Bulk modification of polymeric microfluidic devices

Area of Science:

• Materials Science
• Chemical Engineering
• Microfluidics

Background:

• Surface properties of microfluidic devices significantly influence fluid dynamics.
• Existing methods for surface modification can be complex and time-consuming.

Purpose of the Study:

• To develop an effective bulk modification route for controlling surface chemistry and performance of polymeric microfluidic chips.
• To introduce functional moieties (carboxy, sulfo, amino) into polymer substrates during fabrication.
• To enhance electroosmotic flow (EOF) and pH sensitivity in plastic microchips.

Main Methods:

• Tailored copolymerization of monomers during atmospheric-pressure molding to modify the bulk microchip material.
• Incorporation of methylacrylic acid (MAA), 2-sulfoethyl-methacrylate, and 2-aminoethyl-methacrylate monomers.
• Investigating the effects of modifier loading and pH on EOF in modified poly(methylmethacrylate) (PMMA) microchips.

Main Results:

• A 6% MAA-modified PMMA microchip showed a significant increase in electroosmotic mobility (from 2.12 to 4.30 x 10(-4) cm(2) V(-1) s(-1)).
• A 3% aminoethyl modified PMMA microchip demonstrated reversed electroosmotic mobility (-5.6 x 10(-4) cm(2) V(-1) s(-1) at pH 3.0).
• Modified devices exhibited reproducible, stable EOF behavior with pH sensitivity.

Conclusions:

• Bulk modification during fabrication is an effective strategy for enhancing polymeric microchip performance.
• The developed protocol allows for tunable surface properties, including controlled EOF and pH sensitivity.
• This one-step fabrication/modification process facilitates the widespread production of high-performance plastic microfluidic devices.