This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.Red blood cells (RBCs) perform essential functions in human body, such as gas exchange between
blood and tissues, thanks to their ability to deform and flow in the microvascular network. The high RBC
deformability is mainly due to the viscoelastic properties of the cell membrane. Since an impaired RBC
deformability could be found in some diseases, such as malaria, sickle cell anemia, diabetes and hereditary
disorders, there is the need to provide further insight into measurement of RBC deformability in a
physiologically-relevant flow field. Here, we report on an imaging-based in vitro systematic microfluidic
investigation of RBCs flowing either in microcapillaries or in a microcirculation-mimicking device
containing a network of microchannels of diameter comparable to cell size. RBC membrane shear elastic
modulus and surface viscosity have been investigated by using diverging channels, while RBC time recovery
constant have been measured in start-up experiments. Moreover, RBC volume and surface area have been
measured in microcapillary flow. The comprehension of the single cell behavior led to the analysis of the
RBC flow-induced clustering. Overall, our results provide a novel technique to estimate RBC deformability,
that can be used for the analysis of pathological RBCs, for which reliable quantitative methods are still
lacking