Tuning Fork Fluid Sensor Electrode Layout for High-Viscosity Sensing
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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, while effectively measuring fluid properties such as viscosity, density, and electrical conductivity.
Innovation Solution
A fluid sensor utilizing a tuning fork mechanical resonator made from lithium tantalate piezoelectric material, with strategically arranged electrodes on the tines and base, providing improved mechanical robustness, chemical stability, and reduced temperature sensitivity, allowing for accurate measurement of fluid properties even in high viscosity conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional piezoelectric materials are used in the tuning fork resonator, then the sensor can operate in fluid environments, but the mechanical robustness and chemical stability are insufficient for extended temperature ranges and harsh environments
Solution Approach 1:
The patent changes the material parameter from conventional piezoelectric materials to lithium tantalate, which has superior mechanical properties and chemical stability. This material substitution enables the sensor to withstand extended temperature ranges and harsh environments, directly resolving the contradiction between reliability and environmental resistance
Solution Approach 2:
The patent employs lithium tantalate as a piezoelectric material that combines both mechanical robustness and chemical stability in a single material system. This composite approach provides integrated protection against both mechanical stress and chemical degradation in harsh environments
2Measurement precision
If electrodes are provided only on the tines, then the structure is simple, but the electric field generation is limited and sensitivity is reduced
Solution Approach 1:
The patent segments the electrode arrangement into two distinct locations: electrodes on the tines and additional electrodes on the base. This segmentation allows each electrode group to perform specific functions - the tine electrodes generate the primary oscillation field while the base electrodes enhance the overall electric field distribution, thereby improving sensitivity without creating a monolithic complex structure
Solution Approach 2:
The patent extends the electrode arrangement from a one-dimensional configuration (only on tines) to a two-dimensional configuration (tines and base). This dimensional expansion creates a more comprehensive electric field coverage in the fluid, enhancing the sensor's ability to detect fluid properties while maintaining structural organization
3Measurement precision
If the electrode length is short, then the device is compact, but the resonance signal detection is insufficient in high viscosity conditions
Solution Approach 1:
The patent implements electrodes with optimized length (3-10 mm) that are sufficiently long to generate strong electric fields before the oscillation signal diminishes in high viscosity fluids. This preliminary action ensures that the resonance signal is adequately detected during the critical oscillation phase, preventing signal loss in challenging fluid conditions
4Reliability
If the crystal cut angle is not optimized, then the manufacturing is simpler, but the temperature sensitivity of the sensor response increases
Solution Approach 1:
The patent optimizes the crystal cut angle parameter to a specific range (110-140 degrees on rotated Y-cut) that minimizes temperature sensitivity. This precise parameter control compensates for the increased manufacturing precision requirement by selecting an angle range that provides inherent temperature stability, reducing the overall impact of manufacturing variations
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 lithium tantalate-based fluid sensor achieves increased reliability and extended lifespan by enhancing mechanical resistance and sensitivity, enabling reliable measurements across a broad temperature and viscosity range, including high viscosity fluids up to 20,000 cP.
Implementation Method 1
The base and the at least one tine are formed in a piezoelectric material... Upon application of a voltage, the two tines oscillate and generate a response indicative of the physicochemical and electrical properties of the fluid
Data Source
Figure 1a~1b
Figure 2~4
Figure 5~6
AI summary
The present invention relates to a fluid sensor for sensing a plurality of properties of a fluid to be sensed, comprising a tuning fork mechanical resonator (3). The tuning fork mechanical resonator (3) comprises a base (11) and at least one tine (15A, 15B) projecting from the base (11), the base (11) and the at least one tine (15A, 15B) being formed in a piezoelectric material, and the at least one tine comprises at least two electrodes (17A-B; 19A-B) configured to be exposed to the fluid. The piezoelectric material comprises lithium tantalate.