Asymmetric Earpiece Retention Structure for PPG Sensor Stability
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Solution Overview
Problem
Current in-canal hearing aid receivers with PPG sensors face issues with signal quality due to inadequate contact and angulation caused by motion, which is not effectively addressed by symmetric designs, leading to compromised PPG sensor performance.
Innovation Solution
An earpiece with a retention structure on the lateral wall of the housing that stabilizes the device in the ear canal without obstructing the sensor, featuring a waveguide and asymmetrical design to ensure optimal contact and light penetration, allowing for improved signal quality and motion tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a symmetric dome is used to secure the RIC in the ear canal, then the device is easy to manufacture and install, but the sensor contact with tissue is insufficient and angulation occurs during motion
Solution Approach 1:
The patent applies asymmetry by providing a retention structure with an asymmetric cross-sectional shape that conforms to the natural asymmetric geometry of the ear canal. This asymmetric design enables consistent contact between the sensor and ear canal tissue while preventing rotation and angulation during user motion, thereby improving PPG signal quality without compromising manufacturing ease
Solution Approach 2:
The retention structure is designed with local quality variations, featuring different surface characteristics and geometric properties at different locations to optimize both sensor contact and structural stability. The asymmetric cross-section provides enhanced contact at specific zones while maintaining overall device stability
2Measurement precision
If custom made hearing aid shells are produced to improve sensor contact, then PPG sensor quality is significantly improved, but production cost increases and user convenience decreases
Solution Approach 1:
The patent applies universality by designing a retention structure that provides customized-fit benefits for multiple users through a standardized asymmetric geometry. This universal asymmetric design conforms to the general asymmetric shape of human ear canals, enabling improved sensor contact across diverse users without requiring individual customization, thereby reducing production costs and enhancing user convenience
3Stability of the object's composition
If the retention structure is placed close to the sensor, then stabilization is improved, but the sensing element may be obstructed
Solution Approach 1:
The patent applies dimensionality change by resolving the spatial conflict between retention structure and sensor through asymmetric positioning in multiple dimensions. The retention structure is strategically placed at a distance along the longitudinal axis while maintaining lateral proximity, creating optimal stabilization without obstructing the optical path of the sensor
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 enhanced PPG sensor signal quality by maintaining consistent contact with the ear canal tissue, reducing motion-induced angulation, and allowing for mass production while maintaining cost efficiency and user convenience.
Implementation Method 1
the retention structure may comprise a waveguide at the position of the sensing element
Data Source
Figure 1A~1B
Figure 2~3
Figure 4~5
AI summary
The invention relates to an earpiece for a hearing device configured to be inserted into an ear canal (8) of a user, the earpiece comprising a housing (1) with a medial end having a sound outlet port (4), the housing (1) accommodating a receiver (20) configured to reproduce sound into the ear canal through the sound outlet port (4), the earpiece further comprising a sensor (2) with a sensing element (11, 12) located on or in a lateral wall of the housing (1), and a retention structure (3) arranged on the housing (1) to stabilize the position of the housing (1) in the ear canal (8) without obstructing the sensing element (2).