A biocompatible triboelectric nanogenerator-based edible electronic skin for morse code transmitters and smart healthcare applications

Skin-inspired electronic devices have gained immense interest due to their application in prosthetics, healthcare, robotics, and humanmachine interactions. Mimicking human skin and incorporating multifunctional properties such as stretchability, flexibility, biocompatibility, biodegradability, and paving the way for self-powered electronic skin (e-skin) is highly desirable. The present work reports the fabrication of biocompatible triboelectric nanogenerator (TENG)-based edible electronic skins made of a biocompatible chitosan film. The fabricated chitosan film was engineered using plasticizers to enhance its flexibility and mechanical strength. To make the entire device biocompatible, edible gold leaf, which is used as a decorative layer in the sweets of the Indian subcontinent, has been used as an electrode. Both the chitosan film and the edible gold electrode were studied for their biocompatibility by immersion in acetic acid and H2O2, where the films were completely dissolved in 1 h and 50 h, respectively. The e-skins were used as the active layer in the triboelectric nanogenerator by working under both vertical contact separation and single electrode modes of triboelectrification. Furthermore, the fabricated device has been used for real-time applications in self-powered sleep monitoring systems as well as for wearable Morse code transmitters. The electrical response and performance in real-time applications prove that the developed e-skin-based device is a promising candidate for future wearable applications in health care, humanmachine interactions and haptics.