Electric field detector system

• US 10,564,200 B2
• Filed: 10/05/2016
• Issued: 02/18/2020
• Est. Priority Date: 10/06/2015
• Status: Active Grant

• Current Assignee: Charles Stark Draper Laboratory Incorporated
• Original Assignee: Charles Stark Draper Laboratory Incorporated
• Inventors: Bickford, James A., Weinberg, Marc S., Fullford, John Shattler, McNabb, Jr., Ronald Steven
• Primary Examiner(s): Phan, Huy Q
• Assistant Examiner(s): Ferdous, Zannatul
• Application Number:
  US15/286,163
• Publication Number:
  US 20170097382A1
• Time in Patent Office: 1,231 Days
• CPC Class Codes: A61B 2560/0252 using ambient temperature
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/24 Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
• CPC Class Codes: A61B 5/291 for electroencephalography [EEG]
• CPC Class Codes: G01R 29/0814 Field measurements related to measuring influence on or from apparatus, components or humans EMC, EMI and similar testing in general G01R31/001, e.g. in ESD, EMI, EMC, EMP testing, measuring radiation leakage; detecting presence of micro- or radiowave emitters; dosimetry; testing shielding; measurements related to lightning
• CPC Class Codes: G01R 29/0878 Sensors; antennas; probes; detectors wave guide measuring sections G01R1/24

Abstract

Aspects and embodiments are generally directed to electric field detector systems and methods. In one example, an electric field detector system includes a proof-mass including a source of concentrated charge, a plurality of supports, each individual support of the plurality supports being coupled to the proof-mass, a plurality of sensors, each individual sensor of the plurality of sensors positioned to measure a resonant frequency of a corresponding support of the plurality of supports, and a controller coupled to each individual sensor of the plurality of sensors, the controller configured to measure a characteristic of an electric field imparted on the proof-mass based on at least a first resonant frequency of the measured resonant frequencies.

Claims

1. An electric field detector system comprising:

a proof-mass including a source of concentrated charge configured to generate an electric dipole that produces a torque on the proof-mass in response to an electric field;

a plurality of supports, each individual support of the plurality supports being coupled to the proof-mass and having a resonant frequency affected by the electric field;

a plurality of sensors, each individual sensor of the plurality of sensors positioned to measure the resonant frequency of a corresponding support of the plurality of supports; and

a controller coupled to each individual sensor of the plurality of sensors, the controller configured to measure an electric field strength of the electric field by comparing at least a first measured resonant frequency of the measured resonant frequencies to a first frequency reference to measure the torque on the proof-mass.

2. The electric field detector system of claim 1, wherein the controller is further configured to determine a linear force imparted on the proof-mass, in a first direction, based on at least the first resonant frequency of the measured resonant frequencies.

3. The electric field detector system of claim 1, wherein the controller is further configured to determine a temperature based on a common mode signal generated from a comparison of each of the measured resonant frequencies.

4. The electric field detector system of claim 1, wherein the first frequency reference is a natural frequency of the corresponding support.

5. The electric field detector system of claim 1, wherein the plurality of supports includes a first support coupled to a first side of the proof-mass and having the first resonant frequency, a second support coupled to a second side of the proof-mass and having a second resonant frequency, a third support coupled to the first side of the proof-mass and having a third resonant frequency, and a fourth support coupled to the second side of the proof-mass and having a fourth resonant frequency.

6. The electric field detector system of claim 5, wherein the controller is further configured to determine a first linear force imparted on the proof-mass, in a first direction, and a second linear force imparted on the proof-mass, in a second direction, based on the first resonant frequency, the second resonant frequency, the third resonant frequency, and the fourth resonant frequency, and determine a temperature based on a common mode signal generated from a comparison of each of the first resonant frequency, the second resonant frequency, the third resonant frequency, and the fourth resonant frequency.

7. The electric field detector system of claim 1, wherein the source of concentrated charge includes a polarized ferro-electric material including Lithium Niobate.

8. The electric field detector system of claim 1, wherein the source of concentrated charge includes an electret.

9. The electric field detector system of claim 8, wherein the electret includes a plurality of stacked electrets.

10. The electric field detector system of claim 1, wherein each sensor of the plurality of sensors includes a comb drive including a first electrode configured to apply a voltage to a comb positioned on the corresponding support, and a second electrode configured to measure a change in a capacitance between the first electrode and the second electrode, wherein the controller is further configured to infer the resonant frequency of the corresponding support based at least in part on the change in the capacitance.

11. The electric field detector system of claim 1, further comprising a field concentrator located adjacent a side of the proof-mass, wherein the field concentrator is positioned so as to focus the electric field on the proof-mass.

12. The electric field detector system of claim 1, further comprising a plurality of geometric isolation structures interposed between the proof-mass and each of the plurality of supports, each geometric isolation structure being positioned to isolate a respective support from a differential thermal strain between the proof-mass and the respective support.

13. The electric field detector system of claim 1, further comprising an internal isolation structure extending through the proof-mass and configured to suspend the proof-mass relative to a system substrate, the internal isolation structure being positioned to isolate the plurality of supports from a differential thermal strain between the proof-mass and the plurality of supports.

14. An electric field transduction method comprising:

generating an electric dipole at a proof-mass coupled to a plurality of supports;

receiving an electric field at the proof-mass;

measuring a resonant frequency of each individual support of the plurality of supports; and

determining an electric field strength of the electric field based on at least one measured resonant frequency of the measured resonant frequencies by comparing the at least one resonant frequency to a frequency reference and, based on the comparison, determining a torque imparted on the proof-mass by the electric field.

15. The method according to claim 14, further comprising determining a variability of the electric field based on the at least one measured resonant frequency.

16. The method according to claim 14, further comprising determining a linear force imparted on the proof-mass, in a first direction, based on the at least one measured resonant frequency of the measured resonant frequencies.

17. The method according to claim 14, further comprising determining a temperature based on a common mode signal generated from a comparison of each of the measured resonant frequencies.

18. The method according to claim 14, further comprising determining a force of acceleration imparted on the proof-mass based on the at least one measured resonant frequency of the measured resonant frequencies of the individual supports.

19. The method according to claim 14, wherein the measured resonant frequency of each individual support of the plurality of supports includes a natural frequency.

20. The method according to claim 14, wherein the plurality of supports includes a first support having a first resonant frequency, a second support having a second resonant frequency, a third support having a third resonant frequency, and a fourth support having a fourth resonant frequency, and wherein the method further comprises:

determining a first linear force imparted on the proof-mass, in a first direction, based on the first resonant frequency, the second resonant frequency, the third resonant frequency, and the fourth resonant frequency;

determining a second linear force imparted on the proof-mass, in a second direction, based on the first resonant frequency, the second resonant frequency, the third resonant frequency, and the fourth resonant frequency; and

determining a temperature based on a common mode signal generated from a comparison of each of the first resonant frequency, the second resonant frequency, the third resonant frequency, and the fourth resonant frequency.