Conductive Myocardial Patch with Negative Poisson's Ratio
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Solution Overview
Problem
Existing conductive myocardial patches face challenges in maintaining stable electrical conductivity during heart contractions due to mechanical mismatch with natural myocardium, leading to changes in electrical resistance and impaired signal transmission.
Innovation Solution
A conductive myocardial patch with a negative Poisson's ratio structure is developed, featuring a knitted or woven fabric with concave polygonal structural units and conductive coatings, which maintains stable conductivity and mechanical properties matching those of natural myocardium, ensuring strain insensitivity and effective electrical signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive layer is deposited on the surface of the myocardial patch substrate, then electrical conductivity is restored, but the conductive layer cracks when stretched due to mechanical mismatch, causing changes in electrical resistance
Solution Approach 1:
The patent uses a composite structure consisting of a polymer substrate combined with conductive polymer materials (such as polypyrrole, polyani line, or poly(3,4-ethylenedioxythiophene)). This composite approach allows the conductive layer to be integrated within the substrate matrix rather than being a separate deposited layer, enabling better mechanical coupling and preventing cracking during stretching while maintaining electrical conductivity.
2Stability of the object's composition
If conductive materials are dispersed inside the myocardial patch through spinning or gel process, then conductivity is maintained under large deformation, but the total path length of electrons increases and cross-sectional area decreases when stretched, leading to decreased conductivity
Solution Approach 1:
The patent incorporates conductive materials preferentially along the fiber direction or in specific orientations within the patch structure. This local concentration of conductive properties in the direction of electron transport minimizes the effect of path lengthening during stretching, as the conductive pathways are aligned with the primary direction of deformation, maintaining conductivity despite geometric changes.
3Object-affected harmful factors
If the myocardial patch uses materials such as collagen and alginate to ensure biocompatibility, then biocompatibility is achieved, but the mechanical properties are difficult to meet the requirements of traction force caused by heartbeat
Solution Approach 1:
The patent employs composite materials combining biocompatible polymers (such as collagen, alginate, or silk fibroin) with synthetic polymers having superior mechanical properties (such as polycaprolactone, polyglycolic acid, or poly(lactic-co-glycolic acid)). This composite strategy allows the patch to maintain excellent biocompatibility from the natural polymer components while gaining the necessary mechanical strength and elasticity from the synthetic polymer components to withstand heartbeat-induced traction forces.
4Adaptability or versatility
If the myocardial patch is designed to match the mechanical properties of healthy myocardium, then mechanical compatibility is achieved, but the electrical conductivity stability during heart contraction is compromised due to strain effects
Solution Approach 1:
The patent uses composite materials where the conductive polymer is integrated within a mechanically matched polymer matrix. The conductive polymer network is designed to be strain-insensitive through proper formulation and structure, allowing the composite to maintain both mechanical compatibility with beating heart tissue and stable electrical conductivity during the dynamic conditions of heart contraction and relaxation.
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 patch exhibits stable conductivity and mechanical properties that match the natural myocardium, effectively restoring electrical signal pathways and promoting myocardial regeneration and functional recovery without significant changes in conductivity during heartbeats.
Implementation Method 1
Materials with negative Poisson's ratio can expand in multiple directions at the same time, thereby affecting the synclastic curvature and shear strength
Implementation Method 2
The patch exhibits stable conductivity and mechanical properties that match the natural myocardium, effectively restoring electrical signal pathways
Data Source
AI summary
A stable conductive myocardial patch with a negative Poisson's ratio structure is provided. The preparation method includes preparing a myocardial patch substrate with concave polygons as the structural units by weaving or knitting, and then a conductive coating is coated on the surface of the substrate. Alternatively, the yarns can be processed into conductive coated yarns first, and then used as the raw material to weave or knit a stable conductive myocardial patch with a negative Poisson's ratio structure. The prepared myocardial patch has a relative resistance change of less than 5% at 50% tensile strain. When the strain of the structural units is within 50%, the fabric exhibits a negative Poisson's ratio structure, which expands in the perpendicular direction of the tensile load. The fabric exhibits a negative Poisson's ratio effect and anisotropy of Young's modulus, which matches the mechanical behavior of natural myocardium.