Friday, October 28, 2011
Hall 1-2 (San Jose Convention Center)
Agarose is a biopolymer with high water content that exhibits visco/poroelastic properties. Being an attractive biomaterial for tissue engineering, the mechanical properties of agarose, such as its elasticity and permeability play an important role in the properties of the engineered tissue. In this study, a dynamic indentation approach was employed using a modified high-frequency Atomic Force Microscope (AFM) to study the poroelastic behavior of agarose. We used a spherical probe tip (Rtip = 12.5µm) with initial indentation δ0 = 3µm and a superimposed oscillatory displacement with amplitude of only δ = 15nm with varying frequency to observe the 4-decade spectrum (f ~ 0.1 to 1000 Hz) response of agarose. For agarose gel concentration at 2 % (dissolved in PBS) the magnitude and phase of dynamic stiffness increased with loading frequency. The magnitude of the dynamic stiffness was observed to be 0.15 MPa at the oscillation frequency of 0.1Hz while it reached to 0.3 MPa at 1000Hz. The increase in the stiffness magnitude is potentially due to pressurization of the liquid phase of the gel. The phase angle, which is representative of the energy dissipation, observed to be 0 at 0.1Hz and increased monotonically to 20 degrees at 1000Hz. The experimental data will be inputted to the finite element model developed to quantify the poroelastic properties of agarose. In addition, to further investigate the poroelastic properties of agarose, we will test different agarose concentration (2 to 8%) to observe the variations in the frequency-dependent magnitude and phase of the dynamic stiffness.