Developing a Flexible Electrochemical Sensor for Trace Detection of Energetic Materials

Manually inspecting packages which may contain explosives presents inherent hazards from unplanned detonation. We are developing a sensor for remote explosives detection using a 3,4-propylenedioxythiophene (ProDOT)-based copolymer channel organic electrochemical transistor (OECT). Specifically, we describe the OECT behavior using a range of electrolyte ionic strengths especially at highly dilute (< 1 mM) ionic strengths. The ProDOT channel provides an example of accumulation mode sensing, benchmarked against standard poly(3,4-ethylene dioxythiophene) doped with poly(styrene sulfonate) (PEDOT:PSS) based OECT sensors. Additionally, a functionalized polyethylene-glycol dimethacrylate molecularly imprinted polymer (MIP) barrier is placed atop the channel to serve as a selective layer. Minimizing false positives, the additional layer produces a species selective barrier; this directly impacts OECT dynamics allowing us to precisely isolate the polymer morphology in species transport. This sensor will describe OECT versatility in both depletion and accumulation mode operation, while holistically characterizing electrolyte concentration effects on transport roles in sensor functionality.