An Innovative Drop Tower System for Quantifying Cavitation in Soft Biomaterials Under Repeated Mechanical Impacts

Background

Soft materials play a key role in biomedical applications due to their high deformability, but they are highly susceptible to damage and degradation under cyclic mechanical loading. The dynamic behavior of biological soft materials, particularly under high strain rates and repeated impacts, has garnered significant research interest related to traumatic injuries; however, these studies remain limited due to experimental challenges.

Objective

This study aims to develop and validate a novel system for non-invasively characterizing the dynamic mechanical responses of soft biomaterials under repeated high-strain-rate impacts and to explore how repeated impacts influence cavitation nucleation thresholds.

Methods

A custom-designed repeated impact tester, combining a conventional drop tower system with custom-built components, was developed. The dynamic characteristics of our novel repeated impact tester were validated through a combination of theoretical modeling and experimental confirmation. Experimental validations were performed using 0.75w/v% agarose gel samples to demonstrate the tester’s capabilities.

Results

Our experimental studies, supported by a theoretical model, demonstrated that our new tester enables precise control and measurement of key dynamic characteristics of mechanical impacts. Using a novel non-optical detection method for identifying cavitation events, we tested 0.75w/v% agarose samples and observed that repeated impacts significantly reduce the critical acceleration required to trigger cavitation.

Conclusions

The novel repeated impact tester provides valuable insights into the loading-history-dependent behavior of soft biomaterials, offering a new experimental capability for understanding damage mechanisms and advancing applications in biomedical engineering.