Cuffless Blood Pressure Measurement via Touch Force and PPG
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Solution Overview
Problem
Existing cuff-based blood pressure measurement methods are non-continuous, difficult to integrate into portable devices, and suffer from inaccuracies due to noise vulnerability and the need for multiple signal measurements, while cuffless methods like PTT and PWA have limitations in accuracy and device compactness.
Innovation Solution
A touch-type blood pressure measurement apparatus using a touch sensor, PPG sensor, and force sensor to generate contact area and pressure signals, with a controller that calculates blood pressure based on these signals, correcting for noise and improving accuracy through contact pressure profiling and user-specific adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pressurized cuff-based method is used for blood pressure measurement, then measurement accuracy is improved, but device portability and compactness deteriorate due to the pressurizing pump configuration
Solution Approach 1:
The patent extracts and removes the pressurizing pump and cuff components from the blood pressure measurement system, replacing them with a touch-type sensor that directly contacts the finger. This eliminates the bulky mechanical pressurization system while maintaining measurement capability through alternative physical principles (touch force and PPG signal correlation).
Solution Approach 2:
The patent replaces the mechanical pressurization system with an optical-electrical sensing system. Instead of using a mechanical pump to inflate a cuff, the system uses a touch sensor to detect finger contact force and a PPG sensor to detect blood volume changes, substituting mechanical action with optical and electrical measurement methods.
2Volume of moving object
If PTT method is used for cuffless blood pressure measurement, then device compactness is improved, but measurement accuracy deteriorates due to the need for multiple position measurements and individual correction
Solution Approach 1:
The patent merges multiple measurement functions into a single integrated sensor assembly. The touch sensor and PPG sensor are positioned adjacently to simultaneously measure touch force and blood volume changes at the same location, eliminating the need for separate measurements at multiple positions required by PTT methods.
Solution Approach 2:
The system uses the user's own finger as both the measurement target and the measurement tool. The finger provides both the PPG signal source and the touch force application, eliminating the need for external correction factors based on individual anatomical variations that PTT methods require.
3Device complexity
If PWA method is used for cuffless blood pressure measurement, then device simplicity is improved, but measurement accuracy deteriorates due to noise vulnerability
Solution Approach 1:
The patent introduces touch force as an intermediary variable that mediates between the PPG signal and blood pressure calculation. The touch force signal serves as a reference that correlates with blood pressure changes, providing a stable baseline that reduces noise vulnerability and improves measurement accuracy compared to PWA methods that rely solely on PPG waveform analysis.
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 accurate, cuffless blood pressure measurement in a portable and compact form, resistant to noise and user-specific variations, providing reliable blood pressure readings.
Implementation Method 1
at least one photoplethysmogram (PPG) sensor configured to generate a PPG signal of the user while the finger is in contact with the touch sensor
Implementation Method 2
a touch sensor configured to generate a contact area signal when a finger of a user is in contact with the touch sensor
Implementation Method 3
a force sensor configured to generate a touch force signal of the finger in contact with the touch sensor
Data Source
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AI summary
A touch-type blood pressure measurement apparatus is provided. The touch-type blood pressure measurement apparatus comprises a touch sensor configured to generate a contact area signal indicating a size of a contact area between the touch sensor and a finger of a user, when the finger of the user is in contact with the touch sensor. The touch-type blood pressure measurement apparatus comprises further at least one photoplethysmogram (PPG) sensor configured to generate a PPG signal of the user while the finger is in contact with the touch sensor, a force sensor provided separately from the touch sensor and configured to generate a touch force signal of the finger in contact with the touch sensor, the touch force signal comprising a value of a force exerted by the finger to the force sensor, and a controller configured to determine a contact pressure based on the size of the contact area and the value of the force, and obtain a blood pressure of the user based on a change of the PPG signal according to the contact pressure, wherein the at least one PPG sensor is disposed between the touch sensor and the force sensor in a vertical direction of the touch-type blood pressure measurement apparatus.