Simultaneous and Contactless Characterization of the Young's and Shear Moduli of Gelatin-Based Hydrogels

Background Biocompatible hydrogels have a wide range of applications including tissue engineering and biofabrication. Since the cell and tissue behavior is greatly influenced by the mechanical properties of their environment, identifying the mechanical characteristics of these soft materials and their characterization methods are critical to understanding the dynamic behavior of the materials being employed in various applications. Objective This research aims to investigate a non-contact method that simultaneously measures the Young's and shear moduli of soft matter such as translucent elastic hydrogels. Methods The modal characteristics of gelatin-based hydrogel column are extracted from videos by utilizing phase-based motion estimation. The fundamental flexural and torsional resonance frequencies are identified by estimating the corresponding mode shapes via motion magnification and utilized to extract the moduli using analytical model of vertical cantilever beam considering self-weight. To verify the principles of the proposed approach, a finite element model is formulated and its response characteristics are compared with the experimentally obtained values. Results Numerical and experimental investigation results on gelatin samples with various concentrations verify that the proposed method reliably identifies the Young's and shear moduli of the soft matter without any influences such as mass loading effects stemming from contact-based measurements, which is critical for the measurement of soft materials. Conclusions Overall, the results of this study show promising potential of implementing the proposed approach for characterizing mechanical properties of soft matter in various fields such as food industry, cell biology, and engineering applications including soft robotics, wearable sensors, tissue engineering and biofabrication.

Automated summary

This research proposes a non-contact method to simultaneously measure the Young's and shear moduli of soft matter such as translucent elastic hydrogels. The modal characteristics of the hydrogel samples are extracted and the mechanical properties are calculated using analytical models. Numerical and experimental results demonstrate the reliability of the proposed method.