Electrically conductive and highly compressible anisotropic MXene-wood sponges for multifunctional and integrated wearable devices

Abstract

Although piezoresistive sensors have wide applications in human motion detection and wearable electronics, it is still a challenge to produce multifunctional and integrated sensors with wide working ranges and linear sensing responses. Herein, electrically conductive, highly compressible, and structurally anisotropic MXene-wood (MW) sponges are fabricated by converting balsa wood blocks to compressible wood sponges with extremely low density and highly anisotropic porous structure, followed by decorating with conductive MXene sheets. The MW sponge is utilized to assemble a piezoresistive sensor with a large working range of 0-25 kPa, wide linear sensing ranges of 5%-50% and 0-180o, and excellent long-term reliability under a bending angle of 30° for 5000 cycles. Additionally, the sensor is suitable for monitoring practical human physiological signals including pulse beating, and finger and wrist bending. An all-MW sponge-based multifunctional and integrated sensing system is constructed by integrating the MW sponge piezoresistive sensor, the MW sponge-based solid-state supercapacitor, and the MW sponge electrophysiological electrodes. The sensing system can concurrently detect surface electromyogram and tactile pressures, and hence realize real-time closed-loop controls. The multifunctional and integrated MW sponge sensing system would have great potentials in real-time pressure recognition and human-machine interfaces.