FLEXIBLE STRETCHABLE CAPACITIVE SENSOR

• US 20180113032A1
• Filed: 10/10/2017
• Published: 04/26/2018
• Est. Priority Date: 10/11/2016
• Status: Abandoned Application

• Current Assignee: North Carolina State University (University of North Carolina System)
• Original Assignee: North Carolina State University (University of North Carolina System)
• Inventors: Dickey, Michael D., Cooper, Christopher B., Khan, Mohammad Rashed
• Application Number:
  US15/729,151
• Publication Number:
  US 20180113032A1
• Time in Patent Office: Days
• CPC Class Codes: G01L 1/142 using capacitors
• CPC Class Codes: G01L 1/146 for measuring force distributions, e.g. using force arrays G01L1/148 takes precedence
• CPC Class Codes: G06F 2203/04102 Flexible digitiser, i.e. constructional details for allowing the whole digitising part of a device to be flexed or rolled like a sheet of paper
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes
• CPC Class Codes: H03K 17/962 Capacitive touch switches
• CPC Class Codes: H03K 2017/9602 characterised by the type or shape of the sensing electrodes

Abstract

A flexible stretchable sensor, methods of use, and methods of forming the same are disclosed herein. In one implementation, the flexible stretchable sensor comprises a plurality of flexible and stretchable fibers in close proximity to one another, wherein each of the flexible fibers comprises a hollow electrically insulating elastomeric fiber at least partially filled with a flexible and stretchable conductive material and an electrical connector in electrical communication with the flexible and stretchable conductive material, wherein a change in an electrical parameter of at least one of the plurality of flexible and stretchable fibers is used to sense an event associated with the at least one of the plurality of flexible and stretchable fibers.

Claims

1. A flexible stretchable sensor comprising:

a plurality of flexible and stretchable fibers in close proximity to one another, wherein each of the flexible fibers comprises a hollow electrically insulating elastomeric fiber at least partially filled with a flexible and stretchable conductive material and an electrical connector in electrical communication with the flexible and stretchable conductive material,

wherein a change in an electrical parameter of at least one of the plurality of flexible and stretchable fibers is used to sense an event associated with the at least one of the plurality of flexible and stretchable fibers.

2. The flexible stretchable sensor of claim 1, wherein the plurality of flexible and stretchable fibers in close proximity to one another comprises at least two flexible and stretchable fibers twisted together.

3. The flexible stretchable sensor of claim 1, wherein the change in the electrical parameter of the at least one of the plurality of flexible and stretchable fibers comprises a change in capacitance of the at least one of the plurality of flexible and stretchable fibers is used to sense a change in torsion or a change in strain of the at least one of the plurality of flexible and stretchable fibers or the change in capacitance of the at least one of the plurality of flexible and stretchable fibers is used to sense a touch to the at least one of the plurality of flexible and stretchable fibers.

4. The flexible stretchable sensor of claim 3, wherein the change in capacitance of the at least one of the plurality of flexible and stretchable fibers used to sense the change in torsion or the change in strain is caused by a change in a geometry of the at least one of the plurality of flexible and stretchable fibers.

5. The flexible stretchable sensor of any of claim 3, wherein the change in capacitance of the at least one of the plurality of flexible and stretchable fibers used to sense the touch to the at least one of the plurality of flexible and stretchable fiber is caused by the touch.

6. The flexible stretchable sensor of claim 3, wherein torsion can be measured up to 10,800 rad/m or greater.

7. The flexible stretchable sensor of claim 3, wherein strain can be measured at 100 percent or greater increase in length of the plurality of flexible and stretchable fibers in close proximity to one another.

8. The flexible stretchable sensor of claim 1, wherein the plurality of flexible and stretchable fibers in close proximity to one another have a length, said length divided into a plurality of sections, wherein a change in capacitance in one or more of the plurality of flexible and stretchable fibers in close proximity to one another can be used to sense a touch to one or more of the plurality of flexible and stretchable fibers in close proximity to one another and to determine a specific section of the plurality of sections where the touch occurred.

9. The flexible stretchable sensor of claim 2, wherein the at least two flexible and stretchable fibers twisted together have a length, said length divided into at least two sections, wherein a first of the at least two flexible and stretchable fibers twisted together has the flexible and stretchable conductive material in a first and a second section of the at least two sections and a second of the at least two flexible and stretchable fibers twisted together has the flexible and stretchable conductive material in only a first section of the at least two sections and wherein a touch can be sensed and determined to be in the first section by a change in capacitance of the first and the second of the at least two flexible and stretchable fibers twisted together and a touch can be detected and determined to be in the second section by a change in capacitance of the first of the at least two flexible and stretchable fibers twisted together.

10. The flexible stretchable sensor of claim 1, wherein the plurality of flexible and stretchable fibers in close proximity to one another comprise at least three flexible and stretchable fibers twisted together and having a length, said length divided into at least three sections, wherein a first of the at least two flexible and stretchable fibers twisted together has the flexible and stretchable conductive material in a first, a second, and a third section of the at least three sections and a second of the at least three flexible and stretchable fibers twisted together has the flexible and stretchable conductive material in only the first section and the second section of the at least three sections and a third of the at least three flexible and stretchable fibers twisted together has the flexible and stretchable conductive material in only the first section of the at least three sections, wherein a touch can be sensed and determined to be in the first section by a change in capacitance of the first, the second and the third of the at least three flexible and stretchable fibers twisted together and a touch can be detected and determined to be in the second section by a change in capacitance of only the first and the second of the at least three flexible and stretchable fibers twisted together and a touch can be detected and determined to be in the third section by a change in capacitance of only the first of the at least three flexible and stretchable fibers twisted together.

11. The flexible stretchable electrical sensor of claim 1, wherein the plurality of flexible and stretchable fibers each have a triangular cross-section.

12. The flexible stretchable electrical sensor of claim 11, wherein the hollow electrically insulating elastomeric fiber has a wall thickness of approximately 55 μ

m to approximately 160 μ

m and the triangular cross-section has a side length of approximately 235 μ

m to approximately 850 μ

m.

13. A flexible stretchable sensor comprising:

at least two flexible and stretchable fibers having a length, said fibers helically twisted together substantially throughout the length, wherein each of the flexible fibers comprises;

a hollow electrically insulating elastomeric fiber at least partially filled with a flexible and stretchable conductive material; and

an electrical connector in electrical communication with the flexible and stretchable conductive material,

wherein a change in capacitance can be measured at the electrical connector of each of the at least two flexible and stretchable fibers, said change in capacitance caused by a change in strain or torsion to at least a portion of the length of the at least two flexible and stretchable fibers.

14. The flexible stretchable sensor of claim 13, wherein the change in capacitance of the at least two flexible and stretchable fibers caused by the change in the strain or torsion to the portion of the length of the at least two flexible and stretchable fibers is caused by a change in a geometry of the at least two flexible and stretchable fibers.

15. The flexible stretchable sensor of claim 14, wherein the change in a geometry of the at least two flexible and stretchable fibers comprises increasing a contact area between the two flexible and stretchable fibers, resulting in increased capacitance.

16. The flexible stretchable sensor of claim 13, wherein strain can be measured up to a 100 percent increase in the length of the at least two flexible and stretchable fibers.

19. The flexible stretchable sensor of claim 13, wherein torsion can be measured up to 10,800 rad/m or greater.

17. (canceled)

18. (canceled)

20. A flexible stretchable touch sensor comprising:

at least two flexible and stretchable fibers having a length helically twisted together substantially throughout the length, wherein each of the flexible fibers comprises;

a hollow electrically insulating elastomeric fiber at least partially filled with a flexible and stretchable conductive material; and

an electrical connector in electrical communication with the flexible and stretchable conductive material,

wherein said length is divided into at least two sections, wherein a first of the at least two flexible and stretchable fibers twisted together has the flexible and stretchable conductive material in a first and a second section of the at least two sections and a second of the at least two flexible and stretchable fibers twisted together has the flexible and stretchable conductive material in only a first section of the at least two sections and wherein a touch can be sensed and determined to be in the first section by a change in capacitance of the first and the second of the at least two flexible and stretchable fibers twisted together as measured at the electrical connectors of the first and the second of the at least two flexible and stretchable fibers and a touch can be detected and determined to be in the second section by a change in capacitance of the first of the at least two flexible and stretchable fibers twisted together as measured at the electrical connector of the first of the at least two flexible and stretchable fibers.

21. The flexible stretchable touch sensor of claim 20, wherein the change in capacitance of the at least two flexible and stretchable fibers used to sense the touch is caused by the touch.

22. A method of capacitive sensing, comprising:

providing a plurality of flexible and stretchable fibers in close proximity to one another, said plurality of flexible and stretchable fibers having a length, wherein each of the flexible fibers comprises a hollow electrically insulating elastomeric fiber at least partially filled with a flexible and stretchable conductive material and an electrical connector in electrical communication with the flexible and stretchable conductive material; and

sensing a change in capacitance of at least one of the plurality of flexible and stretchable fibers in close proximity to one another, wherein the change in capacitance is cause by at least one of a change in torsion to at least a portion of the length of the at least one of the plurality of flexible and stretchable fibers, a change in strain to at least a portion of the length of the at least one of the plurality of flexible and stretchable fibers, or at touch to at least one of the plurality of flexible and stretchable fibers.

23. A method of sensing using a flexible stretchable strain sensor, comprising:

providing at least two flexible and stretchable fibers having a length;

helically twisting the at least two flexible and stretchable fibers together substantially throughout the length, wherein each of the flexible fibers comprises a hollow electrically insulating elastomeric fiber at least partially filled with a flexible and stretchable conductive material, and an electrical connector in electrical communication with the flexible and stretchable conductive material; and

detecting, at the electrical connectors of each of the at least two flexible and stretchable fibers, a change in capacitance caused by a change in strain or torsion to at least a portion of the length of the at least two flexible and stretchable fibers.

24. The method of claim 23, wherein the change in capacitance of the at least two flexible and stretchable fibers caused by the change in the strain or torsion to the portion of the length of the at least two flexible and stretchable fibers is caused by a change in a geometry of the at least two flexible and stretchable fibers.

25. The method of claim 24, wherein the change in a geometry of the at least two flexible and stretchable fibers comprises increasing a contact area between the two flexible and stretchable fibers, resulting in increased capacitance.

26. The method of claim 23, wherein strain can be measured up to a 100 percent increase in the length of the at least two flexible and stretchable fibers.

29. The method of claim 23, wherein torsion can be measured up to 10,800 rad/m or greater.

27. (canceled)

28. (canceled)

30. A method of sensing touch using a flexible stretchable touch sensor, comprising:

providing at least two flexible and stretchable fibers having a length in close proximity substantially throughout the length, wherein each of the flexible fibers comprises a hollow electrically insulating elastomeric fiber at least partially filled with a flexible and stretchable conductive material, and an electrical connector in electrical communication with the flexible and stretchable conductive material;

dividing said length into at least two sections, wherein a first of the at least two flexible and stretchable fibers has the flexible and stretchable conductive material in a first and a second section of the at least two sections and a second of the at least two flexible and stretchable fibers has the flexible and stretchable conductive material in only a first section of the at least two sections; and

sensing a touch and determining the touch is in the first section by measuring a change in capacitance of both the first and the second of the at least two flexible and stretchable fibers;

or

sensing the touch and determining the touch is in the second section by measuring a change in capacitance of only the first of the at least two flexible and stretchable fibers.

31. (canceled)

32. (canceled)

33. (canceled)

34. (canceled)

35. (canceled)

36. (canceled)

37. (canceled)

38. (canceled)

39. (canceled)