JP6614729B2 - Sample collection device, analyzer including sample collection device, and method for producing sample collection device - Google Patents

Description

  The present invention relates to a sample collection device, an analyzer including the sample collection device, and a method for manufacturing the sample collection device. In particular, the sample collection device becomes superhydrophilic by having nanowires with a titanium dioxide coating layer having an anatase crystal structure on the surface, and a water film is formed on the surface of the sample collection device. The present invention relates to a sample collection device capable of collecting a minute sample floating in the air, an analysis apparatus including the sample collection device, and a method for manufacturing the sample collection device.

  It has been pointed out that harmful and dangerous substances such as PM2.5, viruses, pollen, fungi, and toxins floating in the atmosphere may affect the health of living bodies such as humans. Therefore, it is necessary to accurately analyze these harmful and dangerous substances in the atmosphere so that humans can live a safe and comfortable life.

  For example, as an apparatus / method for analyzing PM2.5, a method of measuring PM2.5 collected on a filter by X-ray fluorescence analysis is known (see Patent Document 1).

  As another method for measuring particles contained in the atmosphere, the atmosphere is sucked through a filter impregnated or coated with a drug that reacts with the measured particles, and the air is sucked even after the filter collects the measured particles. Subsequently, there is known a particle collection method in which a measurement particle is moistened with moisture in the atmosphere to be reacted with a drug and fixed (see Patent Document 2).

JP 2008-261712 A JP 2007-71653 A

  In order for anyone to easily measure harmful and dangerous substances (samples) around us, the entire device needs to be downsized and simplified. However, in each of the inventions described in Patent Documents 1 and 2, a sample in the atmosphere is sucked by a suction means and collected in a filter. For this reason, there is a problem that the suction device and the power source for driving the suction device are required, and the apparatus becomes large.

  In recent years, analysis methods for detecting the size of fine particles by measuring changes in ion current when the fine particles pass through fine holes or channels formed on a substrate have been developed. This analysis method can reduce the size of the apparatus because the fine particles contained in the solution only need to pass through fine holes or channels by electrophoresis or the like. Therefore, application to a sample analyzer in the atmosphere is expected.

  By the way, when measuring the sample in air | atmosphere by the said analysis method, it is necessary to collect the sample in air | atmosphere to a solution. In order to collect the sample in the atmosphere in the solution, for example, a method of bubbling the atmosphere in the solution using a compressor or the like can be considered. However, in order to bubble the atmosphere in the solution, there is a problem that the apparatus becomes large. In order to reduce the size of the analyzer, it is also necessary to reduce the size of a device for collecting samples in the atmosphere. However, at present, a small device that can collect a sample in the atmosphere in a solution is not known.

  The present invention has been made in order to solve the above-mentioned conventional problems, and as a result of extensive research, (1) when a nanowire having a coat layer formed of titanium dioxide having an anatase crystal structure is formed on the surface of the substrate, Because the surface becomes superhydrophilic, (2) the substrate surface becomes superhydrophilic, the contact angle of the solution dropped on the substrate becomes almost zero, and (3) the contact angle becomes almost zero. Since the solution dropped on the substrate spreads in a thin film (water film) without forming water droplets, the entire surface of the substrate can be in contact with a sample in the atmosphere. (4) The coat layer is made of titanium dioxide having an anatase crystal structure. It was newly found that when the formed nanowire is formed on the substrate surface, the superhydrophilic performance can be maintained over a long period of time.

  The present invention relates to a sample collection device, an analysis apparatus including the sample collection device, and a method for manufacturing the sample collection device shown below.

(1) including a substrate, nanowires formed on the substrate,
The nanowire includes a core nanowire and a coat layer formed on the outer periphery of the core nanowire,
The coat layer is titanium dioxide having an anatase crystal structure.
Sample collection device.
(2) a liquid supply mechanism for supplying a liquid to the substrate;
The sample collection device according to (1), comprising at least
(3) an air supply mechanism for supplying air to the substrate;
The sample collection device according to (1) or (2), comprising:
(4) The sample collection device according to any one of (1) to (3) above,
Analysis department,
Analytical device including.
(5) forming a core nanowire on the substrate;
Forming a titanium dioxide coating layer on the outer periphery of the formed nanowire;
A heating step for converting amorphous titanium dioxide into anatase crystal structure by heating,
A method for manufacturing a sample collection device, comprising:

  The solution dropped on the sample collection device of the present invention spreads in a thin film shape without becoming water droplets. Therefore, samples in the atmosphere can be collected on the entire surface of the sample collection device. Moreover, the sample collection device of the present invention can maintain superhydrophilic performance over a long period of time as compared with a substrate such as glass surface-treated with titanium dioxide. Therefore, the function as a sample collection device can be maintained over a long period of time.

FIG. 1A is a diagram for explaining the outline of the device 1 of the present invention. FIG. 1B is a cross-sectional view of the nanowire 3. FIG. 2 is a diagram showing an example of an embodiment of the device 1 of the present invention. FIG. 3 is a diagram showing an outline of the analyzer 1-1 of the present invention. 4A is a drawing-substituting photograph, which is a photograph of the device 1 produced in Example 1. FIG. FIG. 4B is a drawing-substituting photograph, which is an SEM image in which the surface of the device 1 is magnified 15,000 times. 5 (A) to 5 (D) are photographs substituted for drawings, a scanning transmission electron microscope of the nanowire of the device 1 manufactured in Example 1, and FIG. 5 (E) is the arrow direction of FIGS. 5 (C) and 5 (D). It is a graph showing the intensity | strength of the characteristic X-ray of Zn and Ti in the distance. FIG. 6 is a graph showing the X-ray diffraction measurement results of the glass substrate formed in Reference Example 1 on which the TiO ₂ layer is formed. FIG. 7 is a graph showing the measurement results of the contact angle of the device 1 of Example 1 and Comparative Example 1. FIG. 8 is a graph showing the measurement results of the contact angles of the glass substrates of Comparative Examples 2 and 3. FIG. 9A is a graph showing the change over time of the device produced in Example 1, and FIG. 9B is the graph showing the change over time of the glass substrate produced in Comparative Example 2. FIG. 10A is a diagram showing an outline of the experimental apparatus manufactured in Example 2. FIG. FIG. 10B is a drawing substitute photograph, which is a photograph of the device 1 portion. FIG. 11A is a drawing substitute photograph, which is an SEM photograph of the surface of the device 1 and an enlarged photograph of the sample portion. FIG. 11B is a drawing-substituting photograph, which is an SEM photograph of the waste liquid obtained by centrifuging the liquid discharged by the liquid discharge mechanism and an enlarged photograph of the sample portion. FIG. 12 shows the results of analyzing the nanowires of the devices fabricated in Comparative Examples 4 and 5 and Example 3. The upper (A) is a drawing substitute photo, a STEM image of nanowires, the middle (B) is a drawing substitute photo, an element mapping image by STEM-EDS, and the lower (C) is the characteristic X-ray intensity of Zn and Ti. It is a graph to represent. FIG. 13 shows the results of analyzing the nanowires of the devices fabricated in Comparative Examples 4 and 5 and Example 3. The upper (A) is a drawing-substituting photograph, a TEM image of the nanowire, and the lower (B) is a drawing-substituting photograph, which is a limited-field electron diffraction pattern. Moreover, (C) represents the surface interval measured from the diffraction pattern. FIG. 14 is a diagram showing the measurement results of the crystal structure of the nanowires of the devices fabricated in Comparative Examples 4 and 5 and Example 3. FIG. 15 is a graph showing changes over time of the device produced in Example 3 and the glass substrate produced in Comparative Example 2. FIG. 16 is a photograph substituted for a drawing, FIG. 16A is a photograph of the device used in Example 4, and FIG. 16B is a photograph taken from the side of the device. FIG. 17B is a drawing-substituting photograph, and an SEM photograph of a sample directly collected by a filter. FIG. 17A is a graph showing a dust size distribution (N = 474) analyzed from the SEM photograph of FIG. is there. FIG. 17D is a drawing-substituting photograph, and an SEM photograph of a sample contained in the liquid discharged by the liquid discharge mechanism, and FIG. 17C is a dust size distribution analyzed from the SEM photograph of (D) (N = 350). ).

  Hereinafter, a sample collection device (hereinafter sometimes simply referred to as “device”) of the present invention, an analysis apparatus including the device, and a device manufacturing method will be described in detail.

  FIG. 1A is a diagram for explaining the outline of the device 1 of the present invention. The device 1 of the present invention includes a substrate 2 and nanowires 3 formed on the substrate 2. FIG. 1B is a cross-sectional view of the nanowire 3, and the nanowire 3 includes a core nanowire 31 and a coat layer 32 formed on the outer periphery of the core nanowire 31. The coat layer 32 is formed of titanium dioxide having an anatase crystal structure. Therefore, since the surface of the nanowire 3 formed on the substrate 2 becomes superhydrophilic, the solution dropletized on the surface of the device 1 does not become a water droplet but forms a water film F spreading in a thin film shape.

  The substrate 2 is not particularly limited as long as it can form nanowires 3 and can withstand the temperature at the time of film formation using an atomic layer deposition apparatus described later, and examples thereof include glass and silicon.

The core nanowire 31 formed on the substrate 2 may be produced by a known method. For example, the core nanowire 31 may be grown by a known method by applying nanowire-forming particles or a catalyst. Examples of the nanowire-forming particles include ZnO. Nanowires using ZnO can be manufactured using a hydrothermal synthesis method. Specifically, first, ZnO is applied on the substrate 2. Next, the heated substrate 2 is immersed in a precursor solution in which zinc nitrate hexahydrate (Zn (NO ₃ ) ₂ .6H ₂ O) and hexamethylenetetramine (C ₆ H ₁₂ N ₄ ) are dissolved in deionized water. By doing so, ZnO nanowires can be grown. Note that the thickness of the core nanowire 31 can be changed by changing the concentration of the precursor solution.

Examples of the catalyst for producing the core nanowire 31 include gold, platinum, aluminum, copper, iron, cobalt, silver, tin, indium, zinc, gallium, chromium, and titanium. A nanowire using a catalyst can be produced by the following procedure.
(A) A catalyst is deposited on the substrate 2.
_{(B) SiO 2, Li 2} O, MgO, Al 2 O 3, CaO, TiO 2, Mn 2 O 3, Fe 2 O 3, CoO, NiO, CuO, ZnO, Ga 2 O 3, SrO, In 2 O ₃ , SnO ₂ , Sm ₂ O ₃ , EuO or the like, and the core nanowire 31 is formed by physical vapor deposition such as pulse laser deposition or VLS (Vapor-Liquid-Solid). In addition, the core nanowire 31 produced using a catalyst may be a nanowire having no branched chain or a nanowire having a branched chain.

The coat layer 32 is preferably formed by forming a TiO ₂ layer by vapor deposition using an atomic layer deposition apparatus (ALD apparatus) after forming the core nanowire 31. When the ALD apparatus is used, the thickness of the coat layer 32 can be adjusted at the atomic level. The TiO ₂ coat layer 32 may be made of a precursor that becomes TiO ₂ after lamination, and examples thereof include tetrakis (diethylamino) titanium (TDMAT: Tetrakis (diethylamido) titanium), TiCl _{4 and the} like.

The TiO ₂ layer formed using the ALD apparatus is amorphous. By heating at a predetermined temperature and time, TiO ₂ can be converted into an anatase crystal structure. The heating temperature and time are not particularly limited as long as it can be converted into an anatase crystal structure, and for example, it may be heated at 300 to 500 ° C. for about 3 hours. The “titanium dioxide having an anatase crystal structure” may contain part of other crystal structures such as an amorphous part and rutile as long as the effects of the present invention are not impaired.

  FIG. 2 is a diagram showing an example of an embodiment of the device 1 of the present invention. The device 1 of the present invention may be provided with a liquid supply mechanism 5 and / or an air supply mechanism 6 as necessary. The device 1 of the present invention can take the sample S in the atmosphere into the water film F by forming the water film F on the surface of the substrate 2. The analysis of the sample S taken into the water film F may be performed by putting the liquid on the device 1 into the analysis unit of the analyzer, but the analysis is preferably automated. Therefore, the device 1 may be provided with a liquid supply mechanism 5 that can supply a liquid at a predetermined supply amount to the surface of the device 1 where the nanowires 3 are formed. The liquid supply mechanism 5 is not particularly limited as long as the liquid can be supplied, and a known pump or the like may be used. The liquid is not particularly limited as long as it is an aqueous liquid, but as will be described later, a conductive liquid is preferable when the liquid in which the sample S is taken is electrically analyzed. Examples of the conductive liquid include water, TE buffer, PBS buffer, HEPES buffer, and KCl aqueous solution.

  Since the surface of the device 1 is superhydrophilic, by forming a discharge channel or hole on the substrate 2 or by inclining the substrate, the liquid that has taken in the sample S flows out of the device 1, and the analyzer 1 What is necessary is just to reach | attain an analysis part. Further, a liquid discharge mechanism 51 may be provided so that substantially the same amount of liquid as that supplied from the liquid supply mechanism 5 can be discharged. When the liquid discharge mechanism 51 is provided, the amount of liquid taken in the sample S to be sent to the analysis unit becomes constant, so that quantitative analysis can be performed. The liquid discharge mechanism 51 is not particularly limited as long as the liquid can be discharged, and a known pump or the like may be used.

  The air supply mechanism 6 is not essential. It may be provided when it is necessary to increase the contact between the surface of the device 1 and air. The air supply mechanism 6 is not particularly limited as long as it can send air. A small device such as a fan is desirable, but a known device such as a compressor may be used if necessary. In addition, when providing the air supply mechanism 6, you may provide the container 8 which can cover the part which forms the water film of the device 1 at least as needed. Further, the container 8 may be formed with a hole 81 for allowing the air supplied by the air supply mechanism 6 to escape to the outside. When the air discharged from the container 8 is reused, a tube or the like may be connected to the hole 81 to collect the discharged air. In the embodiment shown in FIG. 2, the surface 82 of the container 8 that opposes the water film F is a flat surface, but the sample S contained in the air introduced into the container 8 can easily contact the water film F. Alternatively, the surface 82 may have a shape other than a plane. For example, by making the shape of a substantially triangular shape having an inclined surface such that the center of the surface 82 is close to the water film F, the air that has flowed into the container 8 flows toward the water film F along the inclined surface. Also good.

  FIG. 3 is a diagram showing an outline of the analyzer 1-1 of the present invention. The analysis apparatus 1-1 of the present invention includes at least the device 1 and the analysis unit 9 of the present invention. The analysis unit 9 is not particularly limited as long as it can analyze fine particles. For example, an analysis device (Waseem A. et al.) That measures a change in steady-state current flowing inside a pore by a voltage applied to the pore through a sample (micropore) formed on a substrate such as silicon. , Lab on a Chip, Vol. 12, pp. 2345-2352, 2012.) and an analysis apparatus (Naoya. Y et al. , “Tracking single-particle dynamics via combined optical and electrical sensing”, SCIENTIFIC REPORTS, Vol. 3, pp. 1-7, 2013, etc.).

  As described above, the device 1 of the present invention can be used as a sample collection device that collects PM2.5 or the like in the atmosphere, but may be used for other purposes. For example, since a water film can be formed on the board | substrate 2, it can use for the filter etc. of an air cleaner, for example. In addition, the device of the present invention has very high durability (maintaining superhydrophilic performance), and titanium dioxide has a photocatalytic function. Therefore, application to purification of solutions containing outer walls and organic substances can be expected.

  The present invention will be described in detail with reference to the following examples, which are provided merely for the purpose of illustrating the present invention and for reference to specific embodiments thereof. These exemplifications are for explaining specific specific embodiments of the present invention, but are not intended to limit or limit the scope of the invention disclosed in the present application.

[Production of Device 1]
<Example 1>
Device 1 was produced by the following procedure.
(1) Zinc oxide (ZnO) was laminated on a glass substrate (Slide glass S1112 manufactured by Matsunami Glass Industrial Co., Ltd.). For the lamination, an ALD apparatus (Savannah G2, manufactured by Cambridge Nanotech, the same applies to the following), diethyl zinc (DEZ; dietylzinc) as a precursor, H ₂ O as a second precursor, 100 ° C., 15 cycles. It laminated | stacked on conditions.
(2) Into a 50 mL beaker, 0.225 g of hexamethylenetetramine and 0.476 g of zinc nitrate hexahydrate were added and stirred to prepare a nanowire growth solution.
(3) The glass substrate laminated with ZnO in (1) above was immersed in the nanowire growth liquid prepared in (2) above.
(4) A core nanowire made of ZnO was produced on a glass substrate by placing the top of the beaker of the nanowire growth solution in an oven with many wraps and heating at 95 ° C. for 3 hours.
(5) A coating layer of titanium dioxide (TiO ₂ ) was formed around the core nanowire produced in (4) above. The coating layer was formed under the conditions of 100 ° C. and 100 cycles using an ALD apparatus, tetrakis (diethylamino) titanium (TDMAT) as the precursor, and H ₂ O as the second precursor.
(6) Next, the device 1 of the present invention was manufactured by heating at 500 ° C. for 3 hours.

  4A is a photograph of the device 1 produced in Example 1, and FIG. 4B is an SEM image in which the surface of the device 1 is magnified 15,000 times. As shown in FIG. 4B, it was confirmed that a large number of nanowires were formed on the surface of the substrate.

  Next, the device 1 manufactured in Example 1 was irradiated with ultrasonic waves, one nanowire was peeled from the substrate, and the distribution of Zn and Ti atoms in the nanowire was examined using a scanning transmission electron microscope (STEM). It was. The STEM uses a JSMOL JSM-7610F (Schottky field emission scanning electron microscope; FESEM) with a STEM function and an energy dispersive X-ray analyzer (EDS), 30 kV EDS 100 cycles, STEM mode. Observed at. FIGS. 5A and 5B are photographs enlarged 30,000 times, and it was confirmed that Zn (Photo A) and Ti (Photo B) atoms were contained from the tip to the base of the nanowire. Next, the STEM is magnified 150,000 times, and the characteristic X-rays of Zn and Ti emitted when an electron beam is applied to the nanowire surrounded by the broken line shown in FIGS. 5 (C) and 5 (D) The intensity of was detected. FIG. 5E is a graph showing the intensity of the characteristic X-rays of Zn and Ti at the distances in the directions of the arrows in FIGS. As shown in FIG. 5E, the strength of Zn becomes stronger (the amount of atoms is larger) as it is closer to the center of the nanowire. On the other hand, although the amount of Ti was small at the end of the nanowire, no significant change was observed near the center. From the above results, it was confirmed that Ti was coated on the outer periphery of the nanowire.

[Confirmation of anatase crystal structure]
<Reference Example 1>
The crystal structure can be examined using an X-ray diffractometer. First, as a reference example, a TiO ₂ layer was formed on a glass substrate, and changes in the crystal structure with and without heating were observed.

Specifically, an ALD apparatus, tetrakis (diethylamino) titanium (TDMAT) is used as a precursor, H ₂ O is used as a second precursor, and a TiO ₂ layer is formed on a glass substrate under conditions of 100 ° C. and 600 cycles. did. Subsequently, it heated at 500 degreeC for 3 hours. For comparison, a glass substrate that was not heated after laminating TiO ₂ was also prepared. Next, the crystal structure of TiO ₂ on the glass substrate was measured using an X-ray diffractometer (ATX-G manufactured by Rigaku Corporation). FIG. 6 is a diagram showing the measurement results, where “after” represents the measurement result of the crystal structure of the TiO ₂ layer after heating, and “before” represents the measurement result of the crystal structure of the TiO ₂ layer before heating. Below the graph, the value of 2θ (Cu Kα) / degree of anatase (Anatase) which is a crystal structure of TiO ₂ (J. Am. Ceram. Soc., 1996, 79, 1095-1099). Etc.) are also shown. In “before” before heating, no peak was observed around 25.5 which is the value of 2θ (Cu Kα) / degree of anatase, but in “after” after heating, as shown by the arrow, the anatase crystal structure A peak was observed. These results, after laminating TiO _2, TiO ₂ layers of anatase crystal structure by the heat treatment was confirmed to be able to form.

[Confirmation of wettability of device 1]
Next, the contact angle of the device 1 produced in Example 1 was examined. For the contact angle, DM-501 manufactured by Kyowa Interface Science Co., Ltd. was used, and a 0.5 μL droplet was produced from the syringe and deposited on the substrate, and an image after 1 second was obtained. From the acquired image, the static contact angle value was measured by the θ / 2 method.

<Comparative Example 1>
In the production of the device 1 of Example 1, the device which was not heated in (6) was designated as the device 1 of Comparative Example 1, and the wettability was confirmed by the same procedure as described above.

FIG. 7 is a graph showing the measurement results of the contact angle of the device 1 of Example 1 and Comparative Example 1. The contact angle of the device 1 of Example 1 was 0 degree. On the other hand, after forming the TiO ₂ coat layer of Comparative Example 1, the contact angle of the device 1 that was not heated was about 15 degrees.

<Comparative Examples 2 and 3>
An ALD apparatus, tetrakis (diethylamino) titanium (TDMAT) was used as a precursor, H ₂ O was used as a second precursor, and TiO ₂ was laminated on a glass substrate at 100 ° C. and 200 cycles. Next, after laminating TiO ₂ , a glass substrate heated at 500 ° C. for 3 hours was set as Comparative Example 2, and a glass substrate not heated was set as Comparative Example 3. The wettability was measured in the same procedure as in Comparative Example 1.

FIG. 8 is a graph showing the measurement results of the contact angles of the glass substrates of Comparative Examples 2 and 3. Although the contact angle of the glass substrate laminated with TiO ₂ was reduced by the heat treatment, the contact angle did not reach 0 degrees.

[Measurement of change in contact angle over time]
Next, the change over time of the wettability of the glass substrate produced in the device 1 produced in Example 1 and the comparative example 2 was confirmed. FIG. 9A is a graph showing the change over time of the device 1 produced in Example 1, and FIG. 9B is the graph showing the change over time of the glass substrate produced in Comparative Example 2. The glass substrate heat-treated by laminating TiO _{2 of} Comparative Example 2 showed a relatively low contact angle until about 6 days after the heat treatment, but the contact angle suddenly increased after 6 days. On the other hand, the device 1 of Example 1 surprisingly had a contact angle of 0 even after 30 days, just after the heat treatment. Therefore, since the device 1 of the present invention can form a water film on the surface of the device 1 over a long period of time, it is useful as a sample collection device.

[Sample collection experiment]
<Example 2>
Next, a sample collection experiment in air was performed using the device 1 of Example 1. FIG. 10A is a diagram showing an outline of the experimental apparatus, and FIG. 10B is a photograph of the device 1 portion of the experimental apparatus. The experimental apparatus was produced by the following procedure.
(1) A container produced by PDMS was placed on the device 1 produced in Example 1.
(2) A tube (PEEK tube: diameter 0.5 mm, two thin tubes in FIG. 10B) connected to a syringe pump as a liquid supply mechanism and a liquid discharge mechanism is inserted into the hole formed on the upper surface of the container Connected.
(3) A tube (PTFE tube: diameter 1.53 mm, thick tube in FIG. 10B) connected to a compressor as an air supply mechanism was connected to the hole formed on the upper surface of the container. An aerosol generator was provided between the device 1 and the compressor.
(4) A tube (PTFE tube: diameter 1.53 mm, thick tube in FIG. 10B) that discharges air sent from the compressor was connected to the hole formed on the upper surface of the container. The other end of the tube was positioned in the water bath.

  Next, a sample collection experiment was performed according to the following procedure. A water film was formed on the surface of the device 1 by sending water from the syringe pump (liquid supply mechanism) of the fabricated experimental apparatus to the surface of the device 1. Moreover, the same amount of water as the supply amount was discharged from the device 1 using a syringe pump (liquid discharge mechanism). Use urban atmospheric dust (No. 28) obtained from the National Institute for Environmental Studies as a sample, adjust the air containing dust with an aerosol generator, then send the adjusted air to the container, and remove the water film and dust from the device 1 The contained air was in contact. After a predetermined time, the device 1 was taken out and dried, and the substrate surface was observed with an SEM. FIG. 11A is an SEM photograph of the surface of the device 1 and an enlarged photograph of the sample portion. FIG. 11B is an SEM photograph of the waste liquid obtained by centrifuging the liquid discharged by the liquid discharge mechanism for 5,000 rcf for 10 minutes, and an enlarged photograph of the sample portion.

  As is clear from the photograph of FIG. 11A, by using the device 1 of the present invention, particulates such as PM2.5 in the atmosphere could be collected. In addition, since the liquid containing the fine particles collected from the device 1 can be collected, the sample can be continuously analyzed.

[Production of Device 1]
<Example 3>
(5) in Example 1 (5) 100 ° C., 100 cycles, (6) 500 ° C. for 3 hours, (5) 100 ° C., 200 cycles, (6) 350 ° C., 3 hours, A device 1 was produced in the same procedure as in Example 1 except that. Further, in the same procedure as in Example 1, one nanowire was peeled from the manufactured device 1 and a STEM image was taken, and the distribution of Zn and Ti atoms in the nanowire was examined.

<Comparative Examples 4 and 5>
Prepared in Example 3, Comparative Example a device which did not form a coating layer of titanium dioxide (TiO ₂₎ 4, as coating layer in Comparative Example 5 The device was but was not heat-treated to form the titanium dioxide (TiO ₂₎ did. Next, as in Example 3, a STEM image was taken and the distribution of Zn and Ti atoms in the nanowire was examined.

FIG. 12 shows nanowires of the devices manufactured in Comparative Examples 4 and 5 and Example 3. The upper (A) is a STEM image of the nanowire, the middle (B) is an element mapping image by STEM-EDS, and the lower (C). Is a graph showing the intensity of characteristic X-rays of Zn and Ti. As is clear from FIG. 12, it was confirmed that TiO ₂ was coated on the outer periphery of the nanowires of the devices fabricated in Example 3 and Comparative Example 5.

  Next, image observation and crystal structure analysis of the nanowires of the devices prepared in Comparative Examples 4 and 5 and Example 3 were performed. The procedure is to ultrasonically treat the nanowires from the substrate, drop the nanowire suspension onto the grid to prepare a sample, and a transmission electron microscope (TEM, manufactured by Hitachi High-Technologies Corporation, H-800) Observations were made. The upper part (A) of FIG. 13 is a TEM image of a nanowire, and the lower part (B) is a limited-field electron diffraction pattern. Table (C) shows the interplanar spacing (calculated by measuring the distance of the diffraction spot from the transmitted light of the electron beam) from the diffraction pattern. As is clear from FIG. 13A, it can be seen that Example 3 and Comparative Example 5 have a core-shell structure from the contrast. Moreover, as shown in FIGS. 13B and 13C, the spacing between the nanowires of Example 3 was changed by heating the nanowires of Comparative Example 5. And the value of the face spacing in Example 3 was the same as the face spacing exhibited by the anatase crystal structure. Note that the anatase crystal structure shows the spacing between the databases of the National Institute for Materials Science (MatNavi) (Zinc oxide_Wurtzite: http://crystdb.nims.go.jp/crystdb/search-details ? substance_id = 6694 & tabDetail = pageD & need_more_value = & pageD = 1 & reference_id = 4295075283 & pageA = 1 & pageSubP = 1 & errorCode = 0 & pageSubD = 1 & pageSubA = 1 & isVisiblePeriodicTable = false & tab = pageA & tabSub = pageA & isNeedMoreValueError = false & search-type = search-materials & condition_type = chemical_formula & pageS = 1 & pageP = 1 & pageSubS = 1 & condition_value = ZnO & need_more_type = prototype_number & material_id = 4296218650 & page = 1 & isConditionValueError = false, Titanium dioxide_anatase type: http://crystdb.nims.go.jp/crystdb/search-details?substance_id=11639&tabDetail=pageD&need_more_value=&pageD=1&reference_id=4294997799&pageA=1&pageSubP=1&errorCode=0&pageSubD=1&PageSubA&dic = false & tab = pageA & tabSub = pageA & isNeedMoreValueError = false & search-type = search-materials & condition _type = chemical_formula & pageS = 1 & pageP = 1 & pageSubS = 1 & condition_value = TiO2 & need_more_type = prototype_number & material_id = 4295281164 & page = 1 & isConditionValueError = false). From the above results, it was confirmed that the titanium dioxide film formed on the nanowire by ALD was amorphous and the crystal structure changed to anatase type by heating.

Next, the crystal structure of the nanowires of the devices prepared in Comparative Examples 4 and 5 and Example 3 was examined using an X-ray diffractometer (ATX-G manufactured by Rigaku Corporation). FIG. 14 shows the measurement results. Since only the nanowire of Example 3 had a peak around 25.5 which is the value of 2θ (Cu Kα) / degree of anatase, the titanium dioxide (TiO ₂ ) around the nanowire of the device of Example 3 It was confirmed that the coat layer had an anatase crystal structure.

  Next, using the devices of Example 3 and Comparative Example 2, the change with time was examined in the same procedure as [Measurement of change with time of contact angle] of Example 1. FIG. 15 shows the results of the measured change over time. In Example 1 [Measurement of change in contact angle with time], only 30 days were measured. Surprisingly, when about 2 months passed, the contact angle was 0 as in the case immediately after the heat treatment. From the above results, the device of the present invention can form a water film over a long period of time.

[Sample collection experiment]
<Example 4>
Next, in the sample collection experiment of Example 2, the device of Example 3 was used instead of the device of Example 1, and the container of Example 2 was replaced, and the center of the container surface facing the water film was the water film. An experimental apparatus was produced in the same procedure as in Example 2 except that a container having a shape having an inclined surface that was close to the surface was used. FIG. 16A is a photograph of the device used in Example 4, and FIG. 16B is a photograph from the side of the device. A portion surrounded by white in FIG. 16B is a space through which ventilation and water pass in the device. By forming a substantially triangular convex portion at the central portion of the container, the air flowing into the container from the air supply mechanism was formed to flow in the water film direction. Next, a collection experiment was performed by introducing an aerosol in which a dust sample similar to that in Example 2 was dispersed into a test apparatus from a tube. The liquid discharged by the liquid discharge mechanism was passed through a filter (pore diameter 0.1 μm: polycarbonate track-etched membrane filter manufactured by Merck), and dust in the discharged liquid was sampled on the filter. For comparison, dust was sampled on the filter by suspending the dust in pure water and passing the suspension through a similar filter.

  FIG. 17B is an SEM photograph of a sample directly collected by a filter, and FIG. 17A is a graph showing a dust size distribution (N = 474) analyzed from the SEM photograph. FIG. 17D is a SEM photograph of the sample contained in the liquid discharged by the liquid discharge mechanism, and FIG. 17C is a graph showing the dust size distribution (N = 350) analyzed from the SEM photograph. As is clear from FIGS. 17A and 17C, the size distributions of both were substantially the same. From the above results, it was revealed that the device produced in Example 3 can collect the sample regardless of the particle size of the sample contained in the air. Therefore, since the device produced in Example 3 can accurately measure the proportion of dust of various sizes contained in the atmosphere, it is useful for continuous monitoring of dust in the atmosphere.

  Since the sample collection device of the present invention can form a water film on the surface, it can collect a minute sample floating in the atmosphere on the entire surface of the device. Moreover, since a water film can be formed over a long period of time, the function as a sample collection device can be maintained over a long period of time. Therefore, it is useful for the analyzer industry.

Claims (6)

A substrate, comprising nanowires formed on the substrate;
The nanowire includes a core nanowire and a coat layer formed on the outer periphery of the core nanowire,
The coating layer is titanium dioxide having an anatase crystal structure,
A liquid supply mechanism for supplying a liquid for forming a liquid film on the surface of the substrate;
Sample collection device. An air supply mechanism for supplying air to the substrate;
The sample collection device according to claim 1, comprising: The substrate is substantially flat;
The sample collection device according to claim 1 or 2. The sample collection device according to any one of claims 1 to 3,
Analysis department,
Analytical device including. A sample collection method using a sample collection device,
The sample collection device is:
A substrate, comprising nanowires formed on the substrate;
The nanowire includes a core nanowire and a coat layer formed on the outer periphery of the core nanowire,
The coating layer is titanium dioxide having an anatase crystal structure,
The sample collection method is:
Forming a liquid film on the surface of the substrate;
Taking a sample in the atmosphere into the liquid film;
Sample collection method including The substrate is substantially flat;
The sample collection method according to claim 5.