BACKGROUND

[0001] Inkjet printing is a printing technique for printing images, characters, symbols, and/or other information on a substrate. Inkjet printers can form ink droplets using heat and/or mechanical vibration. For instance, a thermal inkjet printer can include a resistor that creates heat to vaporize fluid in a nozzle to create a bubble. As the bubble expands, some of the ink can be pushed out of the nozzle and onto a substrate. DETAILED DESCRIPTION

[0002] Inkjet printing can be used to form an object For instance, inkjet printing can be used to form a portion of an immunoassay on a substrate. Immunoassays can be used in various life sciences applications. A lateral flow assay (LFA) is an example of an immunoassay. Immunoassays such as a LfA can be designed with particular physical structures to provide specific flow parameters depending upon an intended application of the immunoassay. Immunoassays with consistent physical structures and/or uniform flow parameters may be desirable to ensure the immunoassays functions as intended.

[0003] In addition, inkjet printing with bio-compatible and/or environmentally-friendly fluids can be desirable. As used herein, being bio-compatible refers to a material that does not alter or otherwise negatively affect biomolecules, such as proteins or antibodies. In contrast,acids or other non-biocompatible materials can alter or damage a biomolecule. For example, an add can denature a protein. As used herein, being environmentally-friendly refers to a fluid that is fine of harsh organic solvents and does not indude extra components (such as binders) that may not be biodegradable. As used herein, a harsh organic solvent refers to solvents that indude volatile organic compounds (VOCs).

[0004] Some printing methods may rely on a heated and liquified material, such a wax that is printed while heated and liquified. However, such approaches therefore can inherently be subject to reproducibility errors and inconsistendes due to use of the heated and liquefied material Some other printing methods approaches employ adds, colorants, binders, harsh organic solvents, and/or other non-biocompatible/non-environmentally friendly components. [0005] As such, the disclosure is directed to inkjet compositions, as detailed herein. For instance, in some examples, an inkjet composition can include an aqueous solvent present in an amount of from about 1.0 wt% to about 99.0 weight percent (wt%) based on a total weight of the inkjet composition, and a wax present in an amount from about from about 0.1 to about 10.0 wt% based on the total weight of the composition.

[0006] Notably, the inkjet compositions herein can be bio-compatible and/or environmentally-friendly inkjet compositions. For instance, in some examples the inkjet compositions are both bio-compatible and environmentally-friendly inkjet composition, as described herein, and yet are suitable for inkjet printing and use with immunoassays. For instance, the inkjet compositions herein can be employed to in an inkjet printer to form a portion of an immunoassay with uniform flow parameters that are suitable for use in life sciences applications.

[0007] Inkjet composition

[0008] In some example, an inkjet composition can include an aqueous solvent present in an amount of from about 1.0 wt% to about 99.0 wt% based on a total weight of the inkjet composition, and a wax present in an amount from about from about 0.1 to about 10.0 wt% based on the total weight of the composition. In some examples an inkjet composition can consist essentially of an aqueous solvent present in an amount of from about 1.0 wt% to about 99.0 wt% based on a total weight of the inkjet composition; and a wax present in an amount from about 0.1 to about 10.0 wt% based on the total weight of the composition. In such examples, the inkjet composition that consists essentially of the aqueous solvent and the wax, as detailed above, can further include a surfactant, co-solvent, and/or an additive such as those described herein.

[0009] In some examples, an inkjet composition can include an aqueous solvent present in an amount of from about 1.0 to about 80.0 wt% based on a total weight of the inkjet composition, a co-solvent present in an amount of from about 1.0 to about 20.0 wt% based on the total weight of the inkjet composition, a wax present in an amount from about from about 1.0 to about 20.0 wt% based on the total weight of the inkjet composition, and a surfactant that is optionally present in an amount from about 0 to 10.0 wt% based on the total weight of the inkjet composition. In some examples, an inkjet composition can include an aqueous solvent present in an amount of from about 1.0 to about 80.0 wt % based on a total weight of the inkjet composition, a co-solvent present in an amount of from about 1.0 to about 20.0 wt% based on the total weight of the inkjet composition, a wax present in an amount from about from about 1.0 to about 20.0 wt% based on the total weight of the inkjet composition, and a surfactant present in an amount from about 0 to 10.0 wt% based on the total weight of the inkjet composition. In some examples an inkjet composition can consist essentially of a aqueous solvent present in an amount of from about 1.0 to about 80.0 wt% based on a total weight of the inkjet composition, a co-solvent present in an amount of from about 1.0 to about 20.0 wt% based on the total weight of the inkjet composition, a wax present in an amount from about 1.0 to about 20.0 wt% based on the total weight of the inkjet composition; and a surfactant present in an amount from about 0.1 to 10.0 wt% based on the total weight of the inkjet composition.

In such examples, the inkjet composition that consists essentially of the aqueous solvent, cosolvent, wax, and surfactant, as detailed above, can further include an additive such as those described herein.

[0010] In some example, an inkjet composition can include an aqueous solvent present in an amount of from about 1.0 wt% to about 99.0 wt% based on a total weight of the inkjet composition, and a wax present in an amount from about from about 0.1 to about 10.0 wt% based on the total weight of the composition. In some examples an inkjet composition can consist essentially of an aqueous solvent present in an amount of from about 1.0 wt% to about 99.0 wt% based on a total weight of the inkjet composition, and a wax present in an amount from about from about 0.1 to about 10.0 wt% based on the total weight of the composition. [0011] AQUEOUS SOLVENT

[0012] In various examples the inkjet compositions can include an aqueous solvent Examples of aqueous solvents include as water, deionized water, distilled water, or otherwise purified (filtered) water. In some examples the aqueous solvent can be selected from a group consisting of water, deionized water and distilled water. In some examples, the aqueous solvent can consist of water. In some examples, the aqueous solvent can consist of de-ionized water. In some examples, the aqueous solvent can consist of distilled water.

[0013] In some examples, the aqueous solvent can be present in an amount of from about 1.0 wt% to about 99.0 wt% based on a total weight of the inkjet composition. In some examples, the aqueous solvent in amounts to make up the balance of the inkjet composition. In some examples, the aqueous solvent can be present in the inkjet compositions in amounts greater than about 50.0 wt% based on the total weight of the inkjet composition. In some examples, the aqueous solvent can be present in the inkjet compositions in amounts from about 50.0 wt% to about 99.0 wt% based on the total weight of the inkjet composition. In some examples, the inkjet composition can include from about 60.0 wt% to about 97.4 wt% aqueous solvent. In further examples, the inkjet composition can include from about 70.0 wt% to about 90.4 wt% aqueous solvent. In some examples, the inkjet composition can include from about 70.0 wt% to about 87.6 wt% aqueous solvent. In some examples, the inkjet composition can include from about 97.4 wt% aqueous solvent. In some examples, the inkjet composition can include from about 90.4 wt% aqueous solvent [0014] Co-Solvent

[0015] In some examples, the inkjet compositions can include a co-solvent [0016] In some examples, the co-solvent can be present in an inkjet composition in an amount of from about 1.0 wt% to about 20.0 wt% based on the total weight of the inkjet composition. In some examples, the co-solvent can be present in the inkjet composition in an amount of from about 3.0 wt% to about 12.0, from about 5.0 wt% to about 10.0 wt%, or from about 5.0 wt% to about 7.0 wt% based on the total weight of the inkjet composition. In some examples, the inkjet composition can include from about 7.0 wt% co-solvent In some examples, the inkjet composition can include about 0.0 wt% co-solvent [0017] Examples of suitable co-solvents include aliphatic alcohols, aromatic alcohols, diols, triols, glycol ethers, poly(glycol) ethers, lactams, formamides, acetamides, long chain alcohols, ethylene glycol, propylene glycol, diethylene glycols, triethylene glycols, glycerine, dipropylene glycols, glycol butyl ethers, polyethylene glycols, polypropylene glycols, amides, ethers, carboxylic acids, esters, organosulfides, organosulfoxides, sulfones, alcohol derivatives, carbitol, butyl carbitol, cellosolve, ether derivatives, amino alcohols, and ketones. For example, co-solvents can include primary aliphatic alcohols of 30 carbons or less, primary aromatic alcohols of 30 carbons or less, secondary aliphatic alcohols of 30 carbons or less, secondary aromatic alcohols of 30 carbons or less, 1,2-diols of 30 carbons or less, 1,3-diols of 30 carbons or less, 1,5-diols of 30 carbons or less, ethylene glycol alkyl ethers, propylene glycol alkyl ethers, poly(ethylene glycol) alkyl ethers, higher homologs of poly(ethylene glycol) alkyl ethers, poly(propylene glycol) alkyl ethers, higher homologs of polypropylene glycol) alkyl ethers, lactams, substituted formamides, unsubstituted formamides, substituted acetamides, and unsubstituted acetamides.

[0018] Specific examples of certain co-solvents include hydantoin glycol (such as, e.g., l,3-bis-(2-hydroxyethyl)-5,5-dimethylhydantoin), 1 -(2-hy droxyethy l)-2-pyrrolidinone, l-(2- hydroxyethyl)-2-imidazolidinone, tetratethylene glycol, 1,2,6-hexanetriol, glycerol, glycerol propoxylate, 1,5-pentanediol, LIPONIC® ethoxy lated glycerol 1 (LEG-1), LIPONIC® ethoxylated glycerol 7 (LEG-7), 2-methyl-2,4-pentanediol, 2-methyl-l ,3-propanediol, 2-ethyl- 2-hydroxymethyl-l, 3 -propanediol, diethylene glycol, 3-methoxybutanol, propylene glycol monobutyl ether, l,3-dimethyl-2-imidazolidinone, the like, or combinations thereof.

[0019] In some examples, the co-solvent can refer to a non-aqueous solvent such as glycerol or dimethylsulfoxide (DMSO). For instance, in some examples, the co-solvent can be selected from a group consisting of glycerol and dimethylsulfoxide (DMSO). In some example, the co-solvent can consist of glycerol. In some examples, the co-solvent can consist of DMSO. [0020] Without wishing to be bound by theory, it is believed that co-solvents can be added to reduce the rate of evaporation of water in the inkjet, to minimize clogging, or contribute to other improved properties related to viscosity, pH, surface tension, optical density, gamut, durability, decap, and print quality, for example.

[0021] Wax

[0022] In various examples, an inkjet composition can include a wax. In some examples the wax can selected from a group consisting of a paraffin wax, a polyethylene wax, a fluorothermoplastic, and combinations thereof. The wax can be a wax emulsion. Wax emulsions are commercially available from a number of vendors, for example Keim- Additec, Lubrizol, Michelman, and BYK Chemie. Specific examples of wax emulsions include: Lubrizol: LIQUILUBE™ 411, LIQUILUBE™ 405, LIQUILUBE™ 488, LIQUILUBE™ 443, LIQUILUBE™ 454; Michelman: ME80825, ME48040, ME98040M1, ME61335, ME90842, ME91240, ML 160; Keim-Additec: ULTRALUBE® E-521/20, ULTRALUBE® E-7093, ULTRALUBE® 7095/1, ULTRALUBE® E-8046, ULTRALUBE® E-502V, ULTRALUBE® E-842N: Byk: AQUACER® 2650, AQUACER® 507, AQUACER® 533, AQUACER® 515, AQUACER® 537, AQUASLIP™ 671, AQUASLIP™ 942.

[0023] In some examples, a wax can be present in the inkjet compositions in an amount in a range of from about 0.1 wt% to about 10.0 wt% or from based on the total weight of the inkjet composition. In some examples, the inkjet composition can include wax in an amount ranging from about 0.1 wt% to about 5.0 wt%, 0.1 to about 3.0 wt%, about 0.1 wt% to about 2.0 wt%, or about 0.1 wt% to about 1.0 wt%, based on the total weight of the inkjet composition. In some examples, the inkjet composition can include wax present at about 2.5 wt% based on the total weight of the inkjet composition.

[0024] In some examples, the wax can be formed of particles with a median particle diameter in a range of from about 0.01 microns to 2.0 microns. In some examples, the wax can be formed of particles with a median particle diameter in a range of from about 0.09 microns to 1.0 microns. In some wax can by formed of particles with a median particle diameter in a range of from about 0.09 microns to 0.30 microns. In some wax can by formed of particles with a median particle diameter in a range of from about 0.09 microns to 0.20 microns.

[0025] In some examples, the wax can have a melting temperature in a range from 100 to 350 degrees Celsius (°C). In some examples, the wax has a melting temperature in a range from 100 to 180 °C. That is, the wax herein may have a relatively high melting temperature in contrast to approaches that rely on materials (e.g., wax) with lower melting points that can be readily heated and liquified in advance of application (e.g., printing) of the materials. In some examples, the wax can have a melting temperature in a range from about 105 °C to about 306 °C. In some examples the wax can have a melting temperature of about 306 °C, about 110 °C, or about 105 °C,

[0026] Surfactant

[0027] In some examples, an inkjet composition can include a surfactant. The surfactants in the inkjet compositions can include non-ionic, cationic, and/or anionic surfactants.

[0028] The surfactant can be present in amounts ranging from about 0.1 wt% to about 10.0 wt% based on the total weight of the inkjet composition. In some examples, the surfactant can be present in an amount ranging from about 0.1 wt% to about 5.0 wt% based on the total weight of the inkjet composition. In some examples, the surfactant can be present at about 0.1 wt% based on the total weight of the inkjet composition.

[0029] In some examples, the inkjet compositions can include ethoxylated alcohols as a surfactant such as those from the Tergitol® series (e.g., Tergitol® 15S30, or Tergitol® 15S9), manufactured by The Dow Chemical Company; surfactants from the Surfynol® series (e.g., Surfynol® 104, Surfynol® 440 and Surfynol® 465), and Dynol™ series (e.g., Dynol™ 360, Dynol™ 604, and Dynol™ 607) manufactured by Air Products and Chemicals, Inc.

[0030] In some examples, the inkjet composition can include a polysorbate surfactant. Examples of polysorbate surfactants include Polysorbate 20 (or polyoxyethylene 20 sorbitan monolaurate), Polysorbate 40 (or polyoxyethylene 20 sorbitan monopalmitate), Polysorbate 60 (or polyoxyethylene 20 sorbitan monostearate), Polysorbate 80 (or polyoxyethylene 20 sorbitan monooleate), or the like. Other polysorbates can likewise be used, including Polysorbate 85, or Tween® 85, which is polyethylene glycol sorbitan trioleate; or Polysorbate 81, Tween® 81, which is a polyoxyethylene (5) sorbitan monooleate, or Tween® 20 which is a polyoxyethylenesorbitan monolaurate. Polyoxyethylene sorbitan dioleate can also be used.

[0031 ] In some examples, the surfactant can be a polyoxyethylene glycol ethers.

Examples such surfactants that can be used include Brij® S, Brij® O, Brij® C, and Brij®

L type surfactants Synperonic surfactants can also be used. Specific examples include Brij® S10, Brij® S5, Brij®, SI 5, Brij® S20, Brij® S2/93, Brij® S7, Brij® 98/020, Brij® O10, Brij® 35, Brij® 02, Brij®, 03, Brij® 05, Brij® C2, Brij® C7, Brij® CIO, Brij®, C20, Brij® L4/30, Brij® L9, Brij® LI 5, Synperonic® 91-2.5, Synperonic® 91-2.5, Synperonic® 91-10, or mixtures thereof. In some examples, the surfactant can be TRITION™ XI 00, which is a polyethylene glycol tert-octylphenyl ether surfactant manufactured by Air Products and Chemicals, Inc.

[0032] In some examples, the surfactant can be bio-compatible surfactant such as Brij® 35, Tween® 20 and/or Triton® X-100, among other bio-compatible surfactants.

[0033] Acid-free [0034] In various examples, the inkjet compositions herein are acid-free. Examples of acids include hydrochloric acid, sulphuric acid, sulphurous acid, phosphoric acid, citric acid, oxalic acid, acetic acid, formic acid, sulphamic acid, tartaric acid, phytic acid, boric acid, succinic acid, suberic acid, and/or benzoic acid, among other types of acids. In some examples, an acid can have a PH of less than about 7.0.

[0035] Colorant-free

[0036] In various examples, the inkjet compositions herein are colorant-free. As used herein, a colorant can include inorganic pigments, organic pigments, dyes, and combinations thereof. The colorant can be any color. In some examples, a colorant can be selected from a group consisting of pigments, organic pigments, dyes, and combinations thereof.

[0037] Binder-free

[0038] In various examples, the inkjet compositions herein are binder-free. Examples of binders include polymer-based binders and polyurethane-based binders that comprise a polyurethane polymer. That is, in some examples the binder-free composition is free of polymer-based binder and polyurethane based binders. As used herein, a polymer-based binder refers to binder that includes a polymer formed of two or more of the same or different polymer units. The polymer can be homopolymers, copolymers, terpolymers, etc. As used herein, a polyurethane polymer can refer to a reaction product of an isocyanate having one or greater numbers of isocyanate ( — NCO) functionalities per molecule with, one or greater isocyanate-reactive groups, such as a polyol, having one or greater hydroxy groups or an amine.

[0039] Bio-compatible and environmentally-friendly inkjet compositions

[0040] As mentioned, the inkjet compositions herein can be bio-compatible and environmentally-friendly due to being acid, colorant, binder, and/or harsh organic solvent-free. In some examples, the inkjet compositions are acid, colorant, binder, and harsh organic solvent-free. As used herein, an absence of an acid, a colorant, a binder, and/or a harsh organic solvent in an inkjet composition can refer to the inkjet compositions including from about 0.0 wt% to about 5.0 wt% independently of each of an acid, a colorant, a binder, and/or a harsh organic solvent Similarly, as used herein an inkjet composition being acid-free, colorant-free, binder-free, and/or harsh organic solvent-free can refer to the inkjet compositions including from about 0.0 wt% to about 5.0 wt% independently of each of an acid, a colorant, a binder, and/or a harsh organic solvent.

[0041] For instance, in some examples, an inkjet compositions can include from about 0.0 wt% to about 5.0 wt%, from about 0.0 wt% to about 3.0 wt%, from about 0.0 wt% to about 1.0 wt%, from about 0.0 wt% to about 0.1 wt%, or 0.0 wt% independently of each of an acid, a colorant, a binder, and a harsh organic solvent based on a total weight of the inkjet composition. In some examples a sum of respective weight percentages of any acid, colorant, binder, and harsh organic solvent present in an inkjet composition is less than about 5.0 wt%, less than about 4.0 wt%, less than about 3.0 wt%, less than about 2.0 wt%, less than 1.0 wt%, or equal to 0.0 wt% based on a total weight of the inkjet composition.

[0042] In some examples, the inkjet composition can include 0.0 wt% acid, colorant, binder, and/or harsh organic solvent in an inkjet composition. For instance, in some examples the each of an acid, a colorant, a binder, and a harsh organic solvent can be present 0.0 wt% based on a total weight of an inkjet composition. Stated differently, in some examples, an inkjet composition can consist of or consist essentially of a given amount of aqueous solvent and wax, as detailed herein. In some examples, an inkjet composition can consist of or consist essentially of a given amount of aqueous solvent, co-solvent, and wax, as detailed herein. In some examples, an inkjet composition can consist of or consist essentially of a given amount of aqueous solvent, co-solvent, wax, and surfactant, as detailed herein. In some examples, an inkjet composition can consist of or consist essentially of a given amount of aqueous solvent, co-solvent, wax, surfactant, and additive, as detailed herein.

[0043] Additive

[0044] The additives in the inkjet compositions can be selected from the group consisting of anti-kogation agents, pH adjusters, antimicrobial agents, sequestering agents, viscosity modifiers, humectants, penetrants, wetting agents, preservatives, jettability additives, and mixtures thereof.

[0045] Kogation refers to the deposit of dried ink on a heating element of a thermal inkjet printhead. An anti-kogation agent can be included to assist in preventing the buildup of kogation. Anti-kogation agents can include an anionic surfactant, a nonionic surfactant, a zwitterionic surfactant, an amphoteric surfactant, or mixtures thereof. A list of surfactants is given above. In some examples, the anti-kogation agents can include oleth-3- phosphate (commercially available as CRODAFOS® 03A or CRODAFOS® N-3 acid) or dextran 500k. The anti-kogation agent can be present in the inkjet composition in an amount ranging from about 0.1 wt% to about 3.0 wt% of the total weight of the inkjet composition.

[0046] A pH adjuster can be added to the inkjet compositions in some examples. A pH adjuster can include sodium hydroxide, potassium hydroxide, ammonia, hydrochloric acid, nitric acid, sulfuric acid, and (poly)alkanolamines such as triethanolamine and 2-amino-2- methyl-l-propaniol, or mixtures thereof.

[0047] In some examples, the inkjet composition can also include an antimicrobial agent. Suitable antimicrobial agents include biocides and fungicides. Examples of antimicrobial agents include ACTICIDE® M20 (i.e., active ingredient is 2-methyl-4- isothiazolin-3-one), ACTICIDE® B20 (i.e., active ingredient is l,2-benzisothiazolin-3- one), AMP (i.e., amino-tris-(methylene phosphonate), TRIS (i.e., tris(hydroxymethyl)nitromethane), and mixtures thereof. Other examples of antimicrobial agent include NUOSEPT® (Ashland Inc.), UCARCIDE™ or KORDEK™ (The Dow Chemical Co.), and PROXEL® (Arch Chemicals) series, and combinations thereof.

[0048] In some examples, sequestering agents can be added to the inkjet compositions. These sequestering agents can be useful to impart improved stability characteristics to the inkjet composition and can include an alkali metal, an alkaline earth metal, and an ammonium salt of a linear aliphatic substituted glycine compound. The term linear aliphatic substituted glycine designates glycine compounds in which the amino group of glycine has been substituted with linear aliphatic groups. In some examples, the sequestering agents can include the alkali metal (e.g., sodium), alkaline earth metal (e.g., calcium) and ammonium salts of ethylene diamine tetraacetic acid, nitrilo triacetic acid, diethylene triamine pentaacetic acid, hydroxyethylene diamine triacetic acid, dihydroxyethyl glycine, iminodiacetic acid and ethanol diglycine. Similar salts of other linear aliphatic substituted glycine compounds can also be used. [0049] In some examples, viscosity modifiers can be added to the inkjet compositions. Examples of viscosity modifiers include aliphatic ketones, stearone, 2-hydroxybenzyl alcohol, 4-hydroxybenzyl alcohol, 4-nitrobenzyl alcohol, 4-hydroxy-3-methoxy benzyl alcohol, 3-methoxy-4-nitrobenzyl alcohol, 2-amino-5-chlorobenzyl alcohol, 2-amino-5- methylbenzyl alcohol, 3-amino-2-methylbenzyl alcohol, 3-amino-4-methyl benzyl alcohol, 2(2-(aminomethyl)phenylthio)benzyl alcohol, 2,4,6-trimethylbenzyl alcohol, 2-amino-2- methyl- 1 ,3 -propanediol, 2-amino- 1 -phenyl- 1 ,3 -propanediol, 2,2-dimethyl- 1 -phenyl- 1,3- propanediol, 2-bromo-2-nitro- 1,3 -propanediol, 3 -tert-butylamino- 1,2-propanediol, 1,1- diphenyl- 1,2-propanediol, l,4-dibromo-2,3-butanediol, 2,3-dibromo-l,4-butanediol, 2,3- dibromo-2-butene-l,4-diol, l,l,2-triphenyl-l,2-ethanediol, 2-naphthalenemethanol, 2- methoxy- 1 -naphthalenemethanol, decafluoro benzhydrol, 2-methylbenzhydrol, 1- benzeneethanol, 4,4'-isopropylidene bis(2-(2,6-dibromo phenoxy)ethanol), 2,2'-(l,4- phenylenedioxy)diethanol, 2,2-bis(hydroxymethyl)-2,2',2"-nitrilotriethanol, di(trimethylolpropane), 2-amino-3 -phenyl- 1 -propanol, tricyclohexylmethanol, tris(hydroxymethyl)aminomethane succinate, 4,4'-trimethylene bis(l -piperidine ethanol), N-methyl glucamine, or mixtures thereof.

[0050] In some examples, the inkjet compositions can also contain penetrants for accelerating penetration of the inkjet composition into the substrate. Suitable penetrants include polyhydric alcohol alkyl ethers (glycol ethers) and/or 1, 2-alky ldiols. Examples of suitable polyhydric alcohol alkyl ethers are ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol mono-isopropyl ether, diethylene glycol mono-isopropyl ether, ethylene glycol mono-n-butyl ether, diethylene glycol mono- n-butyl ether, triethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butyl ether, diethylene glycol mono-t-butyl ether, 1 -methyl- 1-methoxy butanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-t-butyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-isopropyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-isopropyl ether, propylene glycol mono-n-butyl ether, dipropylene glycol mono-n-butyl ether, or combinations thereof. Examples of 1, 2-alky ldiols can include 1,2-pentanediol, 1,2-hexanediol, or combinations thereof. The penetrant can also be selected from straight-chain hydrocarbon diols, such as 1,3 -propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8- octanediol, and combinations thereof.

[0051] In some examples, the inkjet compositions can contain preservatives. Specific examples of preservatives can include dichlorophene, hexachlorophene, 1, 2- benzothiazolin-3-one, 3,4-isothiazolin-3-one, or 4,4-dimethyl oxazolidine, alkyl isothiazolone, chloroalkyl isothiazolone, benzoisothiazolone, bromonitroalcohol, chloroxylenol, or mixtures thereof.

[0052] The additive can be added singularly or in various combinations to the inkjet compositions described herein in total amounts of from about 0.1 wt% to about 10.0 wt% based on the total weight of the inkjet composition.

[0053] Methods of Making Inkjet Compositions

[0054] In some examples, a method of making an inkjet composition is described. The method(s) can comprise mixing an aqueous solvent comprising water in an amount of from about 1.0 wt% to about 99.0 wt% based on the total weight of the inkjet composition, and a wax present in an amount of from about 0.1 wt%. to about 10.0 wt% of the total weight of the inkjet composition to form the inkjet composition. For instance, in some examples the inkjet composition can be co-solvent free and can include from wax present in an amount of from about 0.1 wt%. to about 10.0 wt% to form the inkjet composition and the balance of the inkjet composition can be formed (from 99.9 to 90.0 wt%) of aqueous solvent [0055] However, in some examples a co-solvent can be present For instance, in some examples, the method can comprise mixing a aqueous solvent comprising water in an amount of from about 1.0 wt% to about 99.0 wt% based on the total weight of the inkjet composition, a co-solvent present in an amount of from about 1.0 to about 20.0 wt% based on the total weight of the inkjet composition, and a wax present in an amount of from about 0.1 wt% to about 10.0 wt% of the total weight of the inkjet composition to form the inkjet composition.

[0056] Notably, the methods can make inkjet compositions that are colorant-free, binder- free, and/or harsh organic solvent/acid-free. For instance, the methods can make inkjet compositions can be colorant-free, binder-free, and harsh organic solvent-free. For instance, in some examples the method can include making an inkjet composition by mixing a solvent and the wax together, in an absence of a binder, to form the inkjet composition.

[0057] Using the inkjet compositions

[0058] In some examples, the inkjet compositions described can be used by applying the inkjet compositions to a print media substrate (i.e., substrate). The substrate can be a porous and/or non-porous. In some examples, the substrate is a porous substrate. In some examples, the substrate is a non-porous substrate. In some examples, the substrate can include substrates made from paper, metal, plastic, fabric, or combinations thereof. In some examples, the substrate can include plain papers, glass fiber, cotton linter, nitrocellulose, polycarbonate, polystyrene, polypropylene or other plastics, microporous photopapers, coated papers, glossy photopapers, semi-gloss photopapers, heavy weight matte papers, billboard papers, digital fine art papers, calendared papers, vinyl papers, or combinations thereof, among other possible types of substrates. For instance, in some example the substrate can be nitrocellulose. In some examples, the substrate can be coated and/or treated. For instance, the substrate can be coated and/or treated to increase cell/protein adherence to the coated/treated substrate.

[0059] In some examples, the inkjet composition can be applied to the substrate using any inkjet printer (e.g., thermal or piezoelectric). In some examples, in order to initiate the printing process, a printhead device in an inkjet printer can be activated to deliver an inkjet composition from a cartridge onto a substrate. Activation of the printhead in an inkjet system can involve selective energization of resistors in order to heat the inkjet composition and thereby expel it from the cartridge containing the inkjet composition. If non-thermal-inkjet systems are used to deliver the composition, printhead activation can be accomplished using composition ejectors under consideration, with the procedures associated therewith varying from system to system. [0060] The printing process discussed above is equally applicable to (A) systems in which an inkjet printhead device can be directly attached to a housing in order to form an integral, self-contained cartridge unit having a supply of inkjet composition within the housing; and (B) systems in which the housing and inkjet composition therein are remotely positioned from the printhead and in fluid communication therewith using tubular conduit(s). [0061] Unless otherwise stated, any feature described hereinabove can be combined with any example or any other feature described herein.

[0062] In describing and claiming the examples disclosed herein, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

[0063] It is to be understood that concentrations, amounts, and other numerical data can be expressed or presented herein in range formats. It is to be understood that such range formats are used merely for convenience and brevity and thus should be interpreted flexibly to include not just the numerical values explicitly recited as the end points of the range, but 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. As an illustration, a numerical range of “about 1.0 wt% to about 5.0 wt%” should be interpreted to include not just the explicitly recited values of about 1.0 wt% to about 5.0 wt%, but also include individual values and subranges within the indicated range. Thus, included in this numerical range are individual values such as 2.0, 3.5, and 4.0 and sub-ranges such as from 1.0-3.0, from 2.0-4.0, and from 3.0-5.0, etc. This same applies to ranges reciting an individual numerical value.

[0064] All amounts in the examples below are in wt% unless indicated otherwise. Unless otherwise stated, references herein to “wt %” of a component are to the weight of that component as a percentage of the whole composition comprising that component For example, references herein to “wt%” of, for example, a solid material such as pigment or latex polymer dispersed in a liquid composition are to the weight percentage of those solids in the composition, and not to the amount of that solid as a percentage of the total non-volatile solids of the composition.

[0065] To further illustrate the present disclosure, examples are given herein. It is to be understood that these examples are described for illustrative reasons and are not to be construed as limiting the scope of the present disclosure. That is, while several examples have been described in detail, it is to be understood that the disclosed examples can be modified. Therefore, the description is to be considered non-limiting.

[0066] If a standard test is mentioned herein or not explicated stated for a particular value/measure, unless otherwise stated, the version of the test to be referred to is the most recent at the time of filing this patent application. [0067] As used herein, the term about means that amounts, sizes, formulations, parameters, and other quantities and characteristics are not exact, but can be approximate and/or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art When the term about is used in describing a value or an end-point of a range, the disclosure should be understood to include the specific value or end-point referred to. Whether or not a numerical value or end-point of a range in the specification recites about, the numerical value or end-point of a range is intended to include two examples: one modified by about, and one not modified by about. It will be further understood that the end-points of each of the ranges are significant both in relation to the other end-point, and independently of the other end-point.

EXAMPLES

[0068] Ingredients:

[0069] Aqueous Solvent - Deionized water.

[0070] Co-solvent - (Glycerol >99.5% : sold by Sigma- Aldrich).

[0071 ] Wax - (LIQUILUBE™ 405 Wax (polyethylene wax; sold by Lubrizol Deutschland GmbH).

[0072] Surfactant - (TRITION™ XI 00 - surfactant manufactured by Air Products and Chemicals, Inc.)

[0073] Test methods:

[0074] Testing for inkjet composition compatibility with inkiet printing:

[0075] Compatibility with inkjet printers was tested as follows. Inkjet compositions (e.g., of Example 1 and Example 2) were formed as described herein. The inkjet compositions, once formed, were included in a D300™ inkjet printer (available from HP™). The inkjet compositions were then printed at approximately 15 - 25 nanoliters per spot on a substrate (a porous Grade 1 filter paper available from WHATMAN™ or a porous nitrocellulose membrane available from Thermo Scientific) in a predetermined pattern to form a sample. The sample was then heated to 150 °C on a hot plate for 1 minute. Visual inspection of the substrate then revealed whether the inkjet composition was successfully inkjet printed and present on the sample (i.e., the inkjet composition was compatible for inkjet printing) or whether the inkjet composition was unsuccessful and not present on the substrate. The samples that were compatible for inkjet printing were then tested as follows to determine whether the fluidic structures on the samples were properly formed.

[0076] Testing for successful formation of fluidic structures:

[0077] Successful formation of fluidic structures was tested as follows. Pour approximately 10 millliters (mL) of Pro-Jet Cyan™ 854 (lOOOx dilution in de-ionized water) into a beaker. Place one edge of the sample, formed as detailed above, into the solution. Allow dye to wick- up the sample until it is above the printed portion (on which the inkjet composition was printed). Remove sample from beaker and gently place onto an absorbent material to blot off the excess dye. Observe if the printed portions are dyed. If the printed portions are colored, then the inkjet composition did not work and therefore the inkjet composition was not suitable for fluid routing using this method. Alternatively, if the printed portions are not colored, then the inkjet printing was successful, and the inkjet composition is compatible with this inkjet printing method and the fluidic structures were successfully formed.

[0078] Inkjet compositions were formed as follows.

[0079] Example 1 (EX1)

[0080] The inkjet composition of Example 1 was formed as follows. The respective amounts of the components in Example 1 as illustrated in Table 1 below were mixed together in a vessel at room temperature and pressure to form the inkjet composition of EX1.

[0081] Example 2 (EX2)

[0082] The inkjet composition of Example 2 was formed as follows. The respective amounts of the components in Example 1 as illustrated in Table 1 below were mixed together in a vessel at room temperature and pressure to form the inkjet composition of EX2.

[0084] As indicated in Table 1 , both the inkjet composition of EX1 (without a co-solvent) and the inkjet composition of EX2 (with co-solvent) were compatible with inkjet printing and successfully formed uniform and consistent fluidic structures when printed using an inkjet printer. That is, the inkjet compositions described herein are compatible with inkjet printing,

17 successfully form fluidic structures when printed with an inkjet printer, and, notably, are also bio-compatible and environmentally-friendly endly due to being free of acids, colorants, binders, and harsh organic solvents. For instance, the inkjet compositions of EX1 and EX2 each include 0.0 weight percent of acid, colorant, binder, and harsh organic solvent. Stated differently, the inkjet compositions of EX1 and EX2 do not include any acid, any colorant, any binder, nor any harsh organic solvent [0085] Without wishing to be bound by theory, it is believed that the inkjet compositions herein provide consistent and uniform fluidic structures in portions of immunoassays formed using the inkjet compositions due to the inkjet compositions herein being free of materials such as acids, colorants, binders, and/or harsh organic solvents that, if present, may negatively impact the consistent and reliable formation of fluidic structures. In addition, it is believed that the inkjet compositions herein provided consistent and uniform fluidic structures in portions of immunoassays as the compositions do not rely on melting/liquifying the inkjet compositions herein before printing the inkjet compositions. Moreover, it is believed that the inkjet compositions herein can result in higher press speed, productivity, and suitability for a packaging market, because these inkjet compositions do not result in excessive servicing or other operational items, as compared to other inkjet compositions such as those which employ a heated and liquified material such as a wax, employ wax at a higher relative amount in an mixture, and/or other compositions which employ acids, colorants, binders, and/or harsh organic solvents/acids.