Ultrarobust alginate-based temperature sensing fiber across subzero to above zero self-healing performance enabled by...

Polysaccharide-based self-healing sensing fibers offer a promising green and durable pathway for wearable electronics, yet their effective healing ability in subzero environments still faces significant challenges. Herein, we present a subzero self-healing temperature-sensing (SST) fiber by incorporating tannic acid-Fe³⁺ self-assembled nanospheres (TAN) into a sodium alginate/oxidized sodium alginate/carboxymethyl chitosan matrix. The synergy of multiple dynamic bonds and a rapid local molecular rearrangement mechanism with low activation energy endows SST sensing fiber with exceptional self-healing capabilities at subzero temperatures, achieving a strength retention of 65.7% at -10 °C after being cut. Specifically, the addition of TAN significantly enhances the stretchability (approximately 65%) of SST sensing fibers and exhibits remarkable water-responsive self-healing efficiency (97.64% at 25 °C). In addition, incorporating Ti₃C₂T_x MXene nanosheets endows the SST fiber with broad temperature-sensing capability from 50 to 500 °C, attributed to the linear correlation between output voltage intensity and temperature (U_max = 0.0115T - 0.1582, R² = 0.99). Furthermore, the SST fiber integrated with a wireless system demonstrates rapid response times (1.7 s) and reliable cyclic stability in temperature detection. This work provides a viable approach for designing bio-based temperature-sensing fibers that possess wide-temperature-adaptive self-healing ability for enhanced reliability and durability in practical wearable applications.