Smart paper from graphene coated cellulose for high-performance humidity and piezoresistive force sensor

Highly sensitive and fast-responding humidity and piezoresistive sensor was fabricated based on cellulose paper coated with graphene (CGN), which were synthesized via dip-coating (D-CGN) and vacuum filtration method (V-CGN). CGN showed excellent electrical properties and SEM images confirmed that graphene nanoplatelets were held tightly between the pores of the paper. V-CGN based sensor displayed excellent sensitivity and fast response to the humidity change at room temperature. The highest response of 75 % and 290 % was achieved for D-CGN and V-CGN based sensor, respectively. In addition, both the sensors exhibited fast response and recovery along with excellent repeatability characteristics. Besides, both the sensors displayed excellent piezoresistive performance. The highest piezoresistive response of 125 % and 250 % for D-CGN and V-CGN was achieved. Cellulose paper with low cost, lightweight and biocompatibility combined with graphene could be a promising material for smart, wearable electronic devices.