Wearable piezoresistive sensors have aroused considerable attention for their huge potential in emerging applications such as healthcare monitoring and intelligent electronics. However, the fabrication of piezoresistive sensors that combine excellent sensing performance with outstanding working reliability in watery environments still remains challenging. Herein, a superhydrophobic polyurethane (PU) sponge was proposed as a piezoresistive sensor through the synthesis of d-asparagine-modified MXene nanosheets (MXene-NH2) and coating of a conductive cross-linkable layer constructed by dihydroxyl-terminated poly(dimethylsiloxane) (PDMS(OH)) and MXene-NH2 nanosheets. The microscale sponge skeleton and nanoscale PDMS-MXene nanosheet wrinkles formed a hierarchically rough structure in support of superhydrophobicity with a water contact angle of 160 degrees. Benefiting from the chemically cross-linkable network and strong adhesion of PDMS-MXene nanosheet coating, the obtained PDMS-MXene@PU sponge exhibited a robust water repellency with water contact angles (WCAs) larger than 150 degrees after enduring chemical and physical damages. Owing to the synergistic effect of the production of microcrack junctions in the PDMS-MXene nanosheet layer and contact separation between conductive backbones, the PDMS-MXene@PU sensor was successfully applied in monitoring full-scale human motions (e.g., blowing, facial expression, finger and knee bending, etc.) with excellent sensing performances of the gauge factor reaching -1.9. The findings conceivably stand out as a methodology to fabricate robust superhydrophobic piezoresistive sensors with desirable sensing property for innovative and broad applications even under special working conditions.

Facile fabrication of functional superhydrophobic porous materials with full biodegradability for efficient removal of oily pollutants from water has been of considerable interest for its great significance in environmental protection. Herein, a fully organic and biodegradable superhydrophobic sponge is fabricated with carnauba wax (CW) via dip-coating, nonsolvent induced phase separation and spraying processes on a freeze-dried pomelo peel. The as-fabricated sponge was covered with flower-shaped patterns aggregated by CW nanosheets, and presented great water repellency with a contact angle of 154 degrees. Thanks to the 3D porous architecture and superhydrophobicity/superoleophilicity, the sponge exhibited great oil absorptive capacity, oil selectivity, separation efficiency and reusability for immiscible oil/water mixtures. Interestingly, the multi-layer compressed sponges realized gravity-driven surfactant-stabilized water-in-oil emulsion separation with high permeation flux of up to 5729 L.m- 2.h- 1 and excellent efficiency of oil purity larger than 99.9%. Importantly, the superhydrophobic sponge was derived from cheap renewable natural resources, and capable of being completely biodegraded after discarding. The findings conceivably stand out as a new tool to fabricate superhydrophobic materials with sustainability and biodegradability for oil accidents and industrial sewage emissions.