Additive Manufacturing to Mimic the Nonlinear Mechanical Behavior of Cardiac Soft Tissue.

Area of Science:

• Biomedical Engineering
• Materials Science
• Mechanical Engineering

Background:

• Soft biological tissues exhibit complex nonlinear and anisotropic mechanical properties essential for physiological function.
• Replicating these properties in engineered materials via additive manufacturing is crucial for biomedical applications like surgical simulation and device development.
• The left atrial appendage (LAA) is a key anatomical structure involved in thrombus formation during atrial fibrillation, making it a relevant model for studying cardiovascular conditions.

Purpose of the Study:

• To establish a framework for reproducing the nonlinear stress-strain behavior of soft biological tissues using 3D-printed models.
• To investigate the potential of additive manufacturing in creating anatomically accurate and functionally representative soft tissue models.
• To optimize printing parameters for achieving reliable structural and mechanical performance in 3D-printed soft tissue analogs.

Main Methods:

• Selection of two polymers, polyurethane (TPU) and a thermoplastic elastomer (TPE), chosen for their tunable hardness and elasticity.
• A parametric study was conducted to evaluate the influence of Shore A hardness, infill density, and external shell number on the tensile performance of 3D-printed models.
• Mechanical testing was performed on the printed models to obtain stress-strain curves and assess their mechanical response.

Main Results:

• The study successfully demonstrated the ability to replicate nonlinear stress-strain behavior characteristic of soft tissues using 3D printing.
• Parametric variations in material properties (Shore A hardness) and printing parameters (infill density, shell number) significantly affected the tensile performance of the models.
• The selected polymers, TPU and TPE, proved suitable for creating soft tissue models with tunable mechanical characteristics.

Conclusions:

• Additive manufacturing offers a viable approach for the anatomical reproduction of soft tissues.
• The developed framework enables the creation of 3D-printed models that replicate the functional mechanical properties of native soft tissues.
• These advanced soft tissue models have significant potential for applications in surgical simulation, medical device development, and preclinical testing.