Robotic cell manipulation with optical tweezers for biomechanical characterization

In this paper, we demonstrate the effectiveness of robotic cell stretching with optical tweezers for biomechanical characterization. Optical traps serve as end-effectors to manipulate micro-beads attached to the cell surface. The dynamics of the cell-bead mixture during cell stretching is investigated for the first time. Based on our previous work, cell stiffness is extracted and biomechanical properties of cells can be characterized. Our study shows that the modeling results agree with the experimental data. Further, the area compressibility moduli of two types of cells, human embryonic stem cells (hESC) and hESC-derived cardiomyocytes (hESC-CM), are characterized. The results indicate that undifferentiated stem cells are much softer than differentiated ones, which provides an important insight into the cell mechanics during hESC differentiation. In summary, this paper successfully demonstrates that the robot-tweezer system can manipulate biological cells effectively to characterize biomechanical properties of living cells.