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Monolithic valves for microfluidic chips based on thermoresponsive polymer gels
Quanzhou Luo1, Senol Mutlu, Yogesh B Gianchandani
1Department of Chemistry, University of California, Berkeley, CA 94720-1460, USA.
Electrophoresis
|November 13, 2003
Summary
Thermoresponsive monolithic copolymers were developed as microfluidic valves. These smart polymer valves rapidly switch between open and closed states, enabling precise fluid control in microdevices.
Area of Science:
- Polymer Science
- Microfluidics
- Materials Science
Background:
- Microfluidic devices require precise fluid control.
- Developing non-mechanically actuated valves is crucial for advanced microfluidic systems.
- Thermoresponsive polymers offer unique properties for dynamic valve applications.
Purpose of the Study:
- To develop thermoresponsive monolithic copolymers for use as microfluidic valves.
- To investigate the direct preparation of these copolymers via photopatterning.
- To characterize their performance as non-mechanically actuated valves.
Main Methods:
- Photopatterning of aqueous solutions containing N-isopropylacrylamide, N-ethylacrylamide, and cross-linkers.
- Utilizing the lower critical solution temperature (LCST) phase transition for valve actuation.
- Measuring pressure resistance, flow resistance, and actuation times.
Main Results:
- Successfully prepared thermoresponsive monolithic copolymers as microfluidic valves.
- Valves exhibited rapid swelling/deswelling at their LCST, enabling channel closure/opening.
- Adjustable LCST range (35-74°C) by varying monomer ratios.
- Closed valves withstood pressures up to 18 MPa without leakage.
- Fast actuation times (1-4 s) and high durability over repeated cycles.
Conclusions:
- Thermoresponsive monolithic copolymers are effective non-mechanically actuated valves for microfluidics.
- Photopatterning offers a direct route for valve fabrication.
- These valves demonstrate robust performance, fast response, and tunable properties.