CA1127714A - Method of making and structure for a solid state ion responsive and reference electrodes - Google Patents
Method of making and structure for a solid state ion responsive and reference electrodesInfo
- Publication number
- CA1127714A CA1127714A CA317,921A CA317921A CA1127714A CA 1127714 A CA1127714 A CA 1127714A CA 317921 A CA317921 A CA 317921A CA 1127714 A CA1127714 A CA 1127714A
- Authority
- CA
- Canada
- Prior art keywords
- pellet
- layer
- electrode
- ion
- set forth
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/28—Electrolytic cell components
- G01N27/30—Electrodes, e.g. test electrodes; Half-cells
- G01N27/333—Ion-selective electrodes or membranes
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/28—Electrolytic cell components
- G01N27/30—Electrodes, e.g. test electrodes; Half-cells
- G01N27/36—Glass electrodes
Abstract
ABSTRACT
A solid state ion concentration measuring electrode having the ion concentration measuring electrode structure formed by an outer ion sensitive layer deposited by RF
sputtering on a substantially thermally matched supporting solid electrolyte layer. The reference electrode is similarly formed by depositing an outer layer of glass onto a supporting solid electrolyte layer by RF sputtering with the temperature expansion of the glass and supporting solid electrolyte structure being selected to produce a differen-tial expansion causing random cracking of the glass layer during temperature cycling of the reference electrode. A
combination structure is provided wherein the ion concentra-tion measuring electrode and the reference electrode are combined in an integrated package. A thermal compensating element may also be included in the integrated package.
A solid state ion concentration measuring electrode having the ion concentration measuring electrode structure formed by an outer ion sensitive layer deposited by RF
sputtering on a substantially thermally matched supporting solid electrolyte layer. The reference electrode is similarly formed by depositing an outer layer of glass onto a supporting solid electrolyte layer by RF sputtering with the temperature expansion of the glass and supporting solid electrolyte structure being selected to produce a differen-tial expansion causing random cracking of the glass layer during temperature cycling of the reference electrode. A
combination structure is provided wherein the ion concentra-tion measuring electrode and the reference electrode are combined in an integrated package. A thermal compensating element may also be included in the integrated package.
Description
1;~7714 ~ACKGROUND OF THE IhVENTION
1. Field Of The Invention -The present invention relates to ion concentration measuring apparatus. More specifically, the present inven-tion is directed to a solid state ion responsive electrode and reference electrode.
s ?. Description Of The Prior Art Conventional ion concentration measuring electrode structure have usually used a glass measuring electrode, a reference electrode and a thermal compensator. For examp1e, various types of special glasses have been used to measure the pH of aqueous solutions. In making these glass elec-trodes the pH sensitiv~ glass is usually fused to the end of a less expensive glass tube and is subsequently blown into a small bulb of about two to four mils thick. These "hand-blown" pH glass electrodes are fragile, have very high electrical impedance due to the thickness of the glass and are used for limited temperature ranges mainly because of the internal pressure developed by a liquid electrolyte fill which is subsequently introduced into the interior of the pH measuring electrod~ to provide an electrically conductive ion path. An example of a typical prior art pH
electrode apparatus is shown in U.S. Patent No, 3,405,048 of D J. Soltz issued Oct 9, 1968. These prior art glass electrodes are expensive mainly because of the extensive use of hignly skilled manual labor in the construction of the glass envelope and the subsequent filling thereof. A
somewhat similar construction is used in the construction of the prior art reference cell which additionally incredses the cost of the overdll couventional pH medsuring system.
Despite its disadvdntdges, the glass electrode has retained
1. Field Of The Invention -The present invention relates to ion concentration measuring apparatus. More specifically, the present inven-tion is directed to a solid state ion responsive electrode and reference electrode.
s ?. Description Of The Prior Art Conventional ion concentration measuring electrode structure have usually used a glass measuring electrode, a reference electrode and a thermal compensator. For examp1e, various types of special glasses have been used to measure the pH of aqueous solutions. In making these glass elec-trodes the pH sensitiv~ glass is usually fused to the end of a less expensive glass tube and is subsequently blown into a small bulb of about two to four mils thick. These "hand-blown" pH glass electrodes are fragile, have very high electrical impedance due to the thickness of the glass and are used for limited temperature ranges mainly because of the internal pressure developed by a liquid electrolyte fill which is subsequently introduced into the interior of the pH measuring electrod~ to provide an electrically conductive ion path. An example of a typical prior art pH
electrode apparatus is shown in U.S. Patent No, 3,405,048 of D J. Soltz issued Oct 9, 1968. These prior art glass electrodes are expensive mainly because of the extensive use of hignly skilled manual labor in the construction of the glass envelope and the subsequent filling thereof. A
somewhat similar construction is used in the construction of the prior art reference cell which additionally incredses the cost of the overdll couventional pH medsuring system.
Despite its disadvdntdges, the glass electrode has retained
- 2 -,, ~
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its popularity in the field of ion concentration measurement even after attempts to develop a solid state electrode sùch as the pH electrode shown in U S. Patent No. 3,498,901 of L. T. Metz et al since the response of the glass electrode is faster than other prior art devices with the glass elec-trode also having the broadest useful pH range. A more recent development using a multilayered solid state structure is shown in U.S. Patent No. 4~031,606 of E. L.
Szonntagh issued June 28, 1977. However, the structure 1~ shown therein includes an insulating substrate which adds to the complexity of the manufacturing process and the end ; product. However, in order to provide a low cost and even more useful ion concentration measuring system it is desir-able to produce a low impedance, high reliability and rela-tively unbreakable ion concentration measuring electrode having a simplified structure and method of manufacturing.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an improved solid state ion responsive electrode structure and reference electrode structure.
Another object of the present invention is to provide an improved combination ion concentration measuring elec-trode and reference electrode structure.
In accomplishing this and other objects, there has been provided, in accordance with the present invention, a solid state ion concentration and reference electrode structure and method of manufacturing having an ion measuring elec-trode with an electrical connection attached to a solid electrolyte layer and having an outer ion responsive layer attached to the solid electrolyte layer by RF sputtering.
In the reference electrode, an outer glass layer is support-ed on ~ soli;J electrolyte layer having an electrical connec-~' ,' ~,~
llZ7714 tion attached thereto. In the reference electrode, the glass layer has a coefficient of thermal expansion different from the supporting solid electrolyte layer while in the ion measuring electrode, the outer ion responsive layer is substantially thermally matched to the supporting electrolyte layer.
In accordance with the present invention, there is provided an ion responsive electrode comprising a solid elec-trolyte pellet, an electrical connection means in electrical contact with said pellet and an ion responsive layer on saia pellet and spaced from said connection means.
In accordance with the present invention, there is also provided a combination electrode comprising an ion respon-sive electrode, said ion responsive electrode including a solid electrolyte pellet, an electrical connection means in electrical contact with said pellet and an ion responsive layer on said pellet and spaced from said connection means; a second solid electrolyte pellet, an ion conducting path layer on said second electrolyte pellet and encapsulating means for supporting said first and second pellets in electrical isolation and for covering said first and second pellets while exposing a portion of said pH glass layer and said ion conducting path layer.
In accordance with the present invention, there is also provided a method of making an ion responsive electrode com-pri~ing the steps of forming a solid electrolyte pellet and depositing an ion responsive layer on said electrolyte pellet, said ion responsive layer having a coefficient of thermal expan-sion substantially matched with respect to a coefficient of thermal expansion of said electrolyte pellet to maintain the integrity of said ion responsive layer.
In accordance with the present invention, there is also provided a method of making a combination eleatrode com-prising the steps of forming a first solid electrolyte pellet, depositing an ion responsive layer on said electrolyte pellet, ~1;Z'7714 forming a second electrolyte pellet, depositing an ion con-ducting path layer on said second electrolyte pellet and encap-sulating said first and second pellets in a spaced apart electrically isolated relationship while exposing a portion of said ion responsive layer and said ion conducting path layer.
BRIEF DESCRIPTION OF ~HE DRAWINGS
A better understanding of the present invention may be had when the following detailed description is read in con-nection with the accompanying drawings, in which:
Fi:gure 1 is a pictorial illustration of a cross-section of an example of a reference electrode embodying the present invention, Figure 2 is a pictorial illustration of a cross-section of an apparatus used in the manufacturing of the reference electrode shown in Figure 1, Figure 3 is a pictorial illustration of a cross-section of an example of another reference electrode structure also embodying the present invention, Figure 4 is a pictorial illustration of a cross-section of an apparatus used in the manufacturing of the reference electrode shown in Figure 3, Figure 5 is a pictorial illustration of a cross-section of an ion concentration measuring electrode embodying the pre-~ent lnvention and using the apparatus shown in Figure 4, Figure 6 is a pictorial illustration of a cross-section of an example of a combination electrode having an ion responsive electrode, a reference electrode and thermal compensator embody-ing the present invention, Figures 7 and 8 are end views of the combination electrode shown in Yigure 6 showing different physical - 4a -. ., ,...::....
~ llZ7714 configurations, Figure 9 is a pictorial illustration of a cross-section of an example of a combination electrode having a plurality of ion responsive electrode, a reference electrode and a thermal compensator, and Figures 10 and 11 are end view of combination electrodes having a plurality of ion responsive electrodes and a refer-ence electrode showing different physical configurations.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to Figure 1 in more detail, there is shown a pictorial illustration of a cross-section of an example of a reference electrode embodying the present invention.
A solid pellet 2 of silver chloride (AgCl) forming an electrolyte layer has a silver strip 4 embedded therein.
An outer end 6 of the silver strip 4 is arranged to overlie an outer surface 8 of the pellet 2. An outer layer 10 of a suitable glass is RF sputtered on the exposed surface of the silver chloride layer 8. The glass material for the outer layer 10 is selected to have a coefficient of thermal expansion different from the supporting silver chloride pellet 2 whereby a subsequent temperature cycling of the multilaYer structure is effective to produce micro-scopic cracks in the outer glass layer. For example, borosilicate glass has a coefficient approximately 1/10 that of silver chloride. These cracks provide ion conduc-tion paths to the silver chloride layer from an aqueous solution in which the reference eIectrode is immersed during ion concentration measurements. A socket shell 12 is ar-ranged to enclose a single eIectrically conducting contact pin 14. The contact pin is electrically connected, e.g,, soldered, to the silver strip 4 of the multilayer structure.
112771~
An electrically insulating encapsulating, or potting, compound 18 is subsequently applied to the pellet struc-ture, the socket shell 12, the contact pin 14 to form a moisture-proof barrier, i.e., an hermetic seal, and to unite the elements into a rigid package. An open window, or hole, l9 is formed, e.g., by masking, through the potting compound 18 to expose the outer glass layer 10.
In Figure 2, there is shown a cross-section of an apparatus suitable for use in the manufacturing of the elec-trode shown in Figure 1. A silver-chloride powder 2A is located within a pellet molding shell 20 having an end plug 22. The internal diameter of the shell 20 is arranged to be the desired diameter of the pellet 2, e.g., one inch.
The silver strip 4 in the form of a narrow V is inserted into the powder 2A with the outer end 6 projecting from the powder 2A. A molding plate 24 having a right fit within the shell 20 is forced by a ram 26 against the powder 2A and strip 6 using a suitable pressure, e.g., 5000 to 20,000 psi, to form the pellet 2. The pellet 2 is subsequently RF sputtered by a conventional technique with the glass layer 10 and temperature cycled to produce cracks in the glass layer 10 as shown in Figure 1. The further manu-act~ring operations of attaching the pin 14 and potting the reference electrode and socket shell 12 into a unitary device are operations well-known in the art and no further description thereof is believed to be necessary.
In Figure 3, there is shown a pictorial illustration of a cross-section of another structure of a reference electrode also embodying the present invention. Similar reference number~ have been used for structural elements common with the structure shown in Figure 1. The reference llZ7 714 electrode structure shown in Figure 3 has a silver contact pin 30 with a head 32 embedded in the silver chloride pellet 2. This structure eliminates the separate silver strip 4 and contact pin 14 used in the structure shown in Figure 1. The further structure shown in Figure 3 includes the socket shell 12 and potting compount envelope 18 as shown in Figure 1.
Figure 4 is a cross-section of an apparatus suitable for use in the manufacturing of the electrode shown in Figure 3. In an apparatus similar to that shown in Figure :
2, silver chloride 2A is placed within the molding shell 20. The silver contact pin 30 is inserted into the powder 2A with the head 32 being completely covered by the powder 2A. A molding plate 34 having a tight fit within the shell : 15 20 is provided with a recess 36 closely conforming to the projecting leg of the contact pin 30. The length of the recess 36 is arranged to accommodate the projecting leg of the pin 30 to allow the plate 34 to compress the powder 2A without disturbing the position of the head 32 in the powder 2A. The ram 26 is used to force the plate 34 against the powder 2A as described above with respect to Figure 1.
The pellet 2 with the pin 30 is subsequently coated with an RF sputtered glass layer, temperature cycled and potted with the socket shell 12 using conventional techniques to achieve the unitary structure shown in Figure 3.
In Figure 5, there is shown a pictorial illustration of a cross-section of an exemplary ion responsive electrode embodying the present inyention and using the manufacturing apparatus shown in Figure 4. Similar reference numbers have been used in Figures 3, 4 and 5 to indicate similar structural elements although the structural combination of llZ77~.4 Figure 5 is directed toward a different device from that shown in Figure 3. A solid peIlet 2 of silver chloride (AgCl) forming an electrolyte layer has a head 32 of a silver contact pin 30 embedded therein using the manufactur-ing technique previously described with respect to Figure 4. An outer layer 40 of an ion responsive material, e.g., pH sensitive glass, is then RF sputtered by conven-tional means on the silver chloride pellet 2. The tempera-ture coefficient of the silver chloride and pH glass layer 40 are matched whereby the pH glass will not produce microscopic cracks as during normal temperature cycling, e.g., o to 100C, as in the case of outer glass layer used in the reference electrode previously described. For ex-B ample, Corning 1990 glass has a coefficient of thermal expansion approximately one-half that of silver chloride.
Other pH sensitive glasses or materials can be produced to even more closely match the coefficient of thermal expansion of the silver chloride pellet 2 by using glass formulas with the following characteristics: a high co-efficient of expansion can be achieved by using oxides such as Li2O, Na2O, K2O, Rb2O, Cs2O, 8aO and SrO while a low coefficient of expansion can be achieved by using SiO2, B2O3, A12O3, BeO and TiO2. Thus, the coefficient of thermal expansion of the silver chloride pellet 2 or other solid state electrolyte materials such as CuO, AgI, RbI, RbAg4I5, etc. can be matched to an even closer approximation to maintain the integrity of the responsive layer 40 if either the temperature cycling during the measurement operation or the electrolyte material layer imposes a need for such a match. The thickness of the pH
glass is approximately 10 to 10K A. The pellet 2 with the ~ c/~ 8 -contact pin 2 and the RF sputtered ion responsive layer 40 is subsequently combined with the socket shell 12 and potting envelope 18 to achieve a unified structure, including the window 19 exposing a portion of the ion responsive layer 40, using conventional techniques. It should be noted that ion responsive electrode can also be manufactured using the apparatus shown in Figure 2 to achieve a structure similar to that shown in Figure 1 with the ion responsive layer 40 replacing the cracked glass layer 10.
A separate thermal compensator structure (not shown) may be produced using an insulating substrate with a thermal sensitive element, e.g., resistor, diode, etc., mounted therein and having the same overall configuration as that used for the aforesaid reference and pH electrodes whereby the threé elements would be used concurrently as shown in the aforesaid Soltz 3,405,048 patent.
In order to further utilize the solid state nature of the electrodes of the present invention, an example of a combination structure having the reference electrode, the ion concentration measuring electrode and the thermal compensator integrated therein is shown in Figure 6. A
first silver chloride pellet 2C has a cracked glass layer 10 thereon and a silver contact pin 30A embedded therein as previously described with respect to Figures 3 and 4.
A second silver chloride pellet 2D has an ion responsive layer 40 thereon and a silver contact pin 30B embedded therein as previously described with respect to Figure 5.
A socket sheIl 44 which may advantageously be a larger size then the socket shell 12 shown in Figures 1, 3 and 5 to accommodate an additional number of connector pins is _ g _ llZ'77~4 provided adjacent to one side of the aforesaid pellet structures and surrounding the pins 30A, 30B.
A pair of additional electrical connector pins 46, 48 are located within the connector shell 24. The addi-s tional pins 46 and 48 are connected to a thermal compensator element 50 by separate wires 52 and 54, respectivelY~ whereby the thermal compensator element 50 is electrically connected across the additional pins 46 and 48. The thermal compensa-tor element 34 may be any suitable thermally responsive device, such devices being well-known in the art. Finally, an outer shell, or covering, of an electrically insulating ; potting compound 56 i5 provided to enclose the multi element structure and to space and to secure the pins 46 and 48, the element 50 and the pellets 2C and 2D while engaging the ; 15 connector shell 24. A first opening, or window, l9A is provided in the covering 56 to expose the cracked glass layer 10 of the reference electrode while a second opening l9B
is provided in the covering 40 to expose the ion responsive layer 40 of the ion responsive electrode structure.
In Figures 7 and 8 are end views of combined electrodes using the ~tructure of Figure 6 and showing various configura-tions for the windows l9A and l9B to accommodate desired operating and mechanical criteria for the combination electrode of Figure 6. Other configurations may be used by those skilled in the art without departing from the scope of the present invention.
In Figure 9, there is shown a pictorial illustration of a cross-section of an example of a multi-ion sensing electrode structure wherein a plurality of ion responsive electrodes are combined with a common reference electrode and a common thermal compensator. Thus, a first ion responsive electrode 60 using the previously discussed llZ~714 structure of either Figures 1 or 5 is provided with a first ion responsive outer layer, e.g., pH glass, while a second ion responsive electrode 62 using the previously discussed structure of either Figures 1 or 5 is provided with a second ion responsive outer layer, e.g., sodium ion selective glass. A shared, or common, reference electrode 64 and a thermal compensator 66 are also provided in the overall electrode structure. A socket shell 68 and thermal compensator connector pins 70, 72 are secured to the electrodes 60, 62, 64 by an electrically insulating and hermetic sealing envelope 74. A first window l9A for the cracked glass layer 40 of the reference electrode 64, a second window l9B for the first ion responsive electrode 60 and a third window l9C for the second ion responsive electrode 62 are provided in the hermetic envelope 74 by any suitable conventional technique. Figures 10 and 11 are end view of multi-ion electrode structures using the structure of Figure 9 and showing various configurations of the windows l9A, l9B and l9C. It should be noted that the structure shown in Figure 9 may be expanded to accommo-date more than two ion responsive electrode, more than one reference electrode and more than one thermal compensator, if desired.
MODE OF OPERATION
Since, in the RF sputtering process operation, the operating temperatures are below 200C, the preparation of the ion responsive electrode structure including the ion responsive layer is performed over a much smaller temperature range which further prevents the ion respon-s1~e 1ayer from cracking when it is cooled down to room temperature even if the ion responsive layer and the 112771~
electrolyte pellet do not have an exact temperature co-efficient match. Additionally, the thin, i.e., lO,000 A
maximum, ion responsive layer will stretch instead of cracking during temperature cycling to enable the electrode structure to withstand temperature cycling over a relatively wide temperature range, e.g., -70C to +200C even with a slight temperature coefficient mismatch. Inherently, the integrated electrode structure has a low im~edance due to the thinness of the outer ion responsive layer. An-other feature is an extreme ease of replacement whereby the ion responsive electrode, the reference electrode and the thermal compensator can be replaced as a single inexpensive unit. Further, since the delicate glass handling operations required for prior art electrodes have been eliminated, the high manufacturing repeatability of the product and the reduction of manufacturing rejects enhances the low manufacturing costs of either the separate electrodes shown in Figures l and 5 or the combinational electrode structure shown in Figures 5, 6 and 9. Finally, in addi-tion to savings in the amount of materials used for the thin layers of the multilayer structure, additional savings will be effected by the elimination of certain expensive metals which were necessary to previous blown glass electrodes because of the required glass-to-metal seals, e.g., platinum or other similar thermal property metals.
In order to enable the ion responsive electrode of the present invention either in a separate or combination embodiment to measure other than hydrogen ions, the ion responsive layer 40 would be changed to an appropriate ion responsive material. For example to measure fluoride llZ77~4 ion concentration, the layer 40 would be lanthanum fluoride.
Similarly, for potassium ions, potassium ion selective glass would be used, while for sodium ions, sodium ion selective glass would be used. The method of depositing the various materials for the ion responsive layer would be the same as that disclosed above for the pH electrode and the overall electrode structure would also be the same as that dis-closed for the pH electrode.
Accordingly, it may be seen that there has been provided, in accordance with the present invention, a solid state ion responsive and reference electrode structure having application in either a separate or a combination electrode construction.
llZ7ql~
its popularity in the field of ion concentration measurement even after attempts to develop a solid state electrode sùch as the pH electrode shown in U S. Patent No. 3,498,901 of L. T. Metz et al since the response of the glass electrode is faster than other prior art devices with the glass elec-trode also having the broadest useful pH range. A more recent development using a multilayered solid state structure is shown in U.S. Patent No. 4~031,606 of E. L.
Szonntagh issued June 28, 1977. However, the structure 1~ shown therein includes an insulating substrate which adds to the complexity of the manufacturing process and the end ; product. However, in order to provide a low cost and even more useful ion concentration measuring system it is desir-able to produce a low impedance, high reliability and rela-tively unbreakable ion concentration measuring electrode having a simplified structure and method of manufacturing.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an improved solid state ion responsive electrode structure and reference electrode structure.
Another object of the present invention is to provide an improved combination ion concentration measuring elec-trode and reference electrode structure.
In accomplishing this and other objects, there has been provided, in accordance with the present invention, a solid state ion concentration and reference electrode structure and method of manufacturing having an ion measuring elec-trode with an electrical connection attached to a solid electrolyte layer and having an outer ion responsive layer attached to the solid electrolyte layer by RF sputtering.
In the reference electrode, an outer glass layer is support-ed on ~ soli;J electrolyte layer having an electrical connec-~' ,' ~,~
llZ7714 tion attached thereto. In the reference electrode, the glass layer has a coefficient of thermal expansion different from the supporting solid electrolyte layer while in the ion measuring electrode, the outer ion responsive layer is substantially thermally matched to the supporting electrolyte layer.
In accordance with the present invention, there is provided an ion responsive electrode comprising a solid elec-trolyte pellet, an electrical connection means in electrical contact with said pellet and an ion responsive layer on saia pellet and spaced from said connection means.
In accordance with the present invention, there is also provided a combination electrode comprising an ion respon-sive electrode, said ion responsive electrode including a solid electrolyte pellet, an electrical connection means in electrical contact with said pellet and an ion responsive layer on said pellet and spaced from said connection means; a second solid electrolyte pellet, an ion conducting path layer on said second electrolyte pellet and encapsulating means for supporting said first and second pellets in electrical isolation and for covering said first and second pellets while exposing a portion of said pH glass layer and said ion conducting path layer.
In accordance with the present invention, there is also provided a method of making an ion responsive electrode com-pri~ing the steps of forming a solid electrolyte pellet and depositing an ion responsive layer on said electrolyte pellet, said ion responsive layer having a coefficient of thermal expan-sion substantially matched with respect to a coefficient of thermal expansion of said electrolyte pellet to maintain the integrity of said ion responsive layer.
In accordance with the present invention, there is also provided a method of making a combination eleatrode com-prising the steps of forming a first solid electrolyte pellet, depositing an ion responsive layer on said electrolyte pellet, ~1;Z'7714 forming a second electrolyte pellet, depositing an ion con-ducting path layer on said second electrolyte pellet and encap-sulating said first and second pellets in a spaced apart electrically isolated relationship while exposing a portion of said ion responsive layer and said ion conducting path layer.
BRIEF DESCRIPTION OF ~HE DRAWINGS
A better understanding of the present invention may be had when the following detailed description is read in con-nection with the accompanying drawings, in which:
Fi:gure 1 is a pictorial illustration of a cross-section of an example of a reference electrode embodying the present invention, Figure 2 is a pictorial illustration of a cross-section of an apparatus used in the manufacturing of the reference electrode shown in Figure 1, Figure 3 is a pictorial illustration of a cross-section of an example of another reference electrode structure also embodying the present invention, Figure 4 is a pictorial illustration of a cross-section of an apparatus used in the manufacturing of the reference electrode shown in Figure 3, Figure 5 is a pictorial illustration of a cross-section of an ion concentration measuring electrode embodying the pre-~ent lnvention and using the apparatus shown in Figure 4, Figure 6 is a pictorial illustration of a cross-section of an example of a combination electrode having an ion responsive electrode, a reference electrode and thermal compensator embody-ing the present invention, Figures 7 and 8 are end views of the combination electrode shown in Yigure 6 showing different physical - 4a -. ., ,...::....
~ llZ7714 configurations, Figure 9 is a pictorial illustration of a cross-section of an example of a combination electrode having a plurality of ion responsive electrode, a reference electrode and a thermal compensator, and Figures 10 and 11 are end view of combination electrodes having a plurality of ion responsive electrodes and a refer-ence electrode showing different physical configurations.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to Figure 1 in more detail, there is shown a pictorial illustration of a cross-section of an example of a reference electrode embodying the present invention.
A solid pellet 2 of silver chloride (AgCl) forming an electrolyte layer has a silver strip 4 embedded therein.
An outer end 6 of the silver strip 4 is arranged to overlie an outer surface 8 of the pellet 2. An outer layer 10 of a suitable glass is RF sputtered on the exposed surface of the silver chloride layer 8. The glass material for the outer layer 10 is selected to have a coefficient of thermal expansion different from the supporting silver chloride pellet 2 whereby a subsequent temperature cycling of the multilaYer structure is effective to produce micro-scopic cracks in the outer glass layer. For example, borosilicate glass has a coefficient approximately 1/10 that of silver chloride. These cracks provide ion conduc-tion paths to the silver chloride layer from an aqueous solution in which the reference eIectrode is immersed during ion concentration measurements. A socket shell 12 is ar-ranged to enclose a single eIectrically conducting contact pin 14. The contact pin is electrically connected, e.g,, soldered, to the silver strip 4 of the multilayer structure.
112771~
An electrically insulating encapsulating, or potting, compound 18 is subsequently applied to the pellet struc-ture, the socket shell 12, the contact pin 14 to form a moisture-proof barrier, i.e., an hermetic seal, and to unite the elements into a rigid package. An open window, or hole, l9 is formed, e.g., by masking, through the potting compound 18 to expose the outer glass layer 10.
In Figure 2, there is shown a cross-section of an apparatus suitable for use in the manufacturing of the elec-trode shown in Figure 1. A silver-chloride powder 2A is located within a pellet molding shell 20 having an end plug 22. The internal diameter of the shell 20 is arranged to be the desired diameter of the pellet 2, e.g., one inch.
The silver strip 4 in the form of a narrow V is inserted into the powder 2A with the outer end 6 projecting from the powder 2A. A molding plate 24 having a right fit within the shell 20 is forced by a ram 26 against the powder 2A and strip 6 using a suitable pressure, e.g., 5000 to 20,000 psi, to form the pellet 2. The pellet 2 is subsequently RF sputtered by a conventional technique with the glass layer 10 and temperature cycled to produce cracks in the glass layer 10 as shown in Figure 1. The further manu-act~ring operations of attaching the pin 14 and potting the reference electrode and socket shell 12 into a unitary device are operations well-known in the art and no further description thereof is believed to be necessary.
In Figure 3, there is shown a pictorial illustration of a cross-section of another structure of a reference electrode also embodying the present invention. Similar reference number~ have been used for structural elements common with the structure shown in Figure 1. The reference llZ7 714 electrode structure shown in Figure 3 has a silver contact pin 30 with a head 32 embedded in the silver chloride pellet 2. This structure eliminates the separate silver strip 4 and contact pin 14 used in the structure shown in Figure 1. The further structure shown in Figure 3 includes the socket shell 12 and potting compount envelope 18 as shown in Figure 1.
Figure 4 is a cross-section of an apparatus suitable for use in the manufacturing of the electrode shown in Figure 3. In an apparatus similar to that shown in Figure :
2, silver chloride 2A is placed within the molding shell 20. The silver contact pin 30 is inserted into the powder 2A with the head 32 being completely covered by the powder 2A. A molding plate 34 having a tight fit within the shell : 15 20 is provided with a recess 36 closely conforming to the projecting leg of the contact pin 30. The length of the recess 36 is arranged to accommodate the projecting leg of the pin 30 to allow the plate 34 to compress the powder 2A without disturbing the position of the head 32 in the powder 2A. The ram 26 is used to force the plate 34 against the powder 2A as described above with respect to Figure 1.
The pellet 2 with the pin 30 is subsequently coated with an RF sputtered glass layer, temperature cycled and potted with the socket shell 12 using conventional techniques to achieve the unitary structure shown in Figure 3.
In Figure 5, there is shown a pictorial illustration of a cross-section of an exemplary ion responsive electrode embodying the present inyention and using the manufacturing apparatus shown in Figure 4. Similar reference numbers have been used in Figures 3, 4 and 5 to indicate similar structural elements although the structural combination of llZ77~.4 Figure 5 is directed toward a different device from that shown in Figure 3. A solid peIlet 2 of silver chloride (AgCl) forming an electrolyte layer has a head 32 of a silver contact pin 30 embedded therein using the manufactur-ing technique previously described with respect to Figure 4. An outer layer 40 of an ion responsive material, e.g., pH sensitive glass, is then RF sputtered by conven-tional means on the silver chloride pellet 2. The tempera-ture coefficient of the silver chloride and pH glass layer 40 are matched whereby the pH glass will not produce microscopic cracks as during normal temperature cycling, e.g., o to 100C, as in the case of outer glass layer used in the reference electrode previously described. For ex-B ample, Corning 1990 glass has a coefficient of thermal expansion approximately one-half that of silver chloride.
Other pH sensitive glasses or materials can be produced to even more closely match the coefficient of thermal expansion of the silver chloride pellet 2 by using glass formulas with the following characteristics: a high co-efficient of expansion can be achieved by using oxides such as Li2O, Na2O, K2O, Rb2O, Cs2O, 8aO and SrO while a low coefficient of expansion can be achieved by using SiO2, B2O3, A12O3, BeO and TiO2. Thus, the coefficient of thermal expansion of the silver chloride pellet 2 or other solid state electrolyte materials such as CuO, AgI, RbI, RbAg4I5, etc. can be matched to an even closer approximation to maintain the integrity of the responsive layer 40 if either the temperature cycling during the measurement operation or the electrolyte material layer imposes a need for such a match. The thickness of the pH
glass is approximately 10 to 10K A. The pellet 2 with the ~ c/~ 8 -contact pin 2 and the RF sputtered ion responsive layer 40 is subsequently combined with the socket shell 12 and potting envelope 18 to achieve a unified structure, including the window 19 exposing a portion of the ion responsive layer 40, using conventional techniques. It should be noted that ion responsive electrode can also be manufactured using the apparatus shown in Figure 2 to achieve a structure similar to that shown in Figure 1 with the ion responsive layer 40 replacing the cracked glass layer 10.
A separate thermal compensator structure (not shown) may be produced using an insulating substrate with a thermal sensitive element, e.g., resistor, diode, etc., mounted therein and having the same overall configuration as that used for the aforesaid reference and pH electrodes whereby the threé elements would be used concurrently as shown in the aforesaid Soltz 3,405,048 patent.
In order to further utilize the solid state nature of the electrodes of the present invention, an example of a combination structure having the reference electrode, the ion concentration measuring electrode and the thermal compensator integrated therein is shown in Figure 6. A
first silver chloride pellet 2C has a cracked glass layer 10 thereon and a silver contact pin 30A embedded therein as previously described with respect to Figures 3 and 4.
A second silver chloride pellet 2D has an ion responsive layer 40 thereon and a silver contact pin 30B embedded therein as previously described with respect to Figure 5.
A socket sheIl 44 which may advantageously be a larger size then the socket shell 12 shown in Figures 1, 3 and 5 to accommodate an additional number of connector pins is _ g _ llZ'77~4 provided adjacent to one side of the aforesaid pellet structures and surrounding the pins 30A, 30B.
A pair of additional electrical connector pins 46, 48 are located within the connector shell 24. The addi-s tional pins 46 and 48 are connected to a thermal compensator element 50 by separate wires 52 and 54, respectivelY~ whereby the thermal compensator element 50 is electrically connected across the additional pins 46 and 48. The thermal compensa-tor element 34 may be any suitable thermally responsive device, such devices being well-known in the art. Finally, an outer shell, or covering, of an electrically insulating ; potting compound 56 i5 provided to enclose the multi element structure and to space and to secure the pins 46 and 48, the element 50 and the pellets 2C and 2D while engaging the ; 15 connector shell 24. A first opening, or window, l9A is provided in the covering 56 to expose the cracked glass layer 10 of the reference electrode while a second opening l9B
is provided in the covering 40 to expose the ion responsive layer 40 of the ion responsive electrode structure.
In Figures 7 and 8 are end views of combined electrodes using the ~tructure of Figure 6 and showing various configura-tions for the windows l9A and l9B to accommodate desired operating and mechanical criteria for the combination electrode of Figure 6. Other configurations may be used by those skilled in the art without departing from the scope of the present invention.
In Figure 9, there is shown a pictorial illustration of a cross-section of an example of a multi-ion sensing electrode structure wherein a plurality of ion responsive electrodes are combined with a common reference electrode and a common thermal compensator. Thus, a first ion responsive electrode 60 using the previously discussed llZ~714 structure of either Figures 1 or 5 is provided with a first ion responsive outer layer, e.g., pH glass, while a second ion responsive electrode 62 using the previously discussed structure of either Figures 1 or 5 is provided with a second ion responsive outer layer, e.g., sodium ion selective glass. A shared, or common, reference electrode 64 and a thermal compensator 66 are also provided in the overall electrode structure. A socket shell 68 and thermal compensator connector pins 70, 72 are secured to the electrodes 60, 62, 64 by an electrically insulating and hermetic sealing envelope 74. A first window l9A for the cracked glass layer 40 of the reference electrode 64, a second window l9B for the first ion responsive electrode 60 and a third window l9C for the second ion responsive electrode 62 are provided in the hermetic envelope 74 by any suitable conventional technique. Figures 10 and 11 are end view of multi-ion electrode structures using the structure of Figure 9 and showing various configurations of the windows l9A, l9B and l9C. It should be noted that the structure shown in Figure 9 may be expanded to accommo-date more than two ion responsive electrode, more than one reference electrode and more than one thermal compensator, if desired.
MODE OF OPERATION
Since, in the RF sputtering process operation, the operating temperatures are below 200C, the preparation of the ion responsive electrode structure including the ion responsive layer is performed over a much smaller temperature range which further prevents the ion respon-s1~e 1ayer from cracking when it is cooled down to room temperature even if the ion responsive layer and the 112771~
electrolyte pellet do not have an exact temperature co-efficient match. Additionally, the thin, i.e., lO,000 A
maximum, ion responsive layer will stretch instead of cracking during temperature cycling to enable the electrode structure to withstand temperature cycling over a relatively wide temperature range, e.g., -70C to +200C even with a slight temperature coefficient mismatch. Inherently, the integrated electrode structure has a low im~edance due to the thinness of the outer ion responsive layer. An-other feature is an extreme ease of replacement whereby the ion responsive electrode, the reference electrode and the thermal compensator can be replaced as a single inexpensive unit. Further, since the delicate glass handling operations required for prior art electrodes have been eliminated, the high manufacturing repeatability of the product and the reduction of manufacturing rejects enhances the low manufacturing costs of either the separate electrodes shown in Figures l and 5 or the combinational electrode structure shown in Figures 5, 6 and 9. Finally, in addi-tion to savings in the amount of materials used for the thin layers of the multilayer structure, additional savings will be effected by the elimination of certain expensive metals which were necessary to previous blown glass electrodes because of the required glass-to-metal seals, e.g., platinum or other similar thermal property metals.
In order to enable the ion responsive electrode of the present invention either in a separate or combination embodiment to measure other than hydrogen ions, the ion responsive layer 40 would be changed to an appropriate ion responsive material. For example to measure fluoride llZ77~4 ion concentration, the layer 40 would be lanthanum fluoride.
Similarly, for potassium ions, potassium ion selective glass would be used, while for sodium ions, sodium ion selective glass would be used. The method of depositing the various materials for the ion responsive layer would be the same as that disclosed above for the pH electrode and the overall electrode structure would also be the same as that dis-closed for the pH electrode.
Accordingly, it may be seen that there has been provided, in accordance with the present invention, a solid state ion responsive and reference electrode structure having application in either a separate or a combination electrode construction.
Claims (44)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An ion responsive electrode comprising a solid electrolyte pellet, an electrical connection means in electrical contact with said pellet and an ion responsive layer on said pellet and spaced from said connection means.
2. An ion responsive electrode in accordance with claim 1 wherein said ion responsive layer is an RF sputtered layer.
3. An ion responsive electrode as set forth in claim 2 wherein said ion responsive layer has a coefficient of thermal expansion substantially matched to a coefficient of thermal expansion of said electrolyte pellet to minimize the differ-ential thermal expansion therebetween to maintain the integrity of said ion responsive layer.
4. An ion responsive electrode as set forth in claim 2 and further including encapsulating means encompassing said pellet and a portion of said ion responsive layer while exposing said connection means.
5. A pH electrode comprising a self-supporting electrolyte pellet, an electrical connection means in electrical contact with said pellet and a pH glass layer on said electrolyte pellet spaced from said connection means.
6. A pH electrode in accordance with claim 5 wherein said pH glass layer comprises an RF sputtered layer.
7. A pH electrode as set forth in claim 6 wherein said pH glass layer has a thickness of from 10 to 10,000 Angstroms.
8. A pH electrode as set forth in claim 6 wherein said pH glass layer has a coefficient of thermal expansion sub-stantially matched to a coefficient of thermal expansion of said electrolyte pellet to maintain the integrity of said pH
glass layer.
glass layer.
9. A pH electrode as set forth in claim 6 wherein said connection means includes a silver strip and said electrolyte pellet is silver chloride.
10. A pH electrode as set forth in claim 6 wherein said electrical connection means is partially embedded in said pellet.
11. A pH electrode as set forth in claim 6 and further including an encapsulating means covering and hermetically sealing said pellet and a portion of said pH glass layer while exposing said electrical connection means.
12. A combination electrode comprising an ion responsive electrode, said ion responsive electrode including a solid electrolyte pellet, an electrical connection means in electrical contact with said pellet and an ion responsive layer on said pellet and spaced from said con-nection means;
a second solid electrolyte pellet, second electrical connection means to said second pellet, a cracked glass layer on said second electrolyte pellet spaced from said second connection means, said cracked glass layer having a coefficient of thermal expansion mismatched with respect to said second electrolyte pellet to produce dif-ferentlal expansion therebetween, and encapsulating means for covering and spacing said first and second pellets and a portion of said pH glass layer and said cracked glass layers while exposing said first and second connection means.
a second solid electrolyte pellet, second electrical connection means to said second pellet, a cracked glass layer on said second electrolyte pellet spaced from said second connection means, said cracked glass layer having a coefficient of thermal expansion mismatched with respect to said second electrolyte pellet to produce dif-ferentlal expansion therebetween, and encapsulating means for covering and spacing said first and second pellets and a portion of said pH glass layer and said cracked glass layers while exposing said first and second connection means.
13. A combination electrode as set forth in claim 12 wherein said first and second electrolyte pellets are silver chloride and said first and second connection means each include a silver strip.
14. A combination electrode as set forth in claim 12 wherein said pH glass layer is an RF sputtered glass layer.
15. A combination electrode as set forth in claim 12 and including a thermal compensating means mounted thermal associa-tion with said encapsulating means while being electrically isolated from said first and second electrolyte pellets and said pH and cracked glass layers.
16. A combination electrode as set forth in claim 15 and further including third electrical connection means connected to said thermal compensating means.
17. A combination electrode as set forth in claim 12 wherein said pH glass layer and said cracked glass layer are each an RF sputtered glass layer.
18. A combination electrode comprising an ion responsive electrode, said ion responsive electrode including a solid electrolyte pellet, an electrical connection means in electrical contact with said pellet and an ion responsive layer on said pellet and spaced from said con-nection means;
a second solid electrolyte pellet an ion conducting path layer on said second electro-lyte pellet and encapsulating means for supporting said first and second pellets in electrical isolation and for covering said first and second pellets while exposing a portion of said pH
glass layer and said ion conducting path layer.
a second solid electrolyte pellet an ion conducting path layer on said second electro-lyte pellet and encapsulating means for supporting said first and second pellets in electrical isolation and for covering said first and second pellets while exposing a portion of said pH
glass layer and said ion conducting path layer.
19. A combination electrode as set forth in claim 18 and further including first electrical connection means connected to said first pellet and second electrical connection means connected to said second pellet, said encapsulating means exposing said first and second connection means.
20. A combination electrode comprising an ion responsive electrode, said ion responsive electrode including a solid electrolyte pellet, an electrical connection means in electrical contact with said pellet and an ion responsive layer on said pellet and spaced from said con-nection means;
a second solid electrolyte pellet, a cracked glass layer on said second electrolyte pellet, said cracked glass layer having a coefficient of thermal expansion mismatched with respect to said second electrolyte pellet to produce differential expansion therebetween to induce cracking of said cracked glass layer, and encapsulating means for supporting and spacing said first and second pellets in electrical isolation and for cover-ing said first and second pellets while exposing a portion of said ion responsive layer and said cracked glass layer.
a second solid electrolyte pellet, a cracked glass layer on said second electrolyte pellet, said cracked glass layer having a coefficient of thermal expansion mismatched with respect to said second electrolyte pellet to produce differential expansion therebetween to induce cracking of said cracked glass layer, and encapsulating means for supporting and spacing said first and second pellets in electrical isolation and for cover-ing said first and second pellets while exposing a portion of said ion responsive layer and said cracked glass layer.
21. A combination electrode as set forth in claim 20 wherein said ion responsive layer is an RF sputtered layer.
22. A combination electrode as set forth in claim 20 and further including first electrical connection means connected to said first pellet and spaced from said ion responsive layer and second electrical connection means connected to said second pellet and spaced from said cracked glass layer, said encap-sulating means exposing said first and second connection means.
23. A combination electrode as set forth in claim 20 wherein said ion responsive layer and said cracked glass layer are each an RF sputtered layer.
24. A combination electrode comprising an ion responsive electrode, said ion responsive electrode including a solid electrolyte pellet, an electrical connection means in electrical contact with said pellet and an ion responsive layer on said pellet and spaced from said con-nection means;
a second solid electrolyte pellet, an ion conducting path layer on said second electro-lyte pellet, and encapsulating means for supporting and spacing said first and second pellets in electrical isolation and for covering said first and second pellets while exposing a portion of said ion responsive layer and said ion conducting path layer.
a second solid electrolyte pellet, an ion conducting path layer on said second electro-lyte pellet, and encapsulating means for supporting and spacing said first and second pellets in electrical isolation and for covering said first and second pellets while exposing a portion of said ion responsive layer and said ion conducting path layer.
25. A combination electrode as set forth in claim 24 and further including first electrical connection means connected to said first pellet and spaced from said ion responsive layer and second electrical connection means connected to said second pellet and spaced from said ion conducting path layer, said encapsulating means exposing said first and second connection means.
26. A combination electrode as set forth in claim 24 wherein said ion responsive layer and said ion conducting path layer are each an RF sputtered layer.
27. A method of making an ion responsive electrode com-prising the steps of forming a solid electrolyte pellet and depositing an ion responsive layer on said electrolyte pellet, said ion responsive layer having a coefficient of thermal ex-pansion substantially matched with respect to a coefficient of thermal expansion of said electrolyte pellet to maintain the integrity of said ion responsive layer.
28. A method of making an ion responsive electrode as set forth in claim 27 wherein said ion responsive layer is deposited by RF sputtering.
29. A method of making an ion responsive electrode as set forth in claim 28 including the further step of providing an electrical connection to said electrolyte pellet.
30. A method of making an ion responsive electrode as set forth in claim 29 and including the further step of encapsulat-ing said pellet while exposing a portion of said ion responsive layer and said electrical connection.
31. A method of making an ion responsive electrode as set forth in claim 29 wherein said forming of said electrolyte pellet includes the step of compressing an electrolyte powder and said step of providing an electrical connection includes the step of supporting an electrical connector partially embedded in said electrolyte powder during said compression.
32. A method of making a pH electrode comprising the steps of forming a solid electrolyte pellet and depositing a pH glass layer by RF sputtering on said electrolyte pellet, said glass layer having a coefficient of thermal expansion substantially matched with respect to a coefficient of thermal expansion of said electrolyte layer to maintain the integrity of said glass layer.
33. A method of making a pH electrode as set forth in claim 32 and including the further step of providing an elec-trical connection to said electrolyte pellet.
34. A method of making a pH electrode as set forth in claim 33 and including the further step of encapsulating said pellet while exposing a portion of said pH glass layer and said electrical connection.
35. A method of making a combination electrode comprising the steps of forming a first solid electrolyte pellet, deposit-ing a pH glass layer on said solid electrolyte pellet, said glass layer having a coefficient of thermal expansion substan-tially matched to a coefficient of thermal expansion of said pellet to maintain the integrity of said glass layer, forming a second solid electrolyte pellet, depositing a second glass layer on said electrolyte pellet, said second glass layer having a coefficient of thermal expansion mismatched with respect to a coefficient of thermal expansion of said second electrolyte pellet to produce differential expansion therebetween causing cracking of said second glass layer during a predetermined temperature cycle, encapsulating said first and second pellets in a spaced apart electrically isolated relationship while exposing a portion of said pH glass layer and said second glass layer and exposing said electrode to said temperature cycle.
36. A method of making a combination electrode as set forth in claim 35 wherein said pH glass layer and said second glass layer are deposited by RF sputtering.
37. A method of making a combination electrode as set forth in claim 35 including the further step of providing separate electrical connections for said first and second pellets, said encapsulating exposing said electrical connections.
38. A method of making a combination electrode as set forth in claim 35 including the further step of providing a thermal compensating means electrically isolated from said first and second pellets and encapsulated with said first and second pellets.
39. A method of making a combination electrode as set forth in claim 38 and including the further steps of providing an electrical connection for said thermal compensating means, said encapsulating exposing said electrical connection for said thermal compensating means.
40. A method of making a combination electrode comprising the steps of forming a first solid electrolyte pellet, deposit-ing an ion responsive layer on said electrolyte pellet, forming a second electrolyte pellet, depositing an ion conducting path layer on said second electrolyte pellet and encapsulating said first and second pellets in a spaced apart electrically isolated relationship while exposing a portion of said ion responsive layer and said ion conducting path layer.
41. A method of making a combination electrode as set forth in claim 39 wherein said ion responsive layer and said ion conducting path layer are each deposited by RF sputtering.
42. A method of making a combination electrode as set forth in claim 40 and including the further steps of providing separate electrical connections for said first and second electrolyte pellets, said encapsulation exposing said electrical connections.
43. A method of making a combination electrode as set forth in claim 41 including the further step of supporting a thermal compensating means electrically isolated from said first and second electrolyte pellets and encapsulated therewith.
44. A method of making a combination electrode as set forth in claim 42 including the further step of providing electrical connection for said thermal compensating means, said encapsulation exposing said electrical connection for said thermal compensating means.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000386634A CA1135790A (en) | 1978-03-06 | 1981-09-24 | Method of making and structure for a solid state ion responsive and reference electrodes |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US88380778A | 1978-03-06 | 1978-03-06 | |
| US883,807 | 1978-03-06 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1127714A true CA1127714A (en) | 1982-07-13 |
Family
ID=25383370
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA317,921A Expired CA1127714A (en) | 1978-03-06 | 1978-12-14 | Method of making and structure for a solid state ion responsive and reference electrodes |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1127714A (en) |
| GB (1) | GB2015742B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH661799A5 (en) * | 1983-06-21 | 1987-08-14 | Proton Ag | TEMPERATURE-INDEPENDENT RADIO MEASURING CHAIN FOR POTENTIOMETRIC MEASUREMENTS. |
| DE102014105575A1 (en) * | 2014-04-17 | 2015-10-22 | Innovative Sensor Technology Ist Ag | Process for the preparation of a pH half cell and a pH half cell |
-
1978
- 1978-12-14 CA CA317,921A patent/CA1127714A/en not_active Expired
-
1979
- 1979-02-14 GB GB7905162A patent/GB2015742B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB2015742B (en) | 1982-08-25 |
| GB2015742A (en) | 1979-09-12 |
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