Environmentally Friendly and Biodegradable Ultrasensitive Piezoresistive Sensors for Wearable Electronics Applications

Highly sensitive, flexible sensors that can be manufactured with minimum environmental footprint and be seamlessly integrated into wearable devices are required for real-time tracking of complex human movement, gestures, and health conditions. This study reports on how biodegradation can be used to enhance the sensitivity and electromechanical performance of piezoresistive sensors. Poly(glycerol sebacate) (PGS) elastomeric porous sensor was synthesized and blended with multiwall carbon nanotubes (MWCNTs) and sodium chloride (NaCl). Because of their unique porous characteristics, a single linear behavior over a large range of pressures (<= 8 kPa) and an increase in their sensitivity from 0.12 +/- 0.03 kPa(-1) up to 8.00 +/- 0.20 kPa(-1) was achieved after 8 weeks in a simulated body fluid media. They can detect very low pressures (100 Pa), with negligible hysteresis, reliability, long lifetime (>200 000 cycles), short response time (<= 20 ms), and high force sensitivity (<= 4 mN). The characteristics of the developed foam sensors match the sensing characteristics of the human finger to pave the way toward low-footprint wearable devices for applications including human movement and condition monitoring, recreation, health and wellness, virtual reality, and tissue engineering.