Multifunctional and Ultrathin Electronic Tattoo for On‐Skin Diagnostic and Therapeutic Applications

Abstract Epidermal electronic systems for detecting electrophysiological signals, sensing, therapy, and drug delivery are at the frontier in man–machine interfacing for healthcare. However, it is still a challenge to develop multifunctional bioapplications with minimal invasiveness, biocompatibility, and stable electrical performance under various mechanical deformations of biological tissues. In this study, a natural silk protein with carbon nanotubes (CNTs) is utilized to realize an epidermal electronic tattoo (E‐tattoo) system for multifunctional applications that address these challenging issues through dispersing highly conductive CNTs onto the biocompatible silk nanofibrous networks with porous nature to construct skin‐adhesive ultrathin electronic patches. Individual components that incorporate electrically and optically active heaters, a temperature sensor (temperature coefficient of resistance of 5.2 × 10⁻³ °C⁻¹), a stimulator for drug delivery (>500 µm penetration depth in skin), and real‐time electrophysiological signal detectors are described. This strategy of E‐tattoos integrated onto human skin can open a new route to a next‐generation electronic platform for wearable and epidermal bioapplications.