JPH0430544B2 - - Google Patents
Info
- Publication number
- JPH0430544B2 JPH0430544B2 JP58152627A JP15262783A JPH0430544B2 JP H0430544 B2 JPH0430544 B2 JP H0430544B2 JP 58152627 A JP58152627 A JP 58152627A JP 15262783 A JP15262783 A JP 15262783A JP H0430544 B2 JPH0430544 B2 JP H0430544B2
- Authority
- JP
- Japan
- Prior art keywords
- oxygen
- electrode
- tip surface
- solution
- measurement
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000001301 oxygen Substances 0.000 claims description 61
- 229910052760 oxygen Inorganic materials 0.000 claims description 61
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 58
- 239000003575 carbonaceous material Substances 0.000 claims description 9
- -1 poly(hydroxyethyl methacrylate) Polymers 0.000 claims description 8
- 229920002338 polyhydroxyethylmethacrylate Polymers 0.000 claims description 8
- 229920006254 polymer film Polymers 0.000 claims description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 6
- 239000012466 permeate Substances 0.000 claims description 2
- 238000005259 measurement Methods 0.000 description 19
- 239000000243 solution Substances 0.000 description 15
- 239000012488 sample solution Substances 0.000 description 10
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 6
- 238000002474 experimental method Methods 0.000 description 6
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 6
- 239000007789 gas Substances 0.000 description 5
- 229920005597 polymer membrane Polymers 0.000 description 5
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 4
- WOBHKFSMXKNTIM-UHFFFAOYSA-N Hydroxyethyl methacrylate Chemical compound CC(=C)C(=O)OCCO WOBHKFSMXKNTIM-UHFFFAOYSA-N 0.000 description 4
- 229910001882 dioxygen Inorganic materials 0.000 description 4
- 229920002239 polyacrylonitrile Polymers 0.000 description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 3
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 3
- 239000007864 aqueous solution Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 239000003822 epoxy resin Substances 0.000 description 3
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 150000002926 oxygen Chemical class 0.000 description 3
- 229920000647 polyepoxide Polymers 0.000 description 3
- 230000035945 sensitivity Effects 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- 229920000049 Carbon (fiber) Polymers 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 239000008280 blood Substances 0.000 description 2
- 210000004369 blood Anatomy 0.000 description 2
- 239000004917 carbon fiber Substances 0.000 description 2
- ZOMNIUBKTOKEHS-UHFFFAOYSA-L dimercury dichloride Chemical class Cl[Hg][Hg]Cl ZOMNIUBKTOKEHS-UHFFFAOYSA-L 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229910000510 noble metal Inorganic materials 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- 239000010970 precious metal Substances 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 241000894007 species Species 0.000 description 2
- 238000011144 upstream manufacturing Methods 0.000 description 2
- 241000283690 Bos taurus Species 0.000 description 1
- 239000000020 Nitrocellulose Substances 0.000 description 1
- 229920000297 Rayon Polymers 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical class [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 229940075397 calomel Drugs 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- 239000000571 coke Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 238000002484 cyclic voltammetry Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000005868 electrolysis reaction Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229920001220 nitrocellulos Polymers 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 description 1
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 description 1
- 102000004169 proteins and genes Human genes 0.000 description 1
- 108090000623 proteins and genes Proteins 0.000 description 1
- 239000002964 rayon Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 235000000346 sugar Nutrition 0.000 description 1
- 150000008163 sugars Chemical class 0.000 description 1
- 229920005992 thermoplastic resin Polymers 0.000 description 1
- 229920001187 thermosetting polymer Polymers 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/403—Cells and electrode assemblies
- G01N27/404—Cells with anode, cathode and cell electrolyte on the same side of a permeable membrane which separates them from the sample fluid, e.g. Clark-type oxygen sensors
Landscapes
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Physics & Mathematics (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Molecular Biology (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Inert Electrodes (AREA)
- Measurement Of The Respiration, Hearing Ability, Form, And Blood Characteristics Of Living Organisms (AREA)
Description
〔技術分野〕
この発明は酸素濃度測定用センサーに係り、特
には、溶液中の溶存酸素濃度を電流応答で測定す
るためのセンサーに関する。
〔先行技術および問題点〕
従来から使用されている酸素センサーあるいは
酸素電極は、電極系の分類から両極分離型電極と
クラーク型電極とに大別される。
両極分離型電極は白金等の貴金属の表面を高分
子膜で被覆したセンサー部を有し、溶存酸素測定
液に直接浸漬して用いる。このタイプの酸素電極
は微小化が容易ではあるものの、貴金属を用いて
いるため高価であり、また測定液中において貴金
属表面上に高分子膜を長時間保持しておくことが
容易でないため耐久性に劣るという欠点がある。
クラーク型電極は白金製陰極と銀製陽極とが、
測定液から高分子膜で隔てられた内部電解液室内
に浸漬されている構造のものであり、内部電解液
室を必要とするので微小化が困難である。また、
このタイプの電極もセンサー部に高価な貴金属材
料を用いている。
発明の目的
従つてこの発明の目的は、微小化が可能であ
り、比較的安価な材料で作製でき、しかも耐久性
に優れた、酸素濃度測定用センサーを提供するこ
とにある。
この発明によれば、露出先端面を有し、該先端
面以外の全側面が絶縁された、酸素と反応する電
極部を有する酸素濃度測定用微小センサーであつ
て、該電極部は、単一の細長の柱状又は繊維状の
導電性炭素材料からなり、該電極部の該露出先端
面は、ポリ（メタクリル酸ヒドロキシエチル）か
らなる、酸素分子及び水分子を透過させる高分子
膜で覆われていることを特徴とする酸素濃度測定
用微小センサーが提供される。
発明の具体的説明
以下、この発明を図面を参照しつつ詳しく説明
する。
第１図に示すように、この発明の酸素濃度測定
用センサ（以下、酸素センサーという）１０は導
電性炭素材料で形成された本体１１を備え、その
表面には酸素分子および水分子を透過させる高分
子膜１２が形成されている。図示の例では単一の
細長の柱状もしくは繊維状炭素材料の周囲をエポ
キシ樹脂等の酸素分子および水分子不透過性の絶
縁材１３で被覆し、本体１１の露出先端面のみ高
分子膜１２が被着されている。なお、本体１１の
先端面の面積は、0.2mm2以下であることが好まし
い。
しかしながら、本体１１は細長の柱状または特
に繊維状炭素材料を束ねたもので構成されていて
もよい。
本体１１を構成する炭素材料の具体例を挙げる
と、ピツチ、コークスをバインダーと混ぜ焼結し
たもの、ポリアクリロニトリルせんい、レーヨン
せんいの焼結体、非溶解性高分子（セルロース
系）、熱硬化性樹脂）焼結体または導電性物質表
面に揮発性有機物（メタン、プロピレン、ベンゼ
ン等）を表面改質（CVD法、熱処理法、触媒を
利用して表面改質を行う）させたもの等である。
高分子膜１２としては、ポリ（メタクリル酸ヒ
ドロキシエチル）の膜が用いられる。これら高分
子膜は溶液中への浸漬、真空蓄積（蒸着、スパツ
タ等）等の手法により本体１１表面に形成するこ
とができ、本体１１との密着性は極めてよい。
発明の具体的作用
以上述べたこの発明の酸素センサーを用いて水
溶液中の溶存酸素濃度を測定するためには、測定
溶液に浸漬される作用極としてこの発明の酸素セ
ンサーを用い、対極として白金網、および基準電
極として飽和カロメル電極を用いてポテンシオス
タツトと呼ばれる定電位電解装置に組み込むとよ
い。酸素の還元電位に相当する電圧をこの発明の
酸素センサーに印加し、その時の還元電流値に基
いて水溶液中の溶存酸素濃度を知ることができ
る。還元電流値が一定になるまでの時間（応答速
度）は溶存酸素が高分子膜を通過し本体表面に達
するまでの速度に依存する。したがつて測定溶液
を撹拌することによつて応答速度を早めることが
できる。
実施例 １
ポリアクリロニトリル（PAN）からの炭素繊
維（径７〜8μm）を約100本束ね、側面を絶縁し、
これをポリ（メタクリル酸ヒドロキシエチル）
（PHEMA）のメタノール溶液に浸漬し、引き揚
げて乾燥すること３回おこなつた。こうして、長
さ約20mm、直径１mmの酸素センサーを作製した。
この酸素センサーを作用極、白金網を対極、お
よび飽和塩化ナトリウムカロメル電極（SSCE）
を基準電極として用いポテンシオスタツトに組み
込み、第２図に示す測定系によつて溶存酸素分圧
の測定実験を以下の通りおこなつた。測定水溶液
（PH6.0）の組成は0.2モル／NaClO4、20ミリモ
ル／ NaH2PO4および30ミリモル／
Na2HPO4であり、測定温度は37±0.1℃であつ
た。
第２図に示す測定系は、作用極１１′、対極１
２′および基準電極１３′が挿入されている測定セ
ル１４を備えている。試料溶液はラインL1で構
成される閉回路中を矢印で示す方向にポンプＰで
循環される。ラインL1内で測定セルの上流側に
は試料溶液槽１５が設けられており、その中には
市販の酸素電極１６と温度計１７が設置されてい
る。ラインL1内で試料溶液槽１５の上流側には
人工肺１８が設けられている。窒素ボンベ２１、
酸素ボンベ２２および炭酸ガスボンベ２３からの
ガスはそれぞれラインL7，L8およびL9を通つて
ガス混合器２４に入り、そこで必要に応じて混合
され、ラインL3を通つて人工肺１８に至り、そ
こを通過する試料溶液にガスを供給し、余剰のガ
スはラインL4から排出される。人工肺中の温度
を一定にすべく恒温水がラインL5から導入され
ラインL6から排出される。測定セル１４の両側
には三方弁１９および２０が設けられており、そ
の間にバイパスラインL2が形成されている。作
用極１１′、対極１２′および基準電１３′はそれ
ぞれリード線２５，２６および２７を介してポテ
ンシオスタツト２９に接続されている。市販の酸
素電極１６はリード線２８を介してイオンメータ
ー３０に接続されている。ポテンシオスタツト２
９と酸素濃度測定装置３０とはレコーダー３１に
接続されている。
＜実験例 １＞
最初に試料溶液中に酸素ガスを125mm／分の割
合で導入し、電圧掃引速度50mV／秒で作用極１
１′に0.0から−1.0V（対SSCE）まで変化させ、サ
イクリツクボルタモメトリーにより検討した。測
定溶液中に713mmHgの酸素が溶存していたとき、
酸素の還元波が−0.7V（対SSCE）に現われ、一
方、この測定溶液に酸素ガスのみを導入して脱酸
素すると還元波は消失した。こうして、−0.7V付
近で酸素の還元ピークが生起することを確認し
た。
次に、人工肺１８へのガス全流量を125ml／分
と一定にし、酸素ガス流量と窒素ガス流量のみを
変化させることによつて酸素分圧を変え、作用極
への印加電圧を−0.8V（対SSCE）と一定にして
実験をおこなつた。このときの還元電流（μA）
値を溶存酸素分圧Po2（市販酸素電極１６で測定）
に対してプロツトすると第３図に示すように直線
関係が得られた。この結果この発明の電極は電流
応答で溶存酸素量を測定できることがわかつた。
＜比較実験例＞
PHEMAで被覆しないPAN炭素繊維を用いた
以外は実験例１と同様に操作したところ、還元電
流は安定せず、測定が困難であつた。
＜実験例 ２＞
溶存酸素ガス分圧を156mmHgと一定にし、測定
試料溶液中にK3FeCN）6をそれぞれ１×10-4、１
×10-3、２×10-3、５×10-3および１×10-2モ
ル／の割合で添加し、それぞれの場合における
還元電流値を測定すると、第４図中線Ｂにおける
点ａ，ｂ，ｃ，ｄおよびｅで示されるように、
K3Fe（CN）6濃度の増加につれて還元電流値が増
大した。したがつて、測定溶液中の酸化還元種の
影響を受けることが判明した。
次に、K3Fe（CN）6の濃度を一定（１×10-2モ
ル／）とし、溶存酸素分圧（Po2）を減少させ
てゆき、その時の還元電流値をPo2に対してプロ
ツトすると第４図中線Ｃで示されるように直線関
係が得られた。この直線の勾配は、K3Fe（CN）6
無添加の場合の直線（第４図中線Ａ）の勾配とほ
ぼ同じであつた。このことから、酸化還元種の有
無にかかわらず、二点較正法により、溶存酸素分
圧を知ることができることがわかつた。
＜実験例 ３＞
PH6.84のリン酸緩緩液を用いた以外は実験例１
と同様にして実験をおこない、応答速度を調べ
た。まず、Po2変化前の試料溶液を三方弁１９お
よび２０の操作によつて測定セル１４に貯めた
後、バイパスラインL2に試料溶液を流すように
する。次に、Po2を変化させ、試料溶液中の溶存
酸素分圧が一定になるのを市販酸素電極１６で確
認した後、三方弁１９，２０の操作によりその試
料溶液を測定セル１４中に流速100ml／分で流す。
この時点からこの発明の酸素センサー１１′に流
れる還元電流の値が一定になるまでの時間（応答
時間）を測定した。結果を表１に示す。
[Technical Field] The present invention relates to a sensor for measuring oxygen concentration, and more particularly to a sensor for measuring dissolved oxygen concentration in a solution using current response. [Prior Art and Problems] Conventionally used oxygen sensors or oxygen electrodes are broadly classified into bipolar separation type electrodes and Clark type electrodes based on the classification of electrode systems. The bipolar separation type electrode has a sensor part made of a noble metal such as platinum whose surface is coated with a polymer membrane, and is used by being directly immersed in a solution for measuring dissolved oxygen. Although this type of oxygen electrode is easy to miniaturize, it is expensive because it uses a precious metal, and it is not easy to maintain the polymer film on the surface of the precious metal for a long time in the measurement solution, so it is not durable. It has the disadvantage of being inferior to The Clark type electrode has a platinum cathode and a silver anode.
It has a structure in which it is immersed in an internal electrolyte chamber separated from the measurement solution by a polymer membrane, and requires an internal electrolyte chamber, making it difficult to miniaturize. Also,
This type of electrode also uses expensive noble metal materials for the sensor part. OBJECTS OF THE INVENTION Accordingly, an object of the present invention is to provide a sensor for measuring oxygen concentration that can be miniaturized, can be manufactured from relatively inexpensive materials, and has excellent durability. According to the present invention, there is provided a microsensor for measuring oxygen concentration, which has an electrode portion that reacts with oxygen and has an exposed tip surface and is insulated on all sides other than the tip surface, wherein the electrode portion has a single The exposed tip surface of the electrode part is covered with a polymer film made of poly(hydroxyethyl methacrylate) that allows oxygen molecules and water molecules to permeate. A microsensor for measuring oxygen concentration is provided. DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to the drawings. As shown in FIG. 1, an oxygen concentration measuring sensor (hereinafter referred to as an oxygen sensor) 10 of the present invention includes a main body 11 made of a conductive carbon material, the surface of which is permeable to oxygen molecules and water molecules. A polymer film 12 is formed. In the illustrated example, the periphery of a single elongated columnar or fibrous carbon material is covered with an insulating material 13 impermeable to oxygen molecules and water molecules, such as epoxy resin, and the polymer film 12 is coated only on the exposed tip surface of the main body 11. It is covered. Note that the area of the tip surface of the main body 11 is preferably 0.2 mm 2 or less. However, the main body 11 may also be constructed in the form of an elongated column or, in particular, in a bundle of fibrous carbon material. Specific examples of carbon materials constituting the main body 11 include pitch, coke mixed with a binder and sintered, polyacrylonitrile fiber, sintered rayon fiber, insoluble polymer (cellulose), and thermosetting material. Resin) sintered bodies or conductive materials whose surfaces are surface-modified with volatile organic substances (methane, propylene, benzene, etc.) (surface modification is performed using CVD, heat treatment, or catalysts). . As the polymer film 12, a poly(hydroxyethyl methacrylate) film is used. These polymer films can be formed on the surface of the main body 11 by methods such as immersion in a solution or vacuum accumulation (evaporation, sputtering, etc.), and have extremely good adhesion to the main body 11. Specific Effects of the Invention In order to measure the dissolved oxygen concentration in an aqueous solution using the oxygen sensor of this invention described above, the oxygen sensor of this invention is used as a working electrode that is immersed in a measurement solution, and a platinum wire mesh is used as a counter electrode. , and a saturated calomel electrode as a reference electrode, and may be incorporated into a constant potential electrolysis device called a potentiostat. A voltage corresponding to the reduction potential of oxygen is applied to the oxygen sensor of the present invention, and the dissolved oxygen concentration in the aqueous solution can be determined based on the reduction current value at that time. The time it takes for the reduction current value to become constant (response speed) depends on the speed at which dissolved oxygen passes through the polymer membrane and reaches the surface of the main body. Therefore, by stirring the measurement solution, the response speed can be increased. Example 1 Approximately 100 carbon fibers (diameter 7 to 8 μm) made from polyacrylonitrile (PAN) were bundled, the sides were insulated,
This is poly(hydroxyethyl methacrylate)
It was immersed in a methanol solution of (PHEMA), pulled out and dried three times. In this way, an oxygen sensor with a length of about 20 mm and a diameter of 1 mm was fabricated. This oxygen sensor is used as a working electrode, a platinum wire mesh as a counter electrode, and a saturated sodium chloride calomel electrode (SSCE).
was incorporated into a potentiostat using as a reference electrode, and an experiment to measure dissolved oxygen partial pressure was conducted as follows using the measurement system shown in FIG. The composition of the measurement aqueous solution (PH6.0) was 0.2 mol/NaClO 4 , 20 mmol/NaH 2 PO 4 and 30 mmol/
It was Na 2 HPO 4 and the measurement temperature was 37±0.1°C. The measurement system shown in Fig. 2 consists of a working electrode 11' and a counter electrode 1.
2' and a measuring cell 14 into which a reference electrode 13' is inserted. The sample solution is circulated by a pump P in the direction indicated by the arrow in a closed circuit constituted by line L1 . A sample solution tank 15 is provided on the upstream side of the measurement cell within the line L1 , and a commercially available oxygen electrode 16 and a thermometer 17 are installed therein. An oxygenator 18 is provided upstream of the sample solution tank 15 within the line L1 . Nitrogen cylinder 21,
The gases from the oxygen cylinder 22 and the carbon dioxide cylinder 23 enter the gas mixer 24 through lines L 7 , L 8 and L 9 respectively, where they are mixed as required and are passed through the line L 3 to the oxygenator 18. , supplies gas to the sample solution passing through it, and excess gas is discharged through line L 4 . Constant temperature water is introduced from line L5 and discharged from line L6 to maintain a constant temperature in the oxygenator. Three-way valves 19 and 20 are provided on both sides of the measuring cell 14, between which a bypass line L2 is formed. Working electrode 11', counter electrode 12' and reference electrode 13' are connected to potentiostat 29 via lead wires 25, 26 and 27, respectively. A commercially available oxygen electrode 16 is connected to an ion meter 30 via a lead wire 28. potentiostat 2
9 and the oxygen concentration measuring device 30 are connected to a recorder 31. <Experimental example 1> First, oxygen gas was introduced into the sample solution at a rate of 125 mm/min, and the working electrode 1 was introduced at a voltage sweep rate of 50 mV/sec.
1' from 0.0 to -1.0V (vs. SSCE) and examined by cyclic voltammometry. When 713 mmHg of oxygen was dissolved in the measurement solution,
An oxygen reduction wave appeared at −0.7V (vs. SSCE), but when only oxygen gas was introduced into the measurement solution to deoxidize it, the reduction wave disappeared. In this way, it was confirmed that an oxygen reduction peak occurred around -0.7V. Next, the total gas flow rate to the oxygenator 18 was kept constant at 125 ml/min, the oxygen partial pressure was changed by changing only the oxygen gas flow rate and the nitrogen gas flow rate, and the voltage applied to the working electrode was set to −0.8 V. (vs. SSCE) and was kept constant during the experiment. Reduced current (μA) at this time
The value is dissolved oxygen partial pressure Po 2 (measured with commercially available oxygen electrode 16)
When plotted against , a linear relationship was obtained as shown in FIG. As a result, it was found that the electrode of the present invention can measure the amount of dissolved oxygen based on current response. <Comparative Experimental Example> When the same operation as in Experimental Example 1 was performed except that PAN carbon fiber not coated with PHEMA was used, the reduction current was not stable and measurement was difficult. <Experimental example 2> The dissolved oxygen gas partial pressure was kept constant at 156 mmHg, and K 3 FeCN) 6 was added at 1×10 -4 and 1 in the measurement sample solution, respectively.
×10 -3 , 2 × 10 -3 , 5 × 10 -3 and 1 × 10 -2 mol/, and when the reduction current values in each case were measured, point a on line B in Figure 4 was obtained. , b, c, d and e,
The reduction current value increased as the K 3 Fe(CN) 6 concentration increased. Therefore, it was found that the measurement was affected by the redox species in the measurement solution. Next, the concentration of K 3 Fe (CN) 6 is kept constant (1 × 10 -2 mol/), the dissolved oxygen partial pressure (Po 2 ) is decreased, and the reduction current value at that time is changed to Po 2 . When plotted, a linear relationship was obtained as shown by line C in FIG. The slope of this straight line is K3Fe (CN) 6
The slope was almost the same as the slope of the straight line (line A in Figure 4) in the case of no additive. From this, it was found that the dissolved oxygen partial pressure can be determined by the two-point calibration method regardless of the presence or absence of redox species. <Experimental example 3> Experimental example 1 except that a phosphoric acid loosening solution with a pH of 6.84 was used.
An experiment was conducted in the same manner as above, and the response speed was investigated. First, the sample solution before Po 2 change is stored in the measurement cell 14 by operating the three-way valves 19 and 20, and then the sample solution is allowed to flow through the bypass line L2 . Next, after changing Po 2 and confirming that the dissolved oxygen partial pressure in the sample solution becomes constant using a commercially available oxygen electrode 16, the flow rate of the sample solution into the measurement cell 14 is increased by operating the three-way valves 19 and 20. Flow at 100ml/min.
The time (response time) from this point until the value of the reduction current flowing through the oxygen sensor 11' of the present invention became constant was measured. The results are shown in Table 1.
【表】
実施例 ２
牛血を用いた以外は実験例１と同様に操作をお
こなつた。還元電流値と溶存酸素分圧との関係は
第５図に示すように直線関係にあつた。血液中に
存在する夾雑イオンの透過や糖、タンパク質等の
電極への吸着を生じることなく測定がおこなえ
た。なお、酸素センサーの感度は−3.5×10-9A／
mmHgであつた。
参考例
PHEMA溶液の代りにニトロセルロースのア
セトン溶液を用いた以外は実施例１と同様にして
酸素センサーを作製し、これを用いて実験例１と
同様に実験をおこなつた。結果を第６図に示す。
感度は−1.35×10-9A／mmHgであり、従来の酸素
センサーようも10倍程度高かつた。
実施例 ３
導電性炭素材料としてシヤープペン用の芯（ピ
ツチなどの骨剤に熱可塑樹脂を混ぜ焼結させたも
の）（HB，径0.5mm）の周囲をエポキシ樹脂で絶
縁し、露出先端面をシリコンカーバイド紙で研磨
し、水洗した。その先端面にPHEMAのメタノ
ール溶液を塗布し乾燥して酸素センサーを作製し
た。サイクリツクボルタモメトリーによる検討に
より、−0.7V（対SSCE）付近に酸素の還元波が現
われることを確認した。
この酸素センサーを用い、−1.0V（対SSCE）の
電圧を印加した以外は実験例１と同様の実験をお
こなつた。溶存酸素分圧と還元電流値との関係は
第７図に示すように直線関係にあつた。
発明の具体的効果
以上述べたように、この発明によれば、安価な
炭素材料で作製でき、しかも応答速度も早く、感
度の良好な酸素センサーが提供される。炭素材料
と高分子膜の密着性は極めて良好であるので、こ
の酸素センサーは耐久性に優れる。また、炭素材
料の加工限度まで微小化できる。[Table] Example 2 The same procedure as in Experimental Example 1 was performed except that bovine blood was used. The relationship between the reduction current value and the dissolved oxygen partial pressure was a linear relationship as shown in FIG. Measurements were possible without permeation of contaminant ions present in blood or adsorption of sugars, proteins, etc. to the electrode. The sensitivity of the oxygen sensor is -3.5×10 -9 A/
It was mmHg. Reference Example An oxygen sensor was prepared in the same manner as in Example 1 except that an acetone solution of nitrocellulose was used instead of the PHEMA solution, and an experiment was conducted in the same manner as in Experimental Example 1 using this sensor. The results are shown in Figure 6.
The sensitivity was -1.35×10 -9 A/mmHg, about 10 times higher than conventional oxygen sensors. Example 3 As a conductive carbon material, the periphery of a pencil lead (made by mixing and sintering a thermoplastic resin with an aggregate such as pitch) (HB, diameter 0.5 mm) is insulated with epoxy resin, and the exposed tip surface is insulated with epoxy resin. It was polished with silicon carbide paper and washed with water. An oxygen sensor was fabricated by applying a methanol solution of PHEMA to the tip and drying it. Through a study using cyclic voltammetry, it was confirmed that an oxygen reduction wave appeared around -0.7V (vs. SSCE). Using this oxygen sensor, an experiment similar to Experimental Example 1 was conducted except that a voltage of -1.0 V (vs. SSCE) was applied. The relationship between the dissolved oxygen partial pressure and the reduction current value was a linear relationship as shown in FIG. Specific Effects of the Invention As described above, the present invention provides an oxygen sensor that can be manufactured using an inexpensive carbon material, has a fast response speed, and has good sensitivity. Since the adhesion between the carbon material and the polymer membrane is extremely good, this oxygen sensor has excellent durability. Further, it can be miniaturized to the processing limit of carbon materials.
第１図はこの発明に従う酸素センサーの断面
図、第２図は溶存酸素測定実験に用いる測定装置
図、第３図ないし第５図は、この発明の異なる実
施例の酸素センサーの特性を示すグラフ図、第６
図は、参考例の酸素センサーの特性を示すグラフ
図、第７図は、この発明のさらに別の実施例の酸
素センサーの特性を示すグラフ図。
１１…本体、１２…高分子膜。
FIG. 1 is a cross-sectional view of an oxygen sensor according to the present invention, FIG. 2 is a diagram of a measuring device used in a dissolved oxygen measurement experiment, and FIGS. 3 to 5 are graphs showing characteristics of oxygen sensors according to different embodiments of the present invention. Figure, 6th
FIG. 7 is a graph diagram showing the characteristics of an oxygen sensor according to a reference example, and FIG. 7 is a graph diagram showing characteristics of an oxygen sensor according to still another embodiment of the present invention. 11...Main body, 12...Polymer membrane.
Claims (1)
絶縁された、酸素と反応する電極部を有する酸素
濃度測定用微小センサーであつて、該電極部は、
単一の細長の柱状又は繊維状の導電性炭素材料か
らなり、該電極部の該露出先端面は、ポリ（メタ
クリル酸ヒドロキシエチル）からなる、酸素分子
及び水分子を透過させる高分子膜で覆われている
ことを特徴とする酸素濃度測定用微小センサー。 ２ 先端面の面積が、0.2mm2以下である特許請求
の範囲第１項記載の酸素濃度測定用微小センサ
ー。[Scope of Claims] 1. A microsensor for measuring oxygen concentration, which has an electrode portion that reacts with oxygen and has an exposed tip surface and is insulated on all sides other than the tip surface, the electrode portion comprising:
It is made of a single elongated columnar or fibrous conductive carbon material, and the exposed tip surface of the electrode part is covered with a polymer film made of poly(hydroxyethyl methacrylate) that allows oxygen molecules and water molecules to permeate. A micro sensor for measuring oxygen concentration. 2. The microsensor for measuring oxygen concentration according to claim 1, wherein the area of the tip surface is 0.2 mm 2 or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58152627A JPS6044859A (en) | 1983-08-22 | 1983-08-22 | Oxygen concentration measuring sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58152627A JPS6044859A (en) | 1983-08-22 | 1983-08-22 | Oxygen concentration measuring sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6044859A JPS6044859A (en) | 1985-03-11 |
| JPH0430544B2 true JPH0430544B2 (en) | 1992-05-22 |
Family
ID=15544513
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP58152627A Granted JPS6044859A (en) | 1983-08-22 | 1983-08-22 | Oxygen concentration measuring sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6044859A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6168030A (en) * | 1984-09-12 | 1986-04-08 | 東レ株式会社 | Minute sensor for measuring oxygen partial pressure |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57144453A (en) * | 1981-03-02 | 1982-09-07 | Hitachi Ltd | Polaro type electrode |
-
1983
- 1983-08-22 JP JP58152627A patent/JPS6044859A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57144453A (en) * | 1981-03-02 | 1982-09-07 | Hitachi Ltd | Polaro type electrode |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6044859A (en) | 1985-03-11 |
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