Reflective-Tag SAW Sensor Structure for Wireless High-Temperature Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing surface acoustic wave (SAW) devices are limited by a high temperature boundary, often failing to operate reliably above 300°C, and require a power source or wired connections, which restricts their application in high-temperature environments.
Innovation Solution
A sensor device comprising a piezoelectric transducer attached to a non-piezoelectric base member, such as sapphire, with an excitation electrode that uses externally supplied voltage to generate surface acoustic waves, which are reflected and used to measure physical parameters like temperature without the need for a direct power source or wired connections, employing a configuration that allows for both input and output transducer functionality in a single unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional SAW devices are used for temperature measurement, then they can operate at moderate temperatures, but they fail to operate reliably above 300°C due to high temperature boundary limitations
Solution Approach 1:
The patent changes the material parameters of the base member from conventional piezoelectric materials to sapphire (Al2O3), which has superior high-temperature stability. This material substitution enables the device to operate reliably at temperatures up to 600°C or higher, fundamentally resolving the temperature boundary limitation of conventional SAW devices.
Solution Approach 2:
The patent employs a composite structure combining a sapphire base member with piezoelectric transducer materials. The sapphire substrate provides high-temperature structural stability while the piezoelectric layer enables acoustic wave generation and detection, creating a composite system that leverages the advantages of both materials for high-temperature operation.
2Ease of operation
If piezoelectric transducers are wired to power sources for operation, then they can generate and detect acoustic waves, but they require cable connections and power sources that restrict application in high-temperature environments
Solution Approach 1:
The patent implements a self-service mechanism where the piezoelectric transducer serves dual functions: it generates acoustic waves when receiving electrical signals and detects reflected waves to produce measurement outputs. This bidirectional functionality eliminates the need for separate power sources and wired connections, enabling wireless operation while reducing device complexity.
Solution Approach 2:
The piezoelectric transducer is designed to perform multiple functions: it acts as both an actuator (converting electrical energy to mechanical acoustic waves) and a sensor (converting mechanical acoustic waves back to electrical signals). This multi-functionality allows the device to operate wirelessly without requiring separate power supply and signal transmission components.
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 reliable temperature measurements and other physical parameter detection in high-temperature environments up to 600°C or more, with improved signal-to-noise ratio and robustness, facilitating wireless operation and reducing the need for power sources or cables.
Implementation Method 1
The primary function of an interdigital transducer is to convert electric signals to surface acoustic waves, SAW, by generating periodically distributed mechanical forces via piezoelectric effect in an input transducer
Implementation Method 2
The vibration of the piezoelectric member is transferred to the base member and propagates as a surface acoustic wave on the surface of the base member. The surface acoustic wave is reflected at the at least one acoustic wave reflecting tag
Implementation Method 3
The reflected surface acoustic wave is transferred to the piezoelectric member and mechanically excites the piezoelectric member. Due to the excitation of the piezoelectric member an oscillating voltage is generated at the excitation electrode
Data Source
AI summary
A sensor device (1) comprises a piezoelectric transducer (3) and a base member (2). The piezoelectric transducer includes a piezoelectric member with at least one excitation electrode (37, 38) connected to a first face thereof and having a thickness (h) between the first face and a second face. The piezoelectric transducer (3) is attached to a supporting face of the base member (2) with the second face of the piezoelectric transducer positioned adjacent the supporting face of the base member. The base member includes at least one acoustic wave reflecting tag (21) distant from the piezoelectric member.