Optofluidic characterization of marine algae using a microflow cytometer.

Area of Science:

• Marine Biology
• Environmental Science
• Biotechnology

Background:

• Phytoplankton populations are key indicators of environmental changes, including global warming, pollution, and altered ocean currents.
• Accurate characterization of phytoplankton is essential for monitoring ocean health and understanding ecological shifts.

Purpose of the Study:

• To design and fabricate a microflow cytometer for the detailed characterization of phytoplankton.
• To investigate the optical and fluorescence properties of key marine phytoplankton species.

Main Methods:

• A microfluidic channel with chevron-shaped grooves was used for hydrodynamic focusing of phytoplankton samples.
• Intrinsically fluorescent phytoplankton were analyzed using lasers tuned to chlorophyll and phycoerythrin absorbance wavelengths.
• Optical and side scatter, fluorescence, and light scatter signals were collected and analyzed using photomultiplier tubes and optical filters.

Main Results:

• The microflow cytometer successfully measured optical and side scatter properties of Karenia b., Synechococcus sp., Pseudo-Nitzchia, and Alexandrium.
• The study investigated the impact of sheath-to-sample flow-rate ratios on signal heterogeneity.
• Reducing sample flow rate enhanced stream focus and reduced signal variability, improving measurement accuracy.

Conclusions:

• The developed microflow cytometer is a viable tool for characterizing phytoplankton populations.
• This technology can aid in monitoring the ecological impacts of global warming and pollution on marine environments.
• Optimized flow conditions improve the precision of phytoplankton analysis using microfluidic devices.