Stretchable, Healable, and Degradable Soft Ionic Microdevices Based on Multifunctional Soaking-Toughened Dual-Dynamic-Network Organohydrogel Electrolytes

Electronic materials and devices that can mimic biological systems featured with elasticity, toughness, self-healing, degradability, and environmental friendliness drive the technological developments in fields spanning from bioelectronics, biomedical diagnosis and therapy, electronic skin, and soft robotics to Internet-of-Things with “green” electronics. Among them, ionic devices based on gel electrolytes have emerged as attractive candidates for biomimetic systems. Herein, we presented a straightforward approach to demonstrate soft ionic microdevices based on a versatile organohydrogel platform acting as both a free-standing, stretchable, adhesive, healable, and entirely degradable support and a highly conductive, dehydration- and freezing-tolerant electrolyte. This is achieved by forming a gelatin/ferric-ion-cross-linked polyacrylic acid (GEL/PAA) dual dynamic supramolecular network followed by soaking into a NaCl glycerol/water solution to further toughen the gelatin network via solvent displacement, thus obtaining a high toughness of 1.34 MJ·cm–3 and a high ionic conductivity (>7 mS·cm–1). Highly stretchable and multifunctional ionic microdevices are then fabricated based on the organohydrogel electrolytes by simple transfer printing of carbon-based microelectrodes onto the prestretched gel surface. Proof-of-concept microdevices including resistive strain sensors and microsupercapacitors are demonstrated, which displayed outstanding stretchability to 300% strain, resistance to dehydration for >6 months, autonomous self-healing, and rapid room-temperature degradation within hours. The present material design and fabrication approach for the organohydrogel-based ionic microdevices will provide promising scope for life-like and sustainable electronic systems.