Localized cell stiffness measurement using axial movement of an optically trapped microparticle.

A simple optical tweezers design is proposed to manipulate particles in the axial direction and estimate particle position with nanometer sensitivity. Balb3T3 cell is probed using two different-sized particles, and the localized cell stiffness is evaluated using Hertz model. A series of experiments are performed to obtain the necessary parameters for the cell stiffness computation: particle displacement, trapping stiffness, force exertion, and cell deformation. The computed cell stiffness measurements are 17 and 40 Pa using 4 μm- and 2 μm-sized particles, respectively. Results suggest that the proposed optical tweezers scheme can measure the stiffness of a particular cell locale using Hertz model, offering insights about how cells respond to outside mechanical stimulus.