Development of poly(vinyl alcohol)/wood-derived biochar composites for use in pressure sensor applications

Carbon-based electrically conductive polymer composites have been considered as promising materials for piezoresistive pressure and strain sensors. The objective of this work is to investigate the behaviors of wood-derived biochar-filled polyvinyl alcohol (PVA) composites as pressure sensors. Composites of polyvinyl alcohol and wood-derived biochar were prepared by a solution casting method. The research found that with elevated pressure from 0 to 358 kPa, the electrical resistance of PVA/biochar composite sensors with 8, 10, and 12 wt% biochar content (to 10% PVA solution by weight) gradually decreased by 92, 98, and 99%, respectively. Also, the effects of sensor thickness (0.40, 0.50, and 0.60 mm) and temperature (from -20 to 70 degrees C) were investigated. Results indicated that effect of thickness was most influential in the 8 wt% PVA/biochar sensors. Higher temperature (40-70 degrees C) enhanced the sensor voltage output, while lower temperature (-5 to -20 degrees C) reduced the piezoresistive effects.