BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional diagram of a conventional detecting device including a working-electrode and a reference electrode.
FIG. 2 is a sectional diagram of a reference electrode according to an embodiment of this invention.
FIG. 3 is a sectional diagram of a working electrode according to an embodiment of this invention.
FIG. 4 is a schematic-sectional diagram of a detecting device according to an embodiment of this invention.
FIG. 5 is a schematic diagram showing the measuring instrument according to an embodiment of this invention.
FIG. 6 is a schematic diagram showing the measuring instrument according to another embodiment of this invention, which is suitable for small message measurement.
DETAILED DESCRIPTION OF THE INVENTION
For understanding this invention better, the following employs drawings to explain the various embodiments according to this invention. A reference electrode provides a fixed and stable reference potential, which is not affected by environmental parameters, acidity, alkalinity, and different test solutions. Usually, a dry reference electrode is employed. FIG. 2 shows the sectional diagram of a dry reference electrode 100, which includes an Ag/AgCl electrode 130 covered with a polymeric layer 140, and employs a lead 110 electrically connected into an external circuit, and a protective layer 120 seals the joint to avoid oxidation. The polymeric layer 140 includes a polymer and ionic compound mixing with the polymer. When the polymeric layer 140 is immersed into a test solution, the polymeric layer 140 exchanges ions with the test solution, and exchanges ions with the Ag/AgCl electrode 130, so that the Ag/AgCl electrode 130 is protected. The dry reference electrode 100 is made easily, maintained easily and high efficient.
According to an embodiment, the polymeric layer 140 includes Carboxylated poly-vinyl-chloride (PVC-COOH), Bis(2-ethylhexyl) sebacate and salt with ratios of 33%, 66% and 1% respectively, and mixes with Tetrahydrofuran (THF), where the salt is potassium chloride or sodium chloride because the potassium and sodium ions have high mobility.
A working electrode is sensitive to the ion concentration, usually, which contacts with solution directly to detect the ion concentration. FIG. 3 shows the sectional diagram of a contact sensing electrode 200, which includes a conductive layer 230 on a substrate 220, a sensing membrane 240 on part surface of the conductive layer 230 and a protective layer 250 covering the conductive layer 230 but exposing the sensing membrane 240, and connects to a lead 210 electrically connected into an external circuit. When the sensing membrane 240 contacts with an ion solution, the sensing membrane 240 detects the ion concentration, and transforms to an electric message, and transmit the electric message to the conductive layer 230, and sends the electric message to the lead 210 electrically connected into external measurement circuit (not shown in FIG. 3). According to an embodiment of this invention, the conductive layer 230 is a metallic oxide, like tin oxide (SnO2), and the substrate 220 is a glass substrate, and the protective layer 250 is epoxy resin.
It needs to emphasize the sensing membrane 240, which includes different elements for a different test solution. The metallic oxide film, like SnO2, detects the pH of the test solution, and the sensing membrane 240 with the polymer membrane covering with an ionic compound detects the ion concentration corresponding to the ionic compound, like the sensing membrane 240 covering with potassium, sodium and chloride compound to detect potassium, sodium and chloride concentration respectively.
FIG. 4 shows the schematic diagram of an ion concentration-detecting device, which includes a link element 260, like a replaceable link element, binds a reference electrode 100 and a working electrode, like a contact sensing electrode 200. It is easy to replace the contact sensing electrode 200 to detect a different ion concentration.
FIG. 5 is a basic measurement instrument according to an embodiment of this invention to detect the ion concentration. The lead 110 connects the cathode of a voltmeter 400 to a reference electrode 100, and the lead 210 connects the anode of the voltmeter 400 to a contact sensing electrode 200, and the reference electrode 100 and the contact sensing electrode 200 are immersed in a test solution 300 forming a circuit. When the reference electrode 100 and the contact sensing electrode 200 exchange ions with solution to induce a potential difference. The voltmeter 400 measures the induced potential difference to obtain the ion concentration of the test solution 300.
FIG. 6 is another measurement instrument according to an embodiment of this invention to detect the ion concentration for a small message measurement. The leads 110 and 210 connect to a volt amplifier 410, and the volt amplifier 400 to a digital voltmeter 420. Moreover, for detecting the continuous variation of the ion concentration, the digital voltmeter 420 connects to a data processor 430 to record the continuous data of ion concentration, where the volt amplifier 410 and the digital voltmeter 420 connect a common ground wire to avoid noising.
Although the present invention has been explained in relation to its preferred embodiment, it is to be understood that other modifications and variation can be made without departing the spirit and scope of the invention as claimed.
Patent Application
20080053826
