Smart Wearable, Highly Sensitive Pressure Sensor with MWNTs/PPy Aerogel Composite

Abstract

The fabrication of highly sensitive, low-cost pressure sensors with reliable detection performance has received plenty of attention as there is an urgent need for body movement detection and monitoring devices in different fields. The MWNTs/PPy AG composite based piezo-resistive pressure sensor was fabricated using two coating processes. The first coating was with multi-walled carbon nanotubes (MWNTs) and the second was poly-pyrrole (PPy) coating with in situ polymerization performed on commercially available aerogel (AG) as the substrate. The poly-dopamine (PDA) coating was applied as a substrate surface modification method to investigate its effect to enhance the conductivity, sensitivity and other performance aspects of MWNTs AG, PPy AG and MWNTs/PPy AG. An anionic surfactant, sodium dodecyl benzene sulfonate (SDBS) was used as the dispersing agent to prepare a homogeneously mixed MWNTs aqueous solution, which was then used as a scouring agent to remove an existed surface coating on the AG. The retained SDBS in the MWNTs AG worked as a dopant with pyrrole in situ polymerization to improve the conductivity. MWNTs/PPy AG pressure sensor shows high sensitivity (34.64 kPa−1 with 1 kPa), acceptable conductivity and good stability over 5000 continues pressure cycles in the 0.45–4 kPa pressure range. Lowest detection level of MWNTs/PPy AG was close to 0.2 kPa. The MWNTs/PPy AG composite shows promising performance in detecting human body movements in the medium pressure range, which is generally used for health care, rehabilitation and aesthetic purpose.