초록 ▼

This disclosure relates to a method and apparatus for sensing the presence of gases, vapors, and liquids using surface acoustic waves. At the present time the commercially available devices for measuring the presence of fluids, although fast reacting and generally quite accurate, are very expensive

This disclosure relates to a method and apparatus for sensing the presence of gases, vapors, and liquids using surface acoustic waves. At the present time the commercially available devices for measuring the presence of fluids, although fast reacting and generally quite accurate, are very expensive and bulky. Further, these devices do not lend themselves to advanced integrated signal processing and digital techniques. This disclosure describes a precise, fluid sensing unit that is small, easily integrated, and relatively inexpensive to fabricate. The apparatus includes a medium on which surface acoustic waves can be propagated, transmitting and receiving transducers, and a sensing member located across the path of the surface acoustic waves. The sensing member has a physical characteristic that varies the velocity and/or the attenuation of the waves when in the presence of the specific fluid being detected. The presence of the fluid is sensed by the apparatus by measuring the variation in the surface acoustic waves resulting from this interaction.

대표청구항 ▼

Apparatus for sensing the presence of a specific fluid, comprising: (a) a substrate in which surface acoustic waves can be propagated, said substrate having a planar top surface and a planar bottom surface opposite thereto; (b) a transmitting transducer located on said top surface for propagating su

Apparatus for sensing the presence of a specific fluid, comprising: (a) a substrate in which surface acoustic waves can be propagated, said substrate having a planar top surface and a planar bottom surface opposite thereto; (b) a transmitting transducer located on said top surface for propagating surface acoustic waves in said substrate along a path; (c) a receiving transducer located on said top surface for receiving said surface acoustic waves propagated in said substrate along said path; and (d) a sensing member located on the bottom surface of the substrate in the path of the surface acoustic waves for interacting therewith and having a physical characteristic that varies the surface acoustic waves when in the presence of a specific fluid, said member interacts with the waves so that the presence of the fluid is sensed by the receiving transducer as a variation of the surface acoustic waves.