Optical Pulse-Rate Sensor Pillow Assembly for Stable Skin Contact
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Solution Overview
Problem
Wearable electronic devices face challenges in maintaining sensors in close contact with the skin due to wrist movement and varying wrist shapes and sizes, affecting the accuracy of measurements such as heart rate monitoring.
Innovation Solution
The use of a ring-shaped electrically-conductive skin sensor supported by a pillow assembly with a rolling diaphragm and spring mechanism to maintain constant contact with the skin, along with an optical pulse-rate sensor positioned on the pillow mound, ensures accurate measurements even during vigorous movement, and an elevated rim to prevent ambient light noise and capillary compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sensor is placed directly on the wearable device surface, then the device structure is simple, but the sensor cannot maintain constant contact with the skin during wrist movement
Solution Approach 1:
The patent employs a dynamic pillow assembly that can deform and adapt its shape to maintain sensor-skin contact. The pillow includes a deformable body with rolling elements that move in response to wrist motion, ensuring the optical sensor remains in constant contact with the skin surface despite dynamic movement conditions.
Solution Approach 2:
The pillow assembly serves as an intermediary element between the rigid wearable device structure and the flexible skin surface. It mediates the mechanical interaction by providing a compliant interface that absorbs movement discrepancies while maintaining stable sensor contact through its deformable geometry.
2Measurement precision
If the optical pulse-rate sensor is positioned close to the skin, then measurement accuracy improves, but ambient light noise and capillary compression increase
Solution Approach 1:
The patent implements localized structural features including an elevated rim that creates a controlled microenvironment around the optical sensor. This rim structure selectively manages light exposure and pressure distribution at the sensor location, allowing close skin contact for accurate measurement while blocking ambient light and preventing capillary compression in specific zones.
Solution Approach 2:
The pillow assembly is segmented into functional zones: a contact region for sensor-skin interface, an elevated rim region for light shielding and pressure control, and a rolling element region for maintaining contact stability. This segmentation allows each zone to address specific requirements without compromising overall performance.
3Reliability
If the sensor maintains constant contact with the skin during vigorous movement, then measurement reliability improves, but the device must accommodate varying wrist shapes and sizes
Solution Approach 1:
The patent utilizes a flexible pillow assembly with thin-walled deformable structures that can conform to various wrist geometries. The pillow material and structure are designed to be compliant and adaptable, allowing the same device to maintain stable sensor contact across different user anatomies and movement conditions through elastic deformation and shape adaptation.
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 configuration enhances the effectiveness of sensors by maintaining consistent contact with the skin, improving measurement accuracy and reducing noise interference, especially during physical activity.
Implementation Method 1
The pillow may include a rolling diaphragm and/or spring to independently suspend the optical pulse-rate sensor so that it maintains constant near contact with the wearer's skin
Implementation Method 2
The pillow may include a rolling diaphragm and/or spring to independently suspend the optical pulse-rate sensor
Implementation Method 3
an optical pulse-rate sensor positioned on the pillow mound
Implementation Method 4
an optical pulse-rate sensor positioned on the pillow mound
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A sensory-and-logic system comprises an illumination source configured to emit a blood-sensing light, a window through which the blood-sensing light passes en route to human tissue, an illumination receiver configured to measure the blood-sensing light reflected back through the window from the human tissue, a frame surrounding the window and elevating away from the window, and a pillow surrounding the frame and recessing from the frame and the window.