WO2023235860A1

WO2023235860A1 - Flexible electrodes formed by kirigami structures with silane protection

Info

Publication number: WO2023235860A1
Application number: PCT/US2023/067859
Authority: WO
Inventors: Peng Hu; Tetsuhiko Teshima; Bernhard Wolfrum
Original assignee: Ntt Research, Inc.
Priority date: 2022-06-03
Filing date: 2023-06-02
Publication date: 2023-12-07

Abstract

A flexible electrode is provided. The flexible electrode may include a bottom parylene layer etched with a first kirigami pattern; a top parylene layer etched with a second kirigami pattern, the first kirigami pattern and the second kirigami pattern forming a kirigami structure configured to allow a stretching of the flexible electrode in one or more of a horizontal direction and a vertical direction; and a silane layer in between the first kirigami pattern and the second kirigami pattern, the silane layer configured to protect the first kirigami pattern.

Description

FLEXIBLE ELECTRODES FORMED BY KIRIGAMI STRUCTURES WITH SILANE PROTECTION

CROSS REFERENCE TO RELATED APPLICATIONS

[1] This application claims priority to U.S. Provisional Application No. 63/348,794, filed June 3, 2022, which is hereby incorporated by reference in its entirety.

FIELD OF DISCOSURE

[2] This disclosure is generally directed to flexible electrodes having kirigami structures that allow the electrodes to stretch in multiple directions.

BACKGROUND

[3] Flexible electrodes are typically used for clinically measuring human body biophysical properties because, for example, they are able to more closely match the contour of the underlying organs compared to conventional non- flexible electrodes. The electrodes’ flexibility typically allows for the electrodes to be stretched, so that a dimension of the electrodes may be increased as desired.

SUMMARY

[4] In some embodiments, a flexible electrode is provided. The flexible electrode may include a bottom parylene layer etched with a first kirigami pattern; a top parylene layer etched with a second kirigami pattern, the first kirigami pattern and the second kirigami pattern forming a kirigami structure configured to allow a stretching of the flexible electrode in one or more of a horizontal direction and a vertical direction; and a silane layer in between the first kirigami pattern and the second kirigami pattern, the silane layer configured to protect the first kirigami pattern.

[5] In some embodiments, a method of manufacturing a flexible electrode is provided. The method may include coating a first parylene layer on a substrate; applying a first mask pattern on the first parylene layer; generating a first kirigami pattern by etching the first parylene layer through the first mask pattern; and coating the etched first parylene layer with a silane layer. The method may further include coating the silane layer with a second parylene layer; applying a second mask pattern on the second parylene layer; and generating a second kirigami pattern by etching the second parylene layer through the second mask pattern, the first kirigami pattern and the second kirigami pattern forming a kirigami structure configured to allow a stretching of a fabricated flexible electrode in one or more of a horizontal direction and a vertical direction.

[6] In some embodiments, a method of using a flexible electrode is provided. The method may include stretching the flexible electrode in one or more of a horizontal direction and a vertical direction to conform to a contour of a human organ, the flexible electrode formed by a bottom parylene layer etched with a first kirigami pattern, a top parylene layer etched with a second kirigami pattern, and a silane layer in between the first kirigami pattern and the second kirigami pattern, the first kirigami pattern and the second kirigami pattern forming a kirigami structure configured to allow the stretching. The method may also include adhering the stretched flexible electrode to the human organ.

BRIEF DESCRIPTION OF DRAWINGS

[7] FIG. 1A shows a flow diagram of a method of fabricating a flexible electrode with a kirigami structure, according to example embodiments of this disclosure.

[8] FIG. IB illustrates progress of flexible electrode structure fabrication associated with the steps discussed in FIG. 1A, according to example embodiments of this disclosure.

[9] FIG. 2A shows a top view of illustrative flexible electrodes with kirigami structures, according to example embodiments of this disclosure.

[10] FIG. 2B shows example dimensions of kirigami structures shown in FIG. 2A, according to example embodiments of this disclosure.

[11] FIG. 3A shows a flow diagram of the method of fabricating a flexible electrode with a kirigami structure and silane protection, according to example embodiments of this disclosure.

[12] FIG. 3B illustrates progress of flexible electrode fabrication associated with the steps discussed in FIG. 3A, according to example embodiments of this disclosure.

[13] FIG. 4A shows a flow diagram of fabricating a flexible electrode with a kirigami structure and silane protection, according to example embodiments of this disclosure.

[14] FIG. 4B illustrates progress of flexible electrode fabrication associated with the steps discussed in FIG. 4A, according to example embodiments of this disclosure.

[15] FIG. 5 A shows a flow diagram of a method of fabricating a flexible electrode with a kirigami structure and silane protection, according to example embodiments of this disclosure.

[16] FIG. 5B illustrates progress of flexible fabrication associated with the steps discussed in FIG. 5A, according to example embodiments of this disclosure.

[17] FIG 6A shows a process illustrating how silaning may protect underlying layers, according to example embodiments of this disclosure.

[18] FIG. 6B shows another process illustrating how silaning may protect underlying layers, according to example embodiments of this disclosure.

[19] FIG. 6C shows yet another process illustrating how silaning may protect underlying layers, according to example embodiments of this disclosure.

[20] FIG. 7A shows a flow diagram of the method of fabricating a kirigami structure, according to example embodiments of this disclosure.

[21] FIG. 7B illustrates progress of flexible electrode fabrication associated with the steps discussed in FIG. 7A, according to example embodiments of this disclosure. [22] FIG. 8 shows an illustrative process of demonstrating silane protection, according to example embodiments of this disclosure.

[23] FIG. 9 shows an illustrative flexible electrode having a kirigami structure, according to example embodiments of this disclosure.

[24] FIG. 10 shows a flow diagram of an illustrative method of using a flexible electrode, according to example embodiments of this disclosure.

[25] 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

[26] Embodiments disclosed generally relate to flexible electrodes and a method of fabricating the same. Conventionally, flexible electrodes have several technical shortcomings. One of the larger shortcomings is their inability to stretch along multiple dimensions. For example, conventional flexible electrodes are limited in that they can typically be stretched only in one dimension (e.g., horizontally, along a width of a sheet electrode). Such limitation may be attributed to the one -dimensional stretchability of the fabric or polymer material used in forming these electrodes. As a result of the limited ability to stretch across multiple dimensions, existing flexible electrodes are not amenable for use in wrapping around an organ or otherwise covering a three-dimensional surface because of their inability to match the contours of the three-dimensional surface.

[27] Additionally, conventional flexible electrodes also do not provide adequate protection for the underlying tissues and cells. For example, if a chemical is inadvertently spilled on the electrode, the chemical may disintegrate the structure of the electrode and move on to adversely affect the underlying tissues and cells.

[28] One or more techniques provided herein improve upon conventional flexible electrodes by providing an improved flexible electrode that is capable of achieving flexibility beyond a single direction by forming kirigami structures during the fabrication process. A kirigami structure may generally refer to a three-dimensional structure with extendable/deformable gaps in both vertical and horizontal directions. Unlike conventional flexible electrodes, the formation of a kirigami structure during the fabrication process may allow the present flexible electrode to be stretched beyond a single dimension (e.g., both horizontally along the width and/or the length, and vertically along the height, e.g., normal to electrode plane). For example, the one or more gaps in the kirigami structure may extend horizontally to allow for the horizontal flexibility, and one or more gaps in the kirigami structure may extend vertically to allow for the vertical flexibility. This multi-dimensional flexibility provided by the kirigami structures may allow the flexible electrodes to conform to contours of a three-dimensional object, such as, but not limited to, body organs (e.g., heart). [29] Additionally, to improve upon conventional electrodes’ inadequate protection of underlying tissues and cells, one or more techniques provided herein utilize a silane layer during the fabrication process. The silane layer may provide protection for the underlying layers (i.e., those layers below the silane layer) from chemical or radiative activity (e.g., chemical and/or radiative etching). When deployed on a bodily organ, the silane layer may also protect underlying tissue thereby making the flexible electrode safer to use compared to conventional electrodes.

[30] FIG. 1 A shows a flow diagram of a method 100 of fabricating a flexible electrode with a kirigami structure, according to example embodiments of this disclosure. FIG. IB illustrates progress of flexible electrode structure fabrication associated with the steps discussed in FIG. 1A, according to example embodiments of this disclosure.

[31] At step 104, a first layer of parylene coating may be applied on a substrate 120 (e.g., formed by glass) to form a parylene layer 122. The parylene layer 122 is just but an example and any form of polymer material forming a similar layer should be considered within the scope of this disclosure.

[32] At step 106, a first mask pattern 124 may be applied on the parylene layer 122. The first mask pattern 124 may form a gap within the parylene layer 122 during etching, wherein the gap may be a part of the kirigami structure.

[33] At step 108, a second layer of parylene coating may be applied. The second layer of parylene coating may be used to increase the height of the parylene layer 122. After the second layer of parylene coating, the parylene layer 122, with the increased height, may fully cover the first mask pattern 124.

[34] At step 110, an aluminum layer 126 may be formed on top of the parylene layer 122. In some embodiments, the aluminum layer 126 may be formed using an aluminum coating technique. The aluminum layer 126 may protect the covered portions of the parylene layer 122 during etching.

[35] At step 112, a second mask pattern 128 may be applied on top of the aluminum layer 126. The second mask pattern 128 may be used for aluminum etching of step 114. In other words, the second mask pattern 128 may define the gaps where the aluminum layer 126 may be etched.

[36] At step 114, the aluminum layer 126 may be etched at the portions not covered by the second mask pattern 128 to open portions of the parylene layer 122 for plasma etching. That is, the etched portions of the aluminum layer 126 may facilitate the plasma etching of the corresponding portions of the parylene layer 122 below, while the non-etched portions may cover and protect the corresponding portions (i.e., non-exposed portions) of the parylene layer 122.

[37] The subsequent steps 116a-118a and 116b-l 18b may be alternate steps, with the steps 116a-118a generating a flexible electrode with a first type of kirigami structure and the steps 116b- 118b generating a flexible electrode with a second type of kirigami structure.

[38] At step 116a, the parylene layer 122 may be etched to a first depth, e.g., up to the bottom portion of the first mask pattern 124. In some embodiments, the parylene layer 122 may be etched using plasma etching techniques, such as, but not limited to oxygen plasma etching. [39] At step 118a, the extraneous layers, e.g., second mask pattern 128, aluminum layer 126, first mask pattern 124, may be cleaned to form a flexible electrode having a first type of kirigami structure 134a. Within the kirigami structure 134a, there may be a top layer with a first kirigami pattern 136a (top kirigami pattern) and a bottom layer with a second kirigami pattern 138a (bottom kirigami pattern).

[40] Alternatively, at step 116b, the parylene layer 122 may be etched to a second depth, e.g., up to the top surface of the substrate. As described above, the parylene layer 122 may be etched using plasma etching techniques, such as, but not limited to oxygen plasma etching.

[41] At step 118b, the extraneous layers, e.g., second mask pattern 128, aluminum layer 126, first mask pattern 124, may be cleaned to form a flexible electrode having a second type of kirigami structure 134b. Within the kirigami structure 134b, there may be a top layer with a first kirigami pattern 136b (top kirigami pattern) and a bottom layer with a second kirigami pattern 138b (bottom kirigami pattern).

[42] The kirigami structures 134a, 134b may be formed within the parylene layer 122 by forming the different gaps within the parylene layer 122. The gaps may be formed through the use of masks, e.g., the first mask pattern 124 defining a horizontal gap in the parylene layer 122, and/or etching, e.g., the plasma etching defining the vertical gaps. Therefore, the kirigami structures 134a, 134b — with the specifically sculpted gaps in the parylene layer 122 — may allow multi-dimensional flexibility, both in the horizontal direction and a normal direction to an electrode plane of the flexible electrode.

[43] In some embodiments, the kirigami patterns are not identical to each other. For example, the kirigami structure 134a may include non-identical kirigami patterns 136a and 138a. In other embodiments, the kirigami patterns are identical to each other. For example, the kirigami structure 134b has identical kirigami patterns 136b and 138b. Regardless of the types of the kirigami patterns 136a, 136b, 138a, and 138b; these kirigami patterns may allow both horizontal and vertical stretching. For instance, during a vertical stretching, the gap between the first kirigami pattern 136a and the second kirigami pattern 138a may increase. Similarly, during a vertical stretching (along a normal direction of an electrode plane of the fabricated flexible electrode), the gap between the first kirigami pattern 136b and second kirigami pattern 138b may increase.

[44] FIG. 2A shows a top view of illustrative flexible electrodes 200 with kirigami structures 201, according to example embodiments of this disclosure. Particularly, some example flexible electrodes 200 have been shown, one of which has been expanded for a detailed view. The flexible electrode 200 shown in the detailed view may have a width of approximately 10 mm and the length of approximately 20 mm (just as an example and not intended to be limiting). Within the flexible electrode 200, the kirigami structure 201 may include multiple linear etches 202 with corresponding end apertures 204, which may allow for a horizontal stretching of the kirigami structure 201 (e.g., along its length and/or width). The linear etches 202 and the end apertures 204 may be formed by kirigami patterns 136a, 136b on the top layer of the corresponding kirigami structures 134a, 134b shown in FIG. IB. [45] FIG. 2B shows example dimensions of kirigami structures 201 shown in FIG. 2A, according to example embodiments of this disclosure. It should be understood these example dimensions are just for illustration only and should not be considered limiting. As shown, a linear etch 202 may have a length of approximately 2 mm. The perpendicular distance between two linear etches 202 may be approximately 0.4 mm. The co-linear distance between two linear etches 202 may be approximately 0.4 mm. The diameter of an end aperture 204 may be approximately 0. 1 mm.

[46] FIG. 3A shows a flow diagram of the method 300 of fabricating a flexible electrode with a kirigami structure and silane protection, according to example embodiments of this disclosure. FIG. 3B illustrates progress of flexible electrode fabrication associated with the steps discussed in FIG. 3A, according to example embodiments of this disclosure. In addition to generating the kirigami structure, the method 300 applies a silane layer within the flexible electrode.

[47] At step 304, a parylene layer 322 may be formed by applying a parylene coating on a substrate 320. In some embodiments, the substrate 320 may include a glass material. In some embodiments, the parylene layer 322 may have a thickness of approximately 5 pm.

[48] At step 306, a mask pattern 324 may be applied on the parylene layer 322.

[49] At step 308, a silane layer 325 may be applied on top of the mask pattern 324. The silane layer 325 may provide protection to the underlying layers.

[50] At step 310, another parylene layer 323 may be added on top of the silane layer 325. Therefore, the silane layer 325 may be sandwiched in between the two parylene layers 323, 322.

[51] At step 312, the second parylene layer 323 may be sculpted to generate a flexible electrode with a kirigami structure and silane protection. In some embodiments, the sculpting may be performed by etching selective portions of the second parylene layer 323.

[52] FIG. 4A shows a flow diagram of a method 400 of fabricating a flexible electrode with a kirigami structure and silane protection, according to example embodiments of this disclosure. FIG. 4B illustrates progress of flexible electrode fabrication associated with the steps discussed in FIG. 4A, according to example embodiments of this disclosure. The method 400 may be used to fabricate a flexible electrode with an alternate kirigami structure compared to methods 100, 300.

[53] At step 402, a parylene coating may be applied on a substrate 451 (e.g., formed by glass) to form a parylene layer 452. In some embodiments, the parylene layer 452 may have a thickness of approximately 5 pm.

[54] At step 403, an aluminum coating may be applied on the parylene layer 452 to form an aluminum layer 453. The aluminum layer 453 may be configured to protect portions of the underlying parylene layer 452 during a plasma etching of the parylene layer.

[55] At step 404, a first mask pattern 454 may be applied on the aluminum layer 453.

[56] At step 405, an aluminum etching may be performed on the aluminum layer 453 to remove exposed portions (e.g., not covered by the first mask pattern 454) of the aluminum layer 453. [57] At step 406, plasma etching (e.g., oxygen plasma etching) may be performed to remove exposed portions (e.g., not covered by the first mask pattern 454 and the aluminum layer 453) of the parylene layer 452.

[58] At step 407, the remaining portions of the aluminum layer 453 may be removed.

[59] At step 408, a silane layer 455 may be applied on the electrode structure, i.e., on the remaining portion of the parylene layer 452 and the exposed portion of the substrate 451.

[60] At step 409, a parylene coating may be applied on the silane layer 455 to form another parylene layer 456.

[61] At step 410, an aluminum coating may be applied on top of the parylene layer 456 to form another aluminum layer 457.

[62] At step 411, a second mask pattern 458 may be applied on the aluminum layer 457.

[63] At step 412, an aluminum etching may be performed to remove the exposed portions (i.e., exposed through the mask pattern 458) of the aluminum layer 457.

[64] At step 413, a plasma etching may be performed to remove the exposed portions of the parylene layer 456.

[65] At step 414, remaining portions of the aluminum layer 457 may be removed. The result may be a flexible electrode having a kirigami structure formed by parylene layers 452 (forming a first kirigami pattern), 456 and a silane layer 455 (forming a second kirigami pattern).

[66] FIG. 5 A shows a flow diagram of a method 500 of fabricating a flexible electrode with a kirigami structure and silane protection, according to example embodiments of this disclosure. FIG. 5B illustrates progress of flexible fabrication associated with the steps discussed in FIG. 5A, according to example embodiments of this disclosure. The method 500 may be used to fabricate a flexible electrode with an alternate kirigami structure compared to methods 100, 300, 400.

[67] At step 502, parylene coating may be applied on a substrate 581 (e.g., formed of glass) to form a parylene layer 582. In some embodiments, the parylene layer 582 may have a thickness of approximately 5 pm.

[68] At step 503, an aluminum coating may be applied on the parylene layer 582 to form an aluminum layer 583. The aluminum layer 583 may protect portions of the underlying parylene layer 582 during a plasma etching of the parylene layer 582.

[69] At step 504, a first mask pattern 584 may be applied on the aluminum layer 583.

[70] At step 505, an aluminum etching may be performed to remove exposed portions (e.g., exposed through the first mask pattern 584) of the aluminum layer 583.

[71] At step 506, a plasma etching (e.g., oxygen plasma etching) may be performed to remove exposed portions of the parylene layer 582.

[72] At step 507, the remaining portions of the aluminum layer 583 may be removed. [73] At step 508, a second mask pattern 585 may be applied at a portion of the etched parylene layer 582.

[74] At step 509, a silane layer 586 may be applied on the non-masked portions of the etched parylene layer 582.

[75] At step 510, another parylene coating may be applied to form another parylene layer 587.

[76] At step 511, aluminum coating may be applied on top of the parylene layer 587 to form another aluminum layer 588.

[77] At step 512, a third mask pattern 589 may be applied on the aluminum layer 588.

[78] At step 513, an aluminum etching may be performed to remove exposed portions (e.g., through the third mask pattern 589) of the aluminum layer 588.

[79] At step 514, plasma etching (e.g., oxygen plasma etching) may be performed to remove the exposed portions of the parylene layer 587.

[80] At step 515, the remaining portion of the aluminum layer 588 may be removed.

[81] The result is flexible electrode having kirigami structure formed by parylene layers 582 (forming a bottom kirigami pattern), 587 (forming a top kirigami pattern) and a silane layer 586.

[82] FIG. 6A shows a process 602a illustrating how silaning may protect underlying layers, according to example embodiments of this disclosure.

[83] The process 602a may begin with applying parylene layer 606a on a substrate 608a (e.g., made of glass). On top of the parylene layer 606a, a Polydimethylsiloxane (PDMS) mask 610a may be applied. A silane layer 604 may be applied to cover the PDMS mask 610a and the parylene layer 606a exposed through the PDMS mask 610a. The resulting structure may undergo oxygen plasma etching 612a, during which the silane layer 604 may protect the underlying PDMS mask 610a and the parylene layer 606a exposed through the PDMS mask 610a. More particularly, the oxygen plasma etching 612a may change the chemical structure of the silane layer 604, but the layers underlying the silane layer 604 may be protected.

[84] FIG. 6B shows another process 602b illustrating how silaning may protect underlying layers, according to example embodiments of this disclosure. The process 602b may begin with applying parylene layer 606b on a substrate 608a (e.g., made of glass). On top of the parylene layer 606b, a PDMS mask 610b may be applied. A silane layer 604 may be applied to cover the PDMS mask 610b and portions of the parylene layer 606b exposed through the PDMS mask 610b. The resulting structure may undergo acetone etching 614. The acetone etching 614 may not change the chemical structure of the silane layer 604. The PDMS mask 610b may then be removed and silane layer 604 may be added to the exposed areas of the substrate 608b (it should be understood that the silane layer 604 is already on top of the remaining portion of the parylene layer 606b). After the addition of the silane layer 604, the layered structure may undergo oxygen plasma etching 612b. The oxygen plasma etching 612b may change the chemical structure of the silane layer 604 but the underlying structure, in this case a portion of the parylene layer 606b and an exposed portion of the substrate 608b, may remain protected.

[85] FIG. 6C shows yet another process 602b illustrating how silaning may protect underlying layers, according to example embodiments of this disclosure. The process 602c may begin with applying parylene layer 606c on a substrate 608c (e.g., made of glass). On top of the parylene layer 606c, a PDMS mask 610c may be applied. A silane layer 604 may be applied — covering the PDMS mask 610c and portions of the parylene layer 606c exposed through the PDMS mask 610c. This layer structure may undergo one or more etching processes, e.g., acetone etching, after which the PDMS mask may be removed. The resulting structure may show that the silane layer 604 has protected the underlying parylene layer 606c.

[86] Therefore, these example processes 602a, 602b, 602c illustrate that the silane layer 604 may protect underlying layers of an electrode and the tissue/cell structure underneath the electrode against different electrical and chemical activities.

[87] FIG. 7A shows a flow diagram of the method 700 of fabricating a kirigami structure, according to example embodiments of this disclosure. FIG. 7B illustrates progress of flexible electrode fabrication associated with the steps discussed in FIG. 7A, according to example embodiments of this disclosure. The method 700 may generate a flexible electrode that is optimized for better peeling off from a glass substrate.

[88] At the beginning step 702, a glass 730 may be cleaned. The glass 730 may form a substrate for generating the flexible electrode having a kirigami structure.

[89] At step 704, the glass 730 may be aligned using alignment markers 732.

[90] At step 706, a parylene coating may be applied on the glass 730 forming a parylene layer 734.

[91] At step 708, a first mask pattern 736 may be applied on the parylene layer 734.

[92] At step 710, a parylene coating may be applied on top of the first mask pattern 736 to increase the thickness of the parylene layer 734.

[93] At step 712, a chromium (Cr) layer 738 may be deposited on top of the parylene layer 734.

[94] At step 714, a second mask pattern 740 may be applied, where the second mask pattern 740 may define the kirigami structure on the Cr layer 738.

[95] At step 716, a third mask pattern 742 may be applied on the second mask pattern 740.

[96] At step 718, the Cr layer 538 may be removed to expose the parylene layer 734.

[97] At step 720, an etching (e.g., oxygen plasma etching) may be performed thereby generating the kirigami structure 744. In some embodiments a layer of gelatin may be applied as a sacrificial layer between the glass 730 and the parylene layer 734 for a better peeling off of the flexible electrode from the glass 730.

[98] FIG. 8 shows an illustrative process 800 of demonstrating silane protection, according to example embodiments of this disclosure. [99] At step 802, a substrate 812 (e.g., a glass substrate) may be prepared. As shown, the substrate 812 may have a length of approximately 24 mm and a width of approximately 24 mm (just example measurements and not to be construed as limiting). At step 804, an organic material coating 814 may be added on the substrate 812. The organic material coating 814 may include cells, tissues, and/or any other type of organic material. At step 806, a PDMS mask 816 may be applied on top of the organic material. At a silanization step 808, a silane layer 818 may be added on top of the PDMS mask 816. At step 810, oxygen etching may be performed to demonstrate that the silane layer 818 protects the organic material coating 814 underneath the silane layer 818.

[100] FIG. 9 shows an illustrative flexible electrode 902 having a kirigami structure 906, according to example embodiments of this disclosure. As shown, the flexible electrode 902 may conform to (e.g., wrap around) an organ 908 (e.g., a heart). The flexible electrode 902 may be connected through a connection 910 to an electronic circuitry 904 that may measure electrical activity of the organ 908 and/or provide electrical stimulation to the organ 908. The kirigami structure 906 — being stretchable in any direction — may allow for a snug fitting of the flexible electrode 902 around the organ 908. Furthermore, a silane layer in the flexible electrode 902 may protect the cells underneath the flexible electrode 902 from external chemical and/or radiative activities.

[101] FIG. 10 shows a flow diagram of an illustrative method 1000 of using a flexible electrode, according to example embodiments of this disclosure.

[102] At method may begin at step 1002, the flexible electrode may be stretched to conform to a contour of a human organ. The stretching may be in one or more of a vertical direction and a horizontal direction. The stretching in the horizontal direction may include stretching along a length or a width of the flexible electrode. The stretching in the vertical direction may include stretching along a normal direction of an electrode plane of the flexible electrode.

[103] At step 1004, stretched flexible electrode may be adhered to the human organ. The flexible electrode may be connected to an electronic circuity that measures the electrical activity of the human organ and/or provides electrical stimulation to the human organ.

[104] 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.

[105] 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. [106] 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.

[107] 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

CLAIMS What is claimed is:

1. A flexible electrode comprising: a bottom parylene layer etched with a first kirigami pattern; a top parylene layer etched with a second kirigami pattern, the first kirigami pattern and the second kirigami pattern forming a kirigami structure configured to allow a stretching of the flexible electrode in one or more of a horizontal direction and a vertical direction; and a silane layer in between the first kirigami pattern and the second kirigami pattern, the silane layer configured to protect the first kirigami pattern.

2. The flexible electrode of claim 1 , wherein the stretching of the flexible electrode in the horizontal direction comprises stretching along a length or a width of the flexible electrode.

3. The flexible electrode of claim 1, wherein the stretching of the flexible electrode in the vertical direction comprises stretching along a normal direction of an electrode plane of the flexible electrode.

4. The flexible electrode of claim 3, wherein the first kirigami pattern and the second kirigami pattern are configured to increase a gap to allow for the stretching in the normal direction of the electrode plane.

5. The flexible electrode of claim 1, wherein the first kirigami pattern and the second kirigami pattern are identical to each other.

6. The flexible electrode of claim 1, wherein the first kirigami pattern and the second kirigami pattern are different from each other.

7. The flexible electrode of claim 1, wherein the silane layer is further configured to protect organic material underneath the flexible electrode.

8. A method of fabricating a flexible electrode, the method comprising: coating a first parylene layer on a substrate; applying a first mask pattern on the first parylene layer; generating a first kirigami pattern by etching the first parylene layer through the first mask pattern; coating the etched first parylene layer with a silane layer; coating the silane layer with a second parylene layer; applying a second mask pattern on the second parylene layer; and generating a second kirigami pattern by etching the second parylene layer through the second mask pattern, the first kirigami pattern and the second kirigami pattern forming a kirigami structure configured to allow a stretching of a fabricated flexible electrode in one or more of a horizontal direction and a vertical direction.

9. The method of claim 8, wherein the etching is performed using oxygen plasma etching.

10. The method of claim 8, wherein the etching is performed using acetone etching.

11. The method of claim 8, further comprising: applying an aluminum layer on the first parylene layer prior to applying the first mask pattern; and aluminum etching the aluminum layer through the first mask pattern to expose portions of the first parylene layer for the etching of the first parylene layer, non-etched portions of the aluminum layer configured to protect non-exposed portions of the first parylene layer.

12. The method of claim 8, further comprising: generating the second kirigami pattern to be different from the first kirigami pattern.

13. The method of claim 8, further comprising: generating the second kirigami pattern to be same as the first kirigami pattern.

14. The method of claim 8, further comprising: applying a sacrificial layer between the substrate and the first parylene layer, the sacrificial layer configured to facilitate peeling off of the flexible electrode from the substrate.

15. A method of using a flexible electrode, the method comprising: stretching the flexible electrode in one or more of a horizontal direction and a vertical direction to conform to a contour of a human organ, the flexible electrode formed by a bottom parylene layer etched with a first kirigami pattern, a top parylene layer etched with a second kirigami pattern, and a silane layer in between the first kirigami pattern and the second kirigami pattern, the first kirigami pattern and the second kirigami pattern forming a kirigami structure configured to allow the stretching; and adhering the stretched flexible electrode to the human organ.

16. The method of claim 15, wherein the stretching of the flexible electrode in the horizontal direction comprises stretching along a length or a width of the flexible electrode.

17. The method of claim 15, wherein the stretching of the flexible electrode in the vertical direction comprises stretching along a normal direction of an electrode plane of the flexible electrode.

18. The method of claim 17, wherein the first kirigami pattern and the second kiri garni pattern a gap to allow for the stretching in the normal direction of the electrode plane.

19. The method of claim 15, wherein the first kirigami pattern and the second kirigami pattern are identical to each other.

20. The method of claim 15, wherein the first kirigami pattern and the second kirigami pattern are different from each other.