A device comprising a sample pad for Lateral Flow Assay and a test strip for LFAbeing prepared by a process comprising the following steps: i. Preparing a sample pad for lateral Flow Assay by: a) pipetting aqueous two phase system (ATPS) components onto a fiberglass porous paper, wherein the ATPS components comprise 20% (w/w) polyvinyl pyrrolidone and 18.5%(w/w) sodium cholate; b) drying the fiberglass porous paper in a lyophilizer; c) pipetting a 10% (w/w) solution of dextran onto one end of the fiberglass porous paper so that the dextran is present in a gradient concentration along a diffusion direction; d) adding a polyethylene glycol solution to the fiberglass porous paper; e) adding 50 μl of a Tris-buffered solution containing 2% bovine serum albumin, and 0.1% PEG, 20 mM Tris pH 7.5 onto the fiberglass porous paper adjacent to where the 10% (w/w) solution of dextran was applied; f) drying the fiberglass porous paper in a lyophilizer; g) placing the fiberglass porous paper in a colloidal gold buffer solution in phosphate-buffered saline; h) placing the fiberglass porous paper under vacuum to dehydrate; ii. Prepating a lateral flow assay TEST strip by: i) adding anti-S. mutans antibody at a concentration of 1 mg/mL and protein at a concentration of 0.2 mg/ml onto a lateral flow assay test strip consisting of untreated paper; j) conjugating colloidal gold nanoparticles to anti-S. mutans antibody to form a conjugate; k) drying the conjugate onto the conjugated pad material of the LFA test strip using a lyophilizer; and iii. integrating the LFA test strip with the sample pad of LFA together into a housing to form the device. i. Preparing a sample pad for lateral Flow Assay by: a) pipetting aqueous two phase system (ATPS) components onto a fiberglass porous paper, wherein the ATPS components comprise 20% (w/w) polyvinyl pyrrolidone and 18.5%(w/w) sodium cholate; b) drying the fiberglass porous paper in a lyophilizer; c) pipetting a 10% (w/w) solution of dextran onto one end of the fiberglass porous paper so that the dextran is present in a gradient concentration along a diffusion direction; d) adding a polyethylene glycol solution to the fiberglass porous paper; e) adding 50 μl of a Tris-buffered solution containing 2% bovine serum albumin, and 0.1% PEG, 20 mM Tris pH 7.5 onto the fiberglass porous paper adjacent to where the 10% (w/w) solution of dextran was applied; f) drying the fiberglass porous paper in a lyophilizer; g) placing the fiberglass porous paper in a colloidal gold buffer solution in phosphate-buffered saline; h) placing the fiberglass porous paper under vacuum to dehydrate; a) pipetting aqueous two phase system (ATPS) components onto a fiberglass porous paper, wherein the ATPS components comprise 20% (w/w) polyvinyl pyrrolidone and 18.5%(w/w) sodium cholate; b) drying the fiberglass porous paper in a lyophilizer; c) pipetting a 10% (w/w) solution of dextran onto one end of the fiberglass porous paper so that the dextran is present in a gradient concentration along a diffusion direction; d) adding a polyethylene glycol solution to the fiberglass porous paper; e) adding 50 μl of a Tris-buffered solution containing 2% bovine serum albumin, and 0.1% PEG, 20 mM Tris pH 7.5 onto the fiberglass porous paper adjacent to where the 10% (w/w) solution of dextran was applied; f) drying the fiberglass porous paper in a lyophilizer; g) placing the fiberglass porous paper in a colloidal gold buffer solution in phosphate-buffered saline; h) placing the fiberglass porous paper under vacuum to dehydrate; ii. Prepating a lateral flow assay TEST strip by: i) adding anti-S. mutans antibody at a concentration of 1 mg/mL and protein at a concentration of 0.2 mg/ml onto a lateral flow assay test strip consisting of untreated paper; j) conjugating colloidal gold nanoparticles to anti-S. mutans antibody to form a conjugate; k) drying the conjugate onto the conjugated pad material of the LFA test strip using a lyophilizer; and i) adding anti-S. mutans antibody at a concentration of 1 mg/mL and protein at a concentration of 0.2 mg/ml onto a lateral flow assay test strip consisting of untreated paper; j) conjugating colloidal gold nanoparticles to anti-S. mutans antibody to form a conjugate; k) drying the conjugate onto the conjugated pad material of the LFA test strip using a lyophilizer; and iii. integrating the LFA test strip with the sample pad of LFA together into a housing to form the device.