High-performance N-type ionic thermoelectric hydrogel for machine learning-assisted self-powered morse code input system

The conversion of human body heat to electricity via the thermoelectric effect delivers a highly promising sustainable power supply strategy for wearable electronic devices. However, the practical application of conventional inorganic thermoelectric materials is severely limited by their inherent high rigidity. Moreover, the solvation effect of water-rich polymer matrices in existing flexible thermoelectric hydrogels greatly hinders anion migration, leaving the research of high-performance n-type thermoelectric hydrogels still underdeveloped. To address the above application bottleneck, this work adopts poly(sulfobetaine methacrylate-co-acrylamide) (poly(SBMA-co-AM)) hydrogel as a superior candidate matrix for low-grade human body heat harvesting, and introduces the I - /I 3 - redox couple to endow the composite hydrogel with excellent ionic thermoelectric conversion performance. This work regulates the synergistic coordination interaction between the I - /I 3 - redox couple and polymer chains, and confirms that the thermal voltage output of the system mainly originates from the redox reaction of I - /I 3 - at the cold and hot electrode interfaces driven by thermal gradient. The hydrogel exhibits excellent thermoelectric stability within a working temperature difference range of 5 K to 45 K, simultaneously achieves a high ionic conductivity (σ) of 0.98 S∙m -1 and an n-type Seebeck coefficient (S i ) of -3.86 mV·K –1 , and maintains stable mechanical fatigue resistance after 1000 continuous loading-unloading cycles. This study provides new insights into the molecular design and thermoelectric modulation mechanism of flexible thermoelectric hydrogels, advances the development of flexible sensors and self-powered systems.