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Surface characterization using chemical force microscopy and the flow performance of modified polydimethylsiloxane
Bin Wang1, Zamin Abdulali-Kanji, Emily Dodwell
1Department of Chemistry, Queen's University, Kingston, Ontario, Canada.
Electrophoresis
|May 6, 2003
Summary
Researchers modified polydimethylsiloxane (PDMS) microfluidic devices to improve flow. Surface oxidation enhanced electroosmotic flow (EOF) similar to glass, while amine modification slowed it, enabling tailored device performance.
Area of Science:
- Materials Science
- Analytical Chemistry
- Microfluidics
Background:
- Micro total analysis systems (µTAS) traditionally use expensive glass or silicon.
- Polydimethylsiloxane (PDMS) offers a cheaper alternative for microfluidic devices.
- Controlling surface properties is crucial for optimizing microfluidic device performance.
Purpose of the Study:
- To develop a facile method for modifying PDMS surfaces to control electroosmotic flow (EOF).
- To compare the EOF performance of modified PDMS with conventional glass devices.
- To characterize surface modifications using chemical force microscopy.
Main Methods:
- PDMS surface oxidation using Tesla coil discharge.
- Chemical modification of PDMS surfaces with amine groups (APTES).
- Preparation of PDMS replicas using a two-step micromolding protocol.
- Measurement of EOF in modified and unmodified PDMS devices.
- Surface analysis using chemical force microscopy.
Main Results:
- Oxidized PDMS exhibited significantly faster EOF, comparable to glass devices.
- Amine-modified PDMS (APTES) showed reduced flow rates due to surface charge masking.
- Surface modifications effectively altered EOF characteristics as predicted.
- Chemical force microscopy provided insights into surface acid/base properties.
Conclusions:
- PDMS surface modification is an effective strategy to tune EOF for specific microfluidic applications.
- Tesla coil oxidation and APTES derivatization offer controllable methods for surface manipulation.
- Characterization with chemical force microscopy validates the surface modification efficacy.
- Tailored PDMS surfaces can enhance the utility of low-cost microfluidic devices.