Real-time deformability cytometry (RT-DC) is a novel high-throughput method for the mechanical characterization of single cells that has recently been developed in our lab [3, 4, 5]. Based on the hydrodynamic deformation of cells translocating through a microfluidic channel in a contact-free manner, RT-DC is able to analyze more than 100 cells per second in real-time.
The main working principle of RT-DC is shown in the figure. Within a few milliseconds upon entry of a cell into the channel, the cell shape reaches a steady state. For each cell, several parameters can be recorded in real-time which can be visualized and gated in a post-processing step using our in-house software ShapeOut. Analytical and numerical models developed in our lab also permit the derivation of material properties such as the Young’s modulus [1, 2]. The technique is now being applied in more than 50 collaborations [6, 7, 8].
Furthermore, we have recently developed an RT-DC setup with fluorescence detection (RT-FDC). Now it is possible to not only detect the mechanical phenotype of each individual cell but also to simultaneously gather its fluorescence intensity in up to three channels in a manner similar to a conventional flow cytometer . This direct correlation of mechanical with fluorescence data based on dyes, fluorescent reporter proteins or surface markers will lead to a more comprehensive validation of cell mechanics as a label-free marker.
RT-DC and RT-FDC are available as commercial products from the spin-off company ZELLMECHANIK DRESDEN GmbH.
 A. Mietke, O. Otto, S. Girardo, P. Rosendahl, A. Taubenberger, S. Golfier, E. Ulbricht, S. Aland, J. Guck, and E. Fischer-Friedrich, “Extracting cell stiffness from real-time deformability cytometry: theory and experiment,” Biophysical Journal, vol. 109, iss. 10, p. 2023–2036, 2015.
 M. Mokbel, D. Mokbel, A. Mietke, N. Träber, S. Girardo, O. Otto, J. Guck, and S. Aland, “Numerical simulation of real-time deformability cytometry to extract cell mechanical properties,” Acs biomaterials science & engineering, 2017.
 O. Otto, P. Rosendahl, A. Mietke, S. Golfier, C. Herold, D. Klaue, S. Girardo, S. Pagliara, A. Ekpenyong, A. Jacobi, M. Wobus, N. Töpfner, U. F. Keyser, J. Mansfeld, E. Fischer-Friedrich, and J. Guck, “Real-time deformability cytometry: on-the-fly cell mechanical phenotyping,” Nature Methods, vol. 12, iss. 3, p. 199–202, 2015.
 M. Herbig, M. Kräter, K. Plak, P. Müller, J. Guck, and O. Otto, “Real-time deformability cytometry: label-free functional characterization of cells,” in Flow cytometry protocols, Springer New York, 2017, p. 347–369.
 M. Urbanska, P. Rosendahl, M. Kräter, and J. Guck, “High-throughput single-cell mechanical phenotyping with real-time deformability cytometry,” in Methods in cell biology, Elsevier, 2018, p. 175–198.
 N. Toepfner, C. Herold, O. Otto, P. Rosendahl, A. Jacobi, M. Kräter, J. Stächele, L. Menschner, M. Herbig, L. Ciuffreda, L. Ranford-Cartwright, M. Grzybek, Ü. Coskun, E. Reithuber, G. Garriss, P. Mellroth, B. Henriques-Normark, N. Tregay, M. Suttorp, M. Bornhäuser, E. R. Chilvers, R. Berner, and J. Guck, “Detection of human disease conditions by single-cell morpho-rheological phenotyping of blood,” eLife, vol. 7, 2018.
 M. Kräter, J. Sapudom, N. Bilz, T. Pompe, J. Guck, and C. Claus, “Alterations in cell mechanics by actin cytoskeletal changes correlate with strain-specific rubella virus phenotypes for cell migration and induction of apoptosis,” Cells, vol. 7, iss. 9, p. 136, 2018.
 M. Urbanska, M. Winzi, K. Neumann, S. Abuhattum, P. Rosendahl, P. Müller, A. Taubenberger, K. Anastassiadis, and J. Guck, “Single-cell mechanical phenotype is an intrinsic marker of reprogramming and differentiation along the mouse neural lineage,” Development, vol. 144, iss. 23, p. 4313–4321, 2017.
 P. Rosendahl, K. Plak, A. Jacobi, M. Kraeter, N. Toepfner, O. Otto, C. Herold, M. Winzi, M. Herbig, Y. Ge, S. Girardo, K. Wagner, B. Baum, and J. Guck, “Real-time fluorescence and deformability cytometry,” Nature methods, vol. 15, iss. 5, p. 355–358, 2018.