Molding of deep polydimethylsiloxane microstructures for microfluidics and biological applications

Area of Science:

• Materials Science
• Microfabrication
• Biotechnology

Background:

• Polydimethylsiloxane (PDMS) is widely used in microfluidics and biological applications.
• Microfabrication of silicon (Si) molds is crucial for creating PDMS microstructures.
• Existing methods for Si mold fabrication can be complex or expensive.

Purpose of the Study:

• To demonstrate the microfabrication of deep polymeric microstructures using replica-molding PDMS from Si substrates.
• To investigate and compare two methods for microfabricating Si molds.
• To showcase the application of these PDMS microstructures in selective cell delivery.

Main Methods:

• Replica-molding of deep (> 25 microns) PDMS microstructures from microfabricated Si substrates.
• Investigated two Si mold fabrication methods: deep plasma etch of silicon-on-insulator (SOI) wafers and photolithographic patterning of a spin-coated photoplastic layer.
• Demonstrated selective delivery of cell suspensions to create micropatterns of attached cells.

Main Results:

• Achieved microfabrication of deep polymeric microstructures using PDMS replica-molding.
• Photoplastic method for Si mold fabrication, while lower resolution than SOI, offered similar replication fidelity at a lower cost.
• Replication fidelity was primarily limited by the mechanical stability of the PDMS structures.
• Successfully demonstrated selective cell delivery for micropatterning.

Conclusions:

• The photoplastic-based Si mold fabrication offers a cost-effective approach for creating PDMS microstructures.
• The developed technique is suitable for applications requiring precise cell patterning, such as in tissue engineering and microfluidics.
• Further improvements in PDMS mechanical stability could enhance replication fidelity for even finer features.