Bolometer and its manufacturing method

Abstract

To provide a bolometer having a high TCR value and a low resistance, and a method for manufacturing the same.SOLUTION: There is provided a bolometer manufacturing method which includes the steps of: fabricating a set of two carbon nanotube wires that are approximately parallel to each other at edges of a line shape, or fabricating a circular shape carbon nanotube wire at a circular circumference of a circular shape, by applying a semiconducting carbon nanotube dispersion liquid in the line shape or the circular shape on a substrate, and drying the dispersion liquid, a line width of each wire being 5 μm or more; and connecting a part of each wire to a first electrode and a second electrode.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a bolometer using carbon nanotubes and a method for manufacturing the same. [Background technology]

[0002] Quantum infrared sensors made of HgCdTe have been widely used as infrared sensors, but they require the element to be cooled to a temperature below liquid nitrogen, which limits the miniaturization of the equipment.In recent years, therefore, uncooled infrared sensors, which do not require the element to be cooled to low temperatures, have attracted attention, and bolometers, which detect changes in electrical resistance due to changes in the element's temperature, have become widely used. The temperature coefficient of resistance (TCR) and resistivity are particularly important performance factors for a bolometer. As the absolute value of TCR increases, the temperature resolution of the infrared sensor decreases and its sensitivity improves. Furthermore, resistivity must be reduced to reduce noise. Conventionally, vanadium oxide thin films have been used as uncooled bolometers, but because their TCR is small (approximately -2.0% / K), improvements to the TCR have been widely studied. To improve the TCR, it is necessary for the material to have semiconducting properties and a large band gap, and it is expected that semiconducting single-walled carbon nanotubes will be used as bolometers. Patent document 1 proposes the fabrication of a bolometer using a thin-film process in which ordinary single-walled carbon nanotubes are used in the bolometer section, a dispersion of single-walled carbon nanotubes mixed in an organic solvent is cast onto an electrode, and the single-walled carbon nanotubes are annealed in air. Patent Document 2 proposes the production of a bolometer in which, since single-walled carbon nanotubes contain a mixture of metallic and semiconducting components, semiconducting single-walled carbon nanotubes are extracted using an ionic surfactant and applied to the bolometer section. Furthermore, Patent Document 3 proposes a method of producing a transparent conductive film by forming two thin conductive wires from a line-shaped liquid of a conductive material by the coffee stain phenomenon, and then removing one of the wires. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] WO2012 / 049801 issue [Patent Document 2] Patent No. 6455910 [Patent Document 3] Patent No. 6717316 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the carbon nanotube thin film used in the infrared sensor described in Patent Document 1 has a low TCR due to the presence of metallic carbon nanotubes mixed with the carbon nanotubes, limiting the improvement of the infrared sensor's performance. The infrared sensor using semiconducting carbon nanotubes described in Patent Document 2 has the problem that the ionic surfactant used for separation cannot be easily removed. The functional thin wire described in Patent Document 3 is a thin wire made of conductive fine particles used in transparent conductive films, and has the problem that a process is required to remove one of the two wires. Semiconducting materials are suitable for use in infrared sensors, and low resistance is desirable, so the thin wire needs to be thicker.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a bolometer having a high TCR value and low resistance, and a method for manufacturing the same. Another aspect of the present invention is to provide a method for manufacturing a minute semiconducting carbon nanotube thin wire by a simple method. [Means for solving the problem]

[0006] The present invention solves the above problems and has the following features.

[0007] One aspect of the present invention is A step of applying a semiconducting carbon nanotube dispersion liquid in a line shape or a circle shape on a substrate and drying the dispersion liquid to produce a pair of substantially parallel carbon nanotube thin wires on the edge of the line shape or a circular carbon nanotube thin wire on the circumference of a circle shape, wherein the line width of the thin wires is 5 μm or more; The present invention relates to a method for manufacturing a bolometer, which includes a step of connecting a part of the thin wire to a first electrode and a second electrode. [Effects of the Invention]

[0008] According to the invention of this application, it is possible to provide a bolometer having a high TCR value and low resistance, and a method for manufacturing the same.

[0009] Furthermore, according to one aspect of the present invention, the carbon nanotube layer can be made smaller by a simple method, and therefore the bolometer element can be made smaller.

[0010] Furthermore, the manufacturing method according to one embodiment of the present invention is low cost and suitable for mass production. [Brief explanation of the drawings]

[0011] [Figure 1] Cross-sectional schematic diagram of the bolometer section [Figure 2] SEM image of the edge of the line shape [Figure 3] Schematic diagram of carbon nanotube dispersion patterned into two lines on a substrate [Figure 4] An example of arranging two edges of a line shape on different electrode rows (top) and an example of creating an array with a line shape (bottom) [Figure 5] Example of removing unnecessary CNTs by applying PMMA to the electrode part of a line-shaped array [Figure 6] Example of circular dots arranged in an electrode array [Figure 7] An example of circular, opposing arcs arranged on different electrode rows [Figure 8] An example of a circular array [Figure 9] An example of a circular arc with different electrode rows arranged in between. [Figure 10] An example of a circular array with three electrode rows [Figure 11] An example of a circular array with three electrode rows DETAILED DESCRIPTION OF THE INVENTION

[0012] The invention of this application has the above-mentioned characteristics, and the following embodiments will be described. However, although the embodiments described below have technically preferable limitations for carrying out the invention, they do not limit the scope of the invention to the following.

[0013] By applying (patterning) a carbon nanotube dispersion onto a substrate in lines or dots (circles) and drying, the carbon nanotubes can be deposited on the edges of the lines or dots by utilizing the capillary phenomenon that occurs in the droplets of the dispersion. This allows for the production of a pair of approximately parallel carbon nanotube thin wires on the edges of the lines, or a circular carbon nanotube thin wire on the edges of the dots (circumference of the circular dots). The carbon nanotube thin wires produced in this way are connected to a first electrode and a second electrode to form a bolometer electrode. In this way, in the bolometer manufacturing method of this embodiment, by forming droplets of carbon nanotube dispersion liquid into the desired pattern shape, carbon nanotube wires of the desired shape and size can be easily formed on the substrate.

[0014] Furthermore, in one embodiment, a bolometer can be manufactured at once from one line or row of dot droplets, in which carbon nanotubes are arranged approximately perpendicular to two or more rows of electrode pairs. Specifically, a linear thin wire formed from one row of linear dispersion droplets, or a circular thin wire formed from one row of circular dispersion droplets, is connected to two or more rows of electrode pairs. Here, the carbon nanotube thin wires are connected approximately perpendicular to each electrode pair constituting the electrode pair row (i.e., approximately parallel to the current flowing between the electrode pairs).

[0015] In one embodiment, it is preferable to form an intermediate layer on the surface of the substrate, which has the function of enhancing the bonding between the substrate and the carbon nanotubes. Such an intermediate layer is preferably formed over an area wider than the area where the droplets of the carbon nanotube dispersion are formed, and the intermediate layer may be formed over the entire surface of the substrate.

[0016] In the following embodiment, an APTES layer or a polylysine layer is used as the intermediate layer, and a Si substrate or a plastic substrate is used as the substrate, but the intermediate layer and the substrate are not limited to these.

[0017] Furthermore, in the method for manufacturing a bolometer, processes other than the process of forming a carbon nanotube layer on a substrate are not limited to those exemplified below, and any process used in the technical field can be used without any particular restrictions.

[0018] In this specification, the term "substantially perpendicular" includes both completely perpendicular and a deviation from completely perpendicular of 30° or less, preferably 20° or less, for example, 10° or less. The term "substantially parallel" includes both completely parallel and a deviation from completely parallel of 30° or less, preferably 20° or less, for example, 10° or less. Furthermore, "substantially perpendicular" and "substantially parallel" include not only cases where the side intersecting the object (e.g., electrode) is a straight line, but also cases where it is part of an arc, and in this case, it is preferable that the tangent to the arc is within the above range. In this specification, the term "carbon nanotube thin wire" refers to thin carbon nanotubes and may also be referred to as a "carbon nanotube layer", etc. The term "carbon nanotube thin wire" can refer to either a network-state carbon nanotube thin wire or a thin, oriented carbon nanotube film in which carbon nanotubes are aligned in a certain direction. Furthermore, the "APTES layer" may be written as an "APTES film" or the like. Furthermore, the bolometer according to this embodiment can be used to detect not only infrared light but also electromagnetic waves having wavelengths of 0.7 μm to 1 mm, such as terahertz waves. In one embodiment, the bolometer is an infrared sensor. Furthermore, the bolometer manufacturing method according to this embodiment can be suitably applied to the manufacture of a bolometer array.

[0019] First Embodiment FIG. 1 shows a cross-sectional schematic diagram of a bolometer unit according to one embodiment of the present invention. A 3-aminopropyltriethoxysilane (APTES) layer 2 is disposed on a Si substrate 1. A carbon nanotube layer 3, a first electrode 4, and a second electrode 5 are disposed on the APTES layer 2, with the electrodes 4 and 5 connected by the carbon nanotube layer 3 between them. The arrangement of the APTES layer 2, the carbon nanotube layer 3, and the electrodes 4 and 5 on the substrate 1 is not limited to that shown in FIG. 1 . The first electrode 4 and the second electrode 5 may be disposed on the APTES layer 2 or directly on the Si substrate 1. Furthermore, the carbon nanotube layer 3 may be disposed either below or above both electrodes, as long as a portion of the carbon nanotube layer 3 is on the APTES layer 2 and is connected to the first electrode 4 and the second electrode 5. As described below, the carbon nanotube layer 3 is primarily composed of a plurality of semiconducting carbon nanotubes, preferably separated using a nonionic surfactant.

[0020] The SiO2-coated Si substrate is washed sequentially with acetone, isopropyl alcohol, and water, followed by oxygen plasma treatment to remove surface organic matter. The substrate is then immersed in an APTES aqueous solution, or alternatively, sprayed with the APTES aqueous solution, rinsed with water, and dried. As shown in Figure 3, a semiconducting carbon nanotube dispersion (2) dispersed in an aqueous solution of a polyoxyethylene alkyl ether, such as polyoxyethylene (100) stearyl ether or polyoxyethylene (23) lauryl ether, a nonionic surfactant, is applied to the APTES layer in the form of a line. The substrate is then placed under conditions that allow the dispersion solvent to evaporate. Because the evaporation rate near the outer edge of the droplet is faster than near the center, the water in the dispersion gradually dries from the line-shaped edge. The line-shaped edge pins the droplet's contact line, generating a capillary flow within the droplet toward the edge. The carbon nanotubes then migrate outward from the center of the droplet, accumulating near the edges (2a and 2a') and oriented approximately parallel to the edges. This allows for the formation of an oriented film of carbon nanotubes on both edges of the linear shape. The degree of orientation of the carbon nanotubes can be controlled by adjusting the diameter and length of the carbon nanotubes, the concentration of the surfactant, the drying speed, etc., and by adjusting these, it is possible to obtain a linear accumulation of carbon nanotubes in a network state where they are barely oriented.

[0021] Methods for applying the carbon nanotube dispersion onto the substrate in a desired shape include a dispenser, an inkjet printer, a printer, etc. The amount of droplets can be appropriately adjusted within a range that allows the desired droplet shape to be maintained and allows capillary action to occur within the droplets.

[0022] The water contact angle between the substrate and the droplet can be greater than 0° and less than 90°, but is preferably greater than 0° and less than 60°. The water contact angle is determined using the static method specified in JIS R3257;1999. The water contact angle of the droplet can be controlled by the amount of droplet relative to the area of ​​the carbon nanotube dispersion coating (line shape).

[0023] The width of the line shape of the dispersion liquid (width a in FIG. 3) is desirably 20 μm to 1 cm, preferably 20 μm to 1 mm, and more preferably 30 μm to 500 μm.

[0024] The carbon nanotubes are deposited near the edge of the dispersion coating. The width of the deposition can be varied, for example, by the amount of dispersion, the type and concentration of carbon nanotubes in the dispersion, the type and concentration of surfactant, the diameter and length of the carbon nanotubes, the substrate temperature, the relative humidity, etc. A carbon nanotube deposition layer of 5 μm to 30 μm wide from the edge is desirable, and a width of 7 μm to 20 μm is more preferable. Since the carbon nanotubes used are semiconducting, the width is preferably 5 μm or more, more preferably 7 μm or more, to reduce resistance. Furthermore, from the perspective of miniaturization, a width of 30 μm or less, preferably 20 μm or less, is desirable. The deposition width (width of the carbon nanotube film) can be the average value of measurements taken at any 10 points using a scanning electron microscope or the like.

[0025] The thickness of the carbon nanotube layer is not particularly limited, but is preferably, for example, 5 nm or more, more preferably 10 nm or more, for example, 20 nm or more, and even more preferably 30 nm or more within a range of 10 μm from the edge of the line shape, and is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 1 μm or less. The thickness of the carbon nanotubes can be measured using a laser microscope at any 10 points within a range of 10 μm from the edge, and the average value thereof can be used.

[0026] In the manufacturing method according to this embodiment, when carbon nanotubes are deposited near the edge of the dispersion coating, the carbon nanotubes can also be aligned. FIG. 2 is a scanning electron microscope (SEM) image taken at a position a few μm toward the center of the dispersion coating (the edge of the dispersion coating is on the upper side of the image). As shown in FIG. 2, the carbon nanotubes can be deposited aligned substantially parallel to the edge of the dispersion coating. Furthermore, the carbon nanotubes can be partially aligned, or can be deposited in a network state without being aligned. The degree of orientation of carbon nanotubes can be controlled by adjusting conditions such as the diameter and length of the carbon nanotubes, the concentration of the surfactant, and the drying rate. To increase the degree of orientation, it is desirable to evaporate the dispersion solvent at a slow rate, and the substrate temperature during evaporation of the dispersion solvent is desirably, for example, 5°C to 60°C, and preferably 10°C to 40°C. The relative humidity is preferably 15%RH to 80%RH. The degree of orientation of carbon nanotubes was measured by a frequency of -1 μm from the center in a plane FFT image, which was obtained by two-dimensional fast Fourier transform of an SEM image of a carbon nanotube film and expressing the distribution of unevenness in each direction as a frequency distribution. -1 +1μm from -1 The integrated value f of the amplitude up to the FFT image is calculated, and the integrated value in the direction x where the integrated value f is maximum is defined as fx, and the integrated value in the direction y perpendicular to the direction x is defined as fy. When fx / fy≧2, the carbon nanotubes are defined as being aligned. The production method according to this embodiment can also produce a carbon nanotube thin wire in which the carbon nanotubes are not aligned (or have a low degree of alignment), in which fx / fy=1 to 2. However, by controlling the above-mentioned production conditions, it is also possible to produce an aligned carbon nanotube thin wire in which fx / fy≧2. Note that the SEM image on which the FFT image is based needs to show irregularities for calculation by Fourier transform, and from the viewpoint of observing the carbon nanotubes, the field of view is preferably about 0.05 to 10 μm in both length and width.

[0027] The carbon nanotubes contain semiconducting carbon nanotubes in a proportion of preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 98% by mass or more of the total amount of carbon nanotubes. In producing such a carbon nanotube layer, it is desirable to use a dispersion liquid with a high concentration of semiconducting carbon nanotubes obtained by separating metallic carbon nanotubes and semiconducting carbon nanotubes using, for example, an electric field induced layer formation method. The diameter of the carbon nanotubes is desirably 0.6 to 1.5 nm, preferably 0.6 to 1.2 nm, and more preferably 0.6 to 1.0 nm. The length of the carbon nanotubes is desirably within the range of 100 nm to 5 μm, as this facilitates dispersion and droplet formation. From the viewpoint of the conductivity of the carbon nanotubes, the length is preferably 100 nm or more, and from the viewpoint of preventing aggregation, the length is preferably 5 μm or less. More preferably, it is within the range of 500 nm to 3 μm, and even more preferably, 700 nm to 1.5 μm. It is preferable that 70% or more (by number) of the carbon nanotubes have a diameter and length within the above ranges.

[0028] When the diameter and length of the carbon nanotube are within the above ranges, the semiconducting effect is greater when semiconducting carbon nanotubes are used, and a large current value can be obtained, so that a high TCR value is likely to be obtained when used in a bolometer.

[0029] The APTES solution and carbon nanotube dispersion liquid that can be used in the production method according to this embodiment will be described. The concentration of the APTES solution is not particularly limited, but is preferably 0.001% by volume to 30% by volume, more preferably 0.01% by volume to 10% by volume, and even more preferably 0.05% by volume to 5% by volume. The solvent for APTES is not particularly limited, as long as it is water or a solvent that can dissolve the compound and can be easily removed after application to a substrate. When a compound other than APTES is used for the intermediate layer as described below, these concentrations and solvents may be appropriately changed depending on the compound used.

[0030] The carbon nanotube dispersion liquid used in the manufacturing method of this embodiment will be described below.

[0031] The carbon nanotube dispersion contains the above-mentioned carbon nanotubes. The concentration of the carbon nanotubes in the dispersion and the amount of droplets can be appropriately selected depending on the density and thickness of the carbon nanotube layer to be formed. Although not particularly limited, the concentration of the carbon nanotubes in the dispersion can be, for example, 0.0003% by mass or more, preferably 0.001% by mass or more, more preferably 0.003% by mass or more, and 10% by mass or less, preferably 3% by mass or less, more preferably 0.3% by mass or less.

[0032] The carbon nanotube dispersion preferably contains a surfactant in addition to the carbon nanotubes. When depositing carbon nanotubes near the edge of a dispersion coating using the manufacturing method according to this embodiment, a carbon nanotube dispersion containing a surfactant is more likely to align the carbon nanotubes. The concentration of the surfactant in the dispersion is not particularly limited, but is preferably, for example, above the critical micelle concentration to approximately 5% by mass, more preferably 0.001% to 3% by mass, and particularly preferably 0.01% to 1% by mass. Furthermore, the surfactant contained in the carbon nanotube dispersion is preferably a nonionic surfactant. Unlike ionic surfactants, nonionic surfactants have a weak interaction with carbon nanotubes and can be easily removed after the dispersion is applied to the substrate. This allows for the formation of stable carbon nanotube conductive paths and an excellent TCR value. By aligning the carbon nanotubes, the contact area between the carbon nanotubes increases, increasing the number of conductive paths and lowering resistance. This allows for a large change in resistance with temperature. On the other hand, even when the carbon nanotubes are in a network state or have a low degree of orientation, the density and film thickness of the carbon nanotubes can be increased. Furthermore, using a nonionic surfactant with a long molecular length is preferable because it can suppress re-aggregation of the carbon nanotubes and maintain the network state. When the carbon nanotubes form a dense network, the number of contact points between the carbon nanotubes increases, increasing the number of conductive paths and reducing resistance. Furthermore, since the metallic carbon nanotubes contained in the network state are unlikely to connect to each other and connect between electrodes, the semiconducting properties are significant, allowing for a large change in resistance with temperature.

[0033] The nonionic surfactant can be appropriately selected, but it is preferable to use one or a combination of multiple nonionic surfactants having a polyethylene glycol structure, such as polyoxyethylene alkyl ethers.

[0034] The solvent for the carbon nanotube dispersion is not particularly limited as long as it can disperse and suspend carbon nanotubes. Examples include water, heavy water, organic solvents, and mixtures thereof, with water being preferred.

[0035] The method for separating and preparing a carbon nanotube dispersion liquid having a high ratio of semiconducting carbon nanotubes, and the nonionic surfactant used in the method, can be, for example, that described in WO2020 / 158455, which is incorporated herein by reference.

[0036] The bolometer of this embodiment can be manufactured, for example, as follows, after forming the above-mentioned linear thin wire of semiconducting carbon nanotubes on a substrate. Since the carbon nanotubes are deposited on both edges of the line, the carbon nanotube thin wire is formed into two approximately parallel lines. A first electrode and a second electrode are fabricated on top of this carbon nanotube thin wire by gold vapor deposition or the like. It is also preferable that the carbon nanotubes in the carbon nanotube thin wire are oriented approximately parallel to the edges of the line shape. In this case, the electrodes are installed so that the orientation direction of the carbon nanotubes and the direction of the current flowing between the first electrode and the second electrode are approximately parallel.

[0037] In the bolometer of this embodiment, the distance between the first electrode and the second electrode is preferably 1 μm to 500 μm, and more preferably 10 μm to 300 μm. Furthermore, for miniaturization, 1 μm to 200 μm is more preferable. When the distance between the electrodes is 1 μm or more, degradation of the TCR characteristics can be suppressed even when a small amount of metallic carbon nanotubes is contained. Furthermore, when the distance between the electrodes is 50 μm or less, it is advantageous for application to an image sensor in a two-dimensional array. The lengths of electrodes 4 and 5 are preferably short as long as the carbon nanotubes can be connected to both electrodes and conduct electricity, and when the connection portion with the carbon nanotubes is, for example, 50 μm or less, it is advantageous for application to an image sensor in a two-dimensional array.

[0038] The electrodes are installed so that both of the two carbon nanotube thin wires formed on both edges of the line shape are connected, or so that only one of the thin wires is connected. When two thin wires are connected, the resistance is approximately halved, which is advantageous for reducing resistance, but the length of the electrode must be made longer than the length of the two thin wires. On the other hand, when only one thin wire is connected on one edge, the connection width between the carbon nanotube and the electrode can be made small, for example, 50 μm or less, which is advantageous for miniaturizing elements such as two-dimensional arrays. Furthermore, by applying the dispersion liquid with a width that matches the spacing between the elements, as shown in Figure 4 (top), the thin wires on both edges can be used at once for two rows of electrode pairs (the first and second rows), making array formation easy.

[0039] As shown in Figure 5, when the carbon nanotube thin wires are linear (extending across multiple electrode pairs) and therefore connect to adjacent electrode pairs, it is necessary to remove unnecessary carbon nanotubes, for example, by the following method. An acrylic resin solution such as polymethyl methacrylate (PMMA) is applied to the region 6 between the electrodes on the formed carbon nanotube thin wires 3 to form a PMMA protective layer. After heating at 200°C in the atmosphere to remove excess solvent, impurities, etc., the entire substrate is subjected to oxygen plasma treatment to remove excess carbon nanotubes and other materials in the carbon nanotube layer 3 in regions other than the region 6 covered by the PMMA layer.

[0040] An example of an array of this embodiment is shown in Figure 4 (bottom). The electrodes are installed so that two lines of carbon nanotubes straddle the electrode pairs in the first and second electrode rows, respectively. Then, as shown in the top two rows of Figure 5, PMMA is applied to region 6 containing carbon nanotubes between the electrodes (electrodes 4 and 5), and after drying at 200°C, unnecessary carbon nanotubes are removed by oxygen plasma treatment, as shown in the bottom two rows of Figure 5.

[0041] If necessary, a protective layer may be provided on the surface of the carbon nanotube layer. When the bolometer is used as an infrared sensor, the protective layer is preferably made of a material that is highly transparent in the infrared wavelength range to be detected, such as an acrylic resin such as PMMA, an epoxy resin, or Teflon (registered trademark).

[0042] The above embodiment describes a method for fabricating a bolometer element in the order of forming an APTES film on a Si substrate, fabricating a carbon nanotube layer, and then fabricating electrodes. However, the following fabrication order may be reversed. First, a first electrode and a second electrode are fabricated on a cleaned Si substrate by gold vapor deposition or the like. The substrate is then immersed in an APTES aqueous solution or sprayed with the APTES aqueous solution, washed with water, and dried. The APTES film is an insulating film, but it does not adhere to the gold electrodes because it bonds with the silicon oxide film surface of the substrate and presents amino groups on the surface. A carbon nanotube dispersion is applied to the substrate in a line shape and gradually dried. Carbon nanotubes are deposited around the edge of the line in a network-like manner or at least partially oriented, forming a carbon nanotube thin wire. Both ends of the thin wire are directly connected to the electrodes. If carbon nanotubes are connected between adjacent electrode pairs, unnecessary carbon nanotubes between the electrode pairs can be removed by oxygen plasma treatment or the like using the same method as above.

[0043] <Second embodiment> In one embodiment, a semiconducting carbon nanotube dispersion is applied in the form of circular dots. The substrate is then placed under conditions that allow the dispersion solvent to evaporate. Because the evaporation rate near the outer edge of the droplet (the periphery of the dot) is faster than near the center, the water in the dispersion gradually dries from the circular edge. The circular edge pins the contact line of the droplet, generating a capillary flow toward the edge within the droplet. Carbon nanotubes migrate outward from the center of the droplet and accumulate at the edge, oriented approximately parallel to the edge, forming a circularly oriented film (circular thin wires). The degree of carbon nanotube orientation can be controlled by adjusting conditions such as the diameter and length of the carbon nanotubes, surfactant concentration, and drying rate. By adjusting these conditions, a circular (doughnut-shaped) accumulation of carbon nanotubes in a network state in which the carbon nanotubes are barely oriented can also be obtained.

[0044] The size of the circular shape is preferably 10 μm to 1 cm in diameter, more preferably 20 μm to 1 mm, and even more preferably 30 μm to 500 μm.

[0045] The carbon nanotubes, carbon nanotube dispersion liquid and its preparation method, the width and thickness of the carbon nanotube thin wires formed, and the APTES solution used to form the intermediate layer can be appropriately applied as described in the first embodiment.

[0046] The bolometer of this embodiment can be manufactured, for example, as follows, after forming the circular thin wire of semiconducting carbon nanotubes on a substrate. The carbon nanotubes are deposited in a network shape around the circle or with at least some of them oriented, resulting in a doughnut-shaped carbon nanotube thin wire. The first and second electrodes are fabricated by gold vapor deposition so that the arc of the carbon nanotube circle is approximately parallel to the direction of current flowing between the first and second electrodes.

[0047] In the bolometer of this embodiment, the distance between the first electrode and the second electrode is preferably 1 μm to 500 μm, and more preferably 10 μm to 300 μm. Furthermore, for miniaturization, 1 μm to 200 μm is more preferable. When the distance between the electrodes is 1 μm or more, degradation of the TCR characteristics can be suppressed even when a small amount of metallic carbon nanotubes is contained. Furthermore, when the distance between the electrodes is 50 μm or less, it is advantageous for application to an image sensor in a two-dimensional array. The lengths of electrodes 4 and 5 are preferably short as long as the carbon nanotubes can be connected to both electrodes and conduct electricity, and when the connection portion with the carbon nanotubes is 50 μm or less, it is advantageous for application to an image sensor in a two-dimensional array.

[0048] The electrodes are arranged so that both of the two opposing arc-shaped thin wires are connected, as shown in Figure 6, or so that one arc-shaped thin wire is connected, as shown in Figure 7. When two arc-shaped thin wires are connected, the resistance is approximately halved, which is advantageous for reducing resistance, but the electrode length must be longer than the length of the two thin wires. On the other hand, when only one arc-shaped thin wire is connected, the connection width between the carbon nanotube and the electrode can be reduced, for example, to 50 μm or less, which is advantageous for miniaturizing elements, such as two-dimensional arrays. Furthermore, by applying the dispersion liquid in a circular pattern with a diameter that matches the spacing between the elements, as shown in Figure 7, two arc-shaped thin wires facing each other on both ends of the circle diameter can be used as two electrode pairs, the first and second rows, allowing for easy arraying. Figure 8 shows an example of an array formed in this embodiment. As in the first embodiment, PMMA is applied to the carbon nanotube-containing region 6 between the electrodes, and unnecessary carbon nanotubes are removed by oxygen plasma treatment.

[0049] Furthermore, if the array is to be made finer, as shown in Figure 9, a third row of third and fourth electrode pairs (7 and 8) can also be fabricated in the arc portion 90° from the opposing diametric arcs, in a direction approximately perpendicular to the first and second electrode pairs (4 and 5) of the first and second rows. Specifically, in each circle of the carbon nanotube circular thin wires arranged in a row, two arc-shaped portions facing each other in the vertical diameter direction are used for the first and second electrode pair rows, and a horizontal arc-shaped portion positioned approximately 90° from the diameter direction is used for the third electrode pair row, as shown in Figure 9. In other words, the third electrode pair row is arranged so that the electrode pairs (7, 8) constituting the third electrode pair row are approximately perpendicular to the electrode pairs (4, 5) constituting the first and second electrode pair rows. Such a bolometer electrode can be manufactured by forming a circular thin wire of carbon nanotubes arranged in a row from a single row of circular droplets of carbon nanotube dispersion liquid, and then arranging three rows of electrode pairs around the formed circular thin wire so that the circular thin wire straddles each electrode pair constituting each electrode pair row approximately perpendicularly. By removing unnecessary carbon nanotubes between the electrode pairs using oxygen plasma or the like, a bolometer electrode is formed with three rows of electrode pairs, in which arc-shaped thin wires cut from the single row of arranged circular thin wire of carbon nanotubes are connected to straddle each electrode pair approximately perpendicularly. In this case, as shown in FIG. 9, four elements can be fabricated from one circular thin wire, which reduces costs and simplifies the process.

[0050] 10 and 11 show further examples of arraying in an embodiment for fabricating a third row of electrodes. As shown in these examples, the array may be further fined by arranging electrode pairs in areas where circular thin wires arranged in the horizontal direction and / or circular thin wires arranged in the vertical direction overlap each other. As in the first embodiment, unnecessary carbon nanotubes are removed.

[0051] Because the carbon nanotube thin wires are doughnut-shaped, if carbon nanotubes are also connected to adjacent electrode pairs, it is necessary to remove unnecessary carbon nanotubes, for example, using the following method. An acrylic resin solution such as polymethyl methacrylate (PMMA) is applied to the area between the electrodes on the formed carbon nanotube thin wires to form a PMMA protective layer. After heating at 200°C in air to remove excess solvent, impurities, etc., the entire substrate is subjected to oxygen plasma treatment to remove excess carbon nanotubes and other materials in areas other than the area 6 of the carbon nanotube layer 3 covered with the PMMA layer.

[0052] In this embodiment, too, a protective layer may be provided on the surface of the carbon nanotube layer, if necessary. When the bolometer is used as an infrared sensor, the protective layer is preferably made of a material that is highly transparent in the infrared wavelength range to be detected, such as an acrylic resin such as PMMA, an epoxy resin, or Teflon (registered trademark).

[0053] The above embodiment describes a method for fabricating a bolometer element in the order of forming an APTES film on a Si substrate, fabricating a carbon nanotube layer, and then fabricating electrodes. However, the following fabrication method may be used: First, a first electrode and a second electrode are fabricated on a cleaned Si substrate by gold vapor deposition or the like. The substrate is then immersed in an APTES aqueous solution or sprayed with the APTES aqueous solution, washed with water, and then dried. The APTES film is an insulating film, but it does not adhere to the gold electrode because it bonds with the silicon oxide film surface of the substrate and presents amino groups on the surface. A carbon nanotube dispersion is applied to the substrate in a circular shape and gradually dried. Carbon nanotubes are deposited around the edges of the circular droplet in a network-like manner or with at least some of them oriented, forming a circular (doughnut-shaped) thin wire. Both ends of the circular thin wire are directly connected to the electrodes. If carbon nanotubes are connected between adjacent electrode pairs, unnecessary carbon nanotubes can be removed using the same method as above.

[0054] <Third embodiment> The bolometer according to this embodiment has the same structure as that shown in FIG. 1, but uses a plastic substrate instead of the Si substrate 1. Also, polylysine is used instead of the APTES layer 2. Polylysine easily bonds to the surface of the plastic substrate and, like APTES, presents amino groups on its surface. Therefore, the polylysine film does not repel the carbon nanotube dispersion liquid and easily pins the dispersion droplets. The method for applying the polylysine film and the method for manufacturing the bolometer can use the same processes as those described in the first and second embodiments. In this embodiment, the substrate can be made flexible, so it can be used in flexible image sensors, etc.

[0055] In the above embodiment, APTES or polylysine was used as the material for the intermediate layer to enhance the bond between the substrate and the carbon nanotubes, but the material for the intermediate layer is not limited to these. The material for the intermediate layer is preferably a compound having both a partial structure that bonds or adheres to the substrate surface and a partial structure that bonds or adheres to the carbon nanotubes. This allows the intermediate layer to function as a mediator between the substrate and the carbon nanotubes. The bond between the substrate and the intermediate layer and the bond between the intermediate layer and the carbon nanotubes can utilize not only chemical bonds but also various intermolecular interactions such as electrostatic interactions, surface adsorption, and hydrophobic interactions.

[0056] Examples of the partial structure that bonds to or adheres to the substrate surface include hydrophobic moieties or hydrophobic groups such as alkoxysilyl groups (SiOR) and SiOH. Examples of the hydrophobic moieties or hydrophobic groups include methylene groups (methylene chains) and alkyl groups each having preferably 1 or more, more preferably 2 or more, and preferably 20 or less, more preferably 10 or less carbon atoms. Examples of the partial structure that bonds to or adheres to the carbon nanotube include amino groups such as a primary amino group (-NH2), a secondary amino group (-NHR1), and a tertiary amino group (-NR1R2), an ammonium group (-NH4), an imino group (=NH), an imide group (-C(=O)-NH-C(=O)-), an amide group (-C(=O)NH-), an epoxy group, an isocyanurate group, an isocyanate group, a ureido group, a sulfide group, and a mercapto group.

[0057] The material for such an intermediate layer is not particularly limited, and examples thereof include silane coupling agents. Silane coupling agents have both a reactive group that bonds to or interacts with inorganic materials and a reactive group that bonds to or interacts with organic materials in their molecules, and function to bond organic materials and inorganic materials. In this embodiment, for example, a silane coupling agent having both a reactive group that bonds to a substrate such as a Si substrate and a reactive group that bonds to carbon nanotubes is used to form a monolayer polymolecular film on the substrate that presents reactive groups that bond to carbon nanotubes, thereby fixing carbon nanotubes to the substrate.

[0058] Examples of silane coupling agents include: Silane coupling agents having an amino group and an alkoxysilyl group (aminosilane compounds), such as 3-aminopropyltrimethoxysilane, 3-aminopropylmethyltriethoxysilane, 3-aminopropylmethyltrimethoxysilane, 3-aminopropyltriethoxysilane (APTES), 3-(2-aminoethyl)aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyltrimethoxysilane, and N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane; silane coupling agents having an epoxy group and an alkoxysilyl group, such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyldiethoxysilane, and triethoxy(3-glycidyloxypropyl)silane; Isocyanurate-based silane coupling agents such as tris-(trimethoxysilylpropyl) isocyanurate; ureido-based silane coupling agents such as 3-ureidopropyltrialkoxysilane; mercapto-based silane coupling agents such as 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-mercaptopropyltriethoxysilane; Sulfide-based silane coupling agents such as bis(triethoxysilylpropyl)tetrasulfide; and Isocyanate-based silane coupling agents such as 3-isocyanatepropyltriethoxysilane; Examples include:

[0059] In particular, a silane coupling agent having an amino group (aminosilane compound) is preferred because of its good bonding property with carbon nanotubes.

[0060] Other examples of materials for the intermediate layer include polymers, such as cationic polymers, that have moieties that can bond or attach to a substrate, such as a plastic substrate, and reactive groups that bond to carbon nanotubes.

[0061] Examples of such polymers include poly(N-methylvinylamine), polyvinylamine, polyallylamine, polyallyldimethylamine, polydiallylmethylamine, polydiallyldimethylammonium chloride, polydiallyldimethylammonium trifluoromethanesulfonate, polydiallyldimethylammonium nitrate, polydiallyldimethylammonium perchlorate, polyvinylpyridinium chloride, poly(2-vinylpyridine), poly(4-vinylpyridine), polyvinylimidazole, poly(4-aminomethylstyrene), poly(4-aminostyrene), polyvinyl(acrylamide-co-dimethylaminopropylacrylamide), polyvinyl(acrylamide-co-dimethylaminoethylmethyl)acrylate, polyvinyl(acrylamide-co-dimethylaminoethyl ... acrylate), polyethyleneimine (PEI), DAB-Am and polyamidoamine dendrimers, polyaminoamides, polyhexamethylene biguanide, polydimethylamine-epichlorohydrin, products of alkylation of polyethyleneimine with methyl chloride, products of alkylation of polyaminoamides with epichlorohydrin, cationic polyacrylamides with cationic monomers, formalin condensation products of dicyandiamide, dicyandiamide, polyalkylenepolyamine polycondensates, naturally-based cationic polymers (e.g., partially deacetylated chitin, chitosan, and chitosan salts), synthetic polypeptides (e.g., polyasparagine, polylysine, polyglutamine, and polyarginine).

[0062] Among these polymers, cationic polymers having an amino group and a hydrophobic group or a hydrophobic portion are preferred from the viewpoint of immobilizing carbon nanotubes on a substrate.

[0063] By using such a polymer, an intermediate layer presenting multiple reactive groups that bond or attach to carbon nanotubes can be formed on the substrate. Although not particularly limited, such an intermediate layer is preferably a monolayer from the viewpoint of uniform attachment, and can have a thickness of 1 nm to 1 μm, preferably 2 nm to 100 nm.

[0064] The material of the intermediate layer can be appropriately selected taking into consideration the material of the substrate to be used. Here, the material constituting the substrate may be inorganic or organic, and any material commonly used in the art can be used without particular limitation. Examples of inorganic materials include, but are not limited to, glass, Si, SiO2, SiN, etc., and examples of organic materials include, but are not limited to, plastics, rubber, etc., such as polyimide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyethylene terephthalate, acrylonitrile styrene resin, acrylonitrile butadiene styrene resin, fluororesin, methacrylic resin, polycarbonate, etc. In one embodiment, materials used for flexible substrates are preferred.

[0065] Some or all of the above embodiments can be described as, but are not limited to, the following supplementary notes. [Appendix 1] A step of applying a semiconducting carbon nanotube dispersion liquid in a line shape or a circle shape on a substrate and drying the dispersion liquid to produce a pair of substantially parallel carbon nanotube thin wires on the edge of the line shape or a circular carbon nanotube thin wire on the circumference of a circle shape, wherein the line width of the thin wires is 5 μm or more; A method for manufacturing a bolometer, comprising the step of connecting a portion of the thin wire to a first electrode and a second electrode. [Appendix 2] A bolometer manufacturing method according to Appendix 1, wherein the width of the line shape or the diameter of the circle shape is 20 μm or more and 1 cm or less. [Appendix 3] 3. The method for producing a bolometer according to claim 1, wherein the carbon nanotube thin wire has a thickness of 30 nm or more and 1 μm or less. [Appendix 4] 4. The method for producing a bolometer according to any one of claims 1 to 3, wherein the dispersion of semiconducting carbon nanotubes contains semiconducting carbon nanotubes in an amount of 90 mass % or more of the total amount of carbon nanotubes. [Appendix 5] 5. The method for producing a bolometer according to claim 1, wherein the dispersion of the semiconducting carbon nanotubes contains a nonionic surfactant in an amount of not less than a critical micelle concentration and not more than 5% by mass. [Appendix 6] A method for manufacturing a bolometer according to any one of appendixes 1 to 5, comprising a step of connecting a line-shaped thin wire made from a line of linear droplets of carbon nanotube dispersion liquid, or a line of circular thin wire made from a line of circular droplets of carbon nanotube dispersion liquid, to two or more electrode pair arrays so that the line-shaped thin wire spans each electrode pair constituting the electrode pair arrays approximately perpendicularly. [Appendix 7] A bolometer comprising at least three rows of electrode pairs, arc-shaped thin wires cut out from circular thin wires of semiconducting carbon nanotubes arranged in a row are connected to three electrode pair rows so as to straddle each electrode pair constituting each electrode pair row approximately perpendicularly; A bolometer electrode in which one of the three electrode pair columns is arranged such that the electrode pairs constituting that electrode pair column are oriented substantially perpendicular to the electrode pairs constituting the other two columns. [Appendix 8] A method for manufacturing a bolometer electrode having at least three rows of electrode pairs, comprising the steps of: forming a circular thin wire of semiconducting carbon nanotubes aligned in a single row; a step of arranging three electrode pair rows so that the circular thin wires of the semiconducting carbon nanotubes are approximately perpendicular to each electrode pair constituting the electrode pair rows; Including, A method for manufacturing a bolometer electrode, in which one of three electrode pair columns is arranged so that the electrode pairs constituting that electrode pair column are approximately perpendicular to the electrode pairs constituting the other two electrode pair columns. [Appendix 9] A method for manufacturing a bolometer according to any one of appendices 1 to 6 and 8, comprising the steps of covering the carbon nanotube wire between the first electrode and the second electrode, which is a part of the line shape or an arc of the circular shape, and the connection portion between the carbon nanotube wire and the first electrode and the second electrode, with a protective film, and removing the carbon nanotube in the portion not covered by the protective film. [Appendix 10] The method for producing a bolometer according to any one of appendices 1 to 6 and 8 to 9, wherein the carbon nanotube dispersion is applied in a line shape or a circle shape onto the substrate using a dispenser, an inkjet printer, or a printer. [Appendix 11] The method for manufacturing a bolometer according to any one of appendices 1 to 6 and 8 to 10, wherein the bolometer is a bolometer array. [Appendix 12] 12. The method for manufacturing a bolometer according to any one of appendices 1 to 6 and 8 to 11, wherein the bolometer is an infrared sensor. [Example]

[0066] The present invention will be illustrated in more detail below with reference to examples, but the present invention is not limited to these examples.

[0067] Example 1 100 mg of single-walled carbon nanotubes (Meijo Nanocarbon Co., Ltd., EC1.0 (diameter: approximately 1.1 to 1.5 nm, average diameter 1.2 nm) were placed in a quartz boat and heat-treated in an electric furnace under a vacuum atmosphere. The heat treatment was carried out at 900°C for 2 hours. After the heat treatment, the weight was reduced to 80 mg, indicating that surface functional groups and impurities had been removed. The obtained single-walled carbon nanotubes were crushed with tweezers, and 12 mg of them were immersed in 40 ml of a 1 wt% aqueous solution of surfactant (polyoxyethylene (100) stearyl ether) and thoroughly submerged. Then, ultrasonic dispersion treatment (BRANSON ADVANCED-DIGITAL The solution was then heated in a SONIFIER device (50 W output) for 3 hours. This removed any carbon nanotube aggregates. This procedure removed bundles and residual catalyst, yielding a carbon nanotube dispersion. To observe the length and diameter of the carbon nanotubes, this dispersion was applied to an SiO2 substrate, dried at 100°C, and observed with an atomic force microscope (AFM). The results showed that 70% of the single-walled carbon nanotubes had lengths in the range of 500 nm to 1.5 μm, with an average length of approximately 800 nm.

[0068] The carbon nanotube dispersion obtained as described above was introduced into a double-tube separation device. Approximately 15 mL of water, approximately 70 mL of carbon nanotube dispersion, and approximately 10 mL of a 2 wt% surfactant solution were placed in the outer tube of the double-tube separation device, and approximately 20 mL of a 2 wt% surfactant solution was placed in the inner tube. The bottom lid of the inner tube was then opened, creating a three-layer structure with different surfactant concentrations. A voltage of 120 V was applied, with the lower side of the inner tube acting as the anode and the upper side of the outer tube acting as the cathode. Semiconducting carbon nanotubes migrated to the anode side. Meanwhile, metallic carbon nanotubes migrated to the cathode side. Semiconducting and metallic carbon nanotubes were successfully separated approximately 80 hours after the start of separation. The separation process was carried out at room temperature (approximately 25°C). The semiconducting carbon nanotube dispersion that had migrated to the anode side was collected and analyzed by optical absorption spectroscopy, revealing that the metallic carbon nanotubes had been removed. Furthermore, Raman spectroscopy revealed that 99 wt% of the carbon nanotubes in the carbon nanotube dispersion that migrated to the anode side were semiconducting carbon nanotubes. The diameter of the single-walled carbon nanotubes was approximately 1.2 nm, accounting for the majority (70% or more), and the average diameter was 1.2 nm.

[0069] The surfactant was partially removed from the carbon nanotube dispersion liquid containing 99 wt% of the semiconducting carbon nanotubes (the carbon nanotube dispersion liquid moved to the anode side) to adjust the surfactant concentration to 0.05 wt%. Then, carbon nanotube dispersion liquid A (referred to as dispersion liquid A) was adjusted so that the concentration of carbon nanotubes in the dispersion liquid was 0.01 wt%. This dispersion liquid A was used to form the carbon nanotube layer.

[0070] The SiO2-coated Si substrate was washed with acetone, isopropyl alcohol, and water, and then treated with oxygen plasma to remove organic matter from the surface. The substrate was then immersed in a 0.1% APTES solution for 30 minutes, rinsed with water, and dried.

[0071] Dispersion A was applied in the form of dots using a dispenser onto the APTES-attached substrate. The dot diameter was 360 μm, the dot spacing was 1 mm, and the droplet volume per dot was approximately 1 μL. Dispersion A was gradually dried at room temperature (approximately 25°C), atmospheric pressure, and 50% RH. It was washed with water, ethanol, and isopropyl alcohol, and then dried at 110°C. It was then heated in air at 200°C to remove nonionic surfactants and other substances from Dispersion A. When the edges of the dots were observed with an SEM, it was observed that the carbon nanotubes were highly oriented and gathered in a doughnut-shaped circle with a width of 10 μm to 20 μm from the edge, as shown in Figure 2. In addition, the SEM image was subjected to two-dimensional Fourier transform processing, and a frequency of -1 μm was obtained from the center in one direction. -1 +1μm from -1 The integrated value f of the amplitude up to the edge was calculated, and when the integrated value in the direction x where the integrated value f was maximum was defined as fx and the integrated value in the direction y perpendicular to the direction x was defined as fy, fx / fy was calculated to be 2.0. The thickness of the carbon nanotube layer was measured using a laser microscope and was found to be approximately 100 nm on average (average value of 10 points) at 10 μm from the edge.

[0072] Gold was vapor-deposited onto the arcs of the circular carbon nanotube aligned film to form first and second electrodes with a thickness of 300 nm and a distance of 100 μm. The electrodes were positioned so that the arc line was approximately parallel to the direction of current flow between the electrodes. At the same time, as shown in Figure 7, a second row of first and second electrodes was placed at positions opposite the arcs. Next, the carbon nanotubes between the first and second electrodes and the regions including the connections between the first and second electrodes and the carbon nanotubes were protected by applying a PMMA-anisole solution. The film was then dried in air at 200°C for 1 hour, and unnecessary carbon nanotubes connected to adjacent electrode pairs were removed by oxygen plasma treatment.

[0073] (Comparative Example 1) Carbon nanotube dispersion A was prepared in the same manner as in Example 1. After cleaning a Si substrate in the same manner as in Example 1, APTES was adhered to the entire surface of the substrate. When approximately 200 μL of dispersion A was dropped onto the substrate, dispersion A spread over the entire surface of the substrate. After cleaning with water, ethanol, and isopropyl alcohol, the substrate was dried at 110°C and then heated in air at 200°C to remove nonionic surfactants and the like. When the substrate was observed using an SEM, carbon nanotubes were found to be adhered in a random network pattern. The thickness of the carbon nanotube layer was measured using a laser microscope and was found to be approximately 10 nm on average.

[0074] Next, gold was deposited on the carbon nanotube layer as a first electrode and a second electrode to a thickness of 300 nm with a distance of 100 μm between the electrodes. The carbon nanotubes and the first and second electrodes were protected with PMMA of the same area as in Example 1, dried in air at 200°C for 1 hour, and unnecessary carbon nanotubes were removed by oxygen plasma treatment.

[0075] (Comparison between Example 1 and Comparative Example 1) Table 1 shows the film resistance measurement results at 300 K and the TCR values ​​in the range of 20°C to 40°C for the bolometers fabricated from the carbon nanotube films obtained in Example 1 and Comparative Example 1. It was found that the oriented carbon nanotube film of Example 1 had a resistance that was at least one order of magnitude lower than that of Comparative Example 1. This is because the carbon nanotubes in Example 1 were oriented, increasing the contact area of ​​the conductive paths between the carbon nanotubes. As a result, noise was reduced during sensor fabrication, and sensitivity was improved. [Table 1] [Explanation of symbols]

[0076] 1. Si substrate 2 APTES layer 3 Carbon nanotube layers 4 1st electrode 5 Second electrode 6 PMMA layers 7. Third electrode 8 4th electrode

Claims

1. A step of applying a semiconducting carbon nanotube dispersion liquid in a line shape or a circle shape on a substrate and drying the dispersion liquid to produce a pair of substantially parallel carbon nanotube thin wires on the edge of the line shape or a circular carbon nanotube thin wire on the circumference of a circle, wherein the line width of the thin wires is 5 μm or more; A method for manufacturing a bolometer, comprising the step of connecting a portion of the thin wire to a first electrode and a second electrode.

2. 2. The method for manufacturing a bolometer according to claim 1, wherein the width of the line shape or the diameter of the circle is 20 μm or more and 1 cm or less.

3. 3. The method for manufacturing a bolometer according to claim 1, wherein the carbon nanotube thin wire has a thickness of 30 nm or more and 1 μm or less.

4. 4. The method for producing a bolometer according to claim 1, wherein the semiconducting carbon nanotube dispersion liquid contains semiconducting carbon nanotubes in an amount of 90 mass % or more of the total amount of carbon nanotubes.

5. 5. The method for producing a bolometer according to claim 1, wherein the semiconducting carbon nanotube dispersion liquid contains a nonionic surfactant in an amount of not less than a critical micelle concentration and not more than 5% by mass.

6. A method for manufacturing a bolometer according to any one of claims 1 to 5, comprising a step of connecting a line-shaped thin wire manufactured from a line of linear droplets of carbon nanotube dispersion liquid, or a line of circular thin wire manufactured from a line of circular droplets of carbon nanotube dispersion liquid, to two or more electrode pair arrays so that the line-shaped thin wire straddles each electrode pair constituting the electrode pair arrays approximately perpendicularly.

7. A bolometer comprising at least three rows of electrode pairs, arc-shaped thin wires cut out from circular thin wires of semiconducting carbon nanotubes arranged in a row are connected to three electrode pair rows so as to straddle each electrode pair constituting each electrode pair row approximately perpendicularly; A bolometer in which one of the three electrode pair columns is arranged so that the electrode pairs constituting the electrode pair column are oriented substantially perpendicular to the electrode pairs constituting the other two columns.

8. 1. A method for manufacturing a bolometer having at least three rows of electrode pairs, comprising the steps of: forming a circular thin wire of semiconducting carbon nanotubes aligned in a single row; a step of arranging three electrode pair rows so that the circular thin wires of the semiconducting carbon nanotubes are approximately perpendicular to each electrode pair constituting the electrode pair rows; Including, A method for manufacturing a bolometer, in which one of three electrode pair columns is arranged so that the electrode pairs constituting that electrode pair column are oriented substantially perpendicular to the electrode pairs constituting the other two electrode pair columns.

9. A method for manufacturing a bolometer described in any one of claims 1 to 6 and 8, comprising a step of covering a carbon nanotube wire between a first electrode and a second electrode, which is a part of the line shape or an arc of the circular shape, and a connection portion between the carbon nanotube wire and the first electrode and the second electrode, with a protective film, and removing the carbon nanotube in a portion not covered by the protective film.

10. 10. The method for manufacturing a bolometer according to claim 1, wherein the carbon nanotube dispersion is applied to the substrate in a line shape or a circle shape using a dispenser, an inkjet printer, or a printer.

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