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 tests related to patient diagnosis and treatment can be performed by analysis of a patient's microorganisms or "germs." Pathogens are microscopic living organisms such as bacteria, fungi, or viruses that can be unicellular or multicellular. Biological samples containing the patient's microorganisms can be taken 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 the treatment of the patient. 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 when compared to analyses using manual operations, and aid in determining the effectiveness of various antimicrobial agents.

[0002] Such biological test systems may include the use of ion selective electrodes to determine the concentration of ions in a biological sample. This may involve pumping the sample fluid through a channel that passes through or near the ion selective electrodes such 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, causing subsequent analysis of other samples to be 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 through the housing, the sample pathway comprising an inlet fluid divider and an outlet fluid combiner, the fluid divider adapted to split 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 openings 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 at the sample distributor; (c) placing a portion of the sample fluid in contact with the reference transducer and each of the one or more ion selective electrodes; (c) receiving the portion of the sample fluid at the sample junction and transferring the sample fluid out of the housing at the output side; 2. The parallel testing assembly of claim 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 a sodium concentration; (c) a second transducer of the one or more ion selective electrodes configured to generate an electrical potential indicative of a potassium concentration; (d) a third transducer of the one or more ion selective electrodes is configured to generate an electrical 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 to seal a respective membrane to a respective one of the two or more pathways. (Item 5) 1. A 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; and (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 a 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; 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 an electrical potential upon contact with the sample fluid in the sample well; (f) a set of connectors on a bottom surface of the housing; and Equipped with (i) a reference connector of the connector set extends into the reservoir from outside the housing, 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; (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 are 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 within the cartridge receiving portion. (Item 6) The one or more transducers include: (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 a potassium concentration in the sample fluid; (c) a first transducer configured to generate an electrical potential indicative of a chloride concentration in the sample fluid; and 6. The cartridge assembly of item 5, comprising: (Item 7) 6. The cartridge assembly of claim 5, wherein the sample well is adapted to retain the sample fluid due to surface tension effects. (Item 8) 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) 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 numbers identify the same elements and in which: [Brief description of the drawings]

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

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

[0007] [Diagram 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] [Diagram 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 taken along line AA in FIG. 2 of an ion selective electrode assembly 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 with internal details shown.

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

[0017] [Figure 12] 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 along line BB of FIG. 11 of the parallel testing assembly with the electrode assembly removed.

[0020] [Figure 15] FIG. 15 is a flow diagram illustrating the flow of liquid through the sample paths 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 testing system that can be used with the cartridge assembly of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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 illustrative and is one of the best modes considered for carrying out the present invention. As will be recognized, the present invention is capable of other different and obvious aspects, all without departing from the present invention. Thus, 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 considered in isolation with respect to each other. 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 in order to provide accurate results. The implementations disclosed herein and variations thereof provide 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 the biological test. 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 being introduced 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 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 lengths, paths, 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. The 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 characteristics of the sample fluid. This may include, for example, the sample fluid passing through the sensing elements (20), or the sensing elements (20) protruding into the sample path (18). The determination of the sample fluid characteristics may be performed in a variety of ways, and in the case of an ISE, may include measuring a voltage or other characteristic generated as a result of the sample fluid contacting an operative portion of the sensing elements (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), and the generated voltage 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 on a 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 a transducer assembly (e.g., transducer assembly (122) as shown in FIGS. 6A and 6B) removed. The complete ISE assembly (100) may be used with a biological test system (10) as a sensing element (20). The ISE assembly (100) may be installed within the biological test system (10) such that a 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) may include features to aid in placement, such as a set of mounting tabs (108), that may 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 positioning.

[0034] The sample input (104) is positioned on the housing (102) such that when the ISE assembly (100) is coupled to the biological test system (10), the sample input (104) is aligned with a source of sample fluid (e.g., sample source (14) etc.). 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 more 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 diagram of FIG. 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 exiting at the sample output (112).

[0037] Figures 4 and 5 each show an alternative view of the ISE assembly (100). In Figure 4, the ISE assembly (100) is again shown with the transducer assembly (122) removed, and the transducer receiving portion (114) area can be seen to include the transducer seal (118) and the test portion (116). Figure 4 shows additional detail of the housing (102), including a contoured portion (103), which may be shaped and adapted to aid in positioning the ISE assembly (100) within the biological test system (10).

[0038] 6A and 6B each show a perspective view of the transducer assembly (122). The transducer assembly (122) includes a transducer (126), a threaded portion (128), a mounting nut (130), and a probe (124). The probe (124) terminates in a connector (132) that is conductively coupled to the transducer (126) within the threaded portion (128). When the transducer (126) contacts the fluid sample, a voltage is generated and transmitted through the probe (124) to the connector (132), which is itself adapted to couple to the processor (12) when the ISE assembly (100) is installed in the 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 may 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) is cast directly onto a surface of the body (127).

[0040] The composition and structure of membrane (129) can be varied to produce transducers capable of measuring various substances, as would be apparent to one of ordinary skill 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 aids in sealing 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 feature of the membrane (129). In that view, the transducer assembly (122) can be seen within the transducer assembly socket (106). Although 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, and the like.

[0042] Beneath the threaded portion (128), the transducer (126) can be seen to be positioned within the transducer receiving portion (114) such that the transducer seal (118) contacts the membrane (129) of the transducer (126). The ISE assembly (100) can be assembled in the manner shown, for example, by placing the transducer (126) within the transducer receiving portion (114) and then threading the threaded portion (128) into the transducer assembly socket (106) by turning a mounting nut (130). As the threaded portion (128) is advanced, it contacts the back surface of the transducer (126) and presses the back surface of the transducer (126) against the transducer seal (118). As the membrane (129) is pressed against the transducer seal (118), it will flex and create a pressure seal with the sample passage (120). The threaded portion (128) and mounting nut (130) may be adapted (e.g., by varying their size or location) to control the depth to which the threaded portion (128) may be advanced to allow a suitable pressure to form a seal, but prevent over-tightening that may damage the membrane (129). In addition to such structural limitations, other pressure limiting features may also be implemented (such as by including a torque-activated slip feature in the mounting nut (130), providing a rigid structural contact between the transducer seal (118) and a portion of the transducer (126), or other features) as would be apparent to one of ordinary skill 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 to be exposed to the testing portion (116) in the sample path (120). As the sample fluid flows through the sample path (120), it will contact the membrane (129) and allow 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. In addition, 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 the ISE assembly (100). The pressure seal provided by the 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 the 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 of a similar material. Such materials may be selected to aid in achieving a seal between the components, preventing overtightening of the transducer (126), avoiding conductivity from the transducer (126), or maintaining a seal between the components under various storage conditions during an extended shelf life (e.g., variable temperatures may cause material expansion and contraction for some materials), and such selections will be apparent to one of ordinary skill in the art in light of this disclosure.

[0045] As an additional benefit, the transducer (126) may 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) may be fully assembled without adhesives or other steps, human contact with the membrane (129) may be minimized or avoided entirely. Because contact with the membrane (129) may 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 may reduce errors and improve the accuracy of the test results. As an additional benefit, such an implementation provides a solid transducer (126) and membrane (129), which may provide advantages in 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, and the need to fully inspect the sample path is reduced compared to an ISE that uses a membrane-coated sample path.

[0046] The variable implementation of the ISE assembly (100) may provide a variable contact surface area between the membrane (129) and the sample path (120). For example, some implementations 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 with such contact surface areas are possible due to factors such as the solid design of the transducer (126), the location 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 may also be reduced to less than one second and may 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) may 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) may test a single substance, such that the sample path (18) of FIG. 1 may pass through multiple ISE assemblies (100), with each ISE assembly (100) configured to provide a different measurement. The sample path (18) may pass through the ISE assemblies (100) sequentially, or may 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 in that the sensing element of the reference electrode (200) does not directly contact 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 a distal end that 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 passage (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 to the 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). 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 ion concentrations in a 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 measurement of several specific ion concentrations, such as sodium, potassium, and chloride. Some implementations of such a system may include three ISE assemblies (100), each with a dedicated measurement configuration, along with a reference electrode (200) positioned in sequence along the sample path (18).

[0054] In some implementations of the biological test system (10), the sensing element (20) is located within the sample pathway (18) and may be implemented as a single assembly that includes 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 in a manner similar to that 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 pathway contacts the sensing element along the sample pathway, and then exits the parallel test assembly (300).

[0055] However, in using a parallel test assembly (300), multiple sensing capabilities can be provided and sample fluid measurements can be performed in parallel, and within substantially the same time frame, rather than flowing sequentially 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 FIG. 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) may be tested in parallel, rather than sequentially, by the reference electrode (304), the first electrode (306), the second electrode (308), and the third electrode (310). Thus, in an implementation of the biological test system (10) that tests the concentration of three substances (e.g., sodium, potassium, chloride) in a sample fluid, the parallel test assembly (300) may be used in place of four separate assemblies, and may also advantageously increase sample fluid throughput and speed of testing by performing measurements in parallel.

[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 pulled out of the cap (320) and from within the reservoir (318) in the housing (302). As explained in the context of the reference electrode (200), the reservoir (318) can 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 placed within the reservoir (318) in close 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 into the housing (302) by advancing the threaded portion (324) into the first electrode socket (338). As with 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 as 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 as the corresponding component of the first electrode (306).

[0059] When arranged as shown, the parallel test assembly (300) may be configured such that each electrode provides a different measurement of the sample fluid. By way of example, the first electrode (304) may be configured to measure the sodium content in the sample fluid (e.g., based on the properties of the membrane of the transducer (326)), the second electrode (308) may be configured to measure the potassium content in the sample fluid, and the third electrode (310) may be configured to measure the chloride content in the sample fluid. By using a 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 placement of the electrodes 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 parts omitted for visibility. In that view, the threaded portion (324) of the first electrode (306) can be seen as advanced into the first electrode socket (338), the threaded portion (332) of the second electrode (308) can be seen as advanced into the second electrode socket (340), and the threaded portion (328) of the third electrode (310) can be seen as advanced into the third electrode socket (342). Similarly, the threaded portion (314) of the reference electrode (304) can be seen as advanced into the reference socket (336). With 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 that is not visible in Figure 13 is that of the channels that route the sample fluid to each of the transducers so that the fluid may 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 testing assembly (300) along line BB of 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 can be seen as the sample input (312) passing through the housing (302) and exiting via the sample output (344) leading to a set of channels that define the sample path (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) as similarly 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] In addition, to illustrate the sample path (346) defined by the structure of the housing (302), FIG. 15 shows a flow diagram illustrating the flow of liquid through the parallel test assembly (300). The flow of liquid begins at the sample input (312) and proceeds in the direction indicated by the arrows. Upon reaching the sample divider (354), the flow of liquid splits into four separate channels, each a partial sample input (348), which are similarly received by the respective test portions, 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 right along the partial sample input (348) into the testing portion (350a) and then flow through the testing portion (350a) into the partial sample output (352). Fluid from the partial sample output (352) is then received at the sample junction (356) where the branched sample flows are recombined and then exit via the sample output (344). Similarly, a portion of the fluid proceeds upward from the sample junction (354) into the testing portion (350d) and then flows downward through the testing portion (350d) towards the sample junction (356) where it is recombined with the other sample fluid and exits via the sample output (344). As will be apparent, a portion of the fluid also travels left from sample splitter (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 splitter (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. Splitting and merging of sample fluids can be accomplished by pressurization of the sample fluid input, or both, using the shapes and contours of the structures defining sample path (346), as will be apparent to one of ordinary skill 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), in which an electrode is located. For example, test portion (350c) corresponds to the first electrode (306) and contacts transducer (326), test portion (350a) corresponds to the second electrode (308) and contacts transducer (334), test portion (350b) corresponds to the third electrode (310) and contacts transducer (330), and test portion (350d) corresponds to the 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 such that electrical crosstalk is prevented.

[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 the 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 may travel through the sample path (346) is approximately one-quarter of the longest distance the sample fluid may 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) provides additional advantages in terms of usability and maintenance, as a single assembly may be easier to install and replace than multiple assemblies. Other features, advantages, and modifications of the parallel testing assembly (300) exist and will be apparent to those of ordinary skill in the art in light of this disclosure.

[0066] IV. EXEMPLARY CARTRIDGE ASSEMBLY

[0067] As discussed, the biological test system (10) provides a sample path (18) through which a sample fluid flows and contacts one or more sensing elements (20). Such a system can be advantageously used with assemblies such as the ISE assembly (100), reference electrode (200), and parallel assembly (300), although other types of biological test systems can be implemented in accordance with 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 as to be usable as a portable cartridge-type assembly that can be inserted into and removed from a biological test system (22), such as that shown in Figure 19. Biological test system (22) includes a processor (12) and also includes a 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 outputs (e.g., data indicative of a voltage, electrical signal, or other information), and provide the test outputs to processor (12) for processing and interpretation, as described in the context of Figure 1. The size and shape of cartridge assembly (400) may be varied based on the characteristics of cartridge receiving portion (24), based on utility 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 of skill in the art in light of this disclosure.

[0069] The cartridge (400) includes a sample well (410) as a shallow recess recessed into the body (402). The sample well (410) includes a reference transducer (404), a first transducer (406), a second transducer (408), and a third transducer (412). Each transducer in the sample well (410) functions similarly to the transducers (126) of the ISE assembly (100) in that they generate a voltage in response to contacting a sample fluid, the voltage being 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 membrane of the transducer, 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., either by the effects of surface tension, by 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 the body (402), as can be seen in FIG. 17, in which a first connector (414), a second connector (420), and a third connector (422) can be seen extending from the underside of the body (402) below the sample well (410). Each of the connectors is positioned to conductively couple to a corresponding transducer when inserted and to conductively couple with the cartridge receiver (24) and the processor (12). A reservoir (418) can also be seen with a reference connector (416) extending therefrom in an arrangement similar to reservoir (206) and probe (216) (e.g., the reference connector (416) extends into the reservoir (418), which can be filled with a conductive fluid, with a proximal tip positioned adjacent to but not in contact with the 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] FIG. 18 is a schematic diagram showing an example of such an arrangement. In that view, which simulates a cross-section along line CC of FIG. 18, the sample well (410) can be seen to extend 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) when the cartridge assembly (400) is inserted, extend outwardly from the body (402), and mate with the cartridge receiver (24). 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 lower surface 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) includes four transducers, which may support a configuration including a reference measurement transducer, a sodium concentration transducer, a potassium concentration transducer, and a chloride concentration transducer. Cartridge assembly (400), however, lacks a sample path or fluid flowing through the assembly, instead receiving fluid within sample well (410). Implementations lacking a sample path may be advantageous by reducing the need to pressurize or move sample fluids, reducing the need to clean and wash sample path channels, and preventing carryover contamination between samples (e.g., when cartridge assembly (400) is discarded or cleaned after use).

[0074] Advantages of the cartridge assembly (400) include that it is suitable for use in a clinical setting, and that it can be subsequently discarded or cleaned and reused. As an example, a physician providing treatment directly to a patient may prepare the cartridge assembly (400) by removing it from its packaging, removing the sticker or seal, and exposing the sample well (410). A patient biological sample (e.g., a drop of blood, etc.) may be collected and dripped directly into the sample well (410), or may be collected and prepared separately (e.g., by adding or mixing with reagents, solvents, and other substances) and dripped directly into the sample well (410). The cartridge assembly (400) may then be prepared for transfer by sealing the sample well (410) to prevent the sample from spilling or becoming contaminated during transfer. Cartridge assembly (400) may 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 located remotely to provide services to several healthcare providers. Cartridge assembly (400) may be inserted into cartridge receiving portion (24), and the results may 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.). Once testing is complete, cartridge receiving portion (24) may automatically discard cartridge assembly (400) to prepare cartridge receiving portion (24) for a subsequent cartridge, or it may be manually removed and discarded.

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

[0076] V. EXEMPLARY 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 of this application. No disclaimer is intended. The following examples are provided merely 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 mentioned in the examples below. Thus, none of the aspects or features mentioned below should be considered essential at a later date by the inventor or by the inventor's successors unless otherwise expressly indicated as such. If any claim including additional features beyond those mentioned below is presented in this application or in a subsequent application related to this application, those additional features shall not be considered 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 from 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 receiver such that a liquid solution passing through the sample path contacts the membrane, and (ii) the membrane is configured to generate an electrical potential based on contacting 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 contacts being usable to measure an electrical potential from outside the housing.

[0080] Example 2

[0081] The ion selective electrode of Example 1, wherein the electrical contacts include an internal contact and an external contact, (i) the socket plug is configured to place the internal contact against the membrane structure when mated with the electrode socket, (ii) the external contact extends from the electrical contact to an exterior of the housing, and (ii) the internal contact is mated with the external contact and configured to transfer an electrical potential from the membrane structure to the external contact.

[0082] Example 3

[0083] The ion selective electrode of any one or more of Examples 1-2, wherein the socket plug has threads configured to couple the socket plug and the electrode socket when the socket plug is advanced into the electrode socket and to bias the membrane against the sensing aperture.

[0084] Example 4

[0085] 4. The ion selective electrode of Example 3, wherein the socket plug is configured such that when screwed 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 impermeable 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] The ion-selective electrode described in Example 7, where the solid ion-selective membrane is cast directly onto the 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 against 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 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.

[0104] Example 14

[0105] A method of assembling an ion selective electrode, the method comprising: (a) manufacturing a housing having dimensions selected to suit a desired application, the housing comprising: (i) a sample pathway passing through the housing, the sample pathway 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 from the opening; and (iii) a transducer positioned within the receiver cavity and connected to the sample pathway through the sensing aperture; and (b) creating a membrane structure having dimensions selected to fit within the transducer receiver cavity. , producing a sensor by casting a membrane directly onto a membrane structure, (i) the membrane structure 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 configured to generate an electric potential based on contact with the liquid solution; (c) placing the sensor in 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.

[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, the membrane comprises a solid ion-selective membrane, and further comprising preventing any direct physical contact with the membrane after generation of the sensor 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-impermeable seal between the socket plug and the electrode socket, and (b) a liquid-impermeable seal between the membrane and the sensing opening.

[0112] (Example 18)

[0113] 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 housing having (a) 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 having 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 electrical 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 potential being configured to transmit an electrical 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] A reference electrode as described in Example 20, wherein the socket plug is configured such that when screwed into the electrode socket, it makes contact with the membrane structure, causing the membrane to be compressed against the sensing aperture and forming a liquid-impermeable seal between the membrane and the sensing aperture.

[0120] Example 22

[0121] 1. A parallel testing assembly, comprising: (a) a housing comprising: (i) a sample pathway passing through the housing, the sample pathway comprising a fluid divider on an input side and a fluid junction on an output side, the fluid divider adapted to split fluid into two or more pathways, the fluid junction 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 from the openings connected to the two or more pathways; and (iii) two or more a housing having a reservoir within the housing 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 pathway of the two or more pathways; (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 in the two or more electrode sockets, each of the ion selective electrodes sealing the transducer to the two or more pathways.

[0122] (Example 23)

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

[0124] Example 24

[0125] 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 testing assembly of any one or more of Examples 22-24, wherein (i) a reference electrode is threaded into the reference electrode socket and seals 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 and seals its respective membrane to a respective pathway of the two or more pathways.

[0128] (Example 26)

[0129] A cartridge assembly comprising: (a) a housing adapted to fit within a cartridge-receiving portion of a biological test system; (b) a sample well defined by a recess in a 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 upon contact with a 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 within the sample well. and (f) a set of connectors on a bottom surface of the housing, where (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 proximate 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, the set of connectors being configured to transmit the reference potential and the potentials of the one or more transducers to a processor of the biological testing system when the cartridge assembly is placed into the cartridge receiving portion.

[0130] Example 27

[0131] 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 a 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 with respect to each other. 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 considered to be incorporated by reference herein is incorporated herein, in whole or in part, only to the extent that the incorporated material does not contradict existing definitions, language, or other disclosure material described in this disclosure. Thus, to the extent necessary, the disclosure as expressly set forth herein will supersede any conflicting material incorporated herein by reference. Any material, or portions thereof, that is considered to be incorporated by reference herein but that contradicts existing definitions, language, or other disclosure material described herein will be incorporated only to the extent that it does not create any conflict between the incorporated material and the existing disclosure material.

[0142] Although 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, and 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 terms 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. A 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; and (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 a 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; 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 an electrical potential based on contact with the sample fluid in the sample well; (f) a set of connectors on a bottom surface of the housing; and 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 are 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 within the cartridge receiving portion.

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

3. A cartridge assembly as described in claim 1, wherein the sample well is adapted to hold the sample fluid due to the effect of surface tension.

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

5. A cartridge assembly as described in claim 1, 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.

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