Printable and Self-Healing Gelatin Conductive Ink for Dielectric Elastomer Actuators and Strain Sensors

Dielectric elastomer actuators are attracting attention because they can be used for artificial muscles and soft robotics. However, they still remain challenge to demonstrate long-term stable actuators and high movement actuators because most soft materials constituting devices are vulnerable to under external damage during repeated operation and unrecoverable after being subjected to damage. To solve these problems, conductors was given self-healing capability. Some reports suggested technique for self-healing ionic gel but they resulted toxicity and complex fabrications caused by doped electrolytes, ions and macromolecular in order to increase ion conductivity and self-healing properties. In our study, we used non-toxic and bio-compatible gelatin, tannic acid and deep eutectic solvent. Our gelatin-tannic acid gels have good mechanical property and self-healing efficiency, and these gels satisfied the ink condition suitable for direct printing during a programmed electrohydrodynamic printing process. As a result, it was possible to desired patterns of gelatin conductors were successfully obtain easily, which strain sensors and electrode for dielectric elastomer actuators could be easily fabricated with desired patterns. Dielectric elastomer actuators are fabricated in this method exhibit high movements and self-healing efficiency of ~26.3% and ~ 96.8%.