170] It will be understood by one of ordinary skill in the art that all or a portion of the methods disclosed herein may be embodied in a non-transitory machine readable or accessible medium comprising instructions readable or executable by a processor or processing unit of a computing device or other type of machine.

f0171 j Furthermore, where a range of values is provided, every intervening value between the upper and lower limit of thai range and any other stated or intervening value in that stated range is encompassed within the invention. Also, any optional feature of the inventive variations described may be set forth mid claimed independently, or in

combination with any one or more of the features described herein. |0172| All existing subject matter mentioned herein (e.g., publications, patents, patent applications and hardware) is incorporated by reference herein in its entiret except insofar as the subject matter may conflict with that, of the present invention (in which case what is present herein shall prevail). The referenced items are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such material by virtite of prior invention.

{01?J| Reference to a singular item, includes the possibility that there are plural of the same items present. More specifically, as used herein and in the appended claims, the singular forms "a," "an,' ^' "said" and "the" include plural referents unless the context clearly dictates otherwise. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as "solely," "only" and the like in connection with the recitation of claim elements, or use of a "negative" limitation. Unless defined otherwise, ail technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

j0174| This disclosure is not intended to be limited to the scope of the particular forms set forth, but is intended to co ver alternatives, modifications, and equivalents of the variations or embodiments described herein. Further, the scope of the disclosure fully encompasses other variations or embodiments that may become obvious to those skilled in the art in view of this disclosure. The scope of the present invention is limited only by the appended claims.