Wrist-Worn Blood Pressure Sensor Array with Adjustable Biasing
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Solution Overview
Problem
Current non-invasive blood pressure measurement methods, such as ambulatory and home monitoring, fail to provide continuous measurements and can disrupt sleep patterns due to intermittent cuff inflation and deflation, and face challenges in accurately identifying the ideal applanation location for radial artery tonometry, especially with varying human anatomy.
Innovation Solution
A wrist-worn device with a pressure sensor array and actuators that apply variable pressure to the radial artery, allowing for passive tracking and on-demand blood pressure measurements without periodic calibration, using a combination of piezoelectric and piezoresistive sensors to calculate absolute arterial pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If intermittent cuff inflation and deflation is used for ambulatory blood pressure measurement, then blood pressure can be measured periodically, but the person's sleeping pattern is disturbed and measurement continuity is lost
Solution Approach 1:
The patent replaces the mechanical oscillometric cuff system with an applanation tonometry system that uses a lightweight pressure sensor and adjustable biasing mechanism. This substitution eliminates the need for repeated cuff inflation/deflation while enabling continuous blood pressure measurement through passive arterial wall apposition, thereby avoiding sleep disturbance.
Solution Approach 2:
The invention implements continuous blood pressure measurement by maintaining constant contact between the pressure sensor and the radial artery through an adjustable biasing mechanism. Unlike intermittent cuff-based methods, this system provides uninterrupted monitoring by continuously apposing the sensor to the artery, enabling real-time detection of blood pressure variations without disrupting the subject's normal activities or sleep patterns.
2Duration of action of stationary object
If applanation tonometry is used for blood pressure measurement, then continuous non-invasive measurement is enabled, but accurate identification of ideal applanation location is challenging due to varying human anatomy
Solution Approach 1:
The system employs an adjustable biasing mechanism that dynamically adapts to different anatomical variations among subjects. The biasing force can be modified to compensate for differences in radial artery depth, wrist anatomy, and tissue characteristics, enabling reliable applanation and continuous measurement across diverse human anatomies without requiring precise pre-identification of the ideal sensor location.
Solution Approach 2:
The applanation tonometry system performs self-alignment and self-adjustment through the adjustable biasing mechanism, which automatically adapts to the subject's specific anatomy. This eliminates the need for operator skill in locating the ideal applanation point, as the system self-regulates the sensor position and pressure to achieve optimal measurement conditions regardless of anatomical variations.
3Ease of operation
If traditional oscillometric cuff methods are used for ambulatory measurement, then blood pressure can be measured, but the measurement is not continuous and requires periodic intervention
Solution Approach 1:
The invention transforms the measurement process from periodic to continuous by maintaining constant sensor-apparatus contact with the radial artery through an adjustable biasing mechanism. This enables uninterrupted blood pressure monitoring throughout the measurement period, eliminating the gaps between periodic measurements and providing continuous data streams for comprehensive blood pressure assessment.
Solution Approach 2:
The system replaces the active mechanical cuff inflation/deflation mechanism with a passive applanation tonometry approach using a lightweight sensor and adjustable biasing system. This substitution enables continuous measurement without requiring periodic operator intervention or complex mechanical actuation, thereby maintaining ease of operation while achieving measurement continuity.
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
Enables continuous, non-invasive, and convenient blood pressure monitoring without disrupting daily activities or requiring trained assistance, improving accuracy and user experience by identifying the optimal sensor location and reducing signal processing complexity.
Implementation Method 1
A piezoelectric film or piezoresistive pressure sensor may be coupled to a distal face of the fluid bladder to measure a pressure at the wrist
Implementation Method 2
A piezoelectric film or piezoresistive pressure sensor may be coupled to a distal face of the fluid bladder to measure a pressure at the wrist
Data Source
AI summary
The present invention generally relates to blood pressure monitoring. In some embodiments, methods and devices of measuring a mean arterial pressure are provided and/or monitoring blood pressure changes. A wrist-worn device may include a plurality of sensors backed by a plurality of actuators. Subsets of the plurality of sensors may be selectively actuateable against a wrist of a user using one or more of the plurality of actuators. A preferred sensor and location may be identified based on pressure signals received from each of the sensors. In some embodiments, devices may use a fluid bladder coupled with piezoelectric film sensors. A fluid bladder pressure sensor may be used to calibrate the piezoelectric film signal to provide a static and dynamic pressure reading. In yet another embodiment, a mean arterial pressure may be calculated by processing a swept pressure signal obtained as a sensor is swept through different heights.