Submicron-precision particle characterization is crucial for counting, sizing and identifying a variety of biological particles, such as bacteria and apoptotic bodies. Microfluidic impedance cytometry has been attractive in current research...

Cellular mechanical phenotypes in connection to physiological and pathological states of cells have become a promising intrinsic biomarker for label-free cell analysis in various biological research and medical diagnostics. In this work, we present a microfluidic system capable of high-throughput cellular mechanical phenotyping based on a rapid single-cell hydrodynamic stretching in a continuous viscoelastic fluid flow. Randomly introduced single cells are first aligned into a single streamline in viscoelastic fluids before being guided to a flow splitting junction for consistent hydrodynamic stretching. The arrival of individual cells prior to the flow splitting junction can be detected by an electrical sensing unit, which produces a triggering signal to activate a high-speed camera for on-demand imaging of the cell motion and deformation through the flow splitting junction. Cellular mechanical phenotypes, including cell size and cell deformability, are extracted from the analysis of these captured single-cell images. We have evaluated the sensitivity of the developed microfluidic mechanical phenotyping system by measuring the synthesized hydrogel microbeads with known Young's modulus. With this microfluidic cellular mechanical phenotyping system, we have revealed the statistical difference in the deformability of microfilament disrupted, normal, and fixed NIH 3T3 fibroblast cells. Furthermore, with the implementation of a machine-learning-based classification of MCF-10A and MDA-MB-231 mixtures, our label-free cellular phenotyping system has achieved a comparable cell analysis accuracy (0.9:1, 5.03:1) with respect to the fluorescence-based flow cytometry results (0.97:1, 5.33:1). The presented microfluidic mechanical phenotyping technique will open new avenues for high-throughput and label-free single-cell analysis in diverse biomedical applications.

In this work, we demonstrate a sheathless acoustic fluorescence activated cell sorting (aFACS) system by combining elasto-inertial cell focusing and highly focused traveling surface acoustic wave (FTSAW) to sort cells with high recovery rate, purity, and cell viability. The microfluidic sorting device utilizes elasto-inertial particle focusing to align cells in a single file for improving sorting accuracy and efficiency without sample dilution. Our sorting device can effectively focus 1 μm particles which represents the general minimum size for a majority of cell sorting applications. Upon the fluorescence interrogation at the single cell level, individual cells are deflected to the target outlet by a ∼50 μm wide highly focused acoustic field. We have applied our aFACS to sort three different cell lines (i.e., MCF-7, MDA-231, and human-induced pluripotent stem-cell-derived cardiomyocytes; hiPSC-CMs) at ∼kHz with a sorting purity and recovery rate both of about 90%. A further comparison demonstrates that the cell viability drops by 35–45% using a commercial FACS machine, while the cell viability only drops by 3–4% using our aFACS system. The developed aFACS system provides a benchtop solution for rapid, highly accurate single cell level sorting with high cell viability, in particular for sensitive cell types.

Cell viability is a physiological status in connection to cell membrane integrity and cytoplasmic topography, which is profoundly important for fundamental biological research and practical biomedical applications. A conventional method...

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