Piezoelectric Vibration Sensor for Wearable Pulse Waveform Analysis
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Solution Overview
Problem
Existing pulse oximeters consume high power due to continuous LED light output, making them unsuitable for wearable devices, and lack sufficient resolution for continuous pulse acceleration waveform measurement, which is crucial for monitoring arterial sclerosis and stress levels.
Innovation Solution
A vibration waveform sensor using a piezoelectric element on a circuit board that measures vibrations through a conductive vibration-conveying body, reducing power consumption and enabling continuous measurement of pulse waveforms with high resolution, suitable for wearable applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If continuous LED light output is used for pulse detection, then pulse waveform measurement is enabled, but power consumption increases to mW level
Solution Approach 1:
The patent replaces the optical detection system (LED light source) with a piezoelectric-based mechanical vibration detection system. The piezoelectric element converts mechanical vibrations of the blood vessel wall directly into electrical signals, eliminating the need for continuous LED light output and thereby reducing power consumption to microW level while maintaining pulse waveform measurement capability
Solution Approach 2:
The patent changes the detection parameter from optical absorption (light-based) to mechanical vibration (piezoelectric-based). This parameter change allows the system to detect pulse waves through mechanical vibrations rather than continuous light illumination, resolving the contradiction between measurement capability and power consumption
2Measurement precision
If traditional pulse detection processing is used, then pulse waveforms can be obtained, but measurement time increases to 10-5 msec
Solution Approach 1:
The piezoelectric element performs preliminary conversion of mechanical vibrations to electrical signals in real-time at the sensing location, eliminating the need for subsequent complex signal processing steps. This preliminary action at the source enables immediate waveform acquisition without the 10-5 msec delay associated with traditional post-processing methods
3Measurement precision
If LED light absorption method is used, then blood oxygen levels and volume pulse waveforms can be obtained, but measurement resolution is insufficient
Solution Approach 1:
The patent substitutes the optical absorption method with direct mechanical vibration detection using piezoelectric elements. This replacement provides superior measurement resolution by directly capturing the mechanical vibrations of the blood vessel wall without the limitations of optical methods, enabling detailed analysis of pulse waveform characteristics
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, low-power measurement and analysis of vibration waveforms, facilitating real-time monitoring of vascular conditions and stress levels without the need for complex differential calculations, suitable for wearable devices.
Implementation Method 1
a piezoelectric element provided on the circuit board, that continuously measures the vibrations of the circuit board to obtain vibration waveforms
Data Source
AI summary
In an embodiment, a sensor module 10 includes a piezoelectric element 30 placed on the principal face of a board 20, which piezoelectric element is surrounded by a vibration ring 40 and installed in an appropriate position on a person's arm, neck, etc., using a medical fixing tape, etc., with the vibration ring 40 contacting the person's skin. When a pulse wave is transmitted to the vibration ring 40 from the skin, the board 20 also vibrates and this vibration is transmitted to the piezoelectric element 30. Then, the piezoelectric element 30 is displaced and the pulse wave vibration is converted to an electrical signal. The resulting electrical signal is amplified by an amplifier on the board 20 and input to the vibration analysis device 100, where prescribed calculations are run to perform waveform analysis. The vascular state, etc., can be known from pulse waveforms.