Pressure based wireless sensor and applications thereof

Patent metadata

Field	Value
Publication number	US-2016257173-A1
Application number	US-201615157723-A
Country	US
Kind code	A1
Filing date	May 18, 2016
Priority date	Sep 29, 2014
Publication date	Sep 8, 2016
Grant date	—

Abstract

A wireless sensor includes an antenna, a tuning circuit, a pressure sensing circuit, a processing module, and a transmitter. Collectively, the pressure sensing circuit, the antenna, and the tuning circuit have one or more radio frequency (RF) characteristics and the pressure sensing circuit causes the RF characteristic(s) to vary with varying sensed pressures. The processing module detects a variance of the RF characteristic(s) from a desired value. In response to the detecting of the variance, the processing module adjusts the tuning circuit to substantially re-establish the desired value of the RF characteristic(s). The processing module generates a message regarding the adjusting of the tuning circuit, wherein a level of the adjusting is representative of a variance of pressure sensed by the pressure sensing circuit. The transmitter transmits the message.

First claim

What is claimed is:

1 . A wireless sensor comprises:
an antenna; a tuning circuit operably coupled to the antenna; a pressure sensing circuit operably coupled at least one of the antenna and the tuning circuit, wherein the antenna, the tuning circuit, and the pressure sensing circuit collective have one or more radio frequency (RF) characteristics and wherein the pressure sensing circuit causes the one or more RF characteristics to vary with varying sensed pressures; a processing module operable to:
detect a variance of the one or more RF characteristics from a desired value of the one or more RF characteristics;
in response to the detecting of the variance, adjust the tuning circuit to substantially re-establish the desired value of the one or more RF characteristics; and
generate a message regarding the adjusting of the tuning circuit, wherein a level of the adjusting of the tuning circuit is representative of a variance of pressure sensed by the pressure sensing circuit; and
a transmitter operably coupled to transmit the message.

2 . The wireless sensor of claim 1 , wherein the pressure sensing circuit comprises:
a variable capacitance circuit that includes a first plate, a second plate, and a dielectric section between the first and second plates, wherein the dielectric section includes one or more diaphragms that, as a result of pressure variations, causes at least one of:
a variance of a distance between the first and second plates; and
a variance of a dielectric property of the dielectric section.

3 . The wireless sensor of claim 2 further comprises:
the dielectric section including a diaphragm puck;
the antenna having a loop shape; and
each of the first and second plates having a semi-circle shape and is proximally positioned to the antenna, wherein the first plate is coupled to the antenna and the second plate is coupled to the tuning circuit.

4 . The wireless sensor of claim 1 , wherein the pressure sensing circuit comprises:
a variable inductance circuit that includes a coil and one or more metallic diaphragms that, as a result of pressure variations, that causes an inductance change of the coil.

5 . The wireless sensor of claim 1 further comprises:
the tuning circuit including a capacitor circuit and an inductor;
the pressure sensing circuit including a diaphragm proximal to a capacitor of the capacitor circuit, wherein, as a result of the varying sensed pressures, the diaphragm changes capacitance of the capacitor; and
the processing module adjusts capacitance of the capacitor circuit to substantially compensate for the change capacitance of the capacitor.

6 . The wireless sensor of claim 1 further comprises:
the tuning circuit including a capacitor and an inductor circuit;
the pressure sensing circuit including a diaphragm proximal to an inductor of the inductor circuit, wherein, as a result of the varying sensed pressures, the diaphragm changes inductance of the inductor; and
to substantially compensate for the change inductance of the inductor, the processing module adjusts one or more of:
capacitance of the capacitor; and
inductance of the inductor circuit.

7 . The wireless sensor of claim 1 , wherein an RF characteristic of the one or more RF characteristics comprises:
an impedance at a frequency; a resonant frequency; a quality factor; and a gain.

8 . The wireless sensor of claim 1 , wherein the processing module is further operable to:
in response to a calibration request at a known pressure, adjust the tuning circuit to establish the desired value of the one or more RF characteristics; and record a level of the adjusting of the tuning circuit to represent a pressure calibration of the wireless sensor.

9 . The wireless sensor of claim 1 further comprises:
a second antenna; and
a power harvesting circuit operably coupled to the second antenna, wherein, when the second antenna receives an RF signal, the power harvesting circuit converts the RF signal into a power supply voltage.

10 . The wireless sensor of claim 1 further comprises:
a temperature sensor operably coupled to the processing module, wherein the temperature sensor senses a temperature of an environment proximal to the wireless sensor, and wherein the processing module includes a sensed temperature within the message.

11 . A passive wireless tire pressure sensor comprises:
an antenna; a tuning circuit operably coupled to the antenna; a pressure sensing circuit operably coupled at least one of the antenna and the tuning circuit, wherein the antenna, the tuning circuit, and the pressure sensing circuit collective have one or more radio frequency (RF) characteristics and wherein the pressure sensing circuit causes the one or more RF characteristics to vary with varying sensed pressures; a second antenna; a power harvesting circuit operably coupled to the second antenna, wherein, when the second antenna receives an RF signal, the power harvesting circuit converts the RF signal into a power supply voltage; a processing module powered via the power supply voltage, wherein the processing module is operable to:
detect a variance of the one or more RF characteristics from a desired value of the one or more RF characteristics;
in response to the detecting of the variance, adjust the tuning circuit to substantially re-establish the desired value of the one or more RF characteristics; and
generate a message regarding the adjusting of the tuning circuit, wherein a level of the adjusting of the tuning circuit is representative of a variance of pressure sensed by the pressure sensing circuit; and
a transmitter powered by the power supply voltage, wherein the transmitter transmits the message.

12 . The passive wireless tire pressure sensor of claim 11 , wherein the pressure sensing circuit comprises:
a variable capacitance circuit that includes a first plate, a second plate, and a dielectric section between the first and second plates, wherein the dielectric section includes one or more diaphragms that, as a result of pressure variations, causes at least one of:
a variance of a distance between the first and second plates; and
a variance of a dielectric property of the dielectric section.

13 . The passive wireless tire pressure sensor of claim 12 further comprises:
the dielectric section including a diaphragm puck;
the antenna having a loop shape; and
each of the first and second plates having a semi-circle shape and is proximally positioned to the antenna, wherein the first plate is coupled to the antenna and the second plate is coupled to the tuning circuit.

14 . The passive wireless tire pressure sensor of claim 11 , wherein the pressure sensing circuit comprises:
a variable inductance circuit that includes a coil and one or more metallic diaphragms that, as a result of pressure variations, that causes an inductance change of the coil.

15 . The passive wireless tire pressure sensor of claim 11 further comprises:
the tuning circuit including a capacitor circuit and an inductor;
the pressure sensing circuit including a diaphragm proximal to a capacitor of the capacitor circuit, wherein, as a result of the varying sensed pressures, the diaphragm changes capacitance of the capacitor; and
the processing module adjusts capacitance of the capacitor circuit to substantially compensate for the change capacitance of the capacitor.

16 . The passive wireless tire pressure sensor of claim 11 further comprises:
the tuning circuit including a capacitor and an inductor circuit;
the pressure sensing circuit includ

Assignees

• Rfmicron Inc

Inventors

• Young Brian David
• Rokhsaz Shahriar
• Hassoun Marwan

Classifications

• H02J50/001

  Energy harvesting or scavenging · CPC title

• B60C23/0474

  Measurement control, e.g. setting measurement rate or calibrating of sensors; Further processing of measured values, e.g. filtering, compensating or slope monitoring · CPC title

• H04W84/18

  Self-organising networks, e.g. ad-hoc networks or sensor networks · CPC title

• H04B5/26

  using coils · CPC title

• H04B5/45

  Transponders · CPC title