Microdischarge-based transducer

• US 10,006,823 B2
• Filed: 06/20/2014
• Issued: 06/26/2018
• Est. Priority Date: 06/20/2013
• Status: Active Grant

• Current Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Original Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Inventors: Gianchandani, Yogesh, Eun, Christine, Luo, Xin, Kushner, Mark, Xiong, Zhongmin, Wang, Jun-Chieh
• Primary Examiner(s): West, Paul
• Application Number:
  US14/899,632
• Publication Number:
  US 20160138991A1
• Time in Patent Office: 1,467 Days
• CPC Class Codes: E21B 47/06 Measuring temperature or pressure
• CPC Class Codes: G01L 9/0042 Constructional details associated with semiconductive diaphragm sensors, e.g. etching, or constructional details of non-semiconductive diaphragms details about the integration or bonding of piezoresistor in or on the diaphragm G01L9/0052 and G01L9/0057 respectively
• CPC Class Codes: G01L 9/0051 using variations in ohmic resistance
• CPC Class Codes: G01L 9/0072 using variations in capacitance
• CPC Class Codes: G01L 9/0073 using a semiconductive diaphragm

Abstract

The distance between microscale electrodes can be determined from microdischarge current and/or capacitance distribution among a plurality of electrodes. A microdischarge-based pressure sensor includes a reference pair of electrodes on a body of the sensor and a sensing pair of electrodes. One of the electrodes of the sensing pair is on a diaphragm of the sensor so that the distance between the sensing pair of electrodes changes with diaphragm movement, while the distance between the reference pair does not. Plasma and current distribution within a microdischarge chamber of the sensor is sensitive to very small diaphragm deflections. Pressure sensors can be fabricated smaller than ever before, with useful signals from 50 micron diaphragms spaced only 3 microns from the sensor body. The microdischarge-based sensor is capable of operating in harsh environments and can be fabricated along-side similarly configured capacitive sensors.

Claims

1. A sensor, comprising:

a sensor body;

a diaphragm supported in spaced apart relation to the sensor body and facing the sensor body across a gap; and

a plurality of electrodes, each of which is attached to the sensor body or to the diaphragm at the gap and arranged such that, when the diaphragm deflects relative to the sensor body, the distance between a first pair of the electrodes changes, and the distance between a second pair of the electrodes does not change, wherein the first pair of electrodes includes a cathode on the sensor body and a sensing anode on the diaphragm, and the second pair of electrodes includes the cathode and a reference anode on the sensor body.

2. A sensor as defined in claim 1, further comprising a spacer located between the sensor body and the diaphragm and partly defining a sealed chamber having a perimeter that surrounds the plurality of electrodes.

3. A sensor as defined in claim 2, wherein the sealed chamber is a microdischarge chamber that contains a plasma when an ionizing voltage is applied across the pairs of electrodes.

4. A sensor as defined in claim 1, further comprising electrical contacts accessible at an exterior of the sensor and through-glass vias (TGVs) electrically connecting the electrical contacts with the plurality of electrodes through the thickness of the sensor body.

5. A sensor as defined in claim 1, further comprising electrical contacts accessible at an exterior of the sensor, wherein the sensor body comprises a doped semi-conductor layer electrically connecting the electrical contacts with the plurality of electrodes through the thickness of the sensor body.

6. A sensor as defined in claim 1 configured to be capable of operation in a micro discharge mode and in a capacitive mode.

7. A sensor as defined in claim 1, wherein the second pair of electrodes includes the cathode and the reference anode on the sensor body, the cathode having a plasma-concentrating feature that extends toward a plasma-concentrating feature of the reference anode to define a minimum gap between opposing edges of the cathode and the reference anode.

8. A method of determining fluid pressure in a subterranean cavity, comprising the step of receiving information related to the amount of deflection of a diaphragm of a sensor immersed in a fluid located in the subterranean cavity, the sensor comprising a plurality of electrodes arranged in a sealed chamber such that the distance between a first pair of the electrodes changes more than the distance between a second pair of the electrodes when the amount of deflection of the diaphragm changes, wherein said information indicates the distribution of an electrical property among the plurality of electrodes in response to a voltage applied to the plurality of electrodes, wherein both of the second pair of electrodes are positioned on a body of the sensor equal distances from the diaphragm, wherein the sensor is a microdischarge-based sensor and said information includes differential current, defined as the ratio of:

the difference in the current flow between the two pairs of electrodes, to the sum of the current flow between the two pairs of electrodes.

9. The method of claim 8, wherein the step of receiving information includes receiving information related to the amount of deflection of each of a plurality of diaphragms of a corresponding plurality of sensors immersed in the fluid and dispersed in the subterranean cavity, each sensor comprising a plurality of electrodes arranged in a sealed chamber such that the distance between a first pair of electrodes of each sensor changes more than the distance between a second pair of electrodes of each sensor when the amount of deflection of each diaphragm changes, wherein said information indicates the distribution of an electrical property among the plurality of electrodes of each sensor in response to a voltage applied to the plurality of electrodes of each sensor.

10. A method of determining fluid pressure in a subterranean cavity, comprising the step of receiving information related to the amount of deflection of a diaphragm of a sensor immersed in a fluid located in the subterranean cavity, the sensor comprising a plurality of electrodes arranged in a sealed chamber such that the distance between a first pair of the electrodes changes more than the distance between a second pair of the electrodes when the amount of deflection of the diaphragm changes, wherein said information indicates the distribution of an electrical property among the plurality of electrodes in response to a voltage applied to the plurality of electrodes, wherein both of the second pair of electrodes are positioned on a body of the sensor equal distances from the diaphragm, wherein the sensor is a capacitive sensor and said information is based on a comparison of the capacitance between the first pair of electrodes and the capacitance between the second pair of electrodes.

11. A method of determining fluid pressure in a subterranean cavity, comprising the step of receiving information related to the amount of deflection of a diaphragm of a sensor immersed in a fluid located in the subterranean cavity, the sensor comprising a plurality of electrodes arranged in a sealed chamber such that the distance between a first pair of the electrodes changes more than the distance between a second pair of the electrodes when the amount of deflection of the diaphragm changes, wherein said information indicates the distribution of an electrical property among the plurality of electrodes in response to a voltage applied to the plurality of electrodes, wherein both of the second pair of electrodes are positioned on a body of the sensor equal distances from the diaphragm, wherein the first pair of electrodes includes a cathode on the sensor body and a sensing anode on the diaphragm, and the second pair of electrodes includes the cathode and a reference anode on the sensor body.

12. A method of determining fluid pressure in a subterranean cavity, comprising the step of receiving information related to the amount of deflection of a diaphragm of a sensor immersed in a fluid located in the subterranean cavity, the sensor comprising a plurality of electrodes arranged in a sealed chamber such that the distance between a first pair of the electrodes changes more than the distance between a second pair of the electrodes when the amount of deflection of the diaphragm changes, wherein said information indicates the distribution of an electrical property among the plurality of electrodes in response to a voltage applied to the plurality of electrodes, wherein both of the second pair of electrodes are positioned on a body of the sensor equal distances from the diaphragm, wherein the first pair of electrodes includes an anode on the sensor body and a sensing cathode on the diaphragm, and the second pair of electrodes includes the anode and a reference cathode on the sensor body.

13. A sensor, comprising:

a sensor body;

a diaphragm supported in spaced apart relation to the sensor body and facing the sensor body across a gap; and

a plurality of electrodes, each of which is attached to the sensor body or to the diaphragm at the gap and arranged such that, when the diaphragm deflects relative to the sensor body, the distance between a first pair of the electrodes changes, and the distance between a second pair of the electrodes does not change, wherein both of the second pair of electrodes are positioned on a body of the sensor equal distances from the diaphragm, wherein the first pair of electrodes includes an anode on the sensor body and a sensing cathode on the diaphragm, and the second pair of electrodes includes the anode and a reference cathode on the sensor body.

14. A sensor, comprising:

a sensor body;

a diaphragm supported in spaced apart relation to the sensor body and facing the sensor body across a gap; and

a plurality of electrodes, each of which is attached to the sensor body or to the diaphragm at the gap and arranged such that, when the diaphragm deflects relative to the sensor body, the distance between a first pair of the electrodes changes, and the distance between a second pair of the electrodes does not change, wherein both of the second pair of electrodes are positioned on a body of the sensor equal distances from the diaphragm, wherein the sensor is a microdischarge-based sensor, wherein the sensor is configured to receive information related to an amount of deflection of the diaphragm of the sensor immersed in a fluid, and said information includes differential current, defined as the ratio of;

the difference in the current flow between the two pairs of electrodes, to the sum of the current flow between the two pairs of electrodes.

15. A sensor, comprising:

a sensor body;

a diaphragm supported in spaced apart relation to the sensor body and facing the sensor body across a gap; and

a plurality of electrodes, each of which is attached to the sensor body or to the diaphragm at the gap and arranged such that, when the diaphragm deflects relative to the sensor body, the distance between a first pair of the electrodes changes, and the distance between a second pair of the electrodes does not change, wherein both of the second pair of electrodes are positioned on a body of the sensor equal distances from the diaphragm, wherein the sensor is a capacitive sensor, wherein the sensor is configured to receive information related to an amount of deflection of the diaphragm of the sensor immersed in a fluid, and said information is based on a comparison of the capacitance between the first pair of electrodes and the capacitance between the second pair of electrodes.