Single-camera 3D Lagrangian particle tracking in a microfluidic channel

'Shake-The-Box' (STB) is a widely used Lagrangian tracking method for reconstructing and tracking time-resolved particle fields in 3D. Traditionally, this requires multiple cameras from different angles, which can be costly and complex to align, especially in space-constrained setups. By employing Fourier light-field microscopy (FIMic), a form of single-camera plenoptic imaging, high-resolution 3D flow measurements are achieved with just one high-speed camera, eliminating the need for multiple imagers. This method offers a resolution of approximately 2 μm in 3D, with lateral and depth resolutions within 25% of each other, a first for 3D velocimeters. Particle positions can be resolved to less than the imaging wavelength. The method's effectiveness is demonstrated through flow analysis in a microfluidic device with a cross-junction channel. This technique will not only enhance microfluidic device design and performance understanding but also, due to its high spatial resolution, has the potential to probe the smallest scales of wall-bounded turbulent flows at high Reynolds numbers.