Liquid seal for compact micropiston actuation at the capillary tip

Area of Science:

• Biomedical Engineering
• Microfluidics
• Nanotechnology

Background:

• Classical mechanical actuators face significant challenges at the microscale due to dominant frictional forces.
• Submillimetric catheter-based actuators are crucial for in vivo cellular-scale interventional procedures like biopsy and manipulation.

Purpose of the Study:

• To design and fabricate a novel microscale piston actuator for submillimetric catheters.
• To overcome the limitations of friction in microscale actuation for enhanced in vivo procedures.

Main Methods:

• Fabrication of a microscale piston (max dimension 150 μm) using two-photon lithography on capillary tips (140-μm diameter).
• Utilized an oil drop method to create a leak-proof seal (up to 185 mbar) with lubricated friction.
• Integrated the piston with a microgripper for manipulation of microspheres.

Main Results:

• The microscale piston generated forces linearly increasing with pressure up to 130 μN without seal failure.
• The oil seal effectively prevented leakage and provided lubricated friction.
• Demonstrated practical application by grasping and moving 50-μm microspheres with the integrated microgripper.

Conclusions:

• The developed microscale piston actuator is a viable solution for overcoming friction at cellular scales.
• This technology enables micrometer-size catheter actuation, paving the way for advanced minimally invasive procedures.
• The design holds significant potential for applications in cellular biopsy, manipulation, and micro-optics support.