1Department of Mechanical Engineering, PVP Siddhartha Institute of Technology, Kanuru, Vijayawada, A.P., India. E-mail: chepuri_srao@yahoo.co.in
2Department of Mechanical Engineering, College of Engineering, Sri Venkateswara University, Tirupati, 517502, A.P., India. E-mail: ce_reddy@yahoo.com
The smallest functional unit of all living organisms is the individual cell. The properties like young's modulus, Stress relaxation modulus and creep compliance of living cells play a key role in determining cell shape and changes during essential functions such as contraction, crawling and migration. Human platelets are relatively small cells, which play an important role in blood clotting and wound healing. In the bloodstream they are in their resting state, exhibiting a discoid shape. In this paper, an attempt has been made to extract elastic properties such as Elastic modulus and visco elastic (time dependant) characteristics like Stress relaxation modulus and creep compliance of soft living cells (human platelets) by finite element modeling of nanoindentation using a spherical indenter. Simulation has been carried out with the elastic modulus available from the literature as input in which an Atomic Force Microscope is used to indent the human platelets. The elastic and visco elastic properties calculated with the data obtained by finite element simulation are compared with the analytical results and a good agreement is found between the two. Indentation has been done to analyze the time dependent deformation of the cells as a function of stress, strain and with in the 10% of thickness of the sample to avoid substrate influence.
Soft living cells, FEM, Nanoindentation, Stress Relaxation, Creep Compliance
