Pulse Wave Sensor Unit Closed Space Design
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Solution Overview
Problem
The tonometry method for continuously measuring pulse waves is burdensome for subjects due to the need for prolonged pressure maintenance on arteries, making long-term measurement challenging.
Innovation Solution
A pulse wave sensor unit with a pressure sensor featuring a diaphragm part and an annular support, along with a wiring circuit board and connecting means, forms a closed space to measure pulse waves without directly pressing blood vessels, utilizing a piezo-resistor and seal member to detect skin surface changes from blood pressure variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the artery is evenly pressed to measure pulse wave continuously, then the pulse wave can be measured continuously, but the measurement for a long time becomes a burden to the subject
Solution Approach 1:
The patent replaces the traditional mechanical tonometry method (direct pressure application to artery) with a non-contact optical measurement system. The light source emits light that passes through the measurement portion, and the light receiving element detects changes in light intensity caused by blood volume changes, thereby measuring pulse waves without mechanical pressure on the subject.
Solution Approach 2:
The patent introduces light as an intermediary medium between the measurement portion and the detection system. Instead of directly pressing the artery, the system uses light transmission through the skin and underlying blood vessels to detect pulse wave changes, eliminating direct mechanical contact while maintaining measurement capability.
2Device complexity
If a pressure sensor directly contacts the measurement portion, then the sensor structure is simple, but the measurement accuracy deteriorates due to pressing the blood vessel
Solution Approach 1:
The patent replaces the mechanical contact-based pressure sensor with an optical measurement system. The light source and light receiving element are positioned to transmit and detect light through the measurement portion without mechanical contact, thereby maintaining simple device structure while improving measurement accuracy by eliminating vessel compression artifacts.
3Ease of manufacture
If the sensor unit is made disposable to reduce costs, then the cost is reduced, but the device complexity increases due to additional components needed for single-use configuration
Solution Approach 1:
The patent integrates the light source, light receiving element, and necessary circuitry into a single integrated sensor unit that can be disposed of after one use. This merging of components simplifies the overall system architecture for disposable use, eliminating the need for complex reusable components while maintaining measurement functionality through integrated optics and electronics.
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 continuous long-term pulse wave measurement without pressing blood vessels, improving detection accuracy and reducing subject burden, while also miniaturizing the sensor unit and reducing costs for disposable use.
Implementation Method 1
the pressure sensor may include a piezo-resistor which is provided in the diaphragm part
Data Source
AI summary
A pulse wave sensor unit includes a pressure sensor, and an adhesive tape to attach the pressure sensor to a measurement portion to be measured. The pressure sensor includes a diaphragm part, and an annular support part which supports the diaphragm part and has an aperture for allowing the diaphragm part to face the measurement portion, and a closed space is able to be formed between the diaphragm part and the measurement portion by attaching the pressure sensor to the measurement portion using the adhesive tape.