Multifunctional E‐Tattoos Based on Electrospun PVBVA Fibers Coated with Ti ₃ C ₂ T _x MXene for Energy Harvesting, Energy Storage, and Biometric Sensing

Abstract Multifunctional electronic tattoos (e‐tattoos) integrating energy harvesting, charge storage, and biosignal monitoring are critical for advancing wearable electronics. Most current technologies specialize in one or two functions, lacking a unified, skin‐compatible solution. A novel e‐tattoo is reported using electrospun poly(vinyl butyral‐co‐vinyl alcohol‐co‐vinyl acetate) (PVBVA) fibers coated with titanium carbide (Ti ₃ C ₂ T _x ) MXene. A single electrode triboelectric nanogenerator (TENG) was fabricated via a layer‐by‐layer method using a PVBVA/Ti ₃ C ₂ T _x /PVBVA (PMxP) sandwich structure, and achieved an open‐circuit voltage of 250 V, short‐circuit current of 2.9 µA, and power density of 250 mW m ^{− 2} (25 µW cm ^{− 2} ) under a 2 MΩ load, enabling triboelectric energy harvesting from human motion. A parallel‐plate capacitor using PVBVA/Ti ₃ C ₂ T _x electrodes and a PVBVA dielectric exhibited 14 pF capacitance at 10 kHz and 5 V, suitable for low‐power touch‐sensitive applications. Additionally, PMx‐based e‐tattoos captured real‐time electrocadiogram (ECG) and electromyography (EMG) signals with high skin conformability and minimal signal degradation. The device maintains mechanical flexibility, biocompatibility, and adhesion over extended wear. This scalable, non‐invasive platform demonstrates robust multifunctionality and durability, offering a promising route toward integrated, self‐powered wearable systems for health monitoring, human‐machine interfaces, and energy autonomy. The PMxP architecture represents a significant step toward all‐in‐one e‐tattoos that meet the demands of next‐generation electronics.