Microvalve array fabrication using selective PDMS (polydimethylsiloxane) bonding through...

Area of Science:

• Materials Science
• Microfluidics
• Aerospace Engineering

Background:

• Microfluidic analytical devices require robust, normally closed valves to prevent contamination and leakage.
• Long-term space missions necessitate microfluidic systems that maintain performance under harsh conditions.
• Polydimethylsiloxane (PDMS) microfluidic valves are prone to sticking and bonding over time, limiting their use.

Purpose of the Study:

• To develop a stable fabrication method for polydimethylsiloxane (PDMS) microfluidic valves.
• To overcome PDMS sticking issues for long-term space exploration applications.
• To enhance the versatility and robustness of programmable microfluidic arrays (PMAs) for space missions.

Main Methods:

• Selective chemical passivation of PDMS substrates using vaporized perfluorooctyl-trichlorosilane (PFTCS).
• Optimized PFTCS deposition and transfer parameters: 150 °C and 15 minutes for optimal transfer.
• Fabrication and testing of a programmable microfluidic array (PMA) using the developed passivation technique.

Main Results:

• Successfully demonstrated the fabrication of PMAs with selective PDMS bonding.
• Three years of regular testing showed no stiction or performance alteration in the PFTCS-treated PMAs.
• A flight test confirmed no performance degradation after exposure to high g-force and vibration during rocket launch and landing.

Conclusions:

• Chemical passivation with PFTCS provides a simple and robust method to prevent PDMS valve sticking.
• The technique significantly enhances the stability and capability of PMAs for long-term space exploration.
• This advancement promises to expand the application of microfluidic devices in demanding environments.