JP2010096724A - Micro-reference electrode device - Google Patents
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Abstract
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本発明は、多くの電気化学実験、あるいは電気化学的原理に基づく化学センサ、バイオセンサにおいて用いられる微小参照電極、特に参照電極として安定で汎用性のある微小参照電極デバイスに関する。 The present invention relates to a micro reference electrode used in many electrochemical experiments or chemical sensors and biosensors based on electrochemical principles, and more particularly to a micro reference electrode device that is stable and versatile as a reference electrode.
参照電極は、電位設定あるいは電位測定の基準となる電極であり、電気化学の基礎研究のみならず、化学センサのような応用研究においてもなくてはならない重要な構成要素である。例えば、サイクリックボルタモグラム等、電極電位が情報として含まれる実験を実施するにあたっては、安定な電位基準となる参照電極が求められることは言うまでもない。 The reference electrode is an electrode that serves as a reference for potential setting or potential measurement, and is an important component that is essential not only for basic research of electrochemistry but also for applied research such as chemical sensors. For example, in conducting an experiment in which an electrode potential is included as information, such as a cyclic voltammogram, it goes without saying that a reference electrode serving as a stable potential reference is required.
また、化学センサ、バイオセンサのうち、特に電位測定を行うポテンショメトリックセンサにおいては、化学物質を測定する指示電極の電位がこの参照電極を基準に測られ、この電位を指標として化学物質濃度が測られるため、安定で信頼性の高い参照電極を用いなければ、その電位のずれがそのまま測定誤差となってしまう。このように、参照電極は、電気化学的センサにおいては基本的なものであり、かつ非常に重要なものである。 In addition, among chemical sensors and biosensors, particularly potentiometric sensors that measure potential, the potential of the indicator electrode that measures the chemical substance is measured with reference to this reference electrode, and the chemical substance concentration is measured using this potential as an index. Therefore, unless a stable and highly reliable reference electrode is used, the potential deviation becomes a measurement error as it is. Thus, the reference electrode is fundamental in electrochemical sensors and is very important.
近年、半導体加工技術による化学センサ、バイオセンサの微小化が進むにつれ、それに応じて、安定な電位を与えることのできる微小な参照電極の開発が求められるようになった（例えば、特許文献１参照）。 In recent years, with the progress of miniaturization of chemical sensors and biosensors by semiconductor processing technology, the development of minute reference electrodes capable of providing a stable potential has been demanded accordingly (for example, see Patent Document 1). ).
特許文献１に記載の参照電極によれば、全体が保護膜で覆われていると共に、少なくとも、薄膜骨組金属パターンにおけるその一部が電極端子部として露出されており、並びに、薄膜液絡パターンにおけるその一部が外部の液体との接触部として露出することにより、安定性を有する微小参照電極を得ることを可能としている。
上述したように、参照電極を微小化するアプローチとして、液絡を有する銀/塩化銀電極を微小化するのが最も現実的なアプローチであった。しかしながら、参照電極の微小化が進むにつれて、Cl-イオンの流出による内部電解液の希釈及びこれに伴う電位変動の問題は避けられなかった。 As described above, the most realistic approach for miniaturizing the reference electrode is to miniaturize a silver / silver chloride electrode having a liquid junction. However, as the reference electrode is miniaturized, the problem of dilution of the internal electrolyte due to the outflow of Cl 2 − ions and the accompanying potential fluctuation cannot be avoided.
また、微小化学分析システム（μTAS）の中でも、電気化学測定に基づくものは微小化や大量生産などにおいて有利であり、実用的なデバイス開発に期待が高まっており、このうちポテンショメトリック等、電位を問題にする場合には、電位基準となる参照電極が非常に重要な役割を果たす。ここで、参照極としてμTASでも用いられる銀／塩化銀電極は、電位を一定に維持するために、電極付近のCl−濃度を一定に維持する必要がある。しかしながら、μTASのような微小空間内でこれは極めて困難である。 Among microchemical analysis systems (μTAS), those based on electrochemical measurements are advantageous for miniaturization and mass production, and there are increasing expectations for practical device development. In the case of a problem, the reference electrode serving as a potential reference plays a very important role. Here, the silver / silver chloride electrode used in the μTAS as the reference electrode needs to keep the Cl − concentration in the vicinity of the electrode constant in order to keep the potential constant. However, this is extremely difficult in a micro space such as μTAS.
本発明は以上のような課題に鑑みてなされたものであり、その目的は、参照極付近のイオン濃度を一定に維持することを可能とした微小参照電極デバイスを提供することにある。 The present invention has been made in view of the problems as described above, and an object thereof is to provide a micro reference electrode device capable of maintaining a constant ion concentration in the vicinity of a reference electrode.
本発明の微小参照電極デバイスは、作用極が配置され、所定の電解液を収容する作用極区画と、参照極及び対極が配置され、所定の電解液を収容し、第１の液絡路を介して作用極区画内の電解液と電解液の接触が図られるともに、第２の液絡路を介して計測対象となる液体と電解液の接触が図られた参照極区画とを備え、作用極と参照極との電位差を固定し、参照極区画内の電解液における所定のイオン濃度が変化した場合に作用極に生じる電流と逆符号の電流を対極に流し、参照極区画内の所定のイオン濃度を一定とすることを特徴とする。 The micro reference electrode device according to the present invention includes a working electrode section in which a working electrode is disposed and a predetermined electrolytic solution is accommodated, a reference electrode and a counter electrode are disposed, the predetermined electrolytic solution is accommodated, and the first liquid junction is provided. And a reference electrode section in which contact is made between the liquid to be measured and the electrolyte solution through the second liquid junction, The potential difference between the reference electrode and the reference electrode is fixed, and when a predetermined ion concentration in the electrolyte solution in the reference electrode section changes, a current having a sign opposite to that generated in the working electrode is supplied to the counter electrode, The ion concentration is constant.
また、本発明の微小参照電極デバイスの制御方法は、作用極が配置され、所定の電解液を収容する作用極区画と、参照極及び対極が配置され、所定の電解液を収容し、第１の液絡路を介して作用極区画内の電解液と電解液の接触が図られるともに、第２の液絡路を介して計測対象となる液体と電解液の接触が図られた参照極区画とを備える微小参照電極デバイスの制御方法であって、作用極と参照極との電位差を固定し、参照極区画内の電解液における所定のイオン濃度が変化した場合に作用極に生じる電流と逆符号の電流を対極に流し、参照極区画内の所定のイオン濃度を一定とすることを特徴とする。 The method for controlling a micro reference electrode device of the present invention includes a working electrode section in which a working electrode is disposed and a predetermined electrolytic solution is accommodated, a reference electrode and a counter electrode are disposed, a predetermined electrolytic solution is accommodated, and the first The reference electrode compartment in which contact between the electrolytic solution and the electrolytic solution in the working electrode compartment is achieved through the liquid junction, and the liquid to be measured and the electrolytic solution are contacted through the second liquid junction The method of controlling a micro reference electrode device comprising: a fixed potential difference between a working electrode and a reference electrode; and a reverse of the current generated in the working electrode when a predetermined ion concentration in the electrolyte solution in the reference electrode section changes A current of a sign is made to flow to the counter electrode, and a predetermined ion concentration in the reference electrode section is made constant.
以上のような本発明の微小参照電極デバイスによれば、参照極外部のイオン濃度が変動した場合にも、フィードバック機能により、参照極付近のイオン濃度を一定に維持し、安定的な電位を示す微小参照電極デバイスを実現することが可能となる。 According to the micro reference electrode device of the present invention as described above, even when the ion concentration outside the reference electrode fluctuates, the ion concentration in the vicinity of the reference electrode is maintained constant by the feedback function and shows a stable potential. A minute reference electrode device can be realized.
図１は、本実施形態の微小参照電極デバイスの全体構成を示す図である。図１（ａ）は、本実施形態の微小参照電極デバイスの正面図であり、図１（ｂ）は、本実施形態の微小参照電極デバイスの側面図である。 FIG. 1 is a diagram showing the overall configuration of the micro reference electrode device of the present embodiment. FIG. 1A is a front view of the micro reference electrode device of the present embodiment, and FIG. 1B is a side view of the micro reference electrode device of the present embodiment.
図に示すように、本実施形態の微小参照電極デバイス１はＰＤＭＳ（Poly Dimethyl Siloxane）基板１００と、絶縁層２００と、ガラス基板３００が積層して構成される。本実施形態の微小参照電極デバイス１の概略の外形サイズは、20mm×15mmである。 As shown in the figure, the micro reference electrode device 1 of the present embodiment is configured by laminating a PDMS (Poly Dimethyl Siloxane) substrate 100, an insulating layer 200, and a glass substrate 300. The outline external size of the micro reference electrode device 1 of the present embodiment is 20 mm × 15 mm.
図２は、本実施形態の微小参照電極デバイスの分解斜視図である。また、図３は、本実施形態の微小参照電極デバイス１における図１中のＡ部を拡大した図である。 FIG. 2 is an exploded perspective view of the micro reference electrode device of the present embodiment. Moreover, FIG. 3 is the figure which expanded the A section in FIG. 1 in the micro reference electrode device 1 of this embodiment.
本実施形態のＰＤＭＳ基板１００は、注入口１０１と、作用極区画１０２と、参照極区画１０３と、参照極用溶液注入ポート１０４と、第１のサンプル注入ポート１０５と、第２のサンプル注入ポート１０６と、第１の微小流路１０７と、第２の微小流路１０８とを含んで構成される。 The PDMS substrate 100 of this embodiment includes an injection port 101, a working electrode section 102, a reference electrode section 103, a reference electrode solution injection port 104, a first sample injection port 105, and a second sample injection port. 106, a first microchannel 107, and a second microchannel 108.
注入口１０１は、ＰＤＭＳ基板１００を貫通する円形断面の穴である。注入口１０１は、後述するデバイス内の参照極３１０の電位を計測するための市販の銀／塩化銀参照極を挿入するための区画である。注入口１０１の直径は、6ｍｍである。 The injection port 101 is a hole having a circular cross section that penetrates the PDMS substrate 100. The inlet 101 is a compartment for inserting a commercially available silver / silver chloride reference electrode for measuring the potential of a reference electrode 310 in the device described later. The diameter of the inlet 101 is 6 mm.
作用極区画１０２は、ＰＤＭＳ基板１００を貫通し、突起部１０２ａを有するほぼ円形断面の穴である。作用極区画１０２は、図５に示すように、突起部１０２ａ及び第１の液絡路１１０を介して参照極区画１０３に接続している。作用極区画１０２の直径は、3ｍｍである。 The working electrode section 102 is a hole having a substantially circular cross section that penetrates the PDMS substrate 100 and has a protrusion 102a. As shown in FIG. 5, the working electrode section 102 is connected to the reference electrode section 103 via the protrusion 102 a and the first liquid junction 110. The working electrode section 102 has a diameter of 3 mm.
また、作用極区画１０２には電解質ゲル４００がほぼ密に配置され収容される。電解質ゲル４００は、後述する参照極区画１０３内の電解液と接触する。本実施形態では、作用極３０４が配置される作用極区画１０２内は塩化物イオンの濃度が一定であることが前提となるが、これは同時に作用極３０４の電位が常に一定であることを意味するものである。そのため、本実施形態では、作用極区画１０２内を塩化物イオンを一定に含むゲルで満たすことにより、作用極３０４の電位を常に一定としている。 In addition, the electrolyte gel 400 is disposed in the working electrode section 102 in a substantially dense manner. The electrolyte gel 400 is in contact with an electrolyte solution in a reference electrode section 103 described later. In the present embodiment, it is assumed that the concentration of chloride ions is constant in the working electrode section 102 in which the working electrode 304 is disposed. This means that the potential of the working electrode 304 is always constant at the same time. To do. Therefore, in this embodiment, the potential of the working electrode 304 is always constant by filling the working electrode section 102 with a gel containing chloride ions.
参照極区画１０３は、ＰＤＭＳ基板１００を貫通する円形断面の穴である。参照極区画１０３は、塩化物イオン濃度のフィードバックの基準となる所定の濃度のKCl溶液を収容する。参照極区画１０３は、図５に示すように第２の液絡路１０９を介して、第１の微小流路１０７に接続している。参照極区画１０３の直径は800μｍである。また、第２の液絡路１０９の幅は、200μｍである。 The reference electrode section 103 is a hole having a circular cross section that penetrates the PDMS substrate 100. The reference electrode section 103 accommodates a KCl solution having a predetermined concentration serving as a reference for feedback of chloride ion concentration. The reference electrode section 103 is connected to the first microchannel 107 via the second liquid junction 109 as shown in FIG. The diameter of the reference electrode section 103 is 800 μm. The width of the second liquid junction 109 is 200 μm.
参照極用溶液注入ポート１０４は、ＰＤＭＳ基板１００を貫通する円形断面の穴である。参照極用溶液注入ポート１０４は、参照極３１０のためのKCl溶液を参照極区画１０３へ供給するためのポートである。参照極用溶液注入ポート１０４は、第２の微小流路１０８を介して、参照極区画１０３に接続している。参照極用溶液注入ポート１０４の直径は、500μｍである。また、第２の微小流路１０８の幅は約100μｍである。 The reference electrode solution injection port 104 is a hole having a circular cross section that penetrates the PDMS substrate 100. The reference electrode solution injection port 104 is a port for supplying a KCl solution for the reference electrode 310 to the reference electrode section 103. The reference electrode solution injection port 104 is connected to the reference electrode section 103 via the second microchannel 108. The diameter of the reference electrode solution injection port 104 is 500 μm. The width of the second microchannel 108 is about 100 μm.
参照極区画１０３へKCl溶液を注入する目的は、参照極区画１０３内の塩化物イオン濃度をフィードバックの基準となる濃度にするためである。最初に、参照極区画１０３内を、基準となる塩化物イオン濃度で満たすことで、続いてどのような塩化物イオン濃度のサンプルが流れてきても、フィードバックによって最初の基準の濃度が参照極区間１０３内では維持されることとなる。 The purpose of injecting the KCl solution into the reference electrode compartment 103 is to make the chloride ion concentration in the reference electrode compartment 103 a concentration that serves as a reference for feedback. First, the reference electrode section 103 is filled with the reference chloride ion concentration, so that whatever the concentration of the chloride ion subsequently flows, the first reference concentration becomes the reference electrode interval by feedback. It will be maintained in 103.
第１のサンプル注入ポート１０５及び第２のサンプル注入ポート１０６は、ＰＤＭＳ基板１００を貫通する円形断面の穴である。第１のサンプル注入ポート１０５及び第２のサンプル注入ポート１０６は、第１の微小流路１０７へ計測対象となるサンプル液を供給するためのポートである。第１のサンプル注入ポート１０５及び第２のサンプル注入ポート１０６は、第１の微小流路１０７を介して、注入口１０１に接続している。第１のサンプル注入ポート１０５及び第２のサンプル注入ポート１０６の直径は、800μｍである。また、第１の微小流路１０７の幅は約500μｍである。 The first sample injection port 105 and the second sample injection port 106 are holes having a circular cross section that penetrates the PDMS substrate 100. The first sample injection port 105 and the second sample injection port 106 are ports for supplying a sample liquid to be measured to the first microchannel 107. The first sample injection port 105 and the second sample injection port 106 are connected to the injection port 101 via the first microchannel 107. The diameters of the first sample injection port 105 and the second sample injection port 106 are 800 μm. Further, the width of the first microchannel 107 is about 500 μm.
本実施形態の絶縁層２００はポリイミドからなり、作用極導通部２０１と、対極・参照極導通部２０２とを有する。 The insulating layer 200 of the present embodiment is made of polyimide, and has a working electrode conductive portion 201 and a counter electrode / reference electrode conductive portion 202.
作用極導通部２０１は、絶縁層２００を貫通する孔が配置されることにより構成される。作用極導通部２０１は、作用極区画１０２の断面及び後述する作用極３０４とほぼ同一の面積の孔である。作用極導通部２０１を作用極３０４とほぼ同一の面積の孔とすることにより、作用極３０４に流れる電流を出来るだけ大きくしている。本実施形態では、作用極導通部２０１の直径を3ｍｍとする。 The working electrode conductive portion 201 is configured by arranging a hole penetrating the insulating layer 200. The working electrode conducting portion 201 is a hole having substantially the same area as a cross section of the working electrode section 102 and a working electrode 304 described later. By making the working electrode conducting portion 201 a hole having substantially the same area as that of the working electrode 304, the current flowing through the working electrode 304 is made as large as possible. In the present embodiment, the working electrode conductive portion 201 has a diameter of 3 mm.
図４は、本実施形態の対極・参照極導通部２０２の拡大図である。対極・参照極導通部２０２は、絶縁層２００を貫通するほぼ円形の対極導通部２０３と、対極導通部２０３の内部の中心に突出し円形先端を有する参照極被覆部２０４と、参照極被覆部２０４を貫通し対極導通部２０３のほぼ中心に位置する微小な穴である参照極導通部２０５とを有する。参照極被覆部２０４の円形先端は直径300μｍであり、対極導通部２０３の直径は、750μｍである。 FIG. 4 is an enlarged view of the counter electrode / reference electrode conducting portion 202 of the present embodiment. The counter electrode / reference electrode conducting portion 202 includes a substantially circular counter electrode conducting portion 203 that penetrates the insulating layer 200, a reference electrode covering portion 204 that protrudes from the center of the counter electrode conducting portion 203 and has a circular tip, and a reference electrode covering portion 204. And a reference electrode conducting portion 205 that is a minute hole that is positioned substantially at the center of the counter electrode conducting portion 203. The circular tip of the reference electrode covering portion 204 has a diameter of 300 μm, and the counter electrode conducting portion 203 has a diameter of 750 μm.
また、本実施形態では、参照極導通部２０５の直径を50μｍとしている。これは、一般に、塩化銀は高濃度の塩化物イオンを含む溶液中では錯体を形成し溶解してしまうことが知られており、微小な銀／塩化銀参照極ではこのことが原因で電位が安定せず耐久性もあまり良くはない。本実施形態のように参照極導通部２０５をピンホールとし、露出する面積を極端に制限することで、塩化銀の溶解が劇的に抑えられ、参照極３１０の安定性と耐久性を向上することを可能としている。 In the present embodiment, the diameter of the reference electrode conducting portion 205 is 50 μm. In general, it is known that silver chloride forms a complex and dissolves in a solution containing a high concentration of chloride ions, and the potential of a fine silver / silver chloride reference electrode is caused by this. Not stable and not very durable. As in this embodiment, the reference electrode conducting portion 205 is a pinhole, and the exposed area is extremely limited, so that the dissolution of silver chloride is dramatically suppressed, and the stability and durability of the reference electrode 310 are improved. Making it possible.
本実施形態のガラス基板３００は、対極用パッド３０１、作用極用パッド３０２、参照極用パッド３０３、作用極３０４、対極・参照極部３０５、及び配線パターン３０６、３０７、３０８が、その表面に形成されて構成される。 The glass substrate 300 of the present embodiment has a counter electrode pad 301, a working electrode pad 302, a reference electrode pad 303, a working electrode 304, a counter electrode / reference electrode portion 305, and wiring patterns 306, 307, and 308 on the surface. Formed and configured.
図２に示すように、矩形のガラス基板３００の一辺に、対極用パッド３０１、作用極用パッド３０２、及び参照極用パッド３０３が順に並んで配置されている。 As shown in FIG. 2, a counter electrode pad 301, a working electrode pad 302, and a reference electrode pad 303 are sequentially arranged on one side of a rectangular glass substrate 300.
ガラス基板３００のほぼ中心部には、円形の作用極３０４が形成されている。作用極３０４は、銀／塩化銀の非分極性の電極である。作用極３０４と作用極用パッド３０２とは、配線パターン３０７により電気的に接続している。作用極３０４の直径は3ｍｍである。 A circular working electrode 304 is formed substantially at the center of the glass substrate 300. The working electrode 304 is a nonpolarizable electrode of silver / silver chloride. The working electrode 304 and the working electrode pad 302 are electrically connected by a wiring pattern 307. The working electrode 304 has a diameter of 3 mm.
ガラス基板３００上の作用極３０４付近には対極・参照極部３０５が形成されている。図５は、本実施形態の対極・参照極部３０５の拡大図である。図に示すように、対極・参照極部３０５は、円形の参照極３１０と、参照極３１０を所定の間隔をもって包囲したほぼ中空円状の対極３０９を有する。対極３０９及び参照極３１０は、銀／塩化銀の非分極性の電極である。参照極３１０は、参照極区画１０３内の塩化物イオン濃度変化を計測するため、参照極区画１０３の端などよりも中心に配置している。そして、残りの面積を対極３０９で占めようとする結果、対極３０９を参照極３１０を包囲するような形状としている。参照極３１０の直径は、200μｍであり、対極３０９の外形は750μｍである。 Near the working electrode 304 on the glass substrate 300, a counter electrode / reference electrode portion 305 is formed. FIG. 5 is an enlarged view of the counter electrode / reference electrode unit 305 of the present embodiment. As shown in the figure, the counter electrode / reference electrode unit 305 includes a circular reference electrode 310 and a substantially hollow circular counter electrode 309 that surrounds the reference electrode 310 at a predetermined interval. The counter electrode 309 and the reference electrode 310 are silver / silver chloride non-polarizable electrodes. The reference electrode 310 is arranged at the center rather than the end of the reference electrode section 103 in order to measure a change in the chloride ion concentration in the reference electrode section 103. Then, as a result of trying to occupy the remaining area with the counter electrode 309, the counter electrode 309 is shaped to surround the reference electrode 310. The diameter of the reference electrode 310 is 200 μm, and the outer shape of the counter electrode 309 is 750 μm.
参照極３１０は、配線パターン３０８を介して参照極用パッド３０３と電気的に接続している。対極３０９は、配線パターン３０６を介して対極用パッド３０１と電気的に接続している。 The reference electrode 310 is electrically connected to the reference electrode pad 303 via the wiring pattern 308. The counter electrode 309 is electrically connected to the counter electrode pad 301 via the wiring pattern 306.
上述した、ＰＤＭＳ基板１００と、絶縁層２００と、ガラス基板３００が積層して構成されることにより、本実施形態の微小参照電極デバイスは以下の構成を有することとなる。 When the PDMS substrate 100, the insulating layer 200, and the glass substrate 300 described above are stacked, the micro reference electrode device of the present embodiment has the following configuration.
ＰＤＭＳ基板１００の注入口１０１と、参照極用溶液注入ポート１０４と、第１のサンプル注入ポート１０５と、第２のサンプル注入ポート１０６と、第１の微小流路１０７と、第２の微小流路１０８とについては、下部に絶縁層２００が存在し、内部の電解液は各ポート及び流路に保持される。 PDMS substrate 100 inlet 101, reference electrode solution injection port 104, first sample injection port 105, second sample injection port 106, first microchannel 107, and second microflow With respect to the channel 108, the insulating layer 200 exists in the lower part, and the internal electrolyte is held in each port and channel.
一方、ＰＤＭＳ基板１００の作用極区画１０２の下部には、絶縁層２００の作用極導通部２０１が配置され、さらに下部には、ガラス基板３００の参照極３０４が配置される。これにより、作用極区画１０２内の電解質ゲル４００と参照極３０４とは電解液の接触が図られることとなる。 On the other hand, the working electrode conductive portion 201 of the insulating layer 200 is disposed below the working electrode section 102 of the PDMS substrate 100, and the reference electrode 304 of the glass substrate 300 is disposed further below. As a result, the electrolyte gel 400 and the reference electrode 304 in the working electrode section 102 are brought into contact with the electrolytic solution.
また、ＰＤＭＳ基板１００の参照極区画１０３の下部には、絶縁層２００の対極・参照極導通部２０２が配置され、さらに下部には、ガラス基板３００の対極・参照極部３０５が配置される。 In addition, the counter electrode / reference electrode conducting portion 202 of the insulating layer 200 is disposed below the reference electrode section 103 of the PDMS substrate 100, and the counter electrode / reference electrode portion 305 of the glass substrate 300 is disposed further below.
ここで、絶縁層２００の対極・参照極導通部２０２の絶縁膜の形状は上述したように、対極導通部２０３を介して対極３０９が露出し、微小な穴である参照極導通部２０５を介して参照極３１０の一部が露出する形状であるため、参照極区画１０３内の電解液と対極３０９及び参照極３１０との接触が図られることとなる。 Here, as described above, the shape of the insulating film of the counter electrode / reference electrode conducting portion 202 of the insulating layer 200 is such that the counter electrode 309 is exposed through the counter electrode conducting portion 203 and the reference electrode conducting portion 205 which is a minute hole. Thus, since the reference electrode 310 is partially exposed, the electrolyte solution in the reference electrode section 103 is brought into contact with the counter electrode 309 and the reference electrode 310.
参照極用溶液注入ポート１０４から参照極区画１０３へKCl溶液が供給される。第１のサンプル注入ポート１０５及び第２のサンプル注入ポート１０６からは、第１の微小流路１０７を介して、注入口１０１へのサンプル液の流れが生じるが、第１の微小流路１０７内のサンプル液の一部は、第２の液絡路１０９を介して参照極区画１０３内の電解液と接触する。 A KCl solution is supplied from the reference electrode solution injection port 104 to the reference electrode section 103. From the first sample injection port 105 and the second sample injection port 106, a sample liquid flows to the injection port 101 via the first microchannel 107. A part of the sample solution comes into contact with the electrolytic solution in the reference electrode section 103 via the second liquid junction 109.
また、作用極区画１０２の電解質ゲル４００と参照極区画１０３内の電解液とは、第１の液絡路１１０を介して接触する。 In addition, the electrolyte gel 400 in the working electrode section 102 and the electrolyte solution in the reference electrode section 103 are in contact via the first liquid junction 110.
次に、本実施形態の微小参照電極デバイスの１チップ分の作製方法を説明するが、実際には１枚の基板上に多数の微小参照電極デバイスが一括して作製されるものである。 Next, a manufacturing method for one chip of the micro reference electrode device of the present embodiment will be described. Actually, however, a large number of micro reference electrode devices are manufactured collectively on a single substrate.
［製造例１］
（１）ガラス基板洗浄
7740ガラス基板（３インチ、500μm厚）を加熱した31%過酸化水素：29%アンモニア：純水＝１：１：４溶液中、および加熱した純水中で洗浄した。
[Production Example 1]
(1) Glass substrate cleaning
A 7740 glass substrate (3 inches, 500 μm thick) was washed in a heated 31% hydrogen peroxide: 29% ammonia: pure water = 1: 1: 4 solution and in heated pure water.
（２）ガラス基板３００上の骨格パターンの形成
（１）のガラス基板上に銀／塩化銀構造の骨組みとなる金パターンを形成した。金パターンは、電極パッド３０１〜３０３及び配線パターン３０６〜３０８を構成するものである。また、金パターンは、骨格パターン状に作用極３０４、対極３０９、及び参照極３１０の第１層を構成するものである。
(2) Formation of skeleton pattern on glass substrate 300 A gold pattern that forms a framework of a silver / silver chloride structure was formed on the glass substrate of (1). The gold pattern constitutes the electrode pads 301 to 303 and the wiring patterns 306 to 308. The gold pattern constitutes the first layer of the working electrode 304, the counter electrode 309, and the reference electrode 310 in a skeleton pattern.
まず、スパッタにより40 nm厚のクロム層、300 nm厚の金層を、順に基板全面に形成した。次に、ポジ型フォトレジスト（Shipley製、S1818）によりパターニングを施し、以下に示すエッチング液中で金のエッチングを行った。 First, a chromium layer having a thickness of 40 nm and a gold layer having a thickness of 300 nm were sequentially formed on the entire surface of the substrate by sputtering. Next, patterning was performed using a positive photoresist (S1818, manufactured by Shipley), and gold was etched in the following etching solution.
金のエッチング液： ヨウ化カリウム10 gとヨウ素2.5 gを純水100 mlに溶かしたもの。 Gold etching solution: 10 g of potassium iodide and 2.5 g of iodine dissolved in 100 ml of pure water.
エッチング後アセトン中でレジストを剥離し、同じくアセトン中で十分に洗浄・乾燥した。引き続き、基板を以下のエッチング液中の浸漬し、クロム層を除去した。 After etching, the resist was peeled off in acetone, and also thoroughly washed and dried in acetone. Subsequently, the substrate was immersed in the following etching solution to remove the chromium layer.
クロムエッチング液： フェリシアン化カリウム 25 gと水酸化ナトリウム 12.5 g を100 mlの純水に溶かしたもの Chromium etchant: 25 g potassium ferricyanide and 12.5 g sodium hydroxide dissolved in 100 ml pure water
エッチング後、基板を純水で十分に洗浄し、乾燥窒素ガスにより乾燥した。これにより、骨格となるパターンが完成した。ここで用いられる金属材料は必ずしも金に限らない。それ自身電極反応でおかされにくい、白金等、他の貴金属を用いることも可能である。 After etching, the substrate was thoroughly washed with pure water and dried with dry nitrogen gas. Thereby, the pattern used as a skeleton was completed. The metal material used here is not necessarily gold. It is also possible to use other noble metals such as platinum which are not easily affected by the electrode reaction.
（３）銀用リフトオフパターンの形成
（２）の金の骨組みが完成した基板上に、ポジ型フォトレジスト（Shipley製、S1818）によるリフトオフ用パターンを形成した。まず、ポジ型フォトレジストを基板上にスピンコーティングした後、80℃で30分ベーキングを施した。次に必要なパターンを形成したフォトマスクを使用し、露光した後、30 ℃のトルエン中に1分間浸漬し、乾燥後、80℃で15分ベーキングを施した。その後、ポジ型フォトレジスト用現像液（Shipley製、MF319）中で現像、純水でリンスを行い、乾燥窒素ガスを吹き付け乾燥した。
(3) Formation of lift-off pattern for silver A lift-off pattern was formed on the substrate on which the gold framework of (2) was completed by using a positive photoresist (S1818, manufactured by Shipley). First, a positive photoresist was spin-coated on a substrate and then baked at 80 ° C. for 30 minutes. Next, using a photomask on which a necessary pattern was formed, the film was exposed, immersed in toluene at 30 ° C. for 1 minute, dried, and baked at 80 ° C. for 15 minutes. After that, development was performed in a positive photoresist developer (manufactured by Shipley, MF319), rinsed with pure water, and dried by blowing dry nitrogen gas.
（４）銀薄膜の形成
銀を300 nmの厚さにスパッタした。
(4) Formation of silver thin film Silver was sputtered to a thickness of 300 nm.
（５）リフトオフ
（４）の銀薄膜をスパッタした基板をアセトン中に浸漬してレジストを溶解し、レジストパターン上の銀薄膜をリフトオフした。その後、清浄なアセトンにて十分に洗浄後、乾乾燥窒素ガスを吹き付け乾燥した。このようにして、作用極３０４、対極３０９、及び参照極３１０を構成する骨格金パターン上に、第２層として銀薄膜が形成される。
(5) Lift-off The substrate on which the silver thin film of (4) was sputtered was immersed in acetone to dissolve the resist, and the silver thin film on the resist pattern was lifted off. Then, after thoroughly washing with clean acetone, dry-drying nitrogen gas was blown and dried. In this manner, a silver thin film is formed as the second layer on the skeleton gold pattern constituting the working electrode 304, the counter electrode 309, and the reference electrode 310.
（６）絶縁膜２００内のパターンの形成
（５）の電極群を形成したガラス基板３００上に絶縁膜２００ポリイミドのパターンを形成した。まず、ポリイミドプレポリマー（東レ製、SP-341）を基板上にスピンコーティングした後、80℃で30分ベーキングを施した。次に、ポジ型フォトレジスト（Shipley製、S1818）をスピンコーティングした後、80℃で30分ベーキングを施した。その後、必要なパターンを形成したフォトマスクを使用し、露光した後、ポジ型フォトレジスト用現像液（Shipley製、MF319）中で現像、純水でリンスを行い、乾燥窒素ガスを吹き付け乾燥した。最後に、エタノールでレジストを十分剥離し、乾燥窒素ガスを吹き付け乾燥した後、150℃で15分、200℃で15分、300℃で30分キュアした。電極感応部が上記によって絶縁されたが、電極の露出部分のサイズは、作用極導通部２０１が直径3 mm、参照極導通部２０５が直径50 μm、及び対極導通部２０３が外形750 μmと内径300 μmの同心円内とした。
(6) Formation of pattern in insulating film 200 A pattern of the insulating film 200 polyimide was formed on the glass substrate 300 on which the electrode group of (5) was formed. First, a polyimide prepolymer (Toray, SP-341) was spin-coated on a substrate, and then baked at 80 ° C. for 30 minutes. Next, a positive photoresist (S1818, manufactured by Shipley) was spin-coated and then baked at 80 ° C. for 30 minutes. Thereafter, using a photomask having a necessary pattern formed, exposure was performed, followed by development in a positive photoresist developer (manufactured by Shipley, MF319), rinsing with pure water, and drying by blowing dry nitrogen gas. Finally, the resist was sufficiently peeled off with ethanol, dried by blowing dry nitrogen gas, and then cured at 150 ° C. for 15 minutes, 200 ° C. for 15 minutes, and 300 ° C. for 30 minutes. Although the electrode sensitive part was insulated by the above, the exposed electrode size was 3 mm in diameter for the working electrode conducting part 201, 50 μm in the reference electrode conducting part 205, and 750 μm in the outer diameter of the counter electrode conducting part 203 in the outer diameter. It was within a 300 μm concentric circle.
（７）基板のダイシング
ダイシングソーにてウエハから微小参照電極のチップを切り出した。
(7) Dicing of substrate A chip of a minute reference electrode was cut out from a wafer with a dicing saw.
（８）塩化銀層の形成
チップ上の全ての銀電極上に塩化銀層を形成した。まず、銀電極を白金板、市販の銀／塩化銀電極とともに0.1 M KClを含むKCl - HCl緩衝液 (pH 2.2, 25℃)中に浸漬した。次に、銀電極を作用極、白金板を対極、市販の銀／塩化銀電極を参照極としてガルバノスタットに接続し、一定電流を数分間流し、定常電解にて塩化銀層を形成した。印加電流値と印加時間は電極役割に応じて異なり、作用極は0.1 μAで15分、参照極は10 nAで15分、対極は1 μAで20 分とした。形成後、純水にて洗浄し、乾燥した。このようにして、作用極３０４、対極３０９、及び参照極３１０を構成する銀薄膜上に、第３層として塩化銀層が形成される。
(8) Formation of silver chloride layer A silver chloride layer was formed on all the silver electrodes on the chip. First, the silver electrode was immersed in a KCl-HCl buffer solution (pH 2.2, 25 ° C.) containing 0.1 M KCl together with a platinum plate and a commercially available silver / silver chloride electrode. Next, the silver electrode was connected to a galvanostat using a working electrode, a platinum plate as a counter electrode, and a commercially available silver / silver chloride electrode as a reference electrode, a constant current was passed for several minutes, and a silver chloride layer was formed by steady electrolysis. The applied current value and the application time differed depending on the role of the electrode. The working electrode was 0.1 μA for 15 minutes, the reference electrode was 10 nA for 15 minutes, and the counter electrode was 1 μA for 20 minutes. After formation, it was washed with pure water and dried. In this manner, a silver chloride layer is formed as the third layer on the silver thin film constituting the working electrode 304, the counter electrode 309, and the reference electrode 310.
（９）微小流路鋳型の形成
（１）のガラス基板３００上に微小流路構造を形成するための鋳型を形成した。まず、基板上に厚膜フォトレジスト（Microchem製、SU-8 25）をスピンコーティングした後、65℃で5分、95℃で25分ベーキングを施した。次に、必要なパターンを形成したフォトマスクを使用し、露光した後、65℃で10分ベーキングを施した。その語、厚膜フォトレジスト用現像液（Microchem製、SU-8 Developer）中で現像、純水でリンスを行い、乾燥窒素ガスを吹き付け乾燥した。
(9) Formation of Microchannel Template A template for forming a microchannel structure was formed on the glass substrate 300 of (1). First, a thick film photoresist (manufactured by Microchem, SU-8 25) was spin-coated on the substrate, and then baked at 65 ° C. for 5 minutes and at 95 ° C. for 25 minutes. Next, using a photomask on which a necessary pattern was formed, exposure was performed, and baking was performed at 65 ° C. for 10 minutes. In that word, it was developed in a developer for thick film photoresist (manufactured by Microchem, SU-8 Developer), rinsed with pure water, and dried by blowing dry nitrogen gas.
（１０）PDMS基板１００の作製
（９）の鋳型を使用してPDMS（ポリジメチルキロキサン）基板１００を作製した。まず、基板上にPDMS前駆体と硬化剤を10：1の質量比で混合したものを均一に塗布した。続いて、簡易真空ポンプで気泡を除去し、室温下で一夜放置し硬化させた。その後、硬化したPDMSを鋳型から剥がして、メスで切り出した後、穴あけポンチで溶液導入孔及び排出孔となる貫通孔を形成した。微小流路構造のサイズは、第１の微小流路１０７を幅500 μm、参照極区画１０３を直径800 μm、作用極区画１０２を直径3 mmとし、高さを全て50 μmとした。
(10) Production of PDMS substrate 100 A PDMS (polydimethylkiloxane) substrate 100 was produced using the template of (9). First, a mixture of a PDMS precursor and a curing agent at a mass ratio of 10: 1 was uniformly applied on a substrate. Subsequently, the bubbles were removed with a simple vacuum pump and allowed to stand overnight at room temperature for curing. Thereafter, the cured PDMS was peeled off from the mold, cut out with a scalpel, and then a through hole to be a solution introduction hole and a discharge hole was formed with a punch. The size of the microchannel structure was such that the first microchannel 107 had a width of 500 μm, the reference electrode section 103 had a diameter of 800 μm, the working electrode section 102 had a diameter of 3 mm, and the height was all 50 μm.
（１１）デバイスの組み立て
（８）と（１０）の基板同士を慎重に張り合わせて本製造例の微小参照電極デバイス１を組み立てた。その後、マイクロシリンジポンプから溶液を導入するために、シリコーンチューブを溶液導入孔へ挿入し、一端を接着した。
(11) Device assembly The substrates of (8) and (10) were carefully bonded together to assemble the micro reference electrode device 1 of this production example. Thereafter, in order to introduce the solution from the micro syringe pump, a silicone tube was inserted into the solution introduction hole, and one end was adhered.
［製造例２］
（１）電極チップの作製
製造例１（１）〜（８）と同様にして、銀／塩化銀電極を形成した電極チップを形成した。
[Production Example 2]
(1) Production of electrode chip In the same manner as in Production Examples 1 (1) to (8), an electrode chip on which a silver / silver chloride electrode was formed was formed.
（２）PDMS基板の作製
製造例１（９）〜（１０）と同様にして、PDMS基板を作製した。ただし、製造例１とは異なり、作用極区画１０２に直径3 mmの貫通孔を形成した。
(2) Production of PDMS substrate A PDMS substrate was produced in the same manner as in Production Examples 1 (9) to (10). However, unlike Production Example 1, a through hole having a diameter of 3 mm was formed in the working electrode section 102.
（３）デバイスの組み立て
製造例１（１１）と同様にして、本製造例の微小参照電極デバイス１を組み立てた。
(3) Device assembly The micro reference electrode device 1 of this production example was assembled in the same manner as in Production Example 1 (11).
（４）電解質ゲル４００の作製
PVA-SbQと0.2 MのKClを含む20 mM KH2PO4- NaOH緩衝液（pH 7.2, 25℃）を1：1の質量比で混合した前駆体を、作用極区画に注入した。その後、紫外線を15分間照射し、前駆体をゲル化させ、電解質ゲル４００を作製した。
(4) Preparation of electrolyte gel 400
A precursor mixed with PVA-SbQ and 20 mM KH 2 PO 4 -NaOH buffer (pH 7.2, 25 ° C.) containing 0.2 M KCl at a mass ratio of 1: 1 was injected into the working electrode compartment. Thereafter, ultraviolet rays were irradiated for 15 minutes to gel the precursor, and an electrolyte gel 400 was produced.
本実施形態の微小参照電極デバイス１はポテンショスタット５００に接続されて使用される。図６は、本実施形態の微小参照電極デバイス１とポテンショスタット５００との接続方法を示す図である。 The micro reference electrode device 1 of the present embodiment is used by being connected to a potentiostat 500. FIG. 6 is a diagram illustrating a method for connecting the micro reference electrode device 1 and the potentiostat 500 according to the present embodiment.
図に示すように、本実施形態の微小参照電極デバイス１の参照極用パッド３０３はポテンショスタット５００の参照極用端子５００ａに接続し、作用極用パッド３０２は作用極用端子５００ｂに接続し、対極用パッド３０１は対極用端子５００ｃに接続している。 As shown in the drawing, the reference electrode pad 303 of the micro reference electrode device 1 of the present embodiment is connected to the reference electrode terminal 500a of the potentiostat 500, the working electrode pad 302 is connected to the working electrode terminal 500b, The counter electrode pad 301 is connected to the counter electrode terminal 500c.
ここで、作用極３０４、対極３０９及び参照極３１０を構成する銀／塩化銀電極の性質について説明する。図７は、銀／塩化銀電極の性質を説明する図である。図７（ａ）に示すように、銀／塩化銀電極は、ネルンストの式により、電極付近の塩化物イオン濃度で電位値が決定する。ここで、図７（ｂ）に示すように、ポテンショスタットなどを用いて、この電位値より正、もしくは、負に電位値を動かそうとすると（つまり、過電圧をかけようとすると）、わずかに電位がずれるだけで大電流が発生する。この性質を非分極性という。 Here, the properties of the silver / silver chloride electrode constituting the working electrode 304, the counter electrode 309, and the reference electrode 310 will be described. FIG. 7 is a diagram for explaining the properties of the silver / silver chloride electrode. As shown in FIG. 7A, the potential value of the silver / silver chloride electrode is determined by the chloride ion concentration in the vicinity of the electrode according to the Nernst equation. Here, as shown in FIG. 7B, if a potential value is moved more positively or negatively than this potential value using a potentiostat or the like (that is, an overvoltage is applied), A large current is generated only by a potential shift. This property is called non-polarizability.
本実施形態の微小参照電極デバイスは、このような銀／塩化銀電極の性質を利用するものである。 The micro reference electrode device of the present embodiment utilizes such properties of the silver / silver chloride electrode.
上述したように、対極３０９及び参照極３１０の２つの電極は第１の微小流路１０７に接続した参照極区画１０３に配置されている。 As described above, the two electrodes of the counter electrode 309 and the reference electrode 310 are arranged in the reference electrode section 103 connected to the first microchannel 107.
本実施形態の微小参照電極デバイスにおいて、参照極区画１０３内の塩素イオン濃度はポテンショスタット５００を使用して一定の値に維持されるようフィードバック制御が行われる。 In the micro reference electrode device of this embodiment, feedback control is performed so that the chlorine ion concentration in the reference electrode section 103 is maintained at a constant value using the potentiostat 500.
ポテンショスタット５００の参照電極用端子５００ａに接続した参照極３１０は、電位を提供する最も重大な電極である。対極３０９は、Ag/AgClの酸化還元反応によってCl-イオンを提供し、もしくは、吸収するために使用される。 The reference electrode 310 connected to the reference electrode terminal 500a of the potentiostat 500 is the most important electrode that provides a potential. The counter electrode 309 is used to provide or absorb Cl 2 − ions by an Ag / AgCl redox reaction.
作用極３０４は、一定の濃度の塩化物イオンを含んでおり、対極３０９及び参照極３１０が備わる参照極区画１０３へ接続する個別の作用極区画１０２に配置されている。 The working electrode 304 contains a fixed concentration of chloride ions and is disposed in a separate working electrode compartment 102 that connects to a reference electrode compartment 103 with a counter electrode 309 and a reference electrode 310.
ポテンショスタット５００は、作用極３０４と参照極３１０との間に生じている静止電位を測定し、これを作用極３０４に印加する。 The potentiostat 500 measures a static potential generated between the working electrode 304 and the reference electrode 310 and applies it to the working electrode 304.
図８は、本実施形態の微小参照電極デバイスにおいて、参照極付近のCl−濃度が増加する場合の負のフィードバックを説明する図である。なお、図中の黒三角は参照極３１０の電位を示し、白三角は作用極３０４の電位を示す。 FIG. 8 is a diagram for explaining negative feedback when the Cl − concentration in the vicinity of the reference electrode increases in the micro reference electrode device of the present embodiment. In the figure, the black triangle indicates the potential of the reference electrode 310, and the white triangle indicates the potential of the working electrode 304.
まず、第１の微小流路１０７中のサンプル液との接触により参照極区画１０３内の参照極３１０付近のCl−濃度が減少する場合を考える。 First, let us consider a case where the Cl − concentration near the reference electrode 310 in the reference electrode section 103 decreases due to contact with the sample liquid in the first microchannel 107.
図８（ａ）に示すように、作用極３０４と参照極３１０との間には、塩化物イオン濃度の差に応じた静電位差（電流が流れていない状態の電極の電位を静止電位といい、その差を静止電位差とする）が生じているとする。この２つの電極付近の作用極区画１０２内及び参照極区画１０３内の塩化物イオン濃度が等しい場合には、電位差は０である。 As shown in FIG. 8A, an electrostatic potential difference (potential of an electrode in a state where no current flows) between the working electrode 304 and the reference electrode 310 is called a resting potential. , The difference is defined as a static potential difference). When the chloride ion concentrations in the working electrode section 102 and the reference electrode section 103 near the two electrodes are equal, the potential difference is zero.
続いて、ポテンショスタット５００によって、作用極３０４と参照極３１０との間にこの静止電位差の値を印加する（図中のResting potential）。この場合には、静止電位差を印加するため、作用極３０４には電流は流れない。 Subsequently, the value of this static potential difference is applied between the working electrode 304 and the reference electrode 310 by the potentiostat 500 (Resting potential in the figure). In this case, no current flows through the working electrode 304 because a static potential difference is applied.
図８（ｂ）に示すように、参照極区画１０３内の塩化物イオン濃度がサンプル液の流入によって希釈されたと仮定すると、ネルンストの式にしたがって、銀／塩化銀である参照極３１０の電位は正（＋）の方向へ上昇する（図中の黒三角）。 As shown in FIG. 8 (b), assuming that the chloride ion concentration in the reference electrode compartment 103 is diluted by the inflow of the sample liquid, the potential of the reference electrode 310, which is silver / silver chloride, according to the Nernst equation is It rises in the positive (+) direction (black triangle in the figure).
このとき、作用極３０４と参照極３１０との間はポテンショスタット５００により電位差が固定されているため（図中のResting potential）、作用極３０４の電位もまた、参照極につられて正（＋）の方向へ上昇する（図中の白三角）。 At this time, since the potential difference between the working electrode 304 and the reference electrode 310 is fixed by the potentiostat 500 (Resting potential in the figure), the potential of the working electrode 304 is also positive (+) with the reference electrode. It rises in the direction of (white triangle in the figure).
ここで、作用極３０４は電解質ゲル４００などで密封されているため作用極区画１０２内の塩化物イオン濃度は常に一定である。そのため、過電圧が作用極３０４にかかり、さらに、過電圧によって対極３０９と作用極３０４との間には正の大電流が流れることとなる（図中のGenerated current）。 Here, since the working electrode 304 is sealed with the electrolyte gel 400 or the like, the chloride ion concentration in the working electrode section 102 is always constant. Therefore, an overvoltage is applied to the working electrode 304, and a large positive current flows between the counter electrode 309 and the working electrode 304 due to the overvoltage (Generated current in the figure).
このとき、ポテンショスタット５００では作用極３０４で流れる逆符号の電流が対極３０９に流れることとなるため、対極３０９上では負の大電流が流れることとなるが、対極３０９もまた、銀／塩化銀電極であるため、対極３０９ではAgCl + e− → Ag + Cl−のような反応が生じ、塩化物イオンが発生する。 At this time, in the potentiostat 500, a current having an opposite sign flowing at the working electrode 304 flows to the counter electrode 309, so that a large negative current flows on the counter electrode 309, but the counter electrode 309 also has silver / silver chloride. Since it is an electrode, a reaction such as AgCl + e − → Ag + Cl − occurs at the counter electrode 309, and chloride ions are generated.
この結果、図８（ｃ）に示すように、参照極区画１０３の塩化物イオン濃度が上昇し、その結果、参照極３１０の電位が元の位置に戻る（図中のRecovered to the initial [Cl-]）。元の位置に戻ると電流も収まり、電極反応も停止する。 As a result, as shown in FIG. 8C, the chloride ion concentration in the reference electrode section 103 increases, and as a result, the potential of the reference electrode 310 returns to the original position (Recovered to the initial [Cl - ]). When it returns to its original position, the current stops and the electrode reaction stops.
このように、参照極３１０付近の塩化物イオン濃度の変化に応じた、自動的なフィードバックにより参照極区画１０３内の塩化物イオン濃度が一定となる。つまり、作用極の正（負）方向への変化を対極の負（正）方向の反応が打ち消すため、これを負のフィードバックという。 As described above, the chloride ion concentration in the reference electrode section 103 becomes constant by automatic feedback according to the change in the chloride ion concentration in the vicinity of the reference electrode 310. That is, since the reaction in the negative (positive) direction of the counter electrode cancels the change in the positive (negative) direction of the working electrode, this is called negative feedback.
図９は、本実施形態の微小参照電極デバイスにおいて、参照極区画内の参照極付近のCl−濃度が減少する場合の負のフィードバックを説明する図である。 FIG. 9 is a diagram for explaining negative feedback when the Cl − concentration in the vicinity of the reference electrode in the reference electrode section decreases in the micro reference electrode device of the present embodiment.
参照極区画１０３内の参照極３１０付近のCl−濃度が増加する場合には、図９（ａ）に示すように逆方向に電位が変化し、図９（ｂ）に示すように、作用極３０４の銀／塩化銀には過電圧がかかり、負の大電流が流れる。そして、対極３０９上ではAg + Cl → AgCl + e−の変化が生じる。すなわち、塩素イオンは対極３０９上で消費され、図９（ｃ）に示すように、参照極区画１０３内の参照極３１０付近のCl−濃度が低下し、同様に参照極３１０の電位が一定に維持される。 When the Cl − concentration in the vicinity of the reference electrode 310 in the reference electrode section 103 increases, the potential changes in the reverse direction as shown in FIG. 9A, and the working electrode as shown in FIG. 9B. An overvoltage is applied to the silver / silver chloride of 304, and a large negative current flows. On the counter electrode 309, a change of Ag + Cl → AgCl + e − occurs. That is, chlorine ions are consumed on the counter electrode 309, and as shown in FIG. 9C, the Cl − concentration in the vicinity of the reference electrode 310 in the reference electrode section 103 decreases, and similarly, the potential of the reference electrode 310 becomes constant. Maintained.
図１０は、本実施形態の微小参照電極デバイス１を評価した結果を示す図である。このデバイスの機能を評価するため、参照極区画１０３に0.1 Mあるいは50 mMのKClを満たし、第１の微小流路１０７に50 mMあるいは10 mMのKClを流した。 FIG. 10 is a diagram showing a result of evaluating the micro reference electrode device 1 of the present embodiment. In order to evaluate the function of this device, the reference electrode compartment 103 was filled with 0.1 M or 50 mM KCl, and 50 mM or 10 mM KCl was passed through the first microchannel 107.
参照極３１０付近のKClは速やかに希釈され、参照極３１０の電位は正の方向に変化し、図中の「ＯＦＦ」の線に示すように、最終的に希釈された濃度に対応する電位に落ち着いた。これより、単純に銀／塩化銀電極を微小な区画に置いただけでは、使用に耐えうる参照電極を実現することが極めて難しいことがわかる。 The KCl in the vicinity of the reference electrode 310 is quickly diluted, and the potential of the reference electrode 310 changes in the positive direction. As shown by the “OFF” line in the figure, the potential finally corresponds to the diluted concentration. Calm down. From this, it can be seen that it is extremely difficult to realize a reference electrode that can withstand use by simply placing a silver / silver chloride electrode in a minute compartment.
一方、ポテンショスタットによりフィードバックをかけると、図中の「ＯＮ」の線に示すように、参照極区画中のCl−濃度が一定に維持され、参照極電位が安定し、変動は最大でも3 mV以内であった。よって、本実施形態の微小参照電極デバイスの妥当性が証明された。 On the other hand, when feedback is applied by a potentiostat, the Cl − concentration in the reference electrode section is kept constant, the reference electrode potential is stable, and the fluctuation is 3 mV at the maximum, as shown by the “ON” line in the figure. Was within. Therefore, the validity of the micro reference electrode device of this embodiment was proved.
以上は参照極の説明であったが、実際にはこれとさらに他の電極を組み合わせて使用する。例えば、イオン濃度を測定する場合には、微小流路内にイオンを検出するための指示電極を形成し、前期参照極３１０の電位を基準にして、この指示電極の電位を測定すれば良い。電位はイオン濃度の対数に比例して変化するので、電位よりイオン濃度が求まる。 The above is the description of the reference electrode, but actually, this is used in combination with another electrode. For example, when measuring the ion concentration, an indicator electrode for detecting ions is formed in the microchannel, and the potential of the indicator electrode may be measured using the potential of the reference electrode 310 as a reference. Since the potential changes in proportion to the logarithm of the ion concentration, the ion concentration can be obtained from the potential.
１：微小参照電極デバイス
１００：ＰＤＭＳ基板
１０１：注入口
１０２：作用極区画
１０３：参照極区画
１０４：参照極用溶液注入ポート
１０５：第１のサンプル注入ポート１０５
１０６：第２のサンプル注入ポート１０６
１０７：第１の微小流路
１０８：第２の微小流路
１０９：第２の液絡路
１１０：第１の液絡路
２００：絶縁層
２０１：作用極導通部２０１
２０２：対極・参照極導通部２０２
２０３：対極導通部
２０４：参照極被覆部
２０５：参照極導通部
３００：ガラス基板
３０１：対極用パッド
３０２：作用極用パッド
３０３：参照極用パッド
３０４：作用極
３０５：対極・参照極部
３０６：配線パターン
３０７：配線パターン
３０８：配線パターン
３０９：対極
３１０：参照極
４００：ポテンショスタット
1: Micro-reference electrode device 100: PDMS substrate 101: Injection port 102: Working electrode compartment 103: Reference electrode compartment 104: Reference electrode solution injection port 105: First sample injection port 105
106: Second sample injection port 106
107: first microchannel 108: second microchannel 109: second liquid interface 110: first liquid interface 200: insulating layer 201: working electrode conduction unit 201
202: Counter electrode / reference electrode conductive portion 202
203: Counter electrode conducting portion 204: Reference electrode covering portion 205: Reference electrode conducting portion 300: Glass substrate 301: Counter electrode pad 302: Working electrode pad 303: Reference electrode pad 304: Working electrode 305: Counter electrode / reference electrode portion 306 : Wiring pattern 307: Wiring pattern 308: Wiring pattern 309: Counter electrode 310: Reference electrode 400: Potentiostat
Claims (7)
参照極及び対極が配置され、所定の電解液を収容し、第１の液絡路を介して前記作用極区画内の電解液と電解液の接触が図られるともに、第２の液絡路を介して計測対象となる液体と電解液の接触が図られた参照極区画と、
を備え、
前記作用極と前記参照極との電位差を固定し、前記参照極区画内の電解液における所定のイオン濃度が変化した場合に前記作用極に生じる電流と逆符号の電流を前記対極に流し、前記参照極区画内の所定のイオン濃度を一定とする
ことを特徴とする微小参照電極デバイス。 A working electrode compartment in which a working electrode is disposed and contains a predetermined electrolyte;
A reference electrode and a counter electrode are arranged, accommodates a predetermined electrolytic solution, allows contact between the electrolytic solution in the working electrode compartment and the electrolytic solution through the first liquid junction, and the second liquid junction A reference electrode section in which contact between the liquid to be measured and the electrolyte is achieved,
With
A potential difference between the working electrode and the reference electrode is fixed, and when a predetermined ion concentration in the electrolyte solution in the reference electrode section changes, a current having a sign opposite to that generated in the working electrode is passed through the counter electrode, A micro reference electrode device characterized in that a predetermined ion concentration in a reference electrode section is constant.
参照極及び対極が配置され、所定の電解液を収容し、第１の液絡路を介して前記作用極区画内の電解液と電解液の接触が図られるともに、第２の液絡路を介して計測対象となる液体と電解液の接触が図られた参照極区画と、
を備える微小参照電極デバイスの制御方法であって、
前記作用極と前記参照極との電位差を固定し、前記参照極区画内の電解液における所定のイオン濃度が変化した場合に前記作用極に生じる電流と逆符号の電流を前記対極に流し、前記参照極区画内の所定のイオン濃度を一定とする
ことを特徴とする方法。
A working electrode compartment in which a working electrode is disposed and contains a predetermined electrolyte;
A reference electrode and a counter electrode are arranged, accommodates a predetermined electrolytic solution, allows contact between the electrolytic solution in the working electrode compartment and the electrolytic solution through the first liquid junction, and the second liquid junction A reference electrode section in which contact between the liquid to be measured and the electrolyte is achieved,
A method for controlling a micro reference electrode device comprising:
A potential difference between the working electrode and the reference electrode is fixed, and when a predetermined ion concentration in the electrolyte solution in the reference electrode section changes, a current having a sign opposite to that generated in the working electrode is passed through the counter electrode, A method characterized in that the predetermined ion concentration in the reference electrode compartment is constant.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20120217159A1 (en) * | 2011-02-28 | 2012-08-30 | Institute For Molecular Medicine, Inc. | Method and apparatus for measuring oxidation-reduction potential |
| US9372167B2 (en) | 2012-04-19 | 2016-06-21 | Aytu Bioscience, Inc. | Oxidation-reduction potential test device including a multiple layer gel |
| US9410913B2 (en) | 2012-10-23 | 2016-08-09 | Aytu Bioscience, Inc. | Methods and systems for measuring and using the oxidation-reduction potential of a biological sample |
| JP2016212095A (en) * | 2015-04-30 | 2016-12-15 | スティヒティング・イメック・ネーデルラントＳｔｉｃｈｔｉｎｇ ＩＭＥＣ Ｎｅｄｅｒｌａｎｄ | Reference electrode with pore membrane |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001004581A (en) * | 1999-06-24 | 2001-01-12 | Sentan Kagaku Gijutsu Incubation Center:Kk | Very small reference electrode |
| JP2007163441A (en) * | 2005-12-16 | 2007-06-28 | Nippon Telegr & Teleph Corp <Ntt> | Electrochemical measuring microelectrode and electrochemical measuring method |
-
2008
- 2008-10-20 JP JP2008270073A patent/JP5164164B2/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001004581A (en) * | 1999-06-24 | 2001-01-12 | Sentan Kagaku Gijutsu Incubation Center:Kk | Very small reference electrode |
| JP2007163441A (en) * | 2005-12-16 | 2007-06-28 | Nippon Telegr & Teleph Corp <Ntt> | Electrochemical measuring microelectrode and electrochemical measuring method |
Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2014507008A (en) * | 2011-02-28 | 2014-03-20 | ルオクシス ダイアグノスティクス インコーポレイテッド | Method and apparatus for measuring redox potential |
| US20120217159A1 (en) * | 2011-02-28 | 2012-08-30 | Institute For Molecular Medicine, Inc. | Method and apparatus for measuring oxidation-reduction potential |
| US8317997B2 (en) * | 2011-02-28 | 2012-11-27 | Institute For Molecular Medicine, Inc. | Method and apparatus for measuring oxidation-reduction potential |
| US8329012B2 (en) * | 2011-02-28 | 2012-12-11 | Institute For Molecular Medicine, Inc. | Method and apparatus for measuring oxidation-reduction potential |
| CN103299181A (en) * | 2011-02-28 | 2013-09-11 | 卢奥克西斯诊断股份有限公司 | Method and apparatus for measuring redox potential |
| US8641888B2 (en) | 2011-02-28 | 2014-02-04 | Luoxis Diagnostics, Inc. | Method and apparatus for measuring oxidation-reduction potential |
| US20120217173A1 (en) * | 2011-02-28 | 2012-08-30 | Institute For Molecular Medicine, Inc. | Method and apparatus for measuring oxidation-reduction potential |
| CN103299181B (en) * | 2011-02-28 | 2015-04-08 | 卢奥克西斯诊断股份有限公司 | Method and apparatus for measuring redox potential |
| US9528959B2 (en) | 2011-02-28 | 2016-12-27 | Aytu Bioscience, Inc. | Method and apparatus for measuring oxidation-reduction potential |
| US9034159B2 (en) | 2011-02-28 | 2015-05-19 | Luoxis Diagnostics, Inc. | Method and apparatus for measuring oxidation-reduction potential |
| US9372167B2 (en) | 2012-04-19 | 2016-06-21 | Aytu Bioscience, Inc. | Oxidation-reduction potential test device including a multiple layer gel |
| US10281425B2 (en) | 2012-04-19 | 2019-05-07 | Aytu Bioscience, Inc. | Multiple layer gel |
| US9410913B2 (en) | 2012-10-23 | 2016-08-09 | Aytu Bioscience, Inc. | Methods and systems for measuring and using the oxidation-reduction potential of a biological sample |
| JP2016212095A (en) * | 2015-04-30 | 2016-12-15 | スティヒティング・イメック・ネーデルラントＳｔｉｃｈｔｉｎｇ ＩＭＥＣ Ｎｅｄｅｒｌａｎｄ | Reference electrode with pore membrane |
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