Towards multiphysics 4D particle tracking in microchannels with high-speed light-field microscopy

This work presents recent progress toward high-resolution, single-camera 4D particle tracking in microfluidic environments using a custom-built Fourier light-field microscope. The system captures seven angular views on a single high-speed sensor and reconstructs volumetric particle motion without requiring multiple synchronized cameras. Building on previous work that demonstrated particle localization accuracy below 0.3 micrometers, the present study extends the measurement depth from about 50 micrometers to more than 160 micrometers by using experimentally registered defocused point spread functions and neural-network-based particle detection. The microscope maintains a 370 micrometer wide field of view and records at 1300 frames per second streamed directly to disk. The improved framework is demonstrated in several challenging microfluidic configurations, including pillar wakes, junction flows, and a backward-facing step geometry from the first defocused particle tracking challenge. These results show that high-speed Fourier light-field microscopy can provide compact, single-camera access to time-resolved 3D flow measurements in optically constrained microchannels. Future developments will extend the method beyond seeded-particle velocimetry toward multiphysics measurements involving near-wall transport, scalar fields, biofilms, active microswimmers, and intensity-based reconstructions.