CA1077566A - Polarographic membrane apparatus - Google Patents
Polarographic membrane apparatusInfo
- Publication number
- CA1077566A CA1077566A CA266,637A CA266637A CA1077566A CA 1077566 A CA1077566 A CA 1077566A CA 266637 A CA266637 A CA 266637A CA 1077566 A CA1077566 A CA 1077566A
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- Prior art keywords
- membrane
- convex surface
- assembly
- polarographic
- cathode
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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
- G01N27/327—Biochemical electrodes, e.g. electrical or mechanical details for in vitro measurements
- G01N27/3271—Amperometric enzyme electrodes for analytes in body fluids, e.g. glucose in blood
-
- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
- C12Q1/00—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions
- C12Q1/001—Enzyme electrodes
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- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Organic Chemistry (AREA)
- Zoology (AREA)
- Proteomics, Peptides & Aminoacids (AREA)
- Wood Science & Technology (AREA)
- Physics & Mathematics (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Molecular Biology (AREA)
- Immunology (AREA)
- Engineering & Computer Science (AREA)
- Biotechnology (AREA)
- Hematology (AREA)
- Pathology (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Microbiology (AREA)
- General Physics & Mathematics (AREA)
- Electrochemistry (AREA)
- Biophysics (AREA)
- Bioinformatics & Cheminformatics (AREA)
- General Engineering & Computer Science (AREA)
- Genetics & Genomics (AREA)
- Investigating Or Analysing Biological Materials (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
- Measuring Or Testing Involving Enzymes Or Micro-Organisms (AREA)
- Apparatus Associated With Microorganisms And Enzymes (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
An improved apparatus, such as a polarographic elec-trode apparatus, is described wherein a semi-permeable membrane is supported against a convex surface and wherein the likeli-hood of damage to such membrane during mounting and use is minimized. In the apparatus the membrane is stretched over the convex surface of a first member in a manner allowing, during assembly of the apparatus, any fluid located between the mem-brane and the convex surface to escape therefrom around the edges of the membrane. The membrane is clamped between the convex surface of said first member and a complemental concave surface of a second member such that the membrane is held in stretched relationship against and in close contact with the convex surface. A gasket is also included to form a fluid-tight seal between said membrane and said second member.
An improved apparatus, such as a polarographic elec-trode apparatus, is described wherein a semi-permeable membrane is supported against a convex surface and wherein the likeli-hood of damage to such membrane during mounting and use is minimized. In the apparatus the membrane is stretched over the convex surface of a first member in a manner allowing, during assembly of the apparatus, any fluid located between the mem-brane and the convex surface to escape therefrom around the edges of the membrane. The membrane is clamped between the convex surface of said first member and a complemental concave surface of a second member such that the membrane is held in stretched relationship against and in close contact with the convex surface. A gasket is also included to form a fluid-tight seal between said membrane and said second member.
Description
~77566 BACKGROUND AND PRIOR ART
.
Apparatus employing semi-permeable membranes are ,,~ !
employed for various purposes. They are used, for example, in reverse osmosis processes to,separate components of a fluid mixture. They are also used in electrode apparatus for the detection and measurement of specific components in a fluid mixture.
One apparatus, for example, previously suggested for the detection and measurement of glucose in body fluids, such as blood, consisted of a sample chamber into which samples were introduced in discrete individual amounts. One : side of a semi-permeable membrane containing glucose oxidase was in communication with,the sample chamber and was capable of allowing portions of the sample in the chamber to pass therethrough. During this passage the glucose oxidase in the membrane catalyzed the oxidation of the glucose in the presence of oxygen in the sample to form hydrogen peroxide. A polarographic anode-cathoae assembly was posi-tioned in close proximity to the other side of the membrane and was capable of measuring the amount of hydrogen peroxide ~-formed, thus detecting and measuring the amount of glucose;n the sample.
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~77S~;6 1 This prior art apparatus had several disadvantages.
First, when attempts were made to miniaturize the apparatus, the means for mounting the membrane against the polaro-graphic electrode assembly often caused undesirable rupture of the membrane during mounting or subsequent use. Second, there was often an undesirable slowness in electrode re-sponse due to variations in membrane mounting and due to fluids, such as gases, being trapped between the membrane and the electrode assembly. The prior art apparatus was also not capable of handling continuous sampling conditions.
These and other disadvantages of the prior art mem-brane apparatus are overcome by the apparatus of the pre-sent invention.
SUMMARY OF T~IF INVF.NTION
In accordance with the present invention, apparatus is provided wherein a membrane is supported in close contact with a surface, said apparatus comprising a first member having a convex surface, a second member having a concave surface facing and complemental to said convex surface, a membrane interposed between said complemental suraces, and means cooperable with said first and second members for effecting clamping engagement of said membrane between said complemental surfaces whereby said membrane is stretch-ed over and in close contact with said convex surfaceO
During the assembly of this apparatus any fluid located between the membrane and the convex surface is allowed to escape therefrom around the edges of the membrane.
~17~
Figure 1 is a vertical cross-sectional view of one illustrative embodiment of apparatus of the present in-vention employing an electrode assembly with ancillary circuits shown schematically in block diagram form;
Figure 2 is an end view of the sample chamber member of the apparatus of Figure l;
Figure 3 is a vertical cross-sectional view of a por-tion of the apparatus of Figure 1 illustrating one step in the mounting of a membrane used with such apparatus;
Figure ~ is a view similar to that of Figure 3 lllustrat;ng a ~urther step in the mounting of l;hc membrane;
and Figure 5 is an enlarged fragmentary vertical cross -sectional view of a semi-permeable membrane useful in the apparatus of the present invention.
DESCRIPTION OF THE INVENTION
Referring to Figure 1, the apparatus 10 represents an illustrative embodiment of one form of the novel ap-paratus useful for sensing glucose in a sample fluid. Ithas a hydrogen peroxide detecting polarographic anode -cathode assembly comprising a central cylindrical anode 11 and a surrounding annular cathode 12 encased in a general-ly cylindrical insulating first or membrane support member 13. The anode is conveniently formed from platinum and the cathode is conveniently formed from silver. However, other electrically conductive anode and cathode materials can be ~ ~ 7 ~
1 used. The first member 13 is conveniently formed of an organoplastic material, such as epoxy resin, and is enclosed within a generally cup-shaped electrically conductive case member 14 which is preferably formed of stainless steel.
Case member 14 is formed in its end face with diametrically oppositely disposed parallel bores 15 and 16 and is also formed with external threads 17. Electrical conductors 18 and 19 extend from the anode 11 and cathode 12, respectively, through first member 13 and through suitable openings in case member 14. Conductor 18 is preferably insulated by spacing from the case 14, as shown, whereas conductor 19 is preferably in circuit therewith. The upper suraces 20 and 21 of anode 11 and cathode 12, resp~ct:ively, are co-incident with and orm part o~ a ~enerally convex surface 8 which constitutes the b~ttom wall of a generally cyl~ndri-cal recess 9 formed in the upper surface of support member 13. Recess 9 has cylindrical sidewall portion 28 therein.
A circular semi-permeable membrane 22 overlays the convex surface 8, including surfaces 20 and 21~ An annular gasket, such as an O-ring 27, is placed on the peripheral edge portions of membrane 22 within the recess 9 as shown. It is covenient to employ a membrane unit in which the O-ring 27 is attached to the membrane 22.
A generally cylindrical second sample chamber or mem-brane positioning member 29 of smaller diameter than the cylindrical sidewall 28 and having a concave lower end surface 31 facing and complemental to convex surface 8 is positio~ned on membrane 22 coaxially within the recess 9 and O-ring 27 The concave lower end surface 31 is formed with recess means which may take the form of a groove de-fining a sample flow passage 32 having a straight diametrically 1~77566 1 extending portion 35 and a circular portion 36 shown most clearly in Figure 2. Member 29 has axially extending inlet and outlet passages 33 and 34 therethrough which communicate with the opposite ends of the circuitous passage 32 as shown. The passage 32 and membrane 22 thus form a flow -through sample chamber. The spacial relationship of the anode 11 and cathode 12 to the passage 32 is shown in phan-tom in Figure 2. Member 29 is formed from electrically con-ductive material, such as silver, and is preferably of the same material as cathode 12. In any event, the materials of construction for cathode 12 and member 29 should be so selected as to prevent the formation of an undesirable "half cell". Member 29 also has an internally threadecl bore 37.
An inverted cup-shaped sealing member 30 coaxially surrounds and may be in sliding contact with the member 29 and sealingly engages the O-ring 27. An electrically conductive compression spring 38 is located between the sealing member 30 and the member 29. Sealing member 30 has a peripheral flange portion 47 formed with diametrically oppositely disposed bores 39 and 40 which are aligned with the bores 16 and 15 in the case member 14. Alignment pins 41 and 42 may have a press fit respectively in bores 16 and 15 of case member 14 and have a sliding fit within passages 39 and 40, respectively, of sealing member 30O
While two alignment pins are shown, it is understood that additional pins and associated bores may also be used if desired. Sealing member 30 is formed with axially extend-ing passages 43, 44 and 55 through the transverse end wall thereof as shown. An electrically conductive inlet tube 3L(li775t;6 1 45 passes slidably through passage 43 of sealing member 30 and has a sealing fit within the inlet passage 33 of member 29. An outlet tube 46 passes slidably through passage 44 of sealing member 30 and has a sealing fit within outlet pass-age 34 of member 29. A bolt 56 having a head 57 passes slidably through passage 55 of member 30 and is threaded into bore 37 of member 29 as shown. In Figure 1, bolt head 57 is located slightly above the transverse wall of member 30.
A cla~ping nut 48 is formed with an axial bore 51 and a counterbore 52 forming an annular shoulder portion 50.
Counterbore 52 has inner threads ~9 which are interengage-.lble with external threads 17 on case rnember 1~. As the clamping nut ~8 is threaded onto the case membor 14, the annular shoulder 50 is moved into mating contact with the flange 47 of sealing member 30 and forces sealing member 30 axially against O-ring 27 while at the same time exert-ing a compressive axial force on spring 38. The spring 38, in turn, exerts an axial force on the member 29 whereby the membrane 22 is stretched over and into close contact with the convex surface 8 of member 13 by clamping engage-ment oE said membrane between said convex surface 8 and the complemental concave end surface 31 of member 29. This clamping engagement maintains close contact between the membrane and both o-f said complementary surfaces. The O
-ring also forms a liquid-tight seal between the membrane 22 and peripheral portions of the member 29 as well as between the membrane and the recess wall 28. This prevents any loss of liquid from the chamber 32.
' ~ ~775~ti 1 Conductors 18 and 19 from the anode 11 and cathode 12, respectively, are connected through lines 60 and 53 to a detecting circuit shown schematically in block 54. The detecting circuit contains an appropriate power supply for the polarographic assembly, as well as indicators controlled by the signals produced by the polarographic assembly.
Conductor 19 may be grounded as shown~ It will be observed that the apparatus described includes means pro-viding an electrical connection from the cathode 12, through conductor 19, case 14, nut 48, sealing member 30 and compression spring 38 to the member 29. ~ther suitable means may be used to effect the electrical connection b~tween the cathode 12 and member 29, or example by the usc of a conductor connecting conductor 19 to lnlet tube 45, should it be ~ound desirable to form one or more of member 14, nut 48, spring 38 or member 30 of electrically non-conductive material. Thus, the member 29 is main-tained at the same electrical potential as the cathode 120 In the disclosed embodiment this potential is preferably ground potential; however, the particular potantial main-tained is not critical. This arrangement shields the anode from undesirable potentials, such as streaming potentials or static noise, which might otherwise interfere with the polarographic signal. The s-treaming potentials are 25 neutralized in this arrangement. ;
The illustrated embodiment of the invention is especially suited for continuous analysis of liquid samples for glucose content. In use, a liquid sample, such as blood, is caused to flow through inlet tube 45, into the flow -through chamber formed by passage 32 and membrane 22, and 775~6 1 then out through outlet tube 46. As shown by the arrows in Figure 2, the sample flows from inlet 33 in a straight line over a small part of the cathode, across the anode and over a part of the cathode, and then continues in an almost com-pletely circular path circumferentially over and along thecathode before exiting from the sample chamber through out-let 34. This flow pattern results in a desirable response time and reduces or prevents undesirable discharges directly over the anode.
The apparatus details of the present invention enable the membrane 22 to be mounted in a manner which minimizes the likelihood of damage during mounting and during sub-sequent use. I'his ls shown in more detail with rcfcrence to ~igures 3 and ~ which illustrate the manner Ln whLch a portion of the apparatus is assembled.
As shown in Figure 3, which represents a portion of the apparatus o~ Figure 1 prior to assembly, the recess 9 is filled with sufficient liquid, such as distilled water or suitable buffer solution 58, to completely cover convex surface 8. The membrane 22, preferably having gasket or O-ring 27 with central opening 59 therein attached thereto, is then ~loated on liquid 58. The ~-ring 27 and membrane 22 fit loosely within the sidewall 28 of recess 9 as shown~
The apparatus is then appropriately tilted and tapped so that any air or other gas bubbles initially trapped beneath membrane 22 can escape through the space between the edge of membrane 22 and the recess sidewall 28 and thence through the space between the O-ring 27 and said sidewall.
Membr!ane 22 is preferably sufficiently transparent to allow such bubbles and their movement t~o be properly observed.
10775Ei6 l The subassembly comprising the members 29 and 30, tubes 45 and 46, spring 38 and bolt 56 is then placed in the coaxial relationship with members 13 and 14 shown in partial cross-section in Figure 4. Members 29 and 30 are connected by bolt 56, and compression spring 38 forces member 29 away from member 30 until the head 57 of bolt 56 mates against member 30. In the assembly operation member 29 is pushed through opening 59 in O-ring 27 with which it has a snug fit and into contact with membrane 22 forcing said membrane into close contact with convex surface 8 as the concave end surface of member 29 stretches membrane 22 over said convex surace. Such pressure on membrane 22 ~orces the liquid located beneath membrane 22 out at the periphery o~ said membrane ancl through the opcrling between O-ring 27 and recess sidewall 28. Assembly of the apparatus is completed by application of clamping nut 48 to provide the assemblage shown in Figure l. The above apparatus and membrane ~ounting procedure enables the membrane 22 to be efectively mounted in close contact with the convex sur-face, such as in a polarographic electrode assembly, whileeliminating any undesirable gas bubb:Les and[or liquid Erom the space between the membrane and the convex surface. In polarographic electrode systems such undesirable materials can interfere with proper operation. A trapped gas bubble or other fluid could also rupture the membrane during mount-ing or subsequent use.
- When membrane 22 is used in an electrode sensing apparatus, it preferably contains an enzyme to assist in such sensing. One form of membrane useful in the present invention is shown in an enlarged vertical cross-section ~Q7756~
1 in Figure 5. This membrane comprises an upper nucleopore membrane 23, made, for example, of polycarbonate, and a lower membrane 24, made, for example, of cellulose acetate, peripherally joined to form an envelope having a layer of glucose oxidase 25 enclosed therewithin. In a further useful form, the membrane 22 has an electrically conduc-tive coating 26 deposited on the upper surface thereof, for example by vacuum deposition, which coating may be formed, for example, of gold, platinum, palladium, silver, alloys thereof or carbon. The material for coating 26 should be selected so as to prevent the formation of an ! undesirable "half cell" with cathode 12. ~t is preferable that coating Z6 be o e the same material as cathode 12 and member 29. Coating 26 is semi-permeab~e and pre~erably has a thickness of about 200 to 400 Angstroms. The nucleo-pore membrane 23 preferably has an average pore size of about 300 Angstroms prior to application of the coating 26, and the pore size of coating 26 is generally of the same order. It is essential that the coating 26 be "wettable" by the liquid sample material passing through the sample chamber. It has been found that treatment of the coating 26 with an anionic surfactant, such as sodium dodecyl sulfate, renders the coating sufficiently wettable to be used with blood samples. It is understood that other suitable surfactants may also be used.
The electrically conductive coating 26 is in electri-cal contact with member 29 and thus is at the same potential as cathode 12. This further assists in the elimination of undesirable potentials which might develop during operation.
.
Apparatus employing semi-permeable membranes are ,,~ !
employed for various purposes. They are used, for example, in reverse osmosis processes to,separate components of a fluid mixture. They are also used in electrode apparatus for the detection and measurement of specific components in a fluid mixture.
One apparatus, for example, previously suggested for the detection and measurement of glucose in body fluids, such as blood, consisted of a sample chamber into which samples were introduced in discrete individual amounts. One : side of a semi-permeable membrane containing glucose oxidase was in communication with,the sample chamber and was capable of allowing portions of the sample in the chamber to pass therethrough. During this passage the glucose oxidase in the membrane catalyzed the oxidation of the glucose in the presence of oxygen in the sample to form hydrogen peroxide. A polarographic anode-cathoae assembly was posi-tioned in close proximity to the other side of the membrane and was capable of measuring the amount of hydrogen peroxide ~-formed, thus detecting and measuring the amount of glucose;n the sample.
"~
~ A; ~ ~
'. ' ;, ,': , ,. '. . . . ~
~77S~;6 1 This prior art apparatus had several disadvantages.
First, when attempts were made to miniaturize the apparatus, the means for mounting the membrane against the polaro-graphic electrode assembly often caused undesirable rupture of the membrane during mounting or subsequent use. Second, there was often an undesirable slowness in electrode re-sponse due to variations in membrane mounting and due to fluids, such as gases, being trapped between the membrane and the electrode assembly. The prior art apparatus was also not capable of handling continuous sampling conditions.
These and other disadvantages of the prior art mem-brane apparatus are overcome by the apparatus of the pre-sent invention.
SUMMARY OF T~IF INVF.NTION
In accordance with the present invention, apparatus is provided wherein a membrane is supported in close contact with a surface, said apparatus comprising a first member having a convex surface, a second member having a concave surface facing and complemental to said convex surface, a membrane interposed between said complemental suraces, and means cooperable with said first and second members for effecting clamping engagement of said membrane between said complemental surfaces whereby said membrane is stretch-ed over and in close contact with said convex surfaceO
During the assembly of this apparatus any fluid located between the membrane and the convex surface is allowed to escape therefrom around the edges of the membrane.
~17~
Figure 1 is a vertical cross-sectional view of one illustrative embodiment of apparatus of the present in-vention employing an electrode assembly with ancillary circuits shown schematically in block diagram form;
Figure 2 is an end view of the sample chamber member of the apparatus of Figure l;
Figure 3 is a vertical cross-sectional view of a por-tion of the apparatus of Figure 1 illustrating one step in the mounting of a membrane used with such apparatus;
Figure ~ is a view similar to that of Figure 3 lllustrat;ng a ~urther step in the mounting of l;hc membrane;
and Figure 5 is an enlarged fragmentary vertical cross -sectional view of a semi-permeable membrane useful in the apparatus of the present invention.
DESCRIPTION OF THE INVENTION
Referring to Figure 1, the apparatus 10 represents an illustrative embodiment of one form of the novel ap-paratus useful for sensing glucose in a sample fluid. Ithas a hydrogen peroxide detecting polarographic anode -cathode assembly comprising a central cylindrical anode 11 and a surrounding annular cathode 12 encased in a general-ly cylindrical insulating first or membrane support member 13. The anode is conveniently formed from platinum and the cathode is conveniently formed from silver. However, other electrically conductive anode and cathode materials can be ~ ~ 7 ~
1 used. The first member 13 is conveniently formed of an organoplastic material, such as epoxy resin, and is enclosed within a generally cup-shaped electrically conductive case member 14 which is preferably formed of stainless steel.
Case member 14 is formed in its end face with diametrically oppositely disposed parallel bores 15 and 16 and is also formed with external threads 17. Electrical conductors 18 and 19 extend from the anode 11 and cathode 12, respectively, through first member 13 and through suitable openings in case member 14. Conductor 18 is preferably insulated by spacing from the case 14, as shown, whereas conductor 19 is preferably in circuit therewith. The upper suraces 20 and 21 of anode 11 and cathode 12, resp~ct:ively, are co-incident with and orm part o~ a ~enerally convex surface 8 which constitutes the b~ttom wall of a generally cyl~ndri-cal recess 9 formed in the upper surface of support member 13. Recess 9 has cylindrical sidewall portion 28 therein.
A circular semi-permeable membrane 22 overlays the convex surface 8, including surfaces 20 and 21~ An annular gasket, such as an O-ring 27, is placed on the peripheral edge portions of membrane 22 within the recess 9 as shown. It is covenient to employ a membrane unit in which the O-ring 27 is attached to the membrane 22.
A generally cylindrical second sample chamber or mem-brane positioning member 29 of smaller diameter than the cylindrical sidewall 28 and having a concave lower end surface 31 facing and complemental to convex surface 8 is positio~ned on membrane 22 coaxially within the recess 9 and O-ring 27 The concave lower end surface 31 is formed with recess means which may take the form of a groove de-fining a sample flow passage 32 having a straight diametrically 1~77566 1 extending portion 35 and a circular portion 36 shown most clearly in Figure 2. Member 29 has axially extending inlet and outlet passages 33 and 34 therethrough which communicate with the opposite ends of the circuitous passage 32 as shown. The passage 32 and membrane 22 thus form a flow -through sample chamber. The spacial relationship of the anode 11 and cathode 12 to the passage 32 is shown in phan-tom in Figure 2. Member 29 is formed from electrically con-ductive material, such as silver, and is preferably of the same material as cathode 12. In any event, the materials of construction for cathode 12 and member 29 should be so selected as to prevent the formation of an undesirable "half cell". Member 29 also has an internally threadecl bore 37.
An inverted cup-shaped sealing member 30 coaxially surrounds and may be in sliding contact with the member 29 and sealingly engages the O-ring 27. An electrically conductive compression spring 38 is located between the sealing member 30 and the member 29. Sealing member 30 has a peripheral flange portion 47 formed with diametrically oppositely disposed bores 39 and 40 which are aligned with the bores 16 and 15 in the case member 14. Alignment pins 41 and 42 may have a press fit respectively in bores 16 and 15 of case member 14 and have a sliding fit within passages 39 and 40, respectively, of sealing member 30O
While two alignment pins are shown, it is understood that additional pins and associated bores may also be used if desired. Sealing member 30 is formed with axially extend-ing passages 43, 44 and 55 through the transverse end wall thereof as shown. An electrically conductive inlet tube 3L(li775t;6 1 45 passes slidably through passage 43 of sealing member 30 and has a sealing fit within the inlet passage 33 of member 29. An outlet tube 46 passes slidably through passage 44 of sealing member 30 and has a sealing fit within outlet pass-age 34 of member 29. A bolt 56 having a head 57 passes slidably through passage 55 of member 30 and is threaded into bore 37 of member 29 as shown. In Figure 1, bolt head 57 is located slightly above the transverse wall of member 30.
A cla~ping nut 48 is formed with an axial bore 51 and a counterbore 52 forming an annular shoulder portion 50.
Counterbore 52 has inner threads ~9 which are interengage-.lble with external threads 17 on case rnember 1~. As the clamping nut ~8 is threaded onto the case membor 14, the annular shoulder 50 is moved into mating contact with the flange 47 of sealing member 30 and forces sealing member 30 axially against O-ring 27 while at the same time exert-ing a compressive axial force on spring 38. The spring 38, in turn, exerts an axial force on the member 29 whereby the membrane 22 is stretched over and into close contact with the convex surface 8 of member 13 by clamping engage-ment oE said membrane between said convex surface 8 and the complemental concave end surface 31 of member 29. This clamping engagement maintains close contact between the membrane and both o-f said complementary surfaces. The O
-ring also forms a liquid-tight seal between the membrane 22 and peripheral portions of the member 29 as well as between the membrane and the recess wall 28. This prevents any loss of liquid from the chamber 32.
' ~ ~775~ti 1 Conductors 18 and 19 from the anode 11 and cathode 12, respectively, are connected through lines 60 and 53 to a detecting circuit shown schematically in block 54. The detecting circuit contains an appropriate power supply for the polarographic assembly, as well as indicators controlled by the signals produced by the polarographic assembly.
Conductor 19 may be grounded as shown~ It will be observed that the apparatus described includes means pro-viding an electrical connection from the cathode 12, through conductor 19, case 14, nut 48, sealing member 30 and compression spring 38 to the member 29. ~ther suitable means may be used to effect the electrical connection b~tween the cathode 12 and member 29, or example by the usc of a conductor connecting conductor 19 to lnlet tube 45, should it be ~ound desirable to form one or more of member 14, nut 48, spring 38 or member 30 of electrically non-conductive material. Thus, the member 29 is main-tained at the same electrical potential as the cathode 120 In the disclosed embodiment this potential is preferably ground potential; however, the particular potantial main-tained is not critical. This arrangement shields the anode from undesirable potentials, such as streaming potentials or static noise, which might otherwise interfere with the polarographic signal. The s-treaming potentials are 25 neutralized in this arrangement. ;
The illustrated embodiment of the invention is especially suited for continuous analysis of liquid samples for glucose content. In use, a liquid sample, such as blood, is caused to flow through inlet tube 45, into the flow -through chamber formed by passage 32 and membrane 22, and 775~6 1 then out through outlet tube 46. As shown by the arrows in Figure 2, the sample flows from inlet 33 in a straight line over a small part of the cathode, across the anode and over a part of the cathode, and then continues in an almost com-pletely circular path circumferentially over and along thecathode before exiting from the sample chamber through out-let 34. This flow pattern results in a desirable response time and reduces or prevents undesirable discharges directly over the anode.
The apparatus details of the present invention enable the membrane 22 to be mounted in a manner which minimizes the likelihood of damage during mounting and during sub-sequent use. I'his ls shown in more detail with rcfcrence to ~igures 3 and ~ which illustrate the manner Ln whLch a portion of the apparatus is assembled.
As shown in Figure 3, which represents a portion of the apparatus o~ Figure 1 prior to assembly, the recess 9 is filled with sufficient liquid, such as distilled water or suitable buffer solution 58, to completely cover convex surface 8. The membrane 22, preferably having gasket or O-ring 27 with central opening 59 therein attached thereto, is then ~loated on liquid 58. The ~-ring 27 and membrane 22 fit loosely within the sidewall 28 of recess 9 as shown~
The apparatus is then appropriately tilted and tapped so that any air or other gas bubbles initially trapped beneath membrane 22 can escape through the space between the edge of membrane 22 and the recess sidewall 28 and thence through the space between the O-ring 27 and said sidewall.
Membr!ane 22 is preferably sufficiently transparent to allow such bubbles and their movement t~o be properly observed.
10775Ei6 l The subassembly comprising the members 29 and 30, tubes 45 and 46, spring 38 and bolt 56 is then placed in the coaxial relationship with members 13 and 14 shown in partial cross-section in Figure 4. Members 29 and 30 are connected by bolt 56, and compression spring 38 forces member 29 away from member 30 until the head 57 of bolt 56 mates against member 30. In the assembly operation member 29 is pushed through opening 59 in O-ring 27 with which it has a snug fit and into contact with membrane 22 forcing said membrane into close contact with convex surface 8 as the concave end surface of member 29 stretches membrane 22 over said convex surace. Such pressure on membrane 22 ~orces the liquid located beneath membrane 22 out at the periphery o~ said membrane ancl through the opcrling between O-ring 27 and recess sidewall 28. Assembly of the apparatus is completed by application of clamping nut 48 to provide the assemblage shown in Figure l. The above apparatus and membrane ~ounting procedure enables the membrane 22 to be efectively mounted in close contact with the convex sur-face, such as in a polarographic electrode assembly, whileeliminating any undesirable gas bubb:Les and[or liquid Erom the space between the membrane and the convex surface. In polarographic electrode systems such undesirable materials can interfere with proper operation. A trapped gas bubble or other fluid could also rupture the membrane during mount-ing or subsequent use.
- When membrane 22 is used in an electrode sensing apparatus, it preferably contains an enzyme to assist in such sensing. One form of membrane useful in the present invention is shown in an enlarged vertical cross-section ~Q7756~
1 in Figure 5. This membrane comprises an upper nucleopore membrane 23, made, for example, of polycarbonate, and a lower membrane 24, made, for example, of cellulose acetate, peripherally joined to form an envelope having a layer of glucose oxidase 25 enclosed therewithin. In a further useful form, the membrane 22 has an electrically conduc-tive coating 26 deposited on the upper surface thereof, for example by vacuum deposition, which coating may be formed, for example, of gold, platinum, palladium, silver, alloys thereof or carbon. The material for coating 26 should be selected so as to prevent the formation of an ! undesirable "half cell" with cathode 12. ~t is preferable that coating Z6 be o e the same material as cathode 12 and member 29. Coating 26 is semi-permeab~e and pre~erably has a thickness of about 200 to 400 Angstroms. The nucleo-pore membrane 23 preferably has an average pore size of about 300 Angstroms prior to application of the coating 26, and the pore size of coating 26 is generally of the same order. It is essential that the coating 26 be "wettable" by the liquid sample material passing through the sample chamber. It has been found that treatment of the coating 26 with an anionic surfactant, such as sodium dodecyl sulfate, renders the coating sufficiently wettable to be used with blood samples. It is understood that other suitable surfactants may also be used.
The electrically conductive coating 26 is in electri-cal contact with member 29 and thus is at the same potential as cathode 12. This further assists in the elimination of undesirable potentials which might develop during operation.
Claims (2)
1. Apparatus employing a semi-permeable membrane wherein the membrane is supported against a surface and wherein the likelihood of damage to such membrane during mounting and use is minimized comprising in combination a first member formed with a recess having a cylindrical sidewall and a bottom having a convex surface, a membrane, an annular gasket, a second member having a concave end surface and clamping means, said second member being capable of fitting within said gasket and of positioning said membrane against said first member wherein said membrane is stretched over said convex surface of said first member by the complemental concave end surface of said second member to effect close contact between said membrane and said convex surface, said annular gasket in an unstressed condition loosely fitting within said cylindrical sidewall of said recess of said first member, any fluid located between said membrane and said convex surface of said first member being forced outward by said membrane stretching and being allowed to pass through the space formed by the loose fitting relationship between said annular gasket and said cylindrical sidewall of said first member, said clamping means then being capable of applying compressive force to said annular gasket and to said second member to form a fluid-tight seal between said cylindrical sidewall of said first member and said second member through said annular gasket and to hold said membrane in stretched relationship against and in close contact with said first member.
2. A glucose sensing apparatus comprising in com-bination a hydrogen peroxide detecting polarographic assembly having a recess with a convex bottom surface portion and a surrounding cylindrical sidewall, said assembly comprising an anode having a circular end surface and a cathode having an annular end surface in spaced surrounding relation to said anode surface, each of said end surfaces forming part of said convex surface portion of said assembly; a semi-permeable membrane containing glucose oxidase overlying and in close contact with said convex surface; a generally cylindrical elec-trically conductive flow chamber member having a concave end surface portion formed with flow passage means therein and having inlet and outlet means communicating with said flow passage means, said concave end surface being complemental to and aligned with said convex surface of said polarographic assembly and in overlying contact with the portion of said membrane in contact with said convex surface, said flow passage means and said mem-brane forming a flow-through sample chamber providing a sample flow pattern wherein a sample flowing therethrough flows in a straight line over a small portion of said cathode surface, diametrically across said anode surface and thence circumferen-tially over a substantial portion of said cathode surface before exiting from said sample chamber, an o-ring type sealing means surrounding said flow chamber member and in an unstressed con-dition loosely fitting within said cylindrical sidewall of said polarographic assembly and in contact with the adjacent upper surface portion of said membrane; an inverted generally cup-shaped sealing member disposed coaxially over said flow-chamber member and having an annular surface engaging said o-ring; means for clamping said sealing member to said polarographic assembly in a manner to effect compression of said o-ring and sealing contact thereof with said chamber member, said cylindrical side-wall of said polarographic assembly and said membrane, compres-sion spring means disposed between said sealing member and said chamber member for biasing the latter axially toward said membrane; and means for effecting an electrical connection be-tween said cathode and said flow chamber member.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US64197875A | 1975-12-18 | 1975-12-18 | |
| US05/683,807 US4092233A (en) | 1975-12-18 | 1976-05-06 | Membrane apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1077566A true CA1077566A (en) | 1980-05-13 |
Family
ID=27093892
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA266,637A Expired CA1077566A (en) | 1975-12-18 | 1976-11-26 | Polarographic membrane apparatus |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPS5285077A (en) |
| CA (1) | CA1077566A (en) |
| DE (1) | DE2657351C3 (en) |
| FR (1) | FR2335842A1 (en) |
| GB (1) | GB1528270A (en) |
| HU (1) | HU174040B (en) |
| IT (1) | IT1066608B (en) |
| NL (1) | NL7613869A (en) |
| SE (1) | SE7614263L (en) |
Families Citing this family (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2005418B (en) * | 1977-07-26 | 1982-04-21 | Searle & Co | Electrochemical sensor system |
| US4172770A (en) * | 1978-03-27 | 1979-10-30 | Technicon Instruments Corporation | Flow-through electrochemical system analytical method |
| JPS5648549A (en) * | 1979-09-24 | 1981-05-01 | Albery Wyndham John | Electrochemical sensor for oxygen* halogen and nitrous oxide |
| JPS5770448A (en) * | 1980-10-20 | 1982-04-30 | Matsushita Electric Ind Co Ltd | Enzyme electrode |
| DE3110183C2 (en) * | 1981-03-17 | 1983-12-01 | Franz Dr.-Ing. 1000 Berlin Wallner | Membrane osmometer |
| US4415666A (en) * | 1981-11-05 | 1983-11-15 | Miles Laboratories, Inc. | Enzyme electrode membrane |
| JPS5961772A (en) * | 1982-09-28 | 1984-04-09 | ザ・イエロ−・スプリングス・インストルメント・カンパニ−・インコ−ポレ−テツド | Liquid chromatograph enzyme electrode detector |
| DE3242457A1 (en) * | 1982-11-12 | 1984-05-17 | Dr. Bruno Lange Gmbh, 1000 Berlin | Measurement system with at least one ion-sensitive electrode |
| JPS59133455A (en) * | 1983-01-21 | 1984-07-31 | Hitachi Ltd | Analyzer providing plural sensors |
| FR2554593B1 (en) * | 1983-11-08 | 1986-09-19 | Comp Generale Electricite | ELECTROCHEMICAL DOSING HEAD WITH SCREENED ELECTRODES |
| JPS60114760A (en) * | 1983-11-28 | 1985-06-21 | Hitachi Ltd | Maltose sensor |
| SE452515B (en) * | 1985-10-28 | 1987-11-30 | Gambro Lundia Ab | ELEKTRODMETSYSTEM |
| US4759828A (en) * | 1987-04-09 | 1988-07-26 | Nova Biomedical Corporation | Glucose electrode and method of determining glucose |
| DE3815004A1 (en) * | 1988-05-03 | 1989-11-16 | Gimat | DEVICE FOR THE POLAROGRAPHIC MEASUREMENT OF THE OXYGEN CONTENT IN LIQUID AND GASEOUS MEDIA |
| US4995402A (en) * | 1988-10-12 | 1991-02-26 | Thorne, Smith, Astill Technologies, Inc. | Medical droplet whole blood and like monitoring |
| DE9319955U1 (en) * | 1993-12-24 | 1994-02-24 | Berthold, Christian, Dr.rer.nat., 04736 Meinsberg | Electrochemical gas sensor |
| DE19524354C2 (en) * | 1995-07-04 | 1998-07-02 | Ums Umwelt Membran Und Sensort | Device for measuring gas partial pressures, in particular oxygen |
| CN103566759B (en) * | 2013-11-11 | 2015-04-29 | 江苏白雪电器股份有限公司 | RO (reverse osmosis) membrane filter element component inflowing and discharging water at same end |
| CN103566763B (en) * | 2013-11-11 | 2015-04-29 | 江苏白雪电器股份有限公司 | Ultrafiltration membrane filter element component inflowing and discharging water at same end |
| CN109499368B (en) * | 2018-11-01 | 2022-04-26 | 江苏坤奕环境技术股份有限公司 | Flow guide disc for high-pressure disc tubular membrane component |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1084080A (en) * | 1964-11-30 | Beckman Instruments Inc | ||
| US3785948A (en) * | 1972-02-14 | 1974-01-15 | Dudley Wright H | Electrochemical oxygen detector |
-
1976
- 1976-11-26 CA CA266,637A patent/CA1077566A/en not_active Expired
- 1976-12-06 IT IT5248676A patent/IT1066608B/en active
- 1976-12-07 GB GB5100776A patent/GB1528270A/en not_active Expired
- 1976-12-13 HU HU76MI606A patent/HU174040B/en unknown
- 1976-12-14 NL NL7613869A patent/NL7613869A/en not_active Application Discontinuation
- 1976-12-16 JP JP15040076A patent/JPS5285077A/en active Granted
- 1976-12-17 FR FR7638168A patent/FR2335842A1/en active Granted
- 1976-12-17 SE SE7614263A patent/SE7614263L/en not_active Application Discontinuation
- 1976-12-17 DE DE19762657351 patent/DE2657351C3/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| HU174040B (en) | 1979-10-28 |
| GB1528270A (en) | 1978-10-11 |
| FR2335842B1 (en) | 1979-03-09 |
| NL7613869A (en) | 1977-06-21 |
| FR2335842A1 (en) | 1977-07-15 |
| JPS5285077A (en) | 1977-07-15 |
| DE2657351B2 (en) | 1981-06-25 |
| DE2657351A1 (en) | 1977-07-07 |
| SE7614263L (en) | 1977-06-19 |
| DE2657351C3 (en) | 1982-06-24 |
| IT1066608B (en) | 1985-03-12 |
| JPS57466B2 (en) | 1982-01-06 |
| AU2013276A (en) | 1978-06-01 |
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