Hyperelastic modelling and parametric study of soft tissue embedded lump for MIS applications

Area of Science:

• Biomedical Engineering
• Surgical Technology
• Materials Science

Background:

• Minimally invasive surgery (MIS) instruments limit surgeons' tactile feedback, hindering palpation for tissue assessment and lump detection.
• Current smart endoscopic graspers aim to restore tactile sensation, but the impact of anatomical features like lumps on stress distribution remains understudied.

Purpose of the Study:

• To investigate how lump parameters (size, depth, stiffness) influence stress distribution on smart MIS graspers.
• To validate a hyperelastic finite element analysis model for simulating lump-tissue interactions.

Main Methods:

• Obtained material parameters from experimental stress-strain compression tests for the Mooney-Rivlin model.
• Performed hyperelastic finite element analysis to simulate stress distribution under varying lump conditions.
• Validated simulation results against experiments using elastomeric materials mimicking soft tissue.

Main Results:

• Demonstrated the influence of lump size, depth, and stiffness on contact surface stress distribution.
• Validated non-linear finite element analysis (FEA) results against experimental data.

Conclusions:

• The FEA model, based on hyperelastic formulation, is validated by experimental consistency.
• FEA results are crucial for developing an inverse model to determine lump characteristics (size, depth, stiffness) from sensor outputs.