Biaxial stretching of single cells using a compliant micromechanism

Abstract

Abstract Biological cells are exposed to a variety of mechanical stimuli from their environment. Cells convert these mechanical stimuli to specific biochemical signals through a process known as mechanotransduction, which is necessary for proper functioning of cells. Biaxial stretching is one such stimuli observed in tissues such as lung alveoli, pericardium, blood vessels and urinary bladder. To study the effect of biaxial stretching on cell function, or any other mechanotransduction process, it is essential to develop tools capable of manipulating cells in the respective deformation mode. Here, we report the design, fabrication and actuation of a compliant micromechanism for in-plane, biaxial stretching of single cells. Further, we demonstrate biaxial stretching of NIH-3T3 cells (mouse fibroblasts) using this micromechanism. Our device is an amalgam of a gripper mechanism and an auxetic structure, which can be actuated using a mechanical probe. Cells can be stretched equibiaxially or with any non-equibiaxial stretch ratio, by altering the mechanism geometry. The device is made of SU-8 using a two-layer lithography process. Since SU-8 is transparent and biocompatible, we could attach cells to the mechanism, stretch them and continuously image during stretching. Our device could be useful for elucidating the biological response of cells to biaxial stretching and for characterising the anisotropic mechanical properties of single cells.