Elliptocyte detection technology based on super-resolution algorithms for a lensless imaging system

Abstract

As typical poikilocytes, elliptocytes can indicate underlying diseases and are an important additional diagnostic parameter. The current method is to use a microscope for manual analysis of blood smears, which is non-automatic, time-consuming and requires skilled technicians. Lab-on-a-chip technology using a lensless imaging system provides a better solution. However, diffraction effects and low resolution are the two main problems faced by lensless imaging systems. In this paper, Fresnel diffraction at a straight edge is used to analyse the relationship between the red blood cell edge and diffraction rings. First, the diffraction characteristics of red blood cell edges are given. Next, the measurement accuracy is improved. The super-resolution algorithm proposed in this paper can make the measurement accuracy reach at least 1% of the pixel size, which can meet the needs of elliptocyte detection. Then, the complete elliptocyte detection algorithm is given. Finally, by analysing the diffraction characteristics of a typical elliptocyte in detail, a very good match with the elliptocyte images is achieved under the microscope. This proves that the detection technology is effective.

Z-axis displacement measurement model of quasi-spherical cells based on microfluidics under lensless imaging

“…In particular, in most holographic reconstruction technologies, the image acquisition relies on a multi-frame super-resolution algorithm, which is difficult to acquire the images of a moving object. The technique of obtaining cell characteristics based on diffraction fringes can already achieve static cell detection [21][22][23][24][25]. By using compatible devices to measure Z-axis displacement of cells, it can be further realized that this technique is suitable for the cell detection based on microfluidic chips.…”

“…The wavelength of light source is usually several hundreds of nanometers. According to diffraction theory, the spectral line width of the diffraction pattern of a cell is larger than the diameter of the cell, so the diffraction pattern is the result of the multi-position diffraction superposition [21,25]. Because the diffraction edge of the quasi-spherical cell is not a perfect circle, there will be different phases when different positions are superimposed.…”

“…The development of the lensless imaging system based LOC technology makes it possible to achieve the quasispherical cell size measurement for POCT [3,[19][20][21][22][23][24]. The conceptual structure of a typical lensless imaging system based on microfluidics is shown in figure 1.…”

“…How to use the lensless imaging system to obtain the information about these detected cells is a key technology and a research hotspot in recent years. The existing lensless imaging technologies for the cell detection mainly include two types: one is the lensless microscope technology based on holographic reconstruction [3,19,20]; the other is the cytometry technology based on diffraction fringes to obtain cell characteristics [21][22][23][24][25]. These two types of technologies have technical difficulties when facing the lensless imaging of cells in microfluidics.…”

“…The cytometer technology based on diffraction fringes to acquire cell characteristics only requires a monochromatic light source [22][23][24]. If a monochromatic parallel light source is used to measure the cell size, one parameter can be reduced and the model can be simplified [21,25]. Since the imaging system has no lens, the resolution of its image is very low.…”