Chip-less Battery-less Wireless Electronic Skin by Single Crystalline Freestanding Membranes

Electronic skin (e-skin) has been developed to obtain a non-invasive human health monitoring electronic system with its imperceptibility. So far, one of the major shortcomings in this field is the bulky wireless communication system that severely affects its wearability. We introduce a single-crystalline non-Si-based e-skin system where fully conformable, ultrathin, piezoelectric, compound semiconductor membranes are incorporated as power-efficient wireless communication modules and extremely high sensitivity sensors without needing bulky chips and batteries. The developed GaN surface acoustic wave-based device successfully measured three different inputs wirelessly. The consistency and accuracy of the measured heart rate and pulse waveforms over a 7-day period strongly demonstrate the reusability and long-term wearability of our device. This study will change the paradigm of e-skins by providing versatile wireless platforms for fully imperceptible e-skins with very high sensitivity and low power consumption.