High-throughput diatom counting method based on lens-free shadow image analysis

Recently, there has been an increase in research on diatoms in a number of fields owing to their unique traits and the variety of species. However, in most of the research, cell counting is performed in the traditional way, using an optical microscope. Due to the diatom's tendency to aggregate into groups and the bias created by the small field of view of the optical microscope, numerous replications are required for accurate characterization of diatoms. In this study, one image obtained by a lens-free shadow imaging platform is used to rapidly and economically characterize diatoms in a high-throughput manner. Furthermore, the accuracy was determined by direct comparison with results of optical microscopy characterization. The calculation of the signal-to-noise- ratio (SNR) and shadow diameter (SD) from the different shadow patterns created by the various morphologies of the diatoms allowed for their characterization. In addition, by analyzing the differences in the diffraction pattern between the living and dead cells, it was possible to count the living diatom cells.