Inertial Microcavitation Rheometry of Anisotropic Biological Tissues
Abstract
Approved for public releaseDigital engineering harnesses predictive computational modeling for iterative engineering design that minimizes the need for expensive testing, and this approach has been deployed in the design of complex engineering systems. However, this process neglects loads and deformations applied to human occupants, which is a crucial aspect of predicting potential injuries and hence occupant safety. A key impediment to predictive digital engineering involving the mechanical interactions between humans and engineered systems is the high strain-rate constitutive behavior of biological tissues, which is required as an input but remains a source of uncertainty. Therefore, there is a need for improved constitutive modeling of biological tissues over a broad range of strain rates. Calibrated, predictive constitutive models for soft biological tissue materials are currently lacking because applying traditional high strain-rate material characterization techniques to soft materials is challenging. To address this need, a soft-material characterization technique, called Inertial Microcavitation Rheometry (IMR), has been developed using measurements of the dynamics of isolated bubbles generated by laser or acoustic pulses. Using high-speed imaging of the bubble dynamics along with a cavitation modeling framework provides a route to high strain-rate soft material characterization, and IMR has been shown to be able to discern mechanical properties at previously undocumented strain rates in materials as soft as a few kilopascals. In the proposed project, IMR will be leveraged to obtain calibrated high strain-rate constitutive models for several types of anisotropic biological tissue, including kidney, liver, and muscle tissue. To date, IMR has only been applied to obtaining material properties for isotropic models. The proposed work tackles the challenge of extending IMR to anisotropic materials. The first aim of the proposed project is to establish a robust methodology for applying IMR in an anisotropic material, using cleared muscle tissue as a benchmark optically-clear soft material, so that it may be verified that the anisotropic IMR process (a-IMR) yields consistent parameters for both isolatedbubbles and bubbles in thin slices. Then, the second aim moves to applying a-IMR to uncleared tissues of interest to the Naval Forces, specifically, kidney and liver. Finally, Aim 3 moves to applying a-IMR to skeletal muscle tissue, which is anticipated to be themost anisotropic biological material of interest. The proposed scope of work is Fundamental Research, having civil and military applications. Successful completion of the proposed work would result in a validated, extended version of IMR that is applicable to anisotropic materials and provide a set of robust, large-strain, high strain-rate material properties for biological tissues. This material property data will enable predictive digital engineering, potentially leading to improved strategies for mitigating and preventing injuries both in the armed forces and amongst civilians (e.g., in sports-related injuries).
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 12, 2025
- Source ID
- N000142512213
Entities
People
- Jonathan Estrada
Organizations
- Board of Regents of the University of Michigan
- Office of Naval Research
- United States Navy