Volume-controlled Cavity Expansion for Probing of Local Elastic Properties in Soft Materials

Ability to measure the mechanical properties of soft biological materials in vivo can enable physicians in offering more accurate diagnosis of diseases such as cancer. Needle-based cavity expansion techniques are thus capturing the attention of researchers for measurement of the local nonlinear elastic properties in soft materials. Here we introduce a volume-controlled cavity expansion procedure that builds on the Cavitation Rheology technique [1] without relying on the maximum recorded pressure. We show that by employing an effective cavity radius based on our volume measurements we can consistently collapse the experimental results onto the theoretical predictions, regardless of the specific damage or instability mechanism exhibited by the material. We confirm the applicability of this technique by using PDMS samples, presenting good agreement with results obtained via conventional techniques with less than 5% of scatter. Moreover, since this method does not require visual tracking of the cavity, it can be applied to measure the nonlinear elastic response in opaque samples.

[1] Zimberlin, et al. Soft Matter, 2007.