Ultrathin and Highly Conformal Self-Powered Sensors by Liquid-Phase Transferring.

Self-powered sensing technologies have sparked a revolution in electric devices. Furthermore, ultrathin characteristics are highly desirable for on-skin and wearable devices to achieve superior conformability on complex 3-dimensional surfaces, which facilitates improved wearing comfort and detection accuracy. However, developing self-powered sensors with ultrathin and conformal features without complicated fabrication processes remains a formidable challenge. Herein, we present an ultrathin self-powered sensor with high conformability, fabricated by a liquid-phase transferring approach. The sandwich-like sensor is spin-coated layer by layer on a water-soluble substrate. Upon immersion in water and complete dissolution of the sacrificial layer, the sensor can be transferred to a variety of surfaces with diverse morphologies. The ultrathin sensor shows long-term stability. When the 45-μm-thick sensor is transferred to human skin, robotic hands, insole, flat plates with fine bevels, cylinders, undulating surfaces, and leaf textures, the fingerprint and surface details of the objects are vividly reflected on the sensor surface, attesting to its exceptional conformability. Driven by the triboelectric effect, the self-powered sensor and its array exhibit good sensitivity and rapid response time, enabling tactile sensing functions for pressure, material species, surface roughness detection, and motion state. The proposed design strategies for ultrathin self-powered sensors hold immense promises in wearable devices, robotics, and human-machine interfacing.