Electronically conductive hydrogel base on superhydrophobic and embedded micro-wrinkles for linear sensitivity in underwater monitors and tactile sensors.

Electronically conductive hydrogels are emerging as promising sensing materials, offering great potential for tactile sensors and wearable devices. However, interfacial diffusion tends to swell and disrupt conductive components of hydrogels in the harsh environment, thus achieving a flexible waterproof coating, stable conductive networks, and excellent sensing performance presents numerous challenges. Herein, we develop a superhydrophobic Vinyl-terminated polydimethylsiloxanes/multi-walled carbon nanotubes @Carbon black-hydrogel (Vi-PDMS/MWCNT@CB-hydrogel) that demonstrates exceptional water retention (>95%), anti-swelling property, and abrasion resistance performance, while maintaining the excellent superhydrophobicity and sensitivity. The cross-linked Vi-PDMS/Pentaerythritol tetra (3-mercaptopropionate) (PETMP) coating effectively hinders the diffusion of wrinkled MWCNT into the CB-hydrogel. The wrinkled Vi-PDMS/MWCNT coating is embedded into the CB-hydrogel surface, and served as the active origin of sensing signals, while synergistically improves the linear sensitivity (Gauge Factor (GF) = 8.36) and environmental stability. Furthermore, the wrinkled coating was embedded into the inclined conical microarray of CB-hydrogel, enabling the spatial response singles of the sensor, and demonstrating a linear response sensitivity (S = 21.41 kPa-1). The array sensor converts physical properties of objects such as texture, hardness, shape, and weight into electrical signals, thereby facilitating tactile recognition. The proposed fabrication strategy and microarray design provide a versatile platform for tuning the flexible sensor performance across different applications and offer new opportunities for the development of smart hydrogel-based sensors.