Holographic processing pipeline for tomographic flow cytometry

We report on a smart solution to obtain Tomographic Phase Microscopy (TPM) of samples in microfluidic environment, by exploiting their tumbling while flowing in a microchip. This method permits to observe full 360° of rotating cells, this avoiding the limitation in the accuracy of tomograms, and no mechanical contact neither holographic optical tweezers are needed to rotate the sample. Moreover, it is suitable for application in flowing conditions with high-throughput performances. In fact, it allows to monitor a large number of cells, the only limit being the frame rate of the camera used to acquire data, and to analyze in principle each single cell with high resolution, regardless of its shape or symmetry. This would allow real microfluidic biomedical applications on a large scale. Summarizing, the whole process is accomplished following the subsequent steps: (i) holograms acquisition of cells flowing in microfluidic channels; (ii) 3D tracking and realignment by using either biolens effect or particular symmetries (depending on the object's structure); (iii) connection between rotation angles and phase maps; (iv) complete 3D image retrieving, displaying the inner structure of the object (i.e. tomography).