Particles small angle forward-scattered light measurement based on photovoltaic cell microflow cytometer

A method is proposed for detecting microparticles in a microflow cytometer by means of small angle forward-scattered light measurements. The proposed cytometer comprises a commercial photovoltaic cell, an adjustable power laser module, and a PDMS microfluidic chip. The detection performance of the proposed device is evaluated using particles with dimensions of 5, 8, 10, and 15 μm, respectively, given forward-light scattering angles of 5 and 8° and laser powers ranging from 15-25 mW. It is shown that for a constant laser power and particle size, the S/N of the detected light signal increases with a reducing forward-scattering angle. Moreover, for a constant forward-scattering angle and particle size, the S/N increases with an increasing laser power. The intensity of the forward-scattered light signal is found to vary linearly with the particle size and has a correlation coefficient of R² = 0.967, 0.967, and 0.963 given laser powers of 15, 20, and 25 mW, respectively, and a forward-scattering angle of 5°. Moreover, the CV of the forward-scattered light intensity is found to lie within the range of 20-30% for both forward-scattering angles. Overall, the present results suggest that the proposed device has significant potential for detection applications in the medical, environmental monitoring, and biological science fields.