Monitoring CD4 in whole blood with an opto-fluidic detector based on spatially modulated fluorescence emission.

We describe a new optical detection technique, termed "spatially modulated fluorescence emission," that delivers high signal-to-noise discrimination without precision optics to enable a flow cytometer that can combine high performance, robustness, compactness, low cost, and ease of use. The detection technique is demonstrated with measurements of absolute CD4+ and percentage CD4 counts in human blood. Benchmarking against a commonly used commercial instrument for this test yields excellent agreement for both absolute CD4 and percentage CD4.