Micropumping of Liquids by Directional Growth and Selective Venting of Bubbles

Summary

UCLA researchers in the Department of Mechanical and Aerospace Engineering have invented a micro-scale pumping mechanism that requires no moving parts, operates on low power, and offers greater utility than the present state of the art for both open and closed systems.

Background

Micropumps are a critical element of microfluidics, as they are required to move small volumes of liquid in a controlled, energy-efficient manner. Several categories of micropumps have been reported, such as mechanical micropumps, electrokinetic micropumps, and valveless bubble-driven micropumps. The valveless bubble pumps are attractive for microfluidics because of their simplicity in fabrication over mechanical pumps and their flexibility in working liquids over electrokinetic pumps. The preferred method to date of generating bubbles in the valveless pump is by thermal generation (boiling). However, this method has several limitations. First, boiling requires high levels of energy to induce vapor formation. Second, the vapor condenses back to liquids much slower than they boiled, which limits the cycling speed of the pumping action. Another common bubble generation methods for the valveless pump is electrolysis, but they are not suitable for closed systems, such as fuel cells, because of the inability to eliminate the gas bubbles.

Innovation

This invention provides a compact means to pump a liquid in a microfluidic system by generating, moving, and quickly removing gas bubbles from the system with low power. With existing technology, bubble-driven pumps are made open so that bubbles are expelled with the liquid. In contrast, this invention vents the bubbles (without liquid) quickly through a nano-porous membrane making it applicable in both open and closed fluidic devices.

Applications

• Small fuel cells
• Chromatography
• Biological and chemical sensors
• Lab-on-a-chip microfluidic circuits
• Drug delivery systems such as insulin pumps

Advantages

State Of Development

A device has been fabricated, tested, and characterized in both closed-loop and open-loop configurations.

Other Information

Website: http://cjmems.seas.ucla.edu/

Patent Status