Earpiece Cradle Limits Sensor Field-of-View for Pulse Monitoring
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Solution Overview
Problem
Existing earphones with physiological monitoring functions are not suited for long-term wear due to the need for a tight fit to avoid ambient light noise, which restricts blood flow and causes discomfort.
Innovation Solution
The design includes a nozzle with a cradle for the sensor and emitter, limiting their field-of-view to reduce ambient light detection, allowing for a looser fit and improved comfort during extended wear, and using a processor with reduced processing power to minimize noise and heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the earphone is fitted tightly against the ear canal to prevent ambient light from reaching the sensor, then the measurement precision of pulse monitoring is improved, but the blood flow in the ear canal tissue is restricted causing user discomfort
Solution Approach 1:
The sensor field of view is segmented into different angular zones using the cradle structure. The cradle creates a physical barrier that blocks light from specific angles (ambient light from surroundings) while allowing light from other angles (transmitted through tissue) to reach the sensor. This angular segmentation resolves the contradiction by filtering harmful light paths without requiring tight mechanical fit.
Solution Approach 2:
The cradle structure provides localized light blocking properties at specific angular positions around the sensor, rather than requiring uniform tight contact over the entire ear canal surface. This local quality approach blocks ambient light from predetermined undesirable angles while leaving other areas open, maintaining blood flow and comfort while achieving measurement precision.
2Measurement precision
If a tight fit is used to block ambient light, then the signal-to-noise ratio is improved, but the wearability and duration of use are reduced
Solution Approach 1:
The cradle segments the sensor's angular field of view to selectively block ambient light from specific directions while allowing transmitted light to pass. This angular segmentation achieves signal-to-noise improvement without requiring sustained tight mechanical pressure, enabling longer wear times.
Solution Approach 2:
The cradle acts as an intermediary structure between the sensor and the ambient environment. It provides passive geometric blocking of harmful light angles without requiring active user adjustment or tight fit maintenance, allowing the device to be worn comfortably for extended periods while maintaining signal quality.
3Measurement precision
If the sensor field-of-view is narrowed using a cradle, then the detection of ambient light is reduced, but the device complexity increases
Solution Approach 1:
The cradle is implemented as a thin, simple structural element that provides angular light blocking functionality. This thin-film approach achieves ambient light rejection through geometric design rather than complex optical components, minimizing the increase in device complexity while improving measurement precision.
4Temperature
If a processor with reduced processing power is used, then the heat generation is reduced, but the ability to filter noise from ambient light is diminished
Solution Approach 1:
The cradle performs preliminary physical filtering of ambient light before the light reaches the sensor. By blocking harmful angles in advance, the optical signal reaching the sensor already has reduced noise components, minimizing the computational processing needed for noise filtering and thereby reducing heat generation from the processor.
Solution Approach 2:
The mechanical cradle structure substitutes for computational noise filtering methods. Instead of relying on the processor to algorithmically remove ambient light noise, the physical cradle geometry pre-filters the light optically, reducing the computational burden and heat generation while maintaining measurement precision.
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
This design enhances the accuracy of physiological monitoring by reducing noise and discomfort, enabling longer-term wear without compromising data quality, and is suitable for both earphones and hearing aids.
Implementation Method 1
the emitters emit light in a frequency which can be absorbed by blood in the tissue of the ear canal
Implementation Method 2
Some of the light emitted by the emitters penetrates through the skin and tissue of the ear canal and, by being scattered within the ear tissue, is able to emerge from the tissue to be detected by the sensor
Implementation Method 3
The cradle limits the field-of-view of the sensor, and this protects the sensor from detecting light which reaches the sensor from a predetermined, undesirable angle
Data Source
AI summary
An earpiece comprising a sensor for detecting light in the ear canal. The sensor is held in a cradle to reduce field-of-view. The reduced field-of-view reduce the possibility of light reaching the sensor in a tangential angle. Therefore, the chance of ambient light and light from an emitter reaching the sensor directly is reduced. This improves the likelihood that the readings of the sensor has a greater portion from light that has travelled through the tissue of the ear canal than not.