Membrane research: the component that carries every heartbeat
Multilayer membranes made of elastomeric and polymeric materials are under investigation, including PU/PCU- and silicone-based systems. The focus is fatigue, wrinkling, edge stress and reproducible motion over very high cycle counts.
Why the membrane
Separating wall and wear part at once
The membrane separates the blood space from the mechanical space. It is deformed by the pressure plate with every stroke — at a mean flow of 7.5 l/min and a 120 ml stroke volume about 62.5 times per minute, or roughly 328.5 million times over ten years.
Fatigue typically does not start in the open surface but at clamped edges, in regions of high curvature and in repeated contact zones. The membrane is therefore investigated together with its clamping, the pressure-plate geometry and the motion profile rather than as an isolated material.
Systematic material and membrane development began in March 2024.
Materials
Membrane and elastomer materials under investigation
| Material | Classification | Status |
|---|---|---|
| PU / PCU | polyurethane / polycarbonate urethane | Under investigation |
| BPU | polyurethane variant | Under investigation |
| Silicone | elastomer; earlier working assumption: silicone membrane approx. 2 mm | Under investigation |
| EPDM | elastomer | Under investigation |
| Multilayer build / rolling diaphragm | research focus | Under investigation |
The 2 mm silicone membrane is an earlier working assumption, not a final specification. A material is only selected once endurance data exists.
Research questions
What has to be tested on the membrane
- Fatigue over very high cycle counts
Cycle life under realistic pressure loads — short demonstrations are not durability evidence.
- Wrinkling and reproducible motion
The membrane should roll the same way with every stroke and not form migrating wrinkles.
- Edge stress and clamping
Clamped edges and transitions to the pressure plate are the most likely starting points for cracks.
- Tightness and leakage
Leakage checks and membrane inspection belong to every endurance interval.
- Blood contactOpen
The membrane surface contacts blood — hemocompatibility is a separate, still open proof. See validation.
Approach
From specimen to endurance run
- Requirements and membrane designIn progress
03/2024 – 12/2026
- Material selection, casting and specimensIn progress
03/2024 – 12/2027
- Oil-bath and preload experimentsPlanned
Benchtop test approaches for cyclic loading.
- Durability test rigIn progress
06/2025 – 12/2026: cyclic loading and membrane studies.
- Endurance, failure analysis, iterationIn progress
01/2026 – 12/2028