Plasma-Modified SMP Foam for Aneurysm Embolization

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Solution Overview

Problem

Current treatments for intracranial aneurysms using bare platinum coils are limited by high costs, incomplete embolization, and risk of aneurysm rupture due to over-packing, with low-density shape memory polymer (SMP) foams offering promise but requiring improved delivery and actuation methods for clinical effectiveness.

Innovation Solution

A plasma-enhanced chemical vapor deposition (PECVD) process is used to create a hydrocarbon surface diffusion barrier on SMP foams, delaying moisture plasticization and enabling nonlinear expansion, while reticulation increases permeability and thrombogenicity, allowing for controlled actuation and expanded surface area within the aneurysm.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If low density SMP foams are compressed to fractions of their expanded volume for delivery, then they can be delivered through microcatheters, but they require controlled expansion after implantation to achieve therapeutic effect

Engineering Contradiction:

Improvefoam delivery volumeVSAvoidcontrolled expansion

Core Design Contradiction:

Volume of moving objectVSEase of operation

Solution Approach 1:

The patent applies parameter changes by controlling the glass transition temperature (Tg) of the SMP foam through plasticizer content and surface modification. By adjusting the Tg parameter, the foam remains in a rigid compressed state during delivery, then transitions to a compliant expanded state after implantation when exposed to body temperature and moisture, enabling controlled expansion without mechanical actuation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent utilizes phase transitions of the shape memory polymer material. The foam transitions from a glassy rigid phase during compressed delivery to a rubbery compliant phase after implantation when exposed to body temperature and moisture. This phase transition enables the foam to automatically expand to its programmed geometry without requiring external actuation mechanisms

Inventive Principle:

Principle #36Phase transitions

2Reliability

If more bare platinum coils are used to increase packing density, then embolization effectiveness improves, but the risk of aneurysm rupture due to over-packing increases

Engineering Contradiction:

Improveembolization effectivenessVSAvoidaneurysm rupture risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces expensive bare platinum coils with a single low-density SMP foam embolic device that can be delivered through a microcatheter. The foam provides volumetric filling of the aneurysm without requiring multiple overlapping coils, thereby eliminating the risk of over-packing and aneurysm rupture while maintaining embolization effectiveness

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent uses a flexible SMP foam structure that can conform to the irregular geometry of the aneurysm sac. The foam's flexibility allows it to adapt to the aneurysm shape and provide uniform volumetric filling without creating localized stress concentrations that could lead to rupture, unlike rigid overlapping coils

Inventive Principle:

Principle #30Flexible shells and thin films

3Duration of action of moving object

If plasma surface modification is applied to SMP foams, then working time for delivery is extended and expansion is controlled, but the manufacturing process complexity increases

Engineering Contradiction:

Improveworking timeVSAvoidmanufacturing process

Core Design Contradiction:

Duration of action of moving objectVSDevice complexity

Solution Approach 1:

The patent replaces mechanical expansion control mechanisms with a chemical surface modification approach. Plasma treatment creates a hydrophobic surface layer that delays moisture penetration and plasticization, thereby controlling the expansion timing. This chemical approach is simpler than mechanical actuation systems while effectively extending working time for safe delivery through microcatheters

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 method extends the working time for SMP foam delivery through microcatheters, reduces the number of coils needed, and enhances volumetric occlusion and surface area, improving embolization efficacy and safety by controlling expansion and permeability.

Implementation Method 1

A plasma-enhanced chemical vapor deposition (PECVD) process is used to create a hydrocarbon surface diffusion barrier on SMP foams

Methodology Applied

Scientific EffectPlasma-enhanced chemical vapor deposition: Plasma Enhanced Chemical Vapour Deposition

Implementation Method 2

modifying the surface of the polymer using plasma

Methodology Applied

Scientific EffectPlasma oxidation: Oxidation

Data Source

PatentUS11459439B2Surface modification of polymer foams using plasma

Publication Date: 2022.10.04 LAWRENCE LIVERMORE NAT SECURITY LLC

AI summary

An embodiment includes a system comprising: a monolithic shape memory polymer (SMP) foam having first and second states; wherein the SMP foam includes: (a) polyurethane, (b) an inner half portion having inner reticulated cells defined by inner struts, (c) an outer half portion, having outer reticulated cells defined by outer struts, surrounding the inner portion in a plane that provides a cross-section of the SMP foam, (d) hydroxyl groups chemically bound to outer surfaces of both the inner and outer struts. Other embodiments are discussed herein.