Ultrasensitive Flexible Thermal Sensor Arrays based on High‐Thermopower Ionic Thermoelectric Hydrogel

Abstract

Ionic circuits using ions as charge carriers have demonstrated great potential for flexible and bioinspired electronics. The emerging ionic thermoelectric (iTE) materials can generate a potential difference by virtue of selective thermal diffusion of ions, which provide a new route for thermal sensing with the merits of high flexibility, low cost, and high thermopower. Here, ultrasensitive flexible thermal sensor arrays based on an iTE hydrogel consisting of polyquaternium‐10 (PQ‐10), a cellulose derivative, as the polymer matrix and sodium hydroxide (NaOH) as the ion source are reported. The developed PQ‐10/NaOH iTE hydrogel achieves a thermopower of 24.17 mV K−1, which is among the highest values reported for biopolymer‐based iTE materials. The high p‐type thermopower can be attributed to thermodiffusion of Na+ ions under a temperature gradient, while the movement of OH− ions is impeded by the strong electrostatic interaction with the positively charged quaternary amine groups of PQ‐10. Flexible thermal sensor arrays are developed through patterning the PQ‐10/NaOH iTE hydrogel on flexible printed circuit boards, which can perceive spatial thermal signals with high sensitivity. A smart glove integrated with multiple thermal sensor arrays is further demonstrated, which endows a prosthetic hand with thermal sensation for human–machine interaction.

Thermogalvanic hydrogel-based e-skin for self-powered on-body dual-modal temperature and strain sensing

“…Their ability to retain a high water content, similar to human tissue, renders them an ideal candidate for electronic skin 27 – 29 . An increasing number of ion-conductive hydrogels have achieved heat-to-electrical energy conversion, depending on the thermodiffusion effect 30 , 31 , the thermogalvanic effect 32 , 33 , and synergistic effects 34 . Based on the abovementioned skin-like gels, significant progress has also been made in temperature 35 , pressure 36 , 37 , and strain sensing 38 , 39 .…”

Enhancement of ZT in Bi0.5Sb1.5Te3 Thin Film through Lattice Orientation Management

“…Their portability, scalability, and ability to operate based on temperature differentials distinguish them from conventional heat engines. TEGs provide uninterrupted energy for various applications, including self-powered wearable electronics [1][2][3][4], autonomous devices, thermal sensing, and energy harvesting. In the quest to improve thin-film thermoelectric generators (TEGs) for energy harvesting, selecting materials with high energy conversion efficiency is crucial.…”

High Seebeck Coefficient Inorganic Ge15Ga10Te75 Core/Polymer Cladding Fibers for Respiration and Body Temperature Monitoring

“…Wearable thermal sensors are significant for surveying the environment and contact object temperature and demonstrate great potential in human–machine interactions, intelligent medical systems, and electronic skins. − Fiber-based thermoelectric (TE) devices enable the direct transduction of temperature difference into electrical signals and have the advantages of high reliability, small volume, and noiselessness, making them attractive in high-performance thermal sensing. − In addition, fibers demonstrate great potential for utilization in sensing, food, and lasers owing to their fast response, low cost, superior stability, tunability, and simple manufacturing. − The fibers can be bent in different directions because of their intrinsic flexibility; therefore, they can be easily wrapped around arbitrarily shaped surfaces, providing broad prospects for large-area wearable thermal sensing networks. − …”