Cochlear Implant Electrode with Mechanical Hydrogel Fixation

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Solution Overview

Problem

The existing hydrogel materials used to cover electrode contacts in cochlear implants swell when exposed to perilymph fluid, causing them to separate from the electrode array due to insufficient mechanical fixation, which hampers effective charge transfer and tissue integration.

Innovation Solution

A cochlear implant electrode array with a resilient material and a mechanically fixed biocompatible hydrogel layer, utilizing fixation grooves and hydrogel sleeves with a polymer mesh to resist separation and generate compressive forces, ensuring the hydrogel layer remains attached and functional.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If hydrogel material is used to cover electrode contacts, then biocompatibility and charge transfer are improved, but the hydrogel separates from the electrode array due to swelling

Engineering Contradiction:

Improvecharge transferVSAvoidhydrogel attachment

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The electrode array is divided into multiple segments with individual fixation grooves at different positions. Each groove independently secures a portion of the hydrogel layer, creating multiple attachment points that collectively prevent separation while allowing controlled swelling.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The hydrogel layer is nested within the fixation grooves of the electrode array structure. The grooves are formed within the electrode array body, creating a nested configuration where the hydrogel is mechanically contained without requiring external fastening mechanisms.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Adaptability or versatility

If hydrogel material swells upon contact with perilymph fluid, then tissue integration is improved, but the hydrogel forces itself away from the electrode surface

Engineering Contradiction:

Improvetissue integrationVSAvoidswelling force

Core Design Contradiction:

Adaptability or versatilityVSForce

Solution Approach 1:

Fixation grooves are pre-formed in the electrode array before hydrogel application. These grooves create preliminary mechanical constraints that counteract the swelling forces before they can cause separation. The grooves are strategically positioned to provide resistance against the direction of swelling-induced displacement.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The hydrogel layer acts as a flexible film that can swell within the confines of the fixation grooves. The grooves provide a flexible containment structure that accommodates volume changes while maintaining attachment, allowing the hydrogel to expand without detaching from the electrode surface.

Inventive Principle:

Principle #30Flexible shells and thin films

3Strength

If chemical bonds are used to connect hydrogel to electrode array, then attachment strength is improved, but the bonds fail under swelling induced forces

Engineering Contradiction:

Improveattachment strengthVSAvoidattachment durability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

Chemical bonding mechanisms are replaced with mechanical fixation using physical grooves. The fixation grooves provide mechanical interlocking through friction and geometric constraints, eliminating reliance on chemical bonds that fail under swelling forces. This mechanical substitution provides durable attachment that withstands the dynamic swelling environment.

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 mechanical fixation of the hydrogel layer prevents separation from the electrode array, maintaining effective electrical stimulation and tissue integration, while allowing for potential drug release over a prolonged period.

Implementation Method 1

The hydrogel materials swells when it contacts the perilymph fluid within the cochlea, absorbing more than its own dry weight.

Methodology Applied

Scientific EffectHydrogel swelling: Absorption (physical)

Implementation Method 2

a polymer mesh over each hydrogel sleeve that is adapted to generate a compressive force on the hydrogel sleeve when it swells

Methodology Applied

Scientific EffectCompressive force generation: Mechanical Force

Data Source

PatentEP3041444B1Electrode contact with hydrogel covering

Publication Date: 2023.07.19 MED EL ELEKTROMEDIZINISCHE GERAETE GMBH

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Figure 3A~3C

AI summary

A cochlear implant electrode includes an implantable electrode array made of resilient material with a center longitudinal axis and an outer surface. Electrode contacts are distributed on the outer surface of the electrode array along the longitudinal axis for applying electrical stimulation signals to adjacent neural tissue. At least one biocompatible hydrogel layer is fixed to the electrode array solely by mechanical connection and adapted to swell from contact with perilymph fluid within a cochlea without separating away from the outer surface of the electrode array.