Flow Cytometric Mechano-Indexing Reveals Time-Transition of Bioparticles

We present a mechano-indexing system based an ultrasound microscope, which enables flow cytometric measurement of mechanical characteristics of bioparticles such as hydrogel-beads, cells, and spheroids. Unlike the conventional mechanical characterization methods based on a contact manner such as mechanical probing with high-resolution but low-throughput, our non-contact method allows to measure the ultrasound waves relating mechanical characteristics of flowed bioparticles in a glass- capillary-based microchannel with exceedingly high-throughput. By utilizing the constructed system, we demonstrated the proposed flow cytometric mechano-indexing using glass microbeads, hydrogel microbeads, Euglena gracilis which is a microalga, and cell spheroid of mesenchymal stem cell (MSC spheroid). Especially, the experimental results of MSC spheroid showed that time-transition of their mechanical characteristics with respect to the culture days.