In-Canal Earpiece Structure for Stable PPG Sensor Contact
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Solution Overview
Problem
Existing in-canal hearing aids with integrated PPG sensors face issues of motion tolerance and suboptimal signal quality due to flexible sensor placement and distance from the skin, leading to interference from environmental light and reduced physiological measurement accuracy.
Innovation Solution
An earpiece design with a customizable shell and support element that securely holds a flexible printed circuit board and sensor, featuring aligned windows and recesses for optimal sensor placement, ensuring consistent contact with the ear canal and minimizing environmental interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a flexible dome is used to hold the sensor in the ear canal, then comfort is improved, but motion tolerance and signal quality deteriorate
Solution Approach 1:
The device is divided into two functional parts: a flexible dome for comfort and a rigid sensor housing for stable sensor placement. The sensor housing contains the PPG sensor and is positioned against the ear canal wall, while the flexible dome provides comfort during wear. This segmentation allows each part to fulfill its specific function without compromising the other.
Solution Approach 2:
A rigid sensor housing acts as an intermediary between the flexible dome and the sensor components. This housing provides a stable platform for the PPG sensor, preventing direct motion between the sensor and the ear canal wall, while still allowing the flexible dome to provide comfort. The intermediary structure isolates the sensor from harmful motions.
2Ease of manufacture
If the sensor is placed at a distance from the skin, then ease of integration is improved, but signal quality deteriorates due to reflections and environmental light interference
Solution Approach 1:
The sensor housing extends in the longitudinal dimension of the ear canal, allowing the PPG sensor to be positioned close to the ear canal wall while maintaining proper optical alignment. This dimensional arrangement enables the sensor to achieve optimal measurement conditions without complicating the integration process.
Solution Approach 2:
The rigid sensor housing pre-establishes a stable geometric relationship between the PPG sensor and the ear canal wall, preventing future misalignment due to motion or deformation. This preliminary structural constraint ensures consistent sensor-to-skin contact and blocks environmental light from reaching the photodetector, thereby preventing signal degradation before it can occur.
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
Enhances sensor signal quality and motion tolerance, allowing for precise physiological measurements by maintaining consistent contact and reducing interference, while being customizable for individual ear canals for improved fit and comfort.
Implementation Method 1
an optical photoplethysmographic sensor (PPG) is used to measures changes in microvascular blood volume, to further extract vital signs
Implementation Method 2
the photoreceptor being configured to detect light directed toward the housing
Data Source
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AI summary
The invention relates to an earpiece (10) for a hearing device, the earpiece (10) being configured to be at least partially inserted into an ear canal of a user, the earpiece (10) comprising: - a shell (11), - a receiver (15) configured to reproduce sound into the ear canal through a sound outlet port (16), - a flexible printed circuit board (12) facing an inner surface (32) of the shell (11), the flexible printed circuit board (12) comprising at least one sensor (13), - a support element (14) having an outer surface (34) shaped complementary to the inner surface (32) of the shell (11) near the medial end thereof, wherein the outer surface (34) of the support element (14) and/or the inner surface (32) of the shell (11) has a recess (18) configured to accommodate the printed circuit board (12) or a part thereof carrying the at least one sensor (13), wherein the shell (11) has one or more windows (31.1, 31.2) aligned with the one or more sensor (13) and/or components (13.1, 13.2) thereof on the flexible printed circuit board (12), wherein the support element (14) has a through-hole (19) with a seat (20) for the receiver (15).