Pit organ-inspired composite eutectogel electronic skin with integrated light-thermal-electric conversion for touchless multimodal human-computer interaction

Thermoelectric generator-based electronic skins (e-skins) have attracted considerable attention due to the effective utilization of low-grade heat. However, their working mode, based on thermal conduction, fundamentally limits non-contact and long-distance sensing capabilities. Herein, inspired by the infrared vision mechanisms of pit vipers, a unilateral-apertured multi-element array e-skin (UMES) with a pit structure analogous to the pit organ is developed based on light-thermal-electric (LTE) conversion composite eutectogel (LTEG) with high stretchability (2585 %), toughness (10.08 MJ m⁻³), and self-adhesion (156.32 kPa). The LTEG is composed of polymer chains with hydrogen-bond clusters, imidazole-triazine-ring porous polymer particles (ITPP), and iron-based redox pairs. These components synergistically form composite networks via hydrogen bonds and coordination bonds between ITPP and polymer chains, as well as coordination interactions of iron ions with the polymer matrix. Using the Fe³⁺/Fe²⁺ redox couple, a Seebeck coefficient of −2.06 mV K⁻¹ is achieved. The ITPP serve as photothermal units, emulating the thermosensitive cells of pit organs through photothermal conversion. Their intrinsic compatibility with the gel matrix eliminates the need for layered designs, thereby achieving integrated LTE conversion via a composite strategy. The unilateral-apertured structure of the UMES spatially confines infrared light to a predefined electrode region through perforated regions while shielding adjacent zones with opaque barriers, explicitly defining device polarity and eliminating reverse voltage interference. Consequently, the UMES is designed for touchless multimodal human-computer interactions (HCI), ranging from letter output on a smartphone to deep-learning-assisted remote control of drones. This work holds immense promise for next-generation self-powered e-skins in HCI.