Wireless MEMS Piezoelectric Resonator Sensor
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Solution Overview
Problem
Existing resonant sensors require signal conditioning and digital conversion, which complicates the measurement of physical parameters like acceleration and pressure, and existing wireless sensors lack efficient methods for remote interrogation.
Innovation Solution
The development of wireless piezoelectric MEMS sensors that integrate a piezoelectric resonator and a variable capacitor on the same substrate, allowing for frequency shifts to be used for sensing physical parameters, enabling remote interrogation through a resonant frequency change without the need for on-chip electronics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If resonant sensors are used to sense physical parameters, then measurement precision is improved, but device complexity increases due to required signal conditioning and digital conversion circuits
Solution Approach 1:
The patent extracts and removes the complex signal conditioning and digital conversion circuitry from the sensor system, retaining only the essential resonant sensing element. The solution leverages the inherent frequency-shift-to-capacitance conversion capability of the resonant sensor to directly interface with measurement systems, eliminating the need for intermediate signal processing stages while preserving measurement precision.
Solution Approach 2:
The patent replaces the traditional electronic signal conditioning approach with a direct frequency-based measurement method. By measuring the frequency shift of the resonant element, the system substitutes complex electronic signal processing with a simpler frequency detection mechanism, reducing device complexity while maintaining measurement capability.
2Device complexity
If wireless sensors are designed without on-chip electronics, then device complexity and power consumption are reduced, but ease of operation and remote interrogation capability deteriorate
Solution Approach 1:
The patent introduces an intermediary coupling mechanism between the resonant sensor and the external measurement system. This intermediary enables wireless remote interrogation of the sensor by converting the resonant frequency shifts into detectable signals that can be transmitted and measured externally, eliminating the need for on-chip electronics while preserving remote operation capability.
3Adaptability or versatility
If variable capacitor is electrically coupled to resonator to sense physical parameters, then adaptability is improved, but measurement precision deteriorates due to frequency shift affecting resonator performance
Solution Approach 1:
The patent performs preliminary characterization and compensation of the frequency shift effects caused by the variable capacitor coupling. By pre-calculating and accounting for these frequency shifts in the measurement algorithm, the system maintains measurement precision while preserving the adaptability to sense multiple physical parameters through the same resonant structure.
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
These sensors provide high-resolution, wireless, and passive measurement of physical parameters like acceleration and pressure, achieving accurate and efficient sensing with minimal power consumption and no need for on-chip electronics, suitable for applications such as wireless body movement monitoring and vibration sensing.
Implementation Method 1
a piezoelectric layer thereon; a MEMS piezoelectric resonator including a reference electrode on a first side of the piezoelectric layer
Implementation Method 2
A variable capacitor on the substrate is positioned lateral to the MEMS piezoelectric resonator having a first plate and a second plate that are connected to port 1. Responsive to a physical parameter a capacitance of the variable capacitor changes which changes a frequency of the MEMS piezoelectric resonator
Implementation Method 3
The MEMS piezoelectric resonator has a natural resonant frequency. Responsive to a physical parameter a capacitance of the variable capacitor changes which changes a frequency of the MEMS piezoelectric resonator relative to the natural resonant frequency to generate a frequency shift.
Data Source
AI summary
A microelectromechanical system (MEMS) sensor includes a substrate having a piezoelectric layer thereon; a MEMS piezoelectric resonator including a reference electrode on a first side of the piezoelectric layer, a first port (port 1) including a capacitor coupling electrode on a side of the piezoelectric layer opposite the first side, and a second port (port 2) for excitation signal coupling including another electrode on the side opposite the first side. The MEMS piezoelectric resonator has a natural resonant frequency. A variable capacitor on the substrate is positioned lateral to the MEMS piezoelectric resonator having a first and a second plate are connected to port 1. An antenna or an oscillator circuit is connected to port 2. Responsive to a physical parameter a capacitance of the variable capacitor changes which changes a frequency of the MEMS piezoelectric resonator relative to the natural resonant frequency to generate a frequency shift.