Flexible sensor and application thereof

• US 10,842,397 B2
• Filed: 12/06/2017
• Issued: 11/24/2020
• Est. Priority Date: 10/09/2016
• Status: Active Grant

• Current Assignee: Shenzhen Ruihu Technology Co., Ltd.
• Original Assignee: Shenzhen Ruihu Technology Co., Ltd.
• Inventors: Liu, Jianhui
• Primary Examiner(s): Noori, Max H
• Application Number:
  US16/340,494
• Publication Number:
  US 20200046236A1
• Time in Patent Office: 1,084 Days
• Field of Search: 73862625
• CPC Class Codes: A61B 2562/12 Manufacturing methods specially adapted for producing sensors for in-vivo measurements
• CPC Class Codes: A61B 5/02444 Details of sensor A61B5/02427 takes precedence
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: G01B 7/20 formed by printed-circuit technique
• CPC Class Codes: G01L 1/18 using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material
• CPC Class Codes: G01L 1/205 using distributed sensing elements
• CPC Class Codes: G01L 1/225 Measuring circuits therefor
• CPC Class Codes: H05K 1/028 Bending or folding regions of flexible printed circuits H05K1/0283 takes precedence
• CPC Class Codes: H05K 1/0393 Flexible materials H05K1/038 takes precedence; specific organic compositions are classified in H05K1/0313 and subgroups
• CPC Class Codes: H05K 1/167 incorporating printed resistors
• CPC Class Codes: H05K 2201/0133 Elastomeric or compliant polymer elastomeric conductor H05K2201/0314
• CPC Class Codes: H05K 2201/026 Nanotubes or nanowires
• CPC Class Codes: H05K 2201/0323 Carbon
• CPC Class Codes: H05K 2201/10151 Sensor

Abstract

A flexible sensor used for touch detection and an application thereof. The flexible sensor having a flexible substrate, at least two conductive layers and a plurality of electrodes, the conductive layers respectively covering two surfaces of the flexible substrate, the electrodes being arranged at two ends of the conductive layers, the conductive layers having a matrix and first conductive particles dispersed within the matrix. The sensor has stable output characteristics and good consistency between individuals, is easy to install, low-cost and highly sensitive, and can replace PVDF piezoelectric thin film sensors for monitoring human heartbeat and breathing state data.

Claims

1. A flexible sensor for sensing a strain, comprising a flexible substrate, electrically conductive layers disposed on a first surface and a second surface of the flexible substrate, and electrodes disposed at end portions of the electrically conductive layers, wherein

the electrically conductive layers include a matrix and electrically conductive particles dispersed in the matrix;

the electrically conductive particles include first electrically conductive particles and second electrically conductive particles, wherein the first electrically conductive particles include carbon powder or metal powder;

the second electrically conductive particles include carbon fibers, nanometer carbon tubes or graphene; and

two ends the second electrically conductive particles face electrodes of a same direction, respectively; and

the flexible substrate includes a first flexible substrate and a second flexible substrate which are vertically folded, the first electrically conductive layer and the second electrically conductive layer cover an upper surface of the first substrate, and a third electrically conductive layer and a fourth electrically conductive layer cover a lower surface of the second substrate.

2. The flexible sensor according to claim 1, wherein:

the matrix is a polymer.

3. The flexible sensor according to claim 2, wherein:

the polymer is selected from the group consisting of epoxy resin, polyurethane or acrylic resin.

4. The flexible sensor according to claim 1, further comprising elastic layers, the elastic layers covering outer surfaces of the electrically conductive layers.

5. The flexible sensor according to claim 4, wherein the elastic layers are rubber layers.

6. The flexible sensor according to claim 1, wherein the flexible sensor is applied to sense heartbeat or breathing of a human body.

7. The flexible sensor according to claim 1, wherein the first electrically conductive layer is disposed over the second electrically conductive layer, and the third electrically conductive layer is disposed over the fourth electrically conductive layer, wherein the first electrically conductive layer is electrically connected to the fourth electrically conductive layer, and the second electrically conductive layer is electrically connected to the third electrically conductive layer.

8. The flexible sensor according to claim 1, further comprising leads, the leads covering a first surface and a second surface of the flexible substrate.

9. The flexible sensor according to claim 1, wherein the first flexible substrate and the second flexible substrate are integrally bonded after folding a same block of material.

10. The flexible sensor according to claim 1, wherein the electrically conductive layers form a Wheatstone bridge.

11. The flexible sensor according to claim 10, wherein a bridge resistor of the Wheatstone bridge includes an SMD resistor disposed on a PCB substrate.

12. The flexible sensor according to claim 10, further comprising a signal amplifying circuit.

13. The flexible sensor according to claim 11, wherein the signal amplifying circuit comprises a differential capacitor, a negative feedback amplifying circuit, and a low-pass filter circuit.