Multifunctional, superelastic, and environmentally stable sodium alginate/mxene/polydimethylsiloxane aerogels for piezoresistive sensor

Aerogel sensors have drawn considerable interest in the recent research world. However, simultaneously maintaining superelasticity and an outstanding piezoresistive effect under changing environmental conditions remains challenging. Here, sodium alginate (SA) was used as a bonding agent for MXene nanosheets and polydimethylsiloxane (PDMS) as a reinforcing agent to prepare SA/MXene/PDMS (SMP) composite aerogel with excellent high conductivity, mechanical elasticity, reliable thermal insulation, and good hydrophobicity. The interaction between MXene nanosheets and SA enhances the 3D network framework of the aerogel. The aerogel with a layer-support network structure prepared by the modified directional freezing method showed light weight, high sensitivity (37.43 kPa−1), significant reversible compression (70%) and excellent fatigue resistance (60,000 cycles). The piezoresistive sensor based on SMP composite aerogel can quickly respond to pressure/strain signals, which can be further used for pulse beating, sound detection, motion monitoring, foot posture diagnosis and human health monitoring. Additionally, the MXene aerogel sensor based on carbon material with frequency response characteristics can detect low to high frequency vibration signals, has frequency response characteristics that can detect low to high-frequency vibration signals, making it useful for rotating machinery speed detection, cantilever beam vibration detection, non-destructive testing of cantilever beams, and other engineering applications. With its the layered porous structure and the assistance of PDMS, the aerogel also exhibits larger water contact angles (119°) and extreme environmental suitability (−40 to 80 °C), performing a wide range of application potential in many fields.