Light scattering by an erythrocyte based on discrete sources method Shape and refractive index influence

Keywords: Red blood cell Light scattering Discrete sources method a b s t r a c t An efficient method for the fast detection of properties of a single erythrocyte from its scattering characteristics is needed in practice. To develop such a method a detailed investigation of the light scattering properties of the erythrocyte and their dependence on its shape and refractive index is of great interest. In this paper the influence of the real erythrocyte's shape with deep concavities and refractive index on the scattering characteristics is analyzed based on an updated scheme of the discrete sources method. Realistic shape models of an erythrocyte, calculated from minima of membrane potential energy are considered. The numerical scheme of discrete sources method has been adjusted for shape profiles given numerically. An improved algorithm allows increasing of an accuracy of calculations. Light scattering by human blood cells is of great interest in different practical applications, due to the important role they play in our body. In particular, the measurement of light scattering by blood cells is a suitable method for investigation of blood cells properties: shape, size and refractive index, which can serve as markers for different human diseases [1]. The investigation of properties of a red blood cell (erythrocyte) and their connection to the scattered light is in focus of interest for years now, especially in modeling applications [2–4]. The reason is that change of erythrocyte's physical properties, like shape or hemoglobin contain can be used for detection of diseases. The problem of reconstruction of erythrocyte's properties from its light scattering characteristics is an inverse scattering problem [5]. In nature the shape of a human erythrocyte can vary in from nearly spherical through biconcave to toroidal ones and the refractive index of the cell depends on its hemoglobin concentration. These aspects complicate modeling and make the inverse problem hard to solve [6]. On one hand, the modeling of light scattering by an erythrocyte should not be complicated as the particle demonstrates no internal structure, on the other hand its large size (typically in the range of 6–10 mm) and complicated shape of healthy erythrocyte (biconcave discoid) causes problems which can not be overcame by many modeling methods. During the recent years different simulation methods have been applied to model light scattering by erythrocyte: finite difference time domain (FDTD) [7], discrete dipole approximation (DDA) [8], multipole multiple technique (MMP), T-matrix method [9], …