Structured illumination flowmetry

In this study, we establish the concept of structured illumination flowmetry (SIF) through comprehensive numerical simulations. SIF can capture two-dimensional (2D) flow velocity fields from a single snapshot image of the emission pattern from luminescent probes, using the applied excitation field pattern as a reference. By eliminating the need for any beam or sample scan, SIF has the potential to significantly accelerate the data acquisition process required for velocity field imaging. Furthermore, with excitation patterns applied at different depths, three-dimensional (3D) flow imaging can be achieved. We propose lanthanide-based upconversion nanoparticles (UCNPs), particularly those capable of both absorbing and emitting within the highly biocompatible and transparent NIR-II window (1000–1700 nm), as promising probe candidates for implementing SIF. This concept holds significant potential to pave the way for rapid, three-dimensional (3D) blood flow imaging at sufficient speeds for real-time monitoring of hemodynamic events in the brain.