Interchangeable Ventricle Phantom: Material & Fabrication Overview

Why Ecoflex 00-30?

Fabrication Workflow

• Medical imaging (CT or MRI) is segmented to reconstruct ventricular geometry
• The mold is 3D-printed (typically FDM or SLA) in a rigid polymer (PLA, ABS, or resin)
• The mold defines both inner and outer wall contours of the phantom ventricle

• Ecoflex 00-30 parts A and B are mixed 1:1 by weight or volume
• The mixture is vacuum degassed to remove entrapped air bubbles
• It is poured into the mold and allowed to cure at room temperature (typically 4 hours)
• Post-cure, the mold is removed - leaving the patient-specific silicone ventricle shell

• The ventricle chamber can be swapped in and out of a flow loop or benchtop test rig
• This allows testing of different pathological geometries (dilated, hypertrophic, post-infarct) without rebuilding the entire system
• Multiple phantoms can represent different patients or disease states

Why This Enables Realistic Valve Deployment and Stent-Wall Interaction

• The low stiffness of Ecoflex 00-30 lets the silicone wall deform under the radial expansion force of a deployed stent-valve, mimicking how the native annulus and LVOT resist and recoil against the device
• Overly stiff phantom walls would prevent physiological crimping, flaring, and anchoring behavior

• When a stent expands, it imposes a radial force on the surrounding tissue - the phantom wall deflects in proportion to its stiffness
• Ecoflex's Young's modulus in the ~20-25 kPa range sits within (or just below) the passive myocardial stiffness range (~10-200 kPa depending on phase of cardiac cycle), enabling contact stress distributions and device apposition patterns that are representative of in vivo conditions
• Mismatch in stiffness (too stiff) would overestimate device anchoring force and underestimate wall motion artifacts

Key Limitations to Note

• Ecoflex 00-30 is isotropic and linearly elastic at physiological strain rates, whereas native myocardium is anisotropic and viscoelastic with fiber-direction-dependent stiffness and a nonlinear toe region
• The modulus of Ecoflex (~20-25 kPa) is actually softer than the measured left ventricle short-axis modulus (0.1-0.16 N/mm² = 100-160 kPa in the paper above), so it best approximates the low-strain, passive diastolic stiffness regime rather than systolic active stiffness
• Mixtures of Dragon Skin 10Slow + Ecoflex 00-30 can be tuned to better match specific tissues if needed

Supporting Literature

• Mechanical testing of porcine tissue vs. silicones (PMC) - directly benchmarks Ecoflex 00-30 against cardiovascular tissue moduli
• Smooth-On's Ecoflex 00-30 product data - Shore 00-30, 1:1 mix ratio, room-temperature cure
• Janardhana et al. (2025, MDPI Materials) reported initial Young's modulus of ~25 kPa for Ecoflex 00-30