TWI625522B - Planar ammonia selective sensing electrode and manufacturing method thereof - Google Patents

Abstract

This case relates to a planar ammonia-selective sensor and its manufacturing method for water quality monitoring. The structure includes an electrically insulating substrate, a conductive layer, an ammonium ion sensing layer, a hydroxide ion 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 at least a first conductive portion and at least a second conductive portion. The first conductive portion and the second conductive portion are insulated from each other, and are respectively provided with a first reaction region and a second reaction region. The ammonium ion sensing layer is disposed in the first reaction area of the first conductive portion. The hydroxide ion sensing layer is disposed in the second reaction area of the second conductive portion. The electrolyte layer is disposed on and covers the ammonium ion sensing layer and the hydroxide ion sensing layer.

Description

Planar ammonia-selective sensing electrode and manufacturing method thereof

This case relates to a sensing electrode used for water quality monitoring, and in particular, a planar ammonia-selective 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.

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

The purpose of this case is to provide a planar ammonia-selective sensing electrode and a manufacturing method thereof. Planarly set the ammonium ion sensing layer and hydroxide ion sensing layer on a conductive layer by droplet coating method, sputtering method, electrodeposition method or screen printing thick film technology to improve accuracy, and Significantly reduces the volume of the sensing electrode. At the same time, the flat-type ammonia-selective sensing electrode has high selectivity and sensitivity for applications in medicine, biochemistry, chemistry, agriculture, environment, and other fields, such as monitoring the changes in the concentration of ammonia nitrogen in the cultivation of hydroponic plants and the concentration of ammonia nitrogen in human sweat Changes, aquaculture water quality monitoring, or specific enzymes can be combined to detect specific biological indicators (such as creatine peptone).

Another object of this case is to provide a planar ammonia-selective 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 invention provides a planar ammonia-selective sensing electrode, including an electrically insulating substrate, a conductive layer, an ammonium ion sensing layer, a hydroxide ion 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 at least a first conductive portion and at least a second conductive portion. The first conductive portion and the second conductive portion are insulated from each other, and are respectively provided with a first reaction region and a second reaction region. The ammonium ion sensing layer is disposed in the first reaction area of the first conductive portion. The hydroxide ion sensing layer is disposed in the second reaction area of the second conductive portion. The electrolyte layer is disposed on and covers the ammonium ion sensing layer and the hydroxide ion sensing layer.

In order to achieve the foregoing object, the present invention further provides a method for manufacturing a planar ammonia-selective 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, The conductive layer has at least a first conductive portion and at least a second conductive portion, the first conductive portion and the second conductive portion are insulated from each other, and are respectively provided with a first reaction region and a second reaction region; (b) Forming an ammonium ion sensing layer and a hydroxide ion sensing layer to cover the first reaction region of the first conductive portion and the second reaction region of the second conductive portion, respectively; and (c) forming an electrolyte layer to cover the On the ammonium ion sensing layer and the hydroxide ion 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 ammonia selective sensing electrode, whose structure mainly includes an insulating base plate, an electrically-conductive layer, and an ammonium ion sensing layer. ), A hydroxide ion sensing layer (hydroxide ion sensing layer), and an electrolyte layer (electrolyte layer). In the present case, the hydroxide ion sensing layer may be, for example, but not limited to, a pH sensing layer or a pH sensing layer. The conductive layer is disposed on the plane of the electrically insulating substrate. The conductive layer has at least a first conductive portion and at least a second conductive portion. The first conductive portion and the second conductive portion are insulated from each other, and are respectively provided with a first reaction. Zone and a second reaction zone. The ammonium ion sensing layer is disposed in the first reaction area of the first conductive portion. The hydroxide ion sensing layer is disposed in the second reaction area of the second conductive portion. The electrolyte layer is disposed on and covers the ammonium ion sensing layer and the hydroxide ion sensing layer. The droplet type coating method, the sputtering method, the electrodeposition method or the screen printing thick film technology are used to set the planar ammonium ion sensing layer and the planar hydroxide ion sensing layer on the conductive layer, and the In the case of accuracy, the volume of the planar ammonia-selective sensing electrode is greatly reduced, and the planar ammonia-selective sensing electrode has high selectivity and sensitivity.

Please refer to FIG. 1, which is an exploded view showing the structure of a planar ammonia-selective sensing electrode according to a preferred embodiment of the present invention. As shown in the figure, the planar ammonia selective sensing electrode (hereinafter referred to as the sensing electrode) 1 in this case includes an electrically insulating substrate 10, a conductive layer 20, an insulating waterproof layer 30, an ammonium ion sensing layer 40, and a pH 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 and the second conductive portion 22 have a first reaction region 23 and a second reaction region 24, respectively. The insulating and waterproof layer 30 is disposed on the conductive layer 20, at least partially covers the first conductive portion 21 and the second conductive portion 22 of the conductive layer 20, and partially exposes the first conductive portion 21 and the second conductive portion 22, respectively. The portions of the first conductive portion 21 and the second conductive portion 22 that are exposed outside the insulating and waterproof layer 30 are respectively configured as the first reaction region 23 and the second reaction region 24. Preferably, the first reaction region 23 and the second reaction region 24 of the first conductive portion 21 and the second conductive portion 22 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 second conductive portion 22, respectively. The ammonium ion sensing layer 40 and the pH sensing layer 50 are respectively disposed on the exposed portions of the first conductive portion 21 and the second conductive portion 22 that are not covered by the insulating and waterproof layer 30, that is, correspondingly provided on the first reaction area 23 and第二 反应 区 24。 The second reaction zone 24. In other words, the insulating waterproof layer 30, the ammonium ion sensing layer 40, and the pH sensing layer 50 collectively cover the conductive layer 20. The insulating waterproof layer 30, the ammonium ion sensing layer 40, and the pH sensing layer 50 may be, but not Limited to coplanar settings. In a preferred embodiment, except that the first reaction region 23 and the second reaction region 24 are located at respective ends of the first conductive portion 21 and the second conductive portion 22, respectively, the first conductive portion 21 and the second conductive portion 22 has a working electrode connection area 25 and a pair of electrode connection areas 26 at the other ends opposite to the first reaction area 23 and the second reaction area 24, respectively, and is exposed without being covered by the insulating waterproof layer 30, and is connected to the measurement Connect a line (not shown) to form a sensing circuit. In addition, the electrolyte layer 70 is disposed on the ammonium ion sensing layer 40 and the pH sensing layer 50 and covers the ammonium ion sensing layer 40 and the pH sensing layer 50 at the same time. In this embodiment, the sensing electrode 1 further includes a septum 60 with an opening 61, and the septum 60 is arranged around the ammonium ion sensing layer 40, the pH 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 ammonium ion sensing layer 40 and the pH 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 ammonium ion sensing layer 40 and pH. Between the sensing layers 50, the target sensing ions generated from the gas-permeable layer 80 are transmitted to the ammonium ion sensing layer 40 and the pH sensing layer 50 through the electrolyte layer 70, respectively.

In the present embodiment, the target sensing ion ammonium ion sensing layer 40 and the pH sensing layer 50 are an ammonium ion (NH ₄ ⁺⁾ and hydroxide ions (OH ^-). Since ammonia is dissolved in water, ammonium ions (NH ₄ ⁺ ) and hydroxide ions (OH ⁻ ) are generated. The chemical reaction formula is shown in (Formula 1). Aqueous ammonia molecules in the specimen through the gas permeable layer 80 is diffused to the ammonium ion (NH ₄ ⁺⁾ and hydroxide ions (OH ^-) in the electrolyte to a concentration of the electrolyte layer 70 changes, and then were transferred to the ammonium ion sensing layer 40 and pH sensing layer 50. The ammonium ion (NH ₄ ⁺ ) will react with the ammonium ion reaction layer 40 to generate a change in the electrochemical membrane voltage. When the concentration of the ammonium ion in the aqueous solution is higher, the membrane voltage generated at the ammonium ion reaction layer 40 is greater. On the other hand, since the ions will generate hydroxide (OH ^-) is dissolved in aqueous ammonia resulting alkaline aqueous solution was changed at this time pH sensing layer 50 is sensed by a hydroxide ion (OH ^-) voltage is in the form Negative growth. In other words, as the aqueous solution itself becomes more alkaline, the voltage of the hydroxide ions (OH ⁻ ) sensed by the pH sensing layer 50 is smaller. Therefore, when ammonia is present in the aqueous solution, the signals sensed by the ammonium ion sensing layer 40 and the pH sensing layer 50 will have an additive effect, so the sensing electrode 1 proposed by the present invention can greatly improve the traditional electrochemical Sensitivity to measure ammonia concentration. NH ₃ + H ₂ O ⇌ NH ₃ · H ₂ O⇌NH ₄ ⁺ + OH ⁻ (Equation 1)

FIG. 2 is a voltage sensing curve showing an exemplary sensing voltage of one of the planar ammonia-selective sensing electrodes of the present case. FIG. 3 is a calibration curve illustrating the relationship between the voltage of the sensing data and the ammonia concentration of the planar ammonia-selective sensing electrode and the conventional ammonia sensing electrode in the preferred embodiment of the present invention. As shown in the figure, when the ammonia / ammonium concentration in the aqueous solution is increased, the traditional method of measuring the membrane potential is only relative to the reference electrode silver / silver chloride, that is, the ammonia / ammonium concentration sensing voltage E _{NH4 +} = E _{Working (NH4 +)} -E _Reference . When the ammonia / ammonium concentration is higher, the ammonia / ammonium concentration sensing voltage E _{NH4 +} relative to the reference electrode silver / silver chloride will be higher, but the change can only conform to the slope change of the electrochemical energy equation 59.2 ± 2 mV / (10 times). However, in this embodiment, since the change of the pH value in the aqueous solution is also calculated at the same time, that is, the pH sensing voltage E _pH = E _{Working (pH)} -E _Reference relative to the reference electrode silver / silver chloride, when When the aqueous solution is affected by the dissolution of ammonia, a reaction occurs as shown in Equation 1, which causes the pH of the aqueous solution to increase, that is, the lower the pH sensing voltage E _pH . Therefore, in this embodiment, the measuring method of the sensing electrode 1 is to use the difference between the ammonia / ammonium concentration sensing voltage E _{NH4 +} and the pH sensing voltage E _pH , that is, E _{NH4 +} -E _pH = E _{Working (NH4 +)} -E _{Working (pH)} makes the sensitivity slope of the flat-type ammonia-selective sensing electrode 1 in this case change to 132 ± 3 mV / (10 times), which is 59.2 ± 2 mV / (10-fold) than the sensitivity of the conventional ammonia sensing electrode Much higher, as shown in Figure 3 and Table 1 below. Table 1: A comparison table of the performance of the planar ammonia-selective sensing electrode and the traditional ammonia sensing electrode of the preferred embodiment of the present case. <TABLE border = "1" borderColor = "# 000000" width = "85%"><TBODY><tr><td></td><td> In this case, the flat type ammonia selection sensor </ td><td> Traditional ammonia sensing electrode </ td></tr><tr><td> Linear range </ td><td> 0.01 – 1400 ppm </ td><td> 0.01 – 1400 ppm </ td>< / tr><tr><td> Linearity </ td><td> R <sup> 2 </ sup> = 0.9901 </ td><td> R <sup> 2 </ sup> = 0.9954 </ td ></tr><tr><td> Sensitivity </ td><td> 132 mV / 10 multiples </ td><td> 59.2 mV / 10 multiples </ td></tr></TBODY></ td TABLE>

On the other hand, according to the planar ammonia-selective sensing electrode structure of the aforementioned preferred embodiment, this case also discloses a method for manufacturing a planar ammonia-selective sensing electrode. FIG. 4 is a flowchart illustrating a method for manufacturing a planar ammonia-selective sensing electrode according to a preferred embodiment of the present invention. Please refer to FIG. 1 and FIG. 4. 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 and the second conductive portion 22 have a first reaction region 23 and a second reaction region 24, respectively. Next, in step S2, an insulating and waterproof layer 30 is formed on the conductive layer 20, partially covering the first conductive portion 21 and the second conductive portion 22 of the conductive layer 20, and the first conductive portion 21 and the second conductive portion 22 are formed. Partial exposure, in which the first conductive portion 21 and the second conductive portion 22 are exposed outside the insulating and waterproof layer 30 are respectively configured as a first reaction area 23 and a second reaction area 24. In this embodiment, the insulating and waterproof layer 30 is covered on the conductive layer 20 by means of, for example, but not limited to, screen printing or chemical vapor deposition technology, and a part of the uncovered conductive layer 20 is assembled. The first reaction region 23 of the first conductive portion 21 and the second reaction region 24 of the second conductive portion 22 are formed. Among them, the first reaction region 23 of the first conductive portion 21 and the second reaction region 24 of the second conductive portion 22 are relatively adjacent to each other at a fine interval, which is beneficial to the miniaturization of the overall structure. In a preferred embodiment, except that the first reaction region 23 and the second reaction region 24 are located at respective ends of the first conductive portion 21 and the second conductive portion 22, respectively, the first conductive portion 21 and the second conductive portion 22 is not covered by the insulating and waterproof layer 30 at the other ends opposite to the first reaction zone 23 and the second reaction zone 24, and is respectively configured as a working electrode connection area 25 and a pair of electrode connection areas 26 for The sensing circuit is formed, but it does not limit the necessary technical features of this case, and is not repeated here. Thereafter, in step S3, an ammonium ion sensing layer 40 and a pH sensing layer 50 are formed on the first reaction region 23 of the first conductive portion 21 and the second reaction region 24 of the second conductive portion 22 of the conductive layer 20, respectively. . In this embodiment, the insulating and waterproof layer 30, the ammonium ion sensing layer 40, and the pH sensing layer 50 collectively cover the conductive layer 20. Therefore, the insulating and waterproof layer 30, the ammonium ion sensing layer 40, and the pH sensing layer 50 The order of forming the conductive layer 20 is not limited, and it 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 ammonium ion sensing layer 40 and the pH sensing layer 50. In this embodiment, the electrolyte filling area is further defined by the opening 61 of the septum 60. The septum 60 is arranged around the ammonium ion sensing layer 40, the pH sensing layer 50, and the electrolyte layer 70, so that The electrolyte layer 70 penetrates the opening 61 and is contained in the inner peripheral surface of the opening 61 and is in contact with the ammonium ion sensing layer 40 and the pH 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 filling region defined by filling a 0.01 M trishydroxymethylaminomethane aqueous solution in the inner peripheral surface of the opening 61 of the separator 60. Finally, in step S5, a gas-permeable layer 80 is formed on the electrolyte layer 70 and is attached to the separator 60, so that the electrolyte layer 70 is held on the gas-permeable layer 80, the ammonium ion sensing layer 40, and the pH sensing layer. Between 50, that is, the electrolyte layer 70 is accommodated in the electrolyte-filled area defined in the inner peripheral surface of the opening 61 of the separator 60. In this embodiment, the gas permeable layer 80 may be, but not limited to, a polytetrafluoroethylene gas permeable layer with a thickness of 10 μm.

In this embodiment, the conductive layer 20 can be formed on the plane 11 of the electrically insulating substrate 10 by, for example, but not limited to, screen printing or sputtering techniques. The first conductive region 21 and the second conductive region 22 of the conductive layer 20 are respectively covered by the ammonium ion sensing layer 40 and the pH sensing layer 50, and the first reaction region 23 and the second reaction region 24 are ammonium ions ( The NH ₄ ⁺ ) reaction electrode region and the hydroxide ion (OH ⁻ ) reaction electrode region, and the rest are covered and protected by the insulating and waterproof layer 30. In a preferred embodiment, the first conductive portion 21 and the second conductive portion 22 are opposite to each other in the first reaction area 23 and the second reaction area 24 covered by the ammonium ion sensing layer 40 and the pH sensing layer 50. One end further has a working electrode connection area 25 and a pair of electrode connection areas 26 respectively, and is connected to a measurement connection line (not shown) to form a sensing circuit. In this embodiment, the conductive layer 20 may be, for example, but not limited to, a sputtered metal film, and the material thereof may be selected from screen-printed silver-carbon conductive mixed paste, gold paste, platinum paste, silver paste, conductive carbon paste, gold , Palladium, platinum, gold-palladium alloy, silver, or a combination thereof. The electrically insulating substrate 10 may be composed of, but not limited to, polyethylene terephthalate (PET) or a ceramic substrate. In one embodiment, the conductive layer 20 is formed on the electrically insulating substrate 10 in a printed manner, and then dried at, for example, 60 ° C. to 140 ° C.

In this embodiment, the first reaction region 23 of the first conductive portion 21 of the conductive layer 20 is covered by the ammonium ion sensing layer 40, and the second reaction region 24 of the second conductive portion 22 is covered by the pH sensing layer 50. covering, the first reaction zone 23 and the second reaction zone 24 are formed an ammonium ion (NH ₄ ⁺⁾ and hydroxide ions (OH ^-) electrode reaction zone, for delivering the ammonium ion sensing layer 40 and the pH sensing The voltage change caused by the measured electrochemical film potential between the layers 50 is transmitted through the working electrode connection region 25 of the first conductive portion 21 of the conductive layer 20 and the counter electrode connection region 26 of the second conductive portion 22, respectively. The number is passed to the measurement connection line. In one embodiment, the measuring connection line is further connected to a measuring instrument (not shown), which can display and calculate the ammonia concentration of the corresponding sensing voltage change for the convenience of subsequent users. .

In addition, in this embodiment, the insulating waterproof layer 30 may be made of, for example, but not limited to, a material having electrical insulation and water resistance, such as a para-xylene polymer, a screen-printed insulating glue, a screen-printed UV insulating glue, and the like. In one embodiment, the insulating and waterproof layer 30 is formed by coating with a screen printing insulating glue and dried at, for example, 60 ° C. to 140 ° C. The insulating and waterproof layer 30 partially covers the first of the conductive layer 20. The conductive portion 21 and the second conductive portion 22, and the first conductive portion 21 and the second conductive portion 22 are partially exposed to form a first reaction area 23 and a second reaction area 24, respectively, for the ammonium ion sensing layer 40, respectively. And covered by the pH sensing layer 50. In a preferred embodiment, the first and second reaction areas 23 and 24 covered by the ammonium ion sensing layer 40 and the pH sensing layer 50 in the first conductive portion 21 and the second conductive portion 22 are connected to each other, respectively. The insulation is isolated, and is arranged adjacent to each other with a small pitch to facilitate the miniaturization of the sensing electrode 1.

In the embodiment of the present invention, the ammonium ion sensing layer 40 and the pH sensing layer 50 may be formed by, for example, but not limited to, a droplet coating method, a sputtering method, an electrodeposition method, or a screen printing thick film technology. In this embodiment, the ammonium ion sensing layer 40 formed on the first reaction region 23 of the first conductive portion 21 of the conductive layer 20 is an ammonium ion selective film, and its constituent material includes, for example, but is not limited to Ionophore, plasticizer, heat-resistant resin, or a combination thereof. In a preferred embodiment, the ammonium ion sensing layer 40 further includes a cation exchanger, and the weight of each component in the ammonium ion sensing layer 40 may be, for example, but not limited to, a weight percentage including an ionophore between 0.2 wt. % To 5 wt%, plasticizer weight percentage between 50 wt% and 70 wt%, heat resistant resin weight percentage between 30 wt% and 60 wt%, and cation exchanger weight percentage Between 0.1 wt% and 2.5 wt%. The mixed liquid composed of the foregoing ionophore, plasticizer, heat-resistant resin, and cation exchanger is droplet-coated on the first conductive part 21 of the conductive layer 20 by a droplet coating method to form an ammonium ion sensing layer 40. For the exposed part, the volume of the droplet is between 10µL and 50µL, and it is dried at 30 ° C to 60 ° C for 2 to 10 hours, and then dried at 40 ° C to 60 ° C under vacuum for 6 to 18 hours. That is, the fabrication of the ammonium ion sensing layer 40 is completed.

On the other hand, the pH sensing layer 50 can deposit iridium oxide (IrO ₂ ) on the second conductive layer 20 by using an electrodeposition method such as, but not limited to, electrochemical chronoamperometry or cyclic voltammetry. A second reaction zone 24 is exposed on the portion 22 to form a pH sensing layer 50. In one embodiment, the pH sensing layer 50 is a second reaction zone 24 that is exposed by a chronoamperometry method to deposit iridium oxide (IrO ₂ ) on the second conductive portion 22 of the conductive layer 20 to form the pH sensing layer 50. , Where the current density ranges from 0.2 mA / cm ² to 5 mA / cm ² . In another embodiment, the pH sensing layer 50 may use cyclic voltammetry to deposit iridium oxide (IrO ₂ ) on the second conductive portion 22 of the conductive layer 20 to form a second exposed portion of the pH sensing layer 50. In the reaction zone 24, the voltage range can be between -0.2 V and 1.3 V, the scan rate can be between 10 mV / s and 100 mV / s, and the number of scans can be between 10 and 100. In one embodiment, the pH sensing layer 50 after electrodeposition is completed, and the excess plating solution can be washed with deionized water first, and then placed at 80 ° C for 1 hour, and the excess moisture is dried to complete the process. Fabrication of the pH sensing layer 50. In this embodiment, the composition of the plating solution used when forming the pH sensing layer 50 may be, but is not limited to, containing iridium chloride (IrCl _x ), where X is 3-4, 30 wt% hydrogen peroxide, oxalic acid, 3 M potassium carbonate and deionized water, wherein the weight percentage of iridium chloride (IrCl _x ) is between 0.05 wt% and 0.18 wt%, and the weight percentage of 30 wt% hydrogen peroxide is between 0.5 wt% and 1 wt%. The weight percentage of oxalic acid is between 0.2 wt% and 0.6 wt%, the weight percentage of 3 M potassium carbonate is between 6 wt% and 12 wt%, and the weight percentage of deionized water is between 80 wt% and 90 wt%.

In the foregoing embodiment, the septum 60 is circumferentially arranged around the ammonium ion sensing layer 40 and the pH sensing layer 50. The inner peripheral surface of the opening 61 of the septum 60 is further defined as an electrolyte-filled area, 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 ammonium ion sensing layer 40 and the pH sensing layer 50, and then pressed and placed for 12 hours by a roller compactor to make it adhere more firmly. The opening 61 of the septum 60 The inner peripheral surface is assembled 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 or ammonium chloride aqueous solution, the concentration range is between 0.01 M to 1 M. In one embodiment, it can be made by solid electrolyte. For example, it is but not limited to Agarose, Polyacrylamide, Gelatin, or calcium alginate ( Calcium alginate) and other gel materials to de-attach the liquid electrolyte. In a preferred embodiment, a 0.01 M trimethylolaminomethane aqueous solution is used, and the dispensing volume is fixed to 500 µL by a dispenser, and the opening 61 (ie, the electrolyte filling area) of the septum 60 is filled. Then, 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 laminated in the middle by a bonding jig. Above the separator 60 and covering the electrolyte layer 70, the electrolyte layer 70 is encapsulated in the opening 61 of the intermediate separator 60 to constitute the sensing electrode 1 of the present case.

In summary, the present invention provides a planar ammonia-selective sensing electrode and a manufacturing method thereof. The droplet coating method, sputtering method, electrodeposition method or screen printing thick film technology is used to planarize the ammonium ion sensing layer and hydroxide ion sensing layer on a conductive layer to improve accuracy. And greatly reduce the volume of the sensing electrode. At the same time, the flat-type ammonia-selective sensing electrode has high selectivity and sensitivity for applications in medicine, biochemistry, chemistry, agriculture, environment, and other fields, such as monitoring the changes in the concentration of ammonia nitrogen in the cultivation of hydroponic plants and the concentration of ammonia nitrogen in human sweat Changes, aquaculture water quality monitoring, or specific enzymes can be combined to detect specific biological indicators (such as creatine peptone). And its structure is small and simple, the process is simple, and the cost is low, which is more conducive to the purpose of providing disposable sensing electrodes.

1: Planar ammonia-selective sensing electrode (abbreviated as sensing electrode) 10: Electrically insulating substrate 11: Flat 20: Conductive layer 21: First conductive portion 22: Second conductive portion 23: First reaction zone 24: Second reaction Zone 25: Working electrode connection area 26: Counter electrode connection area 30: Insulation and waterproof layer 40: Ammonium ion sensing layer 50: pH sensing layer 60: Septum 61: Opening 70: Electrolyte layer 80: Gas breathable layer S1 ~ S5: Step

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

FIG. 2 is a voltage sensing curve showing an exemplary sensing voltage of one of the planar ammonia-selective sensing electrodes of the present case.

FIG. 3 is a calibration curve illustrating the relationship between the voltage of the sensing data and the ammonia concentration of the planar ammonia-selective sensing electrode and the conventional ammonia sensing electrode in the preferred embodiment of the present invention.

FIG. 4 is a flowchart illustrating a method for manufacturing a planar ammonia-selective sensing electrode according to a preferred embodiment of the present invention.

Claims (11)

A planar ammonia selective 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 at least a first conductive portion And at least a second conductive portion, the first conductive portion and the second conductive portion are insulated from each other, and are respectively provided with a first reaction zone and a second reaction zone; an ammonium ion sensing layer is disposed on the first Over a reaction zone; a hydroxide ion sensing layer disposed on the second reaction zone; and an electrolyte layer disposed and covering the ammonium ion sensing layer and the hydroxide ion sensing layer on. The flat-type ammonia-selective sensing electrode as described in claim 1, further comprising an insulating and waterproof layer disposed on the conductive layer, partially covering the first conductive portion and the second conductive portion, and making the first conductive portion The conductive portion and the second conductive portion are respectively assembled to constitute the first reaction region and the second reaction region. The planar ammonia-selective 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 ammonium ion sensing layer and the hydroxide ion sensing layer, and the electrolyte layer is contained in the inner peripheral surface of the opening. The flat-type ammonia-selective sensing electrode according to claim 3, further comprising a gas permeable layer, which is arranged and covered on the electrolyte layer, and is attached to the septum, so that the electrolyte layer is kept in the gas. Between the gas-permeable layer and the ammonium ion sensing layer and the hydroxide ion sensing layer. The planar ammonia-selective sensing electrode according to claim 1, wherein the hydroxide ion sensing layer is a pH sensing layer. A method for manufacturing a planar ammonia-selective 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 at least A first conductive portion and at least a second conductive portion, the first conductive portion and the second conductive portion are insulated from each other, and are respectively provided with a first reaction region and a second reaction region; (b) forming one An ammonium ion sensing layer and a hydroxide ion sensing layer covering the first reaction zone and the second reaction zone; and (c) forming an electrolyte layer covering the ammonium ion sensing layer and On the hydroxide ion sensing layer. The method for manufacturing a planar ammonia-selective sensing electrode according to claim 6, wherein the step (b) further includes a step (b1) forming an insulating and waterproof layer on the conductive layer, and partially covering the first conductive portion. And the second conductive portion, and the first conductive portion and the second conductive portion are respectively combined to form the first reaction region and the second reaction region. The method for manufacturing a planar ammonia-selective sensing electrode according to claim 6, wherein the step (c) further includes a step (c1) providing a separator with an opening, and bonding the separator to the electrical device The at least one plane of the insulating substrate is such that the separator is disposed on the periphery of the ammonium ion sensing layer and the hydroxide ion sensing layer, and the electrolyte layer is contained in the inner peripheral surface of the opening. The method for manufacturing a flat-type ammonia-selective sensing electrode as described in claim 8, further comprising a step (d) forming a gas-permeable layer on the electrolyte layer, and bonding the gas-permeable layer to the separator to keep the electrolyte layer Within the inner peripheral surface of the opening of the septum. The method for manufacturing a planar ammonia-selective sensing electrode according to claim 6, wherein the hydroxide ion sensing layer is a pH sensing layer. The method for manufacturing a planar ammonia-selective sensing electrode according to claim 6, wherein the ammonium ion sensing layer and the hydroxide ion sensing layer in step (b) are permeated by a droplet coating method or sputtering Method, electrodeposition method or screen printing thick film technology.