Wearable multi-sensing double-chain thermoelectric generator

Wearable electronics play a crucial role in advancing the rapid development of artificial intelligence, and as an attractive future vision, all-in-one wearable microsystems integrating powering, sensing, actuating and other functional components on a single chip have become an appealing tendency. Herein, we propose a wearable thermoelectric generator (ThEG) with a novel double-chain configuration to simultaneously realize sustainable energy harvesting and multi-functional sensing. In contrast to traditional single-chain ThEGs with the sole function of thermal energy harvesting, each individual chain of the developed double-chain thermoelectric generator (DC-ThEG) can be utilized to scavenge heat energy, and moreover, the combination of the two chains can be employed as functional sensing electrodes at the same time. The mature mass-fabrication technology of screen printing was successfully introduced to print n-type and p-type thermoelectric inks atop a polymeric substrate to form thermocouples to construct two independent chains, which makes this DC-ThEG flexible, high-performance and cost-efficient. The emerging material of silk fibroin was employed to cover the gap of the fabricated two chains to serve as a functional layer for sensing the existence of liquid water molecules in the air and the temperature. The powering and sensing functions of the developed DC-ThEG and their interactions were systematically studied via experimental measurements, which proved the DC-ThEG to be a robust multi-functional power source with a 151mV open-circuit voltage. In addition, it was successfully demonstrated that this DC-ThEG can convert heat energy to achieve a 3.3V output, matching common power demands of wearable electronics, and harvest biothermal energy to drive commercial electronics (i.e., a calculator). The integration approach of powering and multi-functional sensing based on this new double-chain configuration might open a new chapter in advanced thermoelectric generators, especially in the applications of all-in-one self-powered microsystems. Flexible electronics: energy harvesting and sensingA wearable thermoelectric device enables energy generation and sensing for health monitoring. Flexible electronic devices are promising candidates for personal health monitoring, and the ideal device would combine multiple functions in a single device. Two of the most important of these functions are energy generation and sensing. In this paper a team from University of Electronic Science and Technology of China led by Xiao-Sheng Zhang reports a thermoelectric-based device that combines these functions. Based on screen printing technology, they prepare n-type and p-type inorganic films onto a flexible polymer substrate, with their device being able to generate a voltage of up to 151mV driven by a thermoelectric effect. The water sensitivity and temperature sensitivity of silk fibroin contained in the device enables moisture and temperature to be sensed.