Mimicking the Mechanical Properties of Aortic Tissue with Pattern-Embedded 3D Printing for a Realistic Phantom

Abstract

3D printing technology has been extensively applied in the medical field, but the ability to replicate tissues that experience significant loads and undergo substantial deformation, such as the aorta, remains elusive. Therefore, this study proposed a method to imitate the mechanical characteristics of the aortic wall by 3D printing embedded patterns and combining two materials with different physical properties. First, we determined the mechanical properties of the selected base materials (Agilus and Dragonskin 30) and pattern materials (VeroCyan and TPU 95A) and performed tensile testing. Three patterns were designed and embedded in printed Agilus-VeroCyan and Dragonskin 30-TPU 95A specimens. Tensile tests were then performed on the printed specimens, and the stress-strain curves were evaluated. The samples with one of the two tested orthotropic patterns exceeded the tensile strength and strain properties of a human aorta. Specifically, a tensile strength of 2.15 ± 0.15 MPa and strain at breaking of 3.18 ± 0.05 mm/mm were measured in the study; the human aorta is considered to have tensile strength and strain at breaking of 2.0-3.0 MPa and 2.0-2.3 mm/mm, respectively. These findings indicate the potential for developing more representative aortic phantoms based on the approach in this study.

Keywords: 3D printing; aorta; multi-materials; pattern embedding; tensile testing.

Figure 1

Multi-layered structure of a typical aortic wall.

Figure 2

Typical stress-strain curve for soft tissue in the uniaxial tensile test: (a) elastin phase; (b) transition phase; (c) collagen phase; and (d) rupture [29]. (${\sigma }_y\ge 2.0$ MPa, ${\epsilon }_r\ge 2.0$ mm/mm).

Figure 3

Specimen dimensions for (a) ASTM D638 and (b) ASTM D412 [36,37].

Figure 4

Pattern-embedded specimens: (a) Pattern A aligned with the major axis; (b) Pattern A aligned with the minor axis; (c) Pattern B aligned with the major axis; (d) Pattern B aligned with the minor axis; and (e) Pattern C.

Figure 5

3D printed specimen mold and pattern-embedded specimens: (a) 3D printed specimen mold for Pattern A with major axis alignment; (b) 3D printed pattern-embedded specimens; and (c) silicon-molded pattern-embedded specimens.

Figure 6

3D printed pattern-specimens of TPU 95A.

Figure 7

Stress-strain curves of the base materials. Mean stress-strain curves before yield for the: (a) Agilus; (b) VeroCyan; (c) Dragonskin 30; and (d) TPU 95A.

Figure 8

Stress-strain curve and modulus of elasticity of the Pattern C Dragonskin 30–TPU 95A specimens with a 1.4 mm pattern diameter: (a) stress-strain curve before yield and (b) modulus of elasticity.