Mechanical Force Characterization of Living Cells based on Needle Deformation

The mechanical properties of cells play an important role in cell development and function. Therefore, measurement of cell mechanical properties is a fundamental and essential tool for cell research. In this article, a novel method to estimate the force exerted on a living cell is proposed based on glass needle deformation, which does not require additional physical sensors compared with other force-sensing methods. The three-dimensional (3D) spatial state of the needle is reconstructed, and the parameters of needle deflection are obtained based on a multi-focus image fusion algorithm. The average reconstruction error of this algorithm is 0.94 µm. Based on the deformation of the needle, a mechanical model of needle deformation is established, and the model is calibrated using a constructed calibration system. At the range of 0–200 µN, the highest resolution is 0.002 µN and the lowest resolution is 5.3 µN. The proposed method can be used to estimate the force exerted by a needle on the surface of a living cell.