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High Temperature Optical Sapphire Pressure Sensors for Harsh Environments

The primary objective of this research is to develop a high-bandwidth pressure sensor to provide benchmark, time-resolved, dynamic pressure data in high-temperature combustion environments. Specifically, these sensors will be designed to be embedded within a system and provide remote interrogation which will enable pressure to be measured in situ and on line under extreme conditions. Ultimately, this sensing technology will lead to better understanding and increased efficiency of complex power generation systems. In order to achieve this objective, research in sapphire laser micromachining and thermocompression bonding via spark plasma sintering technology will be conducted to enable fabrication of a fiber optic lever pressure sensor that uses a sapphire optical fiber for transduction of the pressure-induced diaphragm deflection. The proposed project will result in instrumentation-grade, high-temperature sensors that enable flush mounted measurements without sensor cooling. Furthermore, the use of optical techniques enables “passive” device operation, with electronics located remotely from the sensor. After fabrication and packaging, the pressure sensor will be rigorously characterized in acoustic plane wave tubes under both ambient and high-temperature conditions to determine its performance as a quantitative measurement device.

A Flush-Mount Piezoelectric MEMS Microphone for Aeroacoustic Flight Testing Applications

In their effort to locate, understand and mitigate the impact of noise sources on an aircraft, aeroacousticiansare in need of a high performance, low cost microphone to combat the increasing noise restrictions on commercial aircraft. Existing commercial sensors, even with their relatively high cost, in some cases constrain the quality and type of measurement that may be achieved. One such constraint is that the physical size and characteristics of the sensors limit the optimal locations in which the sensors may be placed. Previous generations of MEMS aeroacoustic microphones have failed to address the need for a sensor that can be packaged and installed with a smooth front surface to be used for boundary layer measurements in a fuselage array at cruise conditions. Additionally, these microphones must meet demanding requirements, including the sensing of high sound pressure levels (>160 dB) with low distortion (<3%) and high sensitivity stability (with respect to moisture and freezing) over temperatures from -60°F to 150°F. This work addresses the limitations of existing MEMS piezoelectric microphones used in aeroacoustic applications by incorporating through-silicon vias(TSVs) into the fabrication to eliminate the use of wirebondsthat affect the flow field and create an overall flush-mount microphone package.

A MEMS-based Fast-response Five-hole Probe with Optical Pressure Transducers

The goal of this research is to develop a MEMS-based Five-hole Probe(5HP) that is able to measure the localized velocity vector (both the velocity magnitude and direction) and the static and dynamic pressure, in steady and/or unsteady flow fields. Five optical pressure sensors located on the hemisphere tip of the 5HP provide all information that is needed to resolve the flow. This 5HP is expected to be able to provide high spatial resolution, high frequency response and is compatible with elevated temperature environments. A primary focus of this research is on the microfabrication and micromachining of a die that incorporates five optical transducers and its successive packaging process. The completed sensors will be tested in flow cells and wind tunnels at UF for the final calibration.