Three-dimensional shape changing nanofiber electrodes

Abstract

A nanofiber electrode may be provided. The nanofiber electrode may include a first nanofiber layer and a second nanofiber layer. The nanofiber electrode may further include one or more conductive feedlines sandwiched in between the first nanofiber layer and the second nanofiber layer. At least of the first nanofiber layer or the second nanofiber layer, when exposed to a liquid, may be configured to absorb the liquid and expand thereby changing a three-dimensional shape of the nanofiber electrode.

Description

THREE-DIMENSIONAL SHAPE CHANGING NANOFIBER ELECTRODESCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application No. 63 / 351,738, filed June 13, 2022, which is hereby incorporated in its entirety by reference.FIELD OF DISCLOSURE

[0002] This disclosure is related nanofiber electrodes that may change their three-dimensional shapes, for example, to conform to a contour of a biological tissue.BACKGROUND

[0003] Electrodes are used medically to measure electrical parameters of and / or provide electrical stimulation to tissues. Medical usage of electrodes, however, provides a plethora of challenges. Tissues come in different shapes and sizes — and generally do not have smooth contours. Furthermore, tissues do not provide a latching structure or any other type of attachment for the electrodes. Additionally, electrodes have to be biocompatible not to have an adverse effect on the tissue and the homeostasis of the human body in general. The electrodes also should have sufficient insulation and robustness to withstand the impact of liquids surrounding the tissue.SUMMARY

[0004] In some embodiments, a nanofiber electrode may be provided. The nanofiber electrode may include a first nanofiber layer and a second nanofiber layer. The nanofiber electrode may further include one or more conductive feedlines positioned in between the first nanofiber layer and the second nanofiber layer. At least of the first nanofiber layer or the second nanofiber layer, when exposed to a liquid, may be configured to absorb the liquid and expand thereby changing a three-dimensional shape of the nanofiber electrode.

[0005] In some embodiments, a method of fabricating a nanofiber electrode may be provided. The method may include forming one or more conductive feedlines, using a patterned film, on a first nanofiber layer, the patterned film defining a shape of the one or more conductive feedlines and covering at least a portion of the one or more conductive feedlines with a second nanofiber layer such that at least the portion of the one or more conductive feedlines is positioned between the first nanofiber layer and the second nanofiber layer. At least one of the first nanofiber layer or the second nanofiber layer, when exposed to a liquid, may be configured to absorb the liquid and expand thereby changing a three- dimensional shape of the nanofiber electrode.

[0006] In some embodiments, a method of using a nanofiber electrode may be provided. The method may include deploying a nanofiber electrode to a tissue, the nanofiber electrode having a firstnanofiber layer, a second nanofiber layer, and one or more conductive feedlines positioned in between the first nanofiber layer and the second nanofiber layer. The method may also include exposing the nanofiber electrode to a biological liquid near the tissue causing at least one of the first nanofiber layer or the second nanofiber layer to absorb the biological liquid and expand thereby changing a three- dimensional shape of the nanofiber electrode, the changed three-dimensional shape conforming with a contour of the tissue.BRIEF DESCRIPTION OF DRAWINGS

[0007] FIG. 1 shows an illustrative biological environment, according to example embodiments of this disclosure.

[0008] FIG. 2A shows an illustrative method of fabricating a nanofiber electrode, according to example embodiments of this disclosure.

[0009] FIG. 2B shows a progress of fabrication through the discussed steps of the method of FIG. 2A, according to example embodiments of this disclosure.

[0010] FIG. 3A shows an illustrative method of generating a nanofiber layer to be used in a nanofiber electrode, according to example embodiments of this disclosure.

[0011] FIG. 3B shows the progress of generating the nanofiber layer through the discussed steps of the method of FIG. 3A, according to example embodiments of this disclosure.

[0012] FIG. 4 shows shape changing properties of the nanofiber layer generated by using the method shown in FIGS. 3A-3B, according to example embodiments of this disclosure.

[0013] FIG. 5A shows an illustrative method of generating a nanofiber substrate from biomass materials, according to example embodiments of this disclosure.

[0014] FIG. 5B shows the progress of generating the nanofiber substrate in a factory setting using the discussed steps of the method of FIG. 5 A.

[0015] FIG. 6 shows an illustrative biomass material for constructing a nanofiber substrate for a nanofiber electrode, according to example embodiments of this disclosure.

[0016] FIG. 7 shows an illustrative transition between wet and dry carbon nanotube electrodes, according to example embodiments of this disclosure.

[0017] FIG. 8 shows another illustrative transition between wet and dry silver nanowire electrodes, according to example embodiments of this disclosure.

[0018] FIG. 9 shows an illustrative method of using a nanofiber electrode, according to example embodiments of this disclosure.

[0019] The figures are for purposes of illustrating example embodiments, but it is understood that the present disclosure is not limited to the arrangements and instrumentality shown in the drawings. In the figures, identical reference numbers identify at least generally similar elements.DESCRIPTION

[0020] Embodiments disclosed herein are generally directed to nanofiber electrodes that may change their three-dimensional shapes to conform to the contours of biological tissues. For example, a substantially planar nanofiber electrode may be deployed to a biological tissue having a substantially circular contour, e.g., blood vessel, and the nanofiber electrode may change its substantially planar shape into a substantially circular three-dimensional shape. This three-dimensional shape change not only conforms to the contour of the biological tissue but may also provide an attachment between the biological tissue and the nanofiber electrode.

[0021] The three-dimensional shape change may be facilitated by nanofiber layers of the nanofiber electrode. One or more nanofiber layers may expand by absorbing biological liquid, e.g., blood, around the biological tissue. This expansion may cause the nanofiber electrode to bend, warp, or have any other three-dimensional shape change. Such expansion may not change electrical and chemical properties of the nanofiber layers, the expansion does not affect the electrical measurements and stimulations performed by the nanofiber electrode, and also does not affect the insulation provided by the nanofiber layers to conductive feedlines. The expansion of the one or more nanofiber layers, and therefore the change in three-dimensional shape of the nanofiber electrode, may further be facilitated by a polymer layer. A patterned polymer layer may be attached to one or more of the nanofiber layers, and the polymer layer too may absorb the biological liquid to further enhance the change in the three- dimensional shape. As with the nanofiber layers, the electrical and chemical properties of the patterned polymer may not change due to the absorption of the biological liquid. Therefore, the nanofiber electrode may be robust against the biological environment when deployed.

[0022] The nanofiber layers may be made of biomass materials that is biocompatible and biodegradable. In some examples, the biomass materials such as chitin may aid the healing of the tissue around the nanofiber electrode. Additionally, carbon nanotubes or silver nanowires that are used to construct the feedlines may not have adverse biological effects. Furthermore, the patterned polymer may also not have adverse biological effects. Therefore, the embodiments disclosed herein may provide a significant improvement over the conventional electrodes.

[0023] FIG. 1 shows an illustrative biological environment 100, according to example embodiments of this disclosure. In some embodiments, the illustrative biological environment 100 may be representative of a human body environment and / or any other type of biological medium (e.g., animal body, tissue culture, etc.). Biological environment 100 may include a nanofiber electrode 102 deployed on a tissue 104. As shown, the nanofiber electrode 102 may conform to the shape / contour of the tissue 104. In some embodiments, tissue 104 may be representative of a human tissue or animal tissue (e.g., a nerve fiber, a muscle fiber, etc.).

[0024] The nanofiber electrode 102 may include a plurality of electrical contacts 106a-106i and a corresponding plurality of feedlines 108a- 108i. The plurality of electrical contacts 106a-106i may be configured to measure electrical parameters of the tissue 104. The plurality of feedlines 108a- 108i may be configured to transmit the measured electrical parameters to connected electronics (not shown). In some embodiments, the plurality of feedlines 108a-108i may be configured to transmit electrical stimulation to the corresponding plurality of electrical contacts 106a-106i, which may then apply the electrical stimulation to the tissue 104.

[0025] The electrical contacts 106a-106i may be exposed to contact the tissue 104, but the feedlines 108a-108i may be insulated from the environment with layers of nanofibers. For example, the feedlines 108a-108i may be positioned between two layers of insulative nanofibers.

[0026] In some embodiments, the nanofiber layers of the nanofiber electrode 102 may be configured to change their shapes when exposed to a liquid medium (e.g., biological liquid medium such as blood). This change in shape may allow the nanofiber electrode 102 to conform to the contours of tissue 104. For example, as shown tissue 104 is cylindrical in shape, having a circular cross-section. In such example, nanofiber electrode 102 may wrap around tissue 104. The one or more nanofiber layers of the nanofiber electrode 102 may absorb the liquid without degradation and without changes in electrical and chemical properties. Therefore, when the nanofiber electrode 102 physically changes its shapes to conform to the contour of the tissue 104, the feedlines 108a-108i remain insulated and the electrical measurement and the electrical stimulation functionality is not affected.

[0027] In some embodiments, in addition to the nanofiber layers, the nanofiber electrode 102 may include a polymer layer (described in detail in reference to FIGS. 3A-3B below). The polymer layer may also absorb the liquid and cause a further change in shape of the nanofiber electrode 102. Therefore, a combination of the nanofiber layers and the polymer layers may provide a desired level of flexibility for the nanofiber electrode 102, which may change to a desired shape to conform to a contour of the biological tissue during deployment.

[0028] In addition to conforming to the contour of the tissue 104, the nanofiber electrode 102 may itself form an attachment to the tissue. As the nanofiber electrode 102 may wrap around the tissue 104, the wrapping around may function as a mechanical, non-penetrative anchor between the tissue 104 and the nanofiber electrode 102. Therefore, additional anchoring parts may not be required when the nanofiber electrode 102 is deployed to the tissue 104.

[0029] FIG. 2A shows an illustrative method 200 of fabricating a nanofiber electrode, according to example embodiments of this disclosure. FIG. 2B shows a progress of fabrication through the discussed steps of the method 200, according to example embodiments of this disclosure.

[0030] The method may begin at step 202. At step 202, a nanofiber substrate 224 and a polyimide film 222 (just an example, and other types of materials may be used as well) are prepared. In some embodiments, nanofiber substrate 224 may be representative of a nanofiber paper substrate. Insome embodiments, the polyimide film 222 may include a pattern formed therein. In some embodiments, the pattern may be formed from by laser cutting a desired pattern into a blank polyimide film. The pattern formed in polyimide film 222 may define the structure of the feedlines in the fabricated nanofiber electrode. That is, the pattern may form openings for a conductive material 226 (as described below) to spread on the nanofiber substrate to a shape and size defined by the pattern.

[0031] At step 204, feedlines may be formed. In some embodiments, the feedlines may be formed using substeps 205, 206, 208. At substep 205, a conductive material 226 may be deposited on the combination of the polyimide film 222 and nanofiber substrate 224. As indicated above, polyimide film 222 includes a pattern formed therein. When deposited, the conductive material 226 may form the feedlines in the openings of the patterned polyimide film 222. In some embodiment, to achieve such functionality, the conductive material 226 may have a desired viscosity to be able to spread on the nanofiber substrate 224 within the laser cut structure of the patterned polyimide film 222. In some embodiments, the conductive material 226 may include a nanowires suspension. In some embodiments, the conductive material 226 may include a carbon nanotubes suspension.

[0032] At substep 206, the conductive material 226 may be spread within the laser cut patterns of the patterned polyimide film 222 and on the nanofiber substrate 224. In some embodiments, the spreading may include a filtration process, where the nanowires suspension or the carbon nanotubes suspension, e.g., a solution containing the solute (nanowires, carbon nanotubes), may act as a solvent and the nanofiber substrate 224 may act as a membrane for the solute to spread on the membrane. In some embodiments, the conductive material 226 may be spread mechanically, e.g., by using a spreading arm.

[0033] At substep 208, the patterned polyimide film 222 may be peeled off from the nanofiber substrate 224. In some embodiments, the patterned poly imide film 222 is peeled off when the conductive material 226 and the nanofiber substrate 224 have dried. That is, the patterned polyimide film 222, which provided the structure for the conductive material 226 to spread, may no longer be needed after the conductive material 226 may have spread and dried to a desired shape and size.

[0034] At step 210, a mask 228 may be applied at the ends the conductive material 226. The mask 228 may form a barrier layer on top of the corresponding end portions of the conductive material 226 when non-conductive nanofibers (e.g., as passivation layer) may be deposited. In some embodiments, mask 228 may be formed from Polydimethylsiloxane (PDMS).

[0035] At step 212, nanofibers 227 may be deposited on the conductive material 226. The nanofibers 227 may form a passivation (e.g., for non-conductive protection) layer on top of the conductive material 226. In some embodiments, nanofibers 227 may have similar physical and / or chemical properties to the nanofiber substrate 224. In some embodiments, the nanofibers 227 and the nanofiber substrate 224 may have different physical and / or chemical properties.

[0036] At step 214, the nanofibers 227 may be spread on the conductive material 226. In some embodiments, the nanofibers 227 may be in a suspension and the spreading may be through filtration. During filtration, the nanofibers 227 may act as a solute and the conductive material 226 may act as membrane for the spread of the solute. The masked portions of the conductive material 226, however, may not be reached by the spreading the nanofibers 227. In some embodiments, the nanofibers 227 may be spread mechanically, e.g., by using a spreading arm. After the spreading of the nanofibers 227, the conductive material 226, except for the masked portions, is positioned in between two layers of nanofibers: the nanofiber substrate 224 and the layer form by the nanofibers 227. Each of the nanofiber substrate 224 and the nanofibers 227 may change its shape when exposed to a liquid medium.

[0037] At step 216, the mask 228 (e.g., PDMS mask) may be removed to expose the electrical contacts 230.

[0038] At step 218, the nanofiber substrate 224 and the nanofibers 227 may be cut into a desired shape to form a nanofiber electrode 232 with two feedlines 234a, 234b formed by the conductive material 226. A portion of the conductive material 226 is exposed forming electrical contacts 230 for the nanofiber electrode 232. The nanofiber electrode 232 may now be ready for deployment to a human tissue.

[0039] In some embodiments, the length of each of the feedlines 234a, 234b of the nanofiber electrode 232 filament may be approximately 1 mm, the distance between the feedlines 234a, 234b may be approximately 300 pm, and the width of the feedlines 234a, 234b at the thin end may be approximately 200 pm. The thickness of each of the top nanofiber layer and the bottom nanofiber layer (e.g., formed by nanofiber substrate 224) may be approximately 5 pm, while the thickness of each feedline 234a, 234b may be approximately 2.46 ± 0.135 pm.

[0040] FIG. 3A shows an illustrative method 300 of generating a nanofiber substrate, such as a nanofiber substrate 224, to be used in a nanofiber electrode, according to example embodiments of this disclosure. FIG. 3B shows the progress of generating the nanofiber substrate through the discussed steps of the method 300, according to example embodiments of this disclosure.

[0041] The method 300 may begin at step 302. At step 302, an acryl amide monomer 308 may be set on a nanofiber mat 310. The nanofiber mat 310 may be made biomass materials such as chitin, chitosan, etc. The assembly of the acryl amide monomer 308 and the nanofiber mat 310 may be performed on an inert, non-reactive substrate 312.

[0042] At step 304, the acryl amide monomer 308 may be polymerized. In some embodiments, the polymerization may be performed using an ultraviolet light. The polymerization may form a duallayer of the polyacrylamide 314 and the nanofiber mat 310.

[0043] At step 306, patterns may be generated on the dual-layered polyacrylamide 314 and the nanofiber mat 310 by using ablation. In some embodiments, the ablation may include laser ablation. It should be understood that the laser ablation may not change the insulative properties of the dual-layeredpolyacrylamide 314 and the nanofiber mat 310. That is, even though the pattern includes gaps, the duallayer can still receive and hold conductive material, and insulate the conductive material when the duallayer is exposed to a liquid medium.

[0044] FIG. 4 shows shape changing properties of the nanofiber layer generated by using the method 300 shown in FIGS. 3A-3B, according to example embodiments of this disclosure. As shown, the patterning may allow for the polyacrylamide 314 to swell in a liquid medium without causing damage to the structural integrity of the overall structure. For example, a planar polyacrylamide 314 and nanofiber mat 310 may form a planar structure 420 that may fold and form a cylindrical structure 422 (with a circular cross section) when exposed to the liquid medium. When dried, the dual-layer may revert back to the original planar structure 420. The change in the shape between the planar structure 420 and the circular structure 422 may be without chemical changes to the polyacrylamide 314 and the nanofiber mat 310. Therefore, the dual-layer structure may become a self-folding device, assuming a folded shape when inserted in a liquid medium and assuming / reverting back to a non-folded shape when not in a liquid medium. This self-folding property may allow a nanofiber electrode to conform to a contour of a biological tissue. The folded structure may further perform as a mechanical anchor between the nanofiber electrode and the biological tissue. For example, one or more nanofiber layers of the nanofiber electrode 102 shown in FIG. 1 may be formed using this dual layer structure.

[0045] FIG. 5A shows an illustrative method 500 of generating a nanofiber substrate (e.g., nanofiber substrate 224) from biomass materials, according to example embodiments of this disclosure. FIG. 5B shows the progress of generating the nanofiber substrate in a factory setting using the discussed steps of the method 500, according to example embodiments of this disclosure. As shown, the final constructed nanofiber substrate may be in a paper form.

[0046] The method 500 may begin at step 502, where raw biomass material 512, extracted from biological materials 510 such as cellulose, chitin, chitosan, and / or silk fibroin, may be fed into an extraction chamber and pressurized with one or more intensifiers. Particularly, there may be two intensifiers 514a and 514b that may generate two pressurized slurry streams (e.g., containing biomass slurry and water) of the biomass material 512. In some embodiments, one or more of the two intensifiers 514a and 514b may pressurize the slurry stream to a relatively high pressure of 245 MPa (mega Pascals).

[0047] At step 504, the two pressurized slurry streams may be collided. For example, a collider 518 may be used for the colliding the pressurized slurry streams at an oblique angle, and the pressurizing and colliding may generate nanofibers from the biomass material 512. In some embodiments, the pressurizing and colliding steps may be collectively referred to as water-jetting.

[0048] At step 506, the nanofibers may be discharged through a cooler 520. The cooler 520 may lower the high temperature generated during the pressurizing and colliding steps.

[0049] At step 508, the cooled nanofibers may be filtered through different membranes 522.After filtration, a nanofiber paper substrate 524 may be obtained. The nanofiber paper substrate 524may be used for fabricating a nanofiber electrode. For example, the nanofiber paper substrate 524 may be used as the nanofiber substrate 224 in method 200 and as a nanofiber mat 310 in method 300. The nanofiber paper substrate 524 may form an insulating part of nanofiber electrodes.

[0050] Nanofiber substrates of any kind of biomass material may be generated using the method 500. Some non-limiting examples may include cellulose based nanofiber substrate, chitosan based nanofiber substrate, chitin based nanofiber substrate, and silk fibroin based nanofiber substrate. In some embodiments, each of the nanofiber substrates may have thickness of approximately 5 pm. In some embodiments, the optical transparency of the nanofiber substrates may be as follows: the chitin based nanofiber substrate may be more transparent than the chitosan based nanofiber substrate; the chitosan based nanofiber substrate may be more transparent than chitin based nanofiber substrate; and the chitin based nanofiber substrate may be more transparent than the silk fibroin based nanofiber substrate.

[0051] FIG. 6 shows an illustrative biomass material for constructing a nanofiber substrate for a nanofiber electrode, according to example embodiments of this disclosure. The biomass material may be used, for example, by method 500 to generate the nanofiber paper substrate 524. As shown, a crab shell 602 may be used as a biomass material. The crab shell 602 may have hierarchically structured tissue 604 formed by chitin nanofibers and protein complex 606. Within the chitin nanofibers and protein complex 606, there may be multiple strands 608. A strand 608 may have multiple nanofibers 610. Therefore, nanofibers 610 may be extracted from the crab shell 602 through one or more processes 612 such as deproteinization, decalcification, delipidation, decolorization, and / or any other type of process. An example process of extracting the nanofibers 610 may be water-jetting — applying a high pressure water on the biomass.

[0052] FIG. 7 shows an illustrative transition between wet and dry carbon nanotube electrodes, according to example embodiments of this disclosure. For example, a dry electrode 702 and a wet electrodes 704 are shown. As can be seen, the shape of the dry electrode 702 has changed when it is put in a liquid medium (e.g., inside human body).

[0053] FIG. 8 shows another illustrative transition between wet and dry silver nanowire electrodes, according to example embodiments of this disclosure. For example, a dry electrode 802 and a wet electrode 804 are shown. As can be seen, the shape of the dry electrode 802 has changed when it is put in a liquid medium (e.g., inside human body).

[0054] FIG. 9 shows an illustrative method 900 of using a nanofiber electrode, according to example embodiments of this disclosure. The method 900 may be used for providing electrical stimulations to and / or for performing electrical measurements of a tissue.

[0055] At step 902 the nanofiber electrode may be deployed to the tissue. In some embodiments, the tissue may have a substantially circular contour. For example, blood vessels and nerves generally may be cylindrical with substantially circular cross-sections. As discussed throughout this disclosure,the nanofiber electrode may have a first nanofiber layer, a second nanofiber layer, and one or more conductive feedlines positioned in between the first nanofiber layer and the second nanofiber layer.

[0056] At step 904, the nanofiber electrode may be exposed to a biological liquid (e.g., blood) near the tissue causing the nanofiber electrode to change its three dimensional shape. The shape change may be cause by at least one of the first nanofiber layer or the second nanofiber layer to absorbing the biological liquid and then expanding.

[0057] Additional examples of the presently described method and device embodiments are suggested according to the structures and techniques described herein. Other non-limiting examples may be configured to operate separately or can be combined in any permutation or combination with any one or more of the other examples provided above or throughout the present disclosure.

[0058] It will be appreciated by those skilled in the art that the present disclosure can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restricted. The scope of the disclosure is indicated by the appended claims rather than the foregoing description and all changes that come within the meaning and range and equivalence thereof are intended to be embraced therein.

[0059] The method steps discussed herein are provided as just examples and should not be considered limiting. Methods with alternative, additional, or fewer number of steps are to be considered within the scope of this disclosure. Furthermore, the steps are numbered merely for identification and the numbering is meant neither to convey a limitation to the shown discrete steps nor a limitation to the shown sequence of the steps.

[0060] It should be noted that the terms “including” and “comprising” should be interpreted as meaning “including, but not limited to”. If not already set forth explicitly in the claims, the term “a” should be interpreted as “at least one” and “the”, “said”, etc. should be interpreted as “the at least one”, “said at least one”, etc. Furthermore, it is the Applicant's intent that only claims that include the express language "means for" or "step for" be interpreted under 35 U.S.C. 112(f). Claims that do not expressly include the phrase "means for" or "step for" are not to be interpreted under 35 U.S.C. 112(f).

Claims

CLAIMSWhat is claimed is:

1. A nanofiber electrode comprising: a first nanofiber layer; a second nanofiber layer; one or more conductive feedlines positioned in between the first nanofiber layer and the second nanofiber layer; and at least one of the first nanofiber layer or the second nanofiber layer, when exposed to a liquid, is configured to absorb the liquid and expand thereby changing a three-dimensional shape of the nanofiber electrode.

2. The nanofiber electrode of claim 1, wherein at least one of the first nanofiber layer or the second nanofiber layer is formed by a biomass material.

3. The nanofiber electrode of claim 2, wherein the biomass material comprises at least one of chitin, chitosan, or silk fibroin.

4. The nanofiber electrode of claim 1, wherein the one or more conductive feedlines are formed by carbon nanotubes.

5. The nanofiber electrode of claim 1, wherein the one or more conductive feedlines are formed by silver nanowires.

6. The nanofiber electrode of claim 1, wherein at least one of the first nanofiber layer and the second nanofiber layer comprises a polymer layer has a pattern configured to facilitate the changing of the three-dimensional shape of the nanofiber electrode.

7. The nanofiber electrode of claim 6, wherein the polymer layer is formed by polyacrylamide.

8. The nanofiber electrode of claim 1, wherein the nanofiber electrode is configured to be substantially in a planar shape when dry, and wherein at least a portion of the nanofiber electrode is configured to be substantially circular exposed to the liquid.

9. The nanofiber electrode of claim 1, further comprising: one or more electrical contact openings in the one or more conductive feedlines.

10. A method of fabricating a nanofiber electrode, the method comprising: forming one or more conductive feedlines, using a patterned film, on a first nanofiber layer, the patterned film defining a shape of the one or more conductive feedlines; and covering at least a portion of the one or more conductive feedlines with a second nanofiber layer such that at least the portion of the one or more conductive feedlines is positioned between the first nanofiber layer and the second nanofiber layer, wherein at least one of the first nanofiber layer or the second nanofiber layer, when exposed to a liquid, is configured to absorb the liquid and expand thereby changing a three-dimensional shape of the nanofiber electrode.

11. The method of claim 10, wherein at least one of the first nanofiber layer and the second nanofiber layer is formed by a biomass material.

12. The method of claim 11, wherein the biomass material comprises at least one of chitin, chitosan, or silk fibroin.

13. The method of claim 10, wherein the one or more conductive feedlines are formed by carbon nanotubes.

14. The method of claim 10, wherein the one or more conductive feedlines are formed by silver nanowires.

15. The method of claim 10, wherein at least one of the first nanofiber layer and the second nanofiber layer comprises a polymer layer has a pattern configured to facilitate the changing of the three- dimensional shape of the nanofiber electrode.

16. The method of claim 15, wherein the polymer layer is formed by polyacrylamide.

17. The method of claim 10, further comprising: forming one or more electrical contact openings in the one or more conductive feedlines.

18. A method of using a nanofiber electrode comprising:deploying a nanofiber electrode to a tissue, the nanofiber electrode having a first nanofiber layer, a second nanofiber layer, and one or more conductive feedlines positioned in between the first nanofiber layer and the second nanofiber layer; and exposing the nanofiber electrode to a biological liquid near the tissue causing at least one of the first nanofiber layer or the second nanofiber layer to absorb the biological liquid and expand thereby changing a three-dimensional shape of the nanofiber electrode, the changed three-dimensional shape conforming with a contour of the tissue.

19. The method of claim 18, wherein the contour of the tissue is substantially circular and the changed three-dimensional shape is substantially circular.

20. The method of claim 18, further comprising: providing electrical stimulations to or performing electrical measurements of the tissue using the one or more conductive feedlines.

Images