Integrated PPG and Contact-Pressure Sensor for Blood Pressure Estimation
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Solution Overview
Problem
Existing methods for measuring blood pressure using a combination of pressure and volume sensors face challenges in compact design due to the separation of measurement positions, making it difficult to synchronize bio-signals and pressure signals effectively.
Innovation Solution
A sensor apparatus that integrates a transparent elastic body with polarizing films and detectors to measure photoplethysmography (PPG) and contact pressure signals simultaneously, using a single sensor to estimate blood pressure by analyzing oscillometric waveform envelopes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate pressure sensor and volume sensor are used to measure blood pressure, then measurement functions are complete, but device size increases and measurement positions cannot be synchronized
Solution Approach 1:
The patent combines a pressure sensor and a volume sensor (PPG sensor) into a single integrated sensor unit. The pressure sensor measures contact pressure on the skin surface while the PPG sensor measures blood volume changes at the same location. By merging these two separate sensing functions into one device, the patent achieves synchronized measurement at identical positions without increasing overall device size, thereby resolving the contradiction between measurement completeness and compactness.
Solution Approach 2:
The integrated sensor unit performs multiple functions simultaneously: it measures both pressure (through the pressure sensor) and blood volume changes (through the PPG sensor) at the same measurement position. This multi-functional design allows a single sensor to replace what would traditionally require two separate sensors, achieving both pressure and volume measurement capabilities while maintaining a compact form factor.
2Measurement precision
If separate pressure sensor and volume sensor are used, then measurement functions are complete, but measurement positions cannot be synchronized
Solution Approach 1:
The patent merges the pressure sensor and PPG sensor into a single integrated unit where both sensors are positioned to measure at the same location on the skin. This merging ensures that pressure and volume signals are synchronized by definition, as they originate from the same measurement position. The integrated structure eliminates the complexity of coordinating separate sensors while achieving precise signal synchronization.
3Volume of moving object
If integrated sensor is used to measure both pressure and volume, then device size is reduced, but manufacturing complexity increases
Solution Approach 1:
The integrated sensor is manufactured as a modular assembly with distinct pressure sensing and PPG sensing components. Each sensor type maintains its own functional structure while being positioned within the same housing or substrate. This segmented approach allows each sensor type to be manufactured using its optimized process, then assembled together, reducing the overall manufacturing complexity compared to creating a fully integrated single-component sensor.
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 compact and accurate estimation of blood pressure by combining PPG and contact pressure signals, overcoming the limitations of separate sensors and allowing for precise blood pressure estimation in a wearable device.
Implementation Method 1
a first detector provided under the transparent elastic body and configured to detect a light, passing through the first polarizing film after being emitted by the light source and scattered or reflected from the object
Implementation Method 2
a first detector provided under the transparent elastic body and configured to detect a light, passing through the first polarizing film after being emitted by the light source and scattered or reflected from the object
Implementation Method 3
a first polarizing film provided on a surface of the transparent elastic body and configured to come into contact with the object
Implementation Method 4
a second detector provided under the transparent elastic body and configured to detect a light, not passing through the first polarizing film
Data Source
AI summary
An apparatus for estimating blood pressure includes: a sensor, and a processor configured to estimate blood pressure based on a PPG signal and a contact pressure signal measured by the sensor. The sensor includes: a transparent elastic body; a first polarizing film provided on a surface of the transparent elastic body and configured to come into contact with the object; a light source provided under the transparent elastic body and configured to emit light toward the object; a first detector and a second detector provided under the transparent elastic body and configured to detect light, passing through the first polarizing film after being emitted by the light source and scattered or reflected from the object, to measure the PPG signal; and a second detector provided under the transparent elastic body and configured to detect light, not passing through the first polarizing film, to measure the contact pressure signal.