Processing Natural Wood into a High-Performance Flexible Pressure Sensor.

Flexible pressure sensors have received wide attention because of their potential applications in wearable electronics and electronic skins (e-skins). However, the high performance of the pressure sensors relies principally on the introduction of complex surface microstructures, which often involves either complicated procedures or costly microfabrication methods. Moreover, these devices predominantly use synthetic polymers as flexible substrates, which are generally nonbiodegradable or not ecofriendly. Here, we report a facile and scalable processing strategy to convert naturally rigid wood into reduced graphene oxide (rGO)-modified flexible wood (FW/rGO) via saw cutting, chemical treatment, and rGO coating, resulting in high-performance wood-based flexible piezoresistive pressure sensors. Benefiting from the largely deformable ribbon-like surface microstructures, the obtained wood-based pressure sensor displayed a high sensitivity of 1.85 kPa over a broad linear range up to 60 kPa and showed high stability over 10 000 cyclic pressings. The favorable sensing performance of the pressure sensor allows for accurate recognition of finger movements, acoustic vibrations, and real-time pulse waves. Moreover, a large-area pressure sensor array has been successfully assembled on one piece of flexible wood for spatial pressure mapping. The proposed strategy of directly using natural wood for high-performance flexible pressure sensors is simple, low-cost, sustainable, and scalable, opening up a new avenue for the development of next-generation wearable electronics and e-skins.