Multilayer adhesive fluid collection article containing capillary channels - Patents.com

Abstract

The present disclosure provides an article including an adhesive layer, a film layer bonded to the adhesive layer and having a microstructured surface including a plurality of capillary channels, and a cover layer disposed over the capillary channels and attached to the adhesive layer. The adhesive layer is hydrophobic and includes apertures for fluid (e.g., sweat) collection from the skin surface. The film layer also includes apertures that overlap the apertures in the adhesive layer and direct the collected fluid into the capillary channels in the microstructured surface, which has a hydrophilic surface. Optionally, at least one indicator chemistry can be present in the channels to facilitate optical (e.g., visual) determination of the total fluid volume and / or concentration of at least one analyte in the fluid as a function of time.

Description

[Background technology]

[0001] There is growing interest in collecting biometric data using body-worn sensors. A well-known example is activity trackers that use wrist-worn accelerometers to detect movement. An emerging field in wearable sensing is sweat monitoring using skin-interfaced microfluidic devices. Exemplary applications include determining sweat volume over time and measuring specific analytes in sweat by incorporating biosensors into the fluidic device. Determining volume or detecting specific analytes can be accomplished electrochemically, optically, or a combination of both. See, for example, International Application Publication No. 2019 / 023195 (Model et al.), U.S. Application Publication No. 2018 / 0303388 (Rao et al.), U.S. Application Publication No. 2018 / 0042585 (Heikenfeld et al.), and U.S. Application Publication No. 2019 / 0008448 (Begtrup et al.). There remains a need to provide articles that can collect fluids and provide information about the fluids when worn on the body. Summary of the Invention

[0002] In a first aspect, an article is provided. The article includes: a) an adhesive layer; b) a film layer bonded to the adhesive layer, the film layer having a microstructured surface including a plurality of capillary channels; and c) a cover layer disposed over the plurality of capillary channels of the film layer. More specifically, the adhesive layer has a first major surface and an opposite second major surface, and the adhesive layer defines a first aperture having at least one edge. The first major surface of the adhesive layer does not spontaneously wick when contacted with an aqueous fluid. The film layer has a first major surface and a second major surface, and the first major surface of the film layer is bonded to the first major surface of the adhesive layer. The film layer defines a second aperture disposed partially overlapping the first aperture. The second major surface of the film layer is a microstructured surface, and each of the plurality of capillary channels is in fluid communication with the second aperture and extends toward the periphery of the film layer. The surface of each of the capillary channels exhibits spontaneous wicking when contacted with aqueous fluids.

[0003] It has been discovered that articles according to at least certain embodiments of the present disclosure can provide a compact skin-interfacing device that provides consistent and uniform collection and transport of sweat.

[0004] The above summary of the present disclosure is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The following description more particularly exemplifies exemplary embodiments. In several places throughout this application, guidance is provided by listing examples, which examples can be used in various combinations. In each instance, the recited items serve only as a representative group and should not be interpreted as an exclusive list. [Brief explanation of the drawings]

[0005] [Figure 1A] 1 is a generalized exploded schematic view of an exemplary article. [Figure 1B] FIG. 1B is a generalized schematic diagram of an exemplary article according to FIG. 1A. [Figure 1C] FIG. 1C is a cross-sectional view of the article of FIG. 1B. [Figure 1D] 1 is a generalized schematic diagram of a portion of a film layer of an exemplary article. [Figure 1E] 1B is a generalized schematic cross-sectional view of another exemplary article according to FIG. 1A. [Figure 2A] FIG. 1 is a cross-sectional schematic diagram of a film having a microstructured surface in which capillary channels are defined by sidewalls that converge at the bottom of the capillary channels (eg, V-shaped). [Figure 2B] FIG. 1 is a cross-sectional schematic diagram of a film having a microstructured surface with capillary channels defined by sidewalls and a bottom wall therebetween. [Figure 3] FIG. 2 is a generalized schematic top view of another exemplary article. [Figure 4A] FIG. 10 is a generalized schematic top view of a further exemplary article according to Example 2 prior to filling with a fluid. [Figure 4B] FIG. 4B is a generalized schematic top view of the article of FIG. 4A after fluid filling has begun. [Figure 4C] FIG. 4B is a generalized schematic top view of the article of FIG. 4A as it continues to be filled with fluid. [Figure 4D] FIG. 4B is a generalized schematic top view of the article of FIG. 4A during further fluid filling. [Figure 5] FIG. 1 is a generalized schematic top view of an exemplary article including an opaque region and an observation window region. [Figure 6A] FIG. 2 is a generalized schematic top view of a further exemplary article. [Figure 6B] 1 is an SEM image of a portion of a capillary channel of an exemplary article having discontinuous regions on its surface.

[0006] The above-identified figures illustrate several embodiments of the present disclosure; however, other embodiments are also contemplated as noted herein. The figures are not necessarily drawn to scale. In all cases, this disclosure presents the invention by way of representation and not by way of limitation. DETAILED DESCRIPTION OF THE INVENTION

[0007] As used herein, the term "microreplication" means creating a microstructured surface through a process in which the features of the structured surface maintain individual feature fidelity during fabrication.

[0008] As used herein, the term "microstructure" encompasses both structures (i.e., features) that protrude above a major surface of the substrate and structures that are recessed below the major surface of the substrate. Combinations of protruding and recessed features are contemplated. Microstructure further means that the structure is a predetermined molded structure (e.g., obtained by molding a polymeric thermoplastic against a tooling surface that comprises the negative of the microstructure desired to be provided on the first major side of the substrate) having dimensions in the range of about 5 to about 3000 micrometers in at least two orthogonal directions. One of these orthogonal directions is often perpendicular to the plane of the substrate (e.g., along the z-axis), and thus this dimension can include, for example, a protruding height or a recessed depth.

[0009] As used herein, the term "capillary channel" refers to a passageway through which a fluid flows without the aid of an external force (e.g., pressure, gravity, vacuum, etc.).

[0010] As used herein, the "glass transition temperature" (T g The term T refers to the transition of a polymer from a glassy to a rubbery state and can be measured using Differential Scanning Calorimetry (DSC), for example, at a heating rate of 10°C per minute in a nitrogen stream. g When a reference is made to a T of the homopolymer of that monomer, g The homopolymer is T g The molecular weight must be high enough so that the T of the homopolymer reaches a limiting value. g It is understood that T increases with increasing molecular weight up to a limiting value.g It is understood that the DSC method is substantially free of moisture, residual monomers, solvents, and other contaminants that may affect the performance of the polymer. Suitable DSC and analytical methods are as described in Matsumoto, A. et al., J. Polym. Sci. A., Polym. Chem. 1993, 31, 2531-2539.

[0011] As used herein, the term "Vicat softening temperature" of a polymer refers to the determination of the softening point of a material that does not have a distinct melting point. It is interpreted as the temperature at which a test specimen is penetrated to a depth of 1 mm by a flat-tipped needle under a specified load.

[0012] As used herein, the term "hydrophilic" refers to a surface that is wetted by an aqueous solution, without describing whether the material absorbs the aqueous solution. "Wetting" means that the surface exhibits spontaneous wicking when contacted with an aqueous fluid. An aqueous fluid contains 50% or more water by volume. In some embodiments, a hydrophilic surface exhibits an advancing (maximum) water contact angle of less than 90°, preferably 45° or less.

[0013] As used herein, the term "hydrophobic" refers to a surface that does not spontaneously wick when contacted with aqueous fluids. In some embodiments, a hydrophobic surface exhibits an advancing water contact angle of 70° or greater, preferably 90° or greater.

[0014] As used herein, "curing" means hardening or partially hardening a composition by any mechanism, e.g., heat, light, radiation, electron beam, microwave, chemical reaction, or a combination thereof. As used herein, the term "hardenable" refers to a material that can be hardened or solidified, e.g., by heating to remove solvent, by heating to cause polymerization, chemical crosslinking, radiation-induced polymerization, crosslinking, etc. As used herein, "hardened" refers to a material or composition that has been hardened or partially hardened (e.g., polymerized or crosslinked) by curing.

[0015] As used herein, a polymer "film" is a polymer material in the form of a generally flat sheet that is sufficiently flexible and strong to be processed in a roll-to-roll manner. Roll-to-roll refers to a process in which the material is wound onto or unwound from a support and further processed in some manner. Examples of further processing include coating, slitting, die-cutting, and exposure to radiation. Polymer films can be produced in a variety of thicknesses, generally ranging from about 5 micrometers to 1000 micrometers.

[0016] As used herein, "thermoplastic" refers to a polymer that flows when heated sufficiently above its glass transition temperature and becomes solid when cooled. In contrast, "thermoset" refers to a polymer that becomes permanently hardened upon curing and does not flow when subsequently heated. Thermoset polymers are typically crosslinked polymers.

[0017] As used herein, "transparent" refers to a material (e.g., a layer) that has at least 50% transmittance, 70% transmittance, or optionally greater than 90% transmittance over at least the 400 nanometer (nm) to 700 nm portion of the visible light spectrum.

[0018] The words "preferred" and "preferably" refer to embodiments of the present disclosure that may provide certain benefits, under particular circumstances, although other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the present disclosure.

[0019] In this application, terms such as "a," "an," and "the" are not intended to refer only to a singular entity, but include general classes, specific examples of which may be used for illustration. The terms "a," "an," and "the" are used interchangeably with the term "at least one." The phrases "at least one of" and "including at least one of" following a list refer to any one of the items in the list and any combination of two or more items in the list.

[0020] As used herein, the term "or" is generally used in its ordinary sense, including "and / or," unless the content clearly dictates otherwise. The term "and / or" refers to one or all of the listed elements or a combination of any two or more of the listed elements.

[0021] Also, all numbers herein are intended to be modified by the term "about," and preferably by the term "exactly." As used herein, in connection with a measured quantity, the term "about" refers to the variation in the measured quantity that would be expected by one of ordinary skill in the art making the measurement and exercising a level of care commensurate with the purpose of the measurement and the precision of the measuring device used.

[0022] When used herein as a modifier to a characteristic or attribute, the term "generally," unless otherwise specified, means that the characteristic or attribute would be readily recognized by one of ordinary skill in the art, but does not require absolute precision or perfect agreement (e.g., within ±20% for quantifiable characteristics). The term "substantially," unless otherwise specified, means a high degree of approximation (e.g., within ±10% for quantifiable characteristics), but again, does not require absolute precision or perfect agreement. Terms such as identical, equal, uniform, constant, exactly, etc., are understood to not require absolute precision or perfect agreement, but rather within normal tolerances or measurement error applicable to the particular situation.

[0023] In a first aspect, the present disclosure provides an article, the article comprising: a) an adhesive layer having a first major surface and an opposite second major surface, the adhesive layer defining a first aperture having at least one edge, the first major surface of the adhesive layer not spontaneously wicking when contacted with an aqueous fluid; b) a film layer having a first major surface and a second major surface, the first major surface of the film layer bonded to the first major surface of the adhesive layer, the film layer defining a second aperture partially overlying the first aperture, the second major surface of the film layer being a microstructured surface comprising a plurality of capillary channels, each of the plurality of capillary channels being in fluid communication with the second aperture and extending toward a periphery of the film layer, a surface of each of the capillary channels exhibiting spontaneous wicking when contacted with an aqueous fluid; c) a cover layer disposed over the plurality of capillary channels in the film layer.

[0024] Articles according to at least certain embodiments of the present disclosure are capable of spontaneously and uniformly transporting liquid (e.g., water, sweat, or other aqueous solutions) from a first aperture to a second aperture, into the capillary channel, and along the channel from the second aperture toward the periphery of the film layer. This ability is often referred to as wicking. Two general factors affect the ability of a channel to spontaneously transport liquid are (i) the structure or topography of the surface (e.g., capillarity, cavity shape) and (ii) the properties of the surface (e.g., surface energy). To achieve a desired amount of fluid transport capacity, designers may adjust the structure or topography of the film layer and / or the surface energy of the capillary channel surface. To achieve wicking, the surface of the capillary channel must be "wettable" by the liquid to be transported. Optionally, the susceptibility of a solid surface to wetting by a liquid is characterized by the contact angle that the liquid makes with the solid surface after the liquid is deposited on a horizontally positioned surface and allowed to stabilize thereon. This contact angle is sometimes referred to as the "static equilibrium contact angle," or simply referred to herein as the "advancing contact angle." In some cases, a material is considered hydrophilic if it has an advancing contact angle of less than 90 degrees.

[0025] In general, articles of the present disclosure include an adhesive layer including fluid collection apertures fluidly coupled to a film layer including parallel capillary channels. The adhesive apertures provide fluid collection zones of known cross-sectional area. Secondary apertures in the film layer are oriented approximately perpendicular to the capillary channels and form feed channels that transport fluid to individual microcapillaries (i.e., capillary channels) in a time-dependent sequence. Articles according to at least certain embodiments of the present disclosure provide multilayer articles that may be useful, for example, for acquiring liquid samples. Suitable applications include, for example, wearable medical devices (e.g., sweat sensors).

[0026] Certain optical sweat sensors determine total sweat volume as a function of time. This can be achieved by directing sweat through continuous microfluidic channels within a device adhesively or mechanically attached to the skin. The channel volume is defined by its height, width, and length. During exercise or heat exposure, eccrine glands produce sweat at a known physiological rate. Sweat accumulation creates pressure within a hermetically sealed collection area within the device, forcing sweat through vias into the channel and then down the channel due to pressure-driven flow. Total sweat volume is determined by measuring the distance sweat travels down the channel length. Sweat visualization can be aided by the addition of an indicator deposited within the channel. To minimize device size, the channel configuration can be a serpentine or spiral path, with the inlet end of the channel fluidly coupled to the sweat collection area and the outlet end vented to the atmosphere. An alternative configuration for volume determination that does not require a hermetic seal uses an absorbent or wicking material, such as paper or a hydrophilic membrane, to transport sweat by capillary action. In such a configuration, the paper or membrane strip is in fluid communication with the sweat collection area. Similar to a microfluidic channel, the volume is determined by the distance that sweat propagates through the wicking material by capillary action.

[0027] Another form of optical sweat sensor determines the concentration of an analyte in sweat. This can be achieved as a single measurement or in a continuous manner by monitoring changes in concentration as a function of time. Determining analyte concentration as a function of time requires a fluidically isolated analysis region containing an analytical reagent, which increases the complexity of such devices. An alternative to shunting the liquid to an isolated compartment is immobilization of the detection reagent on a wicking membrane, allowing sweat to flow through the membrane to a waste reservoir to ensure continuous flow over time.

[0028] However, several challenges exist when utilizing pressure flow or capillary action in wearable sweat sensing devices. When a device operates at a constant sweat pressure, the flow rate is proportional to the cross-sectional area of ​​the fluid channel. Smaller diameter channels have lower flow rates than larger channels. Additionally, at a constant pressure, the flow rate decreases as a function of channel distance. One solution is to create larger channels with shorter lengths, but the liquid in the larger channels may be displaced to undesired locations by the acceleration and deceleration (e.g., G-forces) of the device caused by movement during use. For example, G-forces of 2 G to 15 G, such as 5 G to 10 G, may be applied to the article against the forearm of an exercising person.

[0029] For articles to be used while a person is moving such that the article is subjected to G-forces of 5 G or more, 6 G or more, or 7 G or more, the capillary channels are preferably configured to have a smaller cross-sectional area than articles subjected to lower G-forces. For example, a suitable cross-sectional area for each of the capillary channels to minimize fluid loss from the capillary channels due to G-forces is 0.025 square millimeters (mm 2 ) or more, 0.030mm 2 Over 0.035mm 2 Over 0.040mm 2 Over, 0.045 2 Over 0.050mm 2 Over 0.055mm 2 Over 0.060mm 2 Over 0.065mm 2 Over 0.070mm 2 Over 0.075mm 2 Over 0.080mm 2 More than 0.085mm 2 Over 0.090mm 2 or more, or 0.095 mm 2 Over 0.400mm 2 Below, 0.375mm 2 Below, 0.350mm 2 Below, 0.325mm 2 Below, 0.300mm 2 Below, 0.275mm2 Below, 0.250mm 2 Below, 0.200mm 2 Below, 0.175mm 2 Below, 0.150mm 2 Below, 0.125mm 2 Below, 0.150mm 2 Less than or equal to 0.100 mm 2 The length of the capillary channel may be fixed, and the cross-sectional area may be modified by changing one or more of the channel's height or width. To visualize the fluid within the capillary channel, there may be a preferred orientation for a given cross-sectional area to optimize the aspect ratio.

[0030] In contrast, for articles that are used when a person is generally seated or moving such that they are subjected to G-forces of less than 5 G, 4 G or less, 3 G or less, or 2 G or less, there tends to be more flexibility in the cross-sectional area of ​​each of the capillary channels, minimizing the risk of fluid loss from the capillary channels due to G-forces. For example, a preferred cross-sectional area of ​​each of the capillary channels is 0.025 mm 2 Over 0.030mm 2 Over 0.035mm 2 Over 0.040mm 2 Over 0.045mm 2 Over 0.050mm 2 Over 0.055mm 2 Over 0.060mm 2 Over 0.065mm 2 Over 0.070mm 2 Over 0.075mm 2 Over 0.080mm 2 More than 0.085mm 2 Over 0.090mm 2 Over 0.095mm 2 Over 0.500mm 2 Below, 0.450mm 2 Below, 0.450mm 2 Below, 0.425mm 2 Below, 0.400mm 2 Below, 0.375mm 2 Below, 0.350mm 2Below, 0.325mm 2 Below, 0.300mm 2 Below, 0.275mm 2 Below, 0.250mm 2 Below, 0.200mm 2 Below, 0.175mm 2 Below, 0.150mm 2 Below, 0.125mm 2 Below, 0.150mm 2 Less than or equal to 0.100 mm 2 It can be the following:

[0031] While the use of absorbents or wicking membranes can overcome some of the flow fluctuations in microchannel systems, if sweat rates change during use (e.g., during periods of rest), capillary action can continue to propagate liquid, leading to erroneously high estimates of sweat volume. These challenges become more pronounced in devices for detecting analytes in sweat, where the requirement to controllably shunt sweat to distinct zones on the device creates complex flow dynamics and ventilation requirements.

[0032] Articles according to at least certain embodiments of the present disclosure provide a compact device attachable to a subject's skin that provides consistent and uniform collection of sweat from the subject. Optionally, the article also delivers sweat to at least one analytical detection chamber. These advantages are achieved by providing a device that uses a combination of pressure-driven delivery of sweat to a series of parallel compartments that are filled by capillary action. The use of a short supply channel overcomes problems associated with flow rate. As the supply channel (e.g., a second aperture) fills with sweat, aliquots of predetermined volume enter the capillary channels sequentially. Because each capillary is open at the end, there is no need to create individual vent holes or lanes within the device during assembly. The total volume is determined by the number of capillary channels filled per unit time, as defined by their length, width, and height. For any article of the present disclosure, the capillary channels may contain the same indicator chemistry (e.g., a reagent for measuring changes in ion concentration as a function of time) or may contain different reagents for determining multiple target analytes. Such a format simplifies manufacturing using roll-based processes without requiring site-specific alignment of reagent deposition.

[0033] Exemplary articles according to at least certain embodiments of the present disclosure are shown in Figures 1A-1D. Figure 1A is a generalized, exploded, schematic view of an exemplary article, Figure 1B is a generalized, schematic view of an exemplary article according to Figure 1A, Figure 1C is a cross-sectional view of the article of Figure 1B, Figure 1D is a generalized, schematic view of a portion of a film layer 1200 of the exemplary article, and Figure 1E is a generalized, schematic, cross-sectional view of another exemplary article according to Figure 1A. Article 1000 comprises an adhesive layer 1100 having a first major surface 1102 and an opposing second major surface 1104, adhesive layer 1100 defining a first aperture 1110 having at least one edge 1112, which in this embodiment is a plurality of edges 1112. First major surface 1104 of adhesive layer 1100 does not spontaneously wick when contacted with aqueous fluids (e.g., is hydrophobic). In certain embodiments, at least one edge 1112 of the first aperture 1110 also does not spontaneously wick when contacted with aqueous fluids.

[0034] For any of the above-described articles, the first aperture is optionally 0.25 square centimeters (cm 2 ) or more, 0.50cm 2 More than 0.75cm 2 More than 1.00cm 2 Over 1.25cm 2 Over 1.50cm 2 Over 1.75cm 2 Over 2.00cm 2 Over 2.25cm 2 or more, or 2.50 cm 2 Over 5.00cm 2 Below, 4.75cm 2 Below, 4.50cm 2 Below, 4.25cm 2 Below, 4.00cm 2 Below, 3.75cm 2 Below, 3.50cm 2 Below, 3.25cm 2 Below, 3.00cm 2 or 2.75 cm 2 In other words, the first aperture has an area of ​​0.25 to 5.00 cm2 (inclusive). Advantageously, a small area aids in successful collection of fluid at low flow rates and / or low total fluid volumes. The shape of the first aperture is not particularly limited and optionally includes, for example, a circle, a square, a rectangle, a branched shape, or any combination of shapes.

[0035] Suitable materials for the adhesive layer include, for example, pressure-sensitive adhesives. The adhesive layer can be prepared by coating a film of adhesive containing an adhesive polymer. Preferably, the adhesive comprises an adhesive polymer and a crosslinker. As used herein, the term "adhesive polymer" refers to a polymer that exhibits adhesion at ambient temperatures (e.g., 20-25°C). The adhesive polymer may be, for example, an acrylic polymer, polyurethane, polyolefin, or polyester. In select embodiments, the adhesive layer comprises a double-sided adhesive film. Some suitable commercially available double-sided adhesive films are available from 3M Company (St. Paul, MN) under the trade names 3M Medical Silicone Tape 2477P, and 3M Medical Tapes 1509, 1510, 1513, 1522, 9874, and 9877.

[0036] The article 1000 further comprises a film layer 1200 having a first major surface 1202 and a second major surface 1204, the first major surface 1202 of the film layer 1200 being bonded to the first major surface 1102 of the adhesive layer 1100. The film layer 1200 defines a second aperture 1210 disposed partially overlapping the first aperture 1110. By "partially overlapping" it is meant that a portion of the area of ​​the second aperture overlaps some or all of the area of ​​the first aperture. The second major surface 1204 of the film layer 1200 is a microstructured surface 1220 comprising a plurality of capillary channels 1222, each of which is in fluid communication with the second aperture 1210 and extends toward a periphery 1230 of the film layer 1200. In this embodiment, the capillary channels 1222 each extend in a direction perpendicular to the longitudinal axis of the second aperture 1210. However, in alternative embodiments, one or more of the capillary channels may extend in one or more directions, for example, at at least one angle other than 90° from the longitudinal axis of the second aperture extending in a curved direction, or any combination thereof. The surface 1224 of each of the capillary channels 1222 exhibits spontaneous wicking when contacted with aqueous fluids (e.g., is hydrophilic). In some embodiments, the second aperture 1210 has multiple edges 1212 that each do not spontaneously wick when contacted with aqueous fluids (e.g., are hydrophobic).

[0037] For any of the articles described above, the second aperture 1210 desirably has a width of 200 micrometers or more, 300 micrometers or more, 400 micrometers or more, 500 micrometers or more, 600 micrometers or more, 700 micrometers or more, or 800 micrometers or more, and 1500 micrometers or less, 1400 micrometers or less, 1300 micrometers or less, 1200 micrometers or less, 1100 micrometers or less, 1000 micrometers or less, or 900 micrometers or less.

[0038] In many embodiments, the film layer is hermetically sealed to the adhesive layer, thereby minimizing leakage of the fluid sample between the adhesive layer and the film layer.

[0039] 1B and 1C , the article 1000 further includes a cover layer 1300 disposed over the plurality of capillary channels 1222 of the film layer 1200. In these embodiments, the cover layer 1300 is attached to the first major surface 1102 of the adhesive layer 1100 adjacent the periphery 1230 of the film layer 1200. A height difference H between the film layer 1200 and the adhesive layer 1100 defines a gap 1310 between the periphery 1230 of the film layer 1200 and the cover layer 1300. The cover layer 1300 defines at least one vent 1320 in fluid communication with the gap 1310. The vent 1320 allows gas (e.g., air) displaced from at least one of the second aperture 1210 or the capillary channels 1222 to exit the article 1000 during fluid collection and transport within the article 1000.

[0040] 1E embodiment, in contrast, article 1000e includes a cover layer 1300 disposed over a plurality of capillary channels 1222 of film layer 1200, e.g., attached to the tops 1271 of at least some of capillary channels 1222. Each of capillary channels 1222 includes an end 1227 in fluid communication with second aperture 1210 and an opposing end 1229 open to the atmosphere, allowing each capillary channel 1222 to be vented.

[0041] For any of the above-described articles, the cover layer preferably has an area large enough to form an airtight seal with the top of the capillary channel and to cover the entire second aperture in the film layer. The fluid feed channel is (collectively) defined by the first major surface of the adhesive layer, the edges of the second aperture, and the major surface of the cover layer. In some embodiments, one or more of the edges of the second aperture, the major surface of the cover layer, or any combination thereof, do not spontaneously wick when contacted with an aqueous solution. In advantageous embodiments, each of the surfaces forming the fluid feed channel does not spontaneously wick when contacted with an aqueous solution.

[0042] In many embodiments of article 1000, a first portion 1223 of the plurality of capillary channels 1222 extends from the second aperture 1210 to a first edge 1232 of the outer periphery 1230 of the film layer 1200, and a second portion 1225 of the plurality of capillary channels 1222 extends from the opposite second aperture 1210 to a second edge 1234 of the outer periphery 1230 of the film layer 1200.

[0043] Advantageously, article 1000 further includes at least one reagent configured to react with a (e.g., fluid) sample and provide a response selected from, for example, an electrochemical response, an optical response, a fluorescent response, a chemiluminescent response, a pH adjustment, or any combination thereof. Article 1000 may include a first reagent 1250 disposed within first capillary channel 1222a. Article 1000 may also include a second reagent 1260 disposed within second capillary channel 1222b. The first reagent and / or second reagent are configured to react with a sample containing glucose, electrolytes, drugs, metabolites (e.g., drug metabolites), or any combination thereof. For example, determining the concentration of ions in sweat during exercise or prolonged exposure to a hot environment can provide information regarding hydration status. In select embodiments, the first reagent and / or second reagent include an acid, base, buffer, or any combination thereof to cause a change in the pH of the sample. Some suitable reagents include, for example, but are not limited to, fluorescent or chromogenic indicators, electrochemical reagents, agglutination reagents, analyte-specific binding agents, amplification agents such as enzymes and catalysts, photochromic agents, dielectric compositions, enzyme-linked antibody probes, DNA probes, RNA probes, analyte-specific reporters such as fluorescent or phosphorescent beads, or any combination thereof.

[0044] 1A, article 1000 further comprises a sensor 1350. In any embodiment, sensor 1350 is configured to communicate with a wireless network 1360. Data from sensor 1350 may thus be transmitted via wireless network 1360 to a device (e.g., a computer, a mobile device, etc.) to provide a record of results after article 1000 is worn by a subject, such as at least one response from a reaction between a reagent and fluid collected from the subject.

[0045] Preferably, the capillary channels 1222 are substantially uniform and regular along each channel length L. In many embodiments, at least one of the capillary channels 1222 is comprised of a sidewall 1221 (e.g., two sidewalls) configured to define the capillary channel 1222, the sidewall 1221 extending continuously from one end 1227 of the channel 1222 to an opposite end 1229 of the channel 1222. Referring to FIG. 1D , a diagram of a portion of a film layer 1200 of an exemplary article is provided. In this diagram, several visible features of the film layer 1200 include several capillary channels 1222. The capillary channels are each defined by (e.g., two) sidewalls 1221 and a bottom wall 1226. In this embodiment, the bottom wall 1226 is formed with a plurality of smaller, secondary channels 1228.

[0046] 2A, a cross-sectional schematic diagram of a film 2200a is provided having a microstructured surface 2220 in which capillary channels 2222 are defined by sidewalls 2221 that converge at the bottom of each capillary channel 2222 (e.g., the channels are V-shaped). FIG. 2B is a cross-sectional schematic diagram of another film 2200b having a microstructured surface 2220 in which capillary channels 2222 are defined by sidewalls 2221 and a bottom wall 2226 between sidewalls 2221. In a preferred embodiment, the first and second sidewalls of the capillary channels each intersect the bottom wall at an angle less than 90 degrees, configured to aid in capillary movement of sample entering the channel. Additional suitable designs of capillary channels in microstructured surfaces useful in any article of the present disclosure are described in detail, for example, in U.S. Pat. No. 7,223,364 (Johnston et al.), as shown, for example, in FIGS. 1a-1h, 9, and 10a-10c.

[0047] For any of the above-described articles, the capillary channels (1222, 2222) each desirably have a height of 100 micrometers or more, 200 micrometers or more, 300 micrometers or more, 400 micrometers or more, 500 micrometers or more, 600 micrometers or more, or 700 micrometers or more, and 3000 micrometers or less, 2500 micrometers or less, 2000 micrometers or less, 1500 micrometers or less, 1200 micrometers or less, 1000 micrometers or less, 900 micrometers or less, or 800 micrometers or less. It has been found that capillary channels with a greater height tend to provide more visually striking optical results than capillary channels with a smaller height.

[0048] For any of the above-described articles, the capillary channels (1222, 2222) each desirably have a width W of 20 micrometers or more, 30 micrometers or more, 40 micrometers or more, 50 micrometers or more, 60 micrometers or more, 80 micrometers or more, 100 micrometers or more, 125 micrometers or more, 150 micrometers or more, 175 micrometers or more, 200 micrometers or more, 250 micrometers or more, 300 micrometers or more, 350 micrometers or more, 400 micrometers or more, 450 micrometers or more, or 500 micrometers or more, and 1500 micrometers or less, 1400 micrometers or less, 1300 micrometers or less, 1200 micrometers or less, 1100 micrometers or less, 1000 micrometers or less, 900 micrometers or less, 800 micrometers or less, 700 micrometers or less, or 600 micrometers or less. It has been found that capillary channels having smaller widths are less likely to experience irregular fluid movement within the channel (e.g., sloshing) than capillary channels having larger widths when the article is subjected to movement (e.g., movement of a subject that can apply measurable G-forces to the article) as described above. In select embodiments, when a larger height is employed, for example, the smaller width may be selected to provide a suitable total cross-sectional area (e.g., as described above) and / or volume (e.g., as described below) for each capillary channel, or vice versa.

[0049] With respect to any of the above-described articles, the capillary channels (1222, 2222) each desirably have a flow rate of at least 0.25 microliters / centimeter, at least 0.50 microliters / centimeter, at least 0.75 microliters / centimeter, at least 1.00 microliters / centimeter, at least 1.25 microliters / centimeter, at least 1.50 microliters / centimeter, at least 1.75 microliters / centimeter, at least 2.00 microliters / centimeter, at least 2.25 microliters / centimeter, at least 2.50 microliters / centimeter, at least 2.75 microliters / centimeter, at least 3.00 microliters / centimeter, at least 3.25 microliters / centimeter, at least 3.50 microliters / centimeter, at least 3.75 microliters / centimeter (of the length of the channel). The capillary channels may each have a volume of 0.25 microliters / cm or more, or 4.00 microliters / cm or more, and 10.00 microliters / cm or less, 9.50 microliters / cm or less, 9.00 microliters / cm or less, 8.50 microliters / cm or less, 8.00 microliters / cm or less, 7.50 microliters / cm or less, 7.00 microliters / cm or less, 6.50 microliters / cm or less, 6.00 microliters / cm or less, 5.75 microliters / cm or less, 5.50 microliters / cm or less, 5.25 microliters / cm or less, 5.00 microliters / cm or less, 4.75 microliters / cm or less, or 4.50 microliters / cm or less. Alternatively stated, the capillary channels may each have a volume of 0.25 microliters / cm to 10 microliters / cm. Advantageously, the small volume aids in the successful transport of fluids through the capillary channels at low flow rates and / or low total fluid volumes.

[0050] Similarly, the plurality of channels (1222, 2222) of any of the above-described articles optionally have a volume of at least 0.1 milliliters (mL), at least 0.2 mL, at least 0.3 mL, at least 0.4 mL, at least 0.5 mL, at least 0.6 mL, at least 0.7 mL, at least 0.8 mL, at least 0.9 mL, at least 1.0 mL, at least 1.1 mL, at least 1.2 mL, at least 1.3 mL, at least 1.4 mL, at least 1.5 mL, at least 1.6 mL, at least 1.7 mL, at least 1.8 mL , 1.9 mL or more, 2.0 mL or more, 2.1 mL or more, 2.2 mL or more, 2.3 mL or more, or 2.4 mL or more, and 5.0 mL or less, 4.8 mL or less, 4.6 mL or less, 4.4 mL or less, 4.2 mL or less, 4.0 mL or less, 3.8 mL or less, 3.6 mL or less, 3.4 mL or less, 3.2 mL or less, 3.0 mL or less, 2.9 mL or less, 2.8 mL or less, 2.7 mL or less, 2.6 mL or less, or 2.5 mL or less. Stated differently, the channels may have a total volume of between 0.1 mL and 5.0 mL. Advantageously, a small total channel volume aids in successful filling of multiple capillary channels with fluid at low flow rates and / or low total fluid volumes.

[0051] For any of the above-described articles, the total volume provided by the plurality of capillary channels may be within 75%, 80%, 85%, 90%, or even 95% of the total theoretical volume of the film layer defined by the perimeter, width, and height of the capillary features. Stated differently, the article advantageously has less than 25%, 20%, 15%, 10%, or even less than 5% of the volume of the film layer occupied by the wall volume of the capillary channels. This relative area aids in providing a uniform flow rate under a constant pressure while providing an article that is desirably small and free of dead space.

[0052] Referring to Figure 3, a generalized schematic diagram of another exemplary article 3000 is provided. Article 3000 comprises an adhesive layer 3100 having a film layer 3200 bonded thereto and a cover layer 3300 disposed on film layer 3200. A first aperture 3110 in adhesive layer 3100 is visible. A second aperture 3210 in film layer 3200 is also provided. In an alternative design to the illustrated embodiment, the second aperture may extend all the way to the edge of the film layer, allowing fluid to enter the capillary channel downward along the entire length of the film layer. A first portion 3223 of the capillary channel and a second portion 3225 of the capillary channel are shown. In use, once the fluid fills the first aperture 3110, it begins to migrate through the second aperture 3210 and, at least because the hydrophilic surface of the capillary channel is less resistant to the fluid than the hydrophobic surface of the adhesive layer 3100 below the second aperture 3210, a pressure P F transports an aliquot of fluid into the capillary channels of first portion 3223 and second portion 3225 in a direction towards the periphery of article 3000.

[0053] For any of the articles described above, suitable polymeric materials for the film layer include, but are not limited to, polyolefins (e.g., high-density polyethylene (HDPE), medium-density polyethylene (MDPE), or low-density polyethylene (LDPE)), polyesters, polyamides, poly(vinyl chloride), polyetheresters, polyimides, polyesteramides, polyacrylates, polyvinyl acetate, or hydrolyzed derivatives of polyvinyl acetate. In certain embodiments, polyolefins are preferred because of their excellent physical properties, ease of processing (e.g., replicating the surface of a tool), and typically low cost. Polyolefins are also generally strong, durable, and retain their shape well, making them easy to handle after the article is formed. In select embodiments, the film layer comprises polyester polyethylene terephthalate (PET). One suitable commercially available PET is a 5 mil (127 micrometer) thick PET sheet under the trade designation "MELINEX 454" by Tekra (New Berlin, WI). A suitable commercially available LDPE is available from The Dow Chemical Company (Midland, MI) under the trade designation "DOW 955I LDPE." Additionally, the film layer may include various additives, such as surface energy modifiers (e.g., surfactants and hydrophilic polymers), plasticizers, antioxidants, pigments, release agents, antistatic agents, and the like.

[0054] For any of the above-described articles, the cover layer is optionally bonded to the top of the capillary channel of the film layer. One suitable method for bonding the cover layer to the capillary channel uses thermal bonding (e.g., fusion bonding). Additionally, the sensor may also be thermally bonded to the capillary channel, the cover layer, or both. In embodiments using thermal bonding, the film layer may be formed of a different polymeric material from the cover layer, including, for example, but not limited to, low-density polyethylene, ethylene vinyl acetate, polyurethane, copolymers of polyester and polyolefin, copolymers of polyurethane and aromatic poly(meth)acrylate, copolymers of polycaprolactone and polyurethane, or combinations thereof. One suitable commercially available polyurethane is available under the trade name "PEARLBOND 1160L" from Lubrizol (Wickliffe, OH). A suitable commercially available ethylene vinyl acetate (EVA) is available under the trade name "DUPONT ELVAX 3180" from The Dow Chemical Company (Midland, MI).

[0055] In some embodiments where a cover layer is bonded to the top of the capillary channels in the film layer, the film layer optionally has a Vicat softening temperature (T ) of 100 degrees Celsius (°C) or less, 95°C or less, 90°C or less, 85°C or less, 80°C or less, 75°C or less, or 70°C or less, and 45°C or more, 50°C or more, 55°C or more, 60°C or more, or 65°C or more. g ). The Vicat softening temperature of the film layer is often at least 10% lower than the Vicat softening temperature of the cover layer, and is 15%, 20%, 25%, 30%, 35%, or at least 40% lower than the Vicat softening temperature of the cover layer. In certain embodiments, the cover layer has a Vicat softening temperature (T ) of 150 degrees Celsius (°C) or lower, 145°C or lower, 140°C or lower, 130°C or lower, 120°C or lower, 115°C or lower, or 110°C or lower, and 65°C or higher, 70°C or higher, 75°C or higher, 80°C or higher, or 85°C or higher. g Using a cover layer that has a higher Vicat softening temperature than the film layer aids in thermally bonding the two layers together while minimizing conformation of the cover layer to the shape of the capillary channels.

[0056] In some embodiments in which a cover layer is bonded to the top of the capillary channels of the film layer, the cover layer optionally includes an adhesive. For example, the cover layer may have an adhesive coated on the major surface that is attached to the top of the capillary channels (e.g., a patterned adhesive or a substantially complete coating of adhesive), or the cover layer may be a multi-layer structure including an adhesive layer and at least one layer of the polymeric materials described above.

[0057] The hydrophilicity of the capillary channel of any of the above-described articles can be achieved by one or more of material selection, additives included in the material, or surface treatment. In some embodiments, the capillary channel has a surface comprising a surfactant, a surface treatment, a hydrophilic polymer, or a combination thereof. Suitable surfactants include, but are not limited to, C8-C18 alkane sulfonate; C8-C18 secondary alkane sulfonate; alkyl benzene sulfonate; C8-C18 alkyl sulfate; alkyl ether sulfate; sodium laureth tetrasulfate; sodium laureth octasulfate; dioctyl sulfosuccinate, sodium salt, lauroyl lactylate; stearoyl lactylate; or any combination thereof. The one or more surfactants can be applied by conventional methods, such as by wiping a coating of the surfactant on the surface of the capillary channel and allowing the coating to dry. Suitable surface treatments include hydrophilic coatings comprising plasma-deposited silicon / oxygen materials and / or diamond-like glass (DLG) materials. Plasma deposition of silicon / oxygen materials and DLG materials is described, for example, in PCT Publication WO 2007 / 075665 (Somasiri et al.). Further, examples of suitable DLG materials are disclosed in U.S. Patent Nos. 6,696,157 (David et al.), 6,881,538 (Haddad et al.), and 8,664,323 (Iyer et al.). Suitable hydrophilic polymers include, but are not limited to, polyesters, polyamides, polyurethanes, poly(vinyl alcohols), poly(alkylene glycols), poly(alkylene oxides), poly(vinylpyrrolidones), rubber elastomers, or any combination thereof.

[0058] In some embodiments, the adhesive layer, film layer, cover layer, or any combination thereof is transparent to visible light (as defined above). Providing one or more transparent layers can be advantageous for certain applications where the sample reaction can be optically detected through at least a portion of the article (e.g., the cover layer).

[0059] 4A-4D, a generalized schematic diagram of the time course of an exemplary article 4000 during use is shown. Use is described in more detail in Example 2 below. Briefly, FIG. 4A is a diagram of the article 4000 before filling with fluid (e.g., at time 0 seconds). FIG. 4B is a diagram of the article of FIG. 4A 4 minutes and 55 seconds after the first aperture 4110 begins filling with a colored fluid at a rate of 6 microliters / minute. It is clear that the first aperture 4110 is filled with fluid, and that very few capillary channels in the first portion 4223 and second portion 4225 have been filled. FIG. 4C is a diagram of the article of FIG. 4A 30 minutes and 55 seconds after the first aperture begins filling with a colored fluid. It is clear that the pressure of the fluid entering the first aperture at a rate of 6 microliters / minute is sufficient to continue to sequentially fill more capillary channels in the first portion 4223 and second portion 4225. FIG. 4D is a view of the article of FIG. 4A 60 minutes and 55 seconds after filling with the colored fluid began, with more capillary channels in first portion 4223 and second portion 4225 sequentially filling with fluid.

[0060] For any of the articles described above, the cover layer advantageously further includes an opaque region and an observation window region. For example, referring to FIG. 5 , an article 5000 is shown having a cover layer 5300 with an opaque region 5330 and an observation window region 5340. The article 5000 of FIG. 5 further includes an indicator 5332 related to the volume of the sample, the chemical nature of the sample, or both. For example, the article 5000 provides an optical response 5290 (i.e., a dark line within the observation window region 5340) after a reaction of at least a minimum amount of glucose in the subject's sweat with a first reagent. The article 5000 also provides an optical response 5290 based on a reaction of a second reagent with a component of the subject's sweat to indicate that a sufficient volume of the subject's sweat has been collected. Providing at least one optical response may be advantageous for any of the articles described above. Unexpectedly, it was discovered that after the first capillary channel was filled, very little color was transferred from the first capillary channel to subsequent capillary channels, thereby enabling the successful use of multiple chemistries in different capillary channels.

[0061] Referring to FIG. 6A, an article 6000 is shown that advantageously further comprises a discontinuous region 6270 on the surface of at least one capillary channel 6222 that interrupts a surface that exhibits spontaneous wicking (e.g., is hydrophilic) when contacted with aqueous fluids, where the discontinuous region 6270 comprises a surface that does not spontaneously wick (e.g., is hydrophilic) when contacted with aqueous fluids. The article in the figure includes discontinuous regions 6270 at three different locations, each spanning multiple capillary channels 6222. The article allows colored fluid to transport through the first aperture 6110 into the capillary channel 6222, thereby showing how the discontinuous hydrophobic region stops fluid flow through the capillary channel 6222, even though the remainder of the capillary channel 6222 extends beyond the discontinuous region, which has a hydrophilic surface. In some cases, the force of the fluid flow is sufficient to push the discontinuous region 6270 farther than the discontinuous region. The inclusion of such discontinuous regions can reduce the volume that each capillary channel fills with fluid from a second aperture before the fluid from the second aperture begins to fill adjacent capillary channels. This can be advantageous when only small amounts of fluid are expected to be collected from a subject. Referring to FIG. 6B , an SEM image of a portion of a capillary channel 6222 of an exemplary article having discontinuous regions 6270 on its surface is provided. The image reveals the presence of discontinuous regions 6270 (e.g., hydrophobic) on the top and bottom walls 6226 of each of the sidewalls 6221 of the capillary channel 6222. The surfaces 6224 on either side of the discontinuous regions 6270 exhibit spontaneous wicking when contacted with aqueous fluid (e.g., hydrophilic). For example, the discontinuous regions can be formed using laser ablation or mechanical cutting.

[0062] For any of the above-described articles, a tie layer can be disposed between two adjacent layers (e.g., between a cover layer and a film layer). Some suitable tie layers are described in U.S. Pat. No. 10,098,980 (Karls et al.) and include thermoplastic compositions including copolymers of at least one olefin monomer and at least one polar monomer, and / or block copolymers including alkyl methacrylate and alkyl acrylate blocks. The tie layer can be applied in a pattern.

[0063] Example The objects and advantages of the present disclosure are further illustrated by the following examples, although the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this disclosure. Unless otherwise stated or apparent from the context, all parts, percentages, ratios, etc. in the examples and elsewhere in this specification are by weight. The Table of Materials (below) lists the materials used in the examples and their suppliers.

[0064] [Table 1]

[0065] Preparation of glucose indicator A solution containing 4-aminoantipyrine (1.5 mM) and 3-(N-ethyl-methylanilino)-2-hydroxypropanesulfonic acid sodium salt (1.5 mM) in PBS was prepared. A 1 mL aliquot of the solution was added to an Eppendorf tube, and glucose oxidase / peroxidase solution (100 microliters) was added with mixing.

[0066] Preparation of adhesive layer A rectangular section (6 cm long x 5 cm wide) of double-sided adhesive film was used as the adhesive layer (3M Double-Sided Tape 9425HT, obtained from 3M Corporation, St. Paul, MN). A laser cutter (Muse Laser Cutter, obtained from Full Spectrum Laser, Las Vegas, NV) was used to cut a 0.5 cm x 2 cm rectangular section from the adhesive layer to form a first aperture. The first aperture was positioned at one end of the adhesive layer, with one long edge of the first aperture positioned 0.5 cm from the edge of the adhesive layer and each of the two narrow edges of the first aperture positioned 1.5 cm from the edge of the adhesive layer.

[0067] Preparation of film layers An extrusion microreplication molding process described in U.S. Pat. No. 10,378,813 was used to prepare a polypropylene film (C700-35N, The Dow Chemical Company, Midland, MI) with a microstructured surface containing a plurality of parallel capillary channels. The capillary channels of the microstructured surface consisted of first walls having a height of approximately 600 micrometers, spaced approximately 700 micrometers apart. At the base of each channel are 10 second capillary channels formed by walls having a height of approximately 35 micrometers, a top width of approximately 25 micrometers, and spaced approximately 40 micrometers center-to-center. A hydrophilic silicon-containing layer was applied to the microstructured surface using a Plasma-Therm 3032 batch plasma reactor (obtained from Plasma-Therm LLC, St. Petersburg, FL). The tool was configured for reactive ion etching using a 26-inch (66.04 cm) low-power electrode and a central gas pump. The chamber was heated with a dry mechanical pump (Edwards The system was pumped with a roots-type blower (model EH1200 obtained from Edwards Engineering, Burgess Hill, UK) backed by a model iQDP80 obtained from Edwards Engineering. RF power was provided by a 3 kW, 13.56 MHz solid-state generator (RFPP model RF30S obtained from Advanced Energy Industries, Fort Collins, CO). The system had a nominal base pressure of 5 mTorr. Gas flow rates were controlled by MKS flow regulators (MKS The plasma was controlled by a plasma analyzer (obtained from Sigma-Aldrich Instruments, Andover, MA). The film sample was fixed onto the powered electrode of the plasma reactor. After pumping down to base pressure, the gases tetramethylsilane (TMS) and oxygen (O2) were introduced. The film was plasma treated in a two-step process as follows: Step 1: TMS flow rate of 150 sccm (standard cubic centimeters per minute), oxygen flow rate of 500 sccm, and deposition time of 30 seconds; Step 2: Oxygen at a flow rate of 500 sccm for 20 seconds. After completion of the plasma treatment, the chamber was vented to atmosphere, and the plasma-treated film was removed from the chamber.

[0068] A laser cutter (Muse Laser Cutter, obtained from Full Spectrum Laser, Las Vegas, NV) was used to create rectangular sections (5 cm long x 4 cm wide) of the plasma-treated film, with the capillary channels oriented parallel to the width (minor) dimension and extending to the edge of the section. A razor blade was used to cut a rectangular section of the film approximately 1 mm wide from the center of the microchannel film, starting approximately 7 mm from one edge and extending to the opposite edge of the film. The removed section provided a second aperture that formed a narrow feed channel oriented parallel to the length dimension and extending perpendicular to the capillary channels.

[0069] Example 1. Fluid Collection Article The fluid collection article shown in Figures 1A-1C was prepared using the adhesive and film layers prepared as described above. The non-microstructured surface of the film layer was adhesively attached to the adhesive layer. The layers were oriented so that the film layer was centered on the adhesive layer, with the second aperture in the adhesive layer partially overlapping (by approximately 2 mm) with the first aperture in the film layer. This construction resulted in a 1 cm border of exposed adhesive along the outer edge of the assembly. A 6 cm x 5 cm section of TEGADERM Transparent film #16004 (obtained from 3M Corporation) was used as the cover layer. The cover layer was positioned with the adhesive side facing the microstructured surface and was edge-aligned with the outer periphery of the assembly. The cover layer was secured by adhesive attachment to the top surface of the channel walls and the exposed surface of the adhesive layer. The construction formed a continuous air gap around the periphery, including the end of the capillary channel. A vent hole was created in the cover layer by puncturing it once with a 20-gauge syringe needle. The vent hole was located above the air gap on the side of the assembly distal from the first aperture.

[0070] Example 2. Delivery of liquid (water) to a fluid collection article A fluid delivery device was constructed containing a 1 / 16 inch (1.6 mm) channel drilled through a 3 / 16 inch (4.8 mm) thick sheet of polycarbonate. The channel opening on the bottom was fluidly connected to a 1 mL syringe. The completed fluid control article of Example 1 was attached to the top of the device using double-sided tape. The article was oriented with the adhesive layer facing the surface of the device and the first aperture resting on the first surface over the channel opening. The device was set up so that the article was placed in a flat, horizontal position. The syringe was filled with deionized water containing green food coloring. The syringe was placed in a syringe pump, and the liquid was delivered at a constant flow rate of 6 microliters / minute. The progress of the liquid through the device was monitored using a video camera. The liquid was observed to fill the first aperture first, followed by entry into the second aperture (the feed channel). As the liquid filled the second aperture (the feed channel), it entered the capillary channels continuously at the liquid front. The capillary channels filled completely and continuously without breaks or interruptions within the channels or between adjacent channels. The results obtained regarding the progression of the liquid through the device are shown in Table 1.

[0071] [Table 2]

[0072] Example 3. Liquid (artificial sweat) delivery to a fluid collection article (horizontal orientation of capillary channels) The same procedure as described in Example 2 was followed, except that artificial sweat solutions (artificial eccrine sweat #1700-0556 or artificial apocrine sweat #1700-0022, obtained from Pickering Laboratories, Inc.) were used as the liquid. Both artificial sweat solutions filled the capillary channels of the article in the same complete, continuous, and uninterrupted manner as described in Example 2. The results obtained regarding the progression of liquid through the device using artificial apocrine sweat are shown in Table 2.

[0073] [Table 3]

[0074] Example 4. Liquid (artificial sweat) delivery to a fluid collection article (vertical orientation of capillary channels) The same procedure was followed as described in Example 3, except that the device setup was modified to orient the article in a vertical position. The artificial sweat solution filled the capillary channels of the article in the same complete, continuous, and uninterrupted manner as described in Example 3.

[0075] Example 5. Color Indication of Glucose Using Fluid Collection Articles A 1 mL syringe equipped with a 25-gauge hypodermic needle was filled with the glucose indicator solution (described above). A portion of the glucose indicator solution was added to fill a single capillary channel in the film layer. A separate 1 mL syringe equipped with a 25-gauge hypodermic needle was filled with an aqueous solution of green food coloring. A portion of the green indicator solution was added to fill a single capillary channel located downstream (approximately 0.5 cm) from the channel filled with glucose indicator. This channel was prepared to act as a liquid flow indicator. The film was placed under a nitrogen stream to evaporate the solvent and form a dried indicator coating in the two channels. The film layer was then incorporated into the completed fluid collection article described in Example 1. A second cover layer was applied over the TEGADERM cover layer. The second cover layer was opaque white vinyl tape (Tape Product #471 obtained from 3M Company) with an observation window positioned over a portion of the capillary channel (including the indicator-coated channel). Following the procedure described in Example 2, a glucose solution (standard solution diluted to a glucose concentration of 14 milligrams / deciliter) was introduced into the article at a flow rate of 6 microliters / minute. The resulting images were analyzed using ImagePro Plus image processing software (Media Cybernetics, Rockville, MD). The color density of the indicator-coated channels was determined using the line profile tool. The color formation change was determined to be complete in approximately 30 minutes. Visual inspection of the glucose indicator-coated channels showed a color change from colorless to purple, indicating a positive response to glucose in the injected fluid. Visual inspection of the green dye-coated channels showed a color change from light green to dark green, indicating a positive response to liquid flow within the article.

[0076] Example 6. Effect of exercise on fluid retention Three-layer test articles for determining the effect of motion on liquid retention in capillary channels were prepared according to the procedure of Example 1, except that the adhesive layer did not have a first aperture and the film layer did not have a second aperture. The dimensions of the test articles were also varied. The overall capillary channel length was either 1 cm or 2 cm long. In some test articles, films were used with channels having a smaller first wall height (approximately 180 micrometers), a first wall spacing (approximately 180 micrometers), and only three secondary channels within the base of each channel. The microcapillary channels were then filled with water containing green food coloring. A 1 mL syringe with a 26-gauge needle was used to fill each channel with liquid. The channels were accessed by puncturing the cover sheet at the air gap section.

[0077] The prepared test article was attached to a small aluminum plate using double-sided tape with the cover sheet surface exposed for visualization. The plate was secured to the forearm of a human subject using a hook and loop attachment strap. The plate was attached to the forearm so that the long axis of the capillary channel was oriented parallel to gravity when the forearm was held in a position parallel to the floor. A data-logging, three-axis accelerometer (Model PCE-VDL 16 L, obtained from PCE Instruments, Jupiter, FL) was attached to a strap on the top of the forearm with the Z-axis detector oriented parallel to gravity. In some cases, the aluminum plate and accelerometer (in the same orientation as described above) were held in the subject's hand.

[0078] Subjects generated different exercise conditions by vigorously moving their arms in a back-and-forth motion while either walking, jogging, or sprinting. The maximum g-force (acceleration) was recorded for each condition. After exercise was stopped, the test articles were visually analyzed to determine whether any liquid had been released from the channels. The results are reported in Table 3.

[0079] [Table 4]

[0080] Example 7. Fluid Collection Article with Discontinuous Regions An article was prepared according to the procedure of Example 1, except that sections of the capillary channels in the film layer were laser cut with partial-depth cuts to create discontinuous areas within the channels prior to assembly of the article. The partial-depth cuts were made perpendicular to the channel direction across multiple adjacent channels. The cuts were made at three different distances (0.5 cm, 1.0 cm, and 1.5 cm) measured from the edge of the second aperture (feed channel). A liquid (water containing green food coloring) was injected into the article according to the procedure described in Example 2. The liquid was observed to move continuously through the capillary channels, but the liquid stopped in each channel at the location of the partial-depth cut (shown in FIG. 6A).

[0081] All of the above patents and patent applications are expressly incorporated herein by reference. The above-described embodiments are illustrative of the invention, and other constructions are possible. Accordingly, the present invention should not be deemed limited to the embodiments described in detail above and illustrated in the accompanying drawings, but rather should be limited only by the fair scope of the following claims, including equivalents. The following are exemplary embodiments. [Item 1] a) an adhesive layer having a first major surface and an opposite second major surface, the adhesive layer defining a first aperture having at least one edge, the first major surface of the adhesive layer not spontaneously wicking when contacted with an aqueous fluid; b) a film layer having a first major surface and a second major surface, the first major surface of the film layer bonded to the first major surface of the adhesive layer, the film layer defining a second aperture partially overlapping the first aperture, the second major surface of the film layer being a microstructured surface comprising a plurality of capillary channels, each of the plurality of capillary channels being in fluid communication with the second aperture and extending toward a periphery of the film layer, the surface of each of the capillary channels exhibiting spontaneous wicking when contacted with an aqueous fluid; c) a cover layer disposed over the plurality of capillary channels of the film layer; and An article comprising: [Item 2] 2. The article of claim 1, wherein the cover layer is attached to the first major surface of the adhesive layer adjacent the periphery of the film layer, a height difference between the film layer and the adhesive layer defining a gap between the periphery of the film layer and the cover layer, and the cover layer defines at least one vent in fluid communication with the gap. [Item 3] 3. The article of claim 1, wherein a first portion of the plurality of capillary channels extends from the second aperture to a first edge of the periphery of the film layer, and a second portion of the plurality of capillary channels extends from the second aperture to an opposite second edge of the periphery of the film layer. [Item 4] 4. The article of any one of items 1 to 3, further comprising a first reagent disposed in the first capillary channel. [Item 5] Item 5. The article of item 4, further comprising a second reagent disposed in the second capillary channel. [Item 6] 6. The article of claim 4 or 5, wherein the first reagent, the second reagent, or both are configured to react with a sample and provide a response selected from electrochemical, optical, fluorescent, chemiluminescent, pH adjustment, or a combination thereof. [Item 7] 7. The article of claim 6, wherein the first reagent, the second reagent, or both are configured to react with a sample containing glucose, an electrolyte, a drug, a metabolite, or a combination thereof. [Item 8] 8. The article of any one of items 1 to 7, wherein the at least one edge of the first aperture does not spontaneously wick when contacted with an aqueous fluid. [Item 9] 9. The article of any one of items 1 to 8, wherein the cover layer comprises an opaque region and an observation window region. [Item 10] 10. The article of claim 9, wherein the opaque region includes an indicator of the volume of the sample, an indicator of the chemistry of the sample, or both. [Item 11] 11. The article according to any one of items 1 to 10, wherein the cover layer further comprises a sensor. [Item 12] 12. The article of any one of items 1-11, wherein the capillary channels each have a height of 100 micrometers or more, 200 micrometers or more, 300 micrometers or more, 400 micrometers or more, 500 micrometers or more, 600 micrometers or more, or 700 micrometers or more, and 3000 micrometers or less, 2500 micrometers or less, 2000 micrometers or less, 1500 micrometers or less, 1200 micrometers or less, 1000 micrometers or less, 900 micrometers or less, or 800 micrometers or less. [Item 13] 13. The article of any one of items 1-12, wherein the capillary channels each have a width of 20 micrometers or more, 30 micrometers or more, 40 micrometers or more, 50 micrometers or more, 60 micrometers or more, 80 micrometers or more, 100 micrometers or more, 125 micrometers or more, 150 micrometers or more, 175 micrometers or more, 200 micrometers or more, 250 micrometers or more, 300 micrometers or more, 350 micrometers or more, 400 micrometers or more, 450 micrometers or more, or 500 micrometers or more, and 1500 micrometers or less, 1400 micrometers or less, 1300 micrometers or less, 1200 micrometers or less, 1100 micrometers or less, 1000 micrometers or less, 900 micrometers or less, 800 micrometers or less, 700 micrometers or less, or 600 micrometers or less. [Item 14] 14. The article of any one of items 1 to 13, wherein the capillary channels each have a volume of 0.25 microliters / centimeter to 10 microliters / centimeter. [Item 15] 15. The article of any one of items 1 to 14, wherein the plurality of capillary channels have a surface comprising a surfactant, a surface treatment, a hydrophilic polymer, or a combination thereof. [Item 16] 16. The article of any one of items 1 to 15, wherein the first aperture has an area in the range of 0.25 to 5.00 square centimeters. [Item 17] 17. The article of any one of items 1 to 16, wherein the plurality of capillary channels have a total volume of 0.1 milliliters to 5 milliliters. [Item 18] 18. The article of any one of items 1 to 17, wherein the film layer comprises a polyolefin, a polyester, a polyamide, a poly(vinyl chloride), a polyetherester, a polyimide, a polyesteramide, a polyacrylate, a polyvinyl acetate, or a hydrolyzed derivative of polyvinyl acetate. [Item 19] 19. The article of any one of the preceding claims, further comprising discontinuous regions on the surface of at least one capillary channel that interrupt the surface that exhibits spontaneous wicking when contacted with aqueous fluids, the discontinuous regions comprising a surface that does not spontaneously wick when contacted with aqueous fluids. [Item 20] 20. The article of any one of items 1-19, wherein the first major surface of the adhesive layer, the second aperture, and the major surface of the cover layer together define a fluid feed channel, and the fluid feed channel does not spontaneously wick when contacted with an aqueous solution.

Claims

1. a) an adhesive layer having a first major surface and an opposite second major surface, the adhesive layer defining a first aperture having at least one edge, the first major surface of the adhesive layer not spontaneously wicking when contacted with an aqueous fluid; b) a film layer having a first major surface and a second major surface, the first major surface of the film layer bonded to the first major surface of the adhesive layer, the film layer defining a second aperture partially overlapping the first aperture, the second major surface of the film layer being a microstructured surface comprising a plurality of capillary channels, each of the plurality of capillary channels being in fluid communication with the second aperture and extending toward a periphery of the film layer, the surface of each of the capillary channels exhibiting spontaneous wicking when contacted with an aqueous fluid; c) a cover layer disposed over the plurality of capillary channels of the film layer; and An article comprising:

2. 2. The article of claim 1, wherein the cover layer is attached to the first major surface of the adhesive layer adjacent the periphery of the film layer, a height difference between the film layer and the adhesive layer defining a gap between the periphery of the film layer and the cover layer, and the cover layer defines at least one vent in fluid communication with the gap.

3. 3. The article of claim 1 or claim 2, wherein a first portion of the plurality of capillary channels extends from the second aperture to a first edge of the periphery of the film layer, and a second portion of the plurality of capillary channels extends from the second aperture to a second edge of the periphery of the film layer opposite the second aperture.

4. The article of any one of claims 1 to 3, further comprising a first reagent disposed in the first capillary channel.

5. further comprising a second reagent disposed in the second capillary channel; 5. The article of claim 4, wherein the first reagent, the second reagent, or both are configured to react with a sample and provide a response selected from electrochemical, optical, fluorescent, chemiluminescent, pH adjustment, or a combination thereof.

6. 6. The article of claim 5, wherein the first reagent, the second reagent, or both are configured to react with a sample containing glucose, an electrolyte, a drug, a metabolite, or a combination thereof.

7. The article of any one of claims 1 to 6, wherein the cover layer comprises an opaque region and an observation window region.

8. The article of any one of claims 1 to 7, wherein the cover layer further comprises a sensor.

9. The article of any one of claims 1 to 8, wherein the capillary channels each have a volume of between 0.25 microliters / centimeter and 10 microliters / centimeter.

10. The article of any one of claims 1 to 9, wherein the plurality of capillary channels have a surface comprising a surfactant, a surface treatment, a hydrophilic polymer, or a combination thereof.

11. The article of any one of claims 1 to 10, wherein the first aperture has an area in the range of 0.25 to 5.00 square centimeters.

12. 12. The article of any one of claims 1 to 11, further comprising discontinuous regions on the surface of at least one capillary channel that interrupt the surface that exhibits spontaneous wicking when contacted with aqueous fluids, the discontinuous regions comprising a surface that does not spontaneously wick when contacted with aqueous fluids.

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