JP2012247189A - Graphene sensor, substance species analyzer using sensor, and method for detecting substance species using sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a graphene sensor capable of selectively and highly sensitively detecting a predetermined substance species even from a specimen solution in which a plurality of substance species are mixed.SOLUTION: The graphene sensor according to the present invention is a sensor using a graphene film as a sensing portion. The sensor has a field-effect transistor structure including: a channel of the graphene film formed on a substrate; a source electrode joined to one end of the channel; and a drain electrode joined to the other end of the channel. The graphene film is formed of graphene crystals that are parallel to the surface of the substrate, and a functional group adsorbing substance species to be detected or connected to the substance species to be detected is modified on the edge of the graphene crystal.

Description

  The present invention relates to a sensor using a graphene film as a sensing site, and more particularly to a graphene sensor that selectively detects a predetermined substance type from a specimen solution. In addition, the present invention relates to a substance type analyzer using the sensor and a substance type detection method using the sensor.

  As a conventional method for analyzing biological species such as DNA, there is a method of optical detection using a DNA microarray (DNA chip). The detection method using a DNA chip has the advantage of being able to examine a large number of gene expressions at once, but the analysis method is a specialized method that has the disadvantage of requiring complicated procedures and advanced knowledge. On the other hand, as a simpler and more sensitive analysis technique, a method of electrically detecting chemical species and biological species using nanomaterials has been energetically studied in recent years. It has been reported that by forming a transistor with a graphene film as a channel, a sensor that electrically detects chemical species and biological species (for example, the concentration of hydrogen ions and proteins in a solution) can be obtained (for example, (See Patent Document 1 and Non-Patent Document 1).

Here, graphene refers to a six-membered ring sheet in which benzene rings are spread on a two-dimensional plane, and does not constitute a closed curved surface. A carbon nanotube is formed by rounding graphene into a cylindrical shape to form a closed curved surface, and graphite is formed by stacking a large number of graphenes. Each carbon atom of graphene forms sp ² hybrid orbitals, and delocalized electrons exist above and below the sheet. Graphene is a promising material as a new material for “Post-Si” due to its unique material properties.

US 2007/0284557 A1

Yasuhide Ohno, Kenzo Maehashi, Yusuke Yamashiro, and Kazuhiro Matsumoto: “Electrolyte-Gated Graphene Field-Effect Transistors for Detecting pH and Protein Adsorption”, Nano Lett. 9, 2009, pp3318-3322.

  The graphene field-effect transistor in Non-Patent Document 1 uses a monoatomic graphene crystal (size: about 10 μm) mechanically separated from natural graphite as a channel by transferring it onto a thermal oxide film on a silicon substrate. It has a structure in which a source electrode and a drain electrode (thickness: 5 nm / 30 nm) are formed. The graphene field-effect transistor utilizes a channel potential change caused by an electric double layer formed at the interface between a graphene film (channel) and a sample solution (a solution in which hydrogen ions or proteins are dissolved as a species to be detected). It is a sensor to detect.

  However, the sensor described in Non-Patent Document 1 only measures a potential change caused by the electric double layer, and for this detection principle, a predetermined substance type is selectively detected from a sample solution in which a plurality of substance types are mixed. Difficult to do. In other words, there has been a problem that a pretreatment for selecting in advance a substance type to be detected for the specimen solution is required.

  Therefore, an object of the present invention is to provide a graphene sensor capable of selectively detecting a predetermined substance type with high sensitivity even from a specimen solution in which a plurality of substance types are mixed. It is another object of the present invention to provide a material species analyzer and a material species detection method using such a graphene sensor.

  In order to achieve the above object, the present invention provides a sensor using a graphene film as a sensing site, the sensor including a channel of the graphene film formed on a substrate and a source bonded to one end of the channel A field effect transistor structure including an electrode and a drain electrode joined to the other end of the channel, the graphene film is made of graphene crystal parallel to the surface of the substrate, and the edge of the graphene crystal is Provided is a graphene sensor characterized in that a functional group that adsorbs or binds a detected substance species to the detected substance species is modified.

  In order to achieve the above object, the present invention is an analyzer for selectively detecting a predetermined substance type, comprising a sample sampling unit, a detection unit, a control measurement unit, and a display unit, and the detection unit Provides a graphene sensor according to the present invention, a mechanism for applying a voltage to the drain electrode, and a mechanism for applying a voltage to the substrate.

  In order to achieve the above object, the present invention is an analyzer for selectively detecting a predetermined substance type, comprising a sample sampling unit, a detection unit, a control measurement unit, and a display unit, and the detection unit Comprises a graphene sensor according to the present invention, a mechanism for applying a voltage to the drain electrode, and a mechanism for applying a voltage to an analyte solution in contact with the channel. An analytical device is provided.

  In order to achieve the above object, the present invention provides a method for detecting a species using a graphene sensor according to the present invention, the method comprising contacting a sample solution containing the species to be detected with the channel, And detecting a change in the potential of the channel caused by the detection substance species adsorbed or bonded to the functional group to detect the detection substance species.

  In order to achieve the above object, the present invention provides a method for detecting a species using a graphene sensor according to the present invention, the method comprising contacting a sample solution containing the species to be detected with the channel, Detecting a change in current of the channel caused by binding of a detection substance species to the functional group to impart electrons or holes to the channel, and detecting the detection substance species. Provided is a method for detecting the type of substance.

  Note that the “graphene film” in the present invention is defined as a graphene film having 10 atomic layers or less. This is because when the graphene film exceeds 10 atomic layers, it exhibits metallic properties and the semiconductor current amplification action becomes dilute. A graphene film having 5 atomic layers or less is more preferable. Further, the “edge” of the graphene crystal means a surface other than the c-plane (so-called a-plane or b-plane) of the graphene crystal.

  According to the present invention, it is possible to provide a graphene sensor that can selectively detect a predetermined substance type with high sensitivity even from a sample solution in which a plurality of substance types are mixed. In addition, a material species analyzer and a material species detection method using such a graphene sensor can be provided. For example, by using the graphene sensor according to the present invention as a biosensor for medical diagnosis, disease diagnosis with high speed and high sensitivity becomes possible.

It is a perspective schematic diagram which shows the process of forming an aluminum oxide film | membrane on a board | substrate. It is a perspective schematic diagram which shows the process of patterning an aluminum oxide film. It is a perspective schematic diagram which shows the process of forming a graphene film on an aluminum oxide film. It is a perspective schematic diagram which shows the process of forming an electrode in the both ends area | region of a graphene film. It is a perspective schematic diagram which shows the process of forming the bank which comprises the flow path or pool for making a sample solution contact a channel. It is a perspective schematic diagram which shows an example of the graphene sensor which concerns on the 2nd Embodiment of this invention. It is a plane schematic diagram which shows an example of the shape of a channel. It is a plane schematic diagram which shows another example of the shape of a channel. It is a plane schematic diagram which shows another example of the shape of a channel. It is an enlarged plane schematic diagram which shows an example of the channel which consists of many graphene crystal pieces. It is a perspective schematic diagram which shows an example of the material type | mold detection method which concerns on this invention. It is a perspective schematic diagram which shows another example of the material seed | species detection method which concerns on this invention. It is a schematic diagram which shows an example of the substance kind detection apparatus which concerns on this invention.

  As described above, the graphene sensor according to the present invention is a sensor using a graphene film as a sensing portion, and the sensor is bonded to a channel of the graphene film formed on a substrate and one end of the channel. A field effect transistor structure including a source electrode and a drain electrode joined to the other end of the channel, wherein the graphene film is made of a sheet of graphene crystal parallel to the surface of the substrate, The edge is characterized in that a functional group that adsorbs or binds to the detected substance species is modified.

Further, the present invention can add the following improvements and changes to the graphene sensor according to the above invention.
(1) When the distance between the source electrode and the drain electrode is L, the total extension of the edge of the graphene crystal in the channel is 20L or more.
(2) The graphene film is a polycrystalline body in which a large number of graphene crystal pieces overlap and are electrically joined.
(3) The average size of the graphene crystal pieces is 10 nm or more and 100 μm or less.
(4) The functional group is a probe DNA, and the probe DNA is a DNA fragment having a known base sequence that is a single strand that forms a DNA double helix structure.
(5) The functional group is an antigen that selectively binds to a predetermined antibody.
(6) The functional group is an enzyme that selectively decomposes a predetermined substance.
(7) The functional group is a functional group that selectively binds to a predetermined ion or a functional group that selectively binds to a mediator that selectively binds to a predetermined ion.
(8) An insulating layer of a patterned aluminum oxide film is formed between the substrate and the graphene film, and the graphene film is formed only on the surface of the aluminum oxide film.
(9) A bank constituting a flow path or a pool for bringing a sample solution containing the detected substance species into contact with the channel is further formed.

  Embodiments according to the present invention will be described below with reference to the drawings. However, the present invention is not limited to the embodiments taken up here, and may be improved or combined as appropriate without departing from the scope of the invention. In addition, the same code | symbol is attached | subjected to the part which is synonymous in drawing, and the overlapping description is abbreviate | omitted.

[Graphene sensor according to first embodiment]
An example of the graphene sensor according to the first embodiment of the present invention will be described along a manufacturing procedure. FIG. 1A to FIG. 1E are schematic perspective views each showing one step in the production of a graphene sensor. FIG. 1A is a schematic perspective view showing a step of forming an aluminum oxide film on a substrate. As shown in FIG. 1A, first, as a substrate 100, a silicon single crystal substrate 101 (for example, having a diameter of 2 inches, having a silicon oxide film 102 (for example, a thermal oxide film having a thickness of 20 to 300 nm) formed on the surface thereof is used. Prepare a thickness of 500 to 600 μm). Next, an aluminum oxide film 103 having a corundum structure is formed on the surface of the substrate 100 (the surface of the silicon oxide film 102) by a vapor phase growth method such as a sputtering method, an ion beam method, or a laser evaporation method.

Here, in forming the aluminum oxide film 103, it is desirable to control the composition thereof to be Al _2-x O _{3 + x} (x ≧ 0), and Al _2-x O _{3 + x} (x> 0). It is more desirable to control so that it becomes. The composition can be controlled, for example, by controlling the oxygen partial pressure during vapor phase growth. By forming the aluminum oxide film 103 having an oxygen-rich composition equal to or higher than the stoichiometric composition, graphene crystal grains having a large average size (for example, an average size of 30 nm or more) can be grown. The electrical resistance of the film can be reduced. In the graphene sensor according to the present invention, it is preferable that the aluminum oxide film 103 is formed as an underlayer that is in direct contact with the graphene film. However, even if the aluminum oxide film 103 is not formed, the effect of the present invention is exhibited. Is done.

  There is no particular limitation on the method for forming the aluminum oxide film 103. As a result, a method other than the vapor phase growth method may be used as long as the composition and the average film thickness can be controlled within desired ranges. Further, the substrate 100 on which the aluminum oxide film 103 is formed is not limited to the silicon single crystal substrate 101 on which the above-described silicon oxide film 102 is formed, and heat resistance against heat history in a later process and It can be appropriately selected in consideration of the application (for example, usage environment and usage method) as a graphene sensor. For example, various semiconductor substrates having various types of insulating films formed on the surface, various insulating substrates, and the like can be used.

  The arithmetic average surface roughness Ra of the aluminum oxide film 103 is desirably 1 nm or less. More desirably, it is 0.3 nm or less. When the arithmetic average surface roughness Ra is greater than 1 nm, the graphene film is difficult to grow parallel to the surface of the aluminum oxide film 103. This is probably because there is some correlation between the nucleation of graphene film growth and the arithmetic average surface roughness Ra. Furthermore, the maximum surface height Rz of the aluminum oxide film 103 is preferably 10 nm or less. More desirably, it is 3 nm or less.

  When the arithmetic average surface roughness Ra of the formed aluminum oxide film 103 is larger than 1 nm, it is processed to be 1 nm or less by polishing (for example, chemical mechanical polishing) or the like. Before the aluminum oxide film 103 is formed, the silicon single crystal substrate 101 or the silicon oxide film 102 may be processed in advance so that the arithmetic average surface roughness Ra is 1 nm or less. The arithmetic average surface roughness Ra and the maximum surface height Rz are based on JIS B 0601.

  The average thickness of the aluminum oxide film 103 to be formed is preferably 10 nm or more and 500 nm or less. When the average thickness of the polycrystalline aluminum oxide film 103 is less than 10 nm, the number of contact points between the crystal grains decreases and the coverage in the in-plane direction decreases (for example, the aluminum oxide film 103 has an island shape). Therefore, the surface flatness is deteriorated as a result. On the other hand, if it is thicker than 500 nm, cracks and the like due to thermal strain and the like in the subsequent process are likely to occur, and as a result, surface flatness (for example, arithmetic average surface roughness Ra) is deteriorated.

  FIG. 1B is a schematic perspective view showing a step of patterning the aluminum oxide film. As shown in FIG. 1B, the aluminum oxide film 103 formed on the substrate 100 is formed into a desired circuit in the same manner as in the conventional semiconductor process technology (for example, using photolithography, lift-off, reactive ion etching, etc.). Process to a pattern. At this time, the aluminum oxide film 103 is left in the portion 103 ′ that becomes a circuit, and the aluminum oxide film 103 in other portions is removed. The silicon oxide film 102 is preferably left as an insulating layer.

  FIG. 1C is a schematic perspective view illustrating a process of forming a graphene film on the aluminum oxide film. As shown in FIG. 1C, a graphene film 104 is formed on a portion 103 '(aluminum oxide film 103) serving as a circuit by chemical vapor deposition (CVD) using a carbon-containing compound as a raw material. As a result, the graphene film 104 grows with a uniform thickness along the surface of the portion 103 ′ (aluminum oxide film 103) to be a circuit in parallel with the surface.

  The film formation conditions of the graphene film 104 include, for example, propylene as a source gas and argon gas as a carrier gas, a mixed gas having an average source concentration of 0.15 to 3% by volume, an average flow rate of 15 to 50 cm / min (average on the substrate) The sample is supplied at a flow rate at a standard state and grown at a growth temperature of 450 to 1000 ° C. (preferably 750 to 1000 ° C.) for 0.1 to 60 minutes (preferably 0.1 to 10 minutes). In addition to propylene, other carbon-containing compounds such as acetylene, methane, propane, and ethylene can be used as the raw material.

As an example, a propylene / argon mixed gas having an average propylene concentration of 0.5% by volume was supplied at an average flow rate of 20.5 cm / min, and growth was performed at a growth temperature of 800 ° C. for 5 minutes. Observation of the formed graphene film with a scanning tunneling microscope and measurement of electric conductivity by a four-terminal method were performed. As a result, a graphene film (average number of atomic layers: 4 layers, electrical conductivity: 1 × 10 ⁴ S / cm or more) in which a large number of graphene crystal pieces (average size: about 50 nm) are overlapped and electrically joined is obtained. It was done. Moreover, the graphene film grew only on the aluminum oxide film, and the graphene film did not grow on the thermal oxide film from which the aluminum oxide film was removed. In other words, it was confirmed that the graphene film was selectively grown on the aluminum oxide film, which is a part to be a circuit. Note that it was separately confirmed that the average number of atomic layers in the formed graphene film is proportional to the growth time (that is, the average number of atomic layers can be controlled by the growth time).

  FIG. 1D is a schematic perspective view illustrating a process of forming electrodes in both end regions of the graphene film. As shown in FIG. 1D, a source electrode 105 is formed in one end region with a graphene film 104 region (channel, constricted region in the figure) serving as a sensing region in between, and a drain is formed in the other end region. An electrode 106 is formed. The width and length of the channel are preferably several μm to several hundred μm, respectively, as in the conventional biosensor.

  The basic structure of the field effect transistor is completed by the process shown in FIG. 1D (the gate electrode will be described later). There is no particular limitation on the method of forming the electrodes (the source electrode 105 and the drain electrode 106), and a conventional method (for example, a combination of photolithography and a sputtering method or various evaporation methods) can be used. Moreover, there is no special restriction | limiting also in the material of a metal electrode, The metal (for example, gold | metal | money, platinum, titanium etc.) normally used as an electrode can be used. An example is a laminated structure in which gold (100 nm thickness) is laminated on titanium (10 nm thickness).

  FIG. 1E is a schematic perspective view showing a step of forming a bank constituting a flow path or a pool for bringing a specimen solution into contact with a channel. As shown in FIG. 1E, a bank 107 is formed that constitutes a flow path or a pool for bringing a sample solution containing a substance to be detected into contact with a channel of the graphene film 104 serving as a sensing site. There is no particular limitation on the method for forming the bank 107, and for example, the bank 107 can be formed using a photoresist. As described above, the basic structure of the graphene sensor is completed. Note that the bank 107 is not necessary when the graphene sensor is immersed in the sample solution.

[Graphene Sensor According to Second Embodiment]
FIG. 2 is a schematic perspective view illustrating an example of a graphene sensor according to the second embodiment of the present invention. The graphene sensor according to the second embodiment uses a single-domain (single crystal) graphene crystal as the graphene film 104 ′ and does not use the aluminum oxide film 103 (part 103 ′ serving as a circuit). However, it differs from the graphene sensor according to the first embodiment described above.

  As a method for forming a graphene film made of single-domain graphene crystals, for example, a conventional method of transferring graphene crystals mechanically separated from graphite crystals onto the substrate 100 can be used. After the single-domain graphene crystal is transferred onto the substrate 100, the graphene film 104 'can be formed by processing it into a desired shape using an electron beam drawing apparatus or the like.

[Functional group modification to graphene film]
As described above, in the graphene sensor according to the present invention, a functional group containing a chemical substance that easily adsorbs or binds to a specific detected substance type on the edge of the graphene crystal is modified. . The functional group is chemically modified on the edge of the graphene crystal by a chemical reaction for forming a chemical bond. Examples of chemical bond formation by chemical reaction include formation of amide bond by dehydration condensation reaction of amine and carboxylic acid, formation of ester bond by condensation reaction of compound containing organic acid and hydroxyl group, various kinds using transition metals, etc. A technique such as formation of a carbon-carbon bond by a coupling reaction can be used. Further, when the distance between the source electrode 105 and the drain electrode 106 is L, the total extension of the edges of the graphene crystal in the channel is preferably 20 L or more. As a result, more functional groups can be modified, and the sensitivity of the sensor can be improved by an order of magnitude or more compared to conventional sensors.

  Here, when a single-domain graphene crystal is used as the graphene film as in the second embodiment, it is preferable to increase the total extension of the edges of the graphene crystal as follows. FIG. 3A is a schematic plan view showing an example of the shape of the channel. FIG. 3B is a schematic plan view illustrating another example of the shape of the channel. FIG. 3C is a schematic plan view showing still another example of the shape of the channel. The shape of the channel is not limited to these examples.

  When forming the graphene film 104 ′, as shown in FIG. 3A, the total extension of the edge 301 of the graphene crystal can be increased by making a hole in the channel of the graphene film 104 ′. Many functional groups 302 can be modified. In addition, as shown in FIG. 3B, slit processing is performed so that the channel of the graphene film 104 ′ has a meander shape, and the total extension of the edge 301 can be increased. can do. In addition, as shown in FIG. 3C, slit processing is performed so that the channel of the graphene film 104 ′ has a stripe shape, and the total extension of the edge 301 can be increased. can do.

On the other hand, when the graphene film is a polycrystal composed of a large number of graphene crystal pieces as in the first embodiment, there are the following advantages. FIG. 4 is an enlarged plan view schematically illustrating an example of a channel made up of a large number of graphene crystal pieces. As shown in FIG. 4, the channel of the graphene film 104 is a polycrystalline body in which a large number of graphene crystal pieces 104 ″ are overlapped, so that the total extension of the edge 301 of the graphene crystal becomes very long. A large number of functional groups 302 can be modified on the edge 301. In other words, since the density of the functional groups 301 can be very high, a highly sensitive graphene sensor can be realized. If the size of the crystal piece 104 ″ is a circle having a diameter of 50 nm, the functional group density is 105 / μm ² at the maximum, and it is considered possible to increase the sensitivity about 10,000 times that of the conventional sensor.

The average size of the graphene crystal pieces 104 ″ is preferably 10 nm to 100 μm, more preferably 30 nm to 5 μm, and further preferably 50 nm to 500 nm. The average size of the graphene crystal pieces 104 ″ is 10 nm. If it is less than the range, the electrical resistance of the graphene film 104 becomes too high, which makes it difficult to function as a sensor. Further, when the average size of the graphene crystal pieces 104 ″ exceeds 100 μm, the effect (high sensitivity) on the conventional sensor cannot be obtained so much.

[Functional group]
When the graphene sensor according to the present invention is used as a biosensor, examples of the functional group 302 include a DNA fragment having a known base sequence that forms a DNA double helix structure, and a predetermined antibody and a selective antibody. Preferably, an antigen that binds to an enzyme, an enzyme that selectively degrades a predetermined substance, and the like can be used. In addition, when the graphene sensor according to the present invention is used as an inorganic ion sensor, the functional group 302 is a functional group that selectively binds to a predetermined ion or a mediator that selectively binds to a predetermined ion. A functional group that selectively binds can be preferably used.

  More specifically, for example, one strand of a DNA fragment that is thought to increase the incidence of cancer is used as the functional group 302 of the probe DNA. On the other hand, a messenger RNA extracted from a patient's cell is prepared as a sample solution containing reverse transcriptase as a complementary DNA target DNA and brought into contact with the graphene sensor. If both base sequences are paired and hybridization occurs, it can be detected by the graphene sensor. In this way, genetic diagnosis can be performed.

  In addition, an antigen that specifically binds to lupus anticoagulant or antiphospholipid antibody that increases when myocardial infarction symptoms appear is used as the functional group 302. In contrast, the patient's blood is prepared as a sample solution and brought into contact with the graphene sensor. By detecting the antigen-antibody reaction, early and rapid diagnosis of myocardial infarction becomes possible.

  In addition, an enzyme that decomposes formaldehyde is used as the functional group 302, and the graphene sensor is left in a test atmosphere for a certain period of time. By detecting formaldehyde in the test atmosphere, it is possible to investigate the cause of sick house syndrome.

[Method of detecting species]
Next, a method for detecting a material type using the graphene sensor according to the present invention will be described. FIG. 5 is a schematic perspective view showing an example of the method for detecting a species type according to the present invention. As shown in FIG. 5, the sample solution flow path or the sample solution pool of the graphene sensor 500 of the present invention is filled with the sample solution 501, and brought into contact with the graphene film channel serving as a sensing site. Next, the current-voltage characteristic is measured by changing the drain voltage Vd under a constant gate voltage Vg. Here, the gate electrode is formed on the back surface side of the substrate 100 (the surface opposite to the surface on which the silicon oxide film 102 is formed), and the gate voltage Vg is applied to the graphene film from the back surface side of the substrate 100 through the silicon oxide film 102. Applied to the channel. By comparing this current-voltage characteristic with that of the reference solution measured in advance, it becomes possible to quantitatively measure the detected substance species.

  When the species to be detected is ionic, the potential of the channel changes due to adsorption to the graphene film channel, so that the voltage value at which the current value is the lowest in the current-voltage characteristics changes. From this voltage change amount, it is possible to quantify the type of substance to be detected. In addition, when the species to be detected is a species that imparts electrons or holes to the graphene film channel, the amount of current changes in the current-voltage characteristics. From this current change amount, it is possible to quantify the species of the substance to be detected.

  FIG. 6 is a schematic perspective view showing another example of the substance type detection method according to the present invention. 6, the gate electrode is formed so as to contact the sample solution 501 filled in the sample solution flow path or the sample solution pool of the graphene sensor 500 of the present invention, and the gate voltage Vg is set to the sample solution. Applied to the graphene film channel via 501. In this respect, it differs from the substance type detection method shown in FIG. In order to apply the gate voltage Vg via the sample solution 501, a method of directly immersing the microelectrode in the sample solution 501 or a method of integrating the microelectrode in advance in a portion in contact with the sample solution 501 (for example, the bank 107) Etc.

  Similarly to the substance species detection method shown in FIG. 5, when the substance species to be detected is ionic, the voltage value at which the current value is the lowest in the current-voltage characteristics of the graphene film channel changes. From this voltage change amount, it is possible to quantify the type of substance to be detected. Further, when the species of the substance to be detected is a substance that imparts electrons or holes to the graphene film channel, the amount of current changes in the current-voltage characteristics. From this current change amount, it is possible to quantify the species of the substance to be detected.

[Substance detection system]
FIG. 7 is a schematic diagram showing an example of a substance type detection device according to the present invention. As shown in FIG. 7, a substance type detection apparatus 700 according to the present invention includes a sampling unit 701, a measurement unit 702 incorporating the graphene sensor 500 (not shown) of the present invention, and a control / display unit 703. . The sampling unit 701 is a part for inserting a sample solution. The inserted specimen solution is sent to a measurement unit 702 having a built-in graphene sensor 500 to detect a target substance species to be detected. Electrical control of the graphene sensor 500 is performed by the control circuit of the control / display unit 703, and the measurement result is displayed on the monitor of the control / display unit 703. After one measurement, the graphene sensor 500 is automatically washed with pure water or the like to measure the next sample solution. In this way, it is possible to measure a plurality of specimen solutions in succession.

100 ... substrate, 101 ... silicon single crystal substrate, 102 ... silicon oxide film,
103 ... Aluminum oxide film, 103 '... Circuit part, 104,104' ... Graphene film,
104 "... graphene crystal piece, 105 ... source electrode, 106 ... drain electrode,
107 ... Bank, 301 ... Edge, 302 ... Functional group,
500 ... Graphene sensor, 501 ... Sample solution,
700 ... Substance type detection device, 701 ... Sampling unit, 702 ... Measuring unit, 703 ... Control / display unit.

Claims (14)

A sensor using a graphene film as a sensing site,
The sensor has a field effect transistor structure including a channel of the graphene film formed on a substrate, a source electrode joined to one end of the channel, and a drain electrode joined to the other end of the channel. ,
The graphene film is composed of a graphene crystal parallel to the surface of the substrate,
The graphene sensor is characterized in that a functional group that adsorbs or binds to a detected substance species is modified on an edge of the graphene crystal. The graphene sensor according to claim 1,
A graphene sensor, wherein a total extension of the edge of the graphene crystal in the channel is 20 L or more, where L is a distance between the source electrode and the drain electrode. The graphene sensor according to claim 1 or 2,
The graphene film is a polycrystal body in which a large number of graphene crystal pieces overlap and are electrically joined to each other. The graphene sensor according to claim 3,
A graphene sensor, wherein an average size of the graphene crystal pieces is 10 nm or more and 100 μm or less. The graphene sensor according to any one of claims 1 to 4,
The functional group is probe DNA;
The graphene sensor, wherein the probe DNA is a single-stranded DNA fragment having a known base sequence that forms a DNA double helix structure. The graphene sensor according to any one of claims 1 to 4,
The graphene sensor, wherein the functional group is an antigen that selectively binds to a predetermined antibody. The graphene sensor according to any one of claims 1 to 4,
The graphene sensor, wherein the functional group is an enzyme that selectively decomposes a predetermined substance. The graphene sensor according to any one of claims 1 to 4,
The graphene sensor, wherein the functional group is a functional group that selectively binds to a predetermined ion or a functional group that selectively binds to a mediator that selectively binds to a predetermined ion. The graphene sensor according to any one of claims 1 to 8,
Between the substrate and the graphene film, an insulating layer of a patterned aluminum oxide film is formed,
The graphene sensor, wherein the graphene film is formed only on a surface of the aluminum oxide film. The graphene sensor according to any one of claims 1 to 9,
A graphene sensor, further comprising a bank constituting a flow path or a pool for contacting a sample solution containing the species to be detected with the channel. An analyzer that selectively detects a predetermined substance type,
A sample sampling unit, a detection unit, a control measurement unit, and a display unit;
The detection unit includes the graphene sensor according to claim 1, a mechanism for applying a voltage to the drain electrode, and a mechanism for applying a voltage to the substrate. Characteristic material species analyzer. An analyzer that selectively detects a predetermined substance type,
A sample sampling unit, a detection unit, a control measurement unit, and a display unit;
The detection unit applies a voltage to the graphene sensor according to any one of claims 1 to 10, a mechanism for applying a voltage to the drain electrode, and a sample solution in contact with the channel. And a mechanism for analyzing the species. A substance type detection method using the graphene sensor according to any one of claims 1 to 10,
Contacting a sample solution containing the species to be detected with the channel;
Detecting the change in potential of the channel caused by the detection or detection of the detected substance species adsorbed to or bound to the functional group, thereby detecting the detected substance type. A substance type detection method using the graphene sensor according to any one of claims 1 to 10,
Contacting a sample solution containing the species to be detected with the channel;
Detecting the change in the current of the channel caused by binding of the substance species to the functional group and imparting electrons or holes to the channel to detect the substance species to be detected. Characteristic species detection method.

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