Induced hydraulic pumping via integrated submicrometer cylindrical glass capillaries
Citation
Cao, Z., & Yobas, L. (2014). Induced hydraulic pumping via integrated submicrometer cylindrical glass capillaries. Electrophoresis, 35(15-16), 2353–2360.
Keywords
- Capillary
- Chromatography
- Microfluidics
- Micropump
- Surface charge
Brief
Researchers demonstrate a micropump that utilizes varying conductance in submicrometer cylindrical glass capillaries at low salt concentrations to generate hydraulic pressure, achieving a pressure of 5 kPa at 700 V and demonstrating the ability to perform open-tubular liquid chromatography separation of amino acids with this device.
Summary
This article presents a novel micropump that leverages the differential electrical conductance of submicrometer glass capillaries at low salt concentrations to generate hydraulic pressure. This pressure is then used to drive an open-tubular liquid chromatography (LC) system, demonstrating the micropump's utility in bioanalytical applications.
Here are some key findings from the article:
- The study found that the electrical conductance of the capillaries deviates from typical bulk linear behavior at low salt concentrations. Instead, the conductance gradually decreases with decreasing salt concentration, which is better explained by a variable surface charge model that considers the chemical equilibrium of the glass surface.
- The micropump, operating at 700 V, generated a hydraulic pressure of 5 kPa, resulting in a flow velocity of up to 3 mm/s in the field-free microchannel.
- This pressure-driven flow enabled the successful separation of three amino acids in under 20 seconds using open-tubular LC, demonstrating comparable or better efficiency than other integrated pump-driven LC systems with plate heights ranging from 3–7 μm.
- The authors suggest that the micropump design can be further optimized by adjusting capillary dimensions and increasing the number of capillaries to enhance its performance.
This research highlights a promising approach for creating a compact and efficient micropump for various bioanalytical applications.