Surface acoustic wave sensor

• US 6,314,791 B1
• Filed: 02/23/2000
• Issued: 11/13/2001
• Est. Priority Date: 10/20/1997
• Status: Expired due to Fees

• Current Assignee: Forschungszentrum Karlsruhe Gmbh
• Original Assignee: Forschungszentrum Karlsruhe Gmbh
• Inventors: Voigt, Achim, Rapp, Michael
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): MILLER, ROSE MARY
• Application Number:
  US09/511,686
• Time in Patent Office: 629 Days
• Field of Search: 73/240.1, 73/240.5, 73/240.6, 73/310.5, 73/310.6, 73/32.A, 73/544.1, 73/617.9, 310/313.R, 310/313.B, 310/313.D
• US Class Current: 73/24.06
• CPC Class Codes: G01N 2291/012 Phase angle
• CPC Class Codes: G01N 2291/0256 Adsorption, desorption, surface mass change, e.g. on biosensors
• CPC Class Codes: G01N 2291/0423 Surface waves, e.g. Rayleigh waves, Love waves
• CPC Class Codes: G01N 2291/106 one or more transducer arrays
• CPC Class Codes: G01N 29/022 Fluid sensors based on microsensors, e.g. quartz crystal-microbalance [QCM], surface acoustic wave [SAW] devices, tuning forks, cantilevers, flexural plate wave [FPW] devices microdevices per se B81B

Abstract

In a sensor comprising a housing, through which a medium to be examined is conducted, the housing includes at least two passive building components capable of oscillating and oscillator circuits of which each includes an amplifier component and a variable phase shifting component providing for a phase shift range sufficiently large to switch the oscillating components off while the amplifier component remains operating.

Claims

1. A sensor comprising a housing, at least two passive building components capable of oscillating together with oscillator circuits disposed in said housing, means for supplying a medium to be examined to said housing and means for removing said medium from said housing, said oscillator circuits each including an amplifier component and a variable phase-shifting component providing for a phase shift range sufficiently large to switch the oscillation of the oscillating components off while said amplifier component remains operative.

2. A sensor according to claim 1, wherein said passive components capable of oscillating are surface acoustic wave building components (SAW).

3. A sensor according to claim 1, wherein said passive components capable of oscillating are oscillation quartzes.

4. A sensor according to claim 1, wherein said passive components capable of oscillating are LC members.

5. A sensor according to claim 1, wherein said variable phase shifting component is an LC low-pass π

member with capacitance diodes.

6. A sensor according to claim 5, including a circuit for the selective control of the capacitance diodes.

7. A sensor according to claim 1, including a reference oscillator for the downward mixing of the signals.