An E-skin for handwriting input at human-machine interface

Wearable human–machine interaction remains a huge challenge when various flexible electronics have been developed to date, for which the information input seems more difficult than the information output such as display devices. Here in this work, an e-skin for handwriting input was disclosed based on a double network hydrogel of gluten protein and polyvinyl alcohol (PVA) that is cross-linked by borax. The hydrogel can tightly adhere onto human skin, being stretchable, self-healable, and working properly even under breakage, which perfectly match the requirements of the e-skin for human–machine interaction. Under the assistant of deep learning, the handwriting of letter and words on it can be recognized with high accuracy of above 89%, even under tensile state or destruction. In addition, this flexible device is biocompatible and biodegradable benefiting from the protein and PVA networks, which make it suitable as a wearable e-skin and being free of electronic wastes. The finding of this work may open a window for the development of e-skin for the two-way human–machine interaction.