This paper studies the effect of thin film thickness on visibility readout from an interferometric pressure sensor. Interference fringes between a silicon nitride diaphragm and a glass substrate are formed as a function of pressure and can be captured using a camera. Image processing software was used to analyze and correlate the fringe pattern to pressure. Visibility of the interference fringes is optimized by depositing a thin silicon nitride layer on the glass substrate of the sensor using plasma enhanced chemical vapor deposition (PECVD). Optimal visibility was obtained with a coating thickness of 79 nm. Visibility was increased by 150% in comparison to no coating.
Volume Subject Area:Biomedical Equipment, Medical Robotics/Devices
Topics:Optimization, Pressure measurement, Pressure sensors, Coating processes, Coatings, Glass, Plasma-enhanced chemical vapor deposition, Pressure, Silicon nitride ceramics, Computer software, Diaphragms (Mechanical devices), Diaphragms (Structural), Diffraction patterns, Image processing, Sensors, Thin films
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