Sensor Wipe For Detecting Surface Conditions

Abstract

A sensor wipe, made in part by a hydroentangling or conforming process, includes fibers onto which an indicator dye is immobilized. The substrate may be used to make sensor wipes for testing surface conditions, including but not limited to pH or the presence of certain microbes. The indicator dye does not leach from the sensor wipe. The indicator dye may be reversible so that the sensor wipe can be reused prior to disposal.

1 . A method of manufacturing sensor sheets comprising the steps of:
 preparing indicator fibers by immobilizing an indicator dye onto paper-making fibers, wherein the step of immobilizing comprises the act of combining the indicator dye with oppositely charged papermaking-fibers;   preparing a pulp slurry by combining the indicator fibers with an aqueous solution;   creating a web from the pulp slurry;   hydroentangling or coforming the web with a synthetic polymer; and   converting the hydroentangled or coformed web to create a plurality of sensor sheets.   
     
     
         2 . The method of  claim 1  wherein the indicator dye is immobilized onto the paper-making fibers by covalent bonds. 
     
     
         3 . The method of  claim 1  wherein the indicator dye comprises a pH indicator dye. 
     
     
         4 . The method of  claim 1  wherein the indicator dye comprises a redox dye. 
     
     
         5 . The method of  claim 1  wherein the indicator dye comprises a metal sensitive dye. 
     
     
         6 . The method of  claim 1  wherein the indicator dye comprises an amino acid detection dye. 
     
     
         7 . The method of  claim 1  wherein the sensor sheet comprises 10 percent to 25 percent by weight of indicator fibers and further comprises other natural fibers. 
     
     
         8 . The method of  claim 1  wherein the sensor sheet comprises 2 percent to 100 percent by weight of indicator fibers and further comprises other natural fibers. 
     
     
         9 . The method of  claim 1  wherein the paper-making fibers are derived from natural cellulosic fibers. 
     
     
         10 . The method of  claim 1  wherein the paper-making fibers are derived from cotton, abaca, kenaf, sabai grass, flax, ramie, esparto grass, straw, jute, industrial hemp, bagasse, milkweed floss, pineapple leaves and a combination thereof. 
     
     
         11 . The method of  claim 1  wherein the paper-making fibers are comprised of softwood fibers and/or hardwood fibers. 
     
     
         12 . The method of  claim 1  wherein the paper-making fibers are comprised of recycled fibers. 
     
     
         13 . The method of  claim 1  wherein the paper-making fibers are comprised of synthetic cellulosic fibers. 
     
     
         14 . A method of manufacturing a pH indicating sensor sheet comprising the steps of:
 (a) immobilizing a charged pH indicator dye onto oppositely charged cellulose fibers to create indicator fibers;   (b) preparing a pulp slurry by combining the indicator fibers with a pulp solution;   (c) preparing a web comprising indicator fibers; and   (d) hydroentangling or coforming the web with a polymer.   
     
     
         15 . The method of  claim 14  wherein the polymer comprises polypropylene and wherein the ratio of indicator fibers to the polypropylene is 80:20. 
     
     
         16 . The method of  claim 14  wherein the pH indicator dye comprises 4-anilino-3″-azobenzene, which turns deep purple in the pH range of 0-4.5. 
     
     
         17 . The method of  claim 14  wherein the pH indicator dye comprises 4-anilino-3′-azobenzene, which turns deep purple in the pH range of 0-3. 
     
     
         18 . The method of  claim 14  wherein the pH indicator dye comprises a 1:1:3 weight ratio of 4-anilino-3-azobenzene, 2-(2,4-dinitrophenylazo)-4-naphthol-sulphonic acid, and 4-methylamido-2-dimethylaminobenzene sulfonic acid; wherein the pH indicator dye turns from yellow to green in the pH range of 2-3. 
     
     
         19 . The method of  claim 14  wherein the pH indicator dye comprises bromocresol green, bromothymol blue or a combination thereof.