# US 9,752,941 B2 · Pressure sensor and pressure sensing method

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- Number: US 9,752,941 B2
- Document ID: US9752941B2
- Status: Granted
- Kind: B2
- Application number: 14/018,505
- Filed: 2013-09-05
- Published: 2014-03-06
- Granted: 2017-09-05
- Earliest claimed: 2012-09-05
- Assignees: Samsung Electronics Co., Ltd.; Sungkyunkwan University Foundation for Corporate Collaboration
- Applicants: Samsung Electronics Co., Ltd.; Sungkyunkwan University Foundation for Corporate Collaboration
- Inventors: Sang-hun Jeon; Jong-jin Park; Thanh Tien Nguyen; Ji-hyun Bae; Kyung-eun Byun; Nae-eung Lee; Do-il Kim; Quang Trung Tran
- Web page: https://patentgrep.com/patent/US9752941B2

## CPC

- G01L 1/16: using properties of piezoelectric devices
- H10D 48/50: Devices controlled by mechanical forces, e.g. pressure
- G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G)
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

A pressure sensor and a pressure sensing method are provided. The pressure sensor includes a substrate; a sensor thin film transistor (TFT) disposed on the substrate and including a gate insulating layer, wherein the gate insulating layer includes an organic matrix in which piezoelectric inorganic nano-particles are dispersed; a power unit configured to apply an alternating current (AC) signal to a gate of the sensor TFT; and a pressure sensing unit configured to obtain a remnant polarization value based on a drain current which is generated in response to the AC signal and detected by the sensor TFT, and to sense a pressure based on the remnant polarization value.

## Claims

### Claim 1

A pressure sensor comprising:
a substrate;
a sensor thin film transistor (TFT) disposed on the substrate and comprising a gate insulating layer, wherein the gate insulating layer comprises an organic matrix in which piezoelectric inorganic nano-particles are dispersed;
a power unit configured to apply an alternating current (AC) signal to a gate of the sensor TFT; and
a pressure sensing unit configured to obtain a remnant polarization value based on a drain current which is generated in response to the AC signal and detected by the sensor TFT, and to sense pressure based on the remnant polarization value.

### Claim 2 (depends on 1)

The pressure sensor of claim 1, wherein when an amplitude of the AC signal applied to the gate is VGamp, an amplitude of the drain current is IDamp, and an average drain current value is IDmean, the remnant polarization value is in proportion to a value of
V
G
amp
⁢
⁢
I
D
mean
I
D
amp
,
and the pressure sensor is configured to sense the pressure by using a variation in the remnant polarization value.

### Claim 3 (depends on 1)

The pressure sensor of claim 1, wherein the AC signal has a frequency ranging from about 0.001 Hz to about 1 GHz.

### Claim 4 (depends on 1)

The pressure sensor of claim 1, wherein a voltage amplitude of the AC signal ranges from 0.01 V to 100 V.

### Claim 5 (depends on 1)

The pressure sensor of claim 1, wherein the organic matrix comprises a piezoelectric organic material.

### Claim 6 (depends on 5)

The pressure sensor of claim 5, wherein the piezoelectric organic material is selected from P(VDF-TrFE), P(VDF-TrFE-CFE), and P(VDF-TrFE-CtFE).

### Claim 7 (depends on 5)

The pressure sensor of claim 5, wherein the organic matrix has a crystalline structure.

### Claim 8 (depends on 5)

The pressure sensor of claim 5, wherein the piezoelectric inorganic nano-particles are selected from the group consisting of gallium orthophosphate (GaPO4), langasite (La3Ga5SiO14), a quartz analogic crystal, barium titanate (BaTiO3), lead titanate (PbTiO3), lead zirconate titanate (Pb[ZrxTi1-x]O3 (0≦x≦1), potassium niobate (KNbO3), lithium niobate (LiNbO3), lithium tantalate (LiTaO3), sodium tungstate (Na2WO3), zinc oxide (Zn2O3), Ba2NaNb5O5, Pb2KNb5O15, sodium potassium niobate ((K,Na)NbO3), bismuth ferrite (BiFeO3), sodium niobate (NaNbO3), bismuth titanate (Bi4Ti3O12), and sodium bismuth titanate (Na0.5Bi0.5TiO3).

### Claim 9 (depends on 1)

The pressure sensor of claim 1, further comprising a switching TFT that is electrically connected to the sensor TFT, wherein a sensor pixel structure of the pressure sensor comprises one switching TFT and one sensor TFT.

### Claim 10 (depends on 1)

The pressure sensor of claim 1, wherein the organic matrix has a crystalline structure.

### Claim 11 (depends on 10)

The pressure sensor of claim 10, wherein the organic matrix is formed to have the crystalline structure through an annealing process which implements a temperature of 120° C. or higher.

### Claim 12 (depends on 1)

The pressure sensor of claim 1, wherein the substrate is a flexible substrate, wherein the substrate is formed of a material including polyimide.

### Claim 13

A pressure sensing method comprising:
applying an alternating current (AC) signal to a gate of a sensor thin film transistor (TFT) comprising a piezoelectric gate insulating layer;
detecting a drain current from the sensor TFT, the drain current being generated in response to the AC signal;
obtaining a remnant polarization value based on the drain current; and
sensing a pressure based on the remnant polarization value,
wherein when an amplitude of the AC signal applied to the gate is VGamp, an amplitude of the drain current is IDamp, and an average drain current value is IDmean, the remnant polarization value is in proportion to a value of
V
G
amp
⁢
⁢
I
D
mean
I
D
amp
,
and the sensing the pressure comprises sensing the pressure by using a variation in the remnant polarization value.

### Claim 14 (depends on 13)

The pressure sensing method of claim 13, wherein the AC signal has a frequency from about 0.001 Hz to about 1 GHz.

### Claim 15 (depends on 13)

The pressure sensing method of claim 13, wherein a voltage amplitude of the AC signal ranges from 0.01 V to 100 V.

### Claim 16 (depends on 13)

The pressure sensing method of claim 13, wherein the piezoelectric gate insulating layer comprises an organic matrix, in which piezoelectric inorganic nano-particles are dispersed, wherein the organic matrix comprises a piezoelectric organic material.

### Claim 17 (depends on 16)

The pressure sensing method of claim 16, wherein the piezoelectric organic material is selected from P(VDF-TrFE), P(VDF-TrFE-CFE), and P(VDF-TrFE-CtFE).

### Claim 18 (depends on 16)

The pressure sensing method of claim 16, wherein the piezoelectric inorganic nano-particles are selected from the group consisting of gallium orthophosphate (GaPO4), langasite (La3Ga5SiO14), a quartz analogic crystal, barium titanate (BaTiO3), lead titanate (PbTiO3), lead zirconate titanate (Pb[ZrxTi1-x]O3 (0≦x≦1), potassium niobate (KNbO3), lithium niobate (LiNbO3), lithium tantalate (LiTaO3), sodium tungstate (Na2WO3), zinc oxide (Zn2O3), Ba2NaNb5O5, Pb2KNb5O15, sodium potassium niobate ((K,Na)NbO3), bismuth ferrite (BiFeO3), sodium niobate (NaNbO3), bismuth titanate (Bi4Ti3O12), and sodium bismuth titanate (Na0.5Bi0.5TiO3).

### Claim 19

A pressure sensor comprising:
a substrate comprised of a flexible material;
a sensor thin film transistor (TFT) disposed on the substrate and comprising a gate insulating layer, wherein the gate insulating layer comprises a combination of an organic material and an inorganic material; and
a pressure sensing unit configured to obtain a remnant polarization value based on a drain current detected by the sensor TFT, and to sense pressure based on the remnant polarization value,
wherein when an amplitude of an AC signal applied to a gate of the sensor TFT is VGamp, an amplitude of the drain current is IDamp, and an average drain current value is IDmean, the remnant polarization value is in proportion to a value of
V
G
amp
⁢
⁢
I
D
mean
I
D
amp
,
and the pressure sensing unit is configured to sense the pressure by using a variation in the remnant polarization value.