Directional and velocity control of active droplets using a rigid-frame

Area of Science:

• Soft Matter Physics
• Microfluidics
• Robotics

Background:

• Self-propelled oil droplets exhibit spontaneous locomotion driven by Marangoni convection.
• Droplet shape significantly influences locomotion style, with spherical droplets moving randomly and boomerang shapes showing straight motion.

Purpose of the Study:

• To introduce a novel exoskeleton for precise directional and velocity control of self-propelled oil droplets.
• To investigate the influence of exoskeleton-induced boomerang shape on droplet locomotion stability.
• To demonstrate the application of controlled oil droplets in a micro-transporting robot.

Main Methods:

• Fabrication of a novel exoskeleton to impart a boomerang shape to oil droplets.
• Experimental analysis of droplet locomotion dynamics (direction, velocity, stability) under exoskeleton control.
• Integration of controlled oil droplets into a chemically powered micro-robot for object transport.

Main Results:

• Exoskeleton successfully controlled oil droplet directionality, with boomerang shapes exhibiting consistent straight-line motion.
• Locomotion stability was found to be dependent on the specific boomerang geometry.
• Demonstrated successful transport of a floating object using the oil droplet-powered robot.

Conclusions:

• The exoskeleton provides a robust method for directional control of self-propelled oil droplets.
• Exoskeleton-modified droplets can be utilized as micro-robots for targeted transport applications.
• This approach opens avenues for developing autonomous micro-scale machines powered by chemical energy.