POCYTON · A Novel Detection Scheme to Enable Point of Care Flow Cytometry

In PoCyton, a revolutionary concept for the detection zone of a flow cytometer is proposed. Flow cytometers are fluorescence-based cell counters and as such are indispensable instruments in clinical and biomedical research. Over the last four decades, despite gradual technical improvements in the constituent components, the detection principle has virtually remained unchanged. Fluorescently tagged cells in suspension are made to flow through a narrow focal excitation area and then detected via the fluorescent pulse emitted by them. The narrow focus imposes restrictions on the flow rate and, as a consequence, on feasible sample volumes. Moreover, the alignment of cell-flow, excitation, and detection requires extreme precision. To this end, expensive, bulky components have to be used, preventing substantial miniaturization of flow cytometry. In PoCyton, the detection zone will be enlarged and superimposed with a pseudo-random pattern leading to a temporally extended, distinctly coded signal recorded for each fluorescing cell. In analogy to spread-signal methods, each cell will be reconstructed from the coded signal by correlation techniques. While the precision in spatial cell discrimination outperforms that of conventional flow cytometry only slightly, the signal-to-noise ratio is enhanced significantly, resulting in a notable improvement in sensitivity. In addition, the enlargement of the detection zone dramatically mitigates alignment issues. In PoCyton, various implementations and extensions towards multi-colour flow cytometry will be studied experimentally to demonstrate their high sample-throughput and miniaturization (lab-on-a-chip) potential. Ultimately, a wider range of flow cytometry methods will thus be made available for routine use in clinical laboratories and medical point-of-care diagnosis, e.g., for cancer treatment. PoCyton is a multi-disciplinary project primarily involving expertise in optics, microfluidics, micro-systems, and signal processing.