Skin-actuated self-powered devices based on triboelectric nanogenerators (TENGs) have recently garnered increasing attention, as they can be used to develop electronic skins for healthcare, robotic intelligence, and human interface devices. TENGs typically require tribonegative materials to enable the top layers to either be in contact with or be insulated from other specific materials, resulting in suboptimal performance under practical conditions. Here, we describe the fabrication of a soft, transparent, flexible, stretchable, and skin-actuated TENG device using nanostructured polydimethylsiloxane with a silver nanowire transparent contact as a power source to activate commercial small electronic devices. The nanostructured TENG exhibited a high open-circuit voltage of ∼128 V upon contact with the human skin. This value was substantially higher than that of a TENG with no nanostructure (∼51.6 V), which was attributed to a higher effective contact area in the former. An ∼266 μW/ cm 2 power density could be achieved with the nanostructured TENG upon finger touch stimulation. The resulting electrical output power was then used to activate small commercial electronic devices such as light-emitting diodes. Additionally, due to its high transparency and signal response, the developed TENG was successfully implemented as a sensory platform to build a 3 × 3 keypad. The TENG devices were affixed to several objects to monitor daily activities and harvest biomechanical energy. Our findings suggest that the skin-stimulated elastomer-based TENG developed herein could open possibilities in the development of wearable sensors and power sources.

Ultrathin, breathable, and skin‐compatible epidermal electronics are attractive for wearable and implantable healthcare and biomedical applications. However, materializing and integrating all electronic components on ultrathin platforms is still challenging. Here, a charge‐storing electronic tattoo (E‐tattoo) device with ultrathin, breathable, and skin‐compatible properties is reported. Silk protein nanofibers (SNFs) and carbon nanotubes (CNTs) form the top and bottom electrodes that sandwich the intermediate dielectric layer fabricated using poly(vinyl alcohol) nanofibers. The E‐tattoo capacitors on the deformed skin, show excellent mechanical and electrical stability, and 60 µm‐thick capacitors exhibit frequency‐dependent capacitances (up to 350 pF at 5 kHz) and capability for memory operation. Mechanical bending induces capacitance change, which increases as the bending radius is decreased, indicating mechanical sensing capability of the E‐tattoo. SNF/CNT‐based triboelectric nanogenerator E‐tattoos can be connected to the capacitor E‐tattoo, and the charges generated by multiple bare‐finger touches can be stored in the capacitor (0.23 V for 200 touches). Due to the micro/nanopores in the NF networks, the device exhibits a water vapor transmission rate of 115.04 g m−2 d−1, which is better than that of a commercial band‐aid, as well as ethanol sensing capability. Developed E‐tattoo capacitor can be used for constructing multicomponent integrated ultrathin and epidermal electronics.

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