Microfluidic Paper Sensors for Controlled Substances
Forensic investigations would benefit from the development of a hand-held sensor for drug detection. Reliance on off-site laboratory analysis creates feedback delay. Small, 2D sensors were made by waxing chromatography paper and then heating to create hydrophobic barriers in the paper. Sensors with hydrophobic channels leading to multiple reagent zones were created by patterning the wax. Repeated trials yielded devices 2.9 cm or less in diameter. These sensors were successfully adapted to test for caffeine, cocaine, and barbiturates by applying appropriate colorimetric reagents.