Micromechanics and Structure of Soft and Biological Materials

This work addresses the microrheology of soft and biological materials such as poly(ethylene)oxide solutions, type I collagen gels and endothelial cells using a novel oscillating optical tweezers technique.This advantageous technique is based on grabbing probe particles suspended in the media of interest with a tightly focused laser beam, measuring displacements and phase shifts of the particle s motion from which to calculate the viscoelastic properties of homogeneous and inhomogeneous materials as the function of frequency and time. The validation of the optical tweezers microrheology is given in comparison between passive and active, forced oscillation approach. The local response of collagen gels was probed in order to characterize their viscoelastic and structural composition. This work expands the knowledge of these promising biological materials for use in tissue engineering as well as for opportunities in diagnostics and comparisons between normal and degenerated tissues in cancer research.The optical tweezers technique will be extended to use on endothelial cells to test the applicability of this probe as a non-invasive, effective rheometer in biomedical research.