Fabrication of organogel strain sensor with self-healing property and extreme temperature tolerance by using phytic acid-liquid metal as initiator

Abstract

Wearable strain sensors have aroused myriad of interest in the domain of electronic skin, soft robotics, and biomedicine. Organogels for wearable strain sensors require desirable stretchability, sensing stability, self-healing property, and a wide working temperature range. However, the synthesis of such organogels typically involves complex and time-consuming processes. Herein, we proposed a rapid copolymerization method for organogels composed of poly(acrylic acid-co-acrylic amide) (P(AA-co-AM)), phytic acid (PA), liquid metal (LM), and polyethylene oxide (PEO). The dispersion of GaInSn in PA solution (GaInSn-PA) was synthesized and employed to initiate the copolymerization of acrylic acid (AA) and acrylic amide (AM), which significantly reduced polymerization time to 2–3 min at room temperature. The release of Ga3+ ions from the LM facilitated cross-linking of P(AA-co-AM) chains through coordination bonds, while also imparted conductivity to the organogel. The synergistic effect between hydrogen bonds and metal coordination bonds extensive within the polymer chains imparted exceptional stretchability (1079 % strain) and self-healing efficiency (98 % at 60 °C) to the organogel. Consequently, the resulting strain sensor demonstrated the ability to accurately monitor both subtle and large human motion, exhibiting remarkable repeatability and durability across a wide temperature range (-20 °C∼40 °C). In addition, the integration of strain sensors on limbs for robotic control through limb movements underscored its practical viability. This optimized fabrication approach and structural design strategy set a new precedent for the development of organogel strain sensors in various applications.