Large-Area 2D Metasurface-Based Triboelectric E-Skin Arrays: Contact & Proximity Tactile Mapping with Broadband...

Recent advances in electromechanically coupled, self-powered, flexible transducer-enabled electronic skins are predominantly driven by the capacitive triboelectric nanogenerators (TENGs), which operate intrinsically as multifunctional sensor-cum-energy harvester. The resulting TENG's operability in cutting-edge wearable technologies can be significantly augmented by introducing 2D dielectric metasurfaces, which optimize functionality through enhanced electromechanical coupling. Here, we introduce a 2D metasurface-TENG e-skin that unifies tactile (contact and inductive) and acoustic sensing in a single ultrathin platform. Large-area nanocone (NC) metasurfaces are engineered on 100 µm polydimethoxysilane (PDMS) films via laser-interference lithography (LIL) and soft molding, which boosts triboelectric charge density and provides optical diffraction cues for strain monitoring. Integrated into a 3 × 3 array, the device delivers real-time tactile pressure imaging with low crosstalk and non-contact proximity detection. The NC-TENG patch also functions as a self-powered acoustic sensor, in which the sound pressure level (SPL) and frequency response are quantified in both spatial and spectral domains over a broad frequency range (∼50-6400 Hz). Compared to pristine PDMS, the metasurface enhances open-circuit voltage by ≈46% under identical loading and sustains stable electrical output. By coupling electromechanical and electro-acoustic transductions with metasurface optics, this work advances multimodal, arrayed e-skins for next-generation human-machine interfaces and wearable sensing.