Achieving High-Speed Retraction in Stretchable Hydrogels

Abstract

Hydrogels mimicking elastomeric biopolymers such as resilin, responsible for power-amplified activities in biological species necessary for locomotion, feeding, and defense have applications in soft robotics and prosthetics. Here, we report a bioinspired hydrogel synthesized through a free-radical polymerization reaction. By maintaining a balance between the hydrophilic and hydrophobic components, we obtain gels with an elastic modulus as high as 100 kPa, stretchability up to 800%, and resilience up to 98%. Such properties enable these gels to catapult projectiles. Furthermore, these gels achieve a retraction velocity of 16 m s^-1 with an acceleration of 4 × 10³ m s^-2 when released from a stretched state, and these values are comparable to those observed in many biological species during a power amplification process. By utilizing and tuning the simple synthetic strategy used here, these gels can be used in soft robotics, prosthetics, and engineered devices where power amplification is desired.

Keywords: bioinspired; highly stretchable gels; hydrophobic interactions; resilient gels; retraction velocity.