\mmi] This application claims priority to CIS . Provisional Application 61 /727,482 filed November 16, 2012, the complete isclosures- of which is incorporated herein by reference in Its entirety. 00 2] The inventio relates generally to hygroscopic wicks and, more particularly, to fiber wicks configured for transporting analyte fluids in assa devices,

[ 3] Various assay devices are known for use in. the home, office, clinic, hospital or doctor's surgery for providing an. analytical result which is rapid and which requites a minimal degree of skill and involvement by the user, Examples include test devices or assays for prepancy and fertile period (ovulation} determination.

(.0804] T pical assay devices comprise a housing, a reaction medium positioned in the housing, upon which, the assay chemistry occurs, and a wick for collecting the liquid to be assayed and rransi erring it to the reaction medium. In general the assay dev ce should merely require that a collection portion of the device be contacted with a sample (e.g., a urine sample for pregnancy testing), and thereafter no further user actions are required. The sample is carried from the collection portion to the reaction medium by the wick. Observation of changes to the reaction medium or a substrate carrying the reaction medium provide an analytical result..

Ideally, the analytical, resul shook! be Observable within a matter of minutes following sampling,

[00( 5] The actual analytic techniques used to- obtain the results typically determine the presence or absence of, and/or quantify the amount of various analyies in, tissues and fluids of organisms. Currently most diagnostic testing is done with blood, urine, fecal material, snliva, or tissue biopsy, Assay devices or collecting and reacting t es materials can be used for, inter die _* pregnancy ami ovulation tests, dmg-of- base tests, and infectious disease tests.

i [OOCNO One- problem, with standard assay devices-, particularly those designed for self-testing M the home,, is that the user may have difficulty determining whether enough of the analyte fluid or other material has be n rov ded to the sample collector. This ma he a particular problem with urine sampling devices because urine ma he relatively colorless. One approach. to solving this problem is to provide ^■ diagnostic assay devices with a color change indicator to signal that sufficient anai te-coin.am.ing liquid (e.g., urine, saliva, plasma) has been collected by the sample collector, in wick-based devices, the color change generally indicates that the vvicking component as bean "wetted out" with the analyte fluid,

[00071 !n such devices, however, the color change indication is based on the presence of a dye or colored substance that undergoes a change when wetted with water or other aqueous liquid. U.S. Patent Application No, 10/495,714 ( 1 Application"), for example, describes sample collectors having wicking components (termed "bibulous m m ers") that contain a dye that changes color as the result of a pH change. In some disclosed, exam les, a dry wick, contains the acid fo m of a -sensdive dye which, upon weiihig by the analyte-comaimng solution, experiences a pB change to more basic conditions, resulting in a color change. The color change is said to be distinctly visible to the eye so as to indicate sufficient, analyte s _. utioft is present to both conduct the diagnostic analysis and effect color change,

[00(1 ] Other compounds can undergo a. color change when wetted. For example, a commonly used indicator is cobalt chloride (GoC ), Anhydroos cobalt chloride is blue. When it bonds with two water molecules, (CoC12*2H20), it turns purple, Further hydration results in the pin:k hex aquaeobait(H) chloride complex Co(H20)6]Ci2, f OD$l These visual indications are the result of employing pbhsensiiive dye molecules, such as phlox me B or bromophenol blue, alon with pH altering reagents (acids or bases), or inorganic compounds. In either case, use of these chemical compounds may Interfere with, or otherwise alter, the analyte itself or the diagnostic assay. This may reduce the sensitivity of the assay or lead to ml e negative or false positive results.

[00010] Another approach to stnTicieoey indication is to permanently color the wicking ^• material, or provide it with a permanently colored mnrker and cover the wick or marker with an additional material that is substantially opaque when dry and light transmhtent when. wet. The above-mentioned 14 Application discloses the use of such materials- as sugar paste, e nitrocellulose membranes, and nylon microporous membranes o cover an acetate strip affixed, to the wicking material, Th s approach, however, may introduce additional uncertainty due to the separation of the cover, materia! from the wicking material. It also introduces significant complexity and cost to the production of the wick.

{00011] l ve present invention, provides a wick for use in determining sufficiency of an amount of anaiyte fluid provided to an ana!yte test section of an assay device,. The wick comprises & primary wick portion attached or attackable to the analyte test section so as to be in fluid communication therewith.. The primary wick portion has a receiving surface adapted for receiving the analyte fluid into a first area of the primary wick portion and is configured to draw the analyte fluid from die first area vo a second area of the primary wick portion. The wsek further comprise an indicator portion having a contrasting visual characteristic. The indicator portion Is disposed so that some or all of the indicator portion is co ered by at fe t a portion of die primary wick portion. The at least a portion of the primary wick portion comprises a first wicking material thai ec mes more light transrnissive when the first wicking materia! is wetted by the analyte fluid. The contrasting visual characteristic is viewable through die at least a portion, of die primary wick portion, only when the at least a portion of the primary wick portion is suffused by a predetermined amount of die at alyte fluid.

I i Mlli The invention can be more fully understood by reading the followin detailed description together with, the accompanying drawing, in which like reference indicators are used to designate like elements, and in which:

[00013] Figure 1 is a side view of an assa wick according to an embodiment of the invention;

[ )0014] Figure 2 is a side view of an assay wick itceording to an embodiment of the invention;

[00015] Figure 3 is a perspective view of an assay wick according to an embodiment of the invention;

[000161 Figure 4 is a section view of the assay wick of Figure 3 ; f;( Ml ^' i?j Figure S is a perspect ve view of an assay w ck accord ng to an embodiment of the invention;

|0CKtt.8J Figure 6 is n end view of the assay wick of Figure 5;

[000191 Figure 7 is a perspective view of m assay wiek according to an embodiment of the invention;

f 00O2-O] Figure 8 is a section view of the assay wick of Figure ?;

[00021] Figure 9 i$ a side view of an assay wick according to an embodiment of the invention; 0 22] figur 10 is a top view of an assay device incorporating a sufficiency indicator wick according to a embodiment of the uiveniion; and

[00023] Figu - 11 is a top iew of an assay device mcorporating a sufficiency indicator wick according to an embodiment of the invention,

[00024] ^' The present invention provides a visual sufficiency indicator system that does not contain color changing additives or- reagents thai change as the result of a chemical change or reaction. Embodiments of the present invention provide assay devices havin wicks in which die wicking material itself is configured so that it reveals a colored or indiei&mrnhtaoned indicator when it has absorbed a desired amount of anaiyte fluid, This is accomplished through the use of selected materials that tend to become more light transmitters! when wetted with the particular anaiyte fluid and. the tailoring of other physical ebamcierisues of the wiek so that the wick becomes sufficiently translucent to allow an underlying indicator layer to he viewed,

[00025] The tendency for ceitain materials suc as cotton cloth and paper to become more traosiucoih when wetted is well-known. These materials are formed from a multiplicity of cotton or cellulose fibers. While such libers are essentially transparent or translucent, their refraction index is significantly differen from that of aft. When light is presented to a shee formed from a multiplicity of these fibers, the disparity in refraction index cause a high degree of scatterin and reflection back to ard the source, The result is an appearance of an opaque, or slightly translucent white material. When wetted with water, however, these same material become more Sight rransniittenr. This is because their refractive indexes are similar to that of water. With less disparity in re ractive ind x, less scattering occurs and m r light asses through the material where i can be reflected back by art underlying surface, 1 0026] In an illustrious -embodiment of the invention, n assay wick has two primary components: (!) a primary wick material tha provides most or all of die wicking potential and (2) an cator material or layer positioned underneath or embedded within the primary wick material The primar wick material is formed from fibers that axe selected so that (a)the primary wick material adequately wicks a prede ermined anaiyte fluid and (b) visually obscures the indicator material when dry and visually re ^p eals the indicator material when wetted by a predetermined amount of the predetermined anaiyte fluid type. The indicator material is configured with a contrasting color or graphical indicium that is viewable through the primary wick material when the wick material is suffused with a sufficient amount of the anaiyte flui ,

£ 0027] As used herein the term anaiyte fluid means a fluid sample that is to be analyzed for the presence of one or more analytes in the fluid sample and/or to quantify the amount of. one or more anaiyi.es present in the fluid sample. The winking materials used in the various

embodiments of the present inversion need to provide rapid, controlled transport of anaiyte fluids. This can sometimes be accomplished by using fiber or otter materials that have a natural affinity for the anaiyte fluid of interest. In many i st nces, however, the material of the wick must be treated to enhance their affinity (or eliminate their phohidty) for the anai te fluid.

[00028] For the present application, ^' however, wicking capability is not the only consideration. The material must also exhibit the above-described effect in which ira.usluoency increases upon wetting with die anaiyte fluid. Th s not only limits the base material that can he used, it also restricts or eliminates the use of certain additives that would limit the inherent translucency of the material, ( 00291 With the above considerations in mind, various embodiments;; -of the invention will be described. With reference to Figure 1, an assay wick 100 according to an embodiment of the invention includes a primar wick layer ! K) and an indicator layer 120. The primary wick layer 1 10 has an upper or receiving surface 112, some or all of which may be pre ented for receiving an anaiyte fluid, and a lower surface 1 14. In some embodiments, the primary wick layer 110 may in addition or instead receive anaiyte fluid through an end surface 113 f om an external source or front another wick element. The primary wick iayer 110 is configured for receiving tire anaiyte fluid through the upper surface 112 and/or the end surface 1.13 and for tmnsponmg the anaiyte fluid from one portion of the primary wick layer 10 to another portion of the pr ma wick layer 110 that includes or is in fluid communication with an anaiyte test section 130. The indicator layer 120 is adhered or otherwise attached to the bottom surface 1 14 of the primary wick layer 11.0. As will be discussed in more detail, the primary wick layer 110 is. formed from a material that exhibits increased light transmittance when wetted by a particular anaiyte fluid,

000301 The indicator layer 120 may be formed from a materia! having a contrasting visual characteristic (i.e. , a distinct color or other appearance variation such as a pattern or indicium) relative to the visual appearance of the primary wick layer 110 and/or the anaiyte fluid,

Alternatively or in. addition, the indicator layer 120 may include or have applied to at least a portion of its upper surface an indicia layer 122. Some or all of the indicia layer .122 may be formed with a contrasting color selected to distinguish the indicia layer 122 from the primary wick layer 1 10 and e anaiyte fluid when me primary wick layer 110 is wetted with the anaiyte fluid. Further, some or ail of the indicia layer 1 2 may be provided with a graphical indicium formed using a color contrasting from, the primary wick layer 110 and the anaiyte fluid when the primary wick layer 110 is wetted with the anaiyte fluid. The graphical indicium may he any suitable graphic such as a logo, text, pattern, symbol or sign. In some eu odrmerits, t e indicium may include one or more instructions relating to dre use of the wick and/or the assay device in which the wick is incorporated. The indicator portion 120 may he a monolithic body or may be a layered or composite structure in which the uppermost layer has or carries the distinguishing color or indicia. Alternatively or in addition, the indicator portion 120 may be formed from materials that, like the material of the primary wick portion i 10, exhibit increased light trausrmttanee when wetted with the anaiyte fluid. In such embodiments, the indicator portion 120 may be loaded with a colored particulat or other material that pro ides the contrasting visual characteristic when, the indicator portion 120 is wetted.

[0 0 1] ^w i b reference to Figure 2, an assay wick 200 according to an embodimen of the invention includes a primary wick portton 210 having an upper wick layer 216. and a lower wick layer 18. An indicator layer 220 is disposed intermediate the upper and lower wick layers 216, 21 8. The upper wick layer 216 has an upper or receiving surface 212, some. or all of which may be presented for receivin an analyte fluid, aad a lower surface 214. In. some embodiments, the primary wick layer 210 may in addition or instead receive analyte fluid hrongh an end . s rfa e 21.3 from an external source or from another wick element, The upper wick layer 216 is configured fo receiving the analyte fluid through the upper surface 212 and/or the end surface 2.1.3 and for ira¾sportmg the analyte fluid to anodisr portion of the primary wick layer 210 that includes or is in fluid communication with an analyte test section 230> The indicator layer 220 is adhered o otherwise attacked to the irottorn surface- 214 of the primary wick layer 210. The lower wick layer 21.8 -ma ^' be adhered to the indicator layer 220 or, in some embodiments, may he adhered or otherwise attached to the upper wick layer 216 through or around the indicator layer 220, Alternatively, one or both of the indicator layer 220 and the lower wick l e 2!,¾ may be held in contact with the upper wick layer 216 and with one another by mechanical means such as asteners or a easing,

£00032] As in the previous embodiment, the indicator layer 220 may he formed from a material reaving a contrasting visual characteristic relative to die visual appearance of the upper wick layer 216 and/or the analyte fluid. Alternatively or in addition, the indicator layer 220 may include or have applied to at least a portion of its upper surface an indicia layer 222, Some or all of die indicia layer 222 may be formed with a contrasting color selected to distinguis the indicia layer 222 from the upper wick layer 216 and the analyte fluid when the upper wick layer 216 is wetted with the analyte fluid. Further, some or all of the indicia kyer 222 m y be provided with a graphical indicium fonned using a color contrasting from the upper wick kyer 216 and the analyte fluid when the upper wick layer 216 is wetted with the analyte fluid. The indicator portion 220 .may be a monolkhie body or may be ^, a layered or composite structure in which the uppermost layer ha or carries the. dis iuguishing color or indicia. Alternatively or i addition, the indicator portion 220 may be formed from materials that, like the material of the primary wick portion 210, exhibit increased light transmittance when wetted with the analyte fluid. In such embodiments, the indicator portion 220 may be loaded with a colored particulate or other material that provides the contrasting visual characteristic when the indicator portion 220 is wetted.

{00933J With reference to Figures 3 and 4, an assay wick 300 according to an embodiment of the invention includes a primary wick layer 310 and an indicator layer 320, The primary wick layer 310 has an upper or receiving surface _. 312,. some car all of w ich may be presented for receiving an analyte fluid, ami ^' a. lower surface 314, In s me embodiments, the primary wick layer 31.0 may m ddition or instead receive analyte fluid Orrough an end surface 3 J 3 from an e ternal source or fro another wick element. The primary wick layer 1.0 is configured for receiving the analyte fluid through the upper surface 312 and/or he end surface 313 and for transporting the analyte fluid from one portion of die primary wick layer 310 ui another portion of the primary wick layer 310 thai includes or is in fluid comnmHication With an analyte tes section 330.

[00034] The indicator layer 320 is embedded or encased entirely within the primary wick layer 310. The indicator layer 320 may be formed from a material having a contrasting isual characteristic relative to the visual appearance of the primary wick layer 3 0 and/or the analyte fluid. Alternatively or in additi n, the indicator layer 320 may include r have applied to at least a portion of its upper surface an indicia layer 322, Some or ail of the indici layer 322 may he formed with a eonrrasung color selected to distinguish the indicia layer 322 from t primary wick layer 31.0 and the analyte fluid when the primary wick layer 310 is wetted with the analyte fluid. Further, some or all of the indicia layer 322 may be provided with a graphical Indicium formed using a color contrasting from, the primary wick layer 3 0 and the analyte fluid whoa the primary wick layer 310 is wetted with, the analyte fluid. The indicator portion 320 may be a monolithic body or may be a layered or composite structure in winch the uppermost layer has or carries the dis uguishing color or Indicia, Alternatively or in addition, the indicator portion 320 may be formed f om materials that, like the material of the primary wick portion 310, exhibit increased light transmittance when wetted with the .analyte fluid, In such embodiments, the indicator portion 320 may be loaded with a colored particulate or othe material that provides the contrasting visual, characteristic when tire indicator portion 320 is wetted,

£0O( SJ With reference to Figures 5 and 6, an assay wick 400 according to an embodiment of the invention includes a cylindrical primary wick portion 410 surrounding an indicator portion 420. The primary wick portion 410 has an outer or receiving surface 412, some or ail of which may be presented for receiving an analyte fluid, and an Inner surface 414, In some

embodiments, the primary wick portion 410 may in additio or instead receive analyte fluid through, an end. surface 413 from an external source or from another wick element. The primary a wick portion 4.10 is fluid through the outer surface 412 and/or the end. surface 413 and for transporting the anaiyte fluid . from one portion of the primary wick portion 4.10 t:o another portion of the primary wick portion 410 that in ludes or is in fluid coni niheaiton with an anaiyte test section 430.

The indicator portion 420 may be form l as a circular cylinder, but may also be a prism or other shape, The outer surface: 422 of the indicator portion 420 is n contact with the inner surface 41 of the primary wiek portion 410, The indicator portion 420 may be formed, from a materia!, having a contracting viseai characteristic relative to the visual, appearance of the prim y wick portion. 410 and/or the .anaiy e fluid. Alternatively or in addition, the indicator portion 420 may include or have applied to at least a portion of its outer surface an indicia portion 422, Some or all of the indici portion 422 may be formed with a contrasting color selected to distinguish the indicia portion 422 from the primary wick portion 410 and the anaiyte fluid when he primary wick portion 410 is wetted witft the anaiyte fluid. Further, some or all of the indicia portion 422 may be provided ith a graphical indicium formed using a color contraating from the primary wiek portion 410 and. the anaiyte thud when the primar wick portion 410 is wetted with the anaiyte fluid. The indicator portion 420 may he a monolithic body or may he a layered or composite structure in which the radially outermost layer has o carries the distinguishing color or indicia. Alternatively or in addition, the indicator portion 420 may be formed from materials drat, like the material of the primary wick portion 41.0. exhibit increased light transmlttance when wetted with the anaiyte fluid. In such embodiments, the indicator portion 420 may be loaded with a colored particulate or other material that provides the contrasting visual characteristic when the indicator portion 420 is wetted,

[0003?] With reference to Figures _; 7 and 8, an assay wick 500 according to an embodiment of the mveatiou includes a cylindrical primary wick portion 510 having an outer wick portion 516 surrounding an indicator portion 520, The indicator portion 520 may be an annular cylinder or tube or may be a thin band or strip. In either ease, the indicator portion surrounds an inner wick portion 518. The primary wick portion 510 has an outer or receiving surface 512, some or all of which may he presented for receiving an anaiyte fluid, and an Inner surface 514- hi some embodiments, the primary wieik portion 510 may in addition or instead receive anaiyte fluid through, an end surface 513 front an. external source or from another wick element. The primary wick portion 510 is configured for receiving the analyte fluid through the outer surface 512 and/or the end surface 513 and for transporting the analyte- fluid from one portion of the primary wick portion 510 to■ another portion of the primary wick portion 510 that ^' includes or is m fluid communicati with .an amtlyte test section 530.

[0003S] The indicator portion. 520 has an outer surface 522 that is in contact with the inner surface 14 of die primary wick portion 310. The indicator portion 52 may he formed from a material having a distinct color or other appearance variation relative to feat of the primary wick .portion 510 and/or the analyse fluid. Alternatively or In addition, the indicator portion 520 may include or have applied to at east a portion of its outer surface an indicia portion 522. Some or all of the indicia portion 522 may be formed with a contrasting color selected to distinguish, the indicia portion 522 from the primary wick portion 510 and the analyte fluid when the primary wick portion 510 Is wetted with the analyte fluid. Further,, some or all of the indicia portion 522 may he provided with a graphical indicium formed using a. color contrasting from the primary wick portion 51 and the analyte fluid when the primary wick portion 510 is wetted with the analyte fluid. )0039] in the preceding embodiments, fee combination of the primary wick material and die ^• indicator material act as an analyte fluid sufficiency indicator. In each of these- embodiments, the sufficiency indicator is positioned in an area upstream of an analyte test section., it will he understood, however, that any of these sufficiency indicators could, alternatively or in addition, be placed downstream of an analyte test section. In the general s hematic illustration of

Figure 9, an assay wick 1000 has a fluid receiving portion 1040 configured tor receiving an. analyte fluid ferxrugh ^' a receiving surface 1042 and transporting the analyte fluid to an analyte test section 1030, The analyte test, section 1030 may have reagents disposed therein that react whh fee analyte fluid and provide a visual indication of a reaction result. The analyte test section 1030 is also configured to transport at least a portion of die analyte fluid to a sufficiency indicator 1 100. In the schematic illustration of Figure 9, the sufficiency indicator 1.100 has a primary wick layer 11 10 and an in ca or layer 1.120 that are similar in configuration, and operation to the primary wick layer 110 and indicator layer 120 of wick 100 in figure I.. ft. will he understood, however, that t e wick/indicator combinations of any of die preceding

embodiments could be used. 000 0;! ^" the advantage of placing a sidficiency indicator do nstream or the analyie lest seaso is thai it can b used to assure that a sufficient amount of analyie fluid, reached the anal vie test section,

[00041] Each of the fluid receiving portion 1040, analyie test section 1030, and at least the wink portion of the indicator i .1 0 m y b or include a ^■ wicking material. The wicking materia), of any of these three sections of the wick 1.0Q0 may he the same or different from die othe sections _* In some embodimen s , all three of the fluid receiving portion. 1040, the analyie test section 1030, and the wick portion of the sufficiency indicator j 100 comprise the same wicking material. In a particular embodiment, all three are formed as a single integral wick, element.

[00042] The wicking materials used in the various embodiments of me invention may be or Include any material that can sufficiently adsorb and wick an analyie fluid of interest. The winking material in sufficiency indicator portions must also exhibit enhanced traoslucency when wetted by the analyte fluid of interest. As has already been discussed, materials formed from certain natural fibers such as cellulose and cotton exhibit the .required enhanced transiucency wheu wetted with water-based^ analyte fluids, S.uch materials can also be used to tons wicks according to the Invention. It has been found, however, that materials formed f om synth ic polymer may he; preferable in many applications.

[00043] Plher-mase materials used in wicks of the invention may be woven or non-woven materials. In certain embodiments, the wicks of the invention may be bonded fiber _. structures comprising intetecrnnecting networks of highly dispersed continuous and/or staple fibers bonded to each other at paced apart, points of contact. As described in. U.S. Patent Mos. 5,607,766, 5,620,641, 5,63X082, 6,103,181 , 6 _* 330,883, and 6,840,692, the complete disclosure of each of which is incorporated herein by reference in Its entirety, such bonded fiber structures may he formed using a wide variety of fiber types and snanafnoturinf methods. Of particular utility .are structures made from fiber webs that are formed irrto srubstaatlaliy self-sustaining, th ee- dimensional porous components, The dispersed bonded fibers of these structures define tortuous passages through the structure that can provide very high surface areas and porosity, and may he formed in a variety of sizes and. shapes.

[00044] Many polymer materials that can be used to form the fibers used to make bonded fiber structures including but not limited to poiyoleflns, polyesters, po!ymethanes, and poiyamides, md copolymers thereof. Particular materials include polyetitylene, low dens ty polyethylene, polypropylene, polyethylene tereptit aie, noiybutylene terephthalate and nylon.

[00045] it will be tanlerstood, ho ver _* dial not all of &e above polymer materi ls will be suited for sufficiency indicators- to be used with a particular aualyte fluid. Same may not have a edaction index sufficiently close to that of die aualyte fluid. Others may simply noi be usable to wick the analyte fluid without the use of additives that could affect translucency. For example, hydrophobic materials (e.g., polypropylene) may not be usable in an assay wick, for a urine test withou a surfactant.

[Θ0Ι 4 1 The ideal fiber for use tu sufficiency indicators of the invention r* one thai is formed, at least hi part, from a polymer material that naturally has a refr action index close to that of tie anaiyie fluid of Interest and that can be used to form a. bonded fiber structure ha ing the desired fluid transport characteristics. Mo.a0c0mpor.ent fibers, bkomponent (or other nmUieonrponeni) fibers or combinations of both may he used. In bicomporient fibers, ai least one of the two fiber eooaponeo s (and preferably both) would have a refractive index close to that of the aualyte fluid, la particular embodiments, wick materials may he formed from, sheath/core bieomporrent fibers in which at least the sheath component and preferably bom. the sheath and the core components are formed from polymer materials exhibiting a refractive index close to that of the aualyte fluid.

[1 ⁾ 004?] Many assay wick test kits are configured for collection and testing of urine or saliva. Such wicks are described in detail in U.S. Pat Ho. 7,290,668, the complete disclosure. of which is incorporated here n by reference in its e tir y it Is highly desirable, particularly in home rest kits, to provide the user of these kits an immediate indication that a sufficient amount of urine or saliva has been provided. Accordingly, a sufficiency indicator according to the invention ust incorporate wick material, tha has an affinity for water and that exhibits increased translncency when wetted with water,

i- 0HO48] It has been found that structures formed from poiyoiefk fibers, generally, and fibers comprising polyethylene (PE) and polypropylene (PP), in particular, exhibit suitable enhanced transiueenny in water. Fibers formed from other polymers such as pol ethyleneterephthal ie (PET), polybutyiene terephthaiate (PST), and poiyarnides may also be usable. [00049] Bonded i er structures having both fee desrred wi.efc.uvg capability and tmns ceney behavior can be formed from PE raonocomponeni fibers. A particularly suitable bonded fiber structure, however, may be formed from sheam/oore bicomponent fibers having a PE sheath and a PP core. In such fibers, the surface energy and water compatibility is provided by the PE. sheath (typically treated with: additives ot .hydrop iiSk finishes), and the PP core enhances fee ffeef s structural capability. Both components exhibit the requisite riarrshicenc behavior, jlOOSO] hi some- embodiments of the in ent on, the primary wick layer portion and the indicator kyer/portion of mi assay wick suffi i ncy indicator may both be bonded fiber structures, in such embodiments, the primary wick layer/portion tnay he formed fkwn fibers (e<g., polyolefm. fibers) that exhibit the .required translucency behavior. The indicator layer/portion ma use the same fiber .materials, but it may, however, may be formed from othe fiber materials feat provide the desired flow characteristics. In either ease, the bonded fiber indicator Isyer/pofoon may be dyed or otherwise treated to be a contrasting color that would become visible only upon sufficient wettin of the primary wick layer/portion by the appropriate aualyte fluid.

[ ⁽ MMiSi] As an ahernati ve†,o surface indicia or coloring, some embodiments may have an indicator layer/portion (e.g.., a bonded fiber structure) that is configured to exhibit increased uansloceney upon wetting and tha is loaded with a colored particulate or other contrasting material that is revesled upon wetting of the indicator layer/portion. In such embodiments, the increased translucency of both, fee primary wick layer and the indicator layer upon wetting by the analyte fluid allows the contrasting material to be viewed. Similar contrasting materials could be added to some or all of the primary wick layer, which, in certain embodiments, could eliminate the need for a separate indicator layer.

[00852] As noted above, fee indicator layers of the invention may be formed from polymer fibers, and may, in particular, be porous, bonded fiber structures having similar or different materials and flow properties to/from the primary wick layer. The indicator layers of the hwention may also be formed from othe materials including, but not limited to, metal, foam (open or closed ceil), films, molded plastic, composites, and particulates. These materials may have a contrasting color throughout their structure or on single surface or they may be formed with contrasting topographical features. [00053] It will be -understood that the wick smtciures as d in the invention can be tailored to provide desired fluid characteristics. For fiber structures, this can be accomplished by- combination of fiber materia! selection, fiber diameter, and. porosity of the wick structure, It will farther be understood that the thickness of the wick structure (or the depth of/the indicator layer/material depending oa the embodiment) in the sofflcieney indicator portions of fee assay wicks of the invention will be dependent on the degree of iranskieeney of the material when wetted by the analyte fluid, This, in turm may fee dependent on the density of the wick structure and. the relative d fference .in refractive index between die wick material and die analyte fluid. Thus, it can be seen that the various wick material chataerensties can be tailored so as to optimise fluid flow characteristics and translneency for a given indicator -depth.

$0054] Any or all of these characteristics cars be adjusted to assur that the indicator layer/portion becomes visible only when an amount of analyte fluid su ficient to assure a desired reaction with the reagents of the analyte test section is present. Io some eases, it may fee desirable to include particular indicia on the indicator layer/portion, The wick structure and indicator depth could then be tailored so that die indici only become readable upon wetting by a sihlieient amount of analyte fluid.

100055] Any or all of the assay wicks of the inv ntion may be boused in a standard, assay device casing. Typically, such casings allow for selective exposure of the wick receiving surface and one or more windows for viewing a visual indication frorn the analyte reaction portion of the wick. For some wicks of the present invention, a window may also be provided to view the sufficiency indic tor portion of the wick j$0©5<»! The operation, of any of the assay wicks of the invention is straig orward. When an appropriate analyie .fluid is ^' introduced to the receiving surface of the wick, if Is transported through the receiving portion of the wick toward the analyte test section. In embodimerns where the sufficiency indicator is upstream of tire anal e test section, the analyte fluid is passed through the wieking portionfs ; of die sufficiency indicator to the analyte test section. In ernbadirnents where the sufficiency indicator portion of the wick is downstream of the analyte mi section, the analyte fluid is passed through the analyte test, section and into the wiefcin pordon(s) of the suiiaciexrey indicator section, hi cither c se, as die primary wiefcing

layer/portion of the sufficiency indicator is wetted by the analyte fluid, it will become more light tran mlttent (Le,, more translucent). Prior to itrnx uctiors of. the analyte fluid _* the rima wlcking layer/portion is essentially white or colorless. If the amount of analyte fluid is sufficient to fully infuse the p mar wieking layer/portion of the sufficiency indicator, the primary jekiog layer/portion will become sufficiently translucent that the contrasting color or indicia of the indicator layendponion can be observed, CK)057j The wicks of the invention ha ve a wide applicability and may be used in conjimetion with virtually an analyte fluid, including biological analytc fluids such as urine, plasma, serum, sweat, lachrymal fluid (tears), and saliva. Moreover, the wicks of the mvmtioa may be used in ssay devices for detectin n or more analvtes including, but not limited to. hormones such as huxnan chorionic gonadotropin (h.CG) frequently used as a marker for pregnancy, antigens, enz mes, antibodies to HIV, antibodies to HTLV, antibodies to Helicobacter pylori, antibodies to hepatitis, antibodies to measles, hepatitis antigens, antibodies to lerpotternes, antibodies to host or infeciions agents, cellular markers of pathology indudmg, but not limited toceardioiipin, lecithin, cholesterol iipopoiysaccari.de and sialic acid, antibodies to mumps, antibodies to rubella, cotini e, cocaine, benzoylocgonine, benzodizazpines, tetrahydrocannabinol, nicotine, et atioi theophylline, pbenytom, acetanrinopberj, lithium, diazepam, nortriptyline, secobarbital, phenobarbital, theophyHine, testosterone, estradiol, 1.7mydroxyprogesterone, progesterone, thyroxine, thyroid stimulation hormone, foHicle stimulating hormone, luteinizing hormone, transforming growth factor alpha, epidermal, growth factor, insulin-like growth facto ! and if grow h, hormone release inhibiting factor, IGA and s x hormone binding globulin; and other analytes mcitnliog glucose, cholesterol, caffeine,, cholesterol, corticosteroid binding globulin, PSA, or BHEA bmdmg glycoprotein,.

[CMHBS] As has been discussed, the sufficiency indicator wicks of the invention may be used in a variety of assay devices. Figures 10 and 11 depict two exemplary assay devices that could make use of these wicks, In Figure 10, an assay device 1200 has a housing 1250 in which is disposed an analyte test section 1230 that Is viewable mrough a window 1.252 in the housing 1250. The analyte test section- 1230 is in fluid communication with -a sufficiency indicator section 1201 comprising a primary wick portion 1210 and an indicator portion 1220, which may be configured according to any of the embodiments disclosed above. The primary wick, portion is also in fluid communication with an analyte receiving section 1240 having a receiving surface 1242, Analyre fluid received, by the rece ing section 1240 s wicked by the primary wick portion, to d e a ts! vie test section 1230 where it can be reacted with agents disposed there, The reaction may be viewed through the window 1252.. The indicator secti n 1201 is configured so thai: the indicator portion 1220 is concealed, by the primary wick portion 1210 unless or until the primary wick portion 1.210 has been wetted by a sufficient amount of analyte fluid. hen suffic entl suffused th analyte fluid, the contrasting characteristic of the indicator portion 1220 can be viewed through the primary wick portion 1210,

[00059! in the illustrated embo iment, some of the primary wick portion 1210 is disposed Inside the housing ,1250 and some is exposed outside the housing along with at least some of the indicator portion 1220 so thai the indicator portion 1220 can be viewed when the primary wrck portio is wetted. In an alternative embodiment, the entire indkaror section 1201. may be disposed, inside the b u in .1250, but positioned to be viewed through the window 1252 or through an additional window (not shown), it will be understood that the receiving surface 1242 may be a. surface of the primary wick portion 1210 or may be on a separate wick portion attached to or integrally formed with the primary wick portion 1.210. i i ½ ] In Figure 1 1 , an assay device 1300 has a housing 1350 in. which disposed an analyte test section 1330 that is viewable through a window 1352 in the housing 1350. A sufficiency indicator section 130 i is disposed within tire housing 1350 and in downstream fluid communication with the analyte test, section 1330, The indicator section 1 01 comprises a primary wick portion. 1.310 arid an indicator portion 1320, which may he configured according to any of the embodiments disclosed above. The analyte tost section 1 30 is in fluid

commmiicatiors. with aft analyte receiving section 1340 having a receiving surraee 1342. Anaiyte Held received by the receiving section 1340 is wicked to die analyte test section 1330 where it can he reacted with agents disposed there. The reaction may be viewed through the window 1352, The analyte fluid is also passed to the indicator section 1301. The indicator section 1301 is configured so that the indicator portion 1320 is concealed by the primary wick portion 1310 unles or mrb! the primary wick portion 1310 has been wetted by a sufficient amount of analyte fluid. When sufficiently suiTuserl with analyte fluid, the contrasting characteristic of die indicator portion 1320 can he viewed through the primary wick portion 1310 and the indow 1354.

1.6 f§tti !] It will be understood that many other assay device configurations are ossible. 00062] The preceding disclosure tias focused on the use of he indicator wick sections of tie mvendon as fluid sufficiency indicators. The wetted tramluc ucy behavior of the wick materials also allows embodiments of the inven ion to be used as indicators of a dry condition. For example, the indicator wick sections of the invention could fee used as end of-hre indicators for ai freshener devices such as those disclosed in. U.S. App, No. 12/099,942, filed April 9, 2008, the complete disclosure of which is incorporated herein by reference in its entirety. In sued an application, the indicator section would be incorporated into the air Freshener wick: with the characteristic of the primary wick portion being tailored to the air freshener fluid (the "anaiyte fluid"). Thu , the wlekmg material of the primary wick portion would be substantially transparent or translucent as long as the indicator section remained immersed m the air freshenet fluid. Once that fluid runs out, however, the primary- wick portion begins to dry out As i does, ii will become less and less light transr kteut (i.e., more opaque) until, the indicator portion/l er i obscured. This effect can he us d, for example, to make the wick appear the color of die indicator portion until -the fragrance fluid is gone, at which time the wick, turns colorless or white,

[ø€?ø©] While the foregoing illustrates and describes exemplary embodiments of this invention, ii is to he understood that tire invention is not limited to the construction disclosed herein. The mvention can be embodied in. other specific forms without departing from the spirit or essential attributes.