Ultrarobust alginate-based temperature sensing fiber across subzero to above zero self-healing performance enabled by polyphenol-nanosphere engineered multiple dynamic bonds

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-Fe 3+ 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 Ti 3 C 2 T 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 , R 2  =  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.