A Highly Stretchable, Ultrastable, and Antifatigue Ionic Organogel as an Environment-Tolerant Flexible Sensor and Sensitive Capacitive Pen

High-performance flexible sensors require excellent temperature and fatigue resistance without a significant sacrifice of high sensitivity. In this study, an environmentally resistant ionic organogel was fabricated via a two-step approach. An ultrastable binary solvent system was first synthesized using ethylene glycol and halogenated metal ionic liquid. Then, a loosely chemically cross-linked poly(acrylic acid) was incorporated as a backbone in the binary solvent, in which graphene oxide and halogenated metal ionic liquids synergistically formed an efficient conductive network. The distinct binary solvent and ample interactions endowed the gel with remarkable stretchability (elongation at break of 1105%), superior fatigue resistance (mechanical loss of only 4.05% after 500 compression cycles), and stable mechanical properties over a wide temperature range (from −80 to 150 °C). Additionally, its mechanical properties could be preserved to a great extent after 15 days of exposure to an open environment. Due to its outstanding conductivity and sensing capabilities, the gel is also suitable for transmitting Morse code signals or being integrated into capacitive pens for seamless digital screen interaction. This multifunctional ionic organogel holds great promise for applications in electronic skin, motion monitoring, and human machine interaction (HMI) in extreme environments.