Lithium Tantalate Tuning Fork Fluid Sensor for Harsh Temperatures
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Solution Overview
Problem
Existing fluid sensors face challenges in enhancing their lifetime and reliability, particularly in extended temperature ranges and harsh environments, as they are not adequately robust to withstand mechanical and chemical stress.
Innovation Solution
A fluid sensor is designed with a tuning fork mechanical resonator made from lithium tantalate piezoelectric material, featuring electrodes exposed to the fluid, which allows for improved robustness and reduced influence of the piezoelectric material on measurements, enabling the determination of fluid properties like viscosity, density, and electrical resistivity, while being less temperature-dependent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional resonator materials are used, then the sensor can operate in standard conditions, but the lifetime and reliability deteriorate in extended temperature ranges and harsh environments
Solution Approach 1:
The patent changes the material parameter from traditional quartz to lithium tantalate piezoelectric material, which has superior thermal stability and chemical resistance. This material substitution enables the sensor to maintain reliable operation in extended temperature ranges and harsh environments while preserving the piezoelectric effect necessary for sensing functionality.
Solution Approach 2:
The patent employs lithium tantalate as a piezoelectric material that combines multiple desirable properties: piezoelectricity for sensing, chemical inertness for resistance to harsh environments, and thermal stability for extended temperature operation. This composite material approach resolves the contradiction by integrating multiple functional requirements into a single material system.
2Measurement precision
If the piezoelectric material is exposed to fluid, then fluid properties can be sensed, but the material influence on measurements increases
Solution Approach 1:
The patent applies local quality by exposing only specific regions (the tines) of the lithium tantalate resonator to the fluid, while other parts remain protected. This localized exposure minimizes the overall material-fluid interaction and reduces spurious signals while maintaining the necessary sensing capability at the exposed interface.
Solution Approach 2:
The patent uses the mechanical vibration of the resonator as an intermediary that copies the fluid's physical properties into measurable electrical signals through the piezoelectric effect. This indirect measurement approach reduces direct material-fluid interaction effects while preserving the essential sensing information.
3Duration of action of stationary object
If the resonator is made robust for harsh environments, then lifetime increases, but temperature dependence of measurements increases
Solution Approach 1:
The patent selects lithium tantalate with specific piezoelectric and thermal properties that provide both robustness for harsh environments and reduced temperature dependence. The material's inherent stability parameters enable long sensor lifetime while maintaining measurement precision across varying temperatures.
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 use of lithium tantalate enhances the sensor's reliability and extends its lifetime, allowing it to function effectively in broad temperature and viscosity conditions, including high viscosity fluids, by maintaining resonance signal quality and resisting shear forces.
Implementation Method 1
The base and the tine are formed from a piezoelectric material including lithium tantalate. Such a resonator deforms upon application of a voltage and reciprocally electrically polarizes under the action of mechanical stress.
Implementation Method 2
Upon application of a voltage, the two tines oscillate and generate a response indicative of the physicochemical and electrical properties of the fluid wherein the fluid sensor is immersed.
Implementation Method 3
tuning fork mechanical resonator including a base and a tine projecting from the base along a longitudinal direction of the tine
Data Source
AI summary
A fluid sensor includes a tuning fork mechanical resonator including a base and a tine projecting from the base along a longitudinal direction of the tine, and a pair of electrodes disposed on the tine. The base and the tine are formed from a piezoelectric material including lithium tantalate. The electrodes are exposed to a fluid.