Flexible hydrogel triboelectric nanogenerator-based smart wristband for handwriting recognition with the assistance of deep learning

Wearable electronic devices are required to overcome the traditional limitations of rigidity and unsustainable power sources, thereby endowing complex electronics with advantageous characteristics such as stability, high output, and flexibility. Flexible triboelectric nanogenerators (TENGs) based on hydrogels have been demonstrated as stable and sustainable wearable power sources and self-powered sensing devices, achieving significant progress in human-machine interaction, handwriting recognition, and medical monitoring. In this work, a conductive hydrogel (PHK hydrogel) doped with boric acid and KCl was developed as a strain sensor, exhibiting high stretchability (1520%), high sensitivity (GF=1.58), and rapid response (0.35   s). A triboelectric nanogenerator (PHK TENG) based on the PHK hydrogel was assembled, demonstrating dual functionality of energy harvesting and pressure sensing. Furthermore, a four-channel smart wristband incorporating PHK TENG was designed, showcasing exceptional performance in handwritten text monitoring. With the assistance of deep learning technology, the PHK TENG based smart wristband achieved effective recognition of Arabic numerals with an accuracy of 98.21%. The results indicated that this work excels in wearable comfort and functionality, demonstrating significant potential in the field of intelligent wearable sensing and contributing to steering human life toward a more convenient and intelligent future.