Multifocal Metalens-Assisted Correlation Spectroscopy for Measuring Microfluidic Dynamics

Measuring the dynamics of flowing particles is crucial for various fields, including biophysics, industrial inspection, and environmental monitoring. Here, we present a multifocal metalens for correlation spectroscopy, enabling measuring microfluidic dynamics in a wide measuring range without the need of fluorescence labeling. The metalens here allows implementation of correlation spectroscopy without relying on bulk optical components, such as differential interference contrast prism and Mach–Zehnder (M–Z) interferometers, thereby significantly reducing experimental complexity and enhancing measurement reliability. Employing the appropriate fitting model, we accurately predict the concentration and flow velocity of poly(methyl methacrylate) microspheres and rat’s blood within microfluidic channels. The proposed multifocal metalens-assisted correlation spectroscopy approach provides new avenues for dynamics measurement in microfluidic devices and can be applied in biomedical diagnostics, environmental monitoring, and lab-on-a-chip systems.