Wireless Passive Resonators for High-Temperature Sensing
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Solution Overview
Problem
Current sensors for turbine engines, particularly in high-temperature sections, lack accuracy and reliability, with existing technologies like optical-based non-contact methods and wired ceramic sensors failing to provide detailed thermo-mechanical data and being limited by fabrication methods, cost, and temperature range.
Innovation Solution
Development of wireless passive resonators using polymer-derived ceramic (PDC) elements with a metal patch on a PDC layer, which function as both a sensor and antenna, allowing for temperature-dependent dielectric constant-based frequency changes for wireless sensing, enabling efficient energy transmission and operation beyond 1,000°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical-based non-contact technology is used for measuring physical and chemical parameters in turbine engines, then measurement capability is provided, but measurement accuracy is insufficient and the technology breaks down over time
Solution Approach 1:
The patent replaces optical-based measurement systems with a wireless resonant sensor system that uses electromagnetic resonance at microwave frequencies. The resonant sensor comprises a resonant cavity formed by a dielectric layer and metal patches, which resonates at a frequency that changes with temperature, pressure, or strain. This substitution provides both high measurement accuracy through precise frequency detection and long-term reliability since the passive resonant sensor has no moving parts and can withstand harsh high-temperature environments.
2Temperature
If wired ceramic sensors are used for high temperature sensing, then temperature measurement capability is provided, but the sensors cannot reach difficult locations and require complex wiring
Solution Approach 1:
The patent replaces wired ceramic sensors with a wireless resonant sensor system. The resonant sensor is excited by an external electromagnetic field from a reader device, eliminating the need for physical wiring connections. The sensor can be placed in difficult-to-reach locations within the turbine engine, such as on turbine blades or in combustion chambers, and the wireless communication allows data transmission without mechanical connectors that would fail in high-temperature environments.
Solution Approach 2:
The patent extracts the signal processing and power supply functions from the sensor itself, placing them in a separate reader device. The resonant sensor is passive and only needs to resonate in response to an external electromagnetic field. This separation allows the sensor to be miniaturized and placed in constrained locations while the reader, which contains the complex electronics, remains outside the harsh environment.
3Temperature
If SiC and Si3N4-based ceramic microsensors are used, then high temperature sensing is enabled, but fabrication methods are limited and cost is high
Solution Approach 1:
The patent uses a composite structure consisting of a polymer-derived ceramic (PDC) dielectric layer and metal patches (such as copper, aluminum, or nickel). The PDC layer is formed by pyrolysis of a preceramic polymer coating, which can be applied using low-cost techniques like dip-coating, spray-coating, or screen printing. This composite approach combines the high-temperature stability of ceramics with the ease of fabrication of polymer processing, eliminating the need for expensive and complex ceramic machining operations.
Solution Approach 2:
The patent changes the fabrication parameters from high-temperature ceramic processing to lower-temperature polymer processing followed by controlled pyrolysis. The preceramic polymer is coated at room or moderate temperature, then pyrolyzed in a controlled atmosphere to form the ceramic dielectric layer. This parameter change enables the use of standard polymer processing equipment and techniques, significantly reducing fabrication complexity and cost while maintaining high-temperature performance.
4Measurement precision
If PDC-based sensors are wired to signal processing systems, then resistance change sensing is enabled, but the wired arrangement cannot measure parameters in difficult to reach locations
Solution Approach 1:
The patent replaces the wired resistance-based sensing system with a wireless resonant sensing system. Instead of measuring resistance changes through electrical connections, the system measures changes in resonant frequency of an electromagnetic resonator. The resonant frequency shifts in response to temperature, pressure, or strain changes, and this frequency information is transmitted wirelessly to the reader device. This eliminates the need for wiring to difficult-to-reach locations while maintaining precise measurement capability.
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 solution provides robust, low-profile, high-temperature tolerant sensors that can accurately sense physical and environmental parameters wirelessly, overcoming limitations of existing sensors by enabling efficient energy transmission and operation in harsh environments, including within turbine engines.
Implementation Method 1
PDC materials are generally formed by the processing of materials referred to as 'preceramic polymers'... The polymer-to-ceramic conversion is achieved either thermally (pyrolysis) or non-thermally (for instance by irradiation with ions)... allowing production of SiO2, SiOC, SiC, Si3N4 and SiCN ceramics
Implementation Method 2
The polymer-to-ceramic conversion is achieved either thermally (pyrolysis) or non-thermally (for instance by irradiation with ions)
Implementation Method 3
for temperature sensing applications, the resonant frequency of the PDC element changes as a function of the temperature allowing the resonator to provide a signal indicative of its temperature
Implementation Method 4
a wireless RF reader transmits an RF interrogation signal... electromagnetic energy couples into the PDC element, which then reradiates (reflects) electromagnetic energy back to the interrogator antenna
Data Source
AI summary
A resonator for sensing a physical or an environmental parameter includes a support having a top surface that provides a ground plane, and a polymer-derived ceramic (PDC) element positioned on the top surface including a PDC layer, and a metal patch on the PDC layer. The metal patch is electrically isolated from all surrounding structure, and the resonator has a resonant frequency that changes as a function of the physical or environmental parameter. A system for wirelessly sensing a physical or environmental parameter includes at least one resonator and a wireless RF reader located remotely from the resonator for transmitting a wide-band RF interrogation signal that excites the resonator. The wireless RF reader detects a sensing signal retransmitted by the resonator and includes a processor for determining the physical or environmental parameter at the location of the resonator from the sensing signal.