Tilted Quartz Acoustic Wave Sensor for Differential Temperature Sensing
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Solution Overview
Problem
Existing acoustic wave sensors face challenges in achieving reliable measurement results due to demanding production tolerances, reproducibility issues, and environmental influences, which affect the signal-to-noise ratio and accuracy of differential measurements.
Innovation Solution
A two-port acoustic wave sensor device with a quartz material layer having specific crystal cuts and tilted interdigitated transducers and reflection structures, allowing for differential sensitivity and improved resonance frequencies, is designed to enhance measurement reliability and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional acoustic wave sensors are used with standard crystal cuts and parallel transducer arrangements, then the device structure is simple and manufacturing is easier, but the measurement precision and signal-to-noise ratio are insufficient due to environmental influences and production tolerances
Solution Approach 1:
The patent applies asymmetry by tilting the interdigitated transducers and reflection structures relative to the crystallographic axes of the quartz substrate. Specifically, the transducers are oriented at angles (e.g., 30° or 45°) to the X-axis rather than parallel to it, creating an asymmetric configuration that generates differential sensitivity to environmental parameters while maintaining structural feasibility
Solution Approach 2:
The patent changes the crystal cut parameters of the quartz substrate from conventional orientations (like YX-cut at 0°) to specific angled cuts (e.g., YX-cut at 30° or 45° relative to the X-axis). This parameter change in crystal orientation enables the acoustic waves to propagate with different polarizations and velocities, thereby achieving high differential sensitivity to temperature and other environmental factors
2Reliability
If conventional acoustic wave sensors are used with standard configurations, then the manufacturing process is simpler, but the reliability and robustness against environmental influences are reduced
Solution Approach 1:
The asymmetric tilting of transducers and reflection structures at specific angles to the crystallographic axes creates differential sensitivity to environmental parameters. This asymmetric configuration ensures that the sensor responds differently to temperature, pressure, and other factors, thereby improving reliability through enhanced environmental robustness while maintaining a manufacturable structure
Solution Approach 2:
The patent applies local quality by creating specific regions with different orientations and properties. The quartz substrate is cut at specific angles, and transducers are positioned at specific orientations relative to the crystallographic axes, creating locally optimized regions that collectively provide robust environmental performance
3Measurement precision
If conventional acoustic wave sensors are used with parallel transducer arrangements, then the device structure is simpler, but the signal-to-noise ratio and differential measurement sensitivity are insufficient
Solution Approach 1:
The patent tilts the interdigitated transducers and reflection structures at specific angles (e.g., 30° or 45°) relative to the X-axis of the quartz substrate, creating an asymmetric configuration. This asymmetry generates differential sensitivity to environmental parameters, significantly improving the signal-to-noise ratio for differential measurements while maintaining a relatively simple overall device structure
Solution Approach 2:
The patent changes the orientation parameters of the transducers and reflection structures from conventional parallel arrangements to specific angled orientations relative to the crystallographic axes. This parameter change in transducer orientation enables the generation of acoustic waves with optimized polarization and propagation characteristics, thereby achieving high signal-to-noise ratio
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 sensor provides a high signal-to-noise ratio, robustness against environmental influences, and accurate differential measurements with sensitivity to temperature changes, achieving a differential measurement sensitivity of more than 1 ppm/K and second-order TCF sensitivity less than 10 ppb/K^2.
Implementation Method 1
Acoustic wave sensors utilize the piezoelectric effect to transduce an electrical signal into a mechanical/acoustic wave
Implementation Method 2
an interdigitated transducer (IDT), converts the electrical energy of the electrical signal into acoustic wave energy
Implementation Method 3
the other (output) IDT is replaced by a reflector that reflects the generated acoustic wave back to the (input) IDT
Data Source
AI summary
An acoustic wave sensor device comprises a quartz material layer surface; arranged along a first axis, a first interdigitated transducer disposed over the planar surface of the quartz material layer, a first reflection structure disposed over the planar surface of the quartz material layer, and a second reflection structure disposed over the planar surface of the quartz material layer; and arranged along a second axis, a second interdigitated transducer disposed over the planar surface of the quartz material layer, a third reflection structure disposed over the planar surface of the quartz material layer, and a fourth reflection structure disposed over the planar surface of the quartz material layer; and wherein the first axis and the second axis are inclined to each other by a finite angle.