Characterization of hydrogel structures using video-based vibration analysis

Investigating the mechanical properties of biological and biocompatible hydrogel materials has recently gained extensive research interest due to their potential applications in various fields including tissue engineering, bio-robotics and sensors. However, estimating the essential structural characteristics such as elastic moduli of hydrogel structures may not be easily identified using conventional contact-based techniques such as accelerometers and strain gauges due to their additional mass loading to the structure and influence on the shape of the hydrogel structure by mechanical contact. Non-contact optical methods such as Laser-Doppler vibrometry may be able to identify the vibration characteristics; yet, the low reflectivity of translucent hydrogel’s surfaces is one of the major challenges in laser-based vibration analysis, and experimentally estimating the mode shape requires significant effort. In this study, we aim to investigate a contactless method to simultaneously identify the Young’s and shear moduli of hydrogel structures by employing video-based vibration analysis. Phase-based motion estimation and magnification are utilized to experimentally determine the resonance frequencies and operational deflection shapes and identify the Young’s and shear moduli of gelatinous hydrogel structures. The experimental results of this study provides promising potential of implementing the proposed approach for applications in areas including advanced manufacturing and soil characteristics identification.