posted on 2024-01-15, 16:33authored byVipin Kumar, Sarah Ahmad Siraj, Dillip K. Satapathy
Multivapor-responsive biocompatible
soft actuators have immense
potential for applications in soft robotics and medical technology.
We report fast, fully reversible, and multivapor-responsive controlled
actuation of a pure cassava-starch-based film. Notably, this starch-based
actuator sustains its actuated state for over 60 min with a continuous
supply of water vapor. The durability of the film and repeatability
of the actuation performance have been established upon subjecting
the film to more than 1400 actuation cycles in the presence of water
vapor. The starch-based actuators exhibit intriguing antagonistic
actuation characteristics when exposed to different solvent vapors.
In particular, they bend upward in response to water vapor and downward
when exposed to ethanol vapor. This fascinating behavior opens up
new possibilities for controlling the magnitude and direction of actuation
by manipulating the ratio of water to ethanol in the binary solution.
Additionally, the control of the bending axis of the starch-based
actuator, when exposed to water vapor, is achieved by imprinting-orientated
patterns on the surface of the starch film. The effect of microstructure,
postsynthesis annealing, and pH of the starch solution on the actuation
performance of the starch film is studied in detail. Our starch-based
actuator can lift 10 times its own weight upon exposure to ethanol
vapor. It can generate force ∼4.2 mN upon exposure to water
vapor. To illustrate the vast potential of our cassava-starch-based
actuators, we have showcased various proof-of-concept applications,
ranging from biomimicry to crawling robots, locomotion near perspiring
human skin, bidirectional electric switches, ventilation in the presence
of toxic vapors, and smart lifting systems. These applications significantly
broaden the practical uses of these starch-based actuators in the
field of soft robotics.