High-Reliability Thermoreceptors with Minimal Temporal and Spatial Variations Through Photo-Induced Patterning Thermoelectrics

Abstract

The development of bionic sensing devices with advanced physiological functionalities has attracted significant attention in flexible electronics. In this study, we innovatively develop an air-stable photo-induced n-type dopant and a sophisticated photo-induced patterning technology to construct high-resolution joint-free p–n integrated thermoelectric devices. The exceptional stability of the photo-induced n-type dopant, combined with our meticulously engineered joint-free device architecture, results in extremely low temporal and spatial variations. These minimized variations, coupled with superior linearity, position our devices as viable candidates for artificial thermoreceptors capable of sensing external thermal noxious stimuli. By integrating them into a robotic arm with a pain perception system, we demonstrate accurate pain responses to external thermal stimuli. The system accurately discerns pain levels and initiates appropriate protective actions across varying intensities. Our findings present a novel strategy for constructing high-resolution thermoelectric sensing devices toward precise biomimetic thermoreceptors.

1. Introduction

The rapid development of bionic intelligent sensing technology, combined with the continuous advancement of information technology such as artificial intelligence and big data, has facilitated important advancements in functional materials, flexible electronics, and humanoid robotics [1–7]. These developments are driven by interest in bionic sensors, which can be classified into visual, auditory, and tactile types based on their unique structures and working mechanisms [8–12]. Each type is tailored to adapt to specific functions within different scenarios [13–18]. However, more sophisticated physiological functions, such as the human-like injury responses, remain underdeveloped [19]. For instance, when individuals are exposed to noxious stimuli from the external environment, a series of complex physiological responses are triggered. These responses include a sense of pain, visible signs of injury, and healing processes, all designed to protect the individual from harm or further damage. Consequently, there is significant interest and demand for advanced electronics that integrate perception capabilities.

Pain perception is central to the body’s physiological protection mechanisms. The detection of physical pain is achieved through nociceptors, a type of sensory receptor that encodes noxious stimuli into neural signals and sends “possible danger” signals to the spinal cord and brain. This triggers various physiological and behavioral responses [20, 21]. A biological nociceptor is characterized by five distinct features: (i) a “threshold” to trigger pain; (ii) “no adaptation,” meaning it continues to trigger in reaction to recurrent noxious stimuli; (iii) “relaxation” after the noxious stimuli have ceased; and abnormal sensitization, known as (iv) “allodynia” and (v) “hyperalgesia,” while the injury remains. Nociceptors are primarily divided into mechanonociceptors, visual nociceptors, chemical nociceptors, and thermoreceptors [22–25]. Among them, thermoreceptors exhibit bimodal functionality, integrating both thermal sensing and nociceptor function through shared mechanism. Although previous studies have reported on the mechanonociceptive, visual, and chemical nociceptive behaviors of semiconductor devices, including complementary metal oxide semiconductors, transistors, and resistive access memories, thermo-nociceptive system are still in their early stages of development [26–30]. Thus, the pursuit of appropriate functional materials to facilitate the design of optimal thermoreceptors is imperative to address the current void in nociceptor classification.

Flexible thermoelectric devices show great potential for transforming the field of bionic sensing devices [31–38]. These devices not only capitalize on the inherent benefits of thermoelectric materials but also introduce new levels of conformability and mechanical robustness, which exhibit remarkable advantages when serving as artificial thermoreceptors (Note S1). First, their sensing mechanism closely aligns with the biological pain perception mechanism, where both biological nociceptors and thermoelectric-based artificial thermoreceptors activate protective mechanisms by converting harmful external thermal stimuli into electrical signals. Secondly, these devices offer high sensitivity and fast response, essential for real-time pain detection. Moreover, their flexibility allows seamless integration into wearable systems and robotic platforms, enabling biomimetic functionalities that were previously unattainable. The development of such devices addresses the critical need for advanced artificial thermoreceptors that can mimic the complex pain perception and response mechanisms of biological systems.