WO2011049427A1 - Method of fabricating integrated reference electrode - Google Patents
Method of fabricating integrated reference electrode Download PDFInfo
- Publication number
- WO2011049427A1 WO2011049427A1 PCT/MY2009/000189 MY2009000189W WO2011049427A1 WO 2011049427 A1 WO2011049427 A1 WO 2011049427A1 MY 2009000189 W MY2009000189 W MY 2009000189W WO 2011049427 A1 WO2011049427 A1 WO 2011049427A1
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- WO
- WIPO (PCT)
- Prior art keywords
- reference electrode
- glass
- glass wafer
- cavities
- cavity
- Prior art date
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Classifications
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- 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
- G01N27/301—Reference electrodes
Definitions
- the present invention relates generally to integrated chemical sensors, more particularly to a reference electrode of liquid junction type.
- Chemical sensors can be built in a miniaturized platform.
- Integrated miniature sensor such as Ion Selective Electrode (ISE) or potentionstat-based with Liquid Junction Reference Electrode (LJRE) are common in miniaturized platform to measure chemical properties of electrolytes such as pH, sodium, and potassium.
- ISE Ion Selective Electrode
- LJRE Liquid Junction Reference Electrode
- a true solid state reference electrode would comprise a material whose interfacial potential remains invariant for different electrolytes and varying concentrations of aqueous electrolyte.
- the interfacial potential is limited by interfacial exchange currents.
- LJRE provides both electrical connection and a liquid junction between a reference liquid solution and a solution to be tested.
- Conventional LJRE has a relatively small volume of reference solution.
- a thin film Ag/AgCI electrode is used.
- the electrode is covered with test solution of constant CI " concentration or the Ag/AgCI is covered with a polymer saturated with a solution of CI " .
- a means is provided for applying fixed control voltage to reference liquid solution.
- Metal based sensors such as ISE require reference electrode to make measurements.
- both sensors and reference electrode are created separately, combined and then tested. The whole process is costly and time consuming.
- the production of LJRE also involves tedious steps of producing separate parts and electrodes.
- the LJRE also suffers from high leakage which contributes to low performance.
- An improved LJRE is proposed to improve manufacturability thru low cost batch process of silicon glass wafer while providing excellent sensor protection.
- a batch processing method based on glass wafer using integrated circuit manufacturing process can reduce the cost while providing integrated test method utilizing integrated circuit tester.
- the proposed invention proposes an improved method of fabricating reference electrode. Part of the reference electrode is fabricated, comprising:
- the novelty of the invention lays in the channel between two cavities and a layer of grass frit over the cavities and channel mouth.
- the glass frit used is preferably a relatively high porosity glass frit.
- the glass wafer is further processed to etch off glass frit in one of the cavities to form a reference electrode cavity.
- the glass wafer is etched to create holes thru the cavities.
- a second glass wafer is prepared with two layers of silver on different parts of glass wafer, said silver is to receive and complement holes created.
- a layer of relatively low porosity grass frit is deposited on top of second glass wafer and silver layer.
- a reference electrode providing both electrical connection and a liquid junction between a reference electrolyte and a solution to be tested comprising: a glass wafer provided with a cavity to hold reference electrolyte and another cavity to hold test solution; silver electrodes; and a cap on the reference electrode cavity; characterized in that; the wafer is shaped to form a channel that connects both cavities and a membrane of glass frit is placed between the test solution cavity and the channel.
- Fig. 1 shows a sectional view of a glass wafer with a pair of cavities
- Fig. 2 shows a sectional view of the glass wafer having a channel to connect the cavities
- Fig. 3 shows a sectional view of etched glass wafer with a layer of glass frit
- Fig. 4 shows a sectional view of etched glass frit off one of the cavity
- Fig. 5 shows a sectional view of holes formed thru the cavities
- Fig. 6 shows a sectional view of a second glass wafer with patterned silver
- Fig. 7 shows a sectional view of the second glass wafer of Fig. 6 with glass frit
- Fig. 8 shows a sectional view of glass wafer of Fig. 5 bonded with glass wafer of Fig. 7;
- Fig. 9 shows a sectional view of glass wafer of Fig. 8 filled with electrolyte and electrode solution.
- the present invention proposes an improved integrated reference electrode. It takes two glass wafers and five masking steps to fabricate a complete LJRE.
- a glass based integrated sensor is a batch manufacturing process similar as integrated circuit fabrication. The process can be well controlled and test can also be integrated and executed using a typical integrated circuit tester. Firstly, a glass wafer 20 is patterned and etched on a first side to create a pair of cavities 22, as shown in Fig. 1. The cavities can have similar size or shape. This step is facilitated by a first mask. Next, the glass wafer is patterned and etched with the aid of a second mask to create a channel 24 to link the cavities 22, as shown in Fig. 2. The channel is preferably created on a second side.
- a layer of glass frit 26 is deposited on the second side of glass wafer, as shown in Fig. 3.
- the glass frit is preferably a relatively high porosity glass frit.
- the channel 24 forms a channel that connects both cavities are novel features of the invention.
- Reference electrode cavity Glass frit 26 in one of the cavities is etched to connect the cavity 22 with the channel 24, as shown in Fig. 4.
- a third mask is used for this process.
- a layer is etched off the second side of glass wafer to create holes 22A thru the cavities, as shown in Fig. 5. Note that a membrane of glass frit 26A is sandwiched between a cavity and channel. This cavity is formed to be filled with test solution.
- a second glass wafer 30 is provided with two layers of silver 32 on different parts of glass wafer, as shown in Fig. 6.
- the silver is patterned to receive and complement holes formed in former glass wafer with a fourth mask.
- a layer of relatively low porosity glass frit 34 is deposited on top of second glass wafer and silver layer.
- the grass frit is patterned and etched to expose part of silver, for each silver, as shown, in Fig. 7.
- the first side of glass wafer with cavities 20 is bonded on top of the grass fit of second glass wafer 30, aligning the holes 22A on the silver 32, as shown in Fig. 8. It is important to align the holes on top of the silver so that it the holes can facilitate solution to the silver which acts as electrodes.
- a reference electrode cavity 22B is connected to a channel 24, and a glass frit separates the channel from test solution cavity 22C.
- the reference electrode cavity 22B is filled with reference electrolyte 36, as shown in Fig. 9.
- The, the reference electrode cavity 22B is filled with compatible reference electrode solution 38.
- Electrolyte such as FeCI is used for electrolysis of Ag into AgCI.
- a compatible reference electrode solution 38 is any solution compatible with electrolyte such as KCI. Later, the reference electrode cavity is capped with silicone gel 38.
- the above mentioned steps provide a complete LJRE solution.
- the LJRE provides both electrical connection and a liquid junction between the reference electrolyte and a solution to be tested.
- the LJRE comprises a glass wafer 20, silver electrodes 32 and a cap 38.
- the glass wafer is provided with a cavity 22B to hold reference electrolyte and another cavity 22C to hold test solution.
- the cap is used to cover the reference electrode cavity.
- the LJRE is characterized in that the wafer is shaped to form a channel 24 that connects both cavities and a membrane of glass frit 26A is placed between the test solution cavity and the channel.
- the glass frit used is preferably a relatively high porosity glass frit. Accordingly, the invention disclosed a method to fabricate integrated reference electrode. It is the combination of the above features and its technical advantages give rise to the uniqueness of such invention. Although the descriptions above contain much specificity, these should not be construed as limiting the scope of the embodiment but as merely providing illustrations of some of the presently preferred embodiments.
Abstract
The proposed invention proposes an improved method of fabricating reference electrode. Part of the reference electrode is fabricated, comprising: patterning and etching a first side of a glass wafer (20) to create a pair of cavities (22); characterized in that; patterning and etching a side of glass wafer to create a channel (24) to link the cavities; and depositing a layer of glass frit (26) on the second side of the glass wafer. The novelty of the invention lays in the channel (24) between two cavities and a layer of grass frit (26) the cavities. The glass frit used is preferably a relatively high porosity glass frit. Hence, an integrated reference electrode is characterized in that; the wafer is shaped to form a channel (24) that connects both cavities and a membrane of glass frit (26A) is placed between the test solution cavity and the channel.
Description
METHOD OF FABRICATING INTEGRATED REFERECE ELECTRODE
The present invention relates generally to integrated chemical sensors, more particularly to a reference electrode of liquid junction type.
BACKGROUND OF THE INVENTION
Chemical sensors can be built in a miniaturized platform. Integrated miniature sensor such as Ion Selective Electrode (ISE) or potentionstat-based with Liquid Junction Reference Electrode (LJRE) are common in miniaturized platform to measure chemical properties of electrolytes such as pH, sodium, and potassium.
A true solid state reference electrode would comprise a material whose interfacial potential remains invariant for different electrolytes and varying concentrations of aqueous electrolyte. The interfacial potential is limited by interfacial exchange currents.
LJRE provides both electrical connection and a liquid junction between a reference liquid solution and a solution to be tested. Conventional LJRE has a relatively small volume of reference solution. A thin film Ag/AgCI electrode is used. The electrode is covered with test solution of constant CI" concentration or the Ag/AgCI is covered with a polymer saturated with a solution of CI". A means is provided for applying fixed control voltage to reference liquid solution. Metal based sensors such as ISE require reference electrode to make measurements. Currently, both sensors and reference electrode are created separately, combined and then tested. The whole process is costly and time consuming. The production of LJRE also involves tedious steps of producing separate parts and electrodes. The LJRE also suffers from high leakage which contributes to low performance.
An improved LJRE is proposed to improve manufacturability thru low cost batch process of silicon glass wafer while providing excellent sensor protection. A batch processing method based on glass wafer using integrated circuit manufacturing process can reduce the cost while providing integrated test method utilizing integrated circuit tester.
SUMMARY OF THE INVENTION
The proposed invention proposes an improved method of fabricating reference electrode. Part of the reference electrode is fabricated, comprising:
patterning and etching a first side of a glass wafer to create a pair of cavities; characterized in that;
patterning and etching a side of glass wafer to create a channel to link the cavities; and
depositing a layer of glass frit on the second side of the glass wafer.
The novelty of the invention lays in the channel between two cavities and a layer of grass frit over the cavities and channel mouth. The glass frit used is preferably a relatively high porosity glass frit. The glass wafer is further processed to etch off glass frit in one of the cavities to form a reference electrode cavity. The glass wafer is etched to create holes thru the cavities.
A second glass wafer is prepared with two layers of silver on different parts of glass wafer, said silver is to receive and complement holes created. A layer of relatively low porosity grass frit is deposited on top of second glass wafer and silver layer. By patterning and etching the grass frit to expose a part of silver, for each silver; bonding the glass wafer with cavities on top of the grass frit, aligning the holes on the silver; filling the reference electrode cavity with reference electrolyte; filling the reference electrode cavity with compatible reference electrode solution; and capping the reference electrode cavity with silicone gel; creates a complete LJRE.
Hence, a reference electrode providing both electrical connection and a liquid junction between a reference electrolyte and a solution to be tested comprising: a glass wafer provided with a cavity to hold reference electrolyte and another cavity to hold test solution; silver electrodes; and a cap on the reference electrode cavity; characterized in that; the wafer is shaped to form a channel that connects both cavities and a membrane of glass frit is placed between the test solution cavity and the channel.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in greater detail, by way of an example, with reference to the accompanying drawings, in which:
Fig. 1 shows a sectional view of a glass wafer with a pair of cavities;
Fig. 2 shows a sectional view of the glass wafer having a channel to connect the cavities;
Fig. 3 shows a sectional view of etched glass wafer with a layer of glass frit; Fig. 4 shows a sectional view of etched glass frit off one of the cavity; Fig. 5 shows a sectional view of holes formed thru the cavities;
Fig. 6 shows a sectional view of a second glass wafer with patterned silver; Fig. 7 shows a sectional view of the second glass wafer of Fig. 6 with glass frit;
Fig. 8 shows a sectional view of glass wafer of Fig. 5 bonded with glass wafer of Fig. 7; and
Fig. 9 shows a sectional view of glass wafer of Fig. 8 filled with electrolyte and electrode solution.
DETAILED DESCRIPTION OF THE PREFFERED EMBODIMENT
The present invention proposes an improved integrated reference electrode. It takes two glass wafers and five masking steps to fabricate a complete LJRE. A glass based integrated sensor is a batch manufacturing process similar as integrated circuit fabrication. The process can be well controlled and test can also be integrated and executed using a typical integrated circuit tester. Firstly, a glass wafer 20 is patterned and etched on a first side to create a pair of cavities 22, as shown in Fig. 1. The cavities can have similar size or shape. This step is facilitated by a first mask.
Next, the glass wafer is patterned and etched with the aid of a second mask to create a channel 24 to link the cavities 22, as shown in Fig. 2. The channel is preferably created on a second side. Next, a layer of glass frit 26 is deposited on the second side of glass wafer, as shown in Fig. 3. The glass frit is preferably a relatively high porosity glass frit. The channel 24 forms a channel that connects both cavities are novel features of the invention.
Now, the creation of reference electrode cavity will be described. Glass frit 26 in one of the cavities is etched to connect the cavity 22 with the channel 24, as shown in Fig. 4. A third mask is used for this process.
Next, a layer is etched off the second side of glass wafer to create holes 22A thru the cavities, as shown in Fig. 5. Note that a membrane of glass frit 26A is sandwiched between a cavity and channel. This cavity is formed to be filled with test solution.
A second glass wafer 30 is provided with two layers of silver 32 on different parts of glass wafer, as shown in Fig. 6. The silver is patterned to receive and complement holes formed in former glass wafer with a fourth mask. Next, a layer of relatively low porosity glass frit 34 is deposited on top of second glass wafer and silver layer. The grass frit is patterned and etched to expose part of silver, for each silver, as shown, in Fig. 7.
The first side of glass wafer with cavities 20 is bonded on top of the grass fit of second glass wafer 30, aligning the holes 22A on the silver 32, as shown in Fig. 8. It is important to align the holes on top of the silver so that it the holes can facilitate solution to the silver which acts as electrodes. Here, it can be clearly seen that there are two cavities. A reference electrode cavity 22B is connected to a channel 24, and a glass frit separates the channel from test solution cavity 22C. The reference electrode cavity 22B is filled with reference electrolyte 36, as shown in Fig. 9. The, the reference electrode cavity 22B is filled with compatible reference electrode solution 38. Electrolyte such as FeCI is used for electrolysis of Ag into AgCI. A compatible reference electrode solution 38 is any solution compatible with electrolyte such as KCI. Later, the reference electrode cavity is capped with silicone gel 38.
The above mentioned steps provide a complete LJRE solution. The LJRE provides both electrical connection and a liquid junction between the reference electrolyte and a solution to be tested. The LJRE comprises a glass wafer 20, silver electrodes 32 and a cap 38. The glass wafer is provided with a cavity 22B to hold reference electrolyte and another cavity 22C to hold test solution. The cap is used to cover the reference electrode cavity. The LJRE is characterized in that the wafer is shaped to form a channel 24 that connects both cavities and a membrane of glass frit 26A is placed between the test solution cavity and the channel. The glass frit used is preferably a relatively high porosity glass frit. Accordingly, the invention disclosed a method to fabricate integrated reference electrode. It is the combination of the above features and its technical advantages give rise to the uniqueness of such invention. Although the descriptions above contain much specificity, these should not be construed as limiting the scope of the embodiment but as merely providing illustrations of some of the presently preferred embodiments.
Claims
1. A method of fabricating integrated reference electrode, comprising:
patterning and etching a first side of a glass wafer (20) to create a pair of cavities (22);
characterized in that;
patterning and etching a side of glass wafer to create a channel (24) to link the cavities; and
depositing a layer of glass frit (26) on the second side of the glass wafer.
2. A method of claim 1, wherein the channel (24) is created on the second side of the glass wafer (20).
3. A method of claim 1 , wherein the grass frit is preferably a relatively high porosity glass frit (26).
4. A method according to claim 1 , further comprising, etching off glass frit in one of the cavities to connect the cavity (22) with the channel (24), to form a reference electrode cavity (22B).
5. A method according to claim 4, further comprising, etching a layer off the second side of glass wafer to create holes (22A) thru cavities.
6. A method according to claim 5, further comprising:
providing a second glass wafer (30) with two layers of silver (32) on different parts of glass wafer, said silver is to receive and complement holes (22A) formed in former glass wafer (20);
depositing a layer of relatively low porosity glass frit (32) on top of second glass wafer and silver layer; and
patterning and etching the grass frit to expose a part of silver, for each silver; bonding the fist side of glass wafer of claim 5 (20) on top of the grass frit of second glass wafer (30), aligning the holes on the silver.
7. A method according to claim 6, further comprising:
filling the reference electrode cavity (22B) with reference electrolyte;
filling the reference electrode cavity (22B) with compatible reference electrode solution; and capping the reference electrode cavity.
8. A method according to claim 6, wherein the reference electrode cavity is capped with silicone gel (38).
9. An integrated reference electrode providing both electrical connection and a liquid junction between a reference electrolyte and a solution to be tested comprising:
a glass wafer provided with a cavity (22B) to hold reference electrolyte and another cavity (22C) to hold test solution;
silver electrodes (32) ; and
a cap on the reference electrode cavity (38);
characterized in that;
the wafer is shaped to form a channel (24) that connects both cavities and a membrane of glass frit (26A) is placed between the test solution cavity and the channel.
10. An integrated reference electrode according to claim 9, wherein the glass frit (26A) is preferably a relatively high porosity glass frit.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| MYPI20097021 MY150721A (en) | 2009-10-24 | 2009-10-24 | Method of fabricating integrated reference electrode |
| MYPI20097021 | 2009-10-24 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2011049427A1 true WO2011049427A1 (en) | 2011-04-28 |
Family
ID=43900497
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/MY2009/000189 WO2011049427A1 (en) | 2009-10-24 | 2009-11-11 | Method of fabricating integrated reference electrode |
Country Status (2)
| Country | Link |
|---|---|
| MY (1) | MY150721A (en) |
| WO (1) | WO2011049427A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3088879A1 (en) * | 2015-04-30 | 2016-11-02 | Stichting IMEC Nederland | A reference electrode with a pore membrane |
| CN108459061A (en) * | 2017-11-29 | 2018-08-28 | 宁波大学 | A kind of silver/silver chloride reference electrode and preparation method thereof |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4786396A (en) * | 1987-06-26 | 1988-11-22 | The Washington Technology Center | Ion electrode and method of making it |
| US4874499A (en) * | 1988-05-23 | 1989-10-17 | Massachusetts Institute Of Technology | Electrochemical microsensors and method of making such sensors |
| US4874500A (en) * | 1987-07-15 | 1989-10-17 | Sri International | Microelectrochemical sensor and sensor array |
| KR960010690B1 (en) * | 1990-12-06 | 1996-08-07 | 후지쓰 가부시끼가이샤 | Small glass electrode and process for preparation thereof |
| US20070138027A1 (en) * | 2005-12-15 | 2007-06-21 | Medtronic, Inc. | Monolithic electrodes and pH transducers |
-
2009
- 2009-10-24 MY MYPI20097021 patent/MY150721A/en unknown
- 2009-11-11 WO PCT/MY2009/000189 patent/WO2011049427A1/en active Application Filing
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4786396A (en) * | 1987-06-26 | 1988-11-22 | The Washington Technology Center | Ion electrode and method of making it |
| US4874500A (en) * | 1987-07-15 | 1989-10-17 | Sri International | Microelectrochemical sensor and sensor array |
| US4874499A (en) * | 1988-05-23 | 1989-10-17 | Massachusetts Institute Of Technology | Electrochemical microsensors and method of making such sensors |
| KR960010690B1 (en) * | 1990-12-06 | 1996-08-07 | 후지쓰 가부시끼가이샤 | Small glass electrode and process for preparation thereof |
| US20070138027A1 (en) * | 2005-12-15 | 2007-06-21 | Medtronic, Inc. | Monolithic electrodes and pH transducers |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3088879A1 (en) * | 2015-04-30 | 2016-11-02 | Stichting IMEC Nederland | A reference electrode with a pore membrane |
| CN108459061A (en) * | 2017-11-29 | 2018-08-28 | 宁波大学 | A kind of silver/silver chloride reference electrode and preparation method thereof |
| CN108459061B (en) * | 2017-11-29 | 2020-04-10 | 宁波大学 | Silver/silver chloride reference electrode and manufacturing method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| MY150721A (en) | 2014-02-28 |
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