A droplet-driven micro-surfboard with dual gradients for programmable motion

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2022-10, Vol.446, p.136874, Article 136874
• Main Authors: Dai, Ruyuan, Li, Guoqiang, Xiao, Lin, Li, Yaoxia, Cui, Zehang, Jia, Long, Zhou, Maolin, Song, Yuegan, Yang, Yi, Cai, Yong, Chen, Changfeng, Yin, Kai
• Format: Article
• Language: English
• Subjects: Directional transportation; Droplet-driven actuator; Dual gradients of geometry and wettability; Femtosecond laser micro/nano fabrication; Programmable motion
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2022.136874

A novel droplet-driven micro-surfboard (DDMS) is developed by femtosecond laser micro/nano fabrication and chemical modification. Just only a droplet can drive the DDMS, which not only achieves linear motion but also can complete curvilinear and rotational motion. Such strategy is promising in the field of micromachines and intelligent systems. [Display omitted] •Conventional self-propelled autonomous devices always require external energy or chemicals to move.•A novel droplet-driven micro-surfboard (DDMS) is developed using femtosecond laser.•Droplet-driven micro-surfboard (DDMS) is composed of a superhydrophobic plate with superhydrophilic wedge groove.•The droplet-driven autonomous devices can realize linear motion, but also complete curve motion and rotary motion. Self-propelled autonomous devices have great significance in energy, environment, and biomedical engineering, and thus vast achievements have been made in recent years. However, conventional propulsion often requires special chemicals or external energy, limiting their practical applications due to environmental pollution and energy waste. In this work, inspired by the character of a water strider on the water surface, a novel droplet-driven micro-surfboard (DDMS) is developed via femtosecond laser micro/nano fabrication, which can be driven in a green and controllable way. The DDMS is composed of a superhydrophobic sheet with superhydrophilic wedgy grooves. The droplet is put on superhydrophilic wedgy grooves to enter the water and form a jet, which further facilitates the directional motion of the DDMS. Also, a type of actuator with three superhydrophilic wedgy grooves is designed successively to achieve turn direction, which completes the programable motion by adding droplets to the three channels. Finally, an actuator with circular water storage area and a symmetrical vane-like rotating device with two superhydrophilic channels are developed, realizing long-distance and rotational motions. This work provides new insights into pollution-free autonomous devices and shows the great potential of droplet-driven autonomous devices in the fields of micromechanics and intelligent systems.