Characterizing the Mechanical and Visoelastic Properties of Sodium Alginate

A crucial part of tissue engineering lies in understanding and characterizing the mechanical and viscoelastic properties of various types of biomaterials. Understanding these properties allows better biomaterials to be produced with characteristics more similar to those of the human body and with better biocompatability. In this study, sodium alginate was chemically crosslinked with calcium chloride and subsequently tested for it's instantaneous Elastic Modulus, instantaneous Shear Modulus, and equivalent viscosity using indentation testing methods consisting of a stress-relaxation test and nonlinear curve-fitting analysis. Two and three millimeter indentation tests were performed using a low-cost and portable device built in-lab that resulted in five viscoelastic parameters of G_Inf, G_1, G_2, Tau_1, and Tau_2. These values resulted in an average instantaneous Elastic Modulus of 5044 Pascals, an average instantaneous Shear Modulus of 1681 Pascals, and an equivalent viscosity of 4710 Pascal-seconds for an indentation depth of 2 millimeters. Moreover, these values also resulted in an average instantaneous Elastic Modulus of 8553 Pascals, an average instantaneous Shear Modulus of 2851 Pascals, and an equivalent viscosity of 7317 Pascal-seconds for an indentation depth of 3 millimeters. Overall, these findings suggest an increase in viscoelastic and mechanical properties relative to their displacement distance. Understanding the viscoelastic and mechanical behavior of these biomaterials holds clinical significance for designing better implantable prostheses, drug-deliverable medical devices, and wound healing scaffolds.