High‐Speed Superhydrophobic Swimmers Propelled by Restricted Droplets

Abstract

Abstract Swimmers that can convert external energy to dynamic movement have shown great potential in different fields; however, their applications are restrained due to the demerits of high cost, environmental pollution, and low efficiency in exiting propelling methods. Herein, droplets are proposed to use whose motions are restricted to fixed positions or specified areas to propel a superhydrophobic swimmer with a superhydrophilic wedge‐shaped pattern effectively. This propelling method by restricted droplets can more effectively convert droplet surface energy to kinetic energy of the superhydrophobic swimmer, thereby achieving high‐efficient propulsion of the swimmer. The propelling mechanism and propelling force are analyzed in detail, and the movement of the swimmer can be controlled by parameters including wedge angle, droplet volume, and needle size. Based on the propelling phenomenon, an accelerator is further developed to promote the hanging droplets to move along specific tracks, and thereby achieve rapid movement of superhydrophobic swimmers on the water surface. In addition, superhydrophobic swimmers capable of reciprocating and precise movement control including position and direction are also designed, which may provide new strategy for movement control of microdevices in intelligent systems.

Keywords

• droplets
• high‐speed
• restricted
• swimmers
• wettability surface