Liquid Level Sensor and Detector
Patent, Filed 26 Feb 97, patented 24 Aug 99
DEPARTMENT OF THE NAVY WASHINGTON DC
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A light emitting photonic structure has a transparent substrate, such as sapphire, supporting a layer of group IV semiconductor material, such as silicon, having at least one porous region from which light is emitted as a response to a stimulus. An example of such a photonic structure is described in U.S. patent application Ser. No. 08118,900. The photonic structure can be used to assess the presence of various fluids. The photonic structure is disposed to be contacted by the fluid to be sensed should it be present. The light emitting region of the photonic structure is stimulated by an appropriate source, and the light emitted by the photonic source is detected by a detector. The light emitting region of the photonic structure will emit a certain luminescence in air and should the light emitting region be contacted by other fluid or fluids, this luminescence can be affected and the corresponding change in luminescence can be detected thus the presence of these fluids can be sensed. Because the photonic structure has a light emitting region is formed on a transparent substrate, the light emitting region can be both excited and interrogated through the transparent substrate and outside of the presence of the fluid to be sensed. Hence absorption of the excitation radiation used as well as the luminescence emitted by the fluid to be sensed is eliminated.
- Electrooptical and Optoelectronic Devices