CN107638175B

CN107638175B - Flexible electrode array-optical fiber composite nerve electrode and preparation method thereof

Info

Publication number: CN107638175B
Application number: CN201710977927.4A
Authority: CN
Inventors: 方英; 邹亮; 王晋芬; 管寿梁
Original assignee: National Center for Nanosccience and Technology China
Current assignee: National Center for Nanosccience and Technology China
Priority date: 2017-08-24
Filing date: 2017-10-17
Publication date: 2020-12-01
Anticipated expiration: 2037-10-17
Also published as: CN107638175A

Abstract

The invention provides a flexible electrode array-optical fiber composite nerve electrode which comprises a flexible electrode array, an optical fiber and a supporting structure, wherein a groove is formed in the surface of the supporting structure, the optical fiber is fixed in the groove, the flexible electrode array comprises a welding spot, an interconnection lead and a recording site which are sequentially connected, the welding spot region is fixed on the surface of the supporting structure, and the interconnection lead and the recording site region are wrapped on the surface of the optical fiber in a curling mode. The composite nerve electrode can be implanted into a specific brain area of a brain after being solidified by polyethylene glycol (PEG), optical signals are introduced by using optical fibers, electrophysiological signal distribution of specific types of neurons in the specific brain area can be stimulated or inhibited, the electrophysiological signals of the neurons are detected by the flexible electrode array, electrophysiological signal detection and a light genetic technology can be organically combined, and the composite nerve electrode has important application value for researches on neural circuits, neural diseases, neural prostheses and the like.

Description

Flexible electrode array-optical fiber composite nerve electrode and preparation method thereof

Technical Field

The invention relates to the technical field of neuroscience and biological instrument engineering, in particular to a flexible electrode array/optical fiber composite nerve electrode and a preparation method thereof.

Background

The neural electrode is a hot research content of a brain-computer interface technology, can provide an information interaction interface of a cerebral neuron and an electronic system, and has important application prospects in the aspects of neural cognitive behaviors, disease treatment and the like. The existing nerve electrodes comprise electroencephalogram (EEG) electrodes, cortex of brain (ECoG) electrodes and implanted electrodes, wherein the implanted nerve electrodes, especially implanted nerve electrode arrays, can distinguish the electrical activity of single nerve cells through action potentials, and realize the simultaneous detection of high space-time resolution and large-range neuron electrical activity. The implanted nerve electrode array usually adopts part of channels to electrically stimulate and induce the electrical discharge of nerve cells, and the rest channels detect the electrical discharge signals of the nerve cells. The main principle of the stimulation electrode is to directly apply electric field disturbance and conduct the disturbance to a specific brain area of the brain through an electrode array, so that all nerve cells near the brain area are forcibly issued. The electrical stimulation mode has the advantages that the nerve electrical activity can be directly influenced, and the platform is easy to construct. However, because the electric field applied by the electric stimulation is wide in range and has no directivity, the normal electric activity of the incoherent brain area around the target brain area is interfered in the transmission process, and the incoherent brain area is activated by mistake; in addition, electrical stimulation tends to activate all types of neurons (or even glial cells) in the targeted brain region, making it difficult to detect the activity of a particular type of neuron in a particular brain region.

The optogenetics refers to a technology for accurately controlling the neuron activity of a specific brain region by combining optics and genetics, and the technology integrates optics, software control, gene operation, electrophysiology and other multidisciplinary cross technologies. The main principle is that the gene manipulation technology is adopted to transfer the light sensing gene into a cell of a specific type in a nervous system to express a special ion channel or a G Protein Coupled Receptor (GPCR). The light sensitive ion channel can respectively generate selectivity to the passing of cations or anions under the stimulation of illumination with different wavelengths, thereby changing the membrane potential of the cell membrane and achieving the purpose of selectively exciting or inhibiting cells. The technology overcomes the defect of controlling cell activity by the traditional means, has two characteristics of unique space-time resolution and cell type specificity, and can perform accurate positioning stimulation operation on neurons.

The photoelectric composite electrode is additionally provided with a light transmission channel on the basis of the original recording electrode, so that electrophysiological recording is carried out while light is used for stimulating specific type neurons in a specific brain region. The most commonly used photoelectric composite electrode is realized by integrating an optical fiber and a microwire electrode, and the photoelectric composite electrode is economical and practical, but has great limitations on space precision and mechanical performance. Therefore, there is a need to develop a photoelectric composite electrode having a new structure and applying a new material.

Disclosure of Invention

The composite nerve electrode prepared by the invention can be implanted into a specific brain area of a brain after being cured, optical signals are led in by using optical fibers, electrophysiological signal distribution of neurons in the specific brain area can be stimulated or inhibited, the electrophysiological signals of the neurons are detected by the flexible electrode array, electrophysiological signal detection and optogenetic technology can be organically combined, and the composite nerve electrode has important application value for researches on neural circuits, nerve diseases, nerve prostheses and the like.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention aims to provide a flexible electrode array-optical fiber composite nerve electrode which comprises a flexible electrode array, optical fibers and a supporting structure, wherein a groove is formed in the surface of the supporting structure, the optical fibers are fixed in the groove, the flexible electrode array comprises three areas, namely a welding spot, an interconnection lead and a recording site, which are sequentially connected, the welding spot area is fixed on the surface of the supporting structure, and the interconnection lead and the recording site area are wrapped on the surface of the optical fibers in a curling mode.

The flexible electrode array has good flexibility and hydrophilicity, and is wrapped on the surface of the optical fiber in a curling manner under the action of liquid surface tension and van der Waals force between liquid and the electrode, wherein the optical fiber can guide a recording site.

As a preferable technical scheme of the invention, the flexible electrode array comprises a flexible substrate layer, a conductive layer and a flexible insulating layer which are sequentially connected.

Preferably, the pad area of the flexible electrode array is bonded to the base silicon wafer through a flexible substrate layer.

Preferably, the welding spot area is connected with the substrate silicon wafer and fixed on the surface of the supporting structure at the side provided with the groove.

Preferably, the flexible electrode array is fixed to the surface of the support structure on the side provided with the groove.

As a preferred technical solution of the present invention, the raw materials of the flexible substrate layer and the flexible insulating layer respectively and independently comprise any one of SU8 photoresist, polyimide or parylene, or a combination of any at least two of the foregoing, and typical but non-limiting examples of the combination are: a combination of SU8 photoresist and polyimide, a combination of polyimide and parylene, a combination of parylene and SU8 photoresist, or a combination of SU8 photoresist, polyimide and parylene, and the like.

Preferably, the thickness of the flexible substrate layer is 0.5 to 10 μm, such as 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm, but is not limited to the recited values, and other values not recited within this range are equally applicable, preferably 1 to 8 μm, and more preferably 5 μm.

Preferably, the thickness of the flexible insulating layer is 0.5 to 10 μm, such as 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm, but is not limited to the recited values, and other values not recited in the numerical range are also applicable, preferably 0.5 to 5 μm, and more preferably 0.5 μm.

Preferably, the raw material of the conductive metal layer comprises any one or a combination of at least two of gold, platinum or iridium, typical but non-limiting examples of which are: combinations of gold and platinum, platinum and iridium, iridium and gold, or gold, platinum and iridium, and the like.

Preferably, the thickness of the conductive metal layer is 20 to 500nm, such as 20nm, 30nm, 40nm, 50nm, 80nm, 100nm, 150nm, 200nm, 250nm, 300nm, 400nm or 500nm, but not limited to the listed values, and other values not listed in the range of the values are also applicable, preferably 50 to 300nm, and more preferably 200 nm.

Preferably, an adhesion layer is disposed between the flexible insulating layer and the conductive metal layer.

Preferably, the raw material of the adhesion layer includes chromium or tantalum.

Preferably, the thickness of the adhesive layer is 1 to 50nm, such as 1nm, 2nm, 5nm, 8nm, 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm or 50nm, but not limited to the recited values, and other values not recited within the range of the values are also applicable, preferably 3 to 15nm, and more preferably 5 nm.

As a preferred technical solution of the present invention, the flexible electrode array is provided with recording sites.

Preferably, the recording site is circular in shape.

Preferably, the number of the recording sites is 1 to 800, such as 1, 10, 20, 50, 100, 200, 300, 400, 500, 600, 700, or 800, but not limited to the enumerated values, and other non-enumerated values within the range of the enumerated values are also applicable, preferably 1 to 100, and more preferably 10.

Preferably, the diameter of the recording sites is 5 to 40 μm, such as 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm or 40 μm, but is not limited to the values listed, and other values not listed in this range are also applicable, preferably 10 to 30 μm, and more preferably 10 μm.

Preferably, when the number of the recording sites is more than 1, the pitch of the recording sites is 50 to 500. mu.m, such as 50. mu.m, 100. mu.m, 150. mu.m, 200. mu.m, 250. mu.m, 300. mu.m, 350. mu.m, 400. mu.m, 450. mu.m, or 500. mu.m, but not limited to the above-mentioned values, and other values not shown in the above-mentioned range are also applicable, preferably 100 to 200. mu.m, and more preferably 150. mu.m.

As a preferred technical scheme of the invention, the nerve electrode is prepared by adopting a micro-nano processing method.

Preferably, the micro-nano processing method comprises the steps of sputtering a sacrificial layer, photoetching or etching to form a substrate layer, evaporating a metal conducting layer, photoetching or etching to form an insulating layer and corroding the sacrificial layer.

In a preferred embodiment of the present invention, the length of the optical fiber is 2 to 180mm, such as 2mm, 5mm, 10mm, 20mm, 50mm, 80mm, 100mm, 120mm, 150mm, or 180mm, but is not limited to the above-mentioned values, and other values not shown in the above-mentioned range are also applicable, preferably 10 to 50mm, and more preferably 25 mm.

Preferably, the diameter of the optical fiber is 100 to 400 μm, such as 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, or 400 μm, but is not limited to the recited values, and other values not recited within the range of the values are also applicable, preferably 100 to 300 μm, and more preferably 200 μm.

Preferably, the optical fiber has a numerical aperture of 0.22 to 0.48, such as 0.22, 0.25, 0.28, 0.30, 0.32, 0.35, 0.38, 0.40, 0.42, 0.45, or 0.48, but not limited to the recited values, and other values not recited within the range of values are equally applicable.

Preferably, the diameter of the sleeve is 1.25 to 2.50mm, such as 1.25mm, 1.30mm, 1.40mm, 1.50mm, 1.80mm, 2.00mm, 2.20mm, 2.40mm or 2.50mm, but not limited to the recited values, and other values not recited in the range of values are equally applicable.

In a preferred embodiment of the present invention, the support structure is made of polylactic acid.

Preferably, the length of the support structure is 1 to 100mm, such as 1mm, 2mm, 5mm, 8mm, 10mm, 20mm, 50mm, 80mm or 100mm, but not limited to the recited values, and other values within the range are equally applicable, preferably 10 to 30mm, and more preferably 18 mm.

Preferably, the width of the support structure is 5-100 mm, such as 5mm, 8mm, 10mm, 15mm, 20mm, 25mm, 30mm, 50mm, 60mm, 70mm, 80mm, 90mm or 100mm, but not limited to the recited values, and other values not recited in the range of values are also applicable, preferably 10-20 mm, and more preferably 15 mm.

Preferably, the thickness of the support structure is 0.5 to 5mm, such as 0.5mm, 1mm, 1.5mm, 2mm, 3mm, 4mm or 5mm, but not limited to the recited values, and other values not recited within the range of values are equally applicable, preferably 0.8 to 2mm, and more preferably 1 mm.

Preferably, the diameter of the grooves in the support structure is 1.15-2.40 mm, such as 1.15mm, 1.20mm, 1.25mm, 1.30mm, 1.50mm, 1.80mm, 2.00mm, 2.20mm or 2.40mm, but not limited to the recited values, and other values not recited in this range are equally applicable.

The supporting structure is prepared by a 3D printing method.

The second objective of the present invention is to provide a method for preparing the above-mentioned neural electrode, the method comprising the steps of:

(1) fitting a ferrule at one end of the optical fiber in a groove of the support structure;

(2) fixing one side of a flexible electrode array substrate silicon wafer on the surface of one side of the supporting structure, which is provided with the groove;

(3) placing a support structure equipped with an optical fiber and a flexible electrode array in water;

(4) aligning the flexible electrode array with the optical fiber, and fishing out from water to enable the flexible electrode array to be wrapped on the surface of the optical fiber in a curling manner;

(5) and putting the flexible electrode array/optical fiber composite nerve electrode into a high-temperature melted curing material for curing treatment to obtain the flexible electrode array-optical fiber composite nerve electrode.

As a preferred technical scheme of the invention, the curing material in the step (5) is polyethylene glycol.

Preferably, the molecular weight of the polyethylene glycol is 1000 to 8000, such as 1000, 2000, 3000, 4000, 5000, 6000, 7000 or 8000, but not limited to the recited values, and other values not recited in the range of the values are also applicable, preferably 1000 to 4000, and more preferably 2000.

And (3) fixing the flexible electrode array and the supporting structure in the flexible electrode array-optical fiber composite nerve electrode obtained in the step (5) by using a copper adhesive tape as a preferable technical scheme of the invention.

Compared with the prior art, the invention at least has the following beneficial effects:

(1) the flexible electrode array-optical fiber composite nerve electrode is different from a conventional photoelectric composite nerve electrode, and adopts a flexible electrode array, and the flexible electrode array has better flexibility, hydrophilicity and biocompatibility, can be coated on the surface of an optical fiber, and reduces the damage of implantation;

(2) the flexible electrode array-optical fiber composite nerve electrode is prepared by a micro-nano processing technology, can accurately control the vertical direction spacing and the horizontal plane distribution of each recording site, and can detect three-dimensional signals of a brain.

Drawings

Fig. 1a is a schematic structural diagram of a flexible electrode array-optical fiber composite nerve electrode provided by the invention;

FIG. 1b is an exploded view of the structure of the flexible electrode array-optical fiber composite nerve electrode provided by the present invention;

FIG. 2a is a schematic structural diagram of a substrate layer of a flexible electrode array of the flexible electrode array-optical fiber composite nerve electrode provided by the invention;

fig. 2b is a schematic structural diagram of a conductive layer of a flexible electrode array of the flexible electrode array-optical fiber composite neural electrode provided by the invention;

FIG. 2c is a schematic structural diagram of an insulating layer of a flexible electrode array of the flexible electrode array-optical fiber composite neural electrode provided by the present invention;

FIG. 2d is a schematic structural diagram of a flexible electrode array of the flexible electrode array-optical fiber composite neural electrode provided by the present invention;

fig. 3 is a micro-nano processing process diagram of a flexible electrode array of the flexible electrode array-optical fiber composite neural electrode provided in embodiment 1 of the present invention;

fig. 4a is a schematic diagram of the arrangement of recording sites of a flexible electrode array of the flexible electrode array-optical fiber composite neural electrode provided by the invention;

fig. 4b is a schematic diagram of the arrangement of the recording sites of the flexible electrode array-optical fiber composite neural electrode provided by the invention;

fig. 4c is a schematic diagram of the arrangement of the recording sites of the flexible electrode array-optical fiber composite neural electrode provided by the invention;

FIG. 5 is a diagram of a flexible electrode array-optical fiber composite nerve electrode provided by the present invention;

FIG. 6 is a tip photomicrograph of the flexible electrode array-fiber composite neural electrode real object shown in FIG. 5;

FIG. 7 is a diagram of an animal experiment object of the flexible electrode array-optical fiber composite nerve electrode provided by the invention;

description of reference numerals:

1-a solder joint area; 2-interconnect wire region; 3-recording site region; 4-an optical fiber; 5-a support structure; 6-substrate silicon wafer; 7-a flexible electrode array; 8-a substrate layer; 9-a conductive layer; 10-an insulating layer; 11-a flexible electrode array; 12-a silicon wafer; 13-spin coating; 14-S1813 photoresist; 15-exposure; 16-developing; 17-magnetron sputtering; an 18-Al layer; 19-stripping; 20-spin coating; 21-SU82005 photoresist; 22-exposure; 23-developing; 24-spin coating; 25-AZ4620 photoresist; 26-exposure; 27-developing; 28-thermal evaporation; a 29-Au layer; 30-stripping; 31-whirl coating; 32-SU82000.5 photoresist; 33-exposure; 34-developing.

Detailed Description

To better illustrate the invention and to facilitate the understanding of the technical solutions thereof, typical but non-limiting examples of the invention are as follows:

example 1

Flexible electrode array preparation

1. Designing an electrode;

(1) grid-shaped electrode:

welding spots: the rectangular, the length is 2mm, the width is 0.7mm, the interval is 1mm, 10 channels are evenly arranged.

Recording site: circular, 30 μm in diameter, and arranged as shown in FIG. 4.

Substrate layer SU8-1 layer: the thickness is 5 μm, the width of the horizontal bar is 20 μm, the length is 1.115mm, and the distance is 500 μm; the width of the longitudinal bar is 35 μm, and the length is 15 mm. The electrode longitudinal strips are connected with the flat cable part in an increased arc manner, so that stress concentration is avoided.

Conductive layer Au layer: the width of the conductive Au line is 15 mu m, the thickness of the conductive Au line is 100nm, and the thickness of the adhesion layer Cr layer is 5 nm.

Insulating layer SU8-2 layer: the thickness is 0.5 μm, and the difference with SU8-1 lies in the following points, the disc electrode with the recording site diameter of 30 μm is exposed, the first channel and the tenth channel are completely exposed as the built-in grounding and reference, the welding point is removed from the back part, so that the ACF glue is stressed when the flexible flat cable is pressed.

(2) Comb-shaped electrodes:

welding spots: rectangular, 1mm long, 0.2mm wide, 0.5mm apart from, 18 passageways of uniform arrangement.

Recording site: circular, 30 μm in diameter.

Substrate layer SU8-1 layer: the thickness is 5 μm, the width of the horizontal bar is 50 μm, the length is 3.44mm, and the distance is 150 μm; the width of the longitudinal bar is 35 μm, the length is 15mm, and the solid bar is 3 mm/grid 7 mm/comb teeth 5 mm. The front end is made into a triangular pointed shape, which is beneficial to the implantation of the electrode. The electrode longitudinal strips are connected with the flat cable part in an increased arc manner, so that stress concentration is avoided.

Insulating layer SU8-2 layer: the thickness is 0.5 μm, and the difference with SU8-1 lies in the following points, the disc electrode with the recording site diameter of 30 μm is exposed, the first channel and the eighteenth channel are completely exposed as the built-in grounding and reference, the welding point is removed from the back part, so that the ACF glue is stressed when the flexible flat cable is pressed.

2. The micro-nano processing technology comprises the following steps:

(1) an Al layer:

1) and (3) film washing: placing a silicon wafer with the diameter of four inches in a culture dish, respectively carrying out ultrasonic treatment for 10min at room temperature by using acetone, isopropanol and water with the power of 60W, placing the silicon wafer on a hot plate at 100 ℃ after drying the silicon wafer by using nitrogen, heating for 3min, removing water vapor, cooling to room temperature, and then beating for 3min by using the power of 100W of oxygen plasma.

2) Spin coating: the cleaned silicon wafer is placed in the center of a sucker of a spin coater to be fixed, the parameters of the spin coater (500rpm10S &2000rpm60S) are adjusted, a proper amount of S1813 glue is dripped to the center of the silicon wafer by a dropper, a protective cover of the spin coater is covered, and spin coating is started.

3) Pre-baking: and placing the silicon wafer with the glue thrown thereon on a hot plate at 115 ℃ and pre-baking for 3 min.

4) Exposure: and opening the MA6 ultraviolet photoetching machine, fixing an Al layer mask plate, placing the pre-baked silicon wafer, and exposing for 65 s.

5) And (3) developing: placing the exposed silicon wafer in an S1813 developing solution for developing for 1min, then flushing with water, and drying by high-pressure nitrogen;

6) removing residual glue: placing the silicon wafer on a hot plate at 100 ℃, baking for 30s, etching for 1min by using an oxyden plasma 50W power, and removing residual glue;

7) and (3) depositing aluminum: and depositing an Al layer with the thickness of 100nm on the silicon wafer by using a magnetron sputtering instrument.

8) Stripping: and placing the silicon wafer subjected to Al sputtering in a culture dish containing a proper amount of acetone, stripping out a required pattern, cleaning and drying by using high-pressure nitrogen for later use after the silicon wafer is cleaned and returned to the Beijing.

(2) Substrate layer SU8 layer/insulating layer SU8 layer:

1) and (3) film washing: and (3) placing the silicon wafer with the Al layer stripped on a hot plate at 100 ℃ for heating for 30s, airing to room temperature, and then cleaning for 3min by using an oxygen plasma 100W power.

2) Spin coating: the silicon chip is placed in the center of a sucker of a spin coater to be fixed, spin coating parameters (500rpm10s &2000rpm60s) are adjusted, a proper amount of SU82005/SU82000.5 glue is dripped to the center of the silicon chip by a dropper, a protective cover of the spin coater is covered, and spin coating is started.

3) Pre-baking: and placing the silicon wafer subjected to spin coating on a hot plate at the temperature of 95 ℃ for pre-baking for 2 min.

4) Exposure: and opening the MA6 ultraviolet photoetching machine, fixing a substrate SU 8/insulating SU8 layer mask plate, placing the pre-baked silicon wafer, and exposing for 120s/150 s.

5) Post-baking: placing the exposed silicon wafer on a hot plate at 95 ℃, and post-baking for 2 min; .

6) And (3) developing: and (3) placing the post-baked silicon wafer in SU8developer for development for 1min, washing with isopropanol after the development is finished, and drying with high-pressure nitrogen.

7) Removing residual glue: heating the silicon wafer on a hot plate at 100 ℃ for 30s, completely drying the silicon wafer, cooling to room temperature, and then beating for 1min with the power of oxygen plasma 50W, and removing residual glue.

8) Hardening the film: after the residual glue removing operation, the silicon wafer is placed on a hot plate at 180 ℃ for hardening for 30 min.

(3) An Au layer:

1) spin coating: after the SU8 layer substrate is formed, the silicon wafer is placed in the center of a sucker of a spin coater to be fixed, parameters of the spin coater are well adjusted (1500rpm 5s &4000rpm 60s), a proper amount of AZ4620 glue is uniformly dripped to the center of the silicon wafer by a dropper, a protective cover of the spin coater is covered, and spin coating is started.

3) Pre-baking: and (3) placing the silicon wafer subjected to spin coating on a hot plate at 120 ℃ and pre-baking for 90 s.

4) Exposure: and opening the MA6 ultraviolet photoetching machine, fixing the Au layer mask plate, and exposing for 180s in a hard mode.

5) And (3) developing: and (3) developing the silicon wafer in an AZ4620 developing solution for 1min, and then flushing the silicon wafer with water and drying the silicon wafer with nitrogen for later use.

6) Removing residual glue: and heating the silicon wafer on a hot plate at 100 ℃, baking for 30s, airing to room temperature, and cleaning for 1min by using an oxyden plasma 50W power.

7) And (3) depositing Au: and (3) sequentially depositing a 5nm Cr adhesion layer and a 100nm Au conductive layer on the silicon wafer by using an electron beam evaporation instrument or a thermal evaporation instrument.

8) Stripping: and placing the silicon wafer coated with Au by evaporation in a culture dish containing a proper amount of acetone, stripping the required pattern, and drying by high-pressure nitrogen for later use.

3. The rear end of the electrode is connected with:

(1) scribing: and lightly scratching the electrode boundary by using a silicon knife, and then lightly pressing two sides of the scratch to crack the silicon wafer. This step is repeated until all electrodes on the silicon wafer are scribed. The scratched electrode was then purged with high pressure nitrogen and placed in a clean disposable plastic petri dish.

(2) Pressing a flexible flat cable: marking alignment marks on ten-channel flexible flat cables, cutting off ACF glue with proper length to cover electrode welding points, aligning the marks of the flexible flat cables with the electrode welding points, and then hot-pressing on a hot plate at 150 ℃ for 60 s.

(3) Packaging: and taking a proper amount of AB glue, uniformly coating the interfaces of the flexible flat cables and the electrodes, placing the flexible flat cables in an oven at 60 ℃ for two hours, and taking out the flexible flat cables.

(4) Etching the sacrificial layer: placing the packaged electrode in 0.5mol/L FeCl₃The solution removes the sacrificial layer aluminum. And cleaning with deionized water after etching, removing redundant silicon wafers, and finally placing in clean deionized water.

Example 2

3D prints bearing structure

Designing a three-dimensional graph of a supporting structure on PROE three-dimensional graph design software; the dimensional parameters were as follows: the length of the support structure is 18 mm; the width of the support structure is 15 mm; the thickness of the support structure is 1 mm; the aperture of the support structure is 2.40 mm; saved in STL format.

And adjusting material parameters and the placement position and mode of a printed matter on the Print-Rite player-Host of the CoLiDo 3D printer matching software, clicking to automatically generate a Slic3r code, storing the code into a printer matching memory card in a GCO format, and starting printing.

Example 3

Flexible electrode array/optical fiber composite nerve electrode

The dimensions of the optical fiber used in the present invention are as follows: sleeve pipe

Optical fiber core

Assembling the optical fiber and the optical fiber support, then placing the electrode on the optical fiber support, and centering the optical fiber and the electrode left and right to enable the electrode to exceed the optical fiber by about 0.5 mm; and then putting the flexible electrode array/optical fiber composite nerve electrode into deionized water, vertically fishing out the flexible electrode array/optical fiber composite nerve electrode to enable the electrode to be wrapped on the surface of the optical fiber in a curling manner, then putting the flexible electrode array/optical fiber composite nerve electrode into a high-temperature melting curing material for curing treatment, and finally fixing the electrode and the supporting structure by using a copper adhesive tape.

Example 4

Flexible electrode array preparation

1. Designing an electrode:

(1) grid-shaped electrode:

Recording site: circular, 10 μm in diameter, and arranged as shown in FIG. 4.

Substrate layer polyimide layer: the thickness is 2 μm, the width of the horizontal bar is 20 μm, the length is 1.115mm, and the distance is 500 μm; the width of the longitudinal bar is 35 μm, and the length is 15 mm. The electrode longitudinal strips are connected with the flat cable part in an increased arc manner, so that stress concentration is avoided.

Conductive layer Pt layer: the width of a conductive Pt line is 15 mu m, the thickness is 150nm, and the thickness of an adhesion layer tantalum layer is 10 nm.

Insulating layer polyimide layer: the thickness is 2 mu m, and the difference with a substrate layer polyimide layer is that the diameter of a recording site is 10 mu m, a disc electrode is exposed, a first channel and a tenth channel are completely exposed to serve as built-in grounding and reference, and welding points are partially removed backwards so that ACF glue is stressed when the flexible flat cable is pressed.

(2) Comb-shaped electrodes:

Recording site: circular, 10 μm in diameter.

Substrate layer polyimide layer: the thickness is 2 μm, the width of the horizontal bar is 50 μm, the length is 3.44mm, and the distance is 150 μm; the width of the longitudinal bar is 35 μm, the length is 15mm, and the solid bar is 3 mm/grid 7 mm/comb teeth 5 mm. The front end is made into a triangular pointed shape, which is beneficial to the implantation of the electrode. The electrode longitudinal strips are connected with the flat cable part in an increased arc manner, so that stress concentration is avoided.

Insulating layer polyimide layer: the thickness is 2 mu m, and the difference with a substrate layer polyimide layer is that a disc electrode with the recording site diameter of 10 mu m is exposed, a first channel and an eighteenth channel are completely exposed to be used as built-in grounding and reference, and welding points are partially removed backwards so that ACF glue is stressed when the flexible flat cable is pressed.

2. The micro-nano processing technology comprises the following steps:

(1) an Al layer:

8) Stripping: and placing the silicon wafer subjected to Al sputtering in a culture dish containing a proper amount of acetone, stripping a required pattern, cleaning, and blow-drying by using high-pressure nitrogen for later use.

(2) Substrate layer polyimide layer/insulating layer polyimide layer:

1) and (3) film washing: the silicon wafer from which the Al or Pt layer was peeled off was placed on a hot plate at 100 ℃ and heated for 30 seconds, followed by appropriate cleaning with an oxygen plasma.

2) Spin coating: the silicon chip is placed in the center of a sucker of a spin coater to be fixed, spin parameters (500rpm10s &2000rpm60s) are adjusted, a dropper is used for dropping a proper amount of polyimide to the center of the silicon chip, the spin coater is covered with a protective cover, and spin coating is started.

3) Pre-baking: and placing the silicon wafer subjected to spin coating on a hot plate at 120 ℃ and pre-baking for 10 min.

4) Post-baking: putting the slices obtained by pre-drying into a vacuum drying oven at 200 ℃, vacuumizing, keeping for two hours, then closing heating, and cooling to room temperature along with the oven;

(3) a Pt layer:

1) and (3) film washing: soaking the substrate polyimide layer in acetone for five minutes, stirring the sheet with tweezers, transferring in isopropanol, washing the sheet with clear water, and blowing the sheet with nitrogen;

2) spin coating: and (3) placing the cleaned wafer in the center of a sucker of a spin coater for fixing, adjusting the parameters of the spin coater (500rpm10S &2000rpm60S), dripping a proper amount of S1813 glue to the center of the silicon wafer by a dropper, covering a protective cover of the spin coater, and starting spin coating.

4) Exposure: and opening the MA6 ultraviolet photoetching machine, fixing a Pt layer mask plate, placing the pre-baked silicon wafer, and exposing for 65 s.

7) depositing Pt: a 10nm thick layer of tantalum and a 150nm thick layer of Pt were deposited in sequence on a silicon wafer using a thermal evaporator.

8) Stripping: and (3) placing the Pt sputtered silicon wafer in a culture dish containing a proper amount of acetone, stripping a required pattern, cleaning, and blow-drying by using high-pressure nitrogen for later use.

(4) AZ4620 mask layer

1) And (3) film washing: soaking the sheet with the insulating polyimide layer in acetone for five minutes, stirring the sheet with tweezers properly, then performing transition in isopropanol, finally washing the sheet with clean water, and drying the sheet with nitrogen;

2) spin coating: placing the cleaned wafer in the center of a sucker of a spin coater for fixing, adjusting parameters of the spin coater (1500rpm10s &2000rpm60s), dripping a proper amount of AZ4620 glue to the center of the silicon wafer by a dropper, covering a protective cover of the spin coater, and starting spin coating;

3) pre-baking: and placing the silicon wafer with the glue thrown thereon on a hot plate at 120 ℃ and pre-baking for 3 min.

4) Exposure: opening the MA6 ultraviolet lithography machine, fixing a mask plate, placing the pre-baked wafer, and exposing for 200 s;

5) and (3) developing: placing the exposed silicon wafer in an AZ4620 developing solution for developing for 3min, then flushing with water, and drying by high-pressure nitrogen;

(5) patterned polyimide

1) Placing the wafer with the AZ4620 mask layer in a reactive ion etcherIn (RIE), RIE parameters (20pa,200W,20sccm O) were adjusted₂) Etching for 7 min; and then opening the machine, and etching for 30-60 s under the same condition according to the etching condition.

2) Cleaning the etched wafer with acetone, then transiting in isopropanol, finally washing the wafer with clean water, and drying the wafer with nitrogen;

3. the rear end of the electrode is connected with:

(2) Pressing a flexible flat cable: marking alignment marks on the ten-channel flexible flat cables, cutting off ACF glue with proper length to cover electrode welding points, aligning the marks of the flexible flat cables with the electrode welding points, and then hot-pressing on a hot plate at 150 ℃ for 90 s.

(4) Etching the sacrificial layer: and placing the packaged electrode in 0.5mol/L FeCl3 solution to remove the sacrificial layer aluminum. And cleaning with deionized water after etching, removing redundant silicon wafers, and finally placing in clean deionized water.

Example 5

3D prints bearing structure

Designing a three-dimensional graph of a supporting structure on PROE three-dimensional graph design software; the dimensional parameters were as follows: the length of the support structure is 20 mm; the width of the support structure is 12 mm; the thickness of the support structure is 0.5 mm; the aperture of the support structure is 2.40 mm; saved in STL format.

Example 6

Flexible electrode array/optical fiber composite nerve electrode

The dimensions of the optical fiber used in the present invention are as follows: ferrule 10.5mm phi 2.5mm, fiber core 25mm phi 100 microns.

Assembling the optical fiber and the optical fiber support, then placing the electrode on the optical fiber support, and centering the optical fiber and the electrode left and right to enable the optical fiber to exceed the electrode by about 0.1 mm; and then putting the flexible electrode array/optical fiber composite nerve electrode into deionized water, vertically fishing out the flexible electrode array/optical fiber composite nerve electrode to enable the electrode to be wrapped on the surface of the optical fiber in a curling manner, then putting the flexible electrode array/optical fiber composite nerve electrode into a high-temperature melting curing material for curing treatment, and finally fixing the electrode and the supporting structure by using a copper adhesive tape.

Example 7

Flexible electrode array preparation

1. Electrode design

Welding spots: rectangular, 1mm long, 1.5mm spacing in the length direction, 0.2mm wide, 0.5mm spacing in the width direction, 800 channels arranged in a matrix of 10 x 80.

Recording site: circular, 40 μm diameter.

Substrate layer poly-p-xylylene layer: the thickness is 10 mu m; the width of the horizontal strips is 50 mu m, the length is 79.960mm, and the spacing is 150 mu m; the width of the longitudinal bar is 60 μm, the length is 150mm, and the solid bar is 40 mm/the grid is 80 mm/the comb teeth is 30 mm. The front end is made into a triangular pointed shape, which is beneficial to the implantation of the electrode. The electrode longitudinal strips are connected with the flat cable part in an increased arc manner, so that stress concentration is avoided.

Conductive layer Ir layer: the width of the conductive Ir line is 15 mu m, the thickness is 500nm, and the thickness of the adhesion layer Cr layer is 50 nm.

Insulating layer parylene layer: the thickness is 10 mu m, and the difference with a substrate layer poly-p-xylene layer is that a disc electrode with the recording site diameter of 40 mu m is exposed, a first channel and an eighth channel are completely exposed to be used as a built-in grounding and reference, and welding points are partially removed backwards so that ACF glue is stressed when the flexible flat cable is pressed.

2. The micro-nano processing technology comprises the following steps:

(1) an Al layer:

1) and (3) film washing: placing the silicon wafer in a culture dish, respectively carrying out ultrasonic treatment for 10min at room temperature by using acetone, isopropanol and water with the power of 60W, placing the silicon wafer in a hot plate at 100 ℃ after drying the silicon wafer by using nitrogen, heating for 3min, removing water vapor, cooling to room temperature, and beating for 3min by using the power of 100W of oxy gen plasma.

(2) Substrate layer poly-p-xylylene layer/insulating layer poly-p-xylylene layer:

the Parylene-C (Parylene-C) layer is prepared by a chemical vapor deposition method. The method is completed by the following three steps:

1) heating the parylene dimer raw material to a gaseous state in an evaporation cavity;

2) introducing the raw material gas obtained by sublimation into a cracking cavity to obtain an active parylene monomer;

3) the parylene monomer obtained in the second step was transferred to a room temperature vacuum deposition chamber to deposit a parylene layer on the wafer. The deposition thickness is controlled by controlling the deposition time and the gas flow of parylene monomer.

(3) Ir layer:

cleaning the sheet with the substrate poly-p-xylylene layer, preparing a layer of AZ4620 mask by using a planar photoetching method, sequentially depositing an adhesion layer metal Cr with the thickness of 50nm and a conducting layer metal Ir with the thickness of 500nm by using a thermal evaporation method or an electron beam evaporation method, finally stripping a pattern, and cleaning.

3. The rear end of the electrode is connected with:

(2) Pressing a flexible flat cable: marking alignment marks on the ten-channel flexible flat cables, cutting off proper ACF glue to cover electrode welding points, aligning the marks of the flexible flat cables with the electrode welding points, and then hot-pressing on a hot plate at 150 ℃ for 90 s.

Example 8

3D prints bearing structure

Designing a three-dimensional graph of a supporting structure on PROE three-dimensional graph design software; the dimensional parameters were as follows: the length of the support structure is 100 mm; the width of the support structure is 100 mm; the thickness of the support structure is 0.5 mm; the aperture of the support structure is 1.15 mm; saved in STL format.

Example 9

Flexible electrode array/optical fiber composite nerve electrode

The dimensions of the optical fiber used in the present invention are as follows: ferrule 10.5mm phi 1.25mm, fiber core 180mm phi 100 μm.

Assembling the optical fiber and the optical fiber support, then placing the electrode on the optical fiber support, and centering the optical fiber and the electrode left and right to enable the electrode to exceed the optical fiber by about 15 mm; and then putting the flexible electrode array/optical fiber composite nerve electrode into deionized water, vertically fishing out the flexible electrode array/optical fiber composite nerve electrode to enable the electrode to be wrapped on the surface of the optical fiber in a curling manner, then putting the flexible electrode array/optical fiber composite nerve electrode into a high-temperature melting curing material for curing treatment, and finally fixing the electrode and the supporting structure by using a copper adhesive tape.

Example 10

The nerve electrodes prepared in examples 1 to 9 were subjected to electrophysiological signal detection by the following methods:

1. preoperative preparation:

preparing gauze, electric blanket, operating table, lighting system, cranial drill, and bulb at 75% C₂H₅OH surgical instruments, absorbent cotton balls, cotton swabs, normal saline, iodophors, anesthetics and penicillin G sodium solution.

2. Preparing a solution:

and (3) anesthetic: weighing urethane according to the weight ratio of 2.6g/Kg, adding normal saline to prepare 2ml solution

3. Anesthesia:

putting the SD rat into a closed plastic box, adding 0.2ml of isoflurane by using an injector, and closing a box cover; waiting for the rat to absorb 1ml of the prepared anesthetic by using a new syringe during the transient anesthesia period; taking out the rat after the rat falls down, laying the rat with the legs upward, and quickly injecting the anesthetic into the abdominal cavity; the insertion is performed in parallel to avoid puncturing the internal organs.

4. The operation process comprises the following steps:

(1) placing the transgenic rat on an electric blanket padded with clean cloth, heating the electric blanket to a medium temperature, covering the body of the rat except the head by gauze, inserting an ear bar into a skull groove in front of an ear hole to limit the left-right swinging freedom degree of the head of the rat, opening the mouth of the rat, biting a tooth socket, screwing down a knob of the tooth socket and limiting the up-down swinging freedom degree of the head of the rat.

(2) The iodophor is used for absorbing and moistening the rat hair on the head by a cotton swab so as to prevent the hair scraps from flying in a mess during shearing, and the rat hair is sheared by a curved scissors.

(3) The exposed scalp after hair cutting is wiped with iodophor for disinfection, and the scalp is cut off by using a direct scissors, and attention should be paid to the fact that a large mouth is cut as far as possible at the moment so as to facilitate subsequent operation. If bleeding occurs, a cotton swab can be used to suck physiological saline to stop bleeding.

(4) Dropping a proper amount of H with a syringe₂O₂On the scalp, the superior membrane of the skull was wiped off with a cotton swab until a white skull was exposed.

(5) Positioning with bregma, drawing a craniotomy site mark on the skull with a black thin-head sign pen, turning on a cranial drill power switch, drilling a small rectangle of about 3 × 5mm with the mark as the center under a microscope, adding cerebrospinal fluid frequently during the skull grinding process, and erasing with a cotton swab to prevent bone fragments from filling and blocking the visual field. When the drill is drilled through, the brain should be injured carefully, and the speed should be reduced, and the user can press the drill gently with forceps to determine whether the drill has been drilled through. Finally, the skull is lifted by the syringe needle and removed by the tip forceps.

(6) The dura mater was punctured at the avascular edge with a small syringe needle and gradually torn with a sharp-tipped forceps. The brain tissue with uncovered dura mater was covered with a cotton ball moistened with saline to prevent contamination of the brain tissue.

(7) And connecting a 128 channel, connecting a laser, implanting into a brain somatosensory cortex under the assistance of a microscope and a stereotaxic apparatus, wherein the implantation depth is 200-1500 mu m, and starting recording.

(8) In the recording process, light stimulation is given every ten seconds at intervals of ten seconds, the light stimulation is 473nm laser power of 10mW, the obtained data is subjected to band-pass filtering by 250-5000 HZ, and single neuron action potentials are analyzed.

5. Conclusion of the experiment

Light stimulation can significantly and rapidly increase the firing frequency of neuron action potentials, but has little effect on firing amplitude. After the light stimulation is added, the response that the single unit signal emitting frequency is obviously increased can be obtained instantly, and after the laser is turned off, the signal emitting frequency can be recovered to the emitting level instantly when the light stimulation is not added, which shows that the response speed of the light stimulation regulation and control of the new number emission of the neuron is very high. Moreover, because a virus transfection mode can be used for leading a specific type of neuron to express the photosensitive protein, the light stimulation regulation of the neuron signal emission also has the characteristic of neuron specificity.

The applicant declares that the present invention illustrates the detailed structural features of the present invention through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must be implemented depending on the above detailed structural features. It should be understood by those skilled in the art that any modifications of the present invention, equivalent substitutions of selected components of the present invention, additions of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.

It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and the invention is not described in any way for the possible combinations in order to avoid unnecessary repetition.

In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.

Claims

1. The flexible electrode array-optical fiber composite nerve electrode is characterized by comprising a flexible electrode array, optical fibers and a supporting structure, wherein a groove is formed in the surface of the supporting structure, the optical fibers are fixed in the groove, the flexible electrode array comprises a welding spot, an interconnection lead and a recording site which are sequentially connected, the welding spot area is fixed on the surface of the supporting structure, and the interconnection lead and the recording site area are wrapped on the surface of the optical fibers in a curling mode;

the preparation method of the nerve electrode comprises the following steps:

(2) fixing one side of the flexible electrode array with the substrate silicon wafer on the surface of one side of the supporting structure provided with the groove;

(5) and putting the flexible electrode array/optical fiber composite nerve electrode into a high-temperature molten curing material for curing treatment to obtain the flexible electrode array-optical fiber composite nerve electrode.

2. The neural electrode of claim 1, wherein the flexible electrode array comprises a flexible substrate layer, a conductive layer, and a flexible insulating layer connected in series.

3. The neural electrode of claim 2, wherein the pad areas of the flexible electrode array are bonded to a base silicon wafer through a flexible backing layer.

4. The neural electrode of claim 1, wherein the pad region is attached to a silicon substrate and fixed to the surface of the support structure on the side where the recess is formed.

5. The neural electrode of claim 1, wherein the flexible electrode array is secured to a surface of the support structure on a side where the recess is provided.

6. The neural electrode of claim 2, wherein the materials of the flexible substrate layer and the flexible insulating layer each independently comprise any one of SU8 photoresist, polyimide, or parylene, or a combination of at least two thereof.

7. The neural electrode of claim 2, wherein the flexible substrate layer has a thickness of 0.5-10 μm.

8. The neural electrode of claim 7, wherein the flexible substrate layer has a thickness of 1-8 μm.

9. The neural electrode of claim 8, wherein the flexible substrate layer is 5 μm thick.

10. The neural electrode according to claim 2, wherein the thickness of the flexible insulating layer is 0.5 to 10 μm.

11. The neural electrode according to claim 10, wherein the thickness of the flexible insulating layer is 0.5 to 5 μm.

12. The neural electrode of claim 11, wherein the flexible insulating layer has a thickness of 0.5 μ ι η.

13. The neural electrode of claim 2, wherein the material of the conductive layer comprises any one of gold, platinum or iridium or a combination of at least two thereof.

14. The neural electrode according to claim 2, wherein the conductive layer has a thickness of 20 to 500 nm.

15. The neural electrode of claim 13, wherein the conductive layer has a thickness of 50 to 300 nm.

16. The neural electrode of claim 15, wherein the conductive layer has a thickness of 200 nm.

17. The neural electrode of claim 2, wherein an adhesion layer is disposed between the flexible insulating layer and the conductive layer.

18. The neural electrode of claim 17, wherein the material of the adhesion layer comprises chromium or tantalum.

19. The neural electrode of claim 17, wherein the adhesive layer has a thickness of 1 to 50 nm.

20. The neural electrode of claim 19, wherein the adhesive layer has a thickness of 3 to 15 nm.

21. The neural electrode of claim 20, wherein the adhesive layer has a thickness of 5 nm.

22. The neural electrode of claim 1, wherein the array of flexible electrodes has recording sites disposed thereon.

23. The neural electrode of claim 22, wherein the recording sites are circular in shape.

24. The neural electrode according to claim 22, wherein the number of recording sites is 1 to 800.

25. The neural electrode according to claim 24, wherein the number of recording sites is 1 to 100.

26. The neural electrode of claim 25, wherein the number of recording sites is 10.

27. The neural electrode of claim 22, wherein the recording sites have a diameter of 5-40 μm.

28. The neural electrode of claim 27, wherein the recording sites have a diameter of 10-30 μm.

29. The neural electrode of claim 28, wherein the recording sites are 10 μm in diameter.

30. The neural electrode according to claim 22, wherein when the number of recording sites is greater than 1, the pitch of the recording sites is 50 to 500 μm.

31. The neural electrode according to claim 30, wherein when the number of recording sites is greater than 1, the pitch of the recording sites is 100 to 200 μm.

32. The neural electrode of claim 31, wherein when the number of recording sites is greater than 1, the pitch of the recording sites is 150 μm.

33. The nerve electrode of claim 1, wherein the nerve electrode is prepared by a micro-nano machining method.

34. The neural electrode of claim 33, wherein the micro-nano machining method comprises sputtering a sacrificial layer, forming a substrate layer by lithography or etching, evaporating a metal conductive layer, forming an insulating layer by lithography or etching, and corroding the sacrificial layer.

35. The neural electrode according to claim 1, wherein the optical fiber has a length of 2 to 180 mm.

36. The neural electrode of claim 35, wherein the optical fiber has a length of 10-50 mm.

37. The neural electrode of claim 36, wherein the length of the optical fiber is 25 mm.

38. The neural electrode according to claim 1, wherein the optical fiber has a diameter of 100 to 400 μm.

39. The neural electrode of claim 38, wherein the optical fiber has a diameter of 100-300 μm.

40. The neural electrode of claim 39, wherein the optical fiber has a diameter of 200 μm.

41. The neural electrode according to claim 1, wherein the optical fiber has a numerical aperture of 0.22 to 0.48.

42. The neural electrode of claim 1, wherein a side of the optical fiber not covered by the flexible electrode array is provided with a sleeve.

43. The neural electrode of claim 42, wherein the cannula has a diameter of 1.25-2.50 mm.

44. The neural electrode of claim 1, wherein the support structure is formed from polylactic acid.

45. The neural electrode of claim 1, wherein the support structure has a length of 1-100 mm.

46. The neural electrode of claim 45, wherein the support structure has a length of 10-30 mm.

47. The neural electrode of claim 46, wherein the support structure is 18mm in length.

48. The neural electrode of claim 1, wherein the support structure has a width of 5-100 mm.

49. The neural electrode of claim 48, wherein the support structure has a width of 10-20 mm.

50. The neural electrode of claim 49, wherein the support structure has a width of 15 mm.

51. The neural electrode of claim 1, wherein the support structure has a thickness of 0.5mm to 5 mm.

52. The neural electrode of claim 51, wherein the support structure has a thickness of 0.8-2 mm.

53. The nerve electrode of claim 52, wherein the support structure is 1mm thick.

54. The neural electrode of claim 1, wherein the grooves in the support structure have a diameter of 1.15-2.40 mm.

55. The neural electrode of claim 1, wherein the solidifying material of step (5) is polyethylene glycol.

56. The neural electrode of claim 55, wherein said polyethylene glycol has an average molecular weight of 1000 to 8000.

57. The neural electrode of claim 56, wherein said polyethylene glycol has an average molecular weight of 1000 to 4000.

58. The neural electrode of claim 57, wherein the polyethylene glycol has an average molecular weight of 2000.

59. The nerve electrode of claim 1, wherein the flexible electrode array and the supporting structure in the flexible electrode array-optical fiber composite nerve electrode obtained in the step (5) are fixed by using a copper adhesive tape.