Carbon Black/Graphene Nanosheet Composites for Three-Dimensional Flexible Piezoresistive Sensors

Recently, more and more conductive nanocomposites are used to enhance the sensing characteristic of flexible sensors. However, the influence of the composite structure of nanocomposites on the performance of the sensor is rarely investigated. Herein, two composite structures of carbon black (CB)/graphene nanosheets (GNs) are used for three-dimensional flexible piezoresistive sensors. Based on the composite structures of CB and GNs, three flexible piezoresistive sensors with the nanocomposites of CB and GNs are fabricated. Experimental results show that different composite structures of CB and GNs result in several times differences in sensitivity and gauge factor. Among three samples, the sensor with the composite structure (first coating GNs and then filling CB in the SEBS substrate surface) exhibits the highest sensitivity of 197.56 kPa–1 (below 300 Pa) and gauge factor (GF) of 47.60. Meanwhile, the sensor shows a fast response of 120 ms, instant recovery of 63 ms, and excellent stability (>2000 cycles). In addition, the sensor's potential applications in monitoring speaking and gesturing are demonstrated. This work provides a strategy to obtain a highly sensitive piezoresistive sensor with conductive nanocomposites.