Solid-state ion-selective electrodes

Abstract

To provide solid state ion selective electrodes.SOLUTION: An ion selective electrode (ISE) assembly may be installed within a sample path of a biological testing system to measure ion concentration within a sample fluid flowing through the sample path. A transducer membrane is placed within a housing and positioned to contact the sample path. A threaded portion is advanced into a socket of the housing, and forces the membrane against a sealing portion of the sample path to prevent retention of the sample fluid within the housing after testing. Sealing may be accomplished without adhesives or sealants, and instead relies upon mechanical pressure of the threaded portion. Another implementation includes a reference measuring electrode and several ion measuring electrodes combined into a single housing. Another implementation includes the reference measuring electrode and several ion measuring electrodes combined into a cartridge that includes a sample well instead of the sample path.SELECTED DRAWING: None

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) 1. A parallel testing assembly, comprising: (a) a housing, the housing comprising: (i) a sample pathway passing through the housing, the sample pathway comprising an inlet fluid divider and an outlet fluid combiner, the fluid divider adapted to divide fluid into two or more pathways, and the fluid combiner adapted to combine fluid from the two or more pathways into a single pathway; (ii) two or more electrode sockets defined by openings in the housing, each electrode socket comprising a cavity in the housing accessible through the opening connected to the two or more pathways; (iii) a reservoir within the housing that is open to a reference electrode socket among the two or more electrode sockets; a housing comprising: (b) a reference electrode positioned within the reference electrode socket, the reference electrode sealing a reference membrane of a reference transducer to a reference path of the two or more paths; (c) a reference probe with a proximal end positioned within the reservoir adjacent the reference electrode and a distal end positioned outside the housing; (d) one or more ion-selective electrodes positioned within said two or more electrode sockets; Equipped with A parallel testing assembly, wherein each of the ion selective electrodes seals a transducer to a path of the two or more paths. (Item 2) The sample path includes: (a) receiving a sample fluid at the inlet side; (b) redirecting a portion of the sample fluid to each of the two or more paths in the sample distributor; (c) placing a portion of the sample fluid in contact with the reference transducer and each transducer of the one or more ion selective electrodes; (c) receiving the portion of the sample fluid at the sample junction and transporting the sample fluid out of the housing at the output side; Item 1. The parallel testing assembly of item 1, adapted to perform (Item 3) (a) the reference transducer is configured to generate a reference potential; (b) a first transducer of the one or more ion selective electrodes is configured to generate an electrical potential indicative of sodium concentration; (c) a second transducer of the one or more ion selective electrodes is configured to generate an electrical potential indicative of potassium concentration; (d) a third transducer of the one or more ion selective electrodes is configured to generate a potential indicative of chloride concentration. (Item 4) (a) the reference electrode is threaded into the reference electrode socket, sealing the reference membrane to the reference passage; (b) each of the one or more ion-selective electrodes is threaded into a respective one of the two or more electrode sockets, sealing a respective membrane to a respective one of the two or more pathways. (Item 5) 1. A cartridge assembly, the cartridge assembly comprising: (a) a housing adapted to fit within a cartridge-receiving portion of a biological testing system; (b) a sample well defined by a recess in the top surface of the housing; (c) a reference transducer positioned within the sample well and embedded within the housing, the reference transducer configured to generate a reference potential based on contact with sample fluid in the sample well; and (d) a reservoir of reference fluid within the housing and in contact with the reference transducer, the reference potential being generated within the reservoir; (e) one or more transducers positioned within the sample well and embedded within the housing, each of the one or more transducers configured to generate an electrical potential upon contact with the sample fluid in the sample well; (f) a set of connectors on the bottom surface of the housing; Equipped with (i) a reference connector of the connector set enters the reservoir from outside the housing, whereby a proximal end of the reference connector is adjacent to the reference transducer and a distal end of the reference connector is positioned outside the housing; (ii) a proximal end of one or more connectors of the set of connectors is coupled to the one or more transducers within the housing, and a distal end of the one or more connectors is positioned outside the housing; The set of connectors is configured to transmit the reference potential and the potentials of the one or more transducers to a processor of the biological test system when the cartridge assembly is placed in the cartridge receiving portion. (Item 6) The one or more transducers (a) a first transducer configured to generate an electrical potential indicative of a sodium concentration in the sample fluid; (b) a first transducer configured to generate an electrical potential indicative of the potassium concentration in the sample fluid; (c) a first transducer configured to generate an electrical potential indicative of chloride concentration in the sample fluid; and Item 6. The cartridge assembly of item 5, comprising: (Item 7) Item 6. The cartridge assembly of item 5, wherein the sample well is adapted to retain the sample fluid due to the effect of surface tension. (Item 8) Item 6. The cartridge assembly of item 5, further comprising a cover adapted to seal sample fluid in the sample well when placed on the cartridge assembly. (Item 9) Item 6. The cartridge assembly of item 5, wherein the housing is about 0.5 cm to about 2 cm long, about 0.35 cm to about 1.5 cm wide, and about 0.1 cm to about 0.4 cm deep. 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.

[0016] [Figure 11] FIG. 11 is a perspective view of an exemplary parallel testing assembly.

[0017] [Figure 12] FIG. 12 is an exploded perspective view of the parallel testing assembly of FIG.

[0018] [Figure 13] FIG. 13 is a schematic diagram of the parallel testing assembly of FIG. 11 with portions of the exemplary housing removed to show internal details.

[0019] [Figure 14] FIG. 14 is a cross-sectional view of the parallel testing assembly along line BB of FIG. 11 with the electrode assembly removed.

[0020] [Figure 15] FIG. 15 is a flow diagram illustrating the flow of liquid through the sample path of the parallel test assembly.

[0021] [Figure 16] FIG. 16 is a perspective view of an exemplary cartridge assembly.

[0022] [Figure 17] 17 is a bottom view of the cartridge assembly of FIG. 16. FIG.

[0023] [Figure 18] FIG. 18 is a schematic diagram of a cross-sectional view of the cartridge assembly taken along line CC in FIG.

[0024] [Figure 19] FIG. 19 is a schematic diagram of an alternative exemplary biological test system that can be used with the cartridge assembly of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] I. Exemplary Ion-Selective Electrode Assemblies

[0030] 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.

[0031] 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).

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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).

[0037] 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).

[0038] 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).

[0039] 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).

[0040] 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).

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] II. Exemplary Reference Electrodes

[0049] 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).

[0050] 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).

[0051] 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 a screw or other fastener that attaches 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 does not contact, 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.

[0052] III. Exemplary Parallel Test Assembly

[0053] As described, the biological test system (10) may include several electrode assemblies (e.g., a reference electrode (200), one or more ISE assemblies (100)). In implementations of the biological test system (10) that may be advantageous for biological testing, dedicated ISE assemblies (100) may be included for measuring the concentrations of several specific ions, such as sodium, potassium, and chloride. Some implementations of such systems may include three ISE assemblies (100), each with a dedicated measurement configuration, along with a reference electrode (200) positioned sequentially along the sample path (18).

[0054] In some implementations of the biological test system (10), the sensing element (20) is located within the sample path (18) and may be implemented as a single assembly containing multiple capabilities. By way of example, FIG. 11 shows a perspective view of an exemplary parallel test assembly (300). The parallel test assembly (300) receives and tests sample fluids similar to those described in the context of the ISE assembly (100) and reference electrode (200), provided that the sample fluid flows into the parallel test assembly (300), the flow along the sample path contacts the sensing element along the sample path, and then exits the parallel test assembly (300).

[0055] However, in using parallel test assemblies 300, multiple sensing capabilities can be provided and sample fluid measurements can be performed in parallel, within substantially the same time frame, rather than sequentially flowing through multiple ISE assemblies 100. As a result, the overall testing time of a fluid sample can be reduced.

[0056] The parallel test assembly (300) of Figure 11 includes a housing (302) that includes a sample input (312) that receives and transmits a sample fluid onto a sample path that passes through the housing (302). The sample fluid passing through the parallel test assembly (300) can be tested in parallel, rather than sequentially, by the reference electrode (304), first electrode (306), second electrode (308), and third electrode (310). Thus, in an implementation of the biological test system (10) that tests the concentrations of three substances (e.g., sodium, potassium, and chloride) in a sample fluid, the parallel test assembly (300) can be used in place of four separate assemblies, and advantageously, the parallel measurement can also increase sample fluid throughput and testing speed.

[0057] The parallel test assembly (300) includes several components with similar features and functions as those used in the ISE assembly (100), but their arrangement is different in order to fit within a single housing (302). To illustrate, FIG. 12 shows an exploded perspective view of the parallel test assembly (300). The reference electrode (304) is shown extending from the cap (320) and from within the reservoir (318) within the housing (302). As explained in the context of the reference electrode (200), the reservoir (318) may be filled with a conductive electrolyte fluid to aid in measuring a reference voltage. Once filled, the reservoir is sealed by the cap (320), and the reference electrode (304) is threaded through the cap (320) such that the probe tip (322) is positioned within the reservoir (318) in proximity to, but not in contact with, the reference transducer (316). The reference transducer (316), similar to the transducer (215), is inserted into the reference socket (336) and is pressure-sealed within the housing (302) by being pressed onto the threaded portion (314) which is advanced into the reference socket (336).

[0058] The first electrode (306) includes a threaded portion (324) similar to the transducer (126) and threaded portion (128) of the ISE assembly (100), and a transducer (326). The transducer (326) is placed into a first electrode socket (338) and pressure-sealed within the housing (302) by advancing the threaded portion (324) into the first electrode socket (338). Similar to the transducer assembly (122), a voltage generated in the transducer (326) is conductively communicated to the processor (12) along the length of the electrode (306). The second electrode (308) includes a threaded portion (332) that can be press-fit into a second electrode socket (340), and a transducer (334), each component having similar function and characteristics to the corresponding component of the first electrode (306). The third electrode (310) includes a threaded portion (328) that can be press-fit into the third electrode socket (342) and a transducer (330), each component having similar functions and characteristics to the corresponding component of the first electrode (306).

[0059] When arranged as shown, the parallel test assembly (300) can be configured such that each electrode provides a different measurement of the sample fluid. By way of example, the first electrode (304) can be configured to measure the sodium content in the sample fluid (e.g., based on the membrane properties of the transducer (326)), the second electrode (308) can be configured to measure the potassium content in the sample fluid, and the third electrode (310) can be configured to measure the chloride content in the sample fluid. By using the reference electrode (304) to provide a reference voltage measurement for such an arrangement, the parallel test assembly (300) replaces several separate components that may be sequentially arranged within the biological test system (10), while sharing the same advantages as the ISE assembly (100) and reference electrode (200) (e.g., no requirement for pressure seals, adhesives, sealants, or solvents for the manifold (129), increased durability and shelf life, and other improvements described above).

[0060] A simulated view of the electrode placement within the housing of a fully assembled parallel testing assembly (300) can be seen in Figure 13, which shows a schematic diagram of the parallel testing assembly (300) with some portions omitted for visibility. In that view, the threaded portion (324) of the first electrode (306) can be seen advanced into the first electrode socket (338), the threaded portion (332) of the second electrode (308) can be seen advanced into the second electrode socket (340), and the threaded portion (328) of the third electrode (310) can be seen advanced into the third electrode socket (342). Similarly, the threaded portion (314) of the reference electrode (304) can be seen advanced into the reference socket (336). Using this arrangement, the reference transducer (316), and the transducer (326) of the first electrode (306), the transducer (334) of the second electrode (308), and the transducer (330) of the third electrode (310) are all positioned and sealed within the housing (302) in close proximity to the location of the sample input (312) of the parallel test assembly (300). The location of the probe tip (322) relative to the reservoir (318) and the reference transducer (316) within the reservoir (318) is also visible in FIG.

[0061] One structure not visible in Figure 13 is the structure of the channels that route the sample fluid to each of the transducers so that the fluid can be tested without any crosstalk between the transducers (e.g., erroneous detection of voltage or other properties). That structure is shown, in part, in Figure 14, which is a cross-sectional view of the parallel test assembly (300) along line BB in Figure 11, with the first electrode (306), second electrode (308), and third electrode (310) removed from the housing (302). In that view, the internal structure of the housing (302) is visible, and the sample input (312) can be seen to pass through the housing (302), exit via the sample output (344), and connect to a set of channels that define the sample pathway (346). A sample path (346) is defined within housing (302) such that the sample fluid flow splits and flows to transducer receiving portions (347) of each threaded portion within housing (302) to contact transducers positioned within respective transducer receiving portions (347), similarly as disclosed in the context of transducer receiving portion (114) of ISE assembly (100). After passing through each transducer receiving portion (347), the split flows of sample fluid recombine and exit housing (302) via sample output (344).

[0062] Additionally, to illustrate the sample path (346) defined by the structure of the housing (302), Figure 15 shows a flow diagram illustrating the flow of liquid through the parallel test assembly (300). The liquid flow begins at the sample input (312) and proceeds in the direction indicated by the arrows. Upon reaching the sample divider (354), the liquid flow splits into four separate channels, each a partial sample input (348), and is similarly received by a respective test portion (116), as described in the context of the test portion (116) of the ISE assembly (100).

[0063] With respect to the image shown in Figure 15, a portion of the fluid can be seen to proceed along partial sample input (348) to the right into testing portion (350a), then flow through testing portion (350a) into partial sample output (352). Fluid from partial sample output (352) is then received at sample junction (356), where the split sample flows are recombined, then exit via sample output (344). Similarly, a portion of the fluid proceeds upward from sample junction (354) into testing portion (350d), then flows downward through testing portion (350d) toward sample junction (356), where it recombines with the other sample fluid and exits via sample output (344). As will be apparent, a portion of the fluid also travels left from sample distributor (354) into testing portion (350c) and then flows through testing portion (350c) toward sample junction (356) where it is recombined with the other sample fluids. Finally, a portion of the fluid also travels downward from sample distributor (354) into testing portion (350b) and then flows back through testing portion (350b) toward sample junction (356) where it is recombined with the other sample fluids. The splitting and merging of the sample fluids can be accomplished by using the shape and contours of the structures defining sample path (346), by pressurization of the sample fluid input, or both, as will be apparent to those skilled in the art in light of this disclosure.

[0064] As may be apparent, each of the test portions shown in FIG. 15 corresponds to a transducer receiving portion, such as transducer receiving portion 347, with an electrode located therein. For example, test portion 350c corresponds to first electrode 306 and contacts transducer 326, test portion 350a corresponds to second electrode 308 and contacts transducer 334, test portion 350b corresponds to third electrode 310 and contacts transducer 330, and test portion 350d corresponds to reference electrode 304 and contacts reference transducer 316. In this manner, each transducer may be seen to be in contact with the sample fluid flowing through sample channel 346 while also being isolated from one another to prevent electrical crosstalk.

[0065] The parallel test assembly (300) can be advantageously implemented not only for the reasons given in the context of the ISE assembly (100) and reference electrode (200), but also for the additional benefits of parallel testing and effectively increased fluid sample throughput. For example, when the biological test system (10) includes the parallel test assembly (300), the overall length of the sample path (18) can be reduced. To illustrate with reference to FIG. 15 , the longest distance any portion of the sample fluid can travel through the sample path (346) is approximately one-quarter of the longest distance the sample fluid can travel through four sequentially arranged assemblies, as the sample fluid splits and travels in parallel along each branch. By reducing the overall length of the sample path (18), the biological test system (10) can test a sample, perform any in-test maintenance, and then test a second sample more quickly. The parallel test assembly (300) offers additional advantages from a usability and maintenance standpoint, as a single assembly can be easier to install and replace than multiple assemblies. Other features, advantages, and modifications of parallel test assembly (300) exist and will be apparent to those skilled in the art in light of this disclosure.

[0066] IV. Exemplary Cartridge Assembly

[0067] As discussed, biological test system 10 provides a sample path 18 through which sample fluid flows and contacts one or more sensing elements 20. Such systems can be advantageously used with assemblies such as ISE assembly 100, reference electrode 200, and parallel assembly 300, although other types of biological test systems can also be implemented based on the present disclosure. By way of example, some implementations of biological test systems and ISE assemblies may not require a flow path, which may provide certain advantages.

[0068] By way of example, Figure 16 is a perspective view of an exemplary cartridge assembly (400). Cartridge assembly (400) includes a body (402) that is flat and includes chamfered edges and rounded corners. Depending on the particular implementation, body (402) may be about 0.5 cm to about 2 cm long, about 0.35 cm to about 1.5 cm wide, and about 0.1 cm to about 0.4 cm deep. Body (402) is sized and shaped so that it can be used as a portable cartridge-type assembly that can be inserted into and removed from a biological test system (22), such as the one shown in Figure 19. Biological test system (22) includes processor (12) and also includes cartridge-receiving portion (24). Cartridge-receiving portion (24) is configured to receive and conductively couple to cartridge assembly (400), provide any necessary electrical output during testing of a sample fluid provided to cartridge assembly (400), receive test output (e.g., data indicative of a voltage, an electrical signal, or other information), and provide the test output to processor (12) for processing and interpretation, as described in the context of Figure 1. The size and shape of cartridge assembly (400) can be varied based on the characteristics of cartridge-receiving portion (24), based on usability factors (e.g., particularly small sizes may be difficult to handle and place within cartridge-receiving portion (400)), and based on other factors, as will be apparent to those skilled in the art in light of this disclosure.

[0069] Cartridge (400) includes a sample well (410) as a shallow recess recessed into body (402). Sample well (410) includes a reference transducer (404), a first transducer (406), a second transducer (408), and a third transducer (412). Each transducer in sample well (410) functions similarly to transducer (126) of ISE assembly (100) in that it generates a voltage in response to contact with a sample fluid, and the voltage is either a reference voltage or a voltage indicative of the concentration of a substance in the sample fluid, depending on the type and characteristics of the transducer (e.g., variations in the properties of the transducer's membrane, as described in the context of membrane (129)).

[0070] When using cartridge assembly 400, liquid may be placed directly into and retained within sample well 410 (e.g., by the effects of surface tension, by the application of a cover or seal over sample well 410, or both). When cartridge assembly 400 is not connected to biological test system 22, no analysis of the sample is performed. However, when cartridge assembly 400 is coupled to cartridge receiving portion 24, the transducer will operate and sense and transmit information related to the resulting voltage to processor 12, as described.

[0071] Transmission of voltage information to the processor is accomplished by a set of connectors on the underside of body (402), as can be seen in FIG. 17. In that view, first connector (414), second connector (420), and third connector (422) can be seen extending from the underside of body (402) below sample well (410). Each of the connectors is positioned to conductively couple to a corresponding transducer when inserted and to conductively couple with cartridge receiver (24) and processor (12). Reservoir (418) can also be seen with reference connector (416) extending therefrom in an arrangement similar to reservoir (206) and probe (216) (e.g., reference connector (416) extends into reservoir (418), which can be filled with a conductive fluid, with a proximal tip positioned adjacent to, but not in contact with, reference transducer (404). With such an arrangement, each transducer is embedded within the body (402) and coupled to a corresponding connector on the underside of the transducer.

[0072] Figure 18 is a schematic diagram showing an example of such an arrangement. In that view, which simulates a cross-section along line CC in Figure 18, the sample well (410) can be seen extending into the body (402). The second transducer (408) is visible embedded within the body (402), and the second connector (420) can be seen to contact the underside of the second transducer (408) and extend outward from the body (402) to mate with the cartridge receiver (24) when the cartridge assembly (400) is inserted. The reference transducer (404) can also be seen embedded within the body (402). The underside of the reference transducer (404) will be open to the reservoir (418) and will contact the fluid placed therein. The reference connector (416) extends through the wall of the reservoir (418) and its proximal end is positioned adjacent to the underside of the reference transducer (404) but separated by a distance (424).

[0073] Cartridge assembly (400) shares some similarities with parallel test assembly (300) in that sample well (410) contains four transducers, which can support a configuration including a reference measurement transducer, a sodium concentration transducer, a potassium concentration transducer, and a chloride concentration transducer. However, cartridge assembly (400) lacks a sample path or fluid flowing through the assembly; instead, fluid is received within sample well (410). Implementations lacking a sample path can be advantageous by reducing the need to pressurize or move sample fluid, reducing the need to clean and rinse sample path channels, and preventing carryover contamination between samples (e.g., when cartridge assembly (400) is discarded or cleaned after use).

[0074] Advantages of cartridge assembly 400 include that it is suitable for use in a clinical setting and that it can be subsequently disposed of or cleaned and reused. By way of example, a physician providing treatment directly to a patient can prepare cartridge assembly 400 by removing it from its packaging, removing the sticker or seal, and exposing sample well 410. A patient biological sample (e.g., a drop of blood, etc.) can be collected and dispensed directly into sample well 410, or collected and prepared separately (e.g., by adding or mixing with reagents, solvents, and other substances) and dispensed directly into sample well 410. Cartridge assembly 400 can then be prepared for transfer by sealing sample well 410 to prevent the sample from spilling or becoming contaminated during transfer. Cartridge assembly 400 can then be transported to the location of biological testing system 22, which may be in the same building or facility as the physician, or may be remotely located to provide services to several healthcare providers. Cartridge assembly 400 can be inserted into cartridge receiving portion 24, and results can be captured by processor 12, stored, displayed, or transmitted to a recipient (e.g., by providing test results via a website, web interface, electronic message, or other communication, etc.). Upon completion of the test, cartridge receiving portion 24 can automatically discard cartridge assembly 400 to prepare cartridge receiving portion 24 for a subsequent cartridge, or it can be manually removed and discarded.

[0075] The biological testing system (22) can advantageously be used in scenarios where samples can be tested quickly as soon as the cartridge assembly (400) is received, while also having lower maintenance requirements and a lower potential for carryover contamination due to the lack of a shared sample path or fluid transfer system.

[0076] (V. Illustrative Combinations)

[0077] 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.

[0078] Example 1

[0079] 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.

[0080] Example 2

[0081] 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.

[0082] Example 3

[0083] 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.

[0084] Example 4

[0085] 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.

[0086] Example 5

[0087] 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.

[0088] Example 6

[0089] The ion selective electrode of any one or more of Examples 1-5, wherein the membrane structure comprises conductive graphite.

[0090] Example 7

[0091] The ion-selective electrode of Example 6, wherein the membrane comprises a solid ion-selective membrane.

[0092] Example 8

[0093] An ion-selective electrode as described in Example 7, wherein the solid ion-selective membrane is cast directly onto conductive graphite.

[0094] Example 9

[0095] 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.

[0096] Example 10

[0097] 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.

[0098] Example 11

[0099] The ion selective electrode of Example 11, wherein the sensor and sensing aperture are free of any other sealing features or adhesives.

[0100] Example 12

[0101] 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.

[0102] Example 13

[0103] 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.

[0104] Example 14

[0105] 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 aperture; (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 a receiver cavity and connected to the sample path through the sensing aperture; and (b) creating a membrane structure having dimensions selected to fit within the transducer receiver cavity. , 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 opening 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 opening; and (e) coupling electrical contacts to the sensor, wherein the electrical contacts can be used to measure the electric potential from outside the housing.

[0106] Example 15

[0107] 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.

[0108] Example 16

[0109] 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.

[0110] Example 17

[0111] 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.

[0112] Example 18

[0113] Example 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.

[0114] Example 19

[0115] 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 reservoir; (iii) an electrode socket within the reservoir; 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 through the electrode socket into the reservoir 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.

[0116] Example 20

[0117] 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.

[0118] Example 21

[0119] 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.

[0120] Example 22

[0121] 1. A parallel test assembly, comprising: (a) a housing comprising: (i) a sample path passing through the housing, the sample path comprising a fluid divider on an inlet side and a fluid combiner on an outlet side, the fluid divider adapted to divide fluid into two or more paths, the fluid combiner adapted to combine fluid from the two or more paths into a single path; (ii) two or more electrode sockets defined by openings in the housing, each electrode socket comprising a cavity in the housing accessible from the openings connected to the two or more paths; and (iii) two or more a housing having a reservoir within the housing that is open to a reference electrode socket of the electrode sockets; (b) a reference electrode positioned within the reference electrode socket and sealing a reference membrane of the reference transducer to a reference path of the two or more paths; (c) a reference probe with a proximal end positioned within the reservoir adjacent to the reference electrode and a distal end positioned outside the housing; and (d) one or more ion-selective electrodes positioned within the two or more electrode sockets, each of the ion-selective electrodes sealing the transducer to the two or more paths.

[0122] Example 23

[0123] A parallel testing assembly as described in Example 22, wherein the sample pathway is adapted to (i) receive sample fluid at the inlet side, (ii) transfer a portion of the sample fluid to each of two or more pathways at the sample distributor, (iii) place a portion of the sample fluid in contact with the reference transducer and each of the one or more ion selective electrodes, and (iv) receive a portion of the sample fluid at the sample junction and transport the sample fluid out of the housing at the output side.

[0124] Example 24

[0125] 24. The parallel testing assembly of any one or more of Examples 22-23, wherein (i) the reference transducer is configured to generate a reference potential; (ii) a first transducer of the one or more ion selective electrodes is configured to generate a potential indicative of a sodium concentration; (iii) a second transducer of the one or more ion selective electrodes is configured to generate a potential indicative of a potassium concentration; and (iv) a third transducer of the one or more ion selective electrodes is configured to generate a potential indicative of a chloride concentration.

[0126] Example 25

[0127] The parallel test assembly of any one or more of Examples 22-24, wherein (i) a reference electrode is threaded into the reference electrode socket, sealing the reference membrane to the reference pathway; and (ii) each of the one or more ion selective electrodes is threaded into a respective electrode socket of the two or more electrode sockets, sealing a respective membrane to a respective pathway of the two or more pathways.

[0128] Example 26

[0129] (b) a sample well defined by a recess in an upper surface of the housing; (c) a reference transducer positioned within the sample well and embedded within the housing, the reference transducer configured to generate a reference potential based on contact with sample fluid in the sample well; (d) a reservoir of reference fluid within the housing and in contact with the reference transducer, the reference potential being generated within the reservoir; and (e) one or more transducers positioned within the sample well and embedded within the housing, each of the one or more transducers configured to generate a reference potential based on contact with sample fluid in the sample well. and (f) a set of connectors on a bottom surface of the housing, wherein (i) a reference connector of the set of connectors passes from outside the housing into the reservoir such that a proximal end of the reference connector is adjacent to the reference transducer and a distal end of the reference connector is positioned outside the housing, and (ii) a proximal end of one or more connectors of the set of connectors is coupled to one or more transducers within the housing and a distal end of the one or more connectors is positioned outside the housing, wherein the set of connectors is configured to transmit the reference potential and the potentials of the one or more transducers to a processor of the biological test system when the cartridge assembly is placed in the cartridge receiving portion.

[0130] Example 27

[0131] 27. The cartridge assembly of Example 26, wherein the one or more transducers include: (i) a first transducer configured to generate a potential indicative of a sodium concentration in the sample fluid; (ii) a first transducer configured to generate a potential indicative of a potassium concentration in the sample fluid; and (iii) a first transducer configured to generate a potential indicative of a chloride concentration in the sample fluid.

[0132] Example 28

[0133] The cartridge assembly of any one or more of Examples 26-27, wherein the sample well is adapted to retain sample fluid due to surface tension effects.

[0134] Example 29

[0135] The cartridge assembly of any one or more of Examples 26-28, further comprising a cover adapted to seal sample fluid in the sample well when placed on the cartridge assembly.

[0136] Example 30

[0137] The cartridge assembly of any one or more of Examples 26-29, wherein the housing is about 0.5 cm to about 2 cm in length, about 0.35 cm to about 1.5 cm in width, and about 0.1 cm to about 0.4 cm in depth.

[0138] (Miscellaneous)

[0139] 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.

[0140] 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.

[0141] 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.

[0142] 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

1. 1. A cartridge assembly, the cartridge assembly comprising: (a) a housing adapted to fit within a cartridge-receiving portion of a biological testing system; (b) a sample well defined by a recess in a top surface of the housing configured to receive a sample fluid having ions; (c) a reference transducer positioned within the sample well and embedded within the housing, the reference transducer configured to have a reference potential when the reference transducer contacts the sample fluid in the sample well; and (d) a reservoir of reference fluid within the housing and in contact with the reference transducer, the reference potential being generated within the reservoir; (e) one or more transducers positioned within the sample well and embedded within the housing, each of the one or more transducers configured to have an electrical potential based on an ion concentration of the sample fluid when the one or more transducers contact the sample fluid in the sample well; (f) a set of connectors on the bottom surface of the housing; Equipped with (i) a reference connector of the connector set enters the reservoir from outside the housing, whereby a proximal end of the reference connector is adjacent to the reference transducer and a distal end of the reference connector is positioned outside the housing; (ii) a proximal end of one or more connectors of the set of connectors is coupled to the one or more transducers within the housing, and a distal end of the one or more connectors is positioned outside the housing; A cartridge assembly, wherein the set of connectors is configured to transmit the reference potential and the potentials of the one or more transducers to a processor of the biological test system when the cartridge assembly is placed in the cartridge receiving portion.

2. The one or more transducers (a) a first transducer configured to have an electrical potential indicative of the sodium concentration in the sample fluid; (b) a second transducer configured to have an electrical potential indicative of the potassium concentration in the sample fluid; (c) a third transducer configured to have a potential indicative of chloride concentration in the sample fluid; The cartridge assembly of claim 1 , comprising:

3. The cartridge assembly of claim 1 , wherein the sample well is adapted to retain the sample fluid due to surface tension effects.

4. The cartridge assembly of claim 1 , further comprising a cover adapted to seal the sample fluid in the sample well when placed on the cartridge assembly.

5. 2. The cartridge assembly of claim 1, wherein the housing has a length of 0.5 cm to 2 cm, a width of 0.35 cm to 1.5 cm, and a depth of 0.1 cm to 0.4 cm, the depth being measured in a first direction extending from the top surface to the bottom surface, the length being measured in a second direction perpendicular to the first direction, and the width being measured in a third direction perpendicular to the first and second directions.

Images