Abstract:
The present invention discloses a reference electrode. According to the invention, a capillary structure is plugged in a solid state electrolyte layer of the reference electrode. By capillary phenomenon, a test solution is sucked to the solid state electrolyte layer to have reaction. Therefore, according to the invention, a test solution can be measured by simply placing the capillary structure of the reference electrode into the test solution. The lifetime of the reference electrode can be greatly extended.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention is generally related to a reference electrode. 
         [0003]    2. Description of the Prior Art 
         [0004]    Accompanying with technology advance and living requirements, many electronic and chemical measurement devices become smaller. Thus, in order to fulfill the needs in delicate devices, many fabrication methods and tools are improved and invented continuously. 
         [0005]    The common reference electrode is made by covering electrolyte solution with glass or ceramics. However, such a reference electrode is bulky because it is made of glass or ceramics and thus it has problems like difficulty in fabrication, easily damaged structure, high cost, etc. 
         [0006]    Furthermore, the traditional reference electrode has to be placed in a test solution. This causes the electrolyte solution to vanish easily. On the other hand, the reference electrode is apt to be corroded by test solutions when dipping in the solutions. It results in device damage. 
       SUMMARY OF THE INVENTION 
       [0007]    In light of the above background, in order to fulfill the requirements of the industry, the present invention provides a reference electrode to solve the problems occurred in the prior art. 
         [0008]    One object of the present invention is to provide a reference electrode, comprising a substrate, a solid state electrolyte layer provided on the substrate, a conducting structure, and a capillary structure. The solid state electrolyte layer is polymerized colloidal electrolyte solution. The conducting structure and the capillary structure contact with the solid state electrolyte layer, separately. A test solution is sucked by the capillary structure to reach the solid state electrolyte layer to have reaction. Therefore, the measurement can be performed by simply placing the capillary structure into the test solution. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIGS. 1-4  show schematic diagrams illustrating the structure of a reference electrode; 
           [0010]      FIG. 5  shows a schematic diagram illustrating the structure of a sensing device; 
           [0011]      FIGS. 6 and 7  show schematic diagrams illustrating the structure of a working electrode; and 
           [0012]      FIGS. 8-11  show schematic diagrams illustrating the processes of fabricating a reference electrode. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0013]    What is probed into the invention is a reference electrode. Detail descriptions of the steps and compositions will be provided in the following in order to make the invention thoroughly understood. Obviously, the application of the invention is not confined to specific details familiar to those who are skilled in the art. On the other hand, the common structures or steps that are known to everyone are not described in details to avoid unnecessary limits of the invention. Some preferred embodiments of the present invention will now be described in greater detail in the following. However, it should be recognized that the present invention can be practiced in a wide range of other embodiments besides those explicitly described, that is, this invention can also be applied extensively to other embodiments, and the scope of the present invention is expressly not limited except as specified in the accompanying claims. 
         [0014]    The invention provides a reference electrode, comprising a substrate, a solid state electrolyte layer provide on the substrate, a conducting structure, and a capillary structure. The solid state electrolyte layer is polymerized colloidal electrolyte solution. The conducting structure and the capillary structure contact with the solid state electrolyte layer, separately. When the capillary structure is placed in a test solution, the ions in the test solution are sucked by the capillary structure to reach the solid state electrolyte layer to have ion exchange with the ions in the solid state electrolyte layer. Then, the solid state electrolyte layer performs ion exchange with the conducting structure. Thus, the back-end signal processing device can analyze the test solution according to the ion exchange result of the conducting structure. The reference electrode according to the invention can achieve the above purpose by various structures. 
         [0015]    Referring to  FIG. 1 , the reference electrode  100  comprises a substrate  110 , a solid state electrolyte layer  120 , a conducting structure  130 , and a capillary structure  140 . The conducting structure  130  is a conducting wire and the solid state electrolyte layer  120  is polymerized colloidal electrolyte solution. The solid state electrolyte layer  120  is located on the substrate  100  and the conducting structure  130  and the capillary structure  140  are placed in the colloidal electrolyte solution before polymerization. 
         [0016]      FIG. 2  shows another structural schematic diagram of a reference electrode  100  where the solid state electrolyte layer  120  and the conducting structure  130  are both on the substrate  110  and contact with each other. The conducting structure  130  is a conducting layer and the capillary structure  140  is placed in the colloidal electrolyte solution before polymerization. 
         [0017]    As shown in  FIG. 3 , the conducting structure  130  is a conducting layer positioned between the substrate  110  and the solid state electrolyte layer  120 . The capillary structure  140  is placed in the colloidal electrolyte solution before polymerization. 
         [0018]    As shown in  FIG. 4 , the solid state electrolyte layer  120  is fixed in a groove of the substrate  110 . The conducting structure  130  and the capillary structure  140  are both on the substrate  110  and separately connect to the solid state electrolyte layer  120 . 
         [0019]    Furthermore, as shown in  FIG. 5 , a sensing device to measure a test solution  190  has to comprise the above mentioned reference electrode  100  and a working electrode  150 . When the working electrode  150  and the capillary structure  140  of the reference electrode  100  are both placed in the test solution  190  at the same time, the test solution  190  is sucked to the solid state electrolyte layer  120  to have reaction through the capillary structure  140 . Thus, an electrical potential difference is generated between the reference electrode  100  and the working electrode  150 . 
         [0020]    As shown in  FIG. 6 , the working electrode  150  comprises a substrate  152 , an indium tin oxide layer (ITO)  154 , a sensing layer  156  and a sheathing layer  158 . The indium tin oxide layer  154  is positioned on the substrate  152  and the sensing layer  156  is on the indium tin oxide layer  154 . The sheathing layer  158  is positioned on the area besides the sensing layer  156 . Thus, the sensing layer  156  can be in contact with the test solution and also the other portion of the working electrode  150  can be protected. 
         [0021]    In order to measure the different compositions in the test solution  190 , the sensing layer  156  comprises one film selected from the group consisting of the following or any combination thereof: potassium sensing film, sodium sensing film, chlorine sensing film, ammonium sensing film, urea enzyme film, creatinine enzyme film, and glucose enzyme film. Besides, the sheathing layer can be of thermosetting material, such as epoxy compounds. In addition, the substrate  152  of the working electrode  150  comprises one substance selected from the group consisting of the following or combination thereof: polycarbonate, polyester, polyether, polyamide, polyurethane, polyimide, polyvinyl chloride (PVC), glass, glass fiber plate, ceramics, polyethylene terephthalate (PET). 
         [0022]    As shown in  FIGS. 5 and 6 , the reference electrode  100  and the working electrode  150  separately connect to a signal processing device  170 . The working electrode  150  connects to the signal processing device  170  via a conducting wire  160  and the conducting wire  160  connects to the indium tin oxide layer  154  of the working electrode  150 . The signal processing device  170  receives and processes the signals outputted by the reference electrode  100  and the working electrode  150  so as to analyze the test solution  190 . 
         [0023]    Moreover, as shown in  FIGS. 5 and 7 , the working electrode  150  can further comprise a detachable element to replace the working electrode  150  with different one. The working electrode  150  can be reused. 
         [0024]    According to the above mentioned structure of the reference electrode, the invention provides a method for fabricating a reference electrode, comprising the following steps. As shown in  FIG. 8 , at first in step  210 , a substrate is provided. In step  220 , the substrate is adhered with colloidal electrolyte solution. Then, in step  230 , a capillary structure is placed in the colloidal electrolyte solution. In step  240 , the colloidal electrolyte solution polymerizes to form a solid state electrolyte layer. As shown in  FIG. 9 , before step  240 , a step  232  to plug a conducting wire in the colloidal electrolyte solution before polymerization is performed to form the reference electrode in  FIG. 1 . 
         [0025]    As shown in  FIG. 10 , after the step  240  in  FIG. 8 , a step  242  to form a conducting layer on the substrate can be performed where the conducting layer connects to the solid state electrolyte layer. Thus, the reference electrode in  FIG. 2  can be formed. 
         [0026]    Furthermore, as shown in  FIG. 11 , before the step  220  in  FIG. 8 , a step  212  to form a conducting layer on the substrate can be performed so as to have the conducting layer positioned between the substrate and the solid state electrolyte layer after the substrate is adhered with the colloidal electrolyte solution. Thus, the reference electrode in  FIG. 3  can be formed. Besides, when the substrate is adhered with colloidal electrolyte solution in step  220 , the colloidal electrolyte solution can be fixed in the groove of the reference electrode to form the reference electrode in  FIG. 4 . 
         [0027]    The conducting layer can be formed by screen printing. In addition, the conducting structure comprises silver (Ag) and silver chloride (AgCl). The substrate of the reference electrode comprises one substance selected from the group consisting of the following or combination thereof: polycarbonate, polyester, polyether, polyamide, polyurethane, polyimide, polyvinyl chloride (PVC), glass, glass fiber plate, ceramics, polyethylene terephthalate (PET). The solid state electrolyte layer comprises potassium chloride (KCl) and polymer colloid where the polymer colloid covers potassium chloride. 
         [0028]    Obviously many modifications and variations are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims the present invention can be practiced otherwise than as specifically described herein. Although specific embodiments have been illustrated and described herein, it is obvious to those skilled in the art that many modifications of the present invention may be made without departing from what is intended to be limited solely by the appended claims.