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.

Keywords: Artificial thermoreceptors; Sensors; Thermoelectric composites; Wearable electronics.

Fig. 1

Concept of a robotic arm with an artificial thermoelectric nociceptive system and performance of the as-prepared composite samples. A Left: Working principle of the robot featuring an artificial thermoelectric nociceptive system. Right: Structure of a biological nociceptive sensory system. This thermoelectric nociceptive system closely mirrors biological pain perception mechanisms. B Schematic diagram of p–n integrated thermoelectrics using UV-induced patterning with origami techniques. C Reaction Schematic Diagram of photobase generator after UV exposure. D Thermoelectric performance with the increase in photobase generator concentration. E Thermoelectric performance over varying exposure times in air

Fig. 2

Performance of thermoelectric devices. A Open-circuit voltages as a function of temperature differences of π-type thermoelectric device and p–n integrated thermoelectric device; inset: Schematic illustration of 10 p–n paired π-type thermoelectric device and 10 p–n paired p–n integrated thermoelectric device. B Temporal voltage variation with a temperature difference cycle ranging from 0 and 60 K. C Temporal voltage variation of the thermoelectric device with temperature differences at 20, 40, and 60 K. D Map of the spatial variation test. E Spatial variation of thermoelectric device voltage with temperature differences at 20, 40, and 60 K

Fig. 3

Nociceptive behaviors of artificial thermoreceptor. A Threshold behavior: output voltage of the thermoreceptor in response to increasing temperatures. B Threshold response to both hot and cold stimuli. C No adaptation: output voltage response over repeated pulse duration. D Relaxation: relaxation times across different temperature differences. E Allodynia hyperalgesia: characteristic responses to normal (no injury, 10 p–n pair of thermoelectric materials) and abnormal (low injury, 20 p–n pair of thermoelectric materials and strong injury, 30 p–n pair of thermoelectric materials) conditions. F Hyperalgesia: characteristic responses to both normal (no injury) and abnormal (low injury and strong injury) conditions

Fig. 4

Device structure and mechanism of the biomimetic thermo-nociceptive robotic arm. A Schematic of the functional mechanism of a biological nociceptor. B Flow diagram detailing the functional mechanism of the artificial thermoreceptor. C Device structure of the robotic arm. Pain response of the robotic arm to external thermal stimuli from D a human finger (− 309 K), E hot water (− 363 K), and F an ice block (− 273 K). Scale bar: 5 cm

Fig. 5

Thermo-nociceptive protective response behavior of the biomimetic thermo-nociceptive robotic arm. A Voltage variation over time in response to different pain levels, presented experimentally and with Hyperbl fit. B Photographs and infrared images of the robotic arm’s pain response to different thermal stimuli. Scale bar: 2 cm. C Hyperbl fitted and experimental data on the response time of the artificial thermoreceptor at different pain levels. D Response time of the robotic arm under varying temperatures. E Confusion matrix displaying classification accuracy of pain levels by analyzing thermal stimuli and response time