Microvalve array fabrication using selective PDMS (polydimethylsiloxane) bonding through Perfluorooctyl-trichlorosilane passivation for long-term space exploration

Abstract

To improve the versatility and robustness of microfluidic analytical devices for space exploration, a programmable microfluidic array (PMA) has been implemented to support a variety of missions. When designing a PMA, normally closed valves are advantageous to avoid cross contamination and leaking. However, a stable fabrication method is required to prevent these valves from sticking and bonding over time. This work presents how polydimethylsiloxane (PDMS) can be bonded selectively using chemical passivation to overcome PDMS sticking issue during long-term space exploration. First, on a PDMS stamp, the vaporized perfluorooctyl-trichlorosilane (PFTCS) are deposited under − 80 kPa and 150 °C conditions. The PFTCS was then transferred onto PDMS or glass substrates by controlling temperature and time and 15 min at 150 °C provides the optimal PFTCS transfer for selective bonding. With these characterized parameters, we successfully demonstrated the fabrication of PMA to support long-term space missions. To estimate the stability of the stamped PFTCS, a PMA has been tested regularly for three years and no stiction or performance alteration was observed. A flight test has been done with a Cessaroni L1395 rocket for high g-force and vibration test and there is no difference on PMA performance after exposure of launch and landing conditions. This work shows promise as a simple and robust technique that will expand the stability and capability of PMA for space exploration.

A simple and reliable microfabrication process for a programmable microvalve array

“…A selective bonding strategy is necessary to avoid unwanted bonding of the PMA gate structures to the underlying the glass substrates. In our approach of selective bonding, we utilize a unique microcontact printing technique to passivate the gate [21] . This approach utilizes Perfluorooctyl-Trichlorosilane (PFTCS, CAS: 78560-45-9) that has been placed on a masked PDMS stamp and pressed onto the gate structures prior to bonding.…”

Self-Healing Transparent Poly(dimethyl)siloxane with Tunable Mechanical Properties: Toward Enhanced Aging Materials for Space Applications

“…In addition, its resistance to UV and its transparency make it suitable for numerous space applications. 2,3 Indeed, PDMS is widespread in satellites and used in sensors, thermal and electrical insulators, or even adhesives. 4,5 However, the prolonged irradiation to energetic particles causes the aging of the materials such as cracking and a decrease of optical properties.…”

Operation of a programmable microfluidic organic analyzer under microgravity conditions simulating space flight environments

“…The Lunar and Martian cases pumped 99.25±0.1% and 99.4±0.6% of the level flight average, respectively. This level of variation is common over longer period flowrate testing 22 and corresponds to ~3nL of difference overall volume per cycle. However, the volume pumped per cycle during hypergravity was 94±1.1% of the average value during level flight.…”

“…Figure 1A shows the MOA system, including the PMA-µCE chip, manifold and LIF detection system, and sensor suite. The chip presented in Figure 1B shows the rectilinear array of the microvalves acting as the fluidic processor as well as the other microvalves for controlling fluidic path and reagent selection [21][22][23] . The chip is mounted on the manifold shown in Figure 1C for pneumatic connections that control the PMA-µCE chip.…”