In-situ multicore fibre-based pH mapping through obstacles in integrated microfluidic devices

Area of Science:

• Microfluidics and Sensor Technology
• Analytical Chemistry
• Optical Engineering

Background:

• Microfluidic systems are valuable for studying multiphase flow, reactive transport, and medical/engineering modeling.
• Current optical fiber sensing in microfluidics uses single-core fibers, limiting spatial resolution.
• High-resolution in-situ sensing is crucial for understanding complex microscale phenomena.

Purpose of the Study:

• To develop and demonstrate a multicore fiber-based pH sensing system for microfluidic devices.
• To achieve in-situ pH mapping with micrometer spatial resolution.
• To overcome the spatial resolution limitations of existing single-core fiber systems.

Main Methods:

• Utilized custom laser-manufactured glass microfluidic devices (micromodels) with two-port injection systems.
• Integrated a multicore fiber imaging system with a fluorescence-based pH sensor at the fiber end.
• Employed the distinct cores of the multicore fiber as independent measurement channels.

Main Results:

• Successfully demonstrated in-situ pH mapping with tens of micrometer spatial resolution in microfluidic devices.
• Showcased the ability to distinguish particle features within the microfluidic environment through intensity distribution analysis.
• Validated the system's performance in complex scenarios, including measurements through obstacles like glass and rock beads.

Conclusions:

• The proposed multicore fiber system significantly enhances spatial resolution for pH measurements in microfluidics.
• This technology offers a promising platform for detailed in-situ analysis of chemical environments within microfluidic devices.
• The system's ability to resolve features through obstacles opens new possibilities for studying transport phenomena in porous media.