DETECTION DEVICE, DETECTION METHOD, AND ELECTRODE WITH PROBE

According to one embodiment, a detection device is disclosed. The detection device includes a first region, a first electrode on the first region, a second region, a second electrode on the second region, a partition partitioning the first region and the second region and including a through hole, thereby communicating the first region with the second region. The device further includes a probe which binds specifically to the detection target, and is detachably connected to the first electrode, a detacher to detach the probe from the first electrode, a determination unit to determine whether the first liquid contains a detection target based on a change of electrical condition between the first electrode and the second electrode in a state where the first region and the second region are supplied with the first liquid and the second liquid, respectively.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2017-167604, filed Aug. 31, 2017, the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a detection device, a detection method for detecting, and an electrode with a probe, which are used to detect a detection target such as viruses and bacteria.

BACKGROUND

Pandemic of contagious diseases such as influenza is a great threat to the world of these days. Once a pandemic breaks out, there will be so many of patients and an impact to the world economic will be significant. A prevention plan of pandemic is thus a matter of great urgency.

To prevent pandemic, it is important that a patient with a certain disease is diagnosed in its early stage and that such a patient and their contact are isolated and restricted in order to delay the spread of disease. Furthermore, if a disease is correctly diagnosed in its early stage, the treatment of disease can be started before the condition becomes critical. Thus, deaths by the disease can be reduced. In consideration of the above points, performing correct diagnosis of a disease in its early stage is significantly important.

As a method of detecting a pathogen such as virus or bacterium, immunochromatography is used. In this detection method, diagnosis of a contagious disease can be performed simply and rapidly, and thus, it is widely used. However, the minimum detection sensitivity is low in this detection method, and thus, it is not for diagnosis of a disease in its early stage where viruses are not multiplied in a patient's body.

As another detection method, a method using nanopores is known. In this detection method, the minimum detection sensitivity is high. However, when the concentration of pathogen in a sample liquid is low, a time required to detect the pathogen becomes longer.

DETAILED DESCRIPTION

In general, according to one embodiment, a detection device is disclosed. The detection device includes a first region, a first electrode, a second region, a second electrode, a partition, a probe, a detacher, and a determination unit. The first region is to be supplied with a first liquid possibly containing a detection target. The first electrode is provided to the first region. The second region is to be supplied with a second liquid. The second electrode is provided to the second region. The partition partitions the first region and the second region each other, and includes a through hole to communicate the first region and the second region each other. The probe is detachably connected to the first electrode, and binds specifically to the detection target. The detacher detaches the probe from the first electrode. The determination unit determines whether the first liquid contains the detection target based on a change of electrical condition between the first electrode and the second electrode in a state where the first region and the second region are supplied with the first liquid and the second liquid, respectively.

According to another embodiment, a detection method using a detection device is disclosed. The detection device includes a first region, a first electrode provided to the first region, a second region, a second electrode provided to the second region, a partition partitions the first region and the second region each other, and provided with a through hole to communicate the first region and the second region each other, and a probe detachably connected to the first electrode and binds specifically to a detection target. The detection method includes supplying a first liquid and a second liquid to the first region and the second region, respectively, the first liquid possibly containing the detection target; separating the probe from the first electrode; determining whether the first liquid contains the detection target based on a change of electrical condition between the first electrode and the second electrode.

Embodiments will be described hereinafter with reference to the accompanying drawings. The drawings are schematic and conceptual, and the dimensions, the proportions, etc., of each of the drawings are not necessarily the same as those in reality. Further, in the drawings, the same reference symbols denote the same or corresponding portions, and overlapping explanations thereof will be made as necessary. In addition, as used in the description and the appended claims, what is expressed by a singular form shall include the meaning of “more than one.”

First Embodiment

FIG. 1is a view schematically depicting a detection device1according to the first embodiment.

The detection device1includes a vessel2, and a partition3provided therein. The partition partitions the vessel2into a first chamber (first region)11and a second chamber (second region)12.

A through hole4is provided to the partition3, which communicates the first chamber11and the second chamber12each other, and is a fine hole used as nanopore or micropore. The through hole4has a dimension such that a single detection target passes through the through hole4. Hereafter, the through hole4may be referred to as a fine hole4.

The detection target is, for example, a pathogen such as a virus or bacterium. In addition, the detection target maybe a component of pathogen, for example, a nucleic acid (DNA, RNA), protein, or cell. In the following description, the detection target is an influenza virus that is one of viruses.

A shape of the-through hole4is, for example, a circle as shown in a plan view ofFIG. 2. The partition3shown inFIG. 1corresponds to a cross-sectional view along line1-1ofFIG. 2. When the influenza virus having about 100 nm size is to be detected as the detection target, a diameter of the through hole4is, for example, 200-500 nm. The diameter of the influenza virus ranges between 80 and 120 nm in general, and thus, the diameter of the through hole4is, preferably, set to 200 to 300 nm in order to improve the detection sensitivity, for example.

The first chamber11is configured to be supplied with a sample liquid (first liquid) which is not shown, and the inside of the first chamber11can be filled with the sample liquid.

The sample liquid is an electrically conductive liquid containing a sample. The sample liquid is, for example, a liquid including the sample and a buffer solution, or a liquid including the sample and an electrolyte solution. The sample is collected from, for example, a biological body such as animal including human. The sample may possibly contain the detection target, and thus the sample liquid also may possibly contain the detection target.

The buffer solution includes, for example, phosphate buffered saline (PBS), tris-buffered saline (TBS), tris Ethylene diamine tetra acetic acid (TE), or 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES). The electrolyte solution is, for example, KCl aqueous solution. The buffer solution and the electrolyte solution have pH of approximately 7 to 8. When such a buffer solution is used, the influenza virus is negatively-charged in the sample liquid.

The second chamber12is configured to be supplied with non-sample liquid (second liquid) which is not shown, and the inside of the second chamber12can be filled with the non-sample liquid. The non-sample liquid is a conductive liquid which does not contain the sample, and is, for example, a buffer solution containing PBS or TE, or electrolyte solution such as a KCl aqueous solution.

A lower elected (first electrode)21is provided in the first chamber11. More specifically, the lower electrode21is provided on the lower surface in the first chamber11. The through hole4of the partition3is positioned above the lower electrode21.

A probe23is provided on an upper surface of the lower electrode21, and binds specifically to the detection target. The probe23is connected to (fixed on) the lower electrode21before using the detection device1(before executing the detection method), but the probe23is detached from the lower electrode23during use of the detection device1(during execution of the detection method).

FIG. 3is a view schematically depicting the probe23connected to the lower electrode21.

The probe23includes a first part23-1connected to the lower electrode21. InFIG. 3, the first part23-1is thiol (R—SH) having a functional group of —SH, where R, S, and H represent organic group, sulfur, and hydrogen, respectively. Hydrogen (not shown) of thiol is bound with the lower electrode21(covalent bound).

Instead of thiol, disulfide or thiocyanate may be used. In addition to an organic compound containing sulfur such as thiol or disulfide, a chemical compound containing organoselenium, organotellurium, isocyanide, isocyanate, or alkylsilane may be used.

As shown inFIG. 35, when an end10of the probe23is a functional group reactive to carbonic acid, amine, alcohol, or the like, one end20aof a different probe23′ can be bound to the end (functional group)10, and the other end20bof the probe23′ can be detachably connected to the lower electrode21.

When the probe23contains protein, the probe23can be detachably connected to a member containing, for example, mica, silica, or glass (a member different from the lower electrode21) by using imprinting technique. In that case, the probe23is not detachably connected to the lower electrode21, however the lower electrode21is required for the electrophoresis (electric field), as will be described later.

When the probe23contains DNA, the probe23can be detachably connected to, for example, a Si3N4substrate (substrate mainly containing silicon nitride).

When the probe23is connected to the lower electrode21, the material of the lower electrode21is selected such that the first part23-1can be detachably connected to the lower electrode21. In the present embodiment, the material of the lower electrode21contains gold (Au); one of the materials with which thiol can be combined. The surface of the lower electrode21contains gold; however, the entirety of the lower electrode21is not necessarily gold. Instead of gold, a material such as silver (Ag), copper (Cu), mercury (Hg), or platinum (Pt) can be used.

Note that the orientation of the lower electrode21may be set such that the first part23-1can be detachably connected to the lower electrode21.

As shown inFIG. 3, the probe23further includes a second part23-2which binds specifically to a detection target. The second part23-2is connected to the end of the first part23-1opposite to the lower electrode21side. The second part23-2contains, for example, antibody, nucleic acid, peptide, or chain of sugar.

Foreign substances in the sample liquid may be absorbed by the probe23in a non-specific manner. Thus, a material which can suppress non-specific absorption of foreign substances may be added to the probe23. The material may contain, for example, polyethylene glycol chain with molecular mass of 100 to 100000.

Referring back toFIG. 1, an upper electrode (second electrode)22is provided in the second chamber12. More specifically, the upper electrode22is provided on the upper surface in the second chamber12. The through hole4of the partition3is positioned below the upper electrode22. The upper electrode22is disposed to face the lower electrode21. The material of the upper electrode22is, for example, silver or silver chloride (AgCl). The material of the upper electrode22may be platinum or gold.

The detection device1further includes a direct current power supply31and a measurement circuit (measurement device)32which are connected in series with respect to the upper electrode22.

Now, a detection method using the detection device1will be explained.

Firstly, as shown inFIG. 4, the first chamber11is filled with a sample liquid41and the second chamber12is filled with a non-sample liquid42. The lower electrode21is immersed in the sample liquid41and the upper electrode22is immersed in the non-sample liquid42. The following description is given that the sample liquid41contains the detection target5.

The detection target5combines with the probe23. More specifically, as shown inFIG. 5, the detection target5binds specifically to an end of the second part23-2of the probe23.

Note that, inFIGS. 4 and 5, the detection target5is depicted as a particle; however, the detection target5may not be a particle when being depicted in a further enlarged manner.

Subsequently, a voltage is applied between the lower electrode21and the upper electrode22by the direct current power source31. In the present embodiment, a potential of the upper electrode (V2) is set greater than a potential of the lower electrode21(V1) (V1<V2). The sample liquid41and the non-sample liquid42are both conductive, and thus a current flows from the upper electrode22to the lower electrode21.

As a result, as shown inFIG. 6, the probe23is detached from the lower electrode21. Specifically, as shown inFIG. 7, the first part (thiol) of the probe23connected to the lower electrode21(gold) is reduced (gold-thiol reduction reaction), and the probe23is detached from the lower electrode21. As a result, the detection target5bound to the probe23is detached from the lower electrode21. In the following description, the detection target5bound to the probe23may simply be referred to as detection target5.

The detection target5in the sample liquid41in the first chamber11(that is, negatively charged influenza virus in this example) passes the fine hole4(liquid path) by electrophoresis (electric field), and moves to the non-sample liquid42in the second chamber12.

Note that, if the detection target5is positively charged, V1>V2 is set by the direct current power source31. As a result, the detection target5in the sample liquid41in the first chamber11passes the fine hole4(liquid path) by electrophoresis (electric field), and moves to the non-sample liquid42in the second chamber12. In this case, it is possible to use a probe23capable of being detached from the lower electrode21under the V1>V2 condition.

When the detection target5is positively charged, and the probe23configured to be detached from the lower electrode21under V1<V2 condition, is used, another power supply different from the direct current power supply31is used to set the condition V1<V2, for example. Thereafter, the V1>V2 condition is set by the direct current power supply31, and the detection target5in the sample liquid41in the first chamber11is moved to the second chamber12by electrophoresis (electric field).

When the direct current power source31is a variable power source, a condition of V1<V2 is set to detach the probe23from the lower electrode21, and then, a condition of V1>V2 is set to move the detection target5in the first chamber11into the second chamber12.

Referring back toFIG. 6, when the detection target5passes the fine hole4a current (current signals) measured by the measurement circuit32changes, for example, in a pulse shape as shown inFIG. 8, and a value of the current signal reduces. The reason is as follows.

When the detection target5is not passing through the fine hole4, the number of ions in the fine hole4, which is the current path between the lower electrode21and the upper electrode22is substantially constant, and thus, a substantially constant current signal (I2) flows between the lower electrode21and the upper electrode22. That is, when the detection target5is not passing through the fine hole4, a conductive state (electric state) between the lower electrode21and the upper electrode22is substantially constant.

On the other hand, when the detection target5passes the fine hole4, the number of ions in the fine hole4, which is current path between the lower electrode21and the upper electrode22is reduced by the detection target5. As a result, a current resistance in the fine hole4increases, and the current signal decreases. That is, when the detection target5passes the fine hole4, the conductive state between the lower electrode21and the upper electrode22changes. Then, after the detection target5passes the hole, the current signal returns to its original value12, and the conductive state between the lower electrode21and the upper electrode22becomes substantially constant.

Therefore, it is determined whether the sample liquid41contains the detection target5or not, based on a presence or absence of the change of conduction condition (change of the electric state) between the lower electrode21and the upper electrode22. The details will be explained below.

The value of current signal when the detection target5passes the fine hole4changes depending on the size, shape (steric structure), and surface state of detection target5. Therefore, it is determined whether the sample liquid41contains the detection target5or not by comparing the measured current value with a previously obtained reference which is reduction of a current signal corresponding to the detection target5.

For example, the size of an influenza virus which is the detection target5is basically well-known. Thus, only a reduction of current signal within a certain range can be regarded as a signal derived from the influenza virus, and others can be regarded as a signal derived from foreign substances.

The measurement circuit32has the above determination function, for example. That is, the measurement circuit32may be determination means. Alternately, a different device may have the above determination function instead of the measurement circuit32. In that case, the determination means includes both the measurement circuit32and the device.

Since only a single detection target5passing through the fine hole4can indicate a presence of the detection target5, the minimum detection sensitivity of the detection device1is high. Thus, in the present embodiment, the detection sensitivity can be improved.

Here, as shown inFIG. 9, with respect to a detection device without the probe on the lower electrode21(comparative detection device1′), the detection targets5diffuse in the sample liquid41. Thus, with the same concentration of detection targets5in the sample liquid41, the concentration of detection targets5in the vicinity of the fine hole4of the detection device1′ of comparative example is lower than that of the detection device1of the embodiment.

In general, the lower the concentration of the detection targets5in the vicinity of the fine hole4, the lower the possibility that the detection targets5pass through the fine hole4in a predetermined time, and the longer time requires to detect the detection target5.

In a detection method using the detection device1′ (detection method of comparative example), a long time is required to detect a detection target5unless the concentration of detection targets5in the first chamber11is 1×107/mL or more.

On the other hand, in the detection method using the detection device1(detection method of the present embodiment), even if the concentration of detection targets5in the first chamber is less than 1×107/mL, the concentration of detection targets5in the vicinity of the fine hole4becomes greater than 1×107/mL by virtue of the probe23. As a result, the detection method of the present embodiment can rapidly detect a detection target5even with the sample liquid41having such a low concentration of detection targets5that the detection has been difficult. As can be understood from the above, in the present embodiment, not only improvement of the detection sensitivity but also reduction of the detection time can be achieved.

In general, as the density of the probes23increases, the effect of the present embodiment (reduction of the detection time) increases. Furthermore, the density of probes23may not be uniform. For example, the density of probes23may be maximized right below the fine hole4and in the vicinity thereof.

Note that, when the detection target5does not exist in the sample liquid41, the current measured by the measurement circuit32does not change. Thus, when the change in the current signals (detection signal) is not detected in the measurement which is performed a predetermined period of time, it is determined that the sample liquid41does not contain the detection target5.

Furthermore, if a single detection target5passes the through hole4, a single pulse-like current signal reduction (detection signal) is generated. Thus, for example, on the basis of the number of detection signals in a certain period of time, the number of detection targets5in the sample liquid41can be estimated. From this estimated number, for example, whether or not the infection stage is early can be determined.

Note that, in the present embodiment, the configuration to measure the current value by the measurement circuit32is employed, however, a configuration to measure voltage by the measurement circuit32may be employed. In this case, the presence or absence of the detection target is determined on the basis of a change in voltage signals measured by the measurement circuit32(detection signal).

Now, an example of a manufacturing method of the detection device1of the present embodiment will be explained with reference toFIG. 10andFIGS. 11A to 11D.

FIG. 10illustrates an exploded perspective view of the detection device1of the present embodiment.FIGS. 11A to 11Dare cross-sectional views of a manufacturing method of the detection device1.FIGS. 11A to 11Dare cross-sectional views taken along a line with single-dots ofFIG. 10, as being viewed orthogonally to the arrow.

A groove51is formed on the surface of a first substrate50(FIGS. 10 and 11A). The surface of the first substrate50does not possess conductivity. The material of the first substrate50is an insulator which is, for example, glass, resin such as polydimethylsiloxane (PDMS), or silicon oxide (SiO2).

The groove51is used as a liquid path through which a liquid flows. The groove51includes, in a top view, two circular groove areas and a rectangular groove area connecting therewith (FIG. 10). The diameter of the circular groove areas is greater than a short side of the rectangular groove area. The groove51may be formed by using chemical treatment such as etching process or physical treatment such as curving.

Then, the lower electrode21is formed on the first substrate50(FIGS. 10 and 11A), and an extraction electrode21aof the lower electrode21is formed (FIG. 10). The lower electrode21is formed in the groove51. A process to form the lower electrode21and the extraction electrode21aincludes forming a conductive film using sputtering or evaporation, and etching the conductive film.

Then, the probe23shown inFIG. 1is formed on the lower electrode21.

Note that the probe23is omitted inFIGS. 10 and 11A to 11Ffor the simplification. The formation of probe23is performed by, for example, supplying a solution containing probes23to the lower electrode21while the extraction electrode21ais masked by a resist or the like. The functional group (—SH) of the probe23in the supplied solution is connected to the lower electrode21. Then, the mask is remove. As a result, the structure including the lower electrode21and the probe23connecting thereto is obtained. That is, the electrode with probe used in the detection device which, contributes to the improvement of the detection sensitivity and the reduction of the detection time, is obtained.

A first packing (first spacer)60is provided on the first substrate50(FIGS. 10 and 11B). The first packing60is provided with through the holes61,62, and63shown inFIG. 11Band the through hole64shown inFIG. 10.

Through holes61and62are positioned above the two circular groove areas. Through holes61and62are paths which introduce or collect the liquid into or from the groove51. Through hole63is positioned above the lower electrode21. Through hole64is positioned above the extraction electrode21a.

The first packing60is formed of, for example, an adhesive resin such as silicon rubber or PDMS, combination of a resin such as polyethylene terephthalate (PET) film and an adhesive agent applied thereon, or a combination of a resin such as PET film and a hydrophilic film applied thereto. With such a material, the first packing60is fixed on the first substrate50. The first packing60may be fixed on the first substrate50using an adhesive agent or an adhesive layer which is not shown. A forming method of the first packing44includes processing a member containing the above material by laser.

Subsequently, the partition3is provided on the first packing60, and then, a second packing (second spacer)70is provided on the first packing60(FIGS. 10 and 11C).

The second packing70is structured to cover an upper surface of an edge of the partition3, and the edge of the partition3is hold between the first packing60and the second packing70and thereby being fixed. The thickness of the second packing70is set to be thicker than the depth of the through hole4of the partition3, for example.

The second packing70is provided with the through holes71,72, and73shown inFIG. 11Cand the through hole74shown inFIG. 10.

Through holes71and72are positioned above through holes61and62. The through holes71and72, and together with the through holes61and62are used as the flow path to introduce or collect the liquid into or from the groove51. The through hole73is formed to be positioned on the partition3, and the through hole74is formed to be positioned above the extraction electrode21a.

A material of the second packing70is, for example, same as the material of the first packing60mentioned above. By using such a material, the second packing70can be fixed on the first packing60. In addition, the second packing70may be fixed on the first packing60by using an adhesive compound or adherent layer (not shown). The first packing and second packing may further have adhesiveness to the partition3. A forming method of the second packing70is same as the forming method of the first packing60.

The first substrate50, first packing60, and second packing70define the first chamber11ofFIG. 1.

Through holes81,82, and83and groove84are formed in a second substrate80(FIG. 10). The groove84is on the rear side of the second substrate80, and depicted by in a dotted line onFIG. 10. A material of the second substrate80is insulator, for example, resin that does not have conductive property such as polymethyl methacrylate, or glass. A method of forming the through holes81,82,83and the trench84is performed by, for example, applying laser processing, or physical process such as excavating to a member containing the above material.

After that, as shown inFIG. 11D, the upper electrode22is formed in the groove84, and the second substrate80is provided on the second packing70in a manner that the upper electrode22faces the second packing70. When the second packing70has adhesiveness, the second substrate80can be fixed on the second packing70. The second substrate80may be fixed on the second packing70by using an adhesive compound or adherent layer.

The through holes81, and together with the through holes71,72,61and62are used as the flow path to introduce or collect the liquid into or from the trench51(FIG. 11D).

The second packing70and the second substrate80define the second chamber12ofFIG. 1. The detection device ofFIG. 1corresponds to an area surrounded by the dotted line ofFIG. 11D.

InFIG. 11D, for example, after the first chamber is filled with the sample liquid by supplying the sample liquid from the through holes81,71and61(and/or through holes82,72and62), the second chamber can be filled with the non-sample liquid by supplying the non-sample liquid from the through holes81,71and61(and/or through holes82,72and62).

Note that, as shown inFIG. 12, by forming a second substrate80including another through hole85for supplying the non-sample liquid in addition to the through holes81,71and61for supplying the sample liquid, a mixture of the sample liquid and the non-sample liquid can be suppressed.

As can be understood from the above, the present embodiment allows provide the detection device, the detection method, and the electrode with the probe which are advantageous to increase the detection sensitivity and reduce the detection time, by employing the configuration to increase the concentration of the detection targets5in the vicinity of the fine hole4by using the probe23provided on the lower electrode21.

FIG. 13is a view schematically depicting a detection device according to a first variation of the present embodiment.

In the first variation, a variable power source31ais used instead of the direct current power source31, an electrode (seventh electrode)24is provided in the first chamber11, and a variable power source25is provided to supply a voltage to the electrode24. The electrode24is used to detach the probe23from the lower electrode21. A material of the electrode24is, for example, Pt. In the following description, the electrode24will be referred to as the separation electrode24. Note that, inFIG. 13, the separation electrode24is smaller than the lower electrode21; however, the size of the separation electrode24may be equal to the size of the lower electrode21.

In the first variation, for example, the probe23is detached from the lower electrode21as follows. A potential (V2) of the upper electrode22is set to zero by the variable power source31a, and a potential (V3) of the separation electrode24is set greater than a potential of the lower electrode21(V1) by the variable power source25. Since the sample liquid41is conductive, a current flows from the separation electrode24to the lower electrode21, and the probe23is detached from the lower electrode21.

Note that, when the detection target5is negatively charged, the probe23can be detached from the lower electrode21by setting V3>V1, V2, in general. Thus, V2 is not necessarily zero. However, in consideration of power consumption, V2 is, preferably, set to zero.

Furthermore, in the first variation, for example, the detection target5in the first chamber11is moved into the second chamber by electrophoresis as follows. When the detection target5is negatively charged, the potential (V2) of the upper electrode22is set greater than the potential (V1) of the lower electrode21by the variable power source31a, and the potential (V3) of the separation electrode24is set to zero by the variable power source25.

Note that, when the detection target5is negatively charged, the detection target5in the first chamber11can be moved into the second chamber12by electrophoresis by setting V3>V1, V2, in general. Thus, V2 is not necessarily zero. However, in consideration of power consumption, V2 is, preferably, set to zero.

FIG. 14is a view schematically depicting a detection device according to a second variation of the present embodiment.FIG. 15is a plan view illustrating a partition and a separation electrode of the detection device of the second variation.

In the first variation, the separation electrode24is provided on the lower surface side of the first chamber11, whereas in this second variation, the separation electrode24is provided with the upper surface side of the first chamber11. InFIG. 14, the separation electrode24is provided on the partition3in the first chamber11. In the second variation, when the detection targets are moved by electrophoresis, the potential difference between the electrodes21and24may be used.

FIG. 16is a view schematically depicting a detection device of a third variation of the present embodiment.

The third variation is different from the first variation in that the third variation further comprises a three-electrode system potentiostat26, and a reference electrode27. The potentiostat26has a reference pole, an action pole, and an opposing pole. The reference electrode27is disposed in the first chamber11. A material of the reference electrode27is, for example, AgCl.

The reference electrode27, the separation electrode24, and the lower electrode21are connected to the reference pole, the action pole, and the opposite pole of the potentiostat26, respectively. By using the potentiostat26, it is possible to accurately control the voltage between the lower electrode21and the separation electrode24. This enables an accurate separation of the lower electrode21from the probe23.

FIG. 17is a view schematically depicting a detection device according to a fourth variation of the present embodiment.

In the fourth variation, the potentiostat26is added to the second variation, and the separation electrode24is connected to the opposition pole of the potentiostat27.

Second Embodiment

FIG. 18is a view schematically depicting a detection device according to the second embodiment.

The present embodiment is different from the first embodiment in that two different kinds (plural kinds) of detection targets can be detected. In order to detect the two kinds of the detection targets, the detection device1of the present embodiment comprises two probes231and232, two through holes41and42, two upper electrodes221and222, two direct current power supply311and312, and two measurement circuit321and322.

The probe231(hereafter referred to as a first probe231) binds specifically to a first detection target, the probe232(hereafter referred to as a second probe232) binds specifically to a second detection target which is different from the first detection target.

The through hole41has a size (diameter) corresponding to the first detection target, and the through hole42has a size (diameter) corresponding to the second detection target. Hereafter, the through hole41and42may be described as fine holes41and42, respectively.

The through hole41is positioned below the upper electrode221. In addition, the through hole42is positioned below the upper electrode (fourth electrode)222. The upper electrodes221and222are disposed to face the lower electrode21.

The direct current power supply311and the measurement circuit321are connected with the upper electrodes221in series. Similarly, the direct current power supply312and the measurement circuit322are connected with the upper electrodes222in series.

A potential of the direct current power supply311may be same as or different from a potential of the direct current power supply312. That is, the potentials of the direct current power supplies311and312are selected such that the first detection target and the second detection target can be easily detected. In addition, when the potentials are the same, it is possible to employ a common direct current power supply as the two direct current power supplies311and312. When the potentials are different, the direct current power supply311and the direct current power supply312may be replaced with a single variable power supply.

The electrode (21,231,232) with the probes of the present embodiment can be formed, for example, by the following process.

After the lower electrode21is formed, a solution containing the first probe231is supplied on a partial region of the lower electrode21, and then a solution containing the second probe232is supplied on another partial region of the lower electrode21. The supply of the solution containing the first probe231, and the supply of the solution containing the second probe232are performed by, for example, using a screen printing technique, or an ink jet printing technique. By using such the technique, the solution containing the first probe231can be easily and selectively supplied on an arbitrary region of the lower electrode21, and similarly the solution containing the second probe232can be easily and selectively supplied on an arbitrary region of the lower electrode21.

Note that, the electrode (21,231,232) with the probes are also obtained by the forming method using the mask as in the first embodiment.

Now, a detection method using the detection device1of the present embodiment will be explained.

First, as shown inFIG. 19, the first chamber11is filled with the sample liquid41, and the second chamber122is filled with non-sample liquid42. The following description is given that the sample liquid41contains negatively charged detection targets51and52.

Since the first prove231binds specifically to the first detection target51; the concentration of the first detection target51is high in the vicinity of the fine through hole41. Similarly, since the second prove232binds specifically to the second detection target52, the concentration of the second detection target52is high in the vicinity of the fine through hole42.

Subsequently, a voltage is applied between the lower electrode21and the upper electrode221by the direct current power supply311, and a voltage is applied between the lower electrode21and the upper electrode222by the direct current power supply312.

As a result, as shown inFIG. 20, the first prove231and the first detection target51combined therewith are detached from the lower electrode21. Similarly, the second prove232and the second detection target52combined therewith are detached from the lower electrode21. In the following description, the first detection target51bound to the first probe231and the second detection target52bound to the second probe232may be simply referred to as the first detection target51and the second target detection52, respectively.

The first detection target51in the sample liquid41in the first chamber11moves into the non-sample liquid42in the second chamber12via the fine through hole41by electrophoresis (electric field). In response to the first detection target51passing through the fine hole41, the conductive state between the lower electrode21and the upper electrode221changes. Since the concentration of the first detection targets51is high in the vicinity of the fine hole41, the conductive state easily changes. Consequently, based on a time change of the current signal measured by the measurement circuit321, it is possible to determine whether the sample liquid41contains the first detection target51in a short time.

The second detection target52in the sample liquid41in the first chamber11moves into the non-sample liquid42in the second chamber12via the fine through hole42by electrophoresis (electric field). In response to the second detection target52passing through the fine hole42, the conductive state between the lower electrode21and the upper electrode222changes. Since the concentration of the second detection targets52is high in the vicinity of the fine hole42, the conductive state easily changes. Consequently, based on a time change of the current signal measured by the measurement circuit322, it is possible to determine whether the sample liquid41contains the second detection target52in a short time.

Note that, the time of applying the voltage between the lower electrode21and the upper electrode221may be different from the time of applying the voltage between the lower electrode21and the upper electrode222. For example, when the potential to be applied to the lower electrode21is different from the potential to be applied to the upper electrode221, and the direct current power sources31and93are replaced with the single variable power supply, the two voltages are applied at different times.

Further, in the present embodiment, as shown inFIG. 18, the plurality of first probes231are disposed on the left side of the lower electrode21, and the plurality of the second probes232are disposed on the left side of the upper electrode22. However, all of, or a part of the plurality of the first probes231and the plurality of the second probes232may be disposed to mix on the lower electrode21.

Furthermore, the number of the plurality of the first probes231and the number of plurality of the second probes232may be the same or may be different. The dimensions of the upper electrode221and the dimensions of the upper electrode222may be same or may be different.

In accordance with the detection device and the detection method to detect two kinds of detection targets of the present embodiment, a detection device and a detection method to detect three or more detection targets can be achieved.

In addition, in the present embodiment, the first probe231and the second probe232are configured to bind specifically to the different kinds of the detection targets, respectively, however, the first probe231and the second probe232may be configured to bind specifically to the same kind of the detection target. That is, the detection device and the detection method of the present embodiment is also applicable to the detection device and the detection method which are directed to a single kind of detection target.

Third Embodiment

FIG. 21shows a schematic view of a detection device1of the third embodiment.

The present embodiment is different from the second embodiment in that the present embodiment comprises two (plural) lower electrodes211and212.

The first probe231is detachably connected to the lower electrode211, and the second probe232is detachably connected to the lower electrode (third electrode)212.

The upper electrode221is disposed to face the lower electrode211, and the upper electrode222is disposed to face the lower electrode212.

A through hole41is positioned between the lower10. electrode211and the upper electrode221, and a through hole42is positioned between the lower electrode212and the upper electrode222.

Now, a detection method using the detection device1of the present embodiment will be explained.

First, as shown inFIG. 22, the first chamber11is filled with the sample liquid41, and the second chamber12is filled with the non-sample liquid42.

Since the first probe231binds specifically to the first detection target51, the concentration of first detection targets51becomes high in the vicinity of the fine hole41. Similarly, since the second probe232binds specifically to the second detection targets52, the concentration of second detection targets52becomes high in the vicinity of the fine hole42.

Subsequently, a voltage is applied between the lower electrode211and the upper electrode221by using a direct current power supply311, and a voltage is applied between the lower electrode212and the upper electrode222by using a direct current power supply312.

As a result, as shown inFIG. 23, the first probe231and the first detection target51combined therewith are detached from the lower electrode211. Similarly, the second probe232and the second detection target52combined therewith are detached from the lower electrode212.

The first detection target51in the sample liquid41in the first chamber11moves into the non-sample liquid42in the second chamber12through the fine hole41by electrophoresis (electric field). When the first detection target51passes through the fine hole41, a conductive state between the lower electrode211and the upper electrode221changes. Since the concentration of first detection targets51is high in the vicinity of the fine hole41, the conductive state easily changes. Consequently, based on a time change of the current signal measured by the measurement circuit321, it is possible to determine whether the sample liquid41contains the first detection target51in a short time.

The second detection target52in the sample liquid41in the first chamber11moves into the non-sample liquid42in the second chamber12through the fine hole42by electrophoresis (electric field). When the second detection target52passes through the fine hole42, a conductive state between the lower electrode212and the upper electrode222changes. Since the concentration of second detection targets52is high in the vicinity of the fine hole42, the conductive state easily changes. Consequently, based on a time change of the current signal measured by the measurement circuit322, it is possible to determine whether the sample liquid41contains the first detection target52in short time.

In the present embodiment, the lower electrode211and the lower electrode212are physically different. Thus, the lower electrode211is easily optimized with respect to the first probe231and the lower electrode212is easily optimized with respect to the second probe232. For example, it is possible to use the lower electrode211containing a material and/or having a plane direction which is suitable to easily detach the first probe231from the lower electrode212, and the lower electrode212containing a material and/or having a plane direction which is suitable to easily detach the second probe232from the lower electrode212.

A forming method of the lower electrodes211and212is, for example, same as the forming method of the lower electrode of the first embodiment.

As with the second embodiment, the detection device and the detection method of the present embodiment is applicable to a detection device and a detection method which are directed to detect three or more kinds of detection targets, and a detection device and a detection method which are directed to detect a single kind of detection target.

Fourth Embodiment

FIG. 24is a view schematically depicting a detection device according to the fourth embodiment.

The detection device1of the present embodiment includes a first chamber11of a flow passage structure. A sample liquid (not shown) introduced into the first chamber11flows in a left-to-right direction6, for example. As a result, the detection target (not shown) in the sample liquid flows in the left-to-right direction6, thereby reducing time required for the detection target to combine with the probe23. The flow passage structure of the present embodiment is applicable to the first to third embodiments, too.

The flow of the sample liquid can be generated by transferring liquid by using a pump (not shown). Alternatively, the flow of the sample liquid can be generated by providing a absorption band on the downstream (channel downstream) side of the sample liquid in the chamber11to cause the sample liquid to be absorbed in the absorption band. A flow speed of the sample liquid is appropriately changed in a range of 0.001 to 1000 μL/min, for example.

The detection device1of the present embodiment is different from the first to third embodiment further in that the detection device1includes a guide mechanism to guide the detection target in the sample liquid to the probe23.

The guide mechanism includes a lower guide electrode (fifth electrode)91, an upper guide electrode (sixth electrode)92, and a direct current power supply93. The lower guide electrode91is provided on a bottom surface of the first chamber11in a similar way as the lower electrode21. The lower guide electrode91is grounded. The lower guide electrode91is disposed apart from the lower electrode21by a constant distance.

The upper guide electrode92is provided on the upper surface in the first chamber11and is connected to the direct current power source93. The upper guide electrode92is disposed apart from the partition3by a constant distance such that the upper guide electrode92faces the lower guide electrode91.

Note that, the direct current power supply31and the direct current power supply31may be changed to a single variable power supply. A material of the lower guide electrode91and a material of the upper guide electrode92are, for example, same as the material of the lower electrode21.

Now, a detection method using the detection device1of the present embodiment will be explained.

First, as shown inFIG. 25, the second chamber12is filled with the non-sample liquid42, and the first chamber11is filled with the sample liquid41. The following description is given that the sample liquid41contains negatively charged detection targets5.

A positive potential is applied to the lower guide electrode91and a negative potential is applied to the upper guide electrode92by using the direct current power source93. As a result, electrical flux lines are generated from the lower guide electrode91to the upper guide electrode92. At that time, the direct current power source31is off, and there is not a potential difference between the lower electrode21and the upper electrode22.

Since the detection target5is negatively charged, downward force due to the electrical flux lines acts on the detection target5moving from left to right. As a result, the direction of movement of the detection target5is changed such that the detection target5moves closer to the probe23on the lower electrode21.

In this way, by guiding the detection target5to come closer to the probe23(guiding process), the status shown inFIG. 4, that is, the detection target5is bound to the probe23, can be easily achieved. After the guiding process is performed for a predetermined period of time, the direct current power supply93is switched off and the flow of the sample liquid41is stopped.

After that, similarly to the first embodiment, the voltage is applied between the lower electrode21and the upper electrode22by the direct current power supply31to detached the probe23from the lower electrode21, and the determination of the presence or absence of the detection target5is performed by the measurement circuit32.

FIG. 29is a view schematically depicting a detection device of a variation of the present embodiment. In this variation, the upper guide electrode92is provided in the second chamber12. More specifically, the upper guide electrode92is provided on the lower surface (bottom) in the second chamber12.

The lower surface in the second chamber12(upper surface in the first chamber) is defined by the film75shown inFIG. 26C. Since the film75is thin, a potential difference can be applied between the lower guide electrode91and the upper guide electrode22by the direct current power supply93. As a result, the electrical flux lines mentioned above are generated, and the detection targets can be guided the near the probe23.

In addition, the sample liquid is not flown in the second chamber12, and thus the probe32is not required to be provided on the upper guide electrode92in the second chamber12.

FIGS. 26A to 26Dare plan views for explaining a manufacturing method of the detection device1of the present embodiment.

First, as shown inFIG. 26A, the lower electrode21and the extraction electrode21athereof, and the lower guide electrode91and a extraction electrode91athereof are formed on the first substrate50. The first substrate50defines the bottom surface (bottom of the flow passage) of the first chamber11.

A length101of the lower guide electrode91is, for example, 5 mm, and a length102of the lower electrode21is, for example, 1 mm. The lower guide electrode91and the lower electrode21have a width of, for example, 1 mm.

Subsequently, as shown inFIG. 26B, a packing (spacer)60is formed. The packing60defines a side surface (flow passage wall) of the first chamber11. In the present embodiment, the packing60is given adherence.

The packing60is provided with through holes61aand62acorresponding to the through holes61and62(FIGS. 10 and 11B) of the first embodiment. The packing60is further provided with a through hole65corresponding to the flow passage ,and a through hole66to extract the extraction electrode91a. The through hole65is formed to connect the through hole61aand the through hole62a, and the through holes61a,62aand65constitute a single through hole. A width of the through hole65defining the flow passage width is, for example, 1 mm, and the thickness of the packing60defining the flow passage height is, for example, 25 μm.

Subsequently, as shown inFIG. 26C, a film (thin film)75is formed. The film75is provided with a through hole61a′ and a through hole61b′. The through hole61a′ and the through hole61b′ communicate with the through hole61aand the through hole61bof the packing60, respectively. The through hole61a′ and the through hole61b′ constitute the flow passage. Similarly, the through hole62a′ and the through hole61b′ constitute the flow passage. The film75defines the upper surface in the first chamber11and the lower surface in the second chamber12.

The film75is provide with a through hole76corresponding to the through hole4of the partition3, a through hole77to extract extraction electrode21a, and a through hole78to extract extraction electrode91a.

Subsequently, as shown inFIG. 26D, the upper guide electrode92and the extraction electrode92athereof are formed on the film75. A adhesive member (for example, adhesive layer or adhesive agent)79, and then the partition3is placed on the adhesive member79, thereby fixing the partition3on the film75. At this time, the partition3is fixed on the film75such that the through hole4of the partition3communicates with the through hole76of the film7. The through hole76is generally larger than the through hole4.

Subsequently, as shown inFIG. 26A, the packing60inFIG. 26Bis fixed on the first substrate50inFIG. 26A.

Thereafter, the film75inFIG. 26Dis fixed on the packing60. The cross-sectional view of the structure in this stage is shown inFIG. 27. The cross-sectional view inFIG. 27corresponds to a cross-section along the21-21line inFIG. 26D.

Subsequently, a structure including the second chamber12and the upper electrode22is formed in accordance with a well-known method. After that, the direct current power supply31and the measurement circuit32are connected to the upper electrode22in series, and the direct current power supply93is connected to the upper guide electrode92.

Note that, the order of processes shown inFIGS. 26A to 26Dcan be appropriately changed. For example, the process ofFIG. 26Bmay be before the process ofFIG. 26A, or after the process ofFIG. 26D.

FIG. 28is a view schematically depicting a detection device1of a first variation of the present embodiment. In this variation, a probe34for suppressing the detection target from being adsorbed specifically to the lower guide electrode91.

The probe34includes, for example, thiol molecule whose one end is connected to the lower guide electrode91and other end is an OH group. That is, the probe34includes, for example, a structure in which the second part23-2ofFIG. 3is replaced with the OH group. The OH group is exposed on the surface of the lower guide electrode91. Since the OH group is hydrophilic, the OH group is effective in suppressing the adsorption of the detection target5.

Note that, both of the lower guide electrode91and the upper guide electrode92may be provided with the probes34. The probe34(functional group) that is provided to the lower guide electrode91may be same as or different from the probe34(functional group) that is provided to the upper guide electrode92. In addition, the probe34may be provided to the upper guide electrode92alone.

FIG. 29is a view schematically depicting a detection device1according to a second variation of the present embodiment. In the second variation, the upper guide electrode92is provided in the second chamber12. More specifically, the upper guide electrode92is provided on lower surface (bottom) in the second chamber12.FIG. 30is a cross-sectional view illustrating a structure in a process of manufacturing the detection device1according to the second variation, which corresponds to cross-sectional view ofFIG. 27. In the second variation, the upper guide electrode92is formed on a first plane (surface) of the film75, and the adhesion member79and the partition3are formed on the opposite plane (rear surface) side of the first plane of the film75.

The lower surface in the second chamber12(upper surface of the first chamber) is defined by the film75shown inFIG. 26C. Since the film75is thin, a differential potential can be applied between the lower guide electrode91and the upper guide electrode92by the direct current power source93. As a result, the electrical flux lines mentioned above are generated, and the detection target can be guided near the probe23.

In addition, since the detection liquid is not flown in the second chamber12, the probe34is not required to be provided on the upper guide electrode92in the second chamber12.

FIG. 31is a view schematically depicting a detection device1according to a third variation of the present embodiment. In the third variation, the partition3and the upper guide electrode92are provided in the second chamber12. More specifically, the partition3and the upper guide electrode92are provided on the lower surface (bottom) in the second chamber12.FIG. 32is a cross-sectional view illustrating a structure in a process of manufacturing the detection device1according to the third variation, and corresponds to cross-sectional view ofFIG. 27. In the third variation, the upper guide electrode92, the adhesive member79, and the partition3is formed on the surface side of the film75.

FIG. 33is a view schematically depicting a detection device1according to a fourth variation of the present embodiment. In the fourth variation, the upper guide electrode92is provided in the first chamber11, and the partition3is provided in the second chamber12. More specifically, the upper guide electrode92is provided on the upper surface in the first chamber11, and the partition3is provided on the lower surface in the second chamber12.FIG. 34is a cross-sectional view illustrating a structure in a process of manufacturing the detection device1according to the fourth variation, and corresponds the cross-sectional view ofFIG. 27. In the fourth variation, the adhesive member79and the partition3are formed on the surface side of the film75, and the upper guide electrode92is formed on the rear surface side of the film75.