High-throughput microfluidic particle velocimetry using optical time-stretch microscopy

We report the velocity measurement of microscopic particles flowing at ultrahigh speed with optofluidic time-stretch microscopy at high throughput. This is a study of using optical time-stretch microcopy as a tool for particle velocimetry, where we developed a custom algorithm to process the images acquired from the optofluidic platform for the velocity calculation of individual particles. We experimentally determined the actual flow velocities for polystyrene microspheres with different sizes and traveling through the microchannel at a throughput of similar to 10 000 particles/s. We also examined microfluidic channels with different aspect ratios (depth-to-width) for particle velocimetry. The result indicates a measurable flow velocity up to 2.51 m/s. Our method provides a promising tool for label-free and high-throughput particle velocimetry at high velocity magnitudes.