Printed stretchable strain sensor

Patent metadata

Field	Value
Publication number	US-2016290880-A1
Application number	US-201415036937-A
Country	US
Kind code	A1
Filing date	Nov 17, 2014
Priority date	Nov 18, 2013
Publication date	Oct 6, 2016
Grant date	—

Abstract

A printed stretchable strain sensor comprises a seamless elastomeric body and a strain-sensitive conductive structure embedded in the seamless elastomeric body. The strain-sensitive conductive structure comprises one or more conductive filaments arranged in a continuous pattern. A method of printing a stretchable strain sensor comprises depositing one or more conductive filaments in a predetermined continuous pattern into or onto a support matrix. After the depositing, the support matrix is cured to embed a strain-sensitive conductive structure in a seamless elastomeric body.

First claim

1 . A printed stretchable strain sensor comprising:
a seamless elastomeric body; and a strain-sensitive conductive structure embedded in the seamless elastomeric body, the strain-sensitive conductive structure comprising one or more conductive filaments arranged in a continuous pattern.

2 . The printed stretchable strain sensor of claim 1 , wherein the strain-sensitive conductive structure comprises a substantially circular transverse cross-section.

3 - 4 . (canceled)

5 . The printed stretchable strain sensor of claim 1 , wherein the conductive filament is viscoelastic.

6 . The printed stretchable strain sensor of claim 5 , wherein the conductive filament comprises a shear-thinning material selected from the group consisting of: silicone oil, mineral oil, an organic solvent, an ionic liquid, a hydrogel, an organogel, and a liquid metal.

7 - 11 . (canceled)

12 . The printed stretchable strain sensor of claim 1 , comprising a sensitivity to strains as low as 1%.

13 . The printed stretchable strain sensor of claim 1 comprising a mechanical integrity sufficient to withstand cyclic loading from 0% to 100% strain at a strain rate of 10 mm/s or higher for at least 7000 cycles without failure.

14 - 15 . (canceled)

16 . A method of printing a stretchable strain sensor, the method comprising:
depositing one or more conductive filaments in a predetermined continuous pattern into or onto a support matrix; and after the depositing, curing the support matrix to embed a strain-sensitive conductive structure in a seamless elastomeric body.

17 . The method of claim 16 , wherein the support matrix is viscoelastic.

18 . The method of claim 16 , wherein the support matrix comprises a fluid filler layer thereon, and wherein curing the support matrix further comprises curing the fluid filler layer.

19 . The method of claim 16 , wherein a plateau value of shear elastic modulus G′ f of the conductive filament is from about 10 times to about 1000 times a plateau value of shear elastic modulus G′ s of the support matrix.

20 . The method of claim 18 , wherein the fluid filler layer comprises a strain-rate independent viscosity of no more than about 100 Pa·s.

21 - 22 . (canceled)

23 . The method of claim 16 , wherein
a plurality of the strain-sensitive conductive structures are embedded in the seamless elastomeric body.

24 . A method of printing a stretchable strain sensor, the method comprising:
depositing one or more sacrificial filaments comprising a fugitive ink in a predetermined continuous pattern into or onto a support matrix; after the depositing, curing the support matrix to form a seamless elastomeric body, removing the fugitive ink to create a continuous channel in the seamless elastomeric body; and flowing a conductive fluid into the continuous channel, thereby embedding a strain-sensitive conductive structure in the seamless elastomeric body.

25 . The method of claim 24 , wherein the fugitive ink is removed after curing the support matrix, upon cooling of the seamless elastomeric body.

26 . The method of claim 24 , wherein the conductive fluid is selected from the group consisting of: eutectic gallium-indium alloys, mercury, dispersions of metal particles, ionic fluids, intrinsically conductive polymers and hydrogels, and polymer and hydrogel composites.

27 . (canceled)

28 . The method of claim 24 , wherein the one or more sacrificial filaments are deposited at a printing speed of from about 0.1 mm/s to about 100 mm/s.

29 . The method of claim 24 , wherein the curing comprises applying UV light, heat, or a chemical curing agent.

30 . The method of claim 24 , wherein the support matrix comprises a fluid filler layer thereon, and wherein curing the support matrix further comprises curing the fluid filler layer.

31 . The method of claim 24 , wherein a plateau value of shear elastic modulus G′ f of the sacrificial filament is from about 10 times to about 1000 times a plateau value of shear elastic modulus G′ s of the support matrix.

32 . (canceled)

33 . The method of claim 24 , wherein a plurality of the strain-sensitive conductive structures are embedded in the seamless elastomeric body.

Assignees

• Harvard College

Inventors

• Lewis Jennifer A
• Muth Joseph T
• Vogt Daniel M
• Truby Ryan L
• Menguc Yigit
• Kolesky David B
• Wood Robert J

Classifications

• G01L1/2287 Primary

  constructional details of the strain gauges (adjustable resistors H01C10/00) · CPC title

• G01L1/18

  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 title

• G01L1/20

  by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids (of piezo-resistive materials G01L1/18); by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress · CPC title

• G06F3/014

  Hand-worn input/output arrangements, e.g. data gloves · CPC title