# US 12,000,739 B2 · Lever based differential capacitive strain gauge with acceleration rejection

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- Number: US 12,000,739 B2
- Document ID: US12000739B2
- Status: Granted
- Kind: B2
- Application number: 17/238,051
- Filed: 2021-04-22
- Published: 2022-10-27
- Granted: 2024-06-04
- Earliest claimed: 2021-04-22
- Assignees: Analog Devices, Inc.
- Applicants: Analog Devices, Inc.
- Inventors: Erdinc Tatar; William A. Clark
- Web page: https://patentgrep.com/patent/US12000739B2

## CPC

- G01L 1/148: {using semiconductive material, e.g. silicon}
- G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G)

## Abstract

Microelectromechanical systems (MEMS) capacitive strain gauge sensors are described. The strain gauge sensors include a lever configured to mechanically amplify a strain response. In some embodiments, an anchored beam is coupled to the effort arm of the lever and a movable sensing finger to the resistance arm. The effort arm may be shorter than the resistance arm, thus providing a mechanical amplification.

## Claims

### Claim 1

A microelectromechanical systems (MEMS) strain gauge sensor, comprising:
a lever configured to rotate about a fulcrum;
an anchor coupled to a first end of the lever; and
a movable sense finger coupled to a second end of the lever,
wherein the first end of the lever is closer to the fulcrum than the second end of the lever.

### Claim 2 (depends on 1)

The strain gauge sensor of claim 1, further comprising a fixed sense finger, wherein the movable sense finger and fixed sense finger are configured to form a capacitor.

### Claim 3 (depends on 1)

The strain gauge sensor of claim 1, wherein the lever is a first lever, the anchor is a first anchor, the movable sense finger is a first movable sense finger, and wherein the strain gauge sensor further comprises a second lever, second anchor, and second movable sense finger, wherein the second lever is coupled to an opposite end of the fulcrum than the first lever and is configured to rotate about the fulcrum, wherein the second anchor is coupled to a first end of the second lever and the second movable sense finger is coupled to a second end of the second lever.

### Claim 4 (depends on 3)

The strain gauge sensor of claim 3, further comprising third and fourth levers, and third and fourth movable sense fingers, wherein the first anchor is coupled to a first end of the third lever and the second anchor is coupled to a first end of the fourth lever, and wherein the third movable sense finger is coupled to a second end of the third lever and the fourth movable sense finger is coupled to a second end of the fourth lever.

### Claim 5 (depends on 1)

A multi-axis strain gauge sensor comprising: at least two strain gauge sensors of claim 1, configured to detect strain in orthogonal directions relative to each other.

### Claim 6 (depends on 1)

The strain gauge sensor of claim 1, sensor is configured to provide mechanical amplification greater than 2.

### Claim 7 (depends on 1)

The strain gauge sensor of claim 1, further comprising anchored parallel beams capacitively coupled to the movable sense finger.

### Claim 8

A microelectromechanical systems (MEMS) strain gauge sensor, comprising:
a substrate;
an anchor rigidly coupled to the substrate;
an effort arm of a lever coupled to the anchor by a beam;
a resistance arm of the lever coupled to a movable capacitive sense finger; and
a fixed capacitive sense finger, wherein the movable capacitive sense finger and fixed capacitive sense finger form a sensing capacitor.

### Claim 9 (depends on 8)

The strain gauge sensor of claim 8, wherein the resistance arm of the lever is coupled to the movable capacitive sense finger by a beam.

### Claim 10 (depends on 8)

The strain gauge sensor of claim 8, wherein the lever is a first lever, the anchor is a first anchor, the movable capacitive sense finger is a first movable capacitive sense finger, and wherein the strain gauge sensor further comprises a second lever, second anchor, and second movable capacitive sense finger, wherein the first and second levers are configured to rotate about a common fulcrum, and wherein the second anchor is coupled to an effort arm of the second lever and the second movable capacitive sense finger is coupled to a resistance arm of the second lever.

### Claim 11 (depends on 10)

The strain gauge sensor of claim 10, further comprising third and fourth levers, and third and fourth movable capacitive sense fingers, wherein the first anchor is coupled to an effort arm of the third lever and the second anchor is coupled to an effort arm of the fourth lever, and wherein the third movable sense finger is coupled to a resistance arm of the third lever and the fourth movable sense finger is coupled to a resistance arm of the fourth lever.

### Claim 12 (depends on 8)

A multi-axis strain gauge sensor comprising: at least two strain gauge sensors of claim 8, configured to detect strain in orthogonal directions relative to each other.

### Claim 13 (depends on 8)

The strain gauge sensor of claim 8, wherein the resistance arm of the lever is between 10% and 500% longer than the effort arm of the lever.

### Claim 14 (depends on 8)

The strain gauge sensor of claim 8, further comprising anchored parallel beams capacitively coupled to the movable capacitive sense finger.

### Claim 15

A microelectromechanical systems (MEMS) capacitive strain gauge sensor, comprising:
a substrate;
an anchor rigidly coupled to the substrate;
a lever having an effort arm and a resistance arm;
a beam rigidly coupling the anchor to the effort arm;
a movable capacitor electrode; and
a beam rigidly coupling the movable capacitor electrode to the resistance arm of the lever.

### Claim 16 (depends on 15)

The MEMS capacitive strain gauge sensor of claim 15, further comprising a fixed capacitor electrode configured to form a variable capacitor with the movable capacitor electrode.

### Claim 17 (depends on 15)

The MEMS capacitive strain gauge sensor of claim 15, wherein the lever is a first lever, the anchor is a first anchor, the movable capacitor electrode is a first movable capacitor electrode, and wherein the MEMS capacitive strain gauge sensor further comprises a second lever, second anchor, and second movable capacitor electrode, wherein the first and second levers are configured to rotate about a same fulcrum, and wherein the second anchor is coupled to an effort arm of the second lever and the second movable capacitor electrode is coupled to a resistance arm of the second lever.

### Claim 18 (depends on 17)

The MEMS capacitive strain gauge sensor of claim 17, further comprising third and fourth levers, and third and fourth movable capacitor electrodes, wherein the first anchor is coupled to an effort arm of the third lever and the second anchor is coupled to an effort arm of the fourth lever, and wherein the third movable capacitor electrode is coupled to a resistance arm of the third lever and the fourth movable capacitor electrode is coupled to a resistance arm of the fourth lever.

### Claim 19 (depends on 15)

A multi-axis strain gauge sensor comprising: at least two strain gauge sensors of claim 15, configured to detect strain in orthogonal directions relative to each other.

### Claim 20 (depends on 15)

The MEMS capacitive strain gauge sensor of claim 15, wherein the resistance arm of the lever is between 10% and 500% longer than the effort arm of the lever.