Identification of refractive index for label-free single cells based on 2D light scattering technology

Two dimensional (2D) light scattering technology is an important part of the single cell analysis, which can recognize the differences of inherent physical properties of biological particles. Based on the label-free static cytometry, collimated light from a laser with a wavelength of 532 nm is coupled into a multimode optical fiber. The fiber localizes and illuminates single static biological particles. Single particles are excited and their scattered light is collected. In this paper, the 2D light scattering patterns are obtained from 4 μm and 6 μm polystyrene microspheres (PS, refractive index, 1.59) and silica microspheres (SiO₂, refractive index, 1.45). The corresponding simulated scattering patterns are obtained by Mie scattering theory. Then, Fourier analysis of the 2D scattering patterns is performed for measuring the refractive index of single particles. The results indicate that the 2D light scattering technique may provide an efficient, low-cost, and easy-to-use approach to the nondestructive identification and classification of cancer cells at the single cell level.