Elastic Ear Canal Impression Pad with Scalloped Inner Surface

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Solution Overview

Problem

Current impression-taking methods for ear canals often result in incomplete or inaccurate impressions, particularly beyond the second bend, leading to insufficient information for custom hearing device production, discomfort for users, and increased costs due to repeated procedures and the inability to accurately capture ear canal geometry and sound output direction.

Innovation Solution

An elastic impression-taking pad with a hollowed dome-shaped contour and axially aligned scallops on its inner surface, providing even pressure distribution and improved bonding with impression material, allowing for complete and accurate reproduction of the ear canal geometry without the need for removal before scanning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If standard foam pads are used for impression-taking, then the eardrum is protected from liquid impression material, but the foam does not connect well to the impression material resulting in holes and loss of ear canal feature information

Engineering Contradiction:
Improvesealing protectionVSAvoidear canal feature information
Core Design Contradiction:
ReliabilityVSLoss of information

Solution Approach 1:

The impression-taking pad uses a porous elastomeric material structure that allows liquid impression material to penetrate and bond effectively, eliminating holes while maintaining sealing protection. The porous structure enables mechanical interlocking between the pad and impression material.

Inventive Principle:
Principle #31Porous materials

Solution Approach 2:

The invention uses a composite structure combining an elastomeric base material with integrated porous layers or surface treatments, creating a multi-functional material that provides both sealing protection and strong bonding to impression material without information loss.

Inventive Principle:
Principle #40Composite materials

2Reliability

If foam pads are used to prevent liquid impression material from reaching the eardrum, then protection is provided, but the foam pads expand after impression-taking causing loss of accurate geometric information

Engineering Contradiction:
Improveeardrum protectionVSAvoidgeometric information accuracy
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The invention changes the material parameters by using cross-linked elastomeric materials with controlled durometer values and minimal expansion properties, preventing the foam expansion issue while maintaining eardrum protection through proper material selection and formulation.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If standard foam pads are used, then eardrum protection is achieved, but the pads often crackle in the ear canal causing discomfort and potentially reducing impression length

Engineering Contradiction:
Improveeardrum protectionVSAvoiduser discomfort
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention changes material parameters by selecting elastomeric materials with optimized durometer values, hysteresis characteristics, and damping properties that eliminate crackling sounds while maintaining protective function and user comfort during impression-taking.

Inventive Principle:
Principle #35Parameter changes

4Ease of operation

If foam pads are cut back to fit the ear canal, then proper fit is achieved, but the cutting process is time-consuming and costly

Engineering Contradiction:
Improveear canal fitVSAvoidimpression-taking efficiency
Core Design Contradiction:
Ease of operationVSProductivity

Solution Approach 1:

The invention applies preliminary action by pre-forming the impression-taking pad with an optimized contour that matches the ear canal geometry, eliminating the need for post-manufacturing cutting operations and improving workflow efficiency.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention uses elastomeric materials with optimized physical properties including durometer values and memory characteristics that enable the pad to self-adjust and conform to the ear canal without requiring mechanical cutting, thereby improving productivity.

Inventive Principle:
Principle #35Parameter changes

5Manufacturing precision

If the impression needs to extend beyond the second bend to capture complete ear canal geometry, then accurate hearing device positioning is achieved, but the thin skin layer in this region is very sensitive to applied pressure

Engineering Contradiction:
Improveear canal geometry reproductionVSAvoidpressure sensitivity
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The invention changes the pressure distribution characteristics by using materials with optimized durometer values and elastic properties, allowing the pad to extend beyond the second bend with distributed, gentle pressure that does not harm the thin skin layer while capturing complete geometric information.

Inventive Principle:
Principle #35Parameter changes

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 pad ensures a high-quality, complete, and continuous impression surface, enabling precise reproduction of the ear canal anatomy, including beyond the second bend, reducing the need for repeated procedures and improving the fit and alignment of hearing devices.

Implementation Method 1

an elastic body having a hollowed dome-shaped contour

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

The highly porous nature of foam ensures a very high compliance and good conformity to the ear canal wall. The microscopic open porosity ensures that the impression material can be proper engaged by a large contact area

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Data Source

PatentEP3198890B1An impression-taking pad, a method of impression-taking, an impression, a method of manufacturing a custom ear canal shell
Publication Date: 2018.11.07 SONOVA AG
  • EP3198890B1 patent drawingFigure 1A~1C
  • EP3198890B1 patent drawingFigure 2~3
  • EP3198890B1 patent drawingFigure 4A~4B

AI summary

An impression-taking pad (10) is proposed used for impression-taking of an ear canal (26). Said impression-taking pad (10) comprises an elastic body (12) having a hollowed dome-shaped contour, wherein the inner surface (16) comprises axially aligned scallops (18).