Polydimethylsiloxane Surface Modification of Microfluidic Devices for Blood Plasma Separation

Area of Science:

• Biomedical Engineering
• Materials Science
• Analytical Chemistry

Background:

• Microfluidic devices are crucial for analytical and clinical diagnostics, enabling biological sample processing.
• Polydimethylsiloxane (PDMS) is widely used but its hydrophobic nature hinders performance in applications like plasma separation.
• Hydrophobic surfaces cause poor wetting, fluid mixing issues, and reduced efficiency in biomolecule detection and plasma separation.

Purpose of the Study:

• To investigate surface modification methods for creating hydrophilic PDMS microfluidic devices.
• To evaluate the effectiveness of different surfactants and modification techniques for improving PDMS wettability.
• To enhance the efficiency of blood plasma separation in microfluidic devices.

Main Methods:

• Fabrication of microfluidic devices using stereolithography and PDMS double casting.
• Surface modification of PDMS using bulk mixture and surface immersion methods with Pluronic® F127, polyethylene glycol (PEG), and polyethylene oxide (PEO) surfactants.
• Characterization of surface wettability using water contact angle (WCA) measurements and capillary flow studies.

Main Results:

• PDMS surfaces modified with polyethylene oxide (PEO) surfactant at 2.5% (v/v) exhibited the best hydrophilic properties (WCA < 50°) for extended periods.
• The PEO-modified PDMS surfaces maintained optical properties without degradation.
• Capillary flow studies demonstrated improved fluid handling and reduced air bubble trapping in modified microchannels.

Conclusions:

• PDMS surface modification, particularly with PEO, significantly enhances hydrophilicity and performance of microfluidic devices.
• Improved wettability facilitates blood plasma separation, reduces cell aggregation, and minimizes air bubble issues.
• This approach offers a promising strategy for developing more efficient and reliable microfluidic diagnostic tools.