Conformable Implantable Stimulator Substrate with Ceramic Adhesion

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Solution Overview

Problem

Implantable electrical stimulation systems face challenges in aligning electrodes due to tissue curvature, leading to unpredictable electrical resistance and patient discomfort, with existing encapsulants like PDMS having high moisture permeability and limited biocompatibility, and traditional leads causing skin erosion and migration.

Innovation Solution

An implantable stimulator with a conformable substrate of thickness ≤0.5 mm, featuring a pulse generator, electrode array, and electrical interconnections, covered by a biocompatible encapsulation layer and adhesion layer, including ceramic materials like HfO2 and Al2O3, to enhance bonding and resistance to fluid ingress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If traditional cylindrical leads are used, then structural strength is maintained, but conformability to curved tissue surfaces deteriorates

Engineering Contradiction:

ImproveconformabilityVSAvoidstructural strength

Core Design Contradiction:

ShapeVSStrength

Solution Approach 1:

The patent employs a thin-film substrate (thickness ≤0.5 mm) as the structural base for the electrode array, replacing traditional cylindrical leads. This thin-film construction enables the device to conform to curved tissue surfaces while maintaining adequate structural strength through the use of flexible yet durable materials and design.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent utilizes composite material structures combining the thin-film substrate with encapsulation layers and adhesive layers. This multi-layer composite construction provides both conformability from the thin substrate and structural strength through the combined properties of different materials working together.

Inventive Principle:

Principle #40Composite materials

2Reliability

If PDMS encapsulant is used, then biocompatibility is improved, but moisture permeability increases

Engineering Contradiction:

Improveprotection from fluid ingressVSAvoidmoisture permeability

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent employs a multi-layer encapsulation system combining PDMS with other materials having complementary properties. This composite encapsulation structure leverages the biocompatibility of PDMS while compensating for its high moisture permeability through additional layers that provide barrier properties.

Inventive Principle:

Principle #40Composite materials

3Reliability

If adhesive layers are added to improve bonding, then encapsulant delamination is reduced, but device complexity increases

Engineering Contradiction:

Improvebonding strengthVSAvoidnumber of layers

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces an adhesive layer as an intermediary between the substrate and encapsulation layers. This intermediate layer specifically addresses the bonding interface problem, providing strong adhesion and preventing delamination without requiring fundamental changes to the existing structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Shape

If substrate thickness is reduced to ≤0.5 mm, then conformability is improved, but mechanical strength deteriorates

Engineering Contradiction:

ImproveconformabilityVSAvoidmechanical strength

Core Design Contradiction:

ShapeVSStrength

Solution Approach 1:

The patent successfully implements a thin-film substrate with thickness ≤0.5 mm that achieves both the required conformability and adequate mechanical strength. This is accomplished through careful material selection and design of the thin-film structure to provide sufficient strength while maintaining flexibility for conforming to tissue surfaces.

Inventive Principle:

Principle #30Flexible shells and thin films

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 provides improved comfort, reliability, and longevity of the implantable stimulator by increasing conformability, reducing electrical resistance, and protecting the electronics from bodily fluids, while maintaining biocompatibility.

Implementation Method 1

an encapsulation layer at least partially covering a portion of the substrate... acts as a barrier between these ionic fluids and critical electronic/electric interfaces

Methodology Applied

Scientific EffectPhysical barrier (encapsulation): Physical Containment

Implementation Method 2

an adhesion layer between the encapsulation layer and the substrate... bonding these two flexible materials remains a crucial challenge

Methodology Applied

Scientific EffectChemical bonding (adhesion): Adhesive

Data Source

PatentUS20210387001A1Implantable stimulator with an electrode array, conformable substrate, and mechanical strain relief

Publication Date: 2021.12.16 SALVIA BIOELECTRONICS BV

AI summary

An implantable stimulator is provided having a substrate comprising a conformable portion with an electrode array, and a pulse generator. A plurality of electrical interconnections 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 may be provided. Optionally, one or adhesion layers 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.