Anti-freezing and long-term stabilized photonic-ionic organogels for high sensitive wearable motion sensors

• An application of the Hofmeister effect to structural color modulation. • Extremely sensitive and highly synergistic dual signal feedbacks. • Good frost protection and low-temperature ambient sensing capability. • Long-term stability in air at room temperature (20 °C-50 % RH). • Building a wireless wearable sensing device with microcontrollers. Flexible and stretchable sensors are promising for wearable devices applications, due to their lightweight, adaptivity, and biocompatible nature. However, reported sensors often face electrical signal feedback, narrow operational temperature range and low moisture stability, limiting their practical applications. Here, we report a high-performance Photonic-Ionic organogels (PIOs) based on the Hofmeister effect possessing optical and electrical dual signal feedbacks, anti-freezing and long-term stability via the rational design of the magnetic self-assembly strategy and solvent displacement treatment. The arrangement and orientation of photonic crystals (Fe 3 O 4 @C) within a gelatin-acrylamide double network gel matrix provides PIOs with interesting optical signal feedbacks. The following solvent displacement with glycerol and salt lithium chloride introducting conductivity and anti-freezing performance. The PIOs achieve dynamic equilibrium of water loss and swelling during this period and maintain the structural color stable (due to the Hofmeister effect). Furthermore, the optimized PIOs exhibit superior optical and electrical dual-signal sensing sensitivity with a gauge factor of 3.331 (80 % strain), a response time of 280 ms, a mechanochromic sensitivity of 1.88 nm per percent strain, as well as demonstrate robust low temperature tolerance (from −40 °C ∼ 20 °C) and long-term stability in air at room temperature (20 °C ∼ 50 % RH) for 15 days without water loss (>100 %). Significantly, the PIOs could withstand extreme environmental conditions, spontaneous self-regenerate from a normal humidity environment and restore their initial optical and electrical sensing property. A wireless sensing system was built using PIOs and microcontrollers that, thereby offering a new strategy for the development of stable, sensitive, and multi-functional wearable motion sensors.