Quantification of algal cell concentration based on optical coherence tomography

Abstract

Accurate measurements of the algal cell concentration are critical in microalgae culturing and ecological monitoring. Here, we propose a non-contact method based on scattering coefficient intensity analysis using optical coherence tomography (OCT) to quantitatively assess green algal concentrations through scattering coefficient analysis of their depth distribution. To evaluate the feasibility of the method, the B-scans of green algae suspensions at different dilution levels in the centrifuge tubes were collected by OCT at the same lateral position. Then the amplitude information of each frame of the complex OCT sequence was extracted, and the scattering coefficient was calculated to preclude the effect of nonuniform illumination at different depth when collecting images in the OCT system. The scattering coefficients map of the green algae was performed digital image processing, in order to obtain the numbers of algae cells within a fixed region. By analyzing the map of scattering coefficients, the concentration of green algae can be derived and the distribution of green algae cells can be further studied. The results show that OCT scattering coefficient-based method can quantitatively assess different concentrations of green algae suspensions under non-contact conditions, and the scattering coefficient images can provide the depth distribution of green algae cells. This method provides an in situ, accurate and non-invasive tool for monitoring the growth of green algae in water bodies and can effectively monitor the growth of green algae and the health status of water bodies.