Piezoresistive strain sensor of conductive nickel@polyurethane sponge prepared by secondary coating based on double-layer crack structure

Abstract

Conductive sponge sensors based on crack structure have attracted widespread attention in the field of wearable electronics for their excellent compressibility. However, the conventional preparation methods such as primary-coating and single-layer crack structure tend to result in poor stability and sensitivity of conductive sponge sensors. Therefore, a high-performance sensor of conductive nickel@polyurethane sponge prepared by secondary coating based on the double-layer crack structure is proposed in this study. A uniform conductive Ni-layer was coated on polyurethane sponge by secondary-coating metal nickel via physical vapor deposition (PVD) and electroless deposition (ELD), and a double-layer crack structure was designed by using the cyclic compression method to construct cracks in the primary and secondary-coated Ni layers, respectively. The sensor exhibited excellent stability due to the secondary-coating method, and the double-layer crack structure improved the sensitivity of the sensor to detect small deformations (< 10%) (GF = 99.33), which was nearly 3.8 times higher than that of the secondary-coated conductive sponge sensor with single-layer crack structure. Meanwhile, the sensor possessed an ultra-wide sensing range, low resistance relaxation time, and fast response time of 122 ms, as well as excellent reproducibility, and showed excellent sensitivity and application potential of application detection in areas such as speech recognition, human motion monitoring, and physiological signal monitoring.

Graphical abstract