Cuff-less Blood Pressure Measurement via Finger PPG and Pressure Sensing
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Solution Overview
Problem
Current methods for blood pressure monitoring, especially in low-resource settings, lack ubiquitous and reliable cuff-less solutions due to the need for invasive procedures, skilled operators, or expensive equipment, and existing cuff-less technologies face accuracy issues from confounding physiology and calibration requirements.
Innovation Solution
A mobile device with a photoplethysmography (PPG) sensor and pressure sensor, guided by visual indicators and algorithms, allows users to apply pressure to their finger to measure blood volume oscillations, estimating blood pressure without a cuff, using a smartphone or similar device to miniaturize the necessary hardware and simplify the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If catheterization is used to measure blood pressure waveform, then measurement accuracy is improved, but the method becomes invasive
Solution Approach 1:
The patent uses an optical intermediary (light) to measure blood volume changes in the finger without direct blood contact. The PPG sensor detects blood volume oscillations through light absorption changes, providing non-invasive measurement while maintaining accuracy by measuring the actual blood volume waveform rather than relying on pressure transduction through tissue
Solution Approach 2:
The patent replaces the mechanical catheter-based pressure measurement system with an optical measurement system. Instead of mechanically inserting a catheter into the blood vessel to directly measure pressure, the system uses optical detection of blood volume changes to infer blood pressure information non-invasively
2Object-affected harmful factors
If auscultation method is used to measure blood pressure, then non-invasive measurement is achieved, but skilled operator is required
Solution Approach 1:
The system enables self-measurement of blood pressure by the user. The mobile device with PPG sensor and pressure sensor allows the user to independently measure their own blood pressure without requiring a skilled medical operator, making the measurement process accessible to anyone with the device
Solution Approach 2:
The patent replaces the acoustic auscultation method (requiring stethoscope and skilled operator to listen to Korotkoff sounds) with electronic sensing using PPG and pressure sensors that automatically detect blood pressure through blood volume oscillations, eliminating the need for skilled operators
3Extent of automation
If oscillometry method is used to measure blood pressure, then automatic measurement is achieved, but cuff and expensive equipment are required
Solution Approach 1:
The patent segments the traditional cuff-based oscillometry system into separate functional components: the pressure application function is separated from the measurement function. The user's finger applies pressure naturally while the mobile device independently performs the oscillation detection and blood pressure calculation, eliminating the need for an integrated cuff device
Solution Approach 2:
The patent extracts the measurement function from the cuff apparatus. Instead of requiring a cuff to both apply pressure and detect oscillations, the system uses the user's finger for pressure application and a separate mobile device with PPG sensor for oscillation detection, removing the complex cuff equipment requirement
4Object-affected harmful factors
If volume clamping method is used to measure finger blood pressure waveform, then non-invasive automatic measurement is achieved, but cuff and photoplethysmography sensor are required
Solution Approach 1:
The patent extracts the pressure application function from the specialized volume clamping cuff. Instead of using a cuff with built-in PPG sensor, the system uses the user's finger for pressure application and a separate mobile device with PPG sensor for blood volume measurement, eliminating the need for the complex integrated cuff-sensor device
Solution Approach 2:
The mobile device serves multiple functions: it acts as both the pressure sensor (detecting finger pressure) and the blood volume sensor (PPG detection), replacing the need for separate cuff and sensor components required by volume clamping methodology
5Ease of operation
If pulse transit time method is used for cuff-less blood pressure monitoring, then passive monitoring is achieved, but accuracy deteriorates due to confounding physiology
Solution Approach 1:
The patent replaces the pulse transit time method (which measures time delay between arterial sites) with direct blood volume oscillation measurement. By using PPG to detect actual blood volume changes in the finger and correlating with pressure, the system directly measures blood pressure physiology rather than inferring from timing differences, eliminating confounding physiological effects
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
This approach provides a user-friendly, cost-effective, and accurate method for cuff-less blood pressure monitoring, enabling continuous hypertension management and improving detection and control rates, especially in resource-constrained environments.
Implementation Method 1
measuring, by the sensing unit, blood volume oscillations in the finger
Implementation Method 2
measuring, by the sensing unit, pressure applied to the sensing unit
Data Source
Figure 1
Figure 2A~2B
Figure 2C
AI summary
A method is presented for measuring blood pressure using a device includes guiding a user regarding placement of a finger in relation to a sensing unit. The method includes measuring, by the sensing unit, a pressure applied to the sensing unit and measuring, by the sensing unit, blood volume oscillations in the finger while pressure is being applied to the sensing unit by the finger. The method further includes estimating, by a computer processor of the device, a blood pressure value for the user from the measured pressure and the measured blood volume oscillations. The method also includes presenting the blood pressure value.