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Tailoring the surface properties of poly(dimethylsiloxane) microfluidic devices
Shuwen Hu1, Xueqin Ren, Mark Bachman
1Center for Biomedical Engineering, Integrated Nanosystems Research Facility, Department of Electrical and Computer Engineering, University of California, Irvine, California 92697, USA.
Langmuir : the ACS Journal of Surfaces and Colloids
|July 1, 2005
Summary
Researchers developed a UV grafting method to customize poly(dimethylsiloxane) (PDMS) surfaces for microfluidic devices. This technique allows tunable surface properties, overcoming limitations for microelectrophoresis applications.
Area of Science:
- Materials Science
- Surface Chemistry
- Microfluidics
Background:
- Poly(dimethylsiloxane) (PDMS) is a versatile material for microfluidic applications due to its favorable properties like ease of fabrication, low cost, and optical transparency.
- However, the inherent surface properties of PDMS limit its widespread use in microelectrophoresis compared to glass, primarily due to challenges in surface modification.
- Tailoring PDMS surface properties is crucial for optimizing its performance in various microfluidic applications, particularly those involving electrophoresis.
Purpose of the Study:
- To develop a facile and effective method for customizing the surface properties of PDMS microfluidic channels.
- To demonstrate the ability to tune surface characteristics, such as surface charge and hydrophobicity, by controlling monomer ratios during UV grafting.
- To assess the stability and performance of the modified PDMS surfaces in microelectrophoretic applications.
Main Methods:
- A one-step UV grafting process was employed using co-mixed neutral and charged monomers to modify PDMS surfaces.
- Different ratios of four neutral monomers and two charged monomers were grafted onto PDMS.
- Functional microfluidic channels were fabricated from modified PDMS halves, and their surface properties were characterized.
Main Results:
- The UV grafting method successfully customized the surface properties of PDMS microfluidic channels.
- By varying the ratio of co-mixed monomers, a wide range of surface properties, including electrophoretic mobilities between +4 x 10(-4) cm2/(V s) and -2 x 10(-4) cm2/(V s), were achieved.
- The modified PDMS surfaces exhibited stable contact angles and electrophoretic mobilities over time and upon exposure to air.
Conclusions:
- UV grafting of co-mixed monomers offers a simple and effective approach to tailor PDMS surface properties for microfluidic applications.
- This method enables precise control over surface characteristics, expanding the utility of PDMS in microelectrophoresis and other fields.
- The demonstrated tunability and stability of modified PDMS surfaces pave the way for customized microfluidic device fabrication.