On-Chip Particle Differentiation Utilizing Forward Scattered Light and Fluorescence Light With Passive Focusing

In this paper, a microflow cytometer for particles/cells passive focusing, fluorescence detection, and sizing is demonstrated with a convergent geometry of 50 μm detection gate channel and a pair of external optic fibers on poly-dimethylsiloxane (PDMS) microchip. A laser (635 nm) is used for fluorescent excitation. The amplitudes of the backward fluorescence signal and forward scattered light signal indicate the corresponding fluorescent intensity and size of the detected fluorescent particles and labeled white blood cells, respectively. In the experiment, the uniform fluorescent light intensity was measured by focusing the fluorescent particles in a 200×50×30μm detection gate channel. However, the emitted fluorescence and forward scattered light intensity of different size particles/cells are also measured simultaneously by external optic fibers.