WO2022093214A1

WO2022093214A1 - Fluid degradable barrier valves for self-wicking substrates

Info

Publication number: WO2022093214A1
Application number: PCT/US2020/057734
Authority: WO
Inventors: Benjamin Abelovski; Beverly CHOU; Anita Rogacs
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2020-10-28
Filing date: 2020-10-28
Publication date: 2022-05-05

Abstract

The present disclosure relates to forming a fluid degradable barrier valve with materials including a self-wicking porous substrate and a barrier valve formulation. The barrier valve formulation can include from about 1 wt% to about 20 wt% of a hydrophobic material dispersed or dissolved in an aqueous liquid vehicle including water and from about 5 wt% to about 30 wt% of an organic co-solvent having a negative partition coefficient.

Description

FLUID DEGRADABLE BARRIER VALVES FOR SELF-WICKING SUBSTRATES

BACKGROUND

[0001] Self-wicking devices are intended to detect the presence of a target analyte(s) in a sample fluid. Self-wicking devices can be simple to use and can be used without specialized training. Accordingly, self-wicking devices are widely used for medical diagnostic testing, environmental sample testing, and in laboratories, to name a few applications.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002] FIG. 1 schematically illustrates an example kit for forming a fluid degradable barrier valve in accordance with the present disclosure;

[0003] FIG. 2 schematically illustrates an example branched self-wicking porous substrate that can be used in the kit of FIG. 1 in accordance with the present disclosure;

[0004] FIG. 3 graphically illustrates a method of forming a fluid degradable barrier valve in accordance with the present disclosure; and

[0005] FIG. 4 schematically illustrates a system for manufacturing a fluid degradable barrier valve of a self-wicking porous substrate.

DETAILED DESCRIPTION

[0006] Self-wicking substrates can be incorporated into devices that can permit the detection of a target analyte in a sample fluid. The sample fluid sequentially runs along the self-wicking porous substrate via capillary flow. When a target analyte is present in the sample fluid, the target analyte will interact with a compound having a functional group that is capable of binding to the target analyte. A testing region on the porous substrate can detect a complex of the target analyte and the compound and a control region on the porous substrate can detect the compound. When a complex of the target analyte and the compound is detected in the testing region an optical indicator will appear or will not appear, depending on the device type. When the compound is detected in the control region an optical indicator will appear, such as a line. Self-wicking porous substrates can incorporate barriers and/or barrier valves to control fluid flow there through. Formation of these barriers may be limited due to ability to control the placement of the barrier and/or barrier valves during formation.

[0007] In accordance with an example of the present disclosure, a kit for forming a fluid degradable barrier valve is presented. The kit can include a self-wicking porous substrate and a barrier valve formulation. The barrier valve formulation can include from about 1 wt% to about 20 wt% of a hydrophobic material dispersed or dissolved in an aqueous liquid vehicle including water and from about 5 wt% to about 30 wt% of an organic co-solvent having a negative partition coefficient. In an example, the self-wicking porous substrate can include nitrocellulose, cellulose, acetate cellulose, fiberglass, porous silica, polyester, surface modified polyester, hydrogel, nylon, polytetrafluorethylene, silica, or a combination thereof. In another example, the pores of the self-wicking porous substrate have an average pore size ranging from about 500 nm to about 50 pm. In yet another example, the hydrophobic material can include a paraffin wax, a polyethylene wax, a fluorothermoplastic, a latex, or a combination thereof. In a further example, the hydrophobic material can be dispersed in the aqueous liquid vehicle and can have a D50 particle size in a range of from about 80 nm to 300 nm. In one example, the organic co-solvent can be selected from glycerol, 2-pyroolidone, acetamide, methanol, formic acid, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, polypropylene glycol, formic acid, acetic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, mixtures or combinations thereof, in another example, the organic co-solvent can be hydrophobic. In yet another example, the negative partition coefficient of the organic co-solvent can range from about -2.0 to about -0.5. In a further example, the kit can include a second barrier valve formulation. The second barrier valve formulation can include from about 1 wt% to about 20 wt% of a second hydrophobic material dispersed or dissolved in a second aqueous liquid vehicle including water and from about 5 wt% to about 30 wt% second organic co-solvent having a second negative partition coefficient that can be different than the negative partition coefficient of the organic co-solvent.

[0008] Also presented herein is a method of forming a fluid degradable barrier valve (“method”). The method can include selectively dispensing a barrier valve formulation from a fluid applicator to penetrate a self-wicking porous substrate and form a fluid degradable barrier at the self-wicking porous substrate. The barrier valve formulation can include from about 1 wt% to about 20 wt% of a hydrophobic material dispersed or dissolved in an aqueous liquid vehicle including water and from about 5 wt% to about 30 wt% of an organic co-solvent having a negative partition coefficient. In an example, the fluid applicator can include a fluidjet printhead and the barrier valve formulation can have a viscosity suitable to dispense from the fluidjet printhead. In another example, the method can further include selectively dispensing a second barrier valve formulation onto the porous substrate at a second location of the self-wicking porous substrate. The second barrier valve formulation can include from about 1 wt% to about 20 wt% of a second hydrophobic material dispersed or dissolved in a second aqueous liquid vehicle including water and from about 5 wt% to about 30 wt% of a second organic co-solvent having a second negative partition coefficient. The second negative partition coefficient can be different than the negative partition coefficient of the organic co-solvent. In yet another example, the method can further include curing the barrier valve formulation penetrated in the self-wicking porous substrate by heating the self-wicking porous substrate to a temperature ranging from about 50 °C to about 150 °C for a period of time ranging from about 30 seconds to about 2 minutes. [0009] Further presented herein is a system for manufacturing a fluid degradable barrier valve on a self-wicking porous substrate. The system can include a fluidjet ejector, a barrier valve formulation, and a hardware controller. The fluidjet ejector can be configured to eject a barrier valve formulation from a reservoir when loaded therein. The barrier valve formulation can be loaded in or loadable within the reservoir. The barrier valve formulation can include from about 1 wt% to about 20 wt% of a hydrophobic material dispersed or dissolved in an aqueous liquid vehicle including water and from about 5 wt% to about 30 wt% organic co-solvent having a negative partition coefficient. The hardware controller can be operable to generate a command to control the fluidjet ejector to apply the barrier valve formulation dropwise onto a self-wicking porous substrate at a user designated location or multiple locations. The fluidjet ejector can be controllable by the hardware controller to eject as little as a single drop of the barrier valve formulation at the user designed location or multiple locations. In one example, the system can further include a second fluidjet ejector and a second barrier valve formulation. The second fluidjet ejector can be operable to eject a second barrier valve formulation from a second reservoir when loaded therein. The second barrier valve formulation can be loaded in or loadable within the second fluidjet ejector. The second barrier valve formulation can include from about 1 wt% to about 20 wt% of a second hydrophobic material dispersed or dissolved in a second aqueous liquid vehicle including water and from about 5 wt% to about 30 wt% of a second organic co-solvent having a second negative partition coefficient that is different than the negative partition coefficient of the organic co-solvent.

[0010] When discussing the kit for forming a fluid degradable barrier valve, the method of forming the fluid degradable barrier valve, and system for manufacturing a fluid degradable barrier valve on a self-wicking porous substrate herein, such discussions can be considered applicable to one another whether or not they are explicitly discussed in the context of that example. Thus, for example, when discussing an organic co-solvent with respect to the kit for forming a fluid degradable barrier valve, such disclosure is also relevant to and directly supported in the context of the method of forming the fluid degradable barrier valve, the system for manufacturing a fluid degradable barrier valve on a self-wicking porous substrate, and vice versa.

[0011] Terms used herein will be interpreted as the ordinary meaning in the relevant technical field unless specified otherwise. In some instances, there are terms defined more specifically throughout or included at the end of the present disclosure, and thus, these terms are supplemented as having a meaning described herein.

Kits for Forming Fluid Degradable Barrier Valves

[0012] A kit 100 for forming a fluid degradable barrier valve, as illustrated in FIG. 1 , can include a self-wicking porous substrate 1 10, and a barrier valve formulation 200. The barrier valve formulation can include from about 1 wt% to about 20 wt% of a hydrophobic material 210 dispersed or dissolved in an aqueous liquid vehicle 220 including water and from about 5 wt% to about 30 wt% organic co-solvent 225 having a negative partition coefficient.

[0013] The self-wicking porous substrate may include a fibrous substrate that can allow a sample fluid to flow there through via capillary action. In some examples, the self-wicking porous substrate can include nitrocellulose, cellulose, acetate cellulose, fiberglass, porous silica, polyester, surface modified polyester, hydrogel, or a combination thereof. In one example, the self-wicking porous substrate can include a nitrocellulose pad, a cellulose pad, or a fiberglass pad. In another example, the self-wicking porous substrate can include a nitrocellulose pad. Pores of the self-wicking porous substrate can have an average pore size ranging from about 500 nm to about 50 pm, from about 1 pm to about 10 pm, from about 5 pm to about 25 pm, from about 500 nm to about 5 pm, from about 10 pm to about 50 pm, or from about 2 pm to about 8 pm. A thickness of the self-wicking porous substrate can range from about 0.1 mm to about 1 mm, from 0.5 mm to about 1 mm, or from about 0.2 mm to about 0.8 mm. A length of the self-wicking porous substrate can range from about 1 mm to about 10 mm, from about 5 mm to about 10 mm, from about 1 mm to about 5 mm, or from about 2 mm to about 8 mm. A width of the self-wicking porous substrate can range from about 1 mm to about 20 mm, from about 5 mm to about 15 mm, or from about 8 mm to about 16 mm.

[0014] The self-wicking porous substrate can have a linear configuration, along which a fluid can flow. In some examples, the self-wicking porous substrate can include a linear pathway or can include multiple branched pathways and a linear pathway. For example, a self-wicking porous substrate 100, may include multiple branched pathways that combine to a single linear pathway. As shown in FIG. 2, the self-wicking porous substrate 110 may include three branched pathways (112a, 112b, and 112c) that combine to a single linear pathway 114. A quantity of the branched pathways can vary by application and can include 2, 3, 4, 5, 6, 7, 8, 9, or 10 branched pathways. The branched pathways can allow for multiple sample fluids to flow along the self-wicking porous substrate, wash fluids to flow along the self-wicking porous substrate, and/or reagent fluids to flow along the self-wicking porous substrate.

[0015] The self-wicking porous substrate can include multiple regions that can be designed to interact with an analyte in a sample fluid. In some examples, the self-wicking porous substrate can be part of a lateral flow immunoassay device and can include a complexing region and a detecting region. The complexing region in further detail can be a hydrophilic region and can have a pH ranging from about 6.5 to about 7.5, about 7 to about 7.5, or about 6.5 to about 7. In yet other examples, the complexing region can have a pH that can range from about 4 to about 10, about 4 to about 8, about 4 to about 6, or about 8 to about 10. The complexing region can be impregnated with a compound having a functional group that can bind with an analyte in a sample fluid to form an analyte complex. The complexing region can release the compound having the functional group to bind with the analyte in the sample upon application and movement of a sample fluid there through. The compound having a functional group to bind with an analyte in a sample may vary based on the analyte and the purpose of the lateral flow immunoassay device. In some examples, the compound having the functional group to bind with the analyte in the sample fluid can include a colloidal gold, a colored latex particle, a fluorescent latex particle, a paramagnetic latex particle, a cellulose nanobead, a florescent tag, or a combination thereof. The compound having the functional group to bind with the analyte can be a detection moiety that can be detected in a control strip of the detecting region; thereby indicating that a sample fluid has passed through the self-wicking porous substrate.

[0016] The detecting region can be configured to receive analyte from the complexing region. The detecting region can include a test strip and a control strip. The detecting region may be a sandwich format detecting region or a competitive format detecting region. A sandwich format detecting region can generate a positive result by displaying an optical indicator, such as a colored line. A competitive format detecting region can generate a positive result by displaying the absence of an optical indicator.

[0017] The barrier valve formulation in further detail, can include from about 1 wt% to about 20 wt% of a hydrophobic material dispersed or dissolved in an aqueous liquid vehicle including water and from about 5 wt% to about 30 wt% organic co-solvent having a negative partition coefficient. The dispersed or dissolved hydrophobic material can include a paraffin wax, a polyethylene wax, a fluorothermoplastic, a latex, or a combination thereof.

[0018] In some examples, the hydrophobic material can include a wax. The wax may include a paraffin wax, a polyethylene wax, a fluorothermoplastic, and combinations thereof. In some examples, the wax can be a wax emulsion. Wax emulsions are commercially available from Keim-Additec (Germany), The Lubrizol Corporation (USA), Michelman, Inc. (Japan), and BYK Chemie (Germany). Specific examples of wax emulsions can include, Lubrizol: LIQUILUBE™ 488 (melting point (mp) 85°C), LIQUILUBE™ 443 (mp 80°C), Michelman: ME48040 (mp 85°C), ME98040M1 (mp 98°C), ML160 (mp 85°C); Keim-Additec: ULTRALUBE® E-7093 (mp 84°C), ULTRALUBE® 7095/1 (mp 80°C), Byk: AQUACER® 2650 (mp 85°C), AQUACER® 533 (mp 95°C), AQUASLIP™ 942 (mp 83°C).

[0019] In some examples, the wax can be selected from a paraffin wax or modified paraffin wax with a relatively low melting point (e.g., a melting point below 100 °C). Specific examples of a paraffin wax or modified paraffin wax with a relatively low melting point include BYK Aquacer A494 with a melting point of about 60 °C, BYK Aquacer A497 with a melting point of about 60 °C, BYK Aquacer 8330 with a melting point of about 60 °C, BYK Aquacer 8333 with a melting point of about 60 °C, and BYK Aquacer 8335 with a melting point of about 58 °C (all available from BYK Chemie, Germany). In some examples, the relatively low melting point of the wax can allow the wax to enter the self-wicking porous substrate and cure without a heating step. In yet other examples, the wax can be selected from a paraffin wax or modified paraffin wax with a relatively high melting point (e.g., a melting point at or above 100 °C. An example can include BYK Aquacer 537 (available from BYK Chemie, Germany).

[0020] In yet other examples, the hydrophobic material can include a latex. The latex particles can be a polymer that can have different morphologies. In one example, the latex particles can include two different copolymer compositions, which may be fully separated core-shell polymers, partially occluded mixtures, or intimately comingled as a polymer solution. In another example, the latex particles can be individual spherical particles containing polymer compositions of hydrophilic (hard) component(s) and/or hydrophobic (soft) component(s) that can be interdispersed. In one example, the interdispersion can be according to IPN (interpenetrating networks). In yet another example, the latex particles can be composed of a hydrophobic core surrounded by a continuous or discontinuous hydrophilic shell. For example, the particle morphology can resemble a raspberry, in which a hydrophobic core can be surrounded by several smaller hydrophilic particles that can be attached to the core. In yet another example, the latex particles can include 2, 3, or 4 or more relatively large polymer particles that can be attached to one another or can surround a smaller polymer core. In a further example, the latex particles can have a single phase morphology that can be partially occluded, can be multiple-lobed, or can include any combination of any of the morphologies disclosed herein. [0021] In some examples, the latex particles can be heteropolymers or copolymers. As used herein, a heteropolymer can include a hydrophobic component and a hydrophilic component. A heteropolymer can include a hydrophobic component that can include from about 65% to about 99.9% (by weight of the heteropolymer), and a hydrophilic component that can include from about 0.1 % to about 35% (by weight of the heteropolymer). In one example, the hydrophobic component can have a lower glass transition temperature than the hydrophilic component.

[0022] In some examples, the latex particles can be composed of a polymerization or co-polymerization of acrylic monomers, styrene monomers, or a combination thereof. Example monomers can include, C1-C20 linear or branched alkyl (meth)acrylate, alicyclic (meth)acrylate, alkyl acrylate, styrene, methyl styrene, polyol (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylic acid, or a combination thereof. In one specific class of examples, the latex particles can be a styrene (meth)acrylate copolymer. The term “(meth)acrylate” or “(meth)acrylic acid” or the like refers to monomers, copolymerized monomers, etc., that can either be acrylate or methacrylate (or a combination of both), or acrylic acid or methacrylic acid (or a combination of both). In some examples, the terms “(meth)acrylate” and “(meth)acrylic acid” can be used interchangeably, as acrylates and methacrylates are salts and esters of acrylic acid and methacrylic acid, respectively. Furthermore, mention of one compound over another can be a function of pH. Thus, a monomer or a moiety of a polymer described as (meth)acrylic acid or as (meth)acrylate should not be read so rigidly as to not consider relative pH levels, ester chemistry, and other general organic chemistry concepts. In still another example, the latex particles can include a copolymer with copolymerized methyl methacrylate being present at about 50 wt% or greater, or copolymerized styrene being present at about 50 wt% or greater. Both can be present, with one or the other at about 50 wt% or greater in a more specific example.

[0023] In other examples, the latex particles can include polymerized monomers of vinyl, vinyl chloride, vinylidene chloride, vinyl ester, acrylate, methacrylate, styrene, ethylene, maleate esters, fumarate esters, itaconate esters, a-methyl styrene, p-methyl styrene, methyl methacrylate, hexyl acrylate, hexyl methacrylate, butyl acrylate, butyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, octadecyl acrylate, octadecyl methacrylate, stearyl methacrylate, vlnylbenzyl chloride, Isobornyl acrylate, tetrahydrofurfuryl acrylate, 2-phenoxyethyl methacrylate, benzyl methacrylate, benzyl acrylate, ethoxylated nonyl phenol methacrylate, isobornyl methacrylate, cyclohexyl methacrylate, trimethyl cyclohexyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, lauryl methacrylate, trydecyl methacrylate, alkoxylated tetrahydrofurfuryl acrylate, isodecyl acrylate, isobornylmethacrylate, isobornyl acrylate, dimethyl maleate, dioctyl maleate, acetoacetoxyethyl methacrylate, diacetone acrylamide, N-vinyl imidazole, N-vinylcarbazole, N-Vinyl-caprolactam, combinations thereof, derivatives thereof, or mixtures thereof. These monomers can include low glass transition temperature (Tg) monomers that can be used to form the hydrophobic component of a heteropolymer.

[0024] In other examples, a composition of the latex particles can include acidic monomers. In some examples, the acidic monomer content can range from about 0.1 wt% to about 15 wt%, from about 0.5 wt% to about 12 wt%, or from about 1 wt% to about 10 wt% of the latex particles with the remainder of the latex particles being composed of non-acidic monomers. Example acidic monomers can include acrylic acid, methacrylic acid, ethacrylic acid, dimethylacrylic acid, maleic anhydride, maleic acid, vinylsulfonate, cyanoacrylic acid, vinylacetic acid, allylacetic acid, ethylidineacetic acid, propylidineacetic acid, crotonoic acid, fumaric acid, itaconic acid, sorbic acid, angelic acid, cinnamic acid, styrylacrylic acid, citraconic acid, glutaconic acid, aconitic acid, phenylacrylic acid, acryloxypropionic acid, aconitic acid, phenylacrylic acid, acryloxypropionic acid, vinylbenzoic acid, N-vinylsuccinamidic acid, mesaconic acid, methacroylalanine, acryloylhydroxyglycine, sulfoethyl methacrylic acid, sulfopropyl acrylic acid, styrene sulfonic acid, sulfoethylacrylic acid, 2-methacryloyloxymethane- 1 -sulfonic acid, 3-methacryoyloxypropane-1 -sulfonic acid, 3-(vmyloxy)propane-1 -sulfonic acid, ethylenesulfonic acid, vinyl sulfuric acid,

4-vinylphenyl sulfuric acid, ethylene phosphonic acid, vinyl phosphoric acid, vinyl benzoic acid, 2-acrylamido-2-methyl-1 -propanesulfonic acid, combinations thereof, derivatives thereof, or mixtures thereof. These acidic monomers are higher Tg hydrophilic monomers, than the low Tg monomers above, and can be used to form the hydrophilic component of a heteropolymer. Other examples of high Tg hydrophilic monomers can include acrylamide, methacrylamide, monohydroxylated monomers, monoethoxylated monomers, polyhydroxylated monomers, or polyethoxylated monomers.

[0025] In an example, the selected monomer(s) can be polymerized to form a polymer, heteropolymer, or copolymer with a co-polymerizable dispersing agent. The co-polymerizable dispersing agent can be a polyoxyethylene compound, such as a HITENOL® compound (Montello Inc.) e.g., polyoxyethylene alkylphenyl ether ammonium sulfate, sodium polyoxyethylene alkylether sulfuric ester, polyoxyethylene styrenated phenyl ether ammonium sulfate, or mixtures thereof. Any suitable polymerization process can be used. In some examples, an aqueous dispersion of latex particles can be produced by emulsion polymerization or co-polymerization of any of the above monomers.

[0026] In one example, the latex particles can be prepared by polymerizing high Tg hydrophilic monomers to form the high Tg hydrophilic component and attaching the high Tg hydrophilic component onto the surface of the low Tg hydrophobic component. In another example, the latex particles can be prepared by polymerizing the low Tg hydrophobic monomers and the high Tg hydrophilic monomers at a ratio of the low Tg hydrophobic monomers to the high Tg hydrophilic monomers that can range from 5:95 to 30:70. In this example, the low Tg hydrophobic monomers can dissolve in the high Tg hydrophilic monomers. In yet another example, the latex particles can be prepared by polymerizing the low Tg hydrophobic monomers, then adding the high Tg hydrophilic monomers. In this example, the polymerization process can cause a higher concentration of the high Tg hydrophilic monomers to polymerize at or near the surface of the low Tg hydrophobic component. In still another example, the latex particles can be prepared by copolymenzing the low Tg hydrophobic monomers and the high Tg hydrophilic monomers, then adding additional high Tg hydrophilic monomers. In this example, the copolymerization process can cause a higher concentration of the high Tg hydrophilic monomers to copolymerize at or near the surface of the low Tg hydrophobic component.

[0027] The hydrophobic material may be particles of the hydrophobic material dispersed in the aqueous liquid vehicle. The particles can have a D50 particle size that can range from about 80 nm to about 300 nm. In yet other examples, the particles can have a D50 particle size that can range from about 100 nm to about 300 nm, about 80 nm to about 160 nm, about 200 nm to about 300 nm, about 150 nm to about 300 nm, or from about 90 nm to about 230 nm. As used herein, “D50” particle size refers to the particle size at which about half of the particles are larger than the D50 particle size and about half of the other particles are smaller than the D50 particle size (by weight based on the particle content). Particle size can be based on volume of the particle size normalized to a spherical shape for diameter measurement, for example. Particle size can be collected using a Malvern ZETASIZER™ from Malvern Panalytical (United Kingdom), for example.

[0028] The hydrophobic material may be dispersed or dissolved in the barrier valve formulation in an amount that can range from about 1 wt% to about 20 wt% based on the total weight of the barrier valve formulation. In some examples, the barrier valve formulation can include the hydrophobic material in an amount that can range from about 1 wt% to about 10 wt%, about 10 wt% to about 20 wt%, about 5 wt% to about 15 wt%, about 2 wt% to about 8 wt%, or about 12 wt% to about 18 wt%.

[0029] The hydrophobic material can be dispersed or dissolved in an aqueous liquid vehicle. In one example, the water can include water as a major solvent, e.g., the solvent present at the highest concentration when compared to other co-solvents. The aqueous liquid vehicle can be present in the aqueous liquid vehicle at from about 45 wt% to about 95 wt%, from about 60 wt% to about 94 wt% water, from about 70 wt% to about 90 wt%, from about 50 wt% to about 90 wt%, or from about 50 wt% to about 75 wt%, based on a total weight of the aqueous liquid vehicle.

[0030] Apart from water, the aqueous liquid vehicle may further include an organic co-solvent. In some examples, the organic co-solvent can be selected from glycerol, 2-pyroolidone, acetamide, methanol, formic acid, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, polypropylene glycol, formic add, acetic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, mixtures or combinations thereof. In yet other examples, the organic co-solvent can be selected from glycerol, 2-pyroolidone, methanol, formic acid, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, polypropylene glycol, mixtures or combinations thereof. The organic co-solvent may be a hydrophobic co-solvent, in some examples.

[0031] The organic co-solvent can have a negative partition coefficient. As used herein a “partition coefficient” refers to the ratio of concentrations of a chemical between two immiscible solvents, at equilibrium. One of the immiscible solvents is usually water, and the other is usually a hydrophobic solvent, such as 1 -octanol. If the chemical to which the partition coefficient pertains is also a solvent, then its partition coefficient may reflect its hydrophobicity and membrane permeability. In some examples, the negative partition coefficient of the organic co-solvent can range from about -2.0 to about -0.5, from about -1 .5 to about -0.5, from about -2.0 to about -1 .0, orfrom about -1 to about -0.5. The more positive the partition coefficient of the organic co-solvent, the longer it will take for a barrier valve formed in a self-wicking porous substrate to degrade when contacted by an aqueous fluid flowing there through.

[0032]The aqueous liquid may further include additional components such as a surfactant, a colorant, and/or a pH adjustor. The surfactant can include a non-ionic surfactant, a cationic surfactant, and/or an anionic surfactant. Example non-ionic surfactants can include self-emulsifiable, nonionic wetting agents based on acetylenic diol chemistry (e.g., SURFYNOL® SEF from Air Products and Chemicals, Inc., USA), a fluorosurfactant (e.g., CAPSTONE® fluorosurfactants from DuPont, USA), or a combination thereof. In other examples, the surfactant can be an ethoxylated low-foam wetting agent (e.g., SURFYNOL® 440, SURFYNOL® 465, or SURFYNOL® CT-111 from Air Products and Chemical Inc., USA), or an ethoxylated wetting agent and molecular defoamer (e.g., SURFYNOL® 420 from Air Products and Chemical Inc., USA). Still other examples of surfactants can include wetting agents and molecular defoamers (e.g., SURFYNOL® 104E from Air Products and Chemical Inc., USA), alkylphenylethoxylates, solvent-free surfactant blends (e.g., SURFYNOL® CT-211 from Air Products and Chemicals, Inc., USA), water-soluble surfactant (e.g., TERGITOL® TMN-6, TERGITOL® 15S7, and TERGITOL® 15S9 from The Dow Chemical Company, USA), or a combination thereof. In other examples, the surfactant can include non-ionic organic surfactants (e.g., TEGO® Wet 510 from Evonik Industries AG, Germany), non-ionic secondary alcohol ethoxylate (e.g., TERGITOL® 15-S-5, TERGITOL® 15-S-7, TERGITOL® 15-S-9, and TERGITOL® 15-S-30 all from Dow Chemical Company, USA), or a combination thereof. Example anionic surfactants can include alkyldiphenyloxide disulfonate (e.g., DOWFAX® 8390 and DOWFAX® 2A1 from The Dow Chemical Company, USA), oleth-3 phosphate surfactant (e.g., CRODAFOS™ N3 Acid from Croda, UK), and dioctyl sulfosuccinate sodium salt. Example cationic surfactant can include dodecyltrimethylammonium chloride, hexadecyldimethylammonium chloride, or a combination thereof. In some examples, the surfactant can include a co-polymerizable surfactant. Co-polymerizable surfactants can include polyoxyethylene alkylphenyl ether ammonium sulfate, sodium polyoxyethylene alkylether sulfuric ester, polyoxyethylene styrenated phenyl ether ammonium sulfate, or mixtures thereof. The surfactant can be present, when present in the aqueous liquid vehicle, in amounts that can range from about 0.05 wt% to about 10 wt% based on the total weight of the aqueous liquid vehicle. In some examples, the surfactant can be present in an amount ranging from about 0.1 wt% to about 5.0 wt%, 0.05 wt% to about 2.5 wt%, about 5 wt% to about 10 wt%, or about 2.5 wt% to about 7.5 wt% based on the total weight of the aqueous liquid vehicle. [0033] In some examples, the aqueous liquid vehicle may include a colorant. The colorant may be used to visually identify a location of the barrier valve formulation when applied to a self-wicking porous substrate. The colorant can include a pigment and/or a dye colorant. The colorant may be present in the aqueous liquid vehicle, when present, at from about 0.05 wt% to about 0.5 wt%. in yet other examples, the colorant can be present in the aqueous liquid vehicle at from about 0,075 wt% to about 0.5 wt% or from about 0.05 wt% to about 0.1 wt%.

[0034] In some examples, the aqueous liquid vehicle can further include a pH adjustor. A pH adjuster may include sodium hydroxide, potassium hydroxide, ammonia, hydrochloric acid, nitric acid, sulfuric acid, and (poly)alkanolamines such as triethanolamine and 2-amino-2-methyl-1 -propaniol, phosphate, Tris, HEPES (4-(2-hydroxyethyl)-1 -piperazineethanesulfonic acid), MOPS (3-(N-morpholino)propanesulfonic acid), or mixtures thereof. In some examples, the pH adjuster can provide a buffered solution to control the pH of the barrier valve formulation.

[0035] In some examples, the kit can further include additional barrier valve formulations, such as, a second barrier valve formulation, a third barrier valve formulation, or a fourth barrier valve formulation. A second barrier valve formulation can include for example, from about 1 wt% to about 20 wt% of a second hydrophobic material dispersed or dissolved in a second aqueous liquid vehicle including water and from about 5 wt% to about 30 wt% of a second organic co-soivent having a second negative partition coefficient that can be different than the negative partition coefficient of the organic co-solvent of other barrier valve formulations in the kit. The second, third, and fourth barrier valve formulations can be as described above. The differences between the additional barrier valve formulations may be based on the organic co-solvent and specifically the negative partition co-efficient of the organic co-solvent. A purpose of the additional barrier valve formulations is to form additional barrier valves that can degrade at different rates when contacted by a fluid flowing through the self-wicking porous substrates. Accordingly, the second, third, and fourth hydrophobic materials, and aqueous liquid vehicles, other than the organic co-solvent, may be the same or different from the hydrophobic material and aqueous liquid vehicle of the barrier valve formulation.

Methods of Forming Fluid Degradable Barrier Valves

[0036] Further presented herein is a method of forming a fluid degradable barrier valve. The method 300 can include selectively dispensing 310 a barrier valve formulation from a fluid applicator to penetrate a self-wicking porous substrate and form a fluid degradable barrier at the self-wicking porous substrate. The barrier valve formulation can include from about 1 wt% to about 20 wt% of a hydrophobic material dispersed or dissolved in an aqueous liquid vehicle including water and from about 5 wt% to about 30 wt% organic co-solvent having a negative partition coefficient. The barrier valve formulation and the self-wicking porous substrate can be as described above.

[0037] The fluid applicator in further detail can be any type of apparatus capable of selectively dispensing or applying a barrier valve formulation. For example, the fluid applicator could be a sprayer, a dropper, or other similar structure for applying the barrier valve formulation. In yet other examples, the fluid applicator can be a fluid ejector, digital fluid ejector, or a fluidjet ejector, such as an inkjet print head, e.g., a piezo-electric print head, a thermal print head, a continuous print head, etc. In one example, the selective dispensing through the fluid applicator can includes a fluidjet printhead and the barrier valve formulation can have a viscosity suitable to dispense from the fluidjet printhead.

[0038] The selective dispensing can occur at a location of the self-wicking porous substrate that can allow for the formation of a barrier valve. A “barrier valve” as used herein refers to a fluid degradable barrier formed in the self-wicking porous substrate. The barrier valve can be sized, shaped, and located, to allow for control of a residence of time of a fluid in a section of the self-wicking porous substrate, to permit timed merging of multiple fluids from branched pathways that combine to a single linear pathway, to automate the testing multiple samples from divided regions on a seif-wicking porous substrate, and/or to automate washing between multiple or different samples flowed through a self-wicking porous substrate.

[0039] In some examples, the method can further include selectively dispensing a second barrier valve formulation, a third barrier valve formulation, and/or a fourth barrier valve formulation onto the self-wicking porous substrate at an additional location of the self-wicking porous substrate. For example, a second barrier valve formulation can be dispensed at a second location of the self-wicking porous substrate. The second barrier valve formulation can include from about 1 wt% to about 20 wt% of a second hydrophobic material dispersed or dissolved in a second aqueous liquid vehicle including water and from about 5 wt% to about 30 wt% of a second organic co-solvent having a second negative partition coefficient that may be different than the negative partition coefficient of the organic co-solvent of the barrier valve formulation.

[0040] In some examples, the barrier valve formulation may include a relatively high melting point wax, as described above. In those examples, the method can further include curing the barrier valve formulation so that the barrier valve formulation penetrates in the self-wicking porous substrate. The curing may occur by heating the self-wicking porous substrate to a temperature ranging from about 50 °C to about 150 °C for a period of time ranging from about 30 seconds to about 2 minutes. In yet other examples, the curing can occur by heating the self-wicking porous substrate to a temperature ranging from about 100 °C to about 150 °C for about 30 seconds to about 1 minutes or a temperature ranging from about 50 °C to about 100 °C for about 1 minute to about 2 minutes. The temperature and time period may depend on the wax in the barrier valve formulation. In some examples, the heating can occur from above the self-wicking porous substrate using an electromagnetic energy source that can expose the self-wicking porous substrate to radiation energy. The electromagnetic radiation source can be a static lamp or can travel laterally by carriage along with the fluid applicator. The electromagnetic energy source can be selected from a UV LED array, a black light, a shortwave UV lamp, a halogen lamp, a mercury lamp, or a gas discharge lamp. In yet other examples, heat may be applied to the self-wicking porous substrate from below the substrate using a heated platform, a flame, a light source, or the like situated below the self-wicking porous substrate.

Systems for Manufacturing Fluid Degradable Barrier Valves

[0041] Also presented herein is a system for manufacturing a fluid degradable barrier valve of a self-wicking porous substrate, as illustrated in FIG. 4. The system 400 can include a fluidjet ejector 410 to eject a barrier valve formulation from a reservoir 412 when loaded within the reservoir; a barrier valve formulation 200 loaded in or loadable within the fluidjet ejector; and a hardware controller 420 to generate a command to control the fluidjet ejector to apply the barrier valve formulation dropwise onto a self-wicking porous substrate at a user designated location or multiple locations. The fluidjet ejector can be controllable by the hardware controller to eject as little as a single drop of the barrier valve formulation at the user designed location or multiple locations.

[0042] The barrier valve formulation can include from about 1 wt% to about 20 wt% of a hydrophobic material dispersed or dissolved in an aqueous liquid vehicle including water and from about 5 wt% to about 30 wt% organic co-solvent having a negative partition coefficient. The barrier valve formulation can be as described above.

[0043] The fluidjet ejector in further detail can include a reservoir that can be loadable and may include an opening for loading of a barrier valve formulation therein. The reservoir can accept the barrier valve formulation in fluid format or preloaded onto cartridge strips for printing. The fluidjet ejector can include multiple nozzles per ejector. The nozzles can be fired simultaneously or individually.

[0044] In an example, the fluidjet ejector can be located on a carriage track 414, but could be supported by any of a number of structures. In yet another example, the fluidjet ejector can include a motor and can be operable to move back and forth, and the fluidjet ejector can also be moved front to back as well, to provide both x-axis and y-axis movement over the self-wicking porous substrate when the fluidjet ejector is positioned over or adjacent to a self-wicking porous substrate.

[0045] The hardware controller can include software design to permit customized “dot matrix”-type patterns for printing the barrier valve formulation on the self-wicking porous substrate. The hardware controller can provide for specific drop weight, drop velocity, firing frequency, and the like for application of the barrier valve formulation to the self-wicking porous substrate. The hardware controller can allow for single firing from nozzles of the fluidjet ejector or simultaneous firing from nozzles of the fluidjet ejector.

[0046] In further detail, the kits shown at FIGS. 1 and 2, the method shown at FIG. 3, and the system shown at FIG. 4 can be used to form a self-wicking device for detecting the presence (or lack thereof) of an analyte in a sample fluid. For example, the barrier valve formulation can be applied to the self-wicking porous substrate to form the self-wicking device, e.g., the self-wicking porous substrate with a fluid degradable barrier valve thereon. With this device, the fluid degradable barrier valve can control fluid flow through the self-wicking porous substrate. The barrier valve formulation can be applied to form fluid degradable barrier valves that can allow for controlled residence time by holding a fluid in a region of the self-porous wicking substrate for a period of time necessary to degrade a fluid degradable barrier valve that blocks fluid flow to other regions of the substrate, to permit timed merging of different fluids flowing through a self-wicking porous substrate, to automate the testing of multiple fluid samples along a self-wicking porous substrate including multiple fluid flow paths, to allow for automated washing of the self-wicking porous substrate between tests, or a combination thereof.

Definitions

[0047] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise.

[0048] As used herein, the term “about” is used to provide flexibility to a numerical range endpoint by providing that a given value may be a little above' or “a little below” the endpoint. The degree of flexibility of this term can be dictated by the particular variable and determined based on experience and the associated description herein.

[0049] As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on presentation in a common group without indications to the contrary.

[0050] Concentrations, dimensions, amounts, and other numerical data may be presented herein in a range format. A range format is used merely for convenience and brevity and should be interpreted flexibly to include the numerical values explicitly recited as the limits of the range, and also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a numeric range that ranges from about 10 to about 500 should be interpreted to include the explicitly recited sub-range of about 10 to about 500 as well as sub-ranges thereof such as about 50 and about 300, as well as sub-ranges such as from about 100 to about 400, from about 150 to about 450, from about 25 to about 250, etc.

[0051] The terms, descriptions, and figures used herein are set forth by way of illustration and are not meant as limitations. Many variations are possible within the disclosure, which is intended to be defined by the following claims and equivalents in which all terms are meant in the broadest reasonable sense unless otherwise indicated.

Example Preparation of Barner Valve Formulations and Evaluation

[0052] Multiple barrier valve formulations were prepared by admixing the ingredients indicated in Table 1.

The barrier valve formulations were then respectively dispensed in circular patterns of equal size onto a single nitrocellulose self-wicking porous membrane. Each of the self-wicking porous membranes with the barrier valve formulation thereon was dipped in blue-dyed water until the blue-dyed water reached the other end of the self-wicking porous wicking membrane. The barrier valves were then visually inspected for degradation. Formulation 1 formed a short time fluidic valve which was quickly broken by the blue-dyed water. Formulation 2 formed a long time fluidic valve which was slowly broken by the blue-dyed water.

Formulation 3 formed a barrier which could not be broken by the blue-dyed water.

[0053] The results indicate that incorporating an organic co-solvent having a negative partition coefficient in the barrier valve formulation can permit the formation of barrier valves which can be degraded by aqueous fluids passing through a self-wicking porous substrate; whereas, incorporating an organic co-solvent having a positive partition coefficient in a barrier valve formulation results in a barrier that cannot be degraded by an aqueous fluid passing through a self-wicking porous substrate.

[0054] While the present technology has been described with reference to certain examples, it is appreciated that various modifications, changes, omissions, and substitutions can be made without departing from the spirit of the disclosure. It is intended, therefore, that the disclosure be limited only by the scope of the following claims.

Claims

CLAIMS What is Claimed Is:

1. A kit for forming a fluid degradable barrier valve, comprising; a self-wicking porous substrate; and a barrier valve formulation to apply to the self-wicking substrate, the barrier valve formulation including from about 1 wt% to about 20 wt% of a hydrophobic material dispersed or dissolved in an aqueous liquid vehicle including water and from about 5 wt% to about 30 wt% organic co-solvent having a negative partition coefficient.

2. The kit of claim 1 , wherein the self-wicking porous substrate includes nitrocellulose, cellulose, acetate cellulose, fiberglass, porous silica, polyester, surface modified polyester, hydrogel, nylon, polytetrafluorethylene, silica, or a combination thereof.

3. The kit of claim 1 , wherein pores of the self-wicking porous substrate have an average pore size ranging from about 500 nm to about 50 pm.

4. The kit of claim 1 , wherein the hydrophobic material includes a paraffin wax, a polyethylene wax, a fluorothermoplastic, a latex, or a combination thereof.

5. The kit of claim 1 , wherein the hydrophobic material is dispersed in the aqueous liquid vehicle and has a D50 particle size in a range of from about 80 nm to 300 nm.

6. The kit of claim 1 , wherein the organic co-solvent is selected from glycerol, 2-pyroolidone, acetamide, methanol, formic acid, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, polypropylene glycol, formic acid, acetic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, mixtures or combinations thereof.

7. The kit of claim 1 , wherein the organic co-solvent is hydrophobic.

8. The kit of claim 1 , wherein the negative partition coefficient of the organic co-solvent ranges from about -2.0 to about -0.5.

9. The kit of claim 1 , further comprising a second barrier valve formulation including from about 1 wt% to about 20 wt% of a second hydrophobic material dispersed or dissolved in a second aqueous liquid vehicle including water and from about 5 wt% to about 30 wt% of a second organic co-solvent having a second negative partition coefficient that is different than the negative partition coefficient of the organic co-solvent.

10. A method of forming a fluid degradable barrier valve, comprising selectively dispensing a barrier valve formulation from a fluid applicator to penetrate a self-wicking porous substrate and form a fluid degradable barrier at the self-wicking porous substrate, wherein the barrier valve formulation includes from about 1 wt% to about 20 wt% of a hydrophobic material dispersed or dissolved in an aqueous liquid vehicle including water and from about 5 wt% to about 30 wt% organic co-solvent having a negative partition coefficient.

11 . The method of claim 10, wherein fluid applicator includes a fluidjet printhead, wherein the barrier valve formulation has a viscosity suitable to dispense from the fluidjet printhead.

12. The method of claim 10, further comprising selectively dispensing a second barrier valve formulation onto the porous substrate at a second location of the self-wicking porous substrate, wherein the second barrier valve formulation includes from about 1 wt% to about 20 wt% of a second hydrophobic material dispersed or dissolved in a second aqueous liquid vehicle including water and from about 5 wt% to about 30 wt% of a second organic co-solvent having a second negative partition coefficient that is different than the negative partition coefficient of the organic co-solvent.

13. The method of claim 10, further comprising curing the barrier valve formulation that is penetrated in the self-wicking porous substrate by heating the self-wicking porous substrate to a temperature ranging from about 50 °C to about 150 °C for a period of time ranging from about 30 seconds to about 2 minutes.

14. A system for manufacturing a fluid degradable barrier valve of a self-wicking porous substrate, comprising: a fluidjet ejector to eject a barrier valve formulation from a reservoir when loaded therein; a barrier valve formulation loaded in or loadable within the reservoir, wherein the barrier valve formulation includes from about 1 wt% to about 20 wt% of a hydrophobic material dispersed or dissolved in an aqueous liquid vehicle including water and from about 5 wt% to about 30 wt% organic co-solvent having a negative partition coefficient; and a hardware controller to generate a command to control the fluidjet ejector to apply the barrier valve formulation dropwise onto a self-wicking porous substrate at a user-designated location or multiple locations, wherein the fluidjet ejector is controllable by the hardware controller to eject as little as a single drop of the barrier valve formulation at the user designed location or multiple locations.

15. The system of claim 14, further comprising, a second fluidjet ejector to eject a second barrier valve formulation from a second reservoir when loaded therein; and a second barrier valve formulation loaded in or loadable within the second fluidjet ejector, wherein the second barrier valve formulation includes from about 1 wt% to about 20 wt% of a second hydrophobic material dispersed or dissolved in a second aqueous liquid vehicle including water and from about 5 wt% to about 30 wt% of a second organic co-solvent having a second negative partition coefficient that is different than the negative partition coefficient of the organic co-solvent.