Experimental Shear Property Characterization of Agarose Hydrogel and Polydimethylsiloxane (PDMS)

Soft materials exhibit a unique blend of properties resembling either a solid or liquid. Hydrogels and polydimethylsiloxane (PDMS) are a few examples of soft materials. These materials exhibit viscoelastic properties which makes them difficult to determine the mechanical properties through conventional means. In addition, the material properties are highly dependent on their concentration ratios—wt./wt. for PDMS and wt./solvent volume for agarose hydrogel. A new in-plane shear test method, which incorporates 3D printed parts and Digital Image Correlation (DIC), was developed and updated to fully quantify the mechanical shear properties of agarose hydrogels at multiple concentrations (4.0, 2.5, 1.5, and 0.5% wt./vol.) and PDMS at multiple mixture ratios (10:1, 20:1, and 30:1 wt./wt.). The 3D printed parts were used as loading fixtures to ensure the appropriate grip on these soft materials. Verification of the agarose testing was conducted through the use of a plate-plate shear rheometer.