Finger Pulse Pressure Sensing for Cuffless Absolute Blood Pressure
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Solution Overview
Problem
Conventional blood pressure measurement techniques using inflatable cuffs are inconvenient, prone to inaccuracies, and require electromechanical actuators, leading to high power consumption, slow measurement times, and a high risk of component failure.
Innovation Solution
Measurements of blood volume pulses in a finger are combined with force and pressure applied against a finger abutment surface to determine absolute blood pressure values without a pump or electromechanical actuator, using bioimpedance sensors and other sensors to sense blood volume pulses and pressure/force, allowing for concurrent and time-resolved measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional cuff-based blood pressure measurement techniques are used, then blood pressure can be measured, but the measurement process is inconvenient, prone to inaccuracies, and requires electromechanical actuators leading to high power consumption and slow measurement times
Solution Approach 1:
The patent removes the cuff and electromechanical actuator from the blood pressure measurement system. Instead of using a cuff that needs to be inflated and deflated by a pump, the invention uses a finger-pressed sensor that directly measures blood pressure through optical detection of blood volume changes, eliminating the need for complex mechanical components and reducing power consumption
Solution Approach 2:
The patent replaces the mechanical cuff-inflation system with an optical measurement system. The sensor detects blood volume pulses optically through the finger, substituting mechanical actuation with optical detection to achieve blood pressure measurement without moving parts or high power consumption
2Reliability
If electromechanical actuators are used for cuff inflation, then blood pressure measurement can be performed, but the risk of component failure increases and measurement speed decreases
Solution Approach 1:
The patent extracts and removes the electromechanical actuator (pump) from the system entirely. The blood pressure measurement is achieved through direct optical sensing of blood volume changes in the finger, eliminating components that can fail and enabling instantaneous measurement without inflation/deflation cycles
Solution Approach 2:
The finger itself serves as the measurement medium, utilizing the natural blood flow and blood volume changes in the finger tissue. The user's own finger provides the optical path and physiological signal, eliminating the need for external mechanical actuation and reducing system complexity
3Measurement precision
If conventional cuff-based techniques are used, then blood pressure measurement is possible, but incorrect cuff positioning leads to measurement inaccuracies
Solution Approach 1:
The finger automatically positions itself on the sensor surface, and the sensor adapts to the finger's natural placement. There is no cuff to position incorrectly - the measurement occurs where the finger naturally contacts the sensor, eliminating positioning errors while maintaining measurement accuracy
Solution Approach 2:
The sensor surface serves multiple functions: it provides the optical detection path, defines the measurement location, and adapts to natural finger placement. This multi-functionality eliminates the separate cuff component that requires precise positioning, as the sensor itself handles both detection and positioning guidance
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 method provides accurate, convenient, and efficient blood pressure measurements with reduced power consumption and minimal risk of component failure, enabling calibration with PTT-based techniques for relative changes.
Implementation Method 1
The first sensor 21 may comprise a bioimpedance sensor
Implementation Method 2
The first sensor 21 may comprise a photoplethysmography, PPG, sensor
Implementation Method 3
a second sensor 22 operative to sense a force or pressure with which the finger may be pressed on the finger abutment surface 24
Data Source
AI summary
A sensor device or system for performing a blood pressure measurement comprises a finger abutment surface, a first sensor operative to sense blood volume pulses in a finger pressed on the finger abutment surface, a second sensor operative to sense a force or pressure with which the finger is pressed on the finger abutment surface, and processing circuitry operative to process amplitudes of the sensed blood volume pulses and the sensed force or pressure with which the finger is pressed on the finger abutment surface to determine an absolute blood pressure.