Fabrication of a Three-Layer PDMS Pneumatic Microfluidic Chip for Micro Liquid Sample Operation

Area of Science:

• Materials Science
• Microfluidics Engineering

Background:

• Microfluidic devices are crucial for precise sample manipulation.
• Fabrication of polydimethylsiloxane (PDMS) chips often requires optimization for specific applications.

Purpose of the Study:

• To develop a robust fabrication method for a three-layer PDMS chip for micro liquid sample operation.
• To investigate methods for improving microchannel geometry and PDMS layer properties.

Main Methods:

• Fabrication of rectangular control layer microchannels using a dry-film negative photoresist mold.
• Fabrication of rounded liquid layer microchannels using a positive photoresist reflow mold, exploring reflow temperature and time effects.
• Optimization of PDMS layer properties (toughness, plasticity) through varying ratios, curing temperatures, and times.
• Surface modification of PDMS using oxygen plasma treatment to enhance surface properties and sealing strength.

Main Results:

• Successful fabrication of a three-layer PDMS chip with distinct microchannel cross-sections.
• Demonstrated control over liquid layer mold arc level via reflow parameters.
• Oxygen plasma treatment improved PDMS surface properties, reducing processing temperature and time while enhancing sealing strength.
• Achieved high levels of pinching off and mixing performances in micro liquid sample operations on the pneumatic microfluidic chips.

Conclusions:

• The developed fabrication technique enables efficient production of PDMS microfluidic chips with improved performance.
• Optimized PDMS properties and surface treatments are key to achieving superior sealing and operational characteristics.
• The study provides a valuable methodology for advancing microfluidic device design and application in sample handling.