Cuffless Blood Pressure Sensing Using Dual Pulse-Wave Measurements
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing blood pressure measurement devices require compression of the limb for arterial occlusion, which is uncomfortable and unsuitable for continuous monitoring, and cuffless methods are complex or require additional measurements like ECG.
Innovation Solution
A method using two sensors to measure a parameter following a monotonic variation during systole at different distances from the heart, comparing characteristics, and applying a calibration model to estimate blood pressure without limb compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a compression cuff is used to achieve arterial occlusion for blood pressure measurement, then measurement accuracy is improved, but user comfort deteriorates and continuous monitoring becomes unacceptable
Solution Approach 1:
The invention extracts and eliminates the compression cuff component from the blood pressure measurement system. Instead of using a cuff to occlude the artery, the patent uses a tonometric sensor that directly contacts the skin to detect pulse wave characteristics, thereby removing the source of discomfort while maintaining measurement capability through alternative physical principles
Solution Approach 2:
The invention replaces the mechanical compression system with an optical detection system. The tonometric sensor uses photodetectors to detect light absorption changes caused by blood volume variations during pulse waves, substituting mechanical compression with optical measurement to achieve blood pressure data without limb compression
2Ease of operation
If cuffless blood pressure measurement methods are used to improve comfort, then user comfort is improved, but device complexity increases due to requirements for multiple sensors and synchronization
Solution Approach 1:
The invention merges the functions of multiple sensors into a single integrated tonometric sensor unit. The sensor combines photodetectors for light detection, acceleration sensors for motion detection, and temperature sensors into one compact device, simplifying the overall system architecture while maintaining the capability to detect pulse wave characteristics without compression
Solution Approach 2:
The tonometric sensor is designed with multi-functionality, serving as both a photoplethysmography (PPG) sensor for detecting blood volume changes and an acceleration sensor for detecting body motion. This universal sensor design reduces the total number of components needed and simplifies the measurement system while improving comfort
3Duration of action of moving object
If pulse wave velocity measurement is used for blood pressure estimation, then continuous monitoring capability is improved, but temporal synchronization requirements increase system complexity
Solution Approach 1:
The system uses the body's own motion signals, detected by the acceleration sensor, to automatically synchronize and identify corresponding pulse waves between different measurement locations. This self-service approach eliminates the need for external synchronization systems like ECG, as the body's natural motion provides the reference signal for temporal 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
Enables continuous, comfortable blood pressure monitoring using compact devices without the need for compression, leveraging the difference in systolic rise times and slopes at different body locations.
Implementation Method 1
an intensity of light backscattered or transmitted by an artery
Implementation Method 2
an intensity of an acoustic wave reflected by an artery
Implementation Method 3
a vibration induced by systole
Implementation Method 4
an electrical impedance induced by systole
Data Source
Figure 1A~1C
Figure 2~3
Figure 4~5A
AI summary
Method for determining a user's blood pressure by measuring a parameter following a monotonic variation during a systole, the method comprising: - a) during at least one cardiac cycle, proximal measurement (110) of the parameter at a first distance from the heart and distal measurement (120) of the parameter at a second distance from the heart, the second distance being greater than the first distance; - b) from each measurement, estimation (130) of a characteristic representative of the variation of the parameter during systole at each distance; - c) comparison (140) of each characteristic (VDMS); - d) determination (150) of the blood pressure (MAP) as a function of the comparison resulting from step c), using a calibration model.