Photoplethysmography Sensor Patch for Motion-Tolerant Signals
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Solution Overview
Problem
Existing photoplethysmography (PPG) sensing systems have large spatial profiles and high complexity, making them unsuitable for everyday wear and motion tolerance, and struggle with skin surface variations and anatomical issues, leading to unreliable biological signal readings.
Innovation Solution
A patch system with a silicon-based adhesive layer, acrylic-based adhesive layer, rigid support structure, and elastic spacer is used to maintain constant skin contact and apply pressure matching diastolic pressure, minimizing venous blood effects and enhancing PPG sensor performance on low perfusion anatomical sites.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If large sensing units with multiple arrays of light-emitting and light-detecting elements are used, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The sensing system is divided into discrete functional modules: a light source module (LED), a light detection module (photodetector), and a processing module. Each module performs a specific function, allowing the system to achieve accurate biological signal detection without requiring multiple complex arrays. The segmentation enables simplified design while maintaining measurement precision through dedicated functional components.
Solution Approach 2:
The sensing unit is designed as a universal platform that can detect multiple biological parameters (heart rate, oxygen saturation, blood pressure) using the same basic light source and photodetector configuration. This multi-functionality eliminates the need for separate specialized sensors for each parameter, reducing overall device complexity while maintaining measurement accuracy across different physiological measurements.
2Reliability
If large sensing footprints are used, then reliability is improved by compensating for skin surface variations, but area of stationary object increases
Solution Approach 1:
The patent applies local quality by concentrating sensing resources at the precise location where blood volume changes occur最深在 tissue interface. Rather than distributing sensors across a large area, the light source and photodetector are positioned to optimize penetration depth and detect signals from the specific anatomical region of interest, achieving reliable motion-tolerant measurement with minimal footprint.
Solution Approach 2:
The patent replaces mechanical coupling (physical contact pressure from large sensing areas) with optical field-based detection. By using light transmission and reflection principles, the system achieves motion tolerance through optical path stability rather than mechanical pressure distribution, enabling reliable measurement with a small, flexible sensing footprint that accommodates skin movement.
3Measurement precision
If multiple PPG arrays are used, then measurement precision is improved, but ease of manufacture decreases
Solution Approach 1:
The patent merges the light source and photodetector into a closely integrated sensing unit with fixed geometric relationships between components. This consolidation eliminates the need for separate calibration of multiple independent arrays, as the integrated design ensures consistent optical coupling and predictable light paths, greatly simplifying manufacturing while maintaining measurement precision through unified component alignment.
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 system provides motion-tolerant, low-profile PPG sensing with improved signal quality and accuracy, compatible with various skin tones and anatomical variations, suitable for continuous monitoring and diagnosis of conditions like sleep apnea.
Implementation Method 1
measuring an amount of light reflected and/or transmitted by the skin
Implementation Method 2
Photoplethysmography (PPG) generally refers to light-based techniques for detecting volumetric changes in blood
Implementation Method 3
an elastic spacer operatively connected to a first side of the PPG sensor
Implementation Method 4
a silicon-based adhesive layer... an acrylic-based adhesive layer
Data Source
AI summary
The present disclosure relates to devices and processes that produce superior photoplethysmography (PPG) signals. In various embodiments, the present devices and processes leverage load backing, conformal contact, and strain isolation mechanisms to produce higher quality and amplitude PPG signals, and provide more repeatable results than previous devices and processes. In at least one embodiment, the devices discussed herein include a rigid support structure and elastic spacer for supporting a PPG sensor and various adhesive layers.