Wind Tweezer for Versatile Droplet Manipulation on the Femtosecond Laser-Structured Superhydrophobic Platform

Area of Science:

• Fluid Dynamics
• Microfluidics
• Nanotechnology

Background:

• Existing noncontact droplet manipulation methods (optical, magnetic, electrical, acoustic) face limitations.
• These methods often require responsive additives or alter droplet properties.

Purpose of the Study:

• To introduce a wind tweezer (WT) for precise, remote, and programmatic droplet manipulation.
• To overcome the limitations of current droplet manipulation techniques.

Main Methods:

• Development of a wind tweezer (WT) system utilizing controlled airflow (wind force).
• Formulation of a comprehensive equation to characterize wind force on droplets.
• Demonstration of manipulation across various droplet volumes, compositions, and velocities.

Main Results:

• The WT system precisely manipulates droplets (100 nL to 3 mL) with variable properties and high velocities (up to 160 mm/s).
• Successful manipulation of droplet arrays, Leidenfrost droplets, and vertical droplet movement.
• Demonstrated applications in circuit repair, cell transport, and enhanced SERS detection.

Conclusions:

• The wind tweezer offers a versatile, precise, and flexible solution for noncontact droplet manipulation.
• This technology has significant potential in microfabrication, biological applications, and advanced sensing.