Self-powered tactile sensor for real-time recognition of Morse code based on machine learning

Developing lightweight, green, and flexible wearable electronics with high sensitivity and multifunctional sensing capabilities is of important significance in the field of outdoor sports, such as mountaineering, animal tracking and protection. This work proposes a silk fibroin fibers-based triboelectric nanogenerator (SF-TENG) to harvest tiny energy from human fingertip tapping and act as a self-powered tactile sensor. The SF-TENG adopts a green, efficient, and low-cost fabrication strategy, in which a breathable and electropositive silk fibroin fiber membrane and a silver conductive layer are prepared by electrostatic spinning and magnetron sputtering, and combined with a conductive cloth and a breathable tape to form a flexible sensor that can be attached to a human skin. The thin and soft portable TENG device, having a thickness of only 0.3 mm and a mass of 354 mg at the dimension of 4.5 cm × 4.5 cm, can generate a maximum power density of 1.0 W m^-2. Furthermore, the SF-TENG has excellent sensitivity of 1.767 mV Pa^-1 with good cyclic stability. The superior sensing characteristics provide new avenues for Morse code applications toward outdoor wearable autonomous communication. The proposed SF-TENG offers promising solutions in multi-scenario outdoor sport, human-machine interface interaction, and security systems.