Mechanical Characterization of Mouse Oocytes
Xinyu Liu (McGill University), Jiayi Shi (Northeastern University), Yu Sun (University of Toronto), Kai-Tak Wan (Northeastern University)
Mechanics and Physics of Biological Cells
Wed 9:00 - 10:30
Barus-Holley 141
To perform intracytoplasmic sperm injection (ICSI), a mouse oocyte is contained in a PDMS fixture. A micropipette indents on the cell wall that undergoes large deformation, followed by puncture of the zona pellucida and delivery of the sperm. A force sensor measures the mechanical force and the indentation displacement simultaneously, while a computer vision tracking algorithm tracks the real time deformed cell profile. A stress-relaxation loading process yields the viscoelastic properties of young and aged oocytes. To construct a reasonable solid-mechanics to extract materials parameters, three distinct models are constructed treating the cell as (i) an isotropic linear elastic sphere according to the Hertz contact theory, (ii) a hollow spherical shell where the bending and stretching are present, (iii) a liquid filled spherical shell with a nonzero internal pressure. The three methods yield vastly different elastic moduli from the same -displacement response, and method (iii) fits best ti the measurement and yields the most reasonable materials properties consistent with the literature.