Wrist-Worn Pulse Transit Time Sensor Using Multi-Modal Signal Fusion
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Solution Overview
Problem
Conventional cardiovascular monitoring methods are cumbersome and limited for continuous, non-clinical use, particularly for heart disease and hypertension management, as they require trained professionals and uncomfortable sensors, while wrist-worn devices are restricted to simple metrics like heart rate.
Innovation Solution
A wrist-worn device integrating a radial tonometer, electrodes, and a microphone to calculate pulse transit time by combining pressure, electrical, and audio signals, enabling comprehensive cardiovascular monitoring outside clinical settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional cardiovascular monitoring methods are used, then measurement precision is improved, but device complexity and ease of operation deteriorate due to requiring trained professionals and uncomfortable sensors
Solution Approach 1:
The patent segments the complex cardiovascular monitoring task into multiple simple sensor measurements (ECG electrodes, phonocardiogram microphone, photoplethysmography optical sensor, impedance cardiography electrodes) that can be automatically processed. This divides the professional-grade monitoring function into wearable consumer-friendly components that collectively achieve comprehensive cardiovascular assessment without requiring user expertise.
Solution Approach 2:
The wrist-worn device integrates multiple sensing modalities (electrical, acoustic, optical, impedance) into a single universal platform that can perform various cardiovascular measurements including pulse transit time, pre-ejection period, heart rate, and blood pressure estimation. This multi-functional approach replaces multiple specialized clinical devices with one versatile wearable system.
2Measurement precision
If conventional cardiovascular monitoring methods are used, then measurement precision is improved, but device complexity worsens due to requiring multiple uncomfortable sensors
Solution Approach 1:
The patent merges four distinct sensing technologies (ECG, phonocardiogram, photoplethysmography, and impedance cardiography) into a single integrated wrist-worn device. By combining these sensors and their signal processing functions into one unit, the system achieves comprehensive cardiovascular monitoring capability while simplifying the user experience to a single wearable device rather than multiple separate sensors.
Solution Approach 2:
The device serves as a universal cardiovascular monitoring platform that performs multiple measurement functions (pulse transit time, pre-ejection period, heart rate, blood pressure) through integrated sensors. This multi-functional design consolidates what would traditionally require several specialized clinical devices into one versatile wearable system.
3Ease of operation
If wrist-worn devices are used, then ease of operation is improved, but measurement precision deteriorates due to being limited to simple metrics like heart rate
Solution Approach 1:
The patent segments cardiovascular monitoring into multiple wearable sensor components (ECG electrodes on wrist and chest, phonocardiogram microphone, optical sensor, impedance electrodes) that can be worn comfortably and automatically processed. This segmentation enables complex measurements to be taken through simple wearable components without requiring user expertise in operation or interpretation.
Solution Approach 2:
The system measures multiple physiological parameters simultaneously (electrical signals from ECG, acoustic signals from heart valves via phonocardiogram, optical signals from blood volume changes, impedance changes from cardiac activity) and processes them to derive advanced metrics like pulse transit time and pre-ejection period. This multi-parameter approach transforms simple wearable measurements into comprehensive cardiovascular assessment.
4Measurement precision
If comprehensive cardiovascular monitoring is implemented, then measurement precision is improved, but ease of operation worsens due to requiring trained professionals
Solution Approach 1:
The wrist-worn device performs automated signal processing and cardiovascular metric calculation without requiring professional intervention. The system self-calibrates, automatically processes ECG, phonocardiogram, optical, and impedance signals to compute pulse transit time, pre-ejection period, and other cardiovascular metrics. This self-service capability enables comprehensive monitoring by consumers without trained professionals.
Solution Approach 2:
The device incorporates automated feedback loops that continuously monitor signal quality, adjust processing parameters, and validate measurements. The system provides real-time feedback on measurement validity and can guide users through proper sensor placement or signal optimization, eliminating the need for professional oversight while maintaining measurement accuracy.
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
Facilitates continuous, accurate cardiovascular monitoring with comprehensive metrics like pulse transit time and pulse wave velocity, enhancing preventative and diagnostic care without the need for trained professionals or uncomfortable sensors.
Implementation Method 1
a radial tonometer configured to output a pressure signal indicating a pulse pressure wave at a wearer's wrist
Implementation Method 2
two or more electrodes configured to output an electrical signal indicating a wearer's heart has been commanded to contract
Implementation Method 3
a microphone configured to output an audio signal indicating a closing of a wearer's aortic valve
Data Source
AI summary
A wrist-worn device heart-monitoring device is presented. The wrist-worn heart-monitoring device includes a radial tonometer configured to output a pressure signal indicating a pulse pressure wave at a user's wrist, two or more electrodes configured to output an electrical signal indicating a user's heart has been commanded to contract, and a microphone configured to output an audio signal indicating a closing of a user's aortic valve. The wrist-worn heart-monitoring device further includes a pulse transit time monitor configured to calculate a pre-ejection period of the user's heart based on at least the pressure, electrical, and audio signals, and calculate a pulse transit time based on at least the pre-ejection period, the pressure signal, and the electrical signal.