Microscopy imaging and quantitative phase contrast mapping in turbid microfluidic channels by digital holography

Area of Science:

• Optics and Photonics
• Microfluidics
• Biomedical Imaging

Background:

• Microfluidic systems are crucial for biological and chemical analysis.
• Imaging in flowing, turbid media presents significant challenges for conventional microscopy.
• Scattered light from particles typically obscures image quality in dynamic fluid environments.

Purpose of the Study:

• To demonstrate sharp, quantitative phase-contrast imaging in microfluidics with flowing turbid media.
• To present digital holography as a superior technique for overcoming imaging limitations in dynamic fluid samples.
• To validate the method using biological cells as phase objects.

Main Methods:

• Utilizing digital holography for holographic recording and reconstruction.
• Leveraging the Doppler frequency shift of scattered photons from flowing colloidal particles.
• Exploiting the fact that Doppler-shifted photons do not contribute to the recorded hologram.

Main Results:

• Achieved sharp and clear imaging in microfluidic channels containing flowing turbid media.
• Demonstrated the capability to visualize pure phase objects, such as biological cells.
• Showcased the effectiveness of digital holography where other microscopic techniques failed.

Conclusions:

• Digital holography provides a robust solution for high-resolution imaging in challenging microfluidic environments.
• The Doppler frequency shift is key to enabling clear imaging by excluding scattered light.
• This technique significantly advances the potential for in-situ analysis of biological samples in microfluidics.