Field of the invention

The present invention relates to methods and systems for biological, biochemical or chemical sensing and/or detecting of particles. More particularly, the present invention relates to methods for label-free detection of particles using flow in a container and to corresponding devices and systems.

Background of the invention

Label-free techniques such as silicon photonic microring resonator sensors attempt to overcome the stability and reliability problems of biosensors relying on the detection of labeled molecules. While labeled detection methods can be sensitive down to a single molecule, labels can structurally and functionally alter the assay and the labeling process is labor intensive and costly. Quantification is difficult since the bias label intensity level is dependent on all working conditions. Moreover a labeled assay can only be performed in an 'end-point' fashion so that no kinetic information on the biomolecular interaction can be obtained. In practice, label-based assays require a high degree of development to assure that the label does not block an important active site on the tagged molecule or modify the molecular conformation.

Due to these considerations, there has been a drive to reduce assay cost and complexity while providing more quantitative information with high throughput. Label-free detection is a solution to this and involves a transducer element that directly measures some physical property of the biological compound. Such a transducer element may comprise an affinity-based biosensor whereby a so-called 'receptor' or 'ligand' is attached to the surface of the sensor, which responds to the affinity interaction of the receptor with the analyte of interest. The receptor molecule can be an antibody, receptor protein or DNA. The formation of complexes can thus be monitored continuously and many interactions can be followed simultaneously. This real-time data results in information on the kinetics of the reaction as well as on the concentration of the antibodies in the sample.

Optical label-free biosensors have received considerable attention over the past years. The key behind optical biosensors' ability to detect biological analytes is that they are able to translate changes in the propagation speed of light into a quantifiable signal proportional to the amount of biological material present on the sensor surface.

Label-free biosensing with silicon nanophotonic microring resonator sensors has proven to be an excellent sensing technique for achieving high-throughput and high sensitivity, comparing favorably with other labeled and label-free sensing techniques. However, as in any biosensing platform, silicon nanophotonic microring resonator sensors require a fluidic component which allows the continuous delivery of the sample to the sensor surface. This is the big disadvantage of this platform since this type of microfluidic system is very much removed from the daily practice in e.g. hospital labs, which still relies to a large degree on platforms like 96-well microtiter plates, or reaction tubes. Summary of the invention

It is an object of embodiments of the present invention to provide good and sensitive detection and/or quantification of biological, chemical or biochemical targets in a medium.

It is an advantage of embodiments of the present invention that label-free biosensing devices can be provided which can be manufactured more easily.

It is an advantage of embodiments of the present invention that a method and device can be provided that can be used in a lab-compatible reaction tube platform, such as a reaction tube or micro titer plate.

The above objectives are accomplished by a device and method according to the present invention.

In a first aspect, embodiments of the present invention relate to a sensing device for sensing a biological, chemical, biomimic or biochemical target analyte in a medium. In embodiments of the present invention the sensing device comprises a container for holding the medium and a sensor attached to at least part of the container in such a way that there is a contact interface between the inside of the container and at least part of the sensor, when the medium is held in the container. The at least part of the sensor being in contact with the inside of the container comprises a transducer element having at least one characteristic parameter. The sensing device according to embodiments of the present invention further comprises flow creating means for creating a flow of the medium over the transducer element, thereby creating a change of the characteristic parameter upon occurrence or variation, e.g. presence, of the target analyte in the medium.

The flow creating means may be a flow through means allowing the medium to flow through the container. In embodiments of the present invention the flow creating means may comprises - besides a filling opening - at least one container hole in the container. The latter will allow that the medium easily can flow through the container.

In embodiments of the present invention at least part of the sensor may be in contact with the opening of the container hole. The at least part of the sensor being in contact with the opening of the container hole may comprise at least one sensor hole. The at least one sensor hole and the at least one container hole may be arranged, e.g. aligned, in such a way that they form at least one flow through channel, also referred to as perforation extending from top to bottom, through the sensing device through which the medium can exit or enter, e.g. thereby flowing over an area of the sensor around the sensor hole and flowing through the sensor and exiting or entering the container. The container hole and the sensor hole may in this way drain the medium out of the container and form the flow creating means, creating a flow over the transducer element. The transducer element may be positioned in the area around the sensor hole where the flow is created. The transducer element may be positioned such that the distance of the at least one transducer element and at least one sensor hole is less than 5 times the diameter of the sensor hole, e.g. less than 3 times the diameter of the sensor hole or e.g. less than 2 times the diameter of the sensor hole. The diameter of the sensor hole may be defined as the average diameter of the at least one sensor hole closest to the at least one transducer element.

In embodiments of the present invention the sensor and/or the transducer element may be part of a photonic integrated circuit. The transducer element may be a photonic filter element, but is not limited thereto.

The container may be any of a reaction tube or a micro titer plate.

In embodiments of the present invention the transducer element may comprise a functionalized sensing surface for binding with the target analyte. Functionalisation is well known in the art and is therefore not described in more detail in the present application.

The sensing device may thus be a flow through system.

The sensing device may be a label-free sensing device, allowing sensing under dynamic conditions of the medium in a label-free manner.

The flow creating means may also comprise or may co-operate with a flow inducing means such as any of a pumping system or an electrophoresis system or any other suitable system allowing to induce flow of the medium, i.e. to induce dynamic conditions of the medium. Such flow inducing means thus also may be integrated in the sensor and/or the container. In embodiments of the present invention the flow creating means thus may refer to the sensor holes and/or container holes allowing the flow, whereas the flow inducing means may refer to the flow inducing means. Alternatively, the flow inducing means may be considered as part of the flow creating means.

The flow creating means can in some embodiments be adapted for internally creating flow in the container without providing a flow through system. The flow in the container may thus create a flow of the medium over the transducer element.

The flow creating means may be a stirring or mixing means positioned in the container.

The sensing device may be a consumable, e.g. a one-time-use only device, having the advantage of avoiding cross-contamination and/or avoiding the need for cleaning of the device.

In a second aspect, the present invention also relates to a detection system for detecting a biological, chemical, biomimic or biochemical target analyte in a medium, the detection system comprising

a sensing device holder for holding a sensing device as described above, and

an excitation source and/or detector configured with respect to the sensing device holder for coupling with the transducer element of the sensor in the container of the sensing device, when the sensing device is positioned in the sensing device holder.

When the transducer element is an optical element - e.g. photonics element - the excitation source and/or the detector may be configured such that radiation is coupled to the sensing device in the sensor in the container and/or may be configured such that radiation is coupled from the sensing device after interaction with the medium for detecting and analyzing signals.

The detection system furthermore may comprise a flow inducing means - in some embodiments not integrated in the sensing device but in the detection system - co-operating with the flow creating means of the sensing device for inducing a flow of the medium over the transducer element.

The flow inducing means may be a pumping means arranged for pumping the medium through the container of the sensing device.

The sensing device holder may comprise a chuck for positioning and holding the sensing device accurately with respect to the remaining components of the detection system. The chuck may be vacuum based. The holder may be adapted for aligning the sensing device with the flow inducing means as well as with other components of the detection system, such as for example the excitation source and/or the detector.

In a third aspect, the present invention relates to a method for sensing a biological, chemical, biomimic or biochemical target analyte in a medium. It comprises the steps of

obtaining a sensing device comprising a container for holding the medium and a sensor attached to at least part of the container, at least part of the sensor comprising a transducer element having at least one characteristic parameter

providing a medium in the container and creating in the container a flow of the medium over the transducer element, thereby creating a change of the characteristic parameter upon occurrence or variation of the target analyte in the medium, and

sensing the change of the characteristic parameter for deriving therefrom a presence or variation of the biological, chemical, biomimic or biochemical target analyte in the medium.

The obtained sensing device may be a consumable.

In some embodiments, the method may in addition or alternatively comprise the steps of:

- providing a container for holding the medium

- providing a sensor comprising a transducer element having at least one characteristic parameter

- attaching the sensor to at least part of the container in such a way that there is a contact interface between the medium and the transducer element

- creating a flow of the medium over the transducer element, thereby creating a change of the characteristic parameter upon presence of the target analyte in the medium.

Creating a flow of the medium over the transducer element may comprise the steps of creating at least one container hole in the container, creating at least one sensor hole in the sensor, attaching the sensor to the container in such a way that at least one perforation is formed by the at least one container hole and sensor hole through which the medium can exit or enter both the container and the sensor.

The at least one perforation may in this way create a flow in an area around the sensor hole. By providing a transducer element in the area where the flow is created, the flow may induce a change of the characteristic parameter of the transducer element upon sensing of target analytes in the medium by the transducer element, for instance upon binding of target analytes to the transducer element.

In one aspect, the present invention also comprises a method for manufacturing a sensing device, the method comprising

- obtaining a container for holding the medium,

- obtaining a sensor comprising a transducer element having at least one characteristic parameter,

- creating at least one sensor hole in the sensor and creating at least one container hole in the container so that, upon attaching the sensor to the container, at least one flow through channel is created allowing flow of the medium through the container, the at least one sensor hole in the sensor being positioned with respect to the transducer element such that the flow of the medium through the container induces a flow of the medium over the transducer element.

The method also may comprise attaching the sensor to the container.

Creating at least one sensor hole comprises inducing the sensor hole in the sensor through laser processing, such as for example laser ablation.

Particular and preferred aspects of the invention are set out in the accompanying independent and dependent claims. Features from the dependent claims may be combined with features of the independent claims and with features of other dependent or independent claims as appropriate and not merely as explicitly set out in the claims.

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter.

The drawings are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn on scale for illustrative purposes.

Any reference signs in the claims shall not be construed as limiting the scope.

In the different drawings, the same reference signs refer to the same or analogous elements.

Brief description of the drawings

FIG. 1 illustrates a chip layout as can be used according to an embodiment of the present invention. At the top side, a chip layout top view is shown, whereas at the bottom side a side view is shown in relationship to the irradiation beam and the detector.

FIG. 2 schematically illustrates a three dimensional representation of an example of a device according to an embodiment of the present invention, as well as a layout indicating the sensor holes.

FIG. 3 shows a simulation of a water-based fluid flow in an exemplary device structure, as can be obtained in an embodiment of the present invention. Streamlines in black in the middle confirm the existence of a flow in the vicinity of the apertures. FIG. 4 illustrates a microscope picture of the array of photonic sensors accompanied by an array of perforations next to them, as can be used in an embodiment of the present invention. Each perforation will create a flow in its closest sensor.

FIG. 5 illustrates a silicon photonic chip with the array of sensors and the embedded microfluidic system incorporated in the bottom of a reaction tube, according to an embodiment of the present invention.

FIG. 6. and FIG. 7 illustrate an elevated side view and a cross-sectional view of a sensing device mounted in a sensing system according to an embodiment of the present invention.

FIG. 8. illustrates the optical registration of three different steps of a bioassay, thus illustrating features of an embodiment according to the present invention.

The drawings are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn on scale for illustrative purposes.

Any reference signs in the claims shall not be construed as limiting the scope.

In the different drawings, the same reference signs refer to the same or analogous elements.

Detailed description of illustrative embodiments

The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn on scale for illustrative purposes. The dimensions and the relative dimensions do not correspond to actual reductions to practice of the invention.

Furthermore, the terms first, second and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

Moreover, the terms top, under and the like in the description and the claims are used for descriptive purposes and not necessarily for describing relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other orientations than described or illustrated herein.

It is to be noticed that the term "comprising", used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression "a device comprising means A and B" should not be limited to devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B.

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this invention, in one or more embodiments.

Similarly it should be appreciated that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the invention and aiding in the understanding of one or more of the various inventive aspects. This method of invention, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

Where in embodiments of the present application reference is made to a photonics integrated circuit (PIC), this may refer to a variety of forms and material systems such as for example low-index contrast waveguide platforms (e.g. polymer waveguides, glass/silica waveguides, Al _x Gaj. _x As waveguides, xGaj.xAS _y Pj. _y waveguides), high-index contrast waveguides (e.g. Silicon-on-lnsulator, semiconductor membranes), plasmonic waveguides (e.g. metal nano-particle arrays, metal layers), also called Photonic Lightwave circuits (PLC). A photonic integrated circuit comprises at least one integrated optical component, such as for example but not limiting to an integrated optical cavity, an integrated optical resonator, an integrated optical interferometer, an integrated optical coupler, a waveguide, a taper, a tuneable filter, a phase-shifter, a grating, a modulator, a detector, a source or a combination thereof. The optical components can be active or passive. The components can be integrated for example monolithically, heterogeneously or hybridly. Monolithical integration is the integration technology that uses a single processing flow to process the diverse components potentially using different materials, e.g. integrated germanium detectors in silicon photonics IC. Heterogeneous integration is the integration technology for which the components are processed in separate process flows, which are then integrated at die or wafer level, e.g. BCB bonding, wafer bonding, and other bonding schemes, 3D integration. Hybrid integration is the integration of components or materials on processed photonic integrated platforms, e.g. flip-chipping of detectors, bumping, gluing, wire bonding, co-packaging, etc.

The PIC may be an SOI (Silicon-on-lnsulator) material system, also referred to as silicon photonics system. However, the devices and methods of the present invention can be based on other material systems, such as for example ll l-V material systems, metallic layers, low index contrast material systems or a combination thereof.

The present invention relates to a sensing device for detecting a biological, chemical, biomimic or biochemical target analyte in a medium.

The sensing device according to the present invention may comprise a container for holding the medium and a sensor attached to at least a part of the container in such a way that there is a contact interface between the medium and at least part of the sensor.

The container may for instance comprise or be a reaction tube or microtiter plate, but is not limited thereto.

The sensor is attached to at least part of the container. The sensor may be provided partly or entirely to the inside of the container. The sensor may be provided partly or entirely to the outside of the container. In this last case, in order to create a contact interface between the medium and the sensor, a container hole is preferably made in the container and the sensor is positioned at least partly over this container hole in order to create a contact interface between the inside of the container and at least part of the sensor. The sensor may also be provided to the inside of the container and positioned at least partly over this container hole. The contact interface may then be formed by the top surface of the sensor or at least part of the top surface. The sensor may be attached to any surface of the container. The attachment can for instance be done to a side surface of the container or to a bottom surface of the container, the surfaces being inner or outer surfaces. When the sensor is attached to the inside of the container, the contact interface may be formed by the top surface of the sensor or at least part thereof. When the sensor is attached to the outside of the container, for instance over the opening of the container hole, the contact interface may be formed by a part of the sensor in contact with the opening of the container hole. The part of the sensor being in contact with the medium in the container, i.e. the part of the sensor having a contact interface with the container, comprises at least one transducer element having at least one characteristic parameter.

The transducer element may for instance be a mechanical, electrical or optical transducer element, with a corresponding characteristic parameter being for instance a resonance frequency, capacitance or resonance wavelength, but is not limited thereto.

The transducer element may for instance be an optical filter element, such as for instance an optical resonator element, such as for instance an optical ring resonator, but is not limited thereto.

The sensing device further comprises flow creating means for creating a flow of the medium over the transducer element. The flow may create a change of the characteristic parameter upon presence of the target analyte in the medium.

The flow creating means may for instance take the form of mechanical stirring means which are able to stir the medium inside the container, thereby creating a flow of the medium in the vicinity of the transducer element.

The flow creating means also may be at least one sensor hole in the part of the sensor being in contact with the medium in the container, i.e. the part of the sensor having a contact interface with the inside of the container, as such at least one sensor hole may allow the medium to flow through the sensor and may allow flow over the sensor, e.g. over the at least one transducer element. The sensor hole may be extending from top to bottom of the sensor. By configuring, e.g. aligning, a container hole and the sensor hole appropriately , for instance by positioning the top surface of the sensor hole over at least part of the bottom surface of the container where the container hole is provided or vice versa, at least one flow through channel, also referred to as perforation, can be created through which the medium can exit both the container and the sensor. The perforation may create a flow of the medium in an area around the at least one sensor hole. By positioning the at least one transducer element in such an area, the sensor hole may act as flow creating means creating a flow of the medium over the transducer element. The at least one container hole and/or sensor hole may have any shape considered suitable by the person skilled in the art, such as for instance, but not limited to circular, elliptical or rectangular shape. The dimensions of the container hole may have the same dimensions as those of the sensor hole, or may be larger or smaller.

The at least one container hole and/or the at least one sensor hole may have dimensions in the micrometer range, millimeter or centimeter range. In case the sensor is a photonic integrated circuit, the at least one sensor hole may have dimensions in the micrometer range, but is not limited thereto. Positioning the transducer element in an area around the sensor hole, may mean positioning the transducer element on a distance in the micrometer range away from the sensor hole, but is not limited thereto. The sensing device may comprise multiple transducer elements, each of the transducer elements having one or more corresponding sensor holes. One or more of the sensor holes may be aligned with the same container hole or with different container holes.

The position of the at least one transducer element is preferably chosen in such a way that the flow of the medium is created in the vicinity or in an area around the transducer element. The distance between the at least one transducer element and a sensor hole advantageously is less than 5 times, e.g. less than 3 times or less than 2 times the diameter of the sensor hole. The flow of the medium over the transducer element may create, upon presence of a target analyte in the medium, a change of the characteristic parameter of the transducer element. Such a change of the characteristic parameter may for instance be achieved because the transducer element comprises a sensor layer that binds with the target analyte, creating a shift of the characteristic parameter of the transducer element upon binding. In case the transducer element is for instance an optical resonating element, the optical resonator element may comprise a sensing layer that binds with the target analyte, thereby creating a shift of the resonance frequency of the optical resonator element upon binding. Functionalisation of sensor surfaces is well known to the person skilled in the art and is therefore not discussed in detail in the present description.

The device according to the present invention may further comprise a detection element for detecting a shift of the characteristic parameter, for instance upon binding of the target analyte onto a sensing surface of the transducer element.

The device may further comprise a processor for deriving information on the target analyte, said deriving being based on a detected shift of the characteristic parameter of the transducer element, for instance a shift of the resonance wavelength upon binding of target analytes onto a sensing surface of the transducer element. Such information about the target analyte may for instance include, but is not limited to information on the affinities and kinetics of the reaction as well as on the concentration of the antibodies in the sample.

The sensor may be part of a photonic integrated circuit, but is not limited thereto.

The detection element and/or processor may comprise a photonic integrated circuit compatible, integrated detection element and/or processor. It is an advantage of embodiments according to the present invention that integration of the sensor may result in a small footprint of the sensor.

Nevertheless, detection elements, processing components and excitation sources, e.g. when the at least one transducer element is an optical element, may also be part of a detection system, e.g. a read-out system for reading out sensing devices. In some embodiments, the sensing devices may only comprise passive components. The sensing devices can in some embodiments advantageously be used as consumables. In a second aspect, the present invention relates to a detection system for detecting a biological, chemical, biomimic or biochemical target analyte in a medium. The detection system thereby can be advantageously used for reading out sensing devices according to the first aspect. Advantageously, the active components for using and reading out sensing devices according to embodiments of the first aspect are comprised in the detection system, such that the sensing devices can be used as low price consumables. According to embodiments of the present invention, the detection system comprises a sensing device holder for holding a sensing device as described in the first aspect, and an excitation source and/or detector configured with respect to the sensing device holder for coupling with the transducer element of the sensor in the container of the sensing device, when the sensing device is positioned in the sensing device holder. Such configuration allows operation of the sensing device and accurate detection. The detection system furthermore may comprise a flow inducing means - in some embodiments not integrated in the sensing device but in the detection system - co-operating with the flow creating means of the sensing device for inducing a flow of the medium over the transducer element. The flow inducing means may be a pumping means arranged for pumping the medium through the container of the sensing device or any other means for inducing a flow. The flow inducing means, when part of the detection system, may be configured, e.g. using appropriate connection channels, with respect to the sensing device holder such that flow can be induced in the sensing device, when it is positioned in the sensing device holder. As indicated above, the sensing device holder may also comprise a chuck or table for positioning and holding the sensing device, which may have the shape of a reaction tube or a micro titer plate, accurately with respect to the remaining components of the detection system. Further features of the detection system may be partly or completely as described elsewhere in the description.

By way of illustration, a number of examples of sensing devices and detection systems of embodiments of the present invention will be provided further, the present invention not intended to be limited by specific details of such examples.

A photonic chip 100 was fabricated in SOI with 2-μηι buried oxide and a 220-nm silicon top layer with CMOS compatible 193-nm optical lithography and dry etching. The process was described by Selvaraja et al. in J. Lightwave Technol. 27 (2009) p 4076 - 4083. The resonators consist of 450-nm- wide single-mode waveguides, with 5-μηι bend radius, 2^m-long directional couplers, and a gap of 180 nm between the waveguides. The layout of the chip 100 is illustrated in Fig. 1, the upper drawing showing a chip layout top view and the lower drawing showing an elevated side view of the chip in relation to the incident irradiation beam and the detector. In the present example, four rings 110 are connected to one common input waveguide, each of them having a dedicated drop signal port. Three of these four ring series are placed independently next to the other. The three input waveguides are simultaneously addressed through vertical grating couplers 120 with a 2-mm-wide collimated beam, irradiation beam 130, from a tunable laser source. The output signals of the ring resonators 110 are near-vertically coupled to free space by means of integrated grating couplers 140 and are imaged with a detector 150, e.g. an infrared camera.

The shallow-etched gratings are, in the present example, part of the chip design and have a maximum coupling efficiency of 31 % at a wavelength of 1.55 μηι (40-nm 1-dB bandwidth) for a 10° off-vertical coupling angle. Because the bandwidth of the grating couplers is larger than the free spectral range of the resonators, the grating couplers do not limit the number of resonators placed in series. This optical setup allows very high alignment tolerances, measures the spectrum of all the ring resonators in parallel, and therefore presents no limitation for high-throughput sensing.

A TSL-510 tunable laser was in the present example used as a light source. The transmitted light was in the present example detected by an infrared camera. The input power was chosen so that the intensity of the resonance peaks corresponds to the pixel saturation level to obtain a maximum signal- to-noise ratio. An image is captured for every wavelength step and stores the maximum intensity values within each dedicated area that overlaps with an output grating coupler spot. Post processing consists of fitting the spectra to their theoretical shape and tracking these resonance peaks over time, but other post processing techniques also may be performed.

The photonic chip is integrated at the bottom of the reaction tube. The photonic chip comprises apertures that perforate the chip from the top to the bottom. The solution inserted in the tube will flow through these openings that work as exit channels, creating a flow, which will accelerate the detection process.

FIG. 2 shows a schematic illustration of an exemplary device with the embedded microfluidic system, wherein the sensor chip 100, is shown as well as a container 160. In the sensor chip 100, flow creation means being sensor holes 210 in the present case are indicated In the present example, the sensor chip may be a silicon-on-insulator chip with the photonic biosensors and the embedded microfluidic system. The chip is incorporated at the bottom of the reaction tube. In other embodiments, the chip may be incorporated in a well of a micro titer plate or a plurality of chips may be incorporated in a plurality of wells of a micro titer plate. The solution inserted in the tube will flow through these openings that work as exit channels, creating a flow, which will accelerate the detection process. The lay-out of the chip is such that an array of ring resonator sensors accompanied by an array of sensor holes, also referred to as perforations, next to them can be seen.

The perforations of the silicon-on-insulator chip are advantageously achieved by means of laser ablation. A Duetto laser source (Time-Bandwidth) was used to perform the perforations. 1000 ps- duration pulses were applied with a repetition rate of 50kHz at 355nm. The size of the openings and their position can be easily optimized by editing some parameters in the laser.

Some preliminary simulations were performed in order to confirm the existence of flow through the surface of the sensors. FIG. 3 shows the streamlines of a water-based fluid that goes through holes of 40 μηι diameter which simulate the perforations of the chip for one particular example. It can be seen that the sensor holes create a flow over the transducers. The position of the perforations may be in the near vicinity of the sensors to warrantee enough flow on their surface. In one example, the sensor hole may be positioned at 5 times the diameter of the hole or less, advantageously 3 times the diameter of the hole or less, for example 2 times the diameter of the hole or less. The diameter may for example be ΙΟΟμηι or less or for example 50μηι or less. FIG. 4 shows the perforations made in the chip. The array of sensors is accompanied by an array of perforations. Each perforation will create a flow for its closest sensor.

The photonic chip with the array of sensors and the embedded microfluidic system (being the number of perforations) described above is in some embodiments incorporated to the bottom of the reaction tube, once its original bottom is mechanically removed.

The attachment of the chip to the bottom of the tube is done permanently using UV curable glue which allows to align precisely the array of sensors in the center of the reaction tube. When the fluid under analysis will be inserted in the tube, this will be in contact with the sensors, and flow out through the apertures described above. FIG. 5 shows the picture of the final device.

To perform the experiments, in the present example the device was fixed on a tiny chuck by means of vacuum. This chuck also has a connection to a pump, where pressure can be applied positively or negatively, pushing or sucking any gas or fluid applied in a specific area of this chuck. The reaction tube with the photonic chip integrated at its bottom was carefully aligned, so the perforations of the chip coincide with this area. Any fluid in contact with the chip will flow through the holes and be sucked or pushed up again by the pump. FIG. 6 shows the device fixed on this chuck in elevated side view.

In the present example, grating couplers were used to couple the light from a tunable laser into the chip and couple it out to be detected by an infrared camera. Light is coupled in and out from the bottom of the chip, i.e. through the 750-μηι thick silicon substrate. The latter can be seen in the cross- sectional view of the sensing device mounted on the sensing system in FIG. 7. Silicon is considered practically transparent for the wavelength used (1.55 μηι). However, to reduce the scattering of the rough substrate surface and to facilitate the alignment of the laser beam and the detection of the light coupled out from the chip, a few simple processing steps were done in advance in the present example : the silicon substrate was thinned down to 300 μηι by chemical mechanical grinding and afterwards a chemical mechanical polishing step was performed in order to attain a smooth surface. .

By way of illustration and to show the capabilities of the combined device, the different steps were measured for an assay where the well-known high-affinity couple biotin-streptavidin was bound. The measurements were performed as follows:

Small volumes of different solutions were manually pipetted in the tube, and they were sucked out through the perforations of the bottom of the tube while being measured. The experiment consisted of three different steps. 1. The silanization of the surface: where a 2% solution of the aminosilane 3- Aminopropyl)triethoxysilane (APTES) was flowed preceded and followed by rinsing with ethanol.

2. The immobilization of biotin, where a solution 3mg/ml of biotin in Phosphate Buffered Saline PBS was flowed preceded and followed by rinsing with PBS pH 7.

3. The binding of streptavidin, where a solution of O. lmg/ml streptavidin in PBS was flowed preceded and followed by rinsing with PBS pH 7.

The time to perform each of these steps was less than one hour.

Fig. 8 shows three different graphs corresponding to each one of the steps of the assay. They show the evolution in time of the resonance wavelength shift of the ring resonators during the measurements with different solutions. The different lines each correspond to one sensor.

The association and disassociation of APTES in the sensor is easily quantifiable, as can be seen from FIG. 8. FIG. 8 at the top shows the silanization of the surface with APTES resulting in ethanol-APTES- ethanol. . FIG. 8 center shows the binding of biotin after flowing 3mg/ml solution of biotin in PBS and its disassociation when it is rinsed with PBS, resulting in immobilization of the biotin with formation of PBS-biotin-PBS . A shift of 30pm is measured when streptavidin in flowed through the chip proving the binding of this to the biotin. FIG. 8 at the bottom graph illustrates the binding of streptavidin to biotin resulting in the formation of PBS-streptavidin-PBS.

In one aspect, the present invention also relates to a method for sensing a biological, chemical, biomimic or biochemical target analyte in a medium. It comprises the steps of obtaining a sensing device comprising a container for holding the medium and a sensor attached to at least part of the container, at least part of the sensor comprising a transducer element having at least one characteristic parameter

providing a medium in the container and creating in the container a flow of the medium over the transducer element, thereby creating a change of the characteristic parameter upon occurrence or variation of the target analyte in the medium, and

sensing the change of the characteristic parameter for deriving therefrom a presence or variation of the biological, chemical, biomimic or biochemical target analyte in the medium. Other features and advantages may be as described elsewhere in this description. The method also may encompass method steps expressing the functionality of features and/or components of a sensing device according to the first aspect or a detection system according to the second aspect.

In yet another aspect, the present invention also relates to a method for manufacturing a sensing device, advantageously a sensing device according to an embodiments according to the first aspect. The manufacturing method thereby comprises obtaining a container for holding the medium and obtaining a sensor comprising a transducer element having at least one characteristic parameter. Obtaining a container and obtaining a sensor may comprise obtaining these components off the shelf. Alternatively, such components may be obtained by constructing them. Constructing a container, such as a reaction tube or a micro titer plate, may be performed according to techniques well known in the art. Constructing a sensor, e.g. a photonics sensor, also is known in the art and therefore not discussed in detail anymore. The method also comprises creating at least one sensor hole in the sensor and creating at least one container hole in the container so that, upon attaching the sensor to the container, at least one flow through channel is created allowing flow of the medium through the container. According to embodiments of the present invention, the at least one sensor hole in the sensor is being positioned with respect to the transducer element such that the flow of the medium through the container induces a flow of the medium over the transducer element. The latter can be obtained by limiting the distance between the transducer element and at least one sensor hole formed. In particular embodiments the sensor hole(s) may be formed at a distance from transducer less than 5 times, e.g. less than 3 times or less than 2 times the sensor hole diameter. The method also may comprise attaching the sensor to the container.

It has been found that in advantageous embodiments, the sensor hole(s) are generated through laser processing, e.g. laser ablation.