Anti-Freezing Wearable Tactile Sensors Prepared by Laser Processing of Crumpled Xanthan Gum-Based Hydrogels

Wearable piezoresistive tactile sensors are becoming increasingly popular in fields related to human motion/health monitoring, and artificial intelligence. However, piezoresistive materials are still limited in terms of safety and biocompatibility in medical settings, as well as availability under harsh conditions. Herein, elastic and biocompatible hydrogels are prepared by cross-linking of xanthan gum, polyvinyl alcohol, carbon nanotubes, and glycerol. The presence of glycerol results in hydrogel exhibiting an outstanding freezing resistance (−40 °C). Meanwhile, the controllable, large-scale, and facile two-step direct laser writing process allows the fabrication of hydrogels with double-rough surface structures. By tuning surface roughness, the sensors with the resulting hydrogels show a wide detection range with high sensitivities of 27.5, 5.4, and 2.1 kPa −1 under pressures of 0.1–6, 6–25, and 25–80 kPa. The sensors also display fast response time (≈126 ms), low detection limit (2.26 Pa), good reproducibility of sensing performance (1000 cycles), relevant freezing tolerance (−40 °C), and decent environmental stability (over 30 days). This work provides a low-cost, ease of manipulation, high reproducible, and large-scale way for the microstructure engineering of natural-polymer hydrogels and promotes their widespread applications.