Flexible planar concentric circular micro-supercapacitor arrays for wearable gas sensing application

Micro-supercapacitor (MSC) are considered to be a promising candidate for wearable energy storage due to their scale down in dimensions to fit on-chip geometries of integrated nanosystem, high charge/discharge efficiency, long lifetimes and strong security compared to Li-ion batteries. In this work, we present a polypyrrole (Ppy) film based MSC arrays by combining photolithograph and electrodepositon method. The designed MSC with concentric circles structure exhibited a large areal capacitance of 47.42 mF/cm² and provided a power density of 0.185 mW/cm² at an area energy density of 0.004 mWh/cm². MSC arrays connected in series were utilized as power source to drive a wearable gas sensor on the same flexible substrate. As-designed wearable self-driven room temperature ethanol gas sensor showed a quick response time (13 s) and recovery time (4.5 s), good selectivity to ethanol and a high detection capability of less than 1 ppm at room temperature, proving the feasibility of the wearable MSC arrays integrated gas sensing system and offering a quick, easy and comfortable way for personalized monitoring drunken driving.