Self-Cleaning Porous Layer for Blood Contacting Devices
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Solution Overview
Problem
Current blood-contacting medical devices, such as vascular grafts and stents, are prone to thrombus formation due to interactions with foreign materials and hemodynamic disruptions, leading to device failure and patient safety risks, with existing solutions like heparin and PEG coatings having limitations such as degradation and adverse effects.
Innovation Solution
A self-cleaning porous layer or coating composed of synthetic biodegradable and nonbiodegradable materials, including electrospun fibers, is applied to blood-contacting surfaces to control reversal fluid flow, minimizing platelet activation and thrombosis by allowing blood to flow into and away from the surface during cardiac cycles, thus reducing platelet adsorption and thrombogenesis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heparin coating is applied to blood contacting devices, then thrombosis formation is reduced through interference with coagulation signaling pathways, but the coating degrades upon exposure to biological environment and can detrimentally affect the coagulation cascade leading to hemorrhage
Solution Approach 1:
The patent applies a porous layer composed of nanofibers to the blood contacting surface. This porous structure allows plasma to penetrate through and form a transient protein film that is rapidly removed by reversal flow, providing thrombosis resistance without relying on degradable chemical coatings like heparin.
Solution Approach 2:
The device utilizes the body's own physiological processes (pulsatile blood flow creating reversal flow during diastole) to automatically clean the surface by removing adsorbed platelets and proteins. The system serves itself without requiring external intervention or degradable chemical agents.
2Reliability
If PEG coating is applied to increase hydrophilicity and diminish protein adsorption, then thrombogenicity is reduced, but the function is compromised during exposure to biological environment leading to inconsistent in-vivo results
Solution Approach 1:
The patent changes the approach from modifying surface chemistry (PEG coating) to modifying surface topology (porous nanofiber structure). The physical structure enables plasma penetration and transient protein film formation that is then removed by reversal flow, providing consistent thrombogenicity resistance without biological environment compromise.
3Reliability
If surface topographical modification is used to reduce platelet-material interaction, then thrombosis is inhibited, but chemical-based surface functionalization is limited and requires degradation of chemical reactions
Solution Approach 1:
The patent extracts the thrombosis prevention function from complex chemical surface functionalizations and implements it through a purely physical porous nanofiber structure. The nanofibers create a topographical surface that promotes plasma penetration and transient protein film formation without requiring any chemical reactions or functionalizations.
4Strength
If compliance-mismatch between native artery and vascular graft is present, then asynchronous expansion and recoil occur altering blood flow patterns, but this causes non-physiologic mechanical strain on endothelial cells and activates platelets leading to thrombosis
Solution Approach 1:
The porous nanofiber layer allows plasma to penetrate through during systole and be removed during diastole via reversal flow. This physical cleaning action counteracts the harmful effects of non-physiologic blood flow patterns and mechanical strain caused by compliance-mismatch, preventing platelet activation despite the mechanical issues.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The porous layer effectively reduces platelet activation and thrombus formation by destabilizing protein films and using fluid momentum to repel platelets, minimizing device failure and patient risk while maintaining mechanical properties and avoiding chemical interference with coagulation cascades.
Implementation Method 1
control reversal fluid flow there through... allowing blood to flow into and away from the surface during cardiac cycles
Implementation Method 2
using fluid momentum to repel platelets
Implementation Method 3
minimizing platelet activation and thrombosis by allowing blood to flow into and away from the surface... destabilizing protein films
Data Source
AI summary
The invention relates to self-cleaning porous structures, e.g., layers or coatings, fabricated within, applied to, or deposited on a blood contacting surface of a medical device, to prevent activation and aggregation of platelets thereon. In certain embodiments, the layer or coating is composed of multi-layered fibers. The porous structure is applied to or deposited such as to form a permeable wall on the blood contacting surface. The blood travels into the wall and subsequently back out (reversing back into the lumen) during a cardiac cycle. Reversal flow is controlled during the diastole phase such that the backward flow repels the platelets and prevents their activation and aggregation and therefore, minimizes thrombus formation.