Soft Spiral‐Shaped Microswimmers for Autonomous Swimming Control by Detecting Surrounding Environments

Abstract

In nature, most microorganisms have motility, which is essential for their survival or reproduction. To move, some microorganisms have evolved soft spiral-shaped flagella, which rotate through specialized motors. Many of these microorganisms can change the morphology of their spiral-shaped flagella to control their motility. Herein, by mimicking these flagella, spiral-shaped microswimmers are developed for various applications, such as target drug delivery, micro-object transport, and micro-fluid manipulation. In previous studies, numerous fabrication methods of spiral-shaped microswimmers are developed. However, the swimming direction and velocity are controlled only by external systems, such as magnetic fields, because the spiral body is not able to deform. Therefore, this soft spiral-shaped microswimmer for autonomous swimming control by detecting surrounding stimuli is proposed. The velocity of microswimmer largely depends on the geometry of the microswimmer's body. Through usage of a stimuli-responsive hydrogel in the microswimmer, the geometry autonomously changes in response to the surrounding stimuli. Using finite-element simulation, it is revealed that the pattern angle is an important parameter for acceleration/deceleration of the microswimmer. The dimensionless velocity of the fabricated bilayered spiral swimmer changes by deforming the geometry in response to the surrounding thermal stimuli.