Solid ion-selective electrode

Abstract

To provide a solid ion-selective electrode.SOLUTION: An ion-selective electrode (ISE) assembly 100 can be installed in a sample pathway of a biological testing system to measure an ion concentration in a sample fluid flowing through the sample pathway 120. A transducer membrane 129 is placed in the housing and positioned to contact the sample pathway. A threaded portion 128 is advanced into a socket of the housing to force the membrane against a sealing portion of the sample pathway to prevent sample fluid from being retained in the housing after testing. Sealing may be accomplished without adhesives or sealants, but instead relies on mechanical pressure of the ridged portions.SELECTED DRAWING: Figure 8

Description

[Background technology]

[0001] Various types of testing related to patient diagnosis and treatment can be performed by analyzing a patient's microorganisms or "germs." Pathogens are microscopic living organisms such as bacteria, fungi, or viruses, which may be unicellular or multicellular. Biological samples containing the patient's microorganisms can be collected from a patient's infection, body fluid, or abscess, placed in a test panel or array, combined with various reagents, cultured, and analyzed to aid in patient treatment. Automated biochemical analyzers or biological testing systems have been developed to meet the needs of medical facilities and other institutions to expedite the analysis of patient samples, improve the accuracy and reliability of assay results, and aid in determining the effectiveness of various antimicrobial agents when compared to analyses using manual operations.

[0002] Such biological test systems may include the use of ion-selective electrodes to determine ion concentrations in biological samples. This may involve pumping the sample fluid through a channel that passes through or near the ion-selective electrodes so that a sensing element is exposed to the sample fluid. The sensing element interacts with the fluid sample and generates a voltage that can be measured to determine the concentration of a particular substance (e.g., sodium, potassium, chloride) in the sample fluid.

[0003] These electrodes and corresponding systems are often expensive, have long response times, and / or require large sample sizes. In addition, many ion-selective electrodes may have a poor seal between the conductive core and the ion-selective membrane. This can often result in the occurrence of a phenomenon called "carry-over contamination," in which the sample remains in the instrument after analysis, making subsequent analysis of other samples inaccurate and unreliable. Summary of the Invention [Means for solving the problem]

[0004] The present invention provides, for example, the following items. (Item 1) An ion selective electrode, the ion selective electrode comprising: (a) a housing, the housing comprising: (i) a sample path passing through the housing, the sample path including a sensing aperture; (ii) an electrode socket defined by an opening in the housing, the electrode socket comprising a cavity within the housing accessible through the opening; (iii) a transducer receiving portion positioned within the cavity and connected to the sample path through the sensing opening; a housing comprising: (b) a sensor comprising a membrane structure and a membrane, (i) the membrane structure is configured to position the membrane at the sensing opening such that, when the sensor is installed within the transducer receiving portion, a liquid solution passing through the sample path contacts the membrane; (ii) a sensor, wherein the membrane is configured to generate an electrical potential upon contact with the liquid solution; and (c) a socket plug adapted to fit into the electrode socket and bias the membrane against the sensing aperture; (d) an electrical contact passing through the socket plug and coupled to the sensor; Equipped with The electrical contact is usable to measure the electrical potential from outside the housing, an ion selective electrode. (Item 2) The electrical contacts include an inner contact and an outer contact; (a) the socket plug is configured to position the internal contact against the membrane structure when mated with the electrode socket; (b) the external contact extends from the electrical contact to the outside of the housing; (c) the internal contact is coupled to the external contact and configured to transfer the electrical potential from the membrane structure to the external contact. (Item 3) 2. The ion selective electrode of claim 1, wherein the socket plug comprises threads configured to couple the socket plug with the electrode socket and bias the membrane against the sensing aperture when the socket plug is advanced into the electrode socket. (Item 4) 4. The ion selective electrode of claim 3, wherein the socket plug is configured such that when threaded into the electrode socket, it contacts the membrane structure, causing the membrane to compress against the sensing aperture and form a liquid-tight seal between the membrane and the sensing aperture. (Item 5) Item 5. The ion selective electrode of item 4, wherein the socket plug is configured to form a liquid-tight seal between the socket plug and the electrode socket when threaded into the electrode socket. (Item 6) Item 10. The ion-selective electrode of item 1, wherein the membrane structure comprises conductive graphite. (Item 7) 7. The ion selective electrode of claim 6, wherein the membrane comprises a solid ion selective membrane. (Item 8) 8. The ion-selective electrode according to claim 7, wherein the solid ion-selective membrane is cast directly onto the conductive graphite. (Item 9) Item 10. The ion selective electrode of item 1, wherein the contact area defined by the portion of the membrane exposed to the sample pathway is about 0.006 square inches. (Item 10) 2. The ion selective electrode of claim 1, wherein the sensor self-seals against the sensing opening when the electrical contact is mated with the electrode socket. (Item 11) Item 11. The ion selective electrode of item 10, wherein the sensor and the sensing aperture are free of any other sealing features or adhesives. (Item 12) Item 2. The ion selective electrode of item 1, wherein the sensor consists essentially of the membrane structure and the membrane. (Item 13) Item 1. The ion selective electrode of item 1, wherein the membrane is configured to generate the potential based on an ion concentration of an ion in a liquid solution, the ion being selected from the group consisting of potassium, sodium, and chloride. (Item 14) 1. A method of assembling an ion selective electrode, the method comprising: (a) manufacturing a housing having dimensions selected to suit a desired application, said housing comprising: (i) a sample path passing through the housing, the sample path including a sensing aperture; (ii) an electrode socket defined by an opening in the housing, the electrode socket comprising a cavity within the housing accessible through the opening; (iii) a transducer receiving portion positioned within the cavity and connected to the sample path through the sensing opening; and (b) creating a membrane structure having dimensions selected to fit within said transducer receiving portion and producing a sensor by directly casting a membrane onto said membrane structure; (i) the membrane structure is configured to position the membrane in the sensing opening such that, when the sensor is coupled with the transducer receiving portion, a liquid solution passing through the sample path contacts the membrane; (ii) the membrane is configured to generate an electrical potential upon contact with the liquid solution; And, (c) placing the sensor in the transducer receiving portion; (d) advancing a socket plug into the electrode socket to bias the membrane against the sensing aperture; (e) coupling an electrical contact to the sensor; Including, The method, wherein the electrical contacts are usable to measure the electrical potential from outside the housing. (Item 15) 15. The method of claim 14, further comprising configuring the membrane to generate the electrical potential based on an ion concentration of an ion in the liquid solution, the ion being selected from the group consisting of potassium, sodium, and chloride. (Item 16) 15. The method of claim 14, wherein the membrane structure comprises conductive graphite, the membrane comprises a solid ion-selective membrane, and the method further comprises preventing any direct physical contact with the membrane after generation of the sensor until the sensor is placed within the transducer receiving portion. (Item 17) By screwing the socket plug into the electrode socket, the electrical contacts are mated with the electrode socket, resulting in (a) forming a liquid-tight seal between the socket plug and the electrode socket; (b) forming a liquid-tight seal between the membrane and the sensing opening; Item 15. The method of item 14, further comprising: (Item 18) 20. The method of claim 17, further comprising producing the sensor and forming the liquid-tight seal between the membrane and the sensing opening without any adhesive and without any other sealing features within the sensor and the sensing opening. (Item 19) A reference electrode, the reference electrode comprising: (a) a housing, the housing comprising: (i) a sample path passing through the housing, the sample path including a sensing aperture; (ii) a reservoir within the housing and a cap adapted to seal the reservoir; (iii) an electrode socket within the reservoir; (iv) a transducer receiving portion positioned within the electrode socket and connected to the sample pathway through the sensing opening; a housing comprising: (b) a sensor comprising a membrane structure and a membrane, (i) the membrane structure is configured to position the membrane at the sensing opening such that, when the sensor is installed within the transducer receiving portion, a liquid solution passing through the sample path contacts the membrane; (ii) the membrane is configured to generate an electrical potential upon contact with the liquid solution; A sensor, (c) a socket plug adapted to fit into the electrode socket and bias the membrane against the sensing aperture; (d) Electrical contacts and Equipped with A reference electrode, wherein the electrical contact passes through the housing, enters the reservoir, and passes through the electrode socket so that a proximal tip of the electrical contact is adjacent to the sensor socket plug, the electrical contact being configured to transmit an electrical potential from the liquid at the proximal tip to a distal tip outside the housing. (Item 20) 20. The reference electrode of claim 19, wherein the socket plug comprises threads configured to couple the socket plug with the electrode socket and bias the membrane against the sensing aperture when the socket plug is advanced into the electrode socket. (Item 21) 21. The reference electrode of claim 20, wherein the socket plug is configured such that when threaded into the electrode socket, it contacts the membrane structure, causing the membrane to compress against the sensing aperture and form a liquid-tight seal between the membrane and the sensing aperture. While the specification concludes with claims particularly pointing out and distinctly claiming the invention, it is believed the invention will be better understood from the following description of certain examples considered in conjunction with the accompanying drawings, in which like reference numerals identify the same elements and in which: [Brief explanation of the drawings]

[0005] [Figure 1] FIG. 1 is a schematic diagram of an exemplary biological test system.

[0006] [Figure 2] FIG. 2 is a perspective view of an exemplary ion selective electrode assembly with the electrode assembly removed.

[0007] [Figure 3] FIG. 3 is a cross-sectional view of the ion selective electrode assembly taken along line AA in FIG.

[0008] [Figure 4] FIG. 4 is a top-down view of the ion selective electrode assembly of FIG.

[0009] [Figure 5] FIG. 5 is an alternative perspective view of the ion selective electrode assembly of FIG.

[0010] [Figure 6A] FIG. 6A is a perspective view of an exemplary transducer assembly that can be used with the ion selective electrode assembly of FIG.

[0011] [Figure 6B] FIG. 6B is an alternative perspective view of the transducer assembly of FIG. 6A.

[0012] [Figure 7] FIG. 7 is a perspective view of an exemplary transducer of the transducer assembly of FIG. 6A.

[0013] [Figure 8] 8 is a cross-sectional view of an ion selective electrode assembly along line AA in FIG. 2, including the transducer assembly of FIG.

[0014] [Figure 9] FIG. 9 is a schematic diagram of an exemplary reference electrode.

[0015] [Figure 10] FIG. 10 is a schematic diagram of the reference electrode of FIG. 9 showing internal details. DETAILED DESCRIPTION OF THE INVENTION

[0016] The drawings are not intended to be limiting in any way, and it is contemplated that various embodiments of the invention may be practiced in a variety of other ways, including those not necessarily depicted in the drawings. The accompanying drawings, which are incorporated in and form a part of this specification, illustrate certain aspects of the invention and, together with the description, serve to explain the principles of the invention; however, it should be understood that the invention is not limited to the precise arrangements shown.

[0017] The following description of certain examples of the present invention should not be used to limit the scope of the present invention. Other examples, features, aspects, embodiments, and advantages of the present invention will become apparent to those skilled in the art from the following description, which is by way of example only and is one of the best modes contemplated for carrying out the invention. As will be recognized, the present invention is capable of other different and obvious aspects, all without departing from the present invention. Therefore, the drawings and description should be regarded as illustrative in nature, and not restrictive.

[0018] It should be understood that any one or more of the teachings, expressions, versions, examples, etc. described herein may be combined with any one or more of the other teachings, expressions, versions, examples, etc. described herein. The teachings, expressions, versions, examples, etc. described below should therefore not be viewed in isolation from one another. Various suitable ways in which the teachings herein may be combined will be readily apparent to those skilled in the art in light of the teachings herein. Such modifications and variations are intended to be included within the scope of the claims.

[0019] As described, many conventional ion-selective electrodes (“ISEs”) are disadvantageous due to a variety of factors. Some conventional ISEs are relatively complex, which can affect cost and reliability. Some conventional ISEs may also use adhesives to attach or seal various components, which may contaminate the sample fluid and cause erroneous measurements, or the adhesives may degrade over time, limiting shelf life or increasing the risk of carryover contamination. Many conventional ion-selective electrodes may also suffer from slow response times and may require exposure to relatively large amounts of sample to provide accurate results. The implementations disclosed herein, and variations thereof, offer numerous advantages over conventional ISEs.

[0020] I. Exemplary Ion-Selective Electrode Assemblies

[0021] FIG. 1 is a schematic diagram of an exemplary biological test system 10. The biological test system 10 includes a processor 12 configured to operate various components of the biological test system 10 and also configured to receive and generate data associated with the results of biological tests. A sample source 14 is operable by the processor 12 to provide a flow of sample fluid, which travels through a sample path 18 and exits at a sample waste device 16. The sample fluid may include biological samples, reagents, and other fluids and may be prepared prior to introduction into the biological test system 10, or, in some implementations, may be mixed and prepared by components of the biological test system 10. One or both of the sample source 14 and the sample waste device 16 may include valves, pumps, and other fluid control components, or positive / negative fluid pressure may be provided by devices upstream or downstream of the sample path 18.

[0022] The sample path (18) is a fluid channel having variable length, path, and characteristics depending on the particular implementation of the biological test system (10). For example, in some implementations, the sample path (18) may be a single path that transports the sample fluid by or through one or more sensing elements (20). In some implementations, the sample path (18) may split (or redirect) the flow of the sample fluid into one or more paths. Sensing elements (20) are positioned along the sample path (18) to contact the sample fluid as it flows through the sample path (18) and determine one or more properties of the sample fluid. This may include, for example, the sample fluid passing through the sensing element (20) or the sensing element (20) protruding into the sample path (18). Determining the sample fluid properties may be performed in various ways and, in the case of an ISE, may include measuring a voltage or other property generated as a result of the sample fluid contacting the active portion of the sensing element (20).

[0023] In some implementations, the processor 12 may operate the sample source 14 and / or the sample waste device 16 and control the flow of sample fluid along the sample path 18. When the sample fluid contacts the sensing element 20, a voltage is generated and received by the sensing element 20. The generated voltage may be transmitted to the processor 12, or data indicative of the voltage may be transmitted to the processor 12, where it may be used by the processor 12 to generate a result indicative of the concentration of ions (e.g., sodium, potassium, chloride) in the sample fluid. Such a result may then be transmitted to another device, stored in memory, displayed on a display device, or otherwise used by the processor 12, as would be apparent to one of ordinary skill in the art in light of this disclosure.

[0024] FIG. 2 is a perspective view of an exemplary ion-selective electrode ("ISE") assembly (100) with the transducer assembly (e.g., transducer assembly (122) as shown in FIGS. 6A and 6B) removed. The complete ISE assembly (100) can be used with a biological test system (10) as a sensing element (20). The ISE assembly (100) can be installed within the biological test system (10) so that the sample path (18) passes through the ISE assembly (100). The ISE assembly (100) includes a housing (102) that is shaped and adapted to fit within a receiver portion of the biological test system (10) to integrate the ISE assembly (100) with the sample path (18). The housing (102) can include features to aid in placement, such as a set of mounting tabs (108), that can align with and be inserted into an appropriately sized cavity in a nearby structure. The housing (102) itself may also include contoured edges, grooves, and other exterior features that aid in placement and orientation.

[0025] The sample input 104 is positioned on the housing 102 so that the sample input 104 is aligned with a source of sample fluid (e.g., sample source 14) when the ISE assembly 100 is coupled to the biological test system 10. The sample path seal 110 surrounds the sample input 104 and may mate with a mating structure when the ISE assembly 100 is installed in the biological test system 10 to aid in sealing between the sample source 14 and the sample input 104. The sample path seal 110, like the mounting tabs 108, may also aid in proper installation of the ISE assembly 100. The transducer assembly socket 106 extends into the housing 102 and is shaped and adapted to receive the transducer assembly 122, as will be described in further detail below.

[0026] Figure 3 is a cross-sectional view of the ion selective electrode assembly (100) taken along line AA in Figure 2. In this view, the sample input (104) is seen to pass through the housing (102) and exit at the sample output (112), defining a sample pathway (120) within the housing (102). The transducer assembly socket (106) is shown as a threaded cavity and can be seen to terminate in a transducer receiving portion (114). The transducer receiving portion includes a transducer seal (118), which surrounds a test portion (116), which may also be referred to as a sensing aperture. The test portion (116) is the area within the housing (102) where the transducer receiving portion (114) and the sample pathway (120) intersect. When the transducer assembly (122) is mounted within the housing (102), the working portion of the transducer assembly (122) can contact the sample fluid in the sample path (120) at the test portion (116), as will be described in further detail below.

[0027] In the view of Figure 3, sample fluid provided to the sample input (104) can be seen to move horizontally through the housing (102), into the test portion (116), then vertically out of the test portion (116), and then vertically through the housing (102) until it exits at the sample output (112).

[0028] Figures 4 and 5 each show alternative views of ISE assembly (100). In Figure 4, ISE assembly (100) is again shown with transducer assembly (122) removed, and the transducer receiving portion (114) area can be seen to include transducer seal (118) and test portion (116). Figure 4 shows additional detail of housing (102), including contoured portion (103), which may be shaped and adapted to aid in positioning ISE assembly (100) within biological test system (10).

[0029] 6A and 6B each show a perspective view of transducer assembly 122. Transducer assembly 122 includes transducer 126, threaded portion 128, mounting nut 130, and probe 124. Probe 124 terminates in connector 132, which is conductively coupled to transducer 126 within threaded portion 128. When transducer 126 contacts a fluid sample, a voltage is generated and transmitted through probe 124 to connector 132, which is itself adapted to couple to processor 12 when ISE assembly 100 is installed in biological test system 10. The threaded portion (128) houses a portion of the probe (124), which is conductively coupled to the transducer (126) and fits into the transducer receiving portion (114). A mounting nut (130) is secured to the threaded portion (128) and can be grasped with a tool when installing the threaded portion (128), allowing the transducer assembly (122) to be tightly installed within the transducer assembly socket (106).

[0030] 7 shows a perspective view of the transducer (126). The transducer (126) includes a body (127) and a membrane (129). The membrane (129) may be formed from a polymer, glass, crystal, or other suitable membrane material and may be cast or otherwise bonded to the body (127). The body (127) may be formed from a conductive material. For example, in some implementations, the body (127) may be formed from a solid graphite material, and the membrane (129) may be cast directly onto the surface of the body (127).

[0031] The composition and structure of membrane (129) can be varied to produce a transducer capable of measuring various substances, as will be apparent to those skilled in the art in light of this disclosure. For example, the porosity or thickness of membrane (129) can be varied depending on whether a particular membrane is to measure sodium or potassium. In addition to allowing the measurement of a substance, membrane (129) is also flexible, which helps seal sample path (120) when transducer assembly (122) is installed within ISE assembly (100).

[0032] Figure 8 is a cross-sectional view of the ion selective electrode taken along line AA in Figure 2. Figure 8 illustrates both the fully assembled ISE assembly (100) and the sealing function of the membrane (129). In that view, the transducer assembly (122) can be seen within the transducer assembly socket (106). While the threaded portion (128) and the transducer assembly socket (128) are shown as a threaded screw-type assembly, it should be understood that the transducer assembly (122) can be secured within the housing (102) in other ways, such as by friction fit, mechanical latching, spring release latching, etc.

[0033] Below threaded portion (128), transducer (126) can be seen positioned within transducer receiving portion (114) such that transducer seal (118) contacts membrane (129) of transducer (126). ISE assembly (100) can be assembled in the manner shown, for example, by installing transducer (126) within transducer receiving portion (114) and then threading threaded portion (128) into transducer assembly socket (106) by rotating mounting nut (130). As threaded portion (128) is advanced, it contacts the back surface of transducer (126) and presses the back surface of transducer (126) against transducer seal (118). As membrane 129 is pressed against transducer seal 118, it will flex and create a pressure seal with sample path 120. Threaded portion 128 and mounting nut 130 can be adapted (e.g., by varying their size or location) to control the depth to which threaded portion 128 can be advanced, allowing suitable pressure to form the seal but preventing overtightening that could damage membrane 129. In addition to such structural limitations, other pressure-limiting features can also be implemented (such as by including a torque-activated slip feature in mounting nut 130, providing rigid structural contact between transducer seal 118 and a portion of transducer 126, or other features), as will be apparent to those skilled in the art in light of this disclosure.

[0034] As shown in FIG. 8 , when assembled, the membrane (129) portion of the transducer (126) can be seen exposed to the testing portion (116) within the sample path (120). As sample fluid flows through the sample path (120), it will contact the membrane (129), allowing for analysis of the sample fluid. This configuration offers several advantages. For example, the membrane (129) surface is directly integrated with the sample path (120), providing a uniform surface for contacting the sample fluid and preventing carryover contamination or retention of sample fluid between tests. Additionally, the seal between the sample path (120) and the transducer assembly socket (106) is provided by the mechanical force of the threaded portion (128) against the transducer (126), meaning that no adhesives, sealants, or separate sealing features are required. As a result, there is no risk of contamination from the adhesive and of degrading the adhesive or sealant, ultimately causing failure and reducing the shelf life of ISE assembly 100. The pressure seal provided by threaded portion 128 is permanent in nature, allowing for a long shelf life, and can be easily checked or tightened prior to or during use with mounting nut 130.

[0035] In some implementations, the housing (102) and the transducer assembly socket (106) may be formed from a plastic or polymer, while the threaded portion (128) may be a similar material. Such materials may be selected to assist in achieving a seal between the components, preventing overtightening of the transducer (126), avoiding conduction from the transducer (126), or maintaining a seal between the components under various storage conditions during an extended shelf life (e.g., variable temperatures can cause material expansion and contraction for some materials), and such selections will be apparent to those skilled in the art in light of this disclosure.

[0036] As an additional benefit, the transducer 126 can be installed and sealed directly into the transducer receiving portion 114 by installing the threaded portion 128 and tightening the mounting nut 130. Because the membrane 129 is cast directly onto the body 127 and the ISE assembly 100 can be fully assembled without adhesives or other steps, human contact with the membrane 129 can be minimized or avoided entirely. Because contact with the membrane 129 can result in the porous features becoming clogged with debris, minimizing such contact and providing a simplified assembly of the ISE assembly 100 as illustrated in FIG. 8 can reduce errors and improve the accuracy of test results. As an additional benefit, such an implementation provides a solid transducer 126 and membrane 129, which can provide advantages in the simplicity, reliability, durability, ease of assembly, and ease of use of the ISE assembly 100. The frequency and extent of maintenance required for the ISE assembly (100) may also be reduced because there is no need to inspect adhesives or seals or clean or flush carryover contamination from the cavity, reducing the need to fully inspect the sample path compared to an ISE that uses a membrane-coated sample path.

[0037] The variable mounting of the ISE assembly (100) will provide a variable contact surface area between the membrane (129) and the sample path (120). For example, some mountings may provide a variable contact surface area between the membrane (129) and the sample path (120) as desired. 2 , allowing the overall size of the ISE assembly (100) to be reduced. Accurate measurements using such a contact surface area are possible due to factors such as the solid design of the transducer (126), the position of the membrane (129) within the sample path (120), the absence of adhesives, solvents, sealants, or other contaminants that may damage the membrane (129), and other factors. Measurement response times can also be reduced to one second or less and can be performed using smaller amounts of sample fluid due in part to the reduced contact surface area and the accuracy with which the membrane (129) can provide results.

[0038] As discussed, the ISE assembly (100) can be configured to test the concentration of a particular substance (e.g., sodium, potassium, chloride) by varying the properties of the membrane (129). In some implementations, each ISE assembly (100) can test a single substance, such that the sample path (18) of FIG. 1 can pass through multiple ISE assemblies (100), with each ISE assembly (100) configured to provide a different measurement. The sample path (18) can pass through the ISE assemblies (100) sequentially or can branch and pass through the ISE assemblies (100) in parallel. Other features, variations, and advantages of the ISE assembly (100) also exist and will be apparent to those skilled in the art in light of this disclosure, and some such variations are disclosed and described in further detail below.

[0039] II. Exemplary Reference Electrodes

[0040] As described, an ISE, such as the ISE assembly (100), measures the concentration of a substance in a sample fluid based on the voltage generated during contact. Interpretation of the voltage measurement provided by the ISE assembly (100) typically requires a reference voltage. In some implementations, this reference voltage may be provided by a reference electrode. FIG. 9 shows a schematic diagram of an exemplary reference electrode (200) implemented and assembled using some of the features of the ISE assembly (100). The reference electrode (200) differs from other ISEs in several ways, including providing a constant voltage measurement during testing and the sensing element of the reference electrode (200) not directly contacting the sample path (18).

[0041] As shown in FIG. 9, the reference electrode (200) includes a housing (202) with a sample input (204). A probe (216) extends partially from the housing (202) and includes a connector (220) at its distal end, which couples to the processor (12) and provides data or a signal indicative of the measured voltage. FIG. 10 is a schematic diagram illustrating the components within the housing (202) of the reference electrode (200). The sample input (204) receives the sample fluid when the reference electrode (200) is placed in the sample path (18). The sample fluid travels through the sample path (212) and exits the reference electrode (200) via a sample output (not shown), similar to that described in the context of the ISE assembly (100). The sample fluid flowing through the sample path (212) will contact the transducer (215). The transducer (215) is sealed to the sample path (212) by a threaded portion (214) that is advanced into the socket (210), similar to that described in the context of the ISE assembly (100).

[0042] The housing (202) also includes a reservoir (206), which may be filled with a conductive electrolyte liquid and sealed within the housing (202) by a cap (208). The cap (208) may be pressure-sealed onto the housing (202) by screws or other fasteners that attach the cap (208) to the socket (210) or threaded portion (214). A probe tip (218) at the proximal end of the probe (216) is adjacent to but in contact with the transducer (215). When assembled in this manner, the reference electrode (200) may provide a constant reference voltage to the processor (12) via the connector (220) when the sample fluid contacts the transducer (215). When used in a biological test system (10), the reference electrode (200) may be paired with one or more ISE assemblies (100) (e.g., in series or in parallel along the sample path (18)) to provide a reference voltage that can be used to determine the ion concentration in the sample fluid.

[0043] III. Exemplary Parallel Test Assembly

[0044] The following examples relate to various non-exhaustive ways in which the teachings herein may be combined or applied. It should be understood that the following examples are not intended to limit the scope of any claims that may be presented at any time in this application or in a subsequent application thereto. No disclaimer is intended. The following examples are provided solely for illustrative purposes. It is contemplated that the various teachings herein may be arranged and applied in numerous other ways. It is also contemplated that some variations may omit certain features referred to in the examples below. Accordingly, none of the aspects or features referred to below should be deemed essential at a later date by the inventor or his successors in title unless expressly indicated otherwise. If any claims including additional features beyond those referred to below are presented in this application or in a subsequent application related to this application, those additional features shall not be deemed added for any reasons related to patentability.

[0045] Example 1

[0046] 1. An ion-selective electrode comprising: (a) a housing comprising: (i) a sample path passing through the housing, the sample path comprising a sensing opening; (ii) an electrode socket defined by an opening in the housing, the electrode socket comprising a cavity in the housing accessible through the opening; and (iii) a transducer positioned within the receiver cavity and connected to the sample path through the sensing opening; (b) a sensor comprising a membrane structure and a membrane, (i) the membrane structure configured to position the membrane at the sensing opening when the sensor is placed within the transducer receiving portion such that a liquid solution passing through the sample path contacts the membrane, and (ii) the membrane is configured to generate an electric potential based on contact with the liquid solution; (c) a socket plug adapted to fit into the electrode socket and bias the membrane against the sensing opening; and (d) an electrical contact socket passing through the plug and coupled to the sensor, the electrical contact being usable to measure an electric potential from outside the housing.

[0047] Example 2

[0048] 10. The ion selective electrode of claim 1, wherein the electrical contacts include an internal contact and an external contact, and (i) the socket plug is configured to position the internal contact against the membrane structure when mated with the electrode socket, and (ii) the external contact extends from the electrical contact to an exterior of the housing, and (ii) the internal contact is coupled to the external contact and configured to transfer an electrical potential from the membrane structure to the external contact.

[0049] Example 3

[0050] 3. The ion selective electrode of any one or more of Examples 1-2, wherein the socket plug comprises threads configured to couple the socket plug and the electrode socket and bias the membrane against the sensing aperture when the socket plug is advanced into the electrode socket.

[0051] Example 4

[0052] 4. The ion selective electrode of Example 3, wherein the socket plug is configured such that when threaded into the electrode socket, it contacts the membrane structure, causing the membrane to compress against the sensing aperture and form a fluid-tight seal between the membrane and the sensing aperture.

[0053] Example 5

[0054] 5. The ion-selective electrode of example 4, wherein the socket plug is configured, when threaded into the electrode socket, to form a fluid-tight seal between the socket plug and the electrode socket.

[0055] Example 6

[0056] The ion selective electrode of any one or more of Examples 1-5, wherein the membrane structure comprises conductive graphite.

[0057] Example 7

[0058] The ion-selective electrode of Example 6, wherein the membrane comprises a solid ion-selective membrane.

[0059] Example 8

[0060] An ion-selective electrode as described in Example 7, wherein the solid ion-selective membrane is cast directly onto conductive graphite.

[0061] Example 9

[0062] The ion selective electrode of any one or more of Examples 1-8, wherein the contact surface area defined by the portion of the membrane exposed to the sample pathway is about 0.006 square inches.

[0063] Example 10

[0064] The ion selective electrode of any one or more of Examples 1-9, wherein the sensor self-seals to the sensing aperture when the electrical contact is mated with the electrode socket.

[0065] Example 11

[0066] The ion selective electrode of Example 11, wherein the sensor and sensing aperture are free of any other sealing features or adhesives.

[0067] Example 12

[0068] The ion selective electrode of any one or more of Examples 1-11, wherein the sensor consists essentially of a membrane structure and a membrane.

[0069] Example 13

[0070] The ion selective electrode of any one or more of Examples 1-12, wherein the membrane is configured to generate an electric potential based on an ion concentration of an ion in the liquid solution, the ion being selected from the group consisting of potassium, sodium, and chloride.

[0071] Example 14

[0072] A method of assembling an ion selective electrode, the method comprising: (a) fabricating a housing having dimensions selected to suit a desired application, the housing comprising: (i) a sample path passing through the housing, the sample path comprising a sensing opening; (ii) an electrode socket defined by an opening in the housing, the electrode socket comprising a cavity in the housing accessible from the opening; and (iii) a transducer positioned within a receiver cavity and connected to the sample path through the sensing opening; (b) creating a membrane structure having dimensions selected to fit within the transducer receiver; A method comprising: producing a sensor by casting a membrane directly onto a membrane structure, wherein (i) the membrane structure is configured to position the membrane at a sensing aperture such that when the sensor is coupled to a transducer receiver, a liquid solution passing through a sample path contacts the membrane, and (ii) the membrane is configured to generate an electric potential based on contact with the liquid solution; (c) placing the sensor on the transducer receiver; (d) advancing a socket plug into an electrode socket to bias the membrane against the sensing aperture; and (e) coupling electrical contacts to the sensor, the electrical contacts usable to measure the electric potential from outside the housing.

[0073] Example 15

[0074] 15. The method of example 14, further comprising configuring the membrane to generate an electrical potential based on an ion concentration of an ion in the liquid solution, the ion being selected from the group consisting of potassium, sodium, and chloride.

[0075] Example 16

[0076] The method of any one or more of Examples 14-15, wherein the membrane structure comprises conductive graphite and the membrane comprises a solid ion-selective membrane, and further comprising preventing any direct physical contact with the membrane after sensor generation until the sensor is placed within the transducer-receiver.

[0077] Example 17

[0078] The method of any one or more of Examples 14-15, further comprising: mating the electrical contact with the electrode socket by threading the socket plug into the electrode socket, thereby forming (a) a liquid-tight seal between the socket plug and the electrode socket; and (b) a liquid-tight seal between the membrane and the sensing opening.

[0079] Example 18

[0080] 18. The method of example 17, further comprising producing a sensor and forming a liquid-impermeable seal between the membrane and the sensing opening without including any adhesive within the sensor and the sensing opening and without including any other sealing features.

[0081] Example 19

[0082] a reference electrode comprising: (a) a housing comprising: (i) a sample path passing through the housing, the sample path having a sensing opening; (ii) a reservoir within the housing and a cap adapted to seal the container; (iii) an electrode socket within the container; and (iv) a transducer receiver positioned in the electrode socket and connected to the sample path through the sensing opening; (b) a sensor comprising a membrane structure and a membrane; (i) the membrane structure configured to position the membrane at the sensing opening such that a liquid solution passing through the sample path contacts the membrane when the sensor is placed within the transducer receiver; and (ii) the membrane configured to generate an electric potential based on contact with the liquid solution; (c) a socket plug adapted to fit into the electrode socket and bias the membrane against the sensing opening; and (d) an electrical contact passing through the housing into the reservoir through the electrode socket such that a proximal tip of the electrical contact is adjacent to the sensor socket plug, the electrical contact being configured to transmit an electric potential from the liquid at the proximal tip to a distal tip outside the housing.

[0083] Example 20

[0084] 20. The reference electrode of Example 19, wherein the socket plug comprises threads configured to couple the socket plug to the electrode socket and bias the membrane against the sensing aperture when the socket plug is advanced into the electrode socket.

[0085] Example 21

[0086] 21. The reference electrode of Example 20, wherein the socket plug is configured such that, when threaded into the electrode socket, it makes contact with the membrane structure, causing the membrane to compress against the sensing aperture and form a liquid-tight seal between the membrane and the sensing aperture.

[0087] (Miscellaneous)

[0088] It should be understood that any of the examples described herein may include various other features in addition to or in place of those described above. By way of example only, any of the examples described herein may also include one or more of the various features disclosed in any of the various references incorporated herein by reference.

[0089] It should be understood that any one or more of the teachings, expressions, embodiments, examples, etc. described herein may be combined with any one or more of the other teachings, expressions, embodiments, examples, etc. described herein. The teachings, expressions, embodiments, examples, etc. described above should therefore not be viewed in isolation from one another. Various suitable ways in which the teachings herein may be combined will be readily apparent to those skilled in the art in light of the teachings herein. Such modifications and variations are intended to be included within the scope of the claims.

[0090] It should be understood that any patent, publication, or other disclosure material that is deemed to be incorporated herein by reference, in whole or in part, is incorporated herein only to the extent that the incorporated material does not contradict existing definitions, language, or other disclosure material set forth in this disclosure. Thus, to the extent necessary, the disclosure as expressly set forth herein supersedes any conflicting material incorporated herein by reference. Any material, or portion thereof, that is deemed to be incorporated herein by reference but that contradicts existing definitions, language, or other disclosure material set forth herein will be incorporated only to the extent that it does not create any contradiction between the incorporated material and the existing disclosure material.

[0091] While various versions of the present invention have been shown and described, further adaptations of the methods and systems described herein may be accomplished by appropriate modifications by those skilled in the art without departing from the scope of the present invention. Some of such potential modifications have been mentioned; others will be apparent to those skilled in the art. For example, the embodiments, versions, geometries, materials, dimensions, proportions, steps, and equivalents discussed above are illustrative and not required. Thus, the scope of the present invention should be considered in light of the following claims and is understood not to be limited to the details of structure and operation shown and described in the specification and drawings.

Claims

[Claim 1] The invention described in this specification.

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