Illi Joël, Bergamin Manuel, Ilic Marc, Stark Anselm W, Bracher Stefan, Hofmann Martin, Burger Juergen, Shiri Isaac, Haeberlin Andreas, Gräni Christoph
Department of Cardiology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland.
Front Bioeng Biotechnol. 2025 May 30;13:1569553. doi: 10.3389/fbioe.2025.1569553. eCollection 2025.
Cardiovascular patient-specific phantoms can improve patient care through testing and simulation. However, materials like silicone and 3D-printing polymers differ mechanically from biological tissues. Agilus30 Clear, the primary material for 3D-printed phantoms, is much stiffer, nearly isotropic, and lacks strain-hardening behavior. To overcome these challenges, a novel 3D voxel-printing approach may provide an effective solution.
METHODS/AIM: This study aimed to explore the applicability of 3D voxel printing, assess how different parameters (strand structure, density, and orientation) affect mechanical properties, and compare them to established phantom materials and porcine cardiovascular tissues. Progressive uniaxial cyclic tension tests were performed across nine stages, varying strain rates and target strain levels, with elastic modulus calculated for comparison. The goal was to stepwise assess whether the overall material stiffness can be reduced, achieving anisotropy and replicating strain-hardening behavior.
In the first step, varying the strand density, the tested samples showed a 0%-60% strain modulus of elasticity of 0.215-0.278 N/mm, representing a 4-5-fold reduction in elastic modulus compared to that of the base material, Agilus30 Clear. In the second step, varying the orientation of the structures had a significant influence on the elastic modulus, which was measured. The 0%-60% modulus of elasticity decreased to 0.161-0.192 N/mm, displaying anisotropic material behavior. In the third step, two strand structures specifically designed to mimic fiber recruitment were tested. These resulted in slightly flatter (more linear) stress-strain curves compared to the non-linear strain-softening behavior observed in Agilus30 Clear. However, they still fell short of replicating the desired non-linear strain-hardening behavior characteristic of fiber recruitment in cardiovascular tissues.
The novel 3D voxel-printing material approach resulted in reduced elastic modulus, anisotropic behavior, and strain-hardening properties, providing a much closer representation of the mechanical behavior of porcine cardiovascular tissues compared to other available phantom materials. However, there is still significant potential for optimization through further exploration of fiber recruitment replication.
心血管疾病患者特异性模型可通过测试和模拟改善患者护理。然而，硅胶和3D打印聚合物等材料在力学性能上与生物组织不同。3D打印模型的主要材料Agilus30 Clear硬度更高、近乎各向同性且缺乏应变硬化行为。为克服这些挑战，一种新型的3D体素打印方法可能提供有效的解决方案。
方法/目的：本研究旨在探索3D体素打印的适用性，评估不同参数（股线结构、密度和方向）如何影响力学性能，并将其与已有的模型材料和猪心血管组织进行比较。在九个阶段进行了渐进单轴循环拉伸试验，改变应变率和目标应变水平，并计算弹性模量进行比较。目标是逐步评估整体材料刚度是否可以降低，实现各向异性并复制应变硬化行为。
第一步，改变股线密度，测试样品的0%-60%应变弹性模量为0.215-0.278N/mm，与基础材料Agilus30 Clear相比，弹性模量降低了4-5倍。第二步，改变结构方向对测量的弹性模量有显著影响。0%-60%弹性模量降至0.161-0.192N/mm，显示出各向异性材料行为。第三步，测试了两种专门设计用于模拟纤维募集的股线结构。与Agilus30 Clear中观察到的非线性应变软化行为相比，这些结构导致应力-应变曲线略为平缓（更线性）。然而，它们仍未复制心血管组织中纤维募集所需的非线性应变硬化行为特征。
新型3D体素打印材料方法降低了弹性模量、呈现各向异性行为和应变硬化特性，与其他可用的模型材料相比，更接近猪心血管组织的力学行为。然而，通过进一步探索纤维募集复制，仍有很大的优化潜力。
