Hearing Device Dome for Optical Isolation
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Solution Overview
Problem
Hearing devices with integrated PPG sensors face challenges in reliable measurement due to insufficient optical isolation between the light source and photodetector, leading to noise interference from ambient light and increased complexity and power consumption.
Innovation Solution
A hearing device design featuring a dome that conforms to the ear canal shape, separating the light source and photodetector output, with the dome absorbing or reflecting emitted light to reduce noise and complexity, and utilizing a light guide to direct light to the photodetector, thereby improving measurement reliability and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the light source and photodetector are placed close together in a standard hearing device, then the device complexity and power consumption are reduced, but optical isolation is insufficient leading to unreliable measurements due to ambient light interference
Solution Approach 1:
The dome is nested within the hearing device housing, creating a contained optical isolation structure that integrates the light source, photodetector, and shielding elements into a compact unified assembly, resolving the contradiction between reliable measurement and device complexity
Solution Approach 2:
The dome acts as an intermediary structure between the light source and external environment, using its light-absorbing and light-reflecting properties to block ambient light from reaching the photodetector, thereby improving measurement reliability without requiring complex external shielding
2Reliability
If the light source and photodetector are placed close together, then the device complexity and power consumption are reduced, but ambient light from the environment interferes with the detector causing noise
Solution Approach 1:
The dome serves as an intermediary optical barrier between the external ambient light environment and the photodetector, absorbing and reflecting incident light to prevent it from reaching the detector, thereby eliminating ambient light interference while maintaining device compactness
Solution Approach 2:
The harmful ambient light is effectively extracted or removed from the optical path reaching the photodetector through the dome's light-blocking properties, allowing the sensor to operate reliably without external light interference
3Measurement precision
If a strong light source is used to compensate for light attenuation over long paths, then acceptable physiological signal can be extracted, but power consumption and system complexity increase
Solution Approach 1:
The dome modifies the optical parameters by absorbing and reflecting light, creating a controlled optical environment that enhances the intensity and quality of light reaching the photodetector through tissue, thereby improving physiological signal extraction without requiring increased light source power
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 measurement reliability and reduces the complexity and power consumption of the optical detection circuitry by optimizing the placement and isolation of the light source and photodetector within the ear canal.
Implementation Method 1
the dome absorbs and/or reflects at least part of the emitted light such that an intensity of the emitted light at a wavelength passing through the dome to the photodetector is significantly smaller
Implementation Method 2
the dome absorbs and/or reflects at least part of the emitted light
Implementation Method 3
a photodetector configured to detect the emitted light after interacting with tissue of a subject
Data Source
Figure 1
Figure 2
Figure 3A~3D
AI summary
A hearing device includes a light source (212, 300, 304, 308, 402) configured to emit light, a photodetector (214, 404) configured to detect the emitted light after the emitted light passes through tissue of a subject; an audio receiver (116, 202) configured to deliver a sound to the subject, and a dome (120, 206) configured to conform to a shape of a subj ect's ear canal when the hearing device is in the ear canal. An output of the light source (212, 300, 304, 308, 402) and an input of the photodetector (214, 404) are separated by the dome (120, 206), and the dome (120, 206) absorbs and/or reflects at least part of the emitted light.