Electrochemical Paper Fluidic Device for Extended Real-time Cocaine Monitoring in Simulated Sweat
Cocaine and other illicit substances are known to excrete from the body into sweat, making sweat an advantageous matrix for non-invasive detection and monitoring of substance use and abuse. However, existing detection of illicit substances in sweat remain single-use technologies that arent suitable for real-time, continuous monitoring over the course of an entire day. Long-term, continuous detection is hampered by large, bulky instrumentation, limited sensor stability for multi-hour measurements, and fluidic systems not optimized for minute and variable sweat flow rates. We demonstrate the continuous detection of 0.5 mM cocaine in simulated sweat via a paper fluidic device over the course of 17 hours. Our sensing system uses a biosensor functionalized with a cocaine-binding aptamer and a miniaturized electrochemical potentiostat. Our fluidics are driven by evaporation flow at physiological sweat rates (0.3-0.5 {micro}L/min/cm2). Our development lays critical groundwork towards wearable, continuous detection of illicit substances in sweat.