Abstract
This paper presents an all-SiC fiber-optic Fabry-Perot (FP) pressure sensor based on the hydrophilic direct bonding technology for the applications in the harsh environment. The operating principle, fabrication, interface characteristics, and pressure response test of the proposed all-SiC pressure sensor are discussed. The FP cavity is formed by hermetically direct bonding of two-layer SiC wafers, including a thinned SiC diaphragm and a SiC wafer with an etched cavity. White light interference is used for the detection and demodulation of the sensor pressure signals. Experimental results demonstrate the sensing capabilities for the pressure range up to 800 kPa. The all-SiC structure without any intermediate layer can avoid the sensor failure caused by the thermal expansion coefficient mismatch and therefore has a great potential for pressure measurement in high temperature environments.
Highlights
High temperature pressure sensors that can precisely monitor static and dynamic pressures are of great significance for various industrial and aerospace systems under extremely harsh environments, such as turbine engines and high-speed aircraft [1]
We propose an all-Silicon carbide (SiC) extrinsic Fabry-Perot interferometer (EFPI) pressure sensor based on the hydrophilic direct bonding technology for high temperature applications
In order to observe the internal structure of the SiC sample, Scanning electron microscope (SEM) observation is performed after etching and direct bonding
Summary
High temperature pressure sensors that can precisely monitor static and dynamic pressures are of great significance for various industrial and aerospace systems under extremely harsh environments, such as turbine engines and high-speed aircraft [1]. SiC-based high-temperature pressure sensors based on piezoresistive and capacitive detection mechanisms have demonstrated sensing capabilities in the temperature range of 350 °C – 600 °C[9,10,11,12]. Scanning electron microscope (SEM) characterization and the tensile test are performed for evaluating the direct bonding quality Since both the diaphragm and the substrate are composed of single crystal SiC and the bonding is performed without using any intermediate material, sensor failure attributed to thermal expansion mismatch and internal stress can be effectively avoided. The sensing capability of the as-fabricated sensor has been demonstrated and tested over a pressure range of 0 kPa to 800 kPa
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