Bioinspired Fast Motion of an Elastomer Bilayer Beam

While plants are traditionally regarded as static, some plants are able to move at accelerations thousands of times the acceleration of gravity. Engineered systems seek to achieve the high accelerations and high speeds observed in nature for use as fast and adaptable materials. Using the inspiration of plant seed pods, we aim to demonstrate that adhesion may act as self-releasing latch when sufficient bending energy is applied to overcome the adhesion of the latch, causing rapid energy release in the form of a bending motion. We prepare a bilayer beam made of polydimethylsiloxane (PDMS) layers with different crosslinking densities, which provides a mechanism for asymmetric swelling and bending when placed in good solvents. Our actuator approaches accelerations 20 times that of gravity and with total response times on the order of 10 ms over cm-scale distances. This work is one step towards increasing the abilities of soft actuators and robots capable of fast motion that are not limited by the requirements of mechanical motors.