Stable epidermal electronic device with strain isolation induced by in situ Joule heating

Epidermal electronics play increasingly important roles in human-machine interfaces. However, their efficient fabrication while maintaining device stability and reliability remains an unresolved challenge. Here, a facile in situ Joule heating method is proposed for fabricating stable epidermal electronics on a polyvinyl alcohol (PVA) substrate. Benefitting from the precise control of heating locations, the crystallization and enhanced rigidity of PVA are restricted to desired areas, leading to strain isolation of the active regions. As a result, the electronic device can be conformably attached to skin while showing negligible degradation in device performance during deformation. Based on this method, a flexible surface electromyography (sEMG) sensor with outstanding stability and highly comfortable wearability is demonstrated, showing high accuracy (91.83%) for human hand gesture recognition. These results imply that the fabrication method proposed in this research is a facile and reliable approach for the fabrication of epidermal electronics.