Conformable Implantable Stimulator Substrate for Skin Erosion
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Solution Overview
Problem
Implantable electrical stimulation systems face challenges in precisely aligning electrodes due to tissue curvature, leading to unpredictable electrical resistance and patient discomfort, with existing solutions like deformable leads being inconvenient and prone to skin erosion or migration.
Innovation Solution
A conformable implantable stimulator with a foil-like substrate and electrode array, embedded in flexible biocompatible encapsulation layers like PDMS, featuring a ceramic adhesion layer for improved bonding and resistance to fluid ingress, allowing for precise energy transfer and increased comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a cylindrical lead is used for implantation, then the lead can be easily manufactured and implanted, but the lead creates skin erosion and migration due to its thickness and rigidity
Solution Approach 1:
The patent replaces the traditional cylindrical lead structure with a thin, flexible, planar electrode array that can conform to curved tissue surfaces. This thin-film construction eliminates skin erosion caused by thick cylindrical leads and prevents migration by allowing the electrodes to adapt to tissue curvature, thereby resolving the contradiction between ease of manufacture and harmful effects on skin.
Solution Approach 2:
The patent designs the electrode array with a curved configuration that matches the natural curvature of anatomical structures. This curved design allows the thin flexible electrodes to conform to tissue surfaces, preventing skin erosion and migration while maintaining ease of manufacture through standardized curved geometries.
2Shape
If the electrode array is made thin and flexible to conform to tissue, then conformability improves, but protection against bodily fluids becomes compromised
Solution Approach 1:
The patent employs a composite structure consisting of a thin flexible substrate made from fluid-resistant materials such as polyimide or parylene, combined with conductive electrode layers and protective coatings. This composite construction maintains conformability through flexibility while providing reliable protection against bodily fluids through the inherent fluid resistance of the polymeric materials and encapsulation layers.
3Reliability
If traditional encapsulation methods are used with flexible substrates, then electronics are protected from bodily fluids, but bonding reliability decreases due to delamination
Solution Approach 1:
The patent modifies the chemical and physical parameters of the encapsulation interface by using plasma treatment, chemical etching, or adhesion promoters on the flexible substrate surface. These parameter changes enhance the bonding strength between the encapsulation layer and the flexible substrate, preventing delamination while maintaining fluid protection and conformability.
Solution Approach 2:
The patent introduces an intermediary adhesion layer or coupling agent between the flexible substrate and the encapsulation material. This intermediary layer improves interfacial bonding and prevents delamination, thereby maintaining both fluid protection and structural stability without compromising conformability.
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 solution enhances conformability and reliability, reducing electrical resistance and patient discomfort by providing a high degree of flexibility and protection against bodily fluids, thus improving the longevity and effectiveness of the implantable stimulator.
Implementation Method 1
Encapsulation is thus a critical component for the design of a medical device - it acts as a barrier between these ionic fluids and critical electronic/electric interfaces to reduce and/or prevent degradation of the implant electronics
Implementation Method 2
The adhesive layer comprises a ceramic material and is configured and arranged to bond to the substrate and the encapsulation layer
Data Source
Figure 1A~1C
Figure 2A~2C
Figure 3A~3C
AI summary
The use of neurostimulation leads in the craniofacial region is associated with skin erosion and lead migration. The cylindrical shape and associated thickness of state-of-the-art leads results in the lead eroding through the skin or results in the lead being displaced so that the electrodes no longer cover the targeted nerves. An implantable stimulator 1001110 is provided having a substrate 300, 1400 comprising a conformable portion with an electrode array, and a pulse generator 500. A plurality of electrical interconnections 250, 1210 are positioned between the surfaces of the substrate The conformable portion has a thickness equal to or less than 0.5 millimeters. Optionally, one or more encapsulation layers 1300 may be provided. Optionally, one or adhesion layers 1500 may also be provided comprising a ceramic material. By providing a more easily patternable substrate, more complicated electrode array configurations may be supported, allowing a higher degree of flexibility to address transverse and/or longitudinal misalignment. By providing a relatively thin implantable electrode array, user comfort may be increased. The one or more adhesion layers improve the performance of the encapsulation.