WO2004105153A2

WO2004105153A2 - Micro/nano fluidic 3-dimensional electrode system

Info

Publication number: WO2004105153A2
Application number: PCT/KR2004/001194
Authority: WO
Inventors: Je-Kyun Park; Yu-Heon Yi; Seung-Joo Kang
Original assignee: All Medicus Co., Ltd; Korea Advanced Institute Of Science And Technology
Priority date: 2003-05-23
Filing date: 2004-05-21
Publication date: 2004-12-02
Also published as: KR100563834B1; KR20040100646A; WO2004105153A3

Abstract

The present invention discloses a three-dimensional electrode system having an integrated micro/nano fluidic channel. The three-dimensional electrode system comprises a first dielectric substrate, a second dielectric substrate facing the first dielectric substrate with a predetermined gap in-between, a plurality of oxidation electrodes formed on the first dielectric substrate, and a plurality of reduction electrodes formed on the second dielectric substrate. A micro/nano fluidic channel is formed between the first and second dielectric substrates. The oxidation and reduction electrodes are formed in predetermined intervals along the micro/nano fluidic channel and substantially perpendicular to the micro/nano fluidic channel. The electrodes are electrically interconnected. A bio-fluidic flows through the micro/nano fluid channel in zigzags, not straight, such that mixing of the fluid can be facilitated, and oxidation and reduction reactions of electroactive species contained in the fluid can be electrochemically analyzed with a high degree of efficiency.

Description

MICRO/NANO FLUIDIC 3-DIMEMSIONA ELECTRODE SYSTEM

Technical Field

The present invention relates to a three- dimensional electrode system where a micro/nano fluidic channel is integrated. Particularly, the invention can be employed as an electrochemical detector in a biochip such as protein chip and DNA chip, a micro/nano fluidic device, a lab-on-a-chip, high performance liquid chromatography (HPLC), and flow injection analysis (FLA) system, etc.

Background Art

In a nano-scale blood analysis system for the medical use, all the components required for sample analysis should be integrated in a unit chip by using micro/nano electromechanical systems so that a few nano- liters of fluid sample can be treated in such a tiny unit chip, in connection with micro/nano fluidics. However, conventional detection technologies have utilized mainly optical methods applied to an external analyzer and thus it has been an obstacle to construct a nano-scale bioanalytical device. Especially, in order to analyze biomolecules which exist in a small quantity relative to that of a blood sample, it is very important to selectively identify and detect only desired biomolecules with a high degree of sensitivity, and to pretreat the sample to remove interference substances which may cause a negative effect during the analysis. The DNA chip or protein chip, which has been recently developed and extensively researched, is desired to take in a portable biosensor form so that it can be used in on-site analysis in order to apply to medical diagnoses, environmental and food monitoring sensors. For example, the protein chip using antigen-antibody i munoreaction occasionally requires a step of removing the substances not involved in the immunoreaction. A series of analysis steps such as reaction and cleaning, etc., may not serve as a critical impediment in the course of research of protein chip, but these pretreatment procedures should be automated and simplified in order to commercialize the protein chip. Therefore, micro-TAS (micro total analysis system) concept has been developed, which has been implemented in a chip and called a lab-on-a-chip. Among others, the micro/nano fluidics and detection technologies are very important in the research of the lab-on-a-chip.

In the micro/nano fluidics, there are provided a circuit of micro/nano fluidic channels on the surface of plastic, glass or silicon substrate such that a series of steps of sample pretreatment, analysis, dilution, mixing, biochemical reaction and detection, etc., can be integrated in a tiny single chip. Especially, the micro/nano fluidic control of biomolecules is a core technology in a sequential pretreatment and analysis of a fluid sample.

On the other hand, one of the detection technologies, which can be advantageously implemented in the lap-on-a-chip, is the electrochemical detection method since it allows for miniaturization and simplification of measuring devices. Among semiconductor type biosensors is an interdigitated array (IDA) electrode where metallic electrodes of a finger shape are overlapped with a micro/nano gap in-between and thus electrochemical reactions can be sequentially carried out. The interdigitated array electrode is designed to be able to detect the conductivity change caused by enzyme reaction and the sequential reactions of oxidation and reduction of electroactive species so that it may be favorably utilized in the development of electrochemical biosensors and biochip detectors (Biosensors and Bioelectronics 9: 697-705, 1994). Especially, the immunosensor and protein chip using antigen-antibody reaction can determine the quantity of antigen (or antibody) by measuring the physical and chemical change associated with the immunoreactions . In order to electrochemically detect the process of antigen-antibody reaction, enzyme or electroactive species may be provided as a label substance to the antigen or antibody and their relative activities can be measured before and after the immunoreaction. See Anal. Chem. 65: 1559-1563, 1993. However, with the conventional IDA electrodes having a two-dimensional (planar) structure, it is difficult to integrate micro/nano fluidic channels therewith for the construction of a lap-on-a-chip or an analyzer system such as FIA system and HPLC (Anal. Chi . Acta 326: 155- 161, 1996; Sensors and Actuators B49: 73-80, 1998; Sensors and Actuators B71: 82-89, 2000).

The nanobiotechnology is the core of the medical nano-system for blood analysis in that it provides for enhancement in the sensitivity of the sensors by means of efficient detection principles, painless blood sampling, and micro/nano fluidics for treating a small quantity of fluid sample, thereby enabling the nano-scale operation of a single biomolecule.

The conventional IDA electrode structures have two kinds of working electrodes on a two-dimensional substrate such that the electrodes can measure oxidation and reduction reactions, which results in various disadvantages and problems. That is, the conventional IDA electrode requires an additional flow-through cell on the surface of the electrodes to contact bio-fluid to the sensing portion of the sensor, and there is, therefore, a limitation in implementing the flow-through cell and the sensing portion together on top of a lap-on-a-chip. It has low efficiency in detecting oxidation and reduction current of the electroactive species contained in a small quantity of bio-fluid sample. Due to the low sensitivity of the conventional IDA electrode, it is inappropriate for applying to the electrochemical detection system of a lap-on-a-chip, which is designed to deal with a few nano- liters of fluid. There is a limitation in the automation of sample injection and cleaning process by a buffer solution, as required in the immunoreaction measuring system. Disclosure of Invention

It is an object to provide an electrode system in which a nano-scale IDA electrode and a micro/nano fluidic channel can be integrated together. A further object of the invention is to provide an electrode system where the oxidation and reduction reactions of electroactive species can be detected with a high degree of efficiency, thereby generally enhancing the sensitivity of sensors. A further object of the invention is to provide a three-dimensional IDA electrode structure that can be advantageously employed in a lap-on-a-chip in which the sample pretreatments are integrated therein.

In the three-dimensional IDA electrode system designed to achieve the above objects of the invention, an anodic IDA electrode and a cathodic IDA electrode are faced to each other and spaced apart with a gap of nano- scale in-between such that a macro/nano fluidic channel can be formed between the anodic and cathodic electrodes. The three-dimensional IDA electrode structure of the invention comprises a first and second working electrodes that are served as an anode and a cathode respectively which can be fabricated by means of conventional thick- film and thin film processes. The anodic and cathodic electrodes are arranged respectively on both sides of the micro/nano fluidic channel and encountered alternately along the channel such that they are faced to each other in zigzags. The inlet and outlet of the micro/nano fluidic channel are structured to be able to be connected to that of a lap-on-a-chip. In order for the three- dimensional IDA electrode system to be employed as an electrochemical measurement system, in addition to the working electrodes, a reference electrode and a counter electrode may be provided on the inlet or outlet of the electrode system, thereby establishing a three-electrode system. Alternatively, a two-electrode system may be established by providing the reference electrode only.

According to the present invention, there is provided a three-dimensional electrode system in which a micro/nano fluidic channel is integrated. The three- dimensional electrode system comprises a first dielectric substrate, a second dielectric substrate facing the first dielectric substrate with a predetermined gap in-between wherein a micro/nano fluidic channel is formed between the first and second dielectric substrate, a plurality of oxidation electrodes formed on the first dielectric substrate in predetermined intervals along the micro/nano fluidic channel and substantially perpendicular to the micro/nano fluidic channel, and a plurality of reduction electrodes formed on the second dielectric substrate in predetermined intervals along the micro/nano fluidic channel and substantially perpendicular to the micro/nano fluidic channel. The respective oxidation and reduction electrodes are electrically inter-connected.

Preferably, the oxidation and reduction electrodes are arranged respectively on both sides of the micro/nano fluidic channel and encountered alternately along the channel in zigzags. The oxidation and reduction electrodes have a predetermined thickness, thereby providing prominent and depressed portions to the first and second dielectric substrates. The fluid flowing through the micro/nano fluidic channel encounters in zigzags the oxidation and reduction electrodes, and oxidation and reduction reactions of the fluid are alternately repeated. The fluid flowing through the micro/nano fluidic channel contains electroactive species. The oxidation and reduction electrodes are spaced apart with a gap of nano-scale in-between.

According to the present invention, there is provided a three-dimensional electrode system in which a micro/nano fluidic channel is integrated. The three- dimensional electrode system comprises a first conductive substrate, a second conductive substrate facing the first conductive substrate with a predetermined gap of nano- scale in-between wherein a micro/nano fluidic channel is formed between the first and second conductive substrate, a plurality of first dielectric members formed on the first conductive substrate in predetermined intervals along the micro/nano fluidic channel and substantially perpendicular to the micro/nano fluidic channel; and a plurality of second dielectric members formed on the second conductive substrate in predetermined intervals along the micro/nano fluidic channel and substantially perpendicular to the micro/nano fluidic channel.

In the three-dimensional electrode system of the invention described above, the flow of electroactive species through the micro/nano fluidic channel occurs in zigzags, not straight, so that the zigzag flow pattern can facilitate mixing effect of bio-fluid flowing through the channel. In a micro/nano fluidic device fabricated according to the invention, the gap between the two electrodes may be varied in order to control the velocity, quantity, flow pattern and mixing of the bio-fluid, and the efficiency of current measurement from electroactive species. The oxidation and reduction reaction of the electoactive species can be measured with a high degree of efficiency by using the electrochemical methods such as the chronoamperometric method or the conductivity measurement technique. The three-dimensional IDA electrode system of the invention can be mass-fabricated by means of a collective and continuous operation of the semiconductor process. The system of the invention may be employed as an electrochemical detector in a biochip such as protein chip and DNA chip, a micro/nano fluidic device, a lap-on-a-chip, high performance liquid chromatography, and a flow injection analysis system, etc.

Brief Description of Drawings

Further objects and advantages of the invention can be more fully understood from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a perspective view of a three-dimensional IDA electrode system according to one embodiment of the invention, in which metallic electrodes are deposited on a dielectric substrate; FIG. 2 illustrates a cross-sectional perspective view taken along the line A-B in FIG. 1;

FIG. 3 shows a cross-sectional view taken along the line A-B in. FIG. 1; FIG. 4 is a perspective view of a three-dimensional IDA electrode system according to another embodiment of the invention, in which dielectric pattern is deposited on a conductive substrate;

FIG. 5 shows a cross-sectional perspective view taken along the line A-B in FIG. 4;

FIG. 6 illustrates a cross-sectional view taken along the line A-B in FIG. 4;

FIG. 7 is an exploded perspective view of the manufacturing process of the invention before a first and second dielectric substrates are attached; and

FIG. 8 is a perspective view of the three- dimensional IDA electrode system completed according to the invention.

Best Mode for Carrying Out the Invention

Referring to the accompanying drawings, the embodiments according to the present invention are described in detail hereafter. The same reference numerals are used in different figures to denote similar or identical components .

FIG. 1 is a perspective view of a three-dimensional electrode system according to one embodiment of the invention where a metallic electrodes is disposed on a dielectric substrate, and FIG. 2 shows a cross-sectional perspective view taken along the line A-B in FIG. 1. As shown in FIG. 1, the three-dimensional electrode system, in which micro/nano fluidic channel is integrated, comprises two dielectric substrates 1, a plurality of reduction electrodes 2, and a plurality of oxidation electrodes 3. In the description, the "oxidation electrode" denotes an electrode in which electroactive species are oxidized, and the "reduction electrode" means an electrode where the electroactive species are reduced. The two dielectric substrates 1 are faced to each other with • a certain gap in-between to form a micro/nano fluidic channel. The oxidation electrodes 3 are formed on one of the two dielectric substrates 1 in predetermined intervals along and substantially perpendicular to the micro/nano fluidic channel. The oxidation electrodes 3 are electrically inter-connected. The reduction electrodes 2 are formed on the other one of the two dielectric substrates 1 in desired intervals along and substantially perpendicular to the micro/nano fluidic channel. The reduction electrodes are electrically inter-connected. As shown in FIGs. 1 and 2, the oxidation and reduction electrodes 2 , 3 are arranged respectively on both sides of the micro/nano fluidic channel and encountered alternately in zigzags. The electrodes 2 and 3 have a certain thickness and thus provide prominent and depressed portions on the surface of the dielectric substrates 1. Also, the respective oxidation and reduction electrodes 2 ■ and 3 are spaced apart with a gap of nano-scale therebetween. The two dielectric substrates 1 are etched such that the prominent and depressed portions are alternatively repeated. Then, the prominent portions are deposited with a conductor material to provide working electrodes 2 and 3 (also referred to as the "oxidation and reduction electrodes"). In FIG. 3, The upper working electrode may serve as an anode to oxidize the electroactive species, and the lower working electrode may serve as a cathode to ^'deoxidize the electroactive species, and vice versa.

FIG. 3 illustrates a cross-section taken along the line A-B in FIG. 1. As shown in FIG. 3, the fluid flowing through the micro/nano fluidic channel encounters alternately the oxidation and reduction electrodes 2 and 3 in zigzags, and thus oxidation and reduction reactions are alternately repeated. The fluid flowing in the micro/nano fluidic channel contains electroactive species. As illustrated in FIG. 3, while the fluid flows along the top plane of the electrodes 2 and 3, the oxidation and reduction reactions occur in the electroactive species alternately at the anodic working electrode 3 and the cathodic working electrode 2 respectively.

For example, the enzyme, called alkaline phosphatase which is frequently used for immunoassays, produces an electroactive species, called p-aminophenol based on p-aminophenyl phosphate. By electrochemically measuring the quantity of the p-aminophenol produced, antigen-antibody reaction can be quantitatively analyzed. This is, when relative to a reference electrode a voltage of about 250 V applies to the anodic working electrode 3, the p-aminophenol is oxidized to produce quinoneimine . The produced quinoneimine is reduced to produce p- aminophenol at the cathodic working electrode 2 to which a voltage of about -50 mV is applied, relative to the ■reference electrode. Consequently, while the p- a inophenol flows through the fluidic channel formed in the three-dimensional IDA electrode system, the sequential reaction of oxidation and reduction increases the current value, which results in signal amplification with a high degree of sensitivity.

Similarly, most organic compounds, as long as they can carry out oxidation and reduction reactions at the electrodes, may be used as an electroactive species for the three-dimensional IDA electrode system. For example, the electroactive species, which can be used in the three-dimensional IDA electrode system, include ferrocene, ferrocene derivatives such as dimethylferrocene, potassium ferricyanide, viologen derivatives, DCPIP(2,6- dichlorophenolindophenol) , TTF (tetrathiafulvalene) , TCNQ (tetarcyanoquinodimethane) , PMS (phenazine methosulphate) , Meldola ' s Blue (7-dimethylamino-l, 2-benzophenoxazine, BPO (1, 2-benzophenoxazine-7-one) , and thionin. Therefore, in all the biochemical analysis associating these electroactive species, the biochemical substances may be electrochemically measured by using the three-dimensional IDA electrode system of the invention.

According to the invention, the three-dimensional IDA electrode system where micro/nano fluidic channel is integrated may be embodied in a thin-film form by depositing gold electrodes on a glass or silicon substrate, and a micro/nano fluidic channel may be automatically formed between the electrodes, simultaneously while manufacturing the three-dimensional electrode structure. Therefore, miniaturization and mass-production of the detector system can be realized, without the necessity of making and combining an additional flow cell. The three-dimensional electrode system of the invention may be expected to be distinguished from the conventional analyzer system, in the aspect of improvement in the measuring sensitivity. This is, dissimilar to the conventional IDA electrode structures, the electroactive species contained in bio-fluid can be measured with a high degree of efficiency according to the present invention. Therefore, reproduction of measurement can be readily realized, and a small quantity of sample can be easily applied in both a static and flowing mode of the electrode system of the invention. The electrode system of the invention can overcome detection limit, which has been a significant problem in the conventional electrochemical analysis.

The three-dimensional IDA electrode system having a micro/nano fluidic channel may make it possible to fabricate a nano-scale sensing part for medical blood- analysis. Therefore, due to efficient signal amplification, a micro quantity of protein and non- protein substance can be analyzed, and consequently a high sensitivity of detection can be realized using a small quantity of sample as required in the micro-scale analyzer system. Integration of detection elements is most important in the development of nano-scale blood analyzers. The nano-scale IDA electrodes of the invention and the electrochemical analysis thereof allows for the integration of those detecting elements, and thus makes a great contribution to the realization of a blood analyzing lap-on-a-chip, which carries out a series of analyzing steps including biochemical reaction and cleaning of blood samples .

FIG. 4 schematically depicts a three-dimensional IDA electrode system according to another embodiment of the invention, in which a dielectric pattern is disposed on a conductive substrate. FIG. 5 is a cross-sectional perspective view taken along the line C-D in FIG. 4 and FIG. 6 illustrates a cross-section taken along the line C-D in FIG. 4. As shown in FIGs. 4, 5 and 6, the three- dimensional electrode system of this embodiment comprises a first conductive substrate 5 and a second conductive substrate 6, which face each other with a gap of nano- scale to form a micro/nano fluidic channel. A dielectric structure 7 is provided substantially perpendicular to the first and second conductive substrate 5 and 6 respectively. In this embodiment, the portions of the conductive substrates 5 and β exposed by means of the dielectric structure 7 serve as working electrodes.

As shown in FIG. 5, the dielectric structures 7 of the first and second conductive substrate alternate along the micro/nano fluidic channel in zigzags. Also, the dielectric structures have a certain predetermined thickness to provide prominent portions and depressed portions to the first and second conductive substrates 5 and 6.

Similar to the first embodiment shown in FIG. 1 to 3, the oxidation of electroactive species occurs, for example, at the second conductive substrate 6 which serves as an anodic working electrode, and the reduction of electroactive species occurs at the first conductive substrate 5 which serves as a cathodic working electrode. In the three-dimensional IDA electrode system shown in FIGs. 1 to 3, a dielectric layer 4 is provided along the fluidic channel on both sides of the electrode. In the first embodiment of FIGs. 1 to 3, the thickness of the electrodes 2 and 3 or the dielectric layer 4 may be varied such that bio-fluid can flow through the fluidic channel in zigzags, thereby being able to efficiently repeat the oxidation and reduction reactions at the anodic and cathodic electrodes, which are alternately encountered by the fluid. In the second embodiment shown in FIGs. 4 to 6, by varying the thickness of the dielectric structures 7 or the gap between the conductive substrates 5 and 6, the zigzag flow pattern can be controlled to carry out efficient oxidation and reduction reactions at neighboring electrodes.

Referring to FIGs. 7 and 8, the manufacturing process of the electrode system of the invention is described in detail. FIG. 7 is an exploded perspective view of the process before a first and second dielectric substrates are attached. FIG. 8 depicts a perspective view of the three-dimensional IDA electrode system completed according to the invention. Firstly, a silicon wafer 8 of single crystal having a thickness of about 500 μm is dried in the convector oven at 200 °C for about 30 minutes. A silicon oxide film of about 1 μm thickness is chemically deposited on the silicon wafer at about 1100 °C for 2 hours by using an oxide-film deposition furnace. The silicon wafer is maintained, with one or two drops of HMDS in an oven at 120 °C for about 3 minutes to facilitate contact with photoresist (PR) . Then, a positive photoresisitor (for example, Shipley 1827) is spin-coated on the treated silicon wafer at 1000 rpm for 5 seconds and then at 7000 rp for 35 seconds. The above wafer is maintained in the oven at 90 ^°C for 20 minutes to slightly cure the photoresistor . The above-treated wafer is exposed to ultraviolet beam for 15 seconds by using Kasper Contact Mask Aligner. By dipping the wafer in chlorobenzene solution, the exposed portion is undercut during development and step-coverage characteristics are deteriorated. The exposed photoresistor is removed after developing using MF319 solution. After the development, the silicon wafer is thoroughly rinsed with distilled water and dried by blowing nitrogen gas. A gold coat is evenly applied on the treated wafer by using a sputter. By dipping the wafer in acetone for 5 minutes, the remaining photoresistor is dissolved and the gold coat is remained only on the previously developed portion to form a first gold electrode 9 in FIGs. 7 and 8. Then, A photoresistor, called AZ9260 which allows for a coat of high thickness, is spin-coated on the wafer at a thickness of about 14 μm at 1500 rpm, and the coated wafer is soft-baked in a convector oven at 110 ^°C for 80 seconds. The above- treated wafer is covered with a mask and exposed to ultraviolet beam after aligning by using Ultratech stepper model 1500. Thereafter, the exposed wafer is developed using AZ400K solution and then a spacer 10 is fabricated in order to make the electrodes in a three- dimensional structure. Using the same procedures as in first gold electrode 9, a second gold electrode 11 is printed. Then, the spacer 10 made of photoresistor is removed to form a channel surrounded by the electrodes. Since the second gold electrode is very thin and long, it can be easily collapsed by external impact. Therefore, before removing the spacer shown in FIG. 7, polydimethylsiloxane (PDMS) is poured evenly on the second gold electrode and cured to produce a protective layer 12 by maintaining in an oven at about 80 ^°C for around 1 hour. After the PDMS is sufficiently cured, the wafer is immersed in AZ400T or AZ300T solution to remove the spacer photoresistor completely. The finished three- dimensional electrode system is rinsed with acetone and ethanol. The packaging of the electrodes is carried out by using a connection pad made of a printed circuit board. An electrochemical cleaning procedure is carried out by repeating cyclic voltammetry in a solution of 1 M H₂S0₄.

Industrial Applicability

While the present invention has been described with reference to the particular illustrative embodiments, it is not to be restricted by the embodiments but only by the appended claims. It is to be appreciated that those skilled in the art can change or modify the embodiments without departing from the scope and spirit of the present invention.

Claims

What Is Claimed Is:

1. A three-dimensional electrode system in which a micro/nano fluidic channel is integrated, the three- dimensional electrode system comprising: a) a first dielectric substrate; b) a second dielectric substrate facing the first dielectric substrate with a predetermined gap in-between wherein a micro/nano fluidic channel is formed between the first and second dielectric substrate; c) a plurality of oxidation electrodes formed on the first dielectric substrate, the oxidation electrodes being . formed in predetermined intervals along the micro/nano fluidic channel and being substantially perpendicular to the micro/nano fluidic channel, wherein the oxidation electrodes are electrically interconnected; and d) a plurality of reduction electrodes formed on the second dielectric substrate, the reduction electrodes being formed in predetermined intervals along the micro/nano fluidic channel and being substantially perpendicular to the micro/nano fluidic channel, wherein the reduction electrodes are electrically inter-connected.

2. A three-dimensional electrode system according to claim 1, wherein the oxidation and reduction electrodes are arranged on both sides of the micro/nano fluidic channel respectively such that they are encountered alternately along the micro/nano fluidic channel in zigzags.

3. A three-dimensional electrode system according to claim 1, wherein the oxidation and reduction electrodes have a predetermined thickness, so that prominent and depressed portions are formed on the surfaces of the first and second dielectric substrates.

4. A three-dimensional electrode system according to claim 1, wherein fluid flowing through the micro/nano fluidic channel encounters in zigzags the oxidation and reduction electrodes, in which time oxidation and reduction reactions of the fluid are alternately repeated.

5. A three-dimensional electrode system according to claim 1, wherein fluid flowing through the micro/nano fluidic channel contains electroactive species.

6. A three-dimensional electrode system according to claim 1, wherein the oxidation and reduction electrodes are spaced apart with a gap of nano-scale in- between.

7. A three-dimensional electrode system in which a micro/nano fluidic channel is integrated, the three- dimensional electrode system comprising: a) a first conductive substrate; b) a second conductive substrate facing the first conductive substrate with a gap of nano-scale in-between wherein a micro/nano fluidic channel is formed between the first and second conductive substrate; c) a plurality of first dielectric members formed on the first conductive substrate, the first dielectric members being formed in predetermined intervals along the micro/nano fluidic channel and being substantially perpendicular to the micro/nano fluidic channel; and d) a plurality of second dielectric members formed on the second conductive substrate, the second dielectric members being formed in predetermined intervals along the micro/nano fluidic channel and being substantially perpendicular to the micro/nano fluidic channel.

8. A three-dimensional electrode system according to claim 7, wherein the first and second dielectric members are arranged both sides of the micro/nano fluidic channel respectively such that they are encountered alternately along the micro/nano fluidic channel in zigzags .

9. A three-dimensional electrode system according to claim 7, wherein the first and second dielectric members have a predetermined thickness, so that prominent and depressed portions are formed on the surfaces of the first and second conductive substrates.

10. A three-dimensional electrode system according to claim 7, wherein fluid flowing through the micro/nano fluidic channel encounters in zigzags the oxidation and reduction electrodes, in which time oxidation and reduction reactions of the fluid are alternately repeated.

11. A three-dimensional electrode system according to claim 7, wherein fluid flowing through the micro/nano fluidic channel contains electroactive species.