Long-term hydrolytically stable bond formation for future membrane-based deep ocean microfluidic chemical sensors

Area of Science:

• Materials Science
• Oceanography
• Chemical Engineering

Background:

• Miniaturized chemical analysis systems are crucial for future ocean profiling of dissolved inorganic carbon (DIC) and other analytes.
• Long-term deployment in the deep ocean at high pressure presents significant challenges for sealing incompatible materials in these systems.

Purpose of the Study:

• To demonstrate a high-strength bond sealing method for miniaturized oceanographic chemical analysis systems.
• To enable the development of robust devices for remote environmental chemical analysis and deep-sea DIC depth profiling.

Main Methods:

• Utilized polydimethylsiloxane (PDMS) as a membrane material for efficient CO2 transfer without ion leakage.
• Developed a bonding technique using bis-[3-trimethoxysilylpropyl]amine (BTMSPA) aminosilane coating on poly(methyl methacrylate) (PMMA) manifolds.
• Employed plasma treatment and thermocompressive bond annealing for robust sealing of PDMS to PMMA.

Main Results:

• Achieved long-term stable bonding of thin PDMS membranes to patterned PMMA manifolds.
• Demonstrated device integrity under repeated tape pull and pressure-flow tests for up to six weeks without failure.
• Confirmed PDMS suitability for rapid CO2 transfer with no ion leakage.

Conclusions:

• Successfully demonstrated chemically resistant bonding of membrane materials to thermoplastics, overcoming a major challenge for deep-ocean deployment.
• This breakthrough facilitates the creation of robust, remote environmental chemical analysis systems.
• Paves the way for float-based depth profiling of dissolved inorganic carbon in marine environments.