Nonvolatile, stretchable and adhesive ionogel fiber sensor designed for extreme environments

Stretchable conductive sensors based on iontronics are key components for next generation sensing systems in wearable devices or soft robots. Considering the narrow working temperature range of hydrogels-based ionic conductors, ionogel with inherent non-volatility and survivability over a wide temperature range, is proposed to prepare gel fiber-based sensor, via exceedingly simple mold method. Zwitterionic monomer [2-(Methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) (SBMA) and acrylamide (AM) were selected to construct the crosslinked ionogel networks. The ion–dipole, dipole–dipole interactions and interchain hydrogen bonds introduced in the ionogel fiber (IGF) system, simultaneously improve the gel strength and endow the IGF with distinctive properties. The resultant IGF exhibits unique self-adhesiveness, excellent transparency, tunable mechanical properties and ultrahigh stability in various extreme environments. Moreover, as a strain sensor, the as-fabricated IGF is characteristic by outstanding sensitivity with a gauge factor (GF) of 6.20, low detection threshold (0.5% strain) and high durability (1000 cycles at 100% strain). The sensor works well in harsh environments, exhibiting an enlarged working temperature range (–80 ∼ 150 °C) and high tolerance under vacuum (1.325 kPa). We anticipate this IGF-based sensor to make up for the vacancy of flexible sensors in extreme circumstances, thus expanding more application scenarios.