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

[Display omitted] •A reinforced MXene aerogel was constructed by molecular engineering and structural engineering. At the molecular scale, the polymer sodium alginate was used to promote the cross-linking of MXene nanosheets, and at the mesoscopic scale, the laminated structure was obtained by the double temperature gradient directional casting method. While polydimethylsiloxane (PDMS) was used for external curing.•The hybrid SA/Mxene/PDMS (SMP) aerogel shows extraordinary comprehensive properties, including lightweight (0.05 g/cm3), compressive resilience under large deformations (Strain = 70%), wide operating pressure range (50 K), promising pressure sensitivity (37.43 kPa−1), surprising strain GF values (435), and excellent fatigue resistance (60,000 cycles under 100 Hz)•The SMP aerogel sensors have a wide range of applications, which can be used in the field of engineering to detect the vibration of engineering structures. The SMP aerogel sensors could also be used in human health monitoring. In addition, The SMP aerogels have excellent hydrophobic properties (water contact angle 119°) and obvious thermal insulation properties, which can be used for high and low temperature operation (−40 to 80 °C). It has a wide applicable future. 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