Multifunctional polyether block amides/carbon nanostructures piezoresistive foams with largely linear range, enhanced and humidity-regulated microwave shielding

Flexible foam sensors have great potential applications in wearable electronic skin and motion detection. However, they usually have a low linear range, complex and no environment-friendly preparation process. Meanwhile, the obtaining of highly porous foam sensors also faces challenge via supercritical foaming. Herein, a novel, environment-friendly and easily scaled-up batch melt foaming technology was utilized to fabricate flexible, highly porous and multifunctional polyether block amides (PEBA)/carbon nanostructures (CNS) composite foams. The foams showed good piezoresistive performance with largely linear range as well as enhanced and humidity-regulated electromagnetic interference (EMI) shielding. PEBA/CNS composites were foamed successfully above the melt temperature of PEBA, and the foamed PEBA/CNS composite exhibited refined cell morphology and broadened foaming window. The highly porous (0.76) PEBA/CNS composite foams had a largely linear range up to 70 % compression strain with a gauge factor (GF) of 1.24, which also exhibited durable, highly invertible and reproducible piezoresistive behavior. Meanwhile, the PEBA/CNS composite foams were capable of monitoring human motions as wearable sensors. In addition, the specific EMI SE of PEBA/CNS composite foams was sharply increased. Furthermore, EMI shielding of PEBA/CNS composite foams could be adjusted between inefficient shielding (<20 dB) and effective shielding (>20 dB) with the change of humidity. Such foams had a great prospect in monitoring human motions while also protecting health from electromagnetic waves as a wearable device.