# US 9,752,900 B2 · Multi-plate capacitive transducer

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- Number: US 9,752,900 B2
- Document ID: US9752900B2
- Status: Granted
- Kind: B2
- Application number: 14/796,266
- Filed: 2015-07-10
- Published: 2017-01-12
- Granted: 2017-09-05
- Earliest claimed: 2015-07-10
- Assignees: Wyrobek International, Inc.
- Applicants: Wyrobek International, Inc.
- Inventors: Jerzy Wyrobek
- Web page: https://patentgrep.com/patent/US9752900B2

## CPC

- G01D 5/2417: {by varying separation}
- G01D 5/24: by varying capacitance
- G01H 11/06: by electric means
- G01L 1/148: {using semiconductive material, e.g. silicon}
- G01P 15/0802: {Details}
- G01P 15/125: by capacitive pick-up
- G01R 27/2605: {Measuring capacitance (capacitive sensors G01D5/24)}
- G01N 3/42: by performing impressions under a steady load by indentors, e.g. sphere, pyramid (G01N3/54 takes precedence)
- G01N 2203/0286: Miniature specimen; Testing on microregions of a specimen
- G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01H: MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G)
- G01P: MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT (measuring or recording blood flow A61B5/02, A61B8/06; monitoring speed or deceleration of electrically-propelled vehicles B60L3/00; vehicle lighting systems adapted to indicate speed B60Q1/54; determining position or course in navigation, measuring ground distance in geodesy or surveying G01C; combined measuring devices for measuring two or more variables of movement G01C23/00; measuring velocity of sound G01H; measuring velocity of light G01J7/00; measuring direction or velocity of solid objects by reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation, G01S; measuring speed of nuclear radiation G01T; measuring acceleration of gravity G01V; {measuring or recording the speed of trains B61L23/00; speed indicators incorporated in motor vehicles B60K35/00; measuring frequency or phase G01R; traffic control G08G})
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

A capacitive transducer includes first and second fixed outer plates, each having fixed electrodes positioned on inner surfaces, and a center plate assembly positioned between the fixed outer plates. The center plate assembly includes a top center plate and bottom center plate. The top and bottom center plates each have an inner section, an outer frame positioned outward of a perimeter of the inner section, a set of springs connecting the outer frame to the inner section, and a center electrode positioned on an outer surface of the inner section. The set of springs has thickness less than each of the inner section and the outer frame. The center electrodes of the top and bottom center plates are connected to become electrically one electrode.

## Claims

### Claim 1

A capacitive transducer comprising:
a first fixed outer plate having a first fixed electrode positioned on an inner surface;
a second fixed outer plate having a second fixed electrode positioned on an inner surface; and
a center plate assembly positioned between the first and second fixed outer plates, the center plate assembly comprising:
a top center plate comprising:
a first silicon substrate;
a first inner section of the first silicon substrate;
a first outer frame of the first silicon substrate positioned outward of a perimeter of the first inner section, wherein a first raised spacer member is integrally formed with the first outer frame and extends upward from an outer surface of the first outer frame;
a first set of springs of the first silicon substrate connecting the first outer frame to the first inner section, wherein the first set of springs has thickness less than each of the first inner section and the first outer frame; and
a first center electrode positioned on an outer surface of the first inner section; and
a bottom center plate comprising:
a second silicon substrate;
a second inner section of the second silicon substrate;
a second outer frame of the second silicon substrate positioned outward of a perimeter of the second inner section, wherein a second raised spacer member is integral with the second outer frame and extends downward from an outer surface of the second outer frame;
a second set of springs of the second silicon substrate connecting the second outer frame to the second inner section, wherein the second set of springs has a thickness less than each of the second inner section and the second outer frame;
a second center electrode positioned on an outer surface of the second inner section, wherein the second center electrode and the first center electrode are connected to form a single electrode, and wherein the bottom center plate is a mirror image of the top center plate.

### Claim 2 (depends on 1)

The capacitive transducer of claim 1, wherein the first and second spacer members each have a width less than a width of each of the first and second outer frames, and wherein the first and second spacer members are located in closer proximity to an outer perimeter of the first and second outer frames than to an inner perimeter of the first and second outer frames.

### Claim 3 (depends on 2)

The capacitive transducer of claim 2, wherein the first and second fixed outer plates each further comprise:
an outer and inner shield electrode, wherein the outer shield electrodes cover an outer surface of each of the first and second fixed outer plates and the inner shield electrodes form a partial perimeter around the first and second fixed electrodes and are positioned inward of the respective spacer members upon assembly.

### Claim 4 (depends on 1)

The capacitive transducer of claim 1, wherein the first and second spacer members each have a thickness greater than the thickness of the first and second set of springs, respectively, and less than the thickness of each of the first and second outer frames and first and second inner sections.

### Claim 5 (depends on 1)

The capacitive transducer of claim 1, wherein the first inner section further comprises:
a plurality of tabs, each of the plurality of tabs extending from a different corner of the first inner section toward the first outer frame.

### Claim 6 (depends on 5)

The capacitive transducer of claim 5, wherein the first set of springs comprises a plurality of springs, each of the plurality of springs emanating from a different side of an inner perimeter of the first outer frame and extending along a length of the first inner section before joining a tab of the first inner section.

### Claim 7 (depends on 6)

The capacitive transducer of claim 6, wherein the thickness of the first set of springs is reduced from an inner surface of the top center plate, and wherein an outer surface of the first set of springs shares a plane with a portion of the outer surface of the plurality of tabs and the first outer frame.

### Claim 8 (depends on 7)

The capacitive transducer of claim 7, wherein the top center plate further comprises:
a connection terminal extending from the first outer frame; and
an electrical lead connecting the first center electrode to the connection terminal, wherein the electrical lead is deposited on the outer surface of at least one spring within the first set of springs.

### Claim 9 (depends on 7)

The capacitive transducer of claim 7, wherein each spring within the first set of springs is substantially centered between the first inner section and the first outer frame.

### Claim 10 (depends on 1)

The capacitive transducer of claim 1, wherein the first and second fixed outer plates and the top and bottom center plates of the center plate assembly each further comprise:
a centrally located hole that extends through a full thickness of the plate, wherein the hole in each of the top and bottom center plates has a diameter smaller than a diameter of the hole in each of the first and second fixed outer plates.

### Claim 11 (depends on 1)

The capacitive transducer of claim 1, wherein the first and second fixed electrodes and first and second center electrodes each comprise a layer of conducting material that has been deposited on the first fixed outer plate, second fixed outer plate, top center plate, and bottom center plate, respectively.

### Claim 12

A capacitive transducer comprising:
a first fixed outer plate having a first fixed electrode positioned on an inner surface;
a second fixed outer plate having a second fixed electrode positioned on an inner surface;
a center plate assembly positioned between the first and second fixed outer plates and comprising:
a top center plate comprising:
a first silicon substrate;
a first inner section of the first silicon substrate;
a first outer frame of the first silicon substrate positioned outward of a perimeter of the first inner section, wherein a first raised spacer member is integrally formed with the first outer frame and extends upward from an outer surface of the first outer frame;
a first set of springs of the first silicon substrate connecting the first outer frame to the first inner section; and
a first center electrode positioned on an outer surface of the first inner section; and
a bottom center plate comprising:
a second silicon substrate;
a second inner section of the second silicon substrate;
a second outer frame of the second silicon substrate positioned outward of a perimeter of the second inner section, wherein a second raised spacer member is integrally formed with the second outer frame and extends downward from an outer surface of the second outer frame;
a second set of springs of the second silicon substrate connecting the second outer frame to the second inner section; and
a second center electrode positioned on an outer surface of the second inner section, wherein the second center electrode and the first center electrode are connected to form a single electrode;
wherein the bottom center plate is a mirror image of the top center plate, and an inner surface of the top center plate and an inner surface of the bottom center plate are bonded together.

### Claim 13 (depends on 12)

The capacitive transducer of claim 12, wherein the first set of springs has a thickness less than a thickness of each of the first spacer member, first outer frame, and first inner section, and wherein the first set of springs shares a plane with a portion of the outer surface of the first outer frame.

### Claim 14 (depends on 13)

The capacitive transducer of claim 13, wherein the first inner section further comprises:
a plurality of tabs, each of the plurality of tabs extending from a different corner of the first inner section toward the first outer frame.

### Claim 15 (depends on 14)

The capacitive transducer of claim 14, wherein the first set of springs comprises a plurality of springs, each of the plurality of springs emanating from a different side of an inner perimeter of the first outer frame and extending along a length of the first inner section before joining a tab of the first inner section.

### Claim 16 (depends on 13)

The capacitive transducer of claim 13, wherein the first spacer member has a thickness greater than the thickness of the first set of springs and less than the thickness of each of the first outer frame and first inner section.

### Claim 17

A method of assembling a capacitive transducer comprising the steps of:
providing silicon substrates to be fabricated as top and bottom center plates;
etching an outer surface of each of a top and bottom center plate to form a raised spacer member along a perimeter of the outer surface of each of the top and bottom center plates;
etching through a full thickness of each of the top and bottom center plates to create an outer frame, inner section, and a plurality of springs connecting the outer frame to the inner section;
depositing a layer of conducting material on an outer surface of the inner section of each of the top and bottom center plates;
depositing a layer of conducting material on an outer surface of at least one of the plurality of springs on each of the top and bottom center plates to connect a center electrode on the inner section to a connection terminal on the outer frame;
depositing a layer of conducting material on an inner surface of a first fixed outer plate and an inner surface of a second fixed outer plate;
etching through a full thickness of a portion of each of the top and bottom center plates and the first and second fixed outer plates to create a centrally-located hole;
glass frit bonding the first and second center plates together; and
glass frit bonding the spacer members to the inner surfaces of the first and second fixed outer plates.

### Claim 18 (depends on 17)

The method of claim 17, further comprising the steps of:
etching through a partial thickness of the plurality of springs to reduce a thickness of the plurality of springs, wherein etching comprises removing material from the silicon substrate; and
depositing a layer of conducting material on an outer surface of the first and second fixed outer plates.