Abstract:
"Measurements of Soft-Tissue Mechanical Properties to Support Development of a Physically Based Virtual Animal Model"
This paper outlines the methods used to acquire the mechanical properties of rat soft tissues to support the development of a physically-based "Virtual Rat" surgical training simulator. The authors identify the limitations of traditional mass-spring models, which often rely on arbitrary spring constants for visual appeal, and advocate for more realistic simulations using Finite Element (FE) or hybrid models that are driven by the constitutive properties of the tissues themselves. To achieve this, a protocol was developed for measuring the force-displacement response of various rat organs, including the liver and kidney, under both in situ and in vitro conditions. A specialized instrument, the TeMPEST 1-D, was used to apply controlled, high-frequency deformations with a 5mm circular punch, capturing data relevant for haptic feedback simulations. The experimental results, presented as compliance transfer functions, indicated that while the tissues exhibit some viscous behavior, they can be approximated as elastic for initial modeling, which simplifies computation. To interpret the experimental data and extract material parameters like Young's Modulus, the researchers created an FE model of a rat kidney from high-resolution CT scans and simulated the testing scenario. The study demonstrates the significant difference in tissue deformation in a mass-spring system when using uniform spring constants versus constants derived from these measured biomechanical properties, underscoring the importance of this work for creating a more realistic and meaningful virtual training experience.
