Lee, Ling ChiehLing ChiehLeeHuang, Kang TingKang TingHuangLin, Yen-TingYen-TingLinJeng, U. SerU. SerJengWang, Chia HsinChia HsinWangSHIH-HUANG TUNGHuang, Chun JenChun JenHuangCHENG-LIANG LIU2024-03-052024-03-052024-01-0116136810https://scholars.lib.ntu.edu.tw/handle/123456789/640280Amid growing interest in using body heat for electricity in wearables, creating stretchable devices poses a major challenge. Herein, a hydrogel composed of two core constituents, namely the negatively-charged 2-acrylamido-2-methylpropanesulfonic acid and the zwitterionic (ZI) sulfobetaine acrylamide, is engineered into a double-network hydrogel. This results in a significant enhancement in mechanical properties, with tensile stress and strain of up to 470.3 kPa and 106.6%, respectively. Moreover, the ZI nature of the polymer enables the fabrication of a device with polar thermoelectric properties by modulating the pH. Thus, the ionic Seebeck coefficient (Si) of the ZI hydrogel ranges from −32.6 to 31.7 mV K−1 as the pH is varied from 1 to 14, giving substantial figure of merit (ZTi) values of 3.8 and 3.6, respectively. Moreover, a prototype stretchable ionic thermoelectric supercapacitor incorporating the ZI hydrogel exhibits notable power densities of 1.8 and 0.9 mW m−2 at pH 1 and 14, respectively. Thus, the present work paves the way for the utilization of pH-sensitive, stretchable ZI hydrogels for thermoelectric applications, with a specific focus on harvesting low-grade waste heat within the temperature range of 25–40 °C.enhydrogel | ionic Seebeck coefficient | ionic thermoelectrics | low-grade heat harvesting | zwitterionic polymerjournal article10.1002/smll.202311811383725002-s2.0-85185111389https://api.elsevier.com/content/abstract/scopus_id/85185111389