KR20210017127A - A large X-RAY Generator - Google Patents

Abstract

The present invention relates to a large-area X-ray generating device, capable of performing various functions, which comprises: a vacuum chamber including first and second openings on which a target and a window are seated; and an integrated electron beam emitting module inserted and withdrawn through the second opening.

Description

Large area X-ray generator {A large X-RAY Generator}

The present invention relates to a large-area X-ray generator, and more particularly, includes a vacuum chamber and an electron beam generator accommodated in the vacuum chamber, wherein the electron beam generator generates a large-area X-ray that can be easily attached and detached from the vacuum chamber. It relates to the device.

In general, X-ray generators (tubes) are widely used in various test devices or diagnostic devices such as medical diagnosis, non-destructive testing, or chemical analysis.

X-ray tubes are divided into a hot cathode method using filaments and a cold cathode method using nanostructures such as CNT (Carbon Nano Tube).

In the hot cathode method, X-rays are generated when electrons emitted from the filament collide with a target formed on the anode electrode, and in the cold cathode method, electrons emitted from a nanostructure such as CNT collide with a target formed on the anode electrode. X-rays are generated.

In the conventional hot-cathode type and cold-cathode type X-ray tube, a cathode electrode and an anode electrode on which nanostructures such as filaments or CNTs are formed are combined in an insulating case by sealing a glass tube or by ceramic brazing to maintain an internal vacuum.

However, the conventional X-ray tube is costly because only the cathode electrode cannot be replaced even if the performance of nanostructures such as filaments or CNTs that emit electrons is degraded or destroyed due to a decrease in vacuum due to gases generated inside the X-ray tube, etc. There is a problem with this increasing.

In addition, in the conventional X-ray tube, it is impossible to replace a cathode electrode on which a nanostructure such as a filament emitting electrons or a nanostructure such as CNT is formed, and thus there is a problem in that an X-ray tube has to be purchased according to the required performance of the X-ray tube.

In addition, in the conventional X-ray tube, since the area of the emitter emitting electrons is inevitably small, X-rays in the form of a point light source are irradiated, so that large-area X-rays cannot be generated, or a plurality of X-ray tubes must be arranged. However, arranging a plurality of X-ray tubes also has a problem in that non-uniformity of X-ray doses in regions where cone-beam-shaped X-rays overlap and non-overlap regions is inevitable. As a result, a decrease in the resolution of the subject may occur.

Therefore, the present invention is to take into account such a problem, it is possible to easily separate and combine the electron beam generating device from the vacuum chamber, it is possible to maintain the efficiency of the X-ray generating device, and avoided by increasing the area where X-rays are emitted from the X-ray tube. It provides a large-area X-ray generator capable of improving the resolution of a specimen.

A large-area X-ray generator according to one aspect of the present invention includes a vacuum chamber including a first opening and a second opening in which a target and a window are seated, and a large area including an integrated electron beam emission module drawn in and out through the second opening. In the X-ray generator, the integrated electron beam emission module includes a receptacle having one side connected to an external power source and the other side electrically connected to an electron beam emission device, an electron beam generation device emitting an electron beam to the target, and a cathode plate and a gate of the electron beam emitting device. Each plate is electrically connected to the receptacle, and includes a support for fixing the electron beam emitting device to the receptacle, and a coupling portion seated in the second opening.

The large-area X-ray generator may further include a turbo pump and a rotary pump to vacuum the inside of the vacuum chamber.

The large-area X-ray generator may be coupled to the target and the window to be detachably attached.

The electron beam generator of the large-area X-ray generator according to another aspect of the present invention includes a cathode plate, a CNT printed electrode substrate bonded to the cathode plate on the cathode plate, a CNT emitter formed on the CNT printed electrode substrate, the CNT printed electrode substrate and a cathode plate insulating connection portion formed to surround the CNT emitter, an insulating spacer formed on the cathode plate insulating connection portion, a gate plate insulating connection portion formed on the insulating spacer and coupled to the insulating spacer, the And a gate mesh formed on the gate plate and the gate plate and coupled to the gate insulation connection part above the gate plate insulation connection part.

The gate plate includes a first region extending in a horizontal direction from an upper portion of the gate plate insulating connection part and a second region extending vertically from the first region in a direction of the cathode plate, and the second region is insulated from the gate plate. A connection part, the insulating spacer, and the cathode plate are formed inside the insulating connection part, and the second region extends to a length covering at least a part of the insulation connection part of the cathode plate including the gate insulation connection part and the insulation spacer, and the second The area may be formed to have a larger area than that of the CNT printed electrode substrate.

The cathode plate may have a receiving groove capable of accommodating the CNT printed electrode substrate.

According to such a large-area X-ray generator, since the electron beam generator is coupled so that it is possible to draw in and out of the vacuum chamber as needed, the electron beam generator is deteriorated when the life of the electron beam generator is over or a problem occurs in the electron beam generator. Since only the generator can be newly replaced, it is possible to prevent performance degradation of the large-area X-ray generator.

In addition, since the area of the CNT emitter, the area of the target, and the window are formed wide, X-rays are emitted in a wide area from the X-ray generator, so that the resolution is improved when the subject is inspected.

In addition, since the target and the window are combined to be detachable from the vacuum chamber, the target and window can be replaced with a new target and window when the lifespan of the target and window is over or when the target and window are degraded due to problems, large-area X-rays are generated. Device performance degradation can be prevented.

In addition, various functions can be performed by attaching and attaching various types of targets and windows, that is, targets and windows for generating X-rays, fluorescent plates and windows for emitting light, and thin films and windows for emitting electrons, in the vacuum chamber. have.

1 is a cross-sectional view of a large area X-ray generator according to an embodiment of the present invention.
2 is a block diagram of a vacuum chamber and a pump according to an embodiment of the present invention.
3 and 4 are an integrated electron beam emission module formed to be freely withdrawn from a vacuum chamber according to an embodiment of the present invention, and are views showing a connection structure of a receptacle, an electron beam emission device, a support and a coupling part.
5 and 6 are cross-sectional views of an electron beam emitting device according to an embodiment of the present invention.

The features and effects of the present invention described above will become more apparent through the following detailed description in connection with the accompanying drawings, and accordingly, those of ordinary skill in the art to which the present invention pertains can easily implement the technical idea of the present invention. I will be able to. In the present invention, various modifications may be made and various forms may be applied, and specific embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific form disclosed, it should be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the present invention. The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present application, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, actions, components, parts, or a combination thereof described in the specification, but one or more other features or It is to be understood that the presence or addition of numbers, steps, actions, components, parts, or combinations thereof does not preclude the possibility of preliminary exclusion. Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. These terms are only used for the purpose of distinguishing one component from another component. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may be referred to as a first component. In addition, in the present application, expressions including top and bottom, such as top, bottom, top, and bottom, are not classified according to absolute height, but represent a relative position centered on the internal space of the device.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

1 is a cross-sectional view of a large area X-ray generator according to an embodiment of the present invention, FIG. 2 is a configuration diagram of a vacuum chamber and a pump according to an embodiment of the present invention, and FIGS. 3 and 4 are an embodiment of the present invention. An integrated electron beam emission module formed to facilitate freely withdrawal from a vacuum chamber according to an embodiment, and is a view showing a connection structure of a receptacle, an electron beam emission device, a support and a coupling part, and FIGS. 5 and 6 are an embodiment of the present invention. Is a cross-sectional view of the electron beam emission device according to.

Referring to FIG. 1, a large-area X-ray generator 1000 according to an embodiment of the present invention includes a vacuum chamber 100, a receptacle 200 capable of being drawn in and out of the vacuum chamber 100, and an electron beam generating an electron beam. The apparatus 300, the support 400 for electrically connecting the electron beam generating device 300 to the receptacle 200 and fixing and supporting the electron beam generating device 300 to the receptacle 200 so that the electron beam generating device 300 does not move, and the vacuum chamber 100 It includes a turbo pump 500 and a rotary pump 600 to maintain the interior in a vacuum.

Referring to FIGS. 1 and 2, the vacuum chamber 100 maintains a vacuum state inside the turbo pump 500 and the rotary pump 600. When the inside of the vacuum chamber 100 does not satisfy the vacuum condition, the turbo pump 500 and the rotary pump 600 are driven to maintain the inside of the vacuum chamber 100 in a vacuum.

The vacuum chamber 100 includes a first opening 110, a target and a window 120, and a second opening 130.

The first opening 110 is formed to be positioned above the electron beam generating device 300 in a state in which the electron beam generating device 300 is seated in the vacuum chamber 100 as shown in FIG. 1, and the first opening 110 ), the target and the window 120 are combined.

The target and the window 120 may be coupled to the first opening 110 by brazing, or may be fitted to the first opening 120 to facilitate attachment or detachment, or may be coupled by a fastening member such as a bolt, nut, or screw. .

When the target and the window 120 are fitted to the first opening 110 for easy attachment and detachment, and are coupled by fastening members such as bolts, nuts, and screws, among the target and the window 120 and the first opening 110 Sealing members such as a gasket and an O-ring are formed in at least one to seal the inside of the vacuum chamber 100, prevent foreign matter such as air and moisture from entering into the vacuum chamber 100 from the outside, and an electron beam generator ( It is desirable to prevent the electron beam emitted from 300) from leaking to the outside. Since the target and the window 120 are detachably coupled to the first opening 110, the target and the window 120 can be replaced when the lifespan of the target is over and the X-ray generation efficiency decreases, or when a defect occurs in the target and/or window, the vacuum chamber 100 ) It is possible to reduce costs by not replacing the whole.

The target and the window 120 generate X-rays from the electron beam emitted from the electron beam generator 300 and emit them to the outside of the vacuum chamber 100. In more detail, the target collides with the electron beam emitted from the electron beam generator 300 to generate X-rays, and the window serves to emit the X-rays generated by the collision with the target to the outside of the vacuum chamber 100.

The area of the target and the window 120 is equal to or larger than the area of the electron beam emitting device 300. Conventionally, the area of the target and the window is formed to be narrow so that X-rays are emitted in a narrow area, and the emitted X-rays spread widely and reach the subject, resulting in a decrease in resolution. Since X-rays are emitted in a wide area from the start, the resolution can be improved because the X-rays reach the subject before the X-rays spread widely. In addition to such an X-ray image, static electricity removal using X-rays may be applied to a large area, and thus may be used in various X-ray applications.

The target and the window 120 have a transmissive structure in which a tungsten (W) target is directly coated on a lower surface of a beryllium (Be) window.

The target and the window 120 are not limited to the transmissive structure described above, but may be formed in a reflective structure in which the target and the window are separately formed. For example, an anode electrode having a target formed thereon may be coupled to the first opening 110 of the vacuum chamber 100, and a window may be coupled to another portion of the vacuum chamber 100. The target coupled to the first opening 110 collides with the electron beam emitted from the electron beam generator 300 to generate X-rays, and the window coupled to the other part of the vacuum chamber 100 is generated by collision with the target. , X-rays reflected by the target are emitted to the outside of the vacuum chamber 100. The position at which the window is coupled to the vacuum chamber 100 is formed in a path through which the electron beam collides with the target and is reflected so that X-rays can be emitted outside the vacuum chamber 100.

Although the target and the window 120 coated with tungsten on the lower surface of the beryllium window to generate X-rays have been described above, various types of targets and windows 120 may be coupled to the vacuum chamber 100. For example, a light emitting plate coated with a phosphor and a window may be combined on a lower surface of a transparent window such as glass, and electrons emitted from the electron beam generator 300 may be used as a lamp to emit light by colliding with the phosphor target, and an aluminum thin film window Electrons that are coupled and emitted from the electron beam generator 300 are directly emitted to the outside through a window, and may be used for surface treatment of a sample such as a semiconductor, or may be used for sterilizing food.

The second opening 130 is formed on one surface of the vacuum chamber 100, and through the second opening 130, an integrated electron beam emission module including a receptacle, an electron beam emission device, a support and a coupling unit can be withdrawn as necessary. To be formed.

The coupling part is fitted into the vacuum chamber so that the integrated electron beam emission module can be drawn in and out, and is coupled by fastening members such as bolts, nuts, screws, etc., and forming sealing members such as gaskets and O-rings to allow the vacuum chamber 100 to It is preferable to keep the inside completely sealed, prevent foreign matters such as air and moisture from entering into the vacuum chamber 100 from the outside, and prevent the electron beam emitted from the electron beam generator 300 from leaking to the outside.

1 and 3, the receptacle 200 is connected to the electron beam generating device 300 through the support 400, and the receptacle 200 connected to the electron beam generating device 300 is vacuum through the connection part 220. It is combined with the chamber 100.

The receptacle 200 is connected to an external terminal part 210 connected to an external power source (not shown), a coupling part 220 connected to the vacuum chamber 100, a support 400, and internally connected to the external terminal part 210 It includes an internal terminal unit 230 capable of applying external power to the support 400.

The external terminal unit 210 includes one or more external terminals (not shown), and the one or more external terminals are connected to an external power source through a power cable or the like to apply power to the large-area X-ray generator 1000.

The coupling part 220 seals the vacuum chamber 100 while introducing the integrated electron beam emission module into the vacuum chamber 100. The coupling part 220 can be sealed in various ways. For example, the receptacle 200 may be coupled to the vacuum chamber 100 by forming a thread in the coupling portion 220 and the second opening 130, or the coupling portion 220 may be prevented from the second opening 130 The receptacle 200 may be coupled to the vacuum chamber 100 by fitting in a fitting manner, and the coupling portion 220 and the second opening 130 may be coupled with a fastening member such as screws or bolts. The method of coupling the coupling part 220 and the second opening 130 is not limited to the method described above, and any method may be used as long as it is a method capable of coupling and fixing the receptacle 200 to the vacuum chamber 100. .

When the coupling part 220 is coupled to the second opening 130 of the vacuum chamber 100, the vacuum inside the vacuum chamber 100 is maintained, and foreign substances such as air and moisture enter the vacuum chamber 100. In order to prevent the electron beam emitted from the electron beam emission device 300 from being emitted to the outside of the vacuum chamber 100, a sealing member such as a gasket and an O-ring is provided in at least one of the coupling part 220 and the second opening 130 Can be formed.

The internal terminal unit 230 is connected to the external terminal unit 210 inside the receptacle 200 to be connected to an external power source.

The inner terminal unit 230 includes a first inner terminal 232 and a second inner terminal 234, and the first inner terminal 232 is coupled to the first support 410 and passes through the first support 410. External power is applied to the electron beam generating device 300, and the second internal terminal 234 is coupled to the second support 420 to apply external power to the electron beam generating device 300 through the second support 420. .

1, 3, 4, and 5, the support 400 electrically connects the receptacle 200 and the electron beam generator 300, and the receptacle 200 so that the electron beam generator 300 does not move. ) Serves to fix and support the electron beam generator 300.

The support 400 includes a first support 410 and a second support 420, and the first support 410 is a first internal terminal 232 of the receptacle 200 and a cathode of the electron beam generator 300 The plate 310 is electrically connected to apply external power to the cathode plate 310, and the second support 420 is a second inner terminal 234 of the receptacle 200 and a gate plate of the electron beam generator 300 External power is applied to the gate plate 370 by electrically connecting the 370.

The first support 410 and the second support 420 not only electrically connect the receptacle 200 and the electron beam generating device 300, but also fix and support the electron beam generating device 300 to the receptacle 200 so as not to move. Play a role. The first support 410 and the second support 420 are formed of a material having high strength so that the electron beam generating device 300 is connected to the receptacle 200 and does not move, that is, does not bend. From the front, the material of the first support 410 and the second support 420 may apply external power to the electron beam generator 300 from the receptacle 200 connected to the external power source, and the electron beam generator 300 is bent. It can be formed of any material as long as it can be fixed and supported. When the electron beam generator 300 is fixed and supported by the support 400, when the large-area X-ray tube 1000 is driven, the electron beam is accurately emitted to the target and the window 120, thereby improving X-ray emission efficiency.

1, 3, 5, and 6, the electron beam generator 300 generates an electron beam by receiving external power through the receptacle 200 and the support 400.

The electron beam generator 300 includes a cathode plate 310, a carbon nano tube (CNT) printed electrode substrate 320, a CNT emitter 330, a cathode plate insulation connection 340, an insulation spacer 350, and a gate plate insulation. A connection part 360, a gate plate 370, and a gate mesh 380 are included.

The cathode plate 310 is located above the first support 410 and is connected to the first support 410 to apply external power. When the cathode plate 310 is coupled to the upper portion of the first support 410, the electron beam emitting device 300 is firmly fixed and supported by the receptacle 200. The method of combining the cathode plate 310 and the first support 410 is not limited to the method described above, and may be combined in various ways. For example, the side portion of the cathode plate 310 and the side portion of the first support 410 may be coupled with a fastening member such as screws or bolts.

As shown in FIG. 6, the cathode plate 310 may have a receiving groove formed in the center so that the CNT printed electrode substrate 320 is inserted therein. The receiving groove may not be formed according to the operator's choice. When the receiving groove is not formed, the CNT printed electrode substrate 320 is coupled to the upper portion of the cathode plate 310. The cathode plate 310 and the CNT printed electrode substrate 320 may be combined by various methods. For example, the cathode plate 310 and the CNT printed electrode substrate 320 may be coupled by an adhesive, or may be coupled by bolts or screws. The combination of the cathode plate 310 and the CNT printed electrode substrate 320 may use any method as long as it is a method capable of fixing the CNT printed electrode substrate 320 to the cathode plate 310 in addition to the method described above.

The CNT printed electrode substrate 320 is coupled to the upper portion of the cathode plate 310, and a CNT emitter 330 is formed on the upper portion of the CNT printed electrode substrate 320. The CNT emitter 330 formed on the CNT printed electrode substrate 320 may be formed in a pattern shape in a partial region of the CNT printed electrode substrate 320, or bulk ( It can also be formed in a bulk) shape. Since the method of forming the CNT emitter 330 is the same as the method of forming the conventional CNT emitter, a detailed description will be omitted.

The cathode plate insulating connection part 340 is formed on the cathode plate 310 and is formed to surround the CNT printed electrode substrate 320 and the CNT emitter 330. It is preferable that the height of the insulating connection portion 340 of the cathode plate is formed higher than the end of the CNT emitter 330 in order to prevent electrons emitted from the CNT emitter 330 from leaking to the outside, thereby improving electron emission efficiency.

The cathode plate insulating connection part 340 may be formed separately from the cathode plate 310 and combined, or may be integrally formed through injection molding or the like. The cathode plate 310 and the cathode plate insulating connection part 340 may be coupled by various methods such as bonding, bolts, screws, or other fastening members, or brazing.

The insulating spacer 350 is formed between the upper portion of the cathode plate insulating connection part 340 and the lower portion of the gate plate insulating connection part 360 to insulate the cathode plate insulating connection part 340 and the gate plate insulating connection part 360. Since the cathode plate insulation connection part 340 and the gate plate insulation connection part 360 are insulated through the insulation spacer 350, the cathode plate 310 and the second support 420 to which external power is applied through the first support 410. ), the gate plate 370 to which external power is applied is insulated.

The insulating spacer 350 is formed of an insulating material such as ceramic, and the insulating spacer 350 may be formed on the entire area of the insulating connection part 340 of the cathode plate, or only a partial area of the insulating connection part 340 of the cathode plate. May be. The insulating spacer 350 is to insulate between the cathode plate insulating connection part 340 and the gate plate insulating connection part 360, and is formed only in some areas to insulate the cathode plate insulating connection part 340 and the gate plate insulating connection part 360 It is preferable in terms of cost reduction and the like.

The insulating spacer 350 is coupled to the cathode insulating connection part 340 and the gate plate insulating connection part 360. The existing spacer 350 may be coupled to the cathode plate insulation connection part 340 and the gate plate insulation connection part 360 through a fastening member such as a force fitting, a bolt screw, or a brazing method.

The gate plate insulating connection part 360 is formed on the insulating spacer 350 and is coupled to the insulating spacer 350.

The gate plate 370 is formed on the gate plate insulating connection part 360, and is coupled to the gate plate insulating connection part 360 through a fastening member such as bonding, bolts, screws, or brazing.

The gate plate 370 includes a first region extending horizontally and coupled to an upper portion of the gate plate insulating connection part 360 and a second region extending vertically to the first region. That is, the gate plate 370 is formed in a'L' shape. In this case, the second region is formed inside the gate plate insulating connection part 360, the insulating spacer 350, and the cathode plate insulating connection 340, and the second region is formed wider than the CNT emitter substrate 320.

The second region of the gate plate 370 extends to a length covering at least a portion of the gate plate insulating connection part 360 and the insulating spacer 350 as well as the cathode plate insulating connection part 340, and is wider than the CNT printed electrode substrate 320. Electrons formed in an area and emitted from the CNT emitter 330 can be effectively prevented from being emitted to the outside through the insulating spacers 350 formed only in a partial area above the insulating connection part 340 of the cathode plate.

The gate mesh 380 is formed at the end of the second station area of the gate plate 370. The gate mesh 380 is formed at a position in which a plurality of gate holes (not shown) are formed, and the plurality of gate holes are formed in a position aligned with the pattern in which the CNT emitter 330 formed on the CNT printed electrode substrate 320 is formed. do. As the plurality of gate holes formed in the gate mesh 380 and the CNT emitter 330 formed on the CNT printed electrode substrate 320 are aligned, electrons emitted from the CNT emitter do not collide with other places, and are directly gate holes. As the amount of electrons passing through is increased, the efficiency of emitted electrons can be improved.

In the detailed description of the present invention described above, it has been described with reference to preferred embodiments of the present invention, but those skilled in the art or those of ordinary skill in the art will have the spirit of the present invention described in the claims to be described later. And it will be appreciated that various modifications and changes can be made to the present invention within a range not departing from the technical field.

1000: large area X-ray tube 100: vacuum chamber
110: first opening 120: target and window
130: second opening 200: receptacle
210: external terminal part 220: coupling part
230: internal terminal part 232: first internal terminal
234: second internal terminal 300: electron beam generator
310: cathode plate 320: CNT printed electrode substrate
330: CNT emitter 340: cathode plate insulation connection
350: insulation spacer 360: gate plate insulation connection
370: gate plate 380: gate mesh
400: support 410: first support
420: second support 500: turbo pump
600: rotary pump

Claims (6)

A vacuum chamber including a first opening and a second opening in which the target and the window are seated;
In the large-area X-ray generator comprising an integrated electron beam emission module that is drawn in and out through the second opening,
The integrated electron beam emission module
A receptacle having one side connected to an external power source and the other side being electrically connected to an electron beam emission device;
An electron beam generator for emitting an electron beam to the target;
A support for fixing the electron beam emitting device to the receptacle while electrically connecting the cathode plate and the gate plate of the electron beam emitting device to the receptacle, respectively; And
A large-area X-ray generator comprising: a coupling portion seated in the second opening. The method of claim 1,
A large-area X-ray generator further comprising a turbo pump and a rotary pump for making the inside of the vacuum chamber vacuum. The method of claim 1,
The target and the window are large-area X-ray generating apparatus, characterized in that the detachably coupled. The method of claim 1,
The electron beam generating device,
Insulation of a cathode plate, a CNT printed electrode substrate coupled to the cathode plate on the cathode plate, a CNT emitter formed on the CNT printed electrode substrate, and a cathode plate formed to surround the CNT printed electrode substrate and the CNT emitter A connection part, an insulating spacer formed on the cathode plate insulating connection part, a gate plate insulating connection part formed on the insulating spacer and coupled to the insulating spacer, the gate insulating connection part and the gate insulating connection part on the gate plate insulating connection part, and the gate plate and A large-area X-ray generator comprising a gate mesh formed on the gate plate. The method of claim 4,
The gate plate includes a first region extending in a horizontal direction from an upper portion of the gate plate insulating connection part and a second region extending vertically from the first region in a direction of the cathode plate,
The second region is formed inside the gate plate insulating connection part, the insulating spacer, and the cathode plate insulating connection part, and the second region includes the gate insulating connection part and the insulating spacer, and includes at least a portion of the cathode plate insulating connection part. A large area X-ray generator, characterized in that it extends to a covering length, and wherein the second area is formed to have a larger area than an area of the CNT printed electrode substrate. The method of claim 4,
The cathode plate is a large area X-ray generating apparatus, characterized in that the receiving groove is formed to accommodate the CNT printed electrode substrate.

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