Coherent anti-Stokes Raman scattering microscopy for quantitative characterization of mixing and flow in...

Area of Science:

• Optics and Photonics
• Microfluidics
• Chemical Engineering

Background:

• Characterizing fluid flow in microfluidic devices is crucial for many applications.
• Traditional methods can be invasive or require labeling, complicating analysis.
• Developing noninvasive techniques is essential for accurate microscale flow studies.

Purpose of the Study:

• To present an optical, noninvasive, and label-free method for characterizing flow profiles in microfluidic devices.
• To demonstrate the capability of mapping mass transport and relating it to local flow rates.
• To validate the technique in different microfluidic channel geometries.

Main Methods:

• Utilized Coherent Anti-Stokes Raman Scattering (CARS) signals to probe mass transport.
• Developed a method to relate CARS signals to the local flow rate of dilute solutes.
• Applied the technique to polydimethylsiloxane/glass square channels and wet-etched glass tapered channels.

Main Results:

• Successfully mapped mass transport within microfluidic devices.
• Established a correlation between mass transport mapping and local flow rates.
• Demonstrated the versatility of the technique across different microchannel types.

Conclusions:

• The presented CARS-based approach offers an effective optical, noninvasive, and label-free solution for microfluidic flow characterization.
• This method provides valuable insights into solute transport and flow dynamics at the microscale.
• The technique is applicable to various microfluidic device designs, enhancing experimental possibilities.