Due to the working principle of probe indentation, most of the Young’s modulus are measured in the direction normal to cell membranes or substrate planes. The elasticity (Young’s modulus) of various cells such as endothelial cells, leukocytes and fibroblasts has been characterized using AFM 15, 16, 17, 18, 19, 20, 21. AFM has several advantages such as high spatial resolution, and can be operated in aqueous solution that allows live cells be analyzed in their physiological environments. It provides a direct access for researchers to obtain nano-scale topographical and physical information about cells. In addition, viscoelastic response and related physical properties of cells can be observed by monitoring fluorescent nano-beads injected into fibroblast cells 14.Īmong various characterization methods, atomic force microscopy (AFM) has been broadly utilized. Also, physical characteristics such as elastic behaviour, viscous response and contractile behaviours of adherent fibroblast cells can be measured using microplate manipulation and elastic substrate methods 12, 13. Optical stretcher is exploited to measure elasticity of biological cells without mechanical contact 11. In another research, shear modulus of human erythrocyte membrane can be estimated using optical tweezers 10. For example, whole-cell elasticity in suspension can be measured by micropipette aspiration 7, 8, 9. Consequently, measurement of cell elasticity is an essential task in biomedical research.Ī number of studies have attempted to characterize elastic properties such as Young’s modulus or shear modulus through whole-cell or spatially confined (point on a cell) approaches. In addition, different subpopulation cells can be rapidly sorted by their elasticity 6. Therefore, by investigating physical properties of cells, malignant and non-malignant cells can be reliably distinguished while normal and cancerous cell morphologies are similar 5. For instance, several studies have shown a reduction in cell elasticity with increasing metastatic efficiency in human cancer cell lines 1, 2, 3, 4. Elasticity is one of the most important physical properties, but not well studied due to technical limitations. Functions of cells are determined by their structures, and the structural organization of cells can be characterized by various physical properties. To understand interactions between cells and their microenvironments, investigation on physical properties of cells becomes essential. Consequently, the developed microfluidic device provides a powerful tool to study physical properties of cells for fundamental biophysics and biomedical researches.Ĭellular microenvironment plays a critical role in regulating biological activities under various normal and pathological conditions. Furthermore, the in-plane elasticity can be monitored during the cell transformation after the growth factor stimulation.

The experimental results confirm highly anisotropic configuration and material properties of cells. For comparison, elasticity measurement on the cells by atomic force microscopy (AFM) is also performed. In addition, the cells are treated with a growth factor to simulate lung fibrosis to study the effects of cell transformation on the elasticity variation. In the experiments, human embryonic lung fibroblast (MRC-5) cells are cultured and analyzed to estimate the in-plane elasticity. When cells are cultured on top of the membrane, flexural rigidity of the composite membrane increases and further changes the output electrical signals. The sensor converts pressure-induced deformation of a flexible membrane to electrical signals.

This paper reports time-lapsed measurement of live cell layer in-plane elasticity using a pressure sensor embedded microfluidic device. Capability of continuous monitoring elasticity of live cell layers during a period is highly desired to investigate cell property variation during various transformations under normal or disease states. In various physiological activities, cells experience stresses along their in-plane direction when facing substrate deformation.

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