SENSOR AND A SENSOR SYSTEM

• US 20130336095A1
• Filed: 12/07/2011
• Published: 12/19/2013
• Est. Priority Date: 12/20/2010
• Status: Active Grant

• Current Assignee: Teknologian tutkimuskeskus VTT Oy
• Original Assignee: Teknologian tutkimuskeskus VTT Oy
• Inventors: Seppa, Heikki, Sillanpaa, Teuvo, Viikari, Ville
• Granted Patent: US 10,673,537 B2
• Time in Patent Office: Days
• US Class Current: 367/137
• CPC Class Codes: B06B 1/0292 Electrostatic transducers, e.g. electret-type
• CPC Class Codes: G01D 21/00 Measuring or testing not otherwise provided for
• CPC Class Codes: G01L 11/06 Ultrasonic means
• CPC Class Codes: G01L 19/086 for remote indication
• CPC Class Codes: G01L 9/0016 of a diaphragm
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: H04B 11/00 Transmission systems employing sonic, ultrasonic or infrasonic waves

Abstract

The invention relates to a sensor and a system for measuring pressure, variation in sound pressure, a magnetic field, acceleration, vibration, or the composition of a gas. The sensor comprises an ultrasound transmitter, a cavity, and a passive sensor element. In accordance with the invention the sensor includes antenna means for receiving radio frequency signals (f1, f2), and connecting means connecting the antenna to the ultrasound transmitter for using the radio frequency signals for providing energy for driving the ultrasound transmitter.

Claims

1. A wireless sensor which comprises;

an electrostatically actuated ultrasound transmitter loaded with a fluid-filled cavity, and

an antenna or a coupling element matched to the ultrasound transmitter.

3. A sensor in accordance with claim 1, wherein the antenna is a loop antenna.

4. A sensor in accordance with claim 1, wherein the antenna is a dipole antenna.

2. A wireless sensor in for measuring pressure, variation in sound pressure, a magnetic field, acceleration, vibration, strain, stress, torque, temperature, electric field, electromagnetic radiation, viscosity of fluid, specific heat capacity of fluid, fluid flow, or the composition of a gas, comprising;

an ultrasound transmitter having a light-construction diaphragm oscillator which is well connected to the surrounding medium,

a cavity arranged in connection with the ultrasound transmitter which affects the mechanical impedance of the ultrasound transmitter,

a sensor having a passive sensor element located at the opposite end of the cavity to the ultrasound transmitter or a means to allow a measured fluid inside the cavity, an antenna for receiving radio frequency signals (f₁, f₂), and a connecting means connecting the antenna to the ultrasound transmitter for using the radio frequency signals for providing energy for driving the ultrasound transmitter,

wherein the antenna for receiving radio frequency signals (f₁, f₂) is capable of acting as means for sending radio frequency signals (f₃) based on the interaction between the ultrasound transmitter and the cavity.

5. A sensor in accordance with claim 2, wherein the light-construction diaphragm oscillator forms one electrode of the transmitter and a fixed electrode forms another electrode for the ultrasound transmitter and wherein the antenna is electrically connected to said electrodes.

6. A sensor in accordance with claim 5, wherein the ultrasound transmitter of the antenna is electrically connected to said electrodes through a matching circuit.

7. A sensor in accordance with claim 2, wherein the distance of the passive sensor element from the ultrasound transmitter is such that a resonance condition is met.

8. A system for measuring pressure, sound pressure variation, magnetic field, acceleration, shaking, or gas composition, comprising;

at least one ultrasonic sensor having a cavity, an ultrasound transmitter and a passive sensor element sensitive to a parameter to be measured,

a reading device capable of reading a variation in the sensor caused by a change in the parameter to be measured,

wherein the sensor includes at least one antenna for wireless communication with the reading device, and

wherein the reading device includes a means for generating two frequencies and sending them to the at least one sensor, and a means for detecting a third frequency backscattered or reflected from the sensor.

9. A system in accordance with claim 8, wherein at least one of the antennas is a loop antenna.

10. A system in accordance with claim 8, wherein at least one of the antennas is a dipole antenna.

11. A system in accordance with claim 8, wherein in the sensor has a light-construction diaphragm oscillator forming one electrode of the transmitter, and a fixed electrode forms another electrode for the ultrasound transmitter whereby the antenna is electrically connected to said electrodes.

12. A system in accordance with claim 8, wherein the ultrasound transmitter of the sensor is formed by a piezo element.

13. A system in accordance with claim 11, wherein in the sensor the ultrasound transmitter of the antenna is electrically connected to said electrodes through an matching circuit.

14. A system in accordance with claim 8, wherein at least one sensor includes several cavities with different basic frequencies connected to the same antenna in order to give an identity for the sensor unit.

15-20. -20. (canceled)