TW201816396A - Planar dissolved oxygen sensing electrode and manufacturing method thereof - Google Patents

Abstract

A planar dissolved oxygen sensing electrode and a manufacturing method thereof are provided for water quality monitoring. The structure includes an insulating base plate, an electric-conductive layer, an oxygen sensing layer, a reference sensing layer, and an electrolyte layer. The insulating base plate includes a planar surface. The electric-conductive layer is disposed on the planar surface of the insulating base plate. The electric-conductive layer includes a first conductive part, a second conductive part, a first reaction zone and a second reaction zone. The first conductive part and the second conductive part are insulated and apart from each other, and further connected to the first reaction zone and the second reaction zone, respectively. The oxygen sensing layer is disposed on the first reaction zone. The oxygen sensing layer includes plural catalyst particles and a polymer matrix, and the plural catalyst particles are dispersed in the polymer matrix. The reference sensing layer is disposed on the second reaction zone. The electrolyte layer is disposed on the oxygen sensing layer and the reference layer to cover thereon.

Description

Plane dissolved oxygen sensing electrode and manufacturing method thereof

This case relates to a sensing electrode used in water quality monitoring, especially a flat-type dissolved oxygen sensing electrode and its manufacturing method.

Sampling and analysis of traditional water quality monitoring often take a lot of time and manpower, and can not immediately and effectively reflect problems such as ineffective wastewater treatment or abnormal water quality, which in turn affects the quality of river water. In order to meet the actual needs, the water quality monitoring device must be able to analyze the water quality in real time, in order to effectively grasp the status of water treatment effectiveness and water quality changes, and then improve the operation of the treatment process. On the other hand, the demand for water recycling and reuse has also greatly increased the demand for water quality monitoring devices that can perform real-time online monitoring.

However, traditional water quality monitoring devices use glass electrodes as their ion sensing electrodes. Although the glass electrode can stably measure the ion concentration in water quality, its structure is complicated, the cost is expensive, and it is not conducive to miniaturization. In addition, the structure of the glass electrode and the reference electrode of the water quality monitoring device cannot effectively improve the sensitivity of the sensing. The electrode materials such as bulk precious metals (such as platinum, gold, and silver) used in traditional polarographic dissolved oxygen sensing electrodes are relatively expensive, and the sensitivity is poor due to the large amount of the electrode materials.

In view of the foregoing needs and problems, it is really necessary to provide a flat-type dissolved oxygen sensing electrode and a method for manufacturing the same, for application to water quality monitoring.

The purpose of this case is to provide a planar dissolved oxygen sensing electrode and a method for manufacturing the same. Through the planarization and the composite material of the catalyst particles and the polymer matrix, the sensing sensitivity of the dissolved oxygen sensing electrode is improved. The oxygen sensing layer uses a composite material of catalyst particles and a polymer matrix to improve the sensitivity of traditional polarographic dissolved oxygen measurement. The planar sensing layer structure reduces the volume of the overall sensing electrode and reduces the volume. The cost of making raw materials, so that the flat-type dissolved oxygen sensing electrode has high selectivity and sensitivity, and is used in medical, biochemical, chemical, agricultural, environmental and other fields, such as monitoring the change of dissolved oxygen concentration in the cultivation process of hydroponic plants , The amount of dissolved oxygen in the blood, the amount of dissolved oxygen in the eyeballs, the amount of dissolved oxygen in aquaculture, or the combination of specific enzymes to monitor specific biological indicators (such as glucose).

Another object of the present invention is to provide a planar dissolved oxygen sensing electrode and a manufacturing method thereof. Its small and compact structure, simple manufacturing process and low cost are more conducive to the purpose of providing disposable sensing electrodes.

To achieve the foregoing object, the present disclosure provides a planar dissolved oxygen sensing electrode, which includes an electrically insulating substrate, a conductive layer, an oxygen sensing layer, a reference sensing layer, and an electrolyte layer. The electrically insulating substrate has at least one plane. The conductive layer is disposed on at least one plane of the electrically insulating substrate. The conductive layer has a first conductive portion, a second conductive portion, a first reaction area, and a second reaction area. The first conductive portion and the second conductive portion are insulated from each other and are connected to the first reaction area and the second reaction area, respectively. . The oxygen sensing layer is disposed on the first reaction region connected to the first conductive portion. The oxygen sensing layer includes a plurality of catalyst particles and a polymer matrix, and the plurality of catalyst particles are dispersed in the polymer matrix. The reference sensing layer is disposed on the second reaction region. The electrolyte layer is disposed on and covers the oxygen sensing layer and the reference sensing layer.

In order to achieve the foregoing object, the present invention further provides a method for manufacturing a planar dissolved oxygen sensing electrode, comprising the steps of: (a) providing an electrically insulating substrate having at least one plane, and forming a conductive layer on at least one plane of the electrically insulating substrate, wherein The layer has a first conductive portion, a second conductive portion, a first reaction area, and a second reaction area. The first conductive portion and the second conductive portion are insulated from each other and are connected to the first reaction area and the second reaction area, respectively. b) forming an oxygen sensing layer and a reference sensing layer covering the first reaction zone and the second reaction zone, respectively, wherein the oxygen sensing layer includes a plurality of catalyst particles and a polymer matrix, and a plurality of catalysts The particles are dispersed in a polymer matrix; and (c) an electrolyte layer is formed to cover the oxygen sensing layer and the reference sensing layer.

Some typical embodiments embodying the features and advantages of this case will be described in detail in the description in the subsequent paragraphs. It should be understood that this case can have various changes in different aspects, all of which do not depart from the scope of this case, and that the descriptions and drawings therein are essentially for the purpose of illustration, rather than limiting the case.

This case discloses a planar dissolved oxygen (DO) sensing electrode 1 whose structure mainly includes an electrically insulating base plate, an electrically-conductive layer, and an oxygen-sensing layer. sensing layer), reference sensing layer, and electrolyte layer. In this case, the reference sensing layer may be, for example, but not limited to, a silver / silver chloride reference sensing layer. The conductive layer is disposed on the at least one plane of the electrically insulating substrate. The conductive layer has a first conductive portion, a second conductive portion, a first reaction region, and a second reaction region. The first conductive portion and the second conductive portion are insulated from each other. And connected to the first reaction zone and the second reaction zone, respectively. The oxygen sensing layer is disposed in the first reaction zone. The silver / silver chloride reference sensing layer is disposed in the second reaction zone. The electrolyte layer is disposed on and covers the oxygen sensing layer and the silver / silver chloride reference sensing layer. A planar oxygen sensing layer composed of a composite material of a plurality of catalyst particles and a polymer matrix is provided on the conductive layer by means of electrophoresis, electropolymerization, droplet coating or screen printing, and the accuracy can be achieved without losing accuracy. Then, the volume of the planar dissolved oxygen sensing electrode is greatly reduced, and the planar dissolved oxygen sensing electrode has high selectivity and sensitivity.

Please refer to FIG. 1, which is an exploded view showing the structure of a planar dissolved oxygen sensing electrode according to a preferred embodiment of the present invention. As shown in the figure, the planar dissolved oxygen sensing electrode (hereinafter referred to as the sensing electrode) 1 includes an electrically insulating substrate 10, a conductive layer 20, an insulating waterproof layer 30, an oxygen sensing layer 40, and a reference sensing layer 50. , A separator 60, an electrolyte layer 70, and a gas-permeable layer 80. The electrically insulating substrate 10 has at least one plane 11. The conductive layer 20 includes a first conductive portion 21 and a second conductive portion 22, which are respectively disposed on at least one plane 11 of the electrically insulating substrate 10 and are insulated from each other. In this embodiment, the first conductive portion 21 and the second conductive portion 22 are preferably disposed on the same plane 11. The first conductive portion 21 has a first reaction region 23. In this embodiment, since the reference sensing layer 50 used may be, for example, but not limited to, a silver / silver chloride reference sensing layer, corresponding to the reference sensing layer 50 composed of silver / silver chloride, the conductive layer 20 is more The conductive silver layer 24 is provided between the second conductive portion 22 and the electrically insulating substrate 10. The second conductive portion 22 of the conductive layer 20 partially covers the conductive silver layer 24, and the conductive silver layer 24 is not second conductive. A part of the assembly structure covered by the part 22 is the second reaction zone 25. The insulating and waterproof layer 30 is disposed on the conductive layer 20 and at least partially covers the first conductive portion 21 of the conductive layer 20 and covers the second conductive portion 22. The first conductive portion 21 is not covered by the insulating and waterproof layer 30, that is, the first reaction region 23 is assembled, and the second reaction region 25 of the conductive silver layer 24 is not covered or shielded by the insulating and waterproof layer 30. In this embodiment, the first reaction region 23 of the first conductive portion 21 and the second reaction region 25 of the conductive silver layer 24 are relatively adjacent to each other at a fine interval, which is beneficial to the miniaturization of the overall structure. More preferably, the first reaction region 23 and the second reaction region 24 are located at respective ends of the first conductive portion 21 and the conductive silver layer 24, respectively. The oxygen sensing layer 40 and the reference sensing layer 50 are respectively disposed in the first reaction region 23 of the first conductive portion 21 and the second reaction region 25 of the conductive silver layer 24. In other words, the insulating waterproof layer 30 and the oxygen sensing layer 40 cover the first conductive portion 21 together, and the reference sensing layer 50 covers the second reaction region 25 of the conductive silver layer 24. In an embodiment, the sensing electrode 1 further includes a solid chloride ion protection layer 51 disposed on the reference sensing layer 50 to maintain the surface chloride ion concentration of the reference sensing layer 50 at a fixed value. The chloride ion protective layer 50 is, for example, but not limited to, agarose, Polyacrylamide, Gelatin, Calcium alginate, or polyvinyl alcohol. Gel materials such as butyral resin (Polyvinyl butyral resin, PVB BUTVAR B-98,) are formed on the surface of the reference sensing layer 50 by removing a liquid electrolyte containing chloride ions. The liquid electrolyte may be, for example, but not limited to For potassium chloride, sodium chloride and hydrochloric acid. In a preferred embodiment, the solid chloride ion protective layer 51 is evenly mixed with a 3M potassium chloride aqueous solution and a 2% polyvinyl butyral resin (PVB, BUTVAR B-98) methanol aqueous solution. This gel layer was fixed to the surface of the reference electrode by a droplet coating method, and dried to form a film. It is worth noting that the insulating and waterproof layer 30, the oxygen sensing layer 40, and the reference sensing layer 50 can be formed on the same plane, for example, but not limited to, and the order of the composition can be adjusted according to actual needs. The order of the three. In a preferred embodiment, the first reaction region 23 and the second reaction region 25 are connected to the ends of the first conductive portion 21 and the second conductive portion 22, respectively, and the first conductive portion 21 and the second conductive portion 22 has a working electrode connection area 26 and a pair of electrode connection areas 27 at the other ends opposite to the first reaction area 23 and the second reaction area 25, respectively, and is exposed without being covered by the insulating waterproof layer 30, and is connected to the measurement A connection line (not shown) is formed to form a sensing circuit, but it does not limit the necessary technical features of this case, so it will not be repeated here. In addition, the electrolyte layer 70 is disposed on the oxygen sensing layer 40 and the reference sensing layer 50 and covers the oxygen sensing layer 40 and the reference sensing layer 50 at the same time. In this embodiment, the sensing electrode 1 further includes a septum 60 with an opening 61. The septum 60 is arranged around the oxygen sensing layer 40, the reference sensing layer 50, and the electrolyte layer 70, so as to make the electrolyte The layer 70 penetrates the opening 61 and is contained in the inner peripheral surface of the opening 61 and is in contact with the oxygen sensing layer 40 and the reference sensing layer 50. In addition, the sensing electrode 1 further includes a gas-permeable layer 80, which is disposed on the electrolyte layer 70 and is attached to the separator 60, so that the electrolyte layer 70 is maintained on the gas-permeable layer 80 and the ion-sensing layer 40 and the reference sensor. Between the sensing layers 50, the target sensing ions generated from the gas-permeable layer 80 are transmitted to the oxygen sensing layer 40 and the reference sensing layer 50 through the electrolyte layer 70, respectively. In a preferred embodiment, the electrolyte layer 70 is a 0.1 M tris (hydroxymethyl) aminomethane (Tris) aqueous solution. The fixed dispensing volume is set to 250 µL by a melter, and the septum is separated. After the electrolyte-filled area in the opening 61 of the sheet 60 is filled, the fabrication of the electrolyte layer 70 can be completed, thereby forming the sensing electrode 1 in this case.

In the foregoing embodiment, the oxygen sensing layer 40 is formed on the first reaction region 23 of the first conductive portion 21 of the conductive layer 20. FIG. 2 is a schematic diagram illustrating a cross-sectional structure of an oxygen sensing layer of a planar dissolved oxygen sensing electrode according to a preferred embodiment of the present invention. As shown in the figure, the oxygen sensing layer 40 is further composed of a plurality of catalyst particles 41 and a polymer matrix 42. The polymer matrix 42 may be, for example, but not limited to, polyaniline, polypyrrole ( Polypyrrole), a composite material of polyaniline and polypyrrole, Sulfonated tetrafluorethylene copolymer (Nafion), Chitosan, or Hydroxyethyl-cellulose. On the other hand, the catalyst particles 41 may be, for example, but not limited to, one selected from a single metal element M ₁ , a binary metal M ₁ -M ₂ , a ternary metal M ₁ -M ₂ -M ₃ , a single The metal oxide M ₁ O _X , a binary metal oxide M ₁ O _X -M ₂ O _X and a metal-metal oxide composite material M ₁ -M ₁ O _X are composed of at least one group. Among them, X is less than 3, and M ₁ , M ₂ and M ₃ may be respectively selected from platinum (Pt), gold (Au), palladium (Pd), silver (Ag), iridium (Ir), bismuth (Bi), Lithium (Li), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), aluminum (Al), chromium (Cr), titanium (Ti), manganese (Mn), antimony (Sb), Zinc (Zn), zirconium (Zr), gallium (Ga), molybdenum (Mo), ruthenium (Ru), rhodium (Rh), tin (Sn), indium (In), hafnium (Os), tantalum (Ta), One of the groups consisting of tungsten (W), cerium (Ce) and yttrium (Y). In one embodiment, the catalyst particles 41 include binary, ternary metals and binary metal oxides, and the molar ratio of the metal elements thereof is greater than 0 and less than 100%. In a preferred embodiment, the catalyst particles 41 are further composed of a plurality of Pt-Pd-Au ternary nano metal particles, and the average particle diameter of the catalyst particles 41 ranges from 0.5 nm to 100 μm. With the polymer substrate 42, the oxygen sensing layer 40 having the catalyst particles 41 and the polymer substrate 42 is formed on the first conductive portion 21 of the conductive layer 20 by means of electrophoresis, electropolymerization, droplet coating, and screen printing. Above the first reaction zone 23.

In this embodiment, the sensing electrode 1 can monitor the amount of dissolved oxygen in the aqueous solution by using a polarographic analysis method. Its sensing principle is to apply an applied potential between the cathode and anode, with a potential range between 1V and -1V. When the oxygen molecules reach the plane of the cathode, an electrochemical oxygen reduction reaction is performed (as shown in Formula 1), and the reference electrode of the anode is subjected to an electrochemical oxidation reaction (as shown in Formula 2). _{O 2 + H 2 O + 4e} - → 4OH - ( Formula ^{1) 4Cl - + 4Ag - 4e} - → 4AgCl ( Formula 2)

FIG. 3 is a diagram showing an exemplary electrochemical cyclic voltammetry result of one of the planar dissolved oxygen sensing electrodes in this case. The structure of the oxygen sensing layer 40 of the sensing electrode 1 is shown in FIG. An oxygen sensing layer 40 composed of Pt-Pd-Au ternary nanometer metal catalyst particles 41 and a polymer matrix 42 of a sulfonated tetrafluoroethyl copolymer (Nafion) is formed on the conductive layer 20 (refer to FIG. 1). (Refer to Figure 2). Figure 4 is a graph showing the results of electrochemical cyclic voltammetry of a traditional dissolved oxygen sensing electrode. The oxygen sensing layer of the sensing electrode is formed by sputtering a gold film (thickness 30 nm) on a screen-printed carbon conductive layer to form an oxygen sensor. Stratification. Comparing the results of Figure 3 and Figure 4, it can be seen that when sensing the dissolved oxygen content (0 ppm, 6 ppm, 20 ppm) in the aqueous solution under different atmospheres (nitrogen N ₂ , air Air, oxygen O ₂ ), the oxygen sensitivity of this case The measurement layer 40 has a special sensing structure composed of Pt-Pd-Au ternary nanometer metal catalyst particles 41 and a polymer matrix 42 of a sulfonated tetrafluoroethyl copolymer (Nafion). The applied potential of the method for oxygen reduction can be reduced to -0.2 V, representing that the oxygen sensing layer 40 has a high Pt-Pd-Au ternary nanometer metal catalyst particle 41 and a sulfonated tetrafluoroethyl copolymer (Nafion). The molecular matrix 42 catalyzes the reaction for oxygen reduction, reducing the bioenergy and the required driving force. In comparison, the oxygen-sensing layer made of a traditional gold-plated thin film has a poor ability to reduce oxygen at -0.2 V, so the sensitivity is not good.

On the other hand, Fig. 5 and Fig. 6 respectively show the current sensitivity sensing results under the conditions that the applied potentials of the electrochemical cyclic voltammeters of Figs. 3 and 4 are fixed at -0.2 V at the same time. Comparing Fig. 5 and Fig. 6, it can be seen that the present case is an oxygen sensing layer composed of Pt-Pd-Au ternary nano-metal catalyst particles 41 and a polymer matrix 42 of a sulfonated tetrafluoroethyl copolymer (Nafion). The oxygen reduction current signal obtained by 40 is nearly 100 times greater than the oxygen reduction current signal of the traditional oxygen sensing layer composed of a gold-plated thin film.

FIG. 7 is a comparison diagram of the sensitivity sensing results of the preferred implementation of the planar dissolved oxygen sensing electrode and the conventional sensing electrode. Similarly, the sensing electrode 1 of this case is touched by a metal contact of a ternary nanometer of Pt-Pd-Au. The media particles 41 and the polymer matrix 42 of the sulfonated tetrafluoroethyl copolymer (Nafion) constitute the oxygen sensing layer 40, while the conventional sensing electrodes are formed of a gold sputtered film (thickness 30 nm) to form the oxygen sensing layer. From the results shown in Figure 7 and Table 1 below, it can be seen that in this case, the metal catalyst particles 41 of the Pt-Pd-Au ternary nanometer and the polymer matrix 42 of sulfonated tetrafluoroethyl copolymer (Nafion) constitute oxygen The sensing oxygen sensitivity of sensing electrode 1 of sensing layer 40 is -2.39 µA / ppm, while the sensitivity of dissolved oxygen sensing of traditional gold-plated thin film sensing electrodes is -0.0059 µA / ppm. The planar dissolved oxygen sensing electrode 1 in this case can indeed effectively increase the sensitivity of sensing dissolved oxygen in an aqueous solution. Table 1: Comparison of the performance of the planar dissolved oxygen sensing electrode with the traditional gold-plated thin film sensing electrode.

It should be emphasized that the planarization of the sensing electrode 1 and the formation of the oxygen sensing layer 40 with the catalyst particles 41 and the polymer base layer 42 can effectively improve the sensing sensitivity and make the overall volume of the sensing electrode 1 Reduce and reduce the cost of making raw materials. The flat-type dissolved oxygen sensing electrode in this case has high selectivity and sensitivity, and can be applied to medical, biochemical, chemical, agricultural, environmental and other fields, such as monitoring the change of dissolved oxygen concentration in hydroponic plants, and dissolved oxygen in blood. Amount, dissolved oxygen in the eyeballs, dissolved oxygen in aquaculture, or combined with specific enzymes, specific biological indicators (such as glucose) can be monitored.

In addition, according to the planar dissolved oxygen sensing electrode structure of the foregoing preferred embodiment, the present invention also discloses a method for manufacturing a planar dissolved oxygen sensing electrode. FIG. 8 is a flowchart illustrating a method for manufacturing a planar dissolved oxygen sensing electrode according to a preferred embodiment of the present invention. Please refer to FIG. 1 and FIG. 8. First, in step S1, an electrically insulating substrate 10 is provided with at least one plane 11, and a conductive layer 20 is formed on at least one plane 11 of the electrically insulating substrate 10. The conductive layer 20 includes a first conductive portion 21 and a second conductive portion 22, which are respectively disposed on at least one plane 11 of the electrically insulating substrate 10 by means such as, but not limited to, screen printing or sputtering, and are insulated from each other. isolation. The first conductive portion 21 has a first reaction region 23. In this embodiment, before the first conductive portion 21 and the second conductive portion 22 of the conductive layer 20 are formed in step S1, a conductive silver layer is formed in advance using, for example, but not limited to, screen printing or sputtering techniques. 24, disposed between the second conductive portion 22 of the conductive layer 20 and the electrically insulating substrate 10, wherein the second conductive portion 22 of the conductive layer 20 partially covers the conductive silver layer 24 and is connected to the conductive silver layer 24, and is conductive The part of the silver layer 24 that is not covered by the second conductive portion 22 of the conductive layer 20 is a second reaction region 25, and the second reaction region 25 is connected to the second conductive portion 22 through the conductive silver layer 24. Therefore, in step S1, the first conductive portion 21, the second conductive portion 22, the first reaction region 23, and the second reaction region 25 are formed on the plane 11 of the electrically insulating substrate 10. Next, in step S2, an insulating and waterproof layer 30 is formed on the conductive layer 20, and the first conductive portion 21 of the conductive layer 20 is partially covered, so that the first conductive portion 21 is partially exposed and assembled into a first reaction region 23. At the same time, the insulating and waterproof layer 30 also covers the second conductive portion 22, but does not cover the second reaction region 25. In this embodiment, the insulating and waterproof layer 30 is covered on the conductive layer 20 by, for example, but not limited to, screen printing or chemical vapor deposition technology, so that the uncovered conductive layer 20 is partially assembled. The first reaction region 23 of the first conductive portion 21 is formed, and the second reaction region 25 of the conductive silver layer 24 is not covered. Among them, the first reaction region 23 of the first conductive portion 21 and the second reaction region 25 of the conductive silver layer 24 are relatively adjacent to each other at a fine interval, which is beneficial to the miniaturization of the overall structure. In a preferred embodiment, the first reaction region 23 and the second reaction region 25 are connected to the ends of the first conductive portion 21 and the second conductive portion 22, respectively, and the first conductive portion 21 and the second conductive portion 22 has a working electrode connection area 26 and a pair of electrode connection areas 27 at the other ends opposite to the first reaction area 23 and the second reaction area 25, respectively, and is exposed without being covered by the insulating waterproof layer 30, and is connected to the measurement A connection line (not shown) is formed to form a sensing circuit, but it does not limit the necessary technical features of this case, so it will not be repeated here. At the same time, in step S3, an oxygen sensing layer 40 and a reference sensing layer 50 are formed on the first reaction zone 23 and the second reaction zone 25, respectively. The reference sensing layer 50 may be, for example, but not limited to, a silver / silver chloride sensing layer. In this embodiment, the insulating waterproof layer 30, the oxygen sensing layer 40, and the reference sensing layer 50 collectively cover the conductive layer 20 and the conductive silver layer 24. Therefore, the insulating waterproof layer 30, the oxygen sensing layer 40, and the reference sensor The order in which the test layers 50 are formed on the conductive layer 20 is not limited, and can be optimized and adjusted according to actual application requirements, and details are not described herein again. Next, in step S4, an electrolyte layer 70 is formed to cover the oxygen sensing layer 40 and the reference sensing layer 50. In this embodiment, the electrolyte filling area is defined by the opening 61 of the septum 60, wherein the septum 60 is arranged around the oxygen sensing layer 40, the reference sensing layer 50, and the electrolyte layer 70, so as to make the electrolyte The layer 70 penetrates the opening 61 and is contained in the inner peripheral surface of the opening 61 and is in contact with the oxygen sensing layer 40 and the reference sensing layer 50. The separator 60 may be made of, for example, but not limited to, polyethylene terephthalate (PET). In addition, the electrolyte layer 70 may be, for example, but not limited to, an electrolyte filled region defined by filling an inner peripheral surface of the opening 61 of the separator 60 with a 1 M potassium chloride aqueous solution. Finally, in step S5, a gas-permeable layer 80 is formed on the electrolyte layer 70, and the gas-permeable layer 80 is adhered to the separator 60, so that the electrolyte layer 70 is held on the gas-permeable layer 80, the oxygen sensing layer 40, and the reference sensing layer 50. Even if the electrolyte layer 70 is contained in the electrolyte-filled area defined in the inner peripheral surface of the opening 61 of the septum 60. In this embodiment, the gas-permeable layer 80 may be, but is not limited to, a porous ceramic membrane.

In this embodiment, the material of the conductive silver layer 24 may be, for example, but not limited to, a screen printed conductive silver paste or a silver sputtered metal film, and the material of the electrically insulating substrate 10 may be, but not limited to, On polyethylene terephthalate (PET) or ceramic substrate. In one embodiment, in step S1, the conductive silver layer 24 may be printed on the electrically insulating substrate 10, and then placed at, for example, 60 ° C to 140 ° C and dried for 40 to 80 minutes. On the other hand, the conductive layer 20 may be, for example, but not limited to, a sputter-plated metal film, and its material may be selected from screen-printed silver-carbon conductive mixed paste, gold paste, platinum paste, silver paste, conductive carbon paste, gold, At least one of the groups consisting of palladium, platinum, gold-palladium alloy, and silver. In one embodiment, when the conductive layer 20 in step S1 can be printed on the electrically insulating substrate 10, the conductive silver layer 24 is partially covered, and the conductive silver layer 24 is partially exposed to form a second reaction region 25. For example, the conductive layer 20 and the conductive silver layer 24 can be formed on the electrically insulating substrate 10 by drying at 60 ° C. to 140 ° C. for 40 to 80 minutes.

In this embodiment, the first reaction region 23 of the first conductive portion 21 of the conductive layer 20 is covered by the oxygen sensing layer 40, and the second reaction region 25 of the conductive silver layer 24 is covered by the reference sensing layer 50. Then, the first reaction zone 23 and the second reaction zone 25 respectively form an oxygen reduction reaction and a silver oxidation reaction electrode region, which are used to transfer the electrochemical membrane potential generated by the oxygen sensing layer 40 and the reference sensing layer 50. And the electrical signal is transmitted to the measurement connection line through the first conductive portion 21 and the second conductive portion 22 of the conductive layer 20, respectively. In an embodiment, the measurement connection line is further connected to a measuring instrument (not shown), which can display and calculate the corresponding oxygen concentration of the sensing voltage change for subsequent users to use conveniently . In a preferred embodiment, the first reaction region 23 and the second reaction region 25 covered by the oxygen sensing layer 40 and the reference sensing layer 50 are insulated and isolated from each other, and are arranged adjacent to each other at a small distance to facilitate Miniaturization of the sensing electrode 1.

In addition, in this embodiment, the insulating and waterproof layer 30 may be made of, for example, but not limited to, materials having electrical insulation and water resistance, such as poly-para-xylylene, screen printing insulation glue, and screen printing UV insulation. A material such as glue is formed on the conductive layer 20. In one embodiment, the insulating and waterproof layer 30 is formed by coating a screen printing insulating glue and drying at 60 ° C. to 140 ° C. for 40 to 80 minutes. Because the insulating and waterproof layer 30 partially covers the conductive layer 20 and the uncovered portion of the first conductive portion 21 is configured as the first reaction region 23 and the second reaction region 25 that is not covered with the conductive silver layer 24, In the first reaction area 23 and the second reaction area 25, the insulating and waterproof layer 30 can be adjusted to cover a part of the conductive layer 20 to form a working electrode connection area 26 at the other ends of the first conductive portion 21 and the second conductive portion 22. The region 27 is connected to a pair of electrodes, and is connected to a measurement connection line (not shown) to form a sensing circuit, but this is not a limitation on the necessary technical features of this case, and is not repeated here.

In the embodiment of the present invention, the oxygen sensing layer 40 may be formed by, for example, but not limited to, electrophoresis, electropolymerization, droplet coating, and screen printing. Moreover, as shown in FIG. 2, the oxygen sensing layer 40 is further composed of a plurality of catalyst particles 41 and a polymer matrix 42. The polymer matrix 42 may be, for example, but not limited to, polyaniline, Polypyrrole, polyaniline and polypyrrole composites, Sulfonated tetrafluorethylene copolymer (Nafion), Chitosan, and Hydroxyethyl-cellulose. On the other hand, the catalyst particles 41 may be, for example, but not limited to, one selected from a single metal element M ₁ , a binary metal M ₁ -M ₂ , a ternary metal M ₁ -M ₂ -M ₃ , a single The metal oxide M ₁ O _X , a binary metal oxide M ₁ O _X -M ₂ O _X and a metal-metal oxide composite material M ₁ -M ₁ O _X are composed of at least one group. Among them, X is less than 3, and M ₁ , M ₂ and M _{3 can be} selected from platinum (Pt), gold (Au), palladium (Pd), silver (Ag), iridium (Ir), bismuth (Bi), lithium (Li), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), aluminum (Al), chromium (Cr), titanium (Ti), manganese (Mn), antimony (Sb), zinc (Zn), zirconium (Zr), gallium (Ga), molybdenum (Mo), ruthenium (Ru), rhodium (Rh), tin (Sn), indium (In), hafnium (Os), tantalum (Ta), tungsten (W), cerium (Ce), and yttrium (Y). In one embodiment, the catalyst particles 41 include binary, ternary metals and binary metal oxides, and the molar ratio of the metal elements thereof is greater than 0 and less than 100%. In a preferred embodiment, the catalyst particles 41 are further composed of a plurality of Pt-Pd-Au ternary nano metal particles, and the average particle diameter of the catalyst particles 41 ranges from 0.5 nanometers to 100 micrometers. Between the polymer substrate 42 and the polymer substrate 42, the oxygen sensing layer 40 having the catalyst particles 41 and the polymer substrate 42 is formed in the first conductive portion of the conductive layer 20 by means of electrophoresis, electropolymerization, droplet coating or screen printing. 21 的 第一 反应 区 23。 21 above the first reaction zone 23. In a preferred embodiment, a sulfonated tetrafluoroethyl copolymer (Nafion) is selected as the polymer matrix 42 and mixed with deionized water to form an aqueous solution of the polymer matrix 42 at a concentration ranging from 0.1 wt% to 2 wt %between. On the other hand, the catalyst particles 41 are composed of a plurality of Pt-Pd-Au ternary nanometer metal catalyst particles, and the average particle diameter of the catalyst particles 41 ranges from 0.5 nanometers to 100 micrometers. The 42 aqueous solution has a mixed concentration range of 0.01 mg / mL to 2 mg / mL. The suspended slurry of the mixed catalyst particles 41 and the polymer matrix 42 is dispersed in an aqueous solution of the polymer matrix 42 with a ultrasonic oscillator under an ice bath at 4 ° C. and then used for backup. Finally, the suspension slurry of the catalyst particles 41 and the polymer matrix 42 is dripped on the first reaction zone 23 by a droplet coating method, and the volume of the droplets is 20 μL to 60 μL, and dried at, for example, 30 ° C. to 60 ° C. After 2 to 10 hours, vacuum drying at, for example, 40 ° C. to 60 ° C. for 6 to 18 hours can complete the production of the oxygen sensing layer 40.

In addition, the reference sensing layer 50 in the embodiment of the present case can be formed by the second reaction of the conductive silver layer 24 through, for example, but not limited to, a droplet coating method, a sputtering method, an electrodeposition method, or a screen printing thick film technology. On the 25th. The material of the reference sensing layer 50 may be, for example, but not limited to, silver silver chloride (Ag / AgCl), mercury / mercury chloride, or other metal oxides, such as iridium oxide (IrO ₂ ), ruthenium oxide (RuO ₂ ), platinum oxide (PtO _X ), palladium oxide (PdO _X ), tin oxide (SnO ₂ ), tantalum oxide (Ta ₂ O ₅ ), rhodium oxide (RhO ₂ ), hafnium oxide (OsO ₂ ), titanium oxide ( TiO ₂ ), mercury oxide (Hg ₂ O) or antimony oxide (Sb ₂ O ₃ ). In one embodiment, the reference sensing layer 50 is made of silver / silver chloride (Ag / AgCl), and can be fabricated by, for example, but not limited to, an electrochemical constant voltage method. The applied voltage ranges from 0.6 V to 1.0. Between V, the oxidation time is 60 seconds to 180 seconds, and the reference sensing layer 50 obtained after the oxidation can be washed with deionized water, and placed in an environment of 80 ℃, dried for 1 hour, and the excess moisture can be dried. The reference electrode 50 of silver silver chloride (Ag / AgCl) is completed. The electro-oxidation treatment liquid may be, for example, but not limited to, an aqueous potassium chloride solution, and the concentration ranges from 0.1 M to 3 M, but this is not a limitation on the necessary technical features of the present case, and is not repeated here.

In one embodiment, the sensing electrode 1 further includes a protective layer, such as, but not limited to, a solid chloride ion protective layer 51 disposed on the reference sensing layer 50. The solid chloride ion protective layer 51 is composed of a gel material and a liquid electrolyte containing chloride ions. After the liquid electrolyte is attached to the gel material, it passes through, for example, but is not limited to, a droplet coating method, a mesh, and the like. The thick film technology is formed on the surface of the reference sensing layer 50. The gel material in the solid chloride ion protective layer 51 may be, for example, but not limited to, agarose gel, polyacrylamide gelatin, gelatin, and calcium alginate. Or polyvinyl butyral resin (Polyvinyl butyral resin, PVB, BUTVAR B-98) and other gel materials. The liquid electrolyte in the solid chloride ion protection layer 51 may be, for example, but not limited to, an aqueous solution of hydrochloric acid, an aqueous solution of potassium chloride, and an aqueous solution of sodium chloride, and the concentration ranges between 0.5 M and 3 M. The liquid electrolyte containing chloride ions is attached to the gel material and is formed on the surface of the reference sensing layer 50. The concentration of the liquid electrolyte is in a range of 0.5 wt.% To 5 wt.%. In a preferred embodiment, a 3M sodium chloride aqueous solution and a 2 wt% polyvinyl butyral resin (Polyvinyl butyral resin (PVB, BUTVAR B-98)) methanol solution are evenly mixed, and then applied through droplets. The solid chloride ion protection layer 51 is fixed on the surface of the reference sensing layer 50 by placing the solid chloride ion protection layer 51 on the surface of the reference sensing layer 50 under an environment of 60 ° C. for one hour. Making.

In the foregoing embodiment, the septum 60 is circumferentially arranged around the oxygen sensing layer 40 and the reference sensing layer 50. The inner peripheral surface of the opening 61 of the septum 60 is more specifically defined as an electrolyte filling area to fill Electrolyte layer 70. In one embodiment, the separator 60 may be, for example, but not limited to, a material such as polyethylene terephthalate (PET) or polyvinyl chloride (PVC). In a preferred embodiment, the separator 60 is made of polyethylene terephthalate (PET) and has a thickness of 0.35 mm. A back adhesive is applied to the back surface of the separator 60 to attach it to the electrically insulating substrate 10. The plane 11 is arranged on the periphery of the oxygen sensing layer 40 and the reference sensing layer 50, and then it is pressed and placed for 12 hours by a rolling machine to make the adhesion area stronger, and within the opening 61 of the septum 60 The combination is defined within the peripheral surface to define an electrolyte filling area for filling the electrolyte layer 70.

In the foregoing embodiment, the material of the electrolyte layer 70 is a liquid electrolyte, and may be, for example, but not limited to, an aqueous solution of hydrochloric acid, an aqueous solution of potassium chloride, an aqueous solution of potassium hydroxide, an aqueous solution of sodium chloride, an aqueous solution of phosphate buffer, and Tris (hydroxymethyl) aminomethane (Tris) aqueous solution, perchloric acid solution or sulfuric acid solution, the concentration range is from 0.01 M to 1 M. In a preferred embodiment, a 0.1 M aqueous solution of tris (hydroxymethyl) aminomethane (Tris) is used to set the fixed dispensing volume to 250 µL through a dispenser, and the septum 60 After the electrolyte-filled area in the opening 61 is filled, the fabrication of the electrolyte layer 70 can be completed.

In addition, the material of the gas permeable layer 80 in the foregoing embodiment may be, for example, but not limited to, cellulose acetate, silicone rubber, polytetrafluoroethylene (PTFE), fluorinated ethylene propylene copolymer (FEP), and polydimethylsiloxane. It is composed of oxane (PDMS), polyvinyl chloride (PVC), natural rubber or a combination thereof. In this embodiment, the thickness of the gas-permeable layer 80 may be between 0.1 μm and 30 μm. In a preferred embodiment, the gas-permeable layer 80 is made of a polytetrafluoroethylene film with a thickness of 10 μm, the back surface is coated with adhesive, and the polytetrafluoroethylene film is pasted on the bonding jig. Above the separator 60 and covering the electrolyte layer 70, the electrolyte layer 70 is encapsulated in the opening 61 of the separator 60 to constitute the sensing electrode 1 of the present case. In addition, the material of the gas permeable layer 80 may also be composed of, but not limited to, silicate minerals, aluminosilicate minerals, diatomaceous earth, silicon carbide, silicon carbide, silicon dioxide, metal oxides, or combinations thereof. The porous ceramic film prepared by calcination is used as the structure of the gas-permeable layer 80. In a preferred embodiment, after the gas permeable layer 80 is calcined from silicon carbide, an O-ring (not shown) is used to fix the periphery of the gas permeable layer 80, and at the same time, it is fixed to a septum. The electrolyte-filled area defined by the inner peripheral surface of the opening 61 of 60 is sealed with epoxy resin to achieve the effect of preventing water leakage, but this is not a feature that limits the necessary technology in this case, and is not repeated here.

In summary, the present invention provides a planar dissolved oxygen sensing electrode and a manufacturing method thereof. Through the planarization and the catalyst particles and the polymer matrix, the sensing sensitivity of the dissolved oxygen sensing electrode is improved. Among them, the oxygen sensing layer uses a composite material of catalyst particles and a polymer matrix to improve the sensitivity of traditional polarographic measurement of dissolved oxygen. The planar sensing layer structure reduces the volume of the overall sensing electrode and reduces the cost of raw materials. In order to make the flat-type dissolved oxygen sensing electrode have high selectivity and sensitivity, it is used in medical, biochemical, chemical, agricultural, environmental and other fields, such as monitoring the change of dissolved oxygen concentration in the cultivation process of hydroponic plants, and the solubility in blood. The amount of oxygen, the amount of dissolved oxygen in the eyeballs, the amount of dissolved oxygen in aquaculture water, or the combination of specific enzymes can be used to monitor specific biological indicators (such as glucose). And its structure is compact and simple, and the cost is low, which is more conducive to the purpose of providing disposable sensing electrodes.

1‧‧‧planar dissolved oxygen sensing electrode (referred to as sensing electrode)

10‧‧‧electrically insulated substrate

11‧‧‧plane

20‧‧‧ conductive layer

21‧‧‧The first conductive part

22‧‧‧Second conductive section

23‧‧‧First reaction zone

24‧‧‧ conductive silver layer

25‧‧‧Second reaction zone

26‧‧‧Working electrode connection area

27‧‧‧ counter electrode connection area

30‧‧‧Insulation waterproof layer

40‧‧‧ oxygen sensing layer

41‧‧‧catalyst particles

42‧‧‧ polymer matrix

50‧‧‧Reference sensing layer

51‧‧‧Solid chloride ion protective layer

60‧‧‧ Septa

61‧‧‧ opening

70‧‧‧ electrolyte layer

80‧‧‧Gas breathable layer

Steps S1 ~ S5‧‧‧‧

FIG. 1 is an exploded view showing the structure of a planar dissolved oxygen sensing electrode according to a preferred embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating a cross-sectional structure of an oxygen sensing layer of a planar dissolved oxygen sensing electrode according to a preferred embodiment of the present invention.

FIG. 3 is a graph showing an exemplary electrochemical cyclic voltammetry result of one of the planar dissolved oxygen sensing electrode electrodes of the present case.

Figure 4 is a graph showing the results of electrochemical cyclic voltammetry of a traditional dissolved oxygen sensing electrode.

Figures 5 and 6 show the results of current sensitivity sensing under the conditions where the applied potentials of the electrochemical cyclic voltammeters of Figures 3 and 4 are fixed at -0.2 V, respectively.

FIG. 7 is a comparison diagram of the sensitivity sensing results of the flat-type dissolved oxygen sensing electrode and the conventional sensing electrode in the preferred embodiment of the present invention.

FIG. 8 is a flowchart illustrating a method for manufacturing a planar dissolved oxygen sensing electrode according to a preferred embodiment of the present invention.

Claims (17)

A planar dissolved oxygen sensing electrode includes: an electrically insulating substrate having at least one plane; a conductive layer disposed on the at least one plane of the electrically insulating substrate, wherein the conductive layer has a first conductive portion, a A second conductive portion, a first reaction area and a second reaction area, the first conductive portion and the second conductive portion are insulated from each other, and are connected to the first reaction area and the second reaction area, respectively; an oxygen A sensing layer is disposed above the first reaction zone, wherein the oxygen sensing layer includes a plurality of catalyst particles and a polymer matrix, and the plurality of catalyst particles are dispersed in the polymer matrix; a reference A sensing layer is disposed on the second reaction zone; and an electrolyte layer is disposed on and covers the oxygen sensing layer and the reference sensing layer. The planar dissolved oxygen sensing electrode according to claim 1, wherein the catalyst particles are selected from a single metal element M ₁ , a binary metal M ₁ -M ₂ , and a ternary metal M ₁ -M ₂ -M ₃ , a single metal oxide M ₁ O _X , a binary metal oxide M ₁ O _X -M ₂ O _X, and a metal-metal oxide composite M ₁ -M ₁ O _X Consisting of at least one of which 0 <X <3, M ₁ , M ₂ and M ₃ are selected from platinum, gold, palladium, silver, iridium, bismuth, lithium, iron, cobalt, nickel, copper, aluminum, chromium, One of the groups consisting of titanium, manganese, antimony, zinc, zirconium, gallium, molybdenum, ruthenium, osmium, tin, indium, osmium, tantalum, tungsten, cerium and yttrium. The planar dissolved oxygen sensing electrode according to claim 1, wherein the average particle diameter of the catalyst particles ranges from 0.5 nm to 100 μm. The planar dissolved oxygen sensing electrode according to claim 1, wherein the polymer-based system is selected from the group consisting of polyaniline, polypyrrole, polyaniline and polypyrrole composite material, sulfonated tetrafluoroethyl copolymer, chitin, and hydroxyl At least one of the group consisting of ethyl cellulose. The planar dissolved oxygen sensing electrode according to claim 1, wherein the conductive layer further includes a conductive silver layer disposed between the electrically insulating substrate and the second conductive portion, and partially exposed to the second conductive portion. Outside the conductive part, an assembly structure is used as the second reaction area, wherein the reference electrode layer is selected from the group consisting of silver, silver chloride, mercury, mercury chloride, iridium oxide, ruthenium oxide, platinum oxide, palladium oxide, and tin oxide. Consisting of tantalum oxide, rhodium oxide, hafnium oxide, titanium oxide, mercury oxide, and antimony oxide, wherein the planar dissolved oxygen sensing electrode further includes a protective layer disposed on the reference sensor. Overlay. The planar dissolved oxygen sensing electrode according to claim 1, further comprising an insulating and waterproof layer disposed on the conductive layer, covering the second conductive portion, and partially covering the first conductive portion, so that the first A part of the conductive frame exposed to the outside of the insulating and waterproof layer constitutes the first reaction area. The planar dissolved oxygen sensing electrode according to claim 1, further comprising a spacer disposed on the at least one plane of the electrically insulating substrate, wherein the spacer has an opening, and the spacer is disposed on The periphery of the oxygen sensing layer and the reference sensing layer, and the electrolyte layer is contained in the inner peripheral surface of the opening. The planar dissolved oxygen sensing electrode according to claim 7, further comprising a gas permeable layer, which is disposed and covered on the electrolyte layer, and is attached to the separator, so that the electrolyte layer is kept in the gas. Between the gas-permeable layer and the oxygen sensing layer and the reference sensing layer. A method for manufacturing a planar dissolved oxygen sensing electrode includes the steps of: (a) providing an electrically insulating substrate having at least one plane, and forming a conductive layer on the at least one plane of the electrically insulating substrate, wherein the conductive layer has a A first conductive portion, a second conductive portion, a first reaction area and a second reaction area, the first conductive portion and the second conductive portion are insulated from each other, and are respectively connected to the first reaction area and the first Two reaction zones; (b) forming an oxygen sensing layer and a reference sensing layer respectively covering the first reaction zone and the second reaction zone, wherein the oxygen sensing layer includes a plurality of catalyst particles and a high A molecular matrix, and the plurality of catalyst particles are dispersed in the polymer matrix; and (c) forming an electrolyte layer covering the oxygen sensing layer and the reference sensing layer. The method for manufacturing a planar dissolved oxygen sensing electrode according to claim 9, wherein the catalyst particles are selected from a single metal element M ₁ , a binary metal M ₁ -M ₂ , and a ternary metal M _1- M ₂ -M ₃ , a single metal oxide M ₁ O _X , a binary metal oxide M ₁ O _X -M ₂ O _X, and a metal-metal oxide composite M ₁ -M ₁ O _X Consisting of at least one of the groups, where 0 <X <3, M ₁ , M ₂ and M ₃ are selected from platinum, gold, palladium, silver, iridium, bismuth, lithium, iron, cobalt, nickel, copper, aluminum, One of the groups consisting of chromium, titanium, manganese, antimony, zinc, zirconium, gallium, molybdenum, ruthenium, rhenium, tin, indium, rhenium, tantalum, tungsten, cerium and yttrium. The method for manufacturing a planar dissolved oxygen sensing electrode according to claim 9, wherein the average particle diameter of the catalyst particles ranges from 0.5 nm to 100 μm. The method for manufacturing a planar dissolved oxygen sensing electrode according to claim 9, wherein the polymer-based system is selected from the group consisting of polyaniline, polypyrrole, polyaniline and polypyrrole composite material, sulfonated tetrafluoroethyl copolymer, and chitin And at least one of the group consisting of hydroxyethyl cellulose. The method for manufacturing a planar dissolved oxygen sensing electrode according to claim 9, wherein the step (a) further includes a step (a1) forming a conductive silver layer, which is disposed on the electrical edge insulation substrate and the second conductive portion. And is partially exposed outside the second conductive part, and an assembly structure is used as the second reaction area, wherein the reference electrode layer is selected from the group consisting of silver, silver chloride, mercury, mercury chloride, iridium oxide, and oxide Ruthenium, platinum oxide, palladium oxide, tin oxide, tantalum oxide, rhodium oxide, hafnium oxide, titanium oxide, mercury oxide, and antimony oxide are composed of at least one of the groups, wherein the planar dissolved oxygen sensing electrode, more It includes a protective layer disposed on the reference sensing layer. The method for manufacturing a planar dissolved oxygen sensing electrode according to claim 9, wherein in the step (b), the plurality of catalyst particles of the oxygen sensing layer and the polymer-based system use electrophoresis, electropolymerization, and droplets. A coating or screen printing method is formed on the first reaction zone. The method for manufacturing a planar dissolved oxygen sensing electrode according to claim 9, wherein step (b) further includes step (b1) forming an insulating and waterproof layer on the conductive layer to cover the second conductive portion, and the portion The first conductive portion is partially covered, so that a portion of the assembly that exposes the first conductive portion to the outside of the insulating and waterproof layer constitutes the first reaction area. The method for manufacturing a planar dissolved oxygen sensing electrode according to claim 9, wherein step (c) further includes step (c1) providing a spacer with an opening, and bonding the spacer to the electrical insulation The at least one plane of the substrate is such that the septum is disposed on the periphery of the oxygen sensing layer and the reference sensing layer, and the electrolyte layer is contained in the inner peripheral surface of the opening. The method for manufacturing a planar dissolved oxygen sensing electrode as described in claim 16, further comprising a step (d) forming a gas-permeable layer on the electrolyte layer, and bonding the gas-permeable layer to the separator to maintain the electrolyte layer. Within the inner peripheral surface of the opening of the septum.