Cuffless Blood Pressure Apparatus Using Contact Force Feedback
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Solution Overview
Problem
Current cuffless blood pressure measurement technologies face challenges in accuracy and compactness, with Pulse Transit Time methods requiring user-specific corrections and Pulse Wave Analysis being prone to noise and inaccurate due to non-continuous measurements.
Innovation Solution
A blood pressure measuring apparatus comprising a pulse wave measurer with first and second light sources, a photodetector, and a processor that adjusts light emission based on contact force to estimate blood pressure, ensuring improved accuracy and compactness by controlling light amount and blinking speed in response to measured contact force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If Pulse Transit Time (PTT) method is used for cuffless blood pressure measurement, then blood pressure can be measured without a cuff, but the apparatus cannot be manufactured in a compact size and requires correction for each user
Solution Approach 1:
The apparatus segments the measurement process into two distinct phases: a first measurement phase using infrared light to obtain pulse wave signals, and a second measurement phase using visible light to guide contact force application. This segmentation allows the system to achieve accurate blood pressure measurement without requiring a large cuff-based mechanism while eliminating the need for complex user-specific corrections by using the contact force feedback loop
Solution Approach 2:
The visible light source acts as an intermediary between the measurement system and the user. By providing visual feedback (light emission or blinking) based on measured contact force, the system guides the user to apply the appropriate force without requiring complex instructions or calibration procedures, thus achieving compact size while maintaining measurement accuracy
2Ease of operation
If Pulse Wave Analysis (PWA) is used for cuffless blood pressure measurement, then blood pressure can be measured without a cuff, but the measurement is vulnerable to noise and inaccurate
Solution Approach 1:
The apparatus continuously monitors contact force during the measurement process and provides real-time visual feedback to the user. This continuous adjustment ensures that the optimal contact force is maintained throughout the measurement, eliminating noise and inaccuracies that would occur with non-continuous or static force application
Solution Approach 2:
The system implements a feedback loop where the measured contact force is used to control the visible light source, which in turn guides the user to adjust their applied force. This feedback mechanism ensures that the contact force remains within the optimal range for accurate pulse wave analysis, significantly improving measurement precision by reducing noise
3Ease of operation
If visible light is used to guide contact force application, then user guidance is improved, but energy consumption increases
Solution Approach 1:
The visible light source operates periodically rather than continuously, emitting light or blinking based on the measured contact force and comparison with target force. This periodic operation provides necessary user guidance while significantly reducing energy consumption compared to continuous light emission
Solution Approach 2:
The system dynamically changes the parameters of light emission (amount and blinking speed) based on the measured contact force. By adjusting these parameters only when needed to provide guidance, the system improves user operation while minimizing energy consumption during the measurement process
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
The apparatus provides accurate cuffless blood pressure measurement with improved user guidance, enhancing measurement precision and compactness, suitable for integration into mobile devices.
Implementation Method 1
a first light source configured to emit a first light, a second light source configured to emit a second light, and a photodetector configured to measure a pulse wave signal of an object based on the first light emitted by the first light source onto the object and returning from the object
Implementation Method 2
a photodetector configured to measure a pulse wave signal of an object based on the first light emitted by the first light source onto the object and returning from the object
Implementation Method 3
the second light may be a light of a green wavelength or a red wavelength
Data Source
AI summary
An apparatus for measuring blood pressure includes: a pulse wave measurer including a first light source configured to emit a first light, a second light source configured to emit a second light, and a photodetector configured to measure a pulse wave signal of an object based on the first light emitted by the first light source onto the object and returning from the object; a force measurer configured to measure a contact force between the object and the pulse wave measurer; and a processor configured to control emission of the second light from the second light source based on the measured contact force, and configured to estimate blood pressure of the object based on the measured pulse wave signal and the measured contact force.