Thermally Induced Knudsen Forces for Contactless Manipulation of a Micro-Object

Area of Science:

• Physics
• Microfluidics
• Nanotechnology

Background:

• Micro-object manipulation often requires physical contact, posing challenges for delicate samples.
• Thermally induced forces in rarefied gases offer potential for contactless manipulation.
• Knudsen forces arise from temperature gradients in rarefied gases.

Purpose of the Study:

• To propose and investigate a novel tweezer-like mechanism for non-contact micro-object trapping.
• To explore the exploitation of thermally induced Knudsen forces for grasping micro-objects.
• To understand the parameters influencing this contactless manipulation mechanism.

Main Methods:

• Utilized the direct simulation Monte Carlo (DSMC) method for numerical simulations.
• Modeled a system with a heated thin plate near a colder micro-object (beam).
• Analyzed pressure differences and resulting forces generated by thermal edge flows.

Main Results:

• Demonstrated a tweezer-like trapping mechanism driven by Knudsen forces.
• Identified pressure differences at the beam's corners and plate's tip as the primary drivers.
• Observed enhanced trapping forces with shorter beam heights and significant temperature differences.

Conclusions:

• Thermally induced Knudsen forces can be effectively used for non-contact micro-object manipulation.
• The proposed mechanism shows dependence on beam height, temperature difference, and Knudsen number.
• This contactless approach offers a promising avenue for micro-assembly and handling.