The central processes driving biological phenomena are based on the conduction of ions and electrons in biomaterials, implying the possibility of achieving a fully biomaterial-based electronic skin. However, finding the appropriate biomaterials for electronic skins is still challenging. Here, a photoresponsive, self-healable, and biomaterial-based optoelectronic skin (OE-skin) fabricated with melanin nanoparticles and silk protein is proposed and the electronic properties and their mechanisms in the artificially generated OE-skin are reported. Not only does silk protein hydrogel provide a transparent and skin-compatible platform for use as OE-skin but it also provides the appropriate environment for melanin to demonstrate high electrical conductivity. The OE-skin can be considered a p-type semiconducting material showing high conductivity of up to 6 mS cm−1 in addition to a 40% enhancement in the conductivity by green laser and ultraviolet light emitting diode illuminations. Additionally, the OE-skin autonomously heals itself from multiple cuts, allowing the restoration of its electrical properties. These material properties enable applications for strain-sensors, humidity sensors, and ultraviolet light sensors, as well as image pixels to convert light-lettering into electrical signals. The proposed fully biomaterial-based OE material platform offers a new way for next-generation electronic skins to achieve a seamless interface with the human body.
A.W. and N.G. contributed equally to this work. The authors acknowledge the support from the National Research Foundation (NRF) of Korea (Nos. 2019R1A2C2088615 and 2021R1A4A5032470) and Rural Development Administration (PJ016130, Research Program for Agricultural Science & Technology Development of the National Academy of Agricultural Science).
