Spatially modulated emission for point-of-care flow cytometer

Virtually all commercial flow cytometers rely on optical interaction with the bio-particles for characterization, through fluorescence, scattering, or absorption processes. And all use the same basic optical configuration, namely, intense illumination of the bio-particle as it speeds through a highly localized spot, which generally involves a complex arrangement of optics (e.g., lenses, mirrors, apertures, and filters). This highly focused beam of light is required to achieve usable sensitivity since the signal is proportional to the photon flux density. While such instruments are extensively used in research and clinical laboratories, they do not meet the challenging practical requirements for point-of-care (POC) diagnostics in resource-limited settings, such as CD4 monitoring which is required for proper treatment of HIV infected persons. In this presentation we will describe and illustrate a fundamentally new design of the optical detection system that delivers high effective sensitivity (i.e., high signal-to-noise discrimination) without complex optics or bulky, expensive light sources to enable a flow cytometer that combines high performance, robustness, compactness, low cost, and ease of use. The enabling innovation is termed “spatially modulated emission/excitation” and involves relative movement between a fluorescing bio-particle and a patterned environment... The technology will be demonstrated with characterization of individual fluorescent beads (diameters: 6 microns, 2 microns and 0.6 micron), detection of tagged CD4 cells, and CD4 counting in whole blood.