Sensing Assembly

Abstract

The present disclosure provides a sensing assembly (100) for sensing an analyte. The sensing assembly includes a plurality of test electrodes (102) configured to provide signals from a plurality of independent measurements in response to the analyte. Alternatively or additionally, the plurality of test electrodes are configured to generate different transient responses in response to a given concentration of the analyte.

Description

[Technical field]

[0001] The present disclosure relates to sensing assemblies for detecting an analyte, such as a biosensor or chemical assay, sensing assemblies for detecting multiple analytes that are distinct from one another, and systems and methods for determining the concentration of an analyte in a sample matrix. [Background technology]

[0002] A variety of biosensor and chemical assay designs are known for detecting analytes, which may include established biomarkers, such as hormones, to aid in patient monitoring and / or diagnosis.

[0003] For example, in a standard enzyme-linked immunosorbent assay (ELISA) used to quantify analytes such as peptides, proteins, antibodies, hormones, etc., a recognition element is immobilized on a suitable support for selectively interacting with, e.g., binding to, the analyte of interest. For example, an antigen is immobilized on a support and then complexed with an antibody that is linked to an enzyme. Summary of the Invention [Problem to be solved by the invention]

[0004] For biosensors and assays such as ELISA, quantitative measurement of an analyte over a wide range of concentrations has proven difficult: typically, there is a trade-off between sensitivity and the range of concentrations that can be detected. [Means for solving the problem]

[0005] The present disclosure provides a sensing assembly for sensing an analyte, the sensing assembly comprising a plurality of test electrodes configured to provide signals from a plurality of independent measurements in response to the analyte, Alternatively or additionally, the plurality of test electrodes are configured to generate different transient responses in response to a given concentration of the analyte.

[0006] In certain embodiments, a sensing assembly is provided that includes a test electrode device. The test electrode device includes a plurality of test electrodes. Each of the test electrodes has an analyte-interacting portion configured to selectively interact with an analyte. A saturation limit is defined for each of the test electrodes at which the analyte-interacting portion is saturated with the analyte. The respective saturation limits vary between the test electrodes. The sensing assembly further includes a set of control electrodes providing a set of control electrode areas, each control electrode area configured to provide a control measurement that is independent of the analyte. Each control electrode area is provided for one of the test electrodes.

[0007] In certain embodiments, a sensing assembly is provided for sensing a plurality of mutually distinct analytes. The sensing assembly comprises a first test electrode arrangement. The first test electrode arrangement comprises a plurality of first test electrodes. Each of the first test electrodes comprises a first analyte interacting portion configured to selectively interact with a first analyte. A first saturation limit at which the first analyte interacting portion is saturated with the first analyte is defined for each of the first test electrodes. The respective first saturation limits vary between the first test electrodes. The sensing assembly further comprises a second test electrode arrangement and a second set of control electrodes. The second test electrode arrangement comprises a plurality of second test electrodes. Each of the second test electrodes comprises a second analyte interacting portion configured to selectively interact with a second analyte different from the first analyte. A second saturation limit at which the second analyte interacting portion is saturated with the second analyte is defined for each of the second test electrodes. The respective second saturation limits vary between the second test electrodes. The sensing assembly further comprises at least one set of control electrodes providing a set of control electrode areas, each control electrode area configured to provide a control measurement that is independent of the analyte. Each control electrode is provided for one of the first test electrodes and / or one of the second test electrodes.

[0008] In certain embodiments, a system for determining a concentration of an analyte in a sample matrix is ​​provided. The system includes a sensing assembly for sensing an analyte. The sensing assembly includes a test electrode arrangement. The test electrode arrangement includes a plurality of test electrodes. Each of the test electrodes has an analyte-interacting moiety configured to selectively interact with an analyte. A saturation limit is defined for each of the test electrodes at which the analyte-interacting moiety is saturated with the analyte. The respective saturation limits vary between the test electrodes. The sensing assembly further includes a set of control electrodes providing a set of control electrode areas, each control electrode area configured to provide a control measurement that is independent of the analyte. Each control electrode area is provided for one of the test electrodes. The system includes a signal processing unit and a concentration determination unit. The signal processing unit is configured to process signals received from the plurality of test electrodes and to process signals received from the set of control electrode areas. The concentration determination unit is configured to determine a concentration of the analyte in the sample matrix based on the signals processed from the plurality of test electrodes and the signals processed from the set of control electrode areas.

[0009] In certain embodiments, a method is provided for determining a concentration of an analyte in a sample matrix. The method includes processing signals received from a plurality of test electrodes. Each of the test electrodes comprises an analyte-interacting moiety configured to selectively interact with an analyte. A saturation limit at which the analyte-interacting moiety is saturated with the analyte is defined for each of the test electrodes, the respective saturation limits varying between the test electrodes. The method includes processing signals received from a set of control electrodes. The set of control electrodes provides a set of control electrode areas, each control electrode area configured to provide a control measurement that is independent of the analyte. Each control electrode area is provided for one of the test electrodes. The method further includes determining a concentration of the analyte in the sample matrix based on the signals processed from the plurality of test electrodes and the signals processed from the set of control electrode areas.

[0010] The invention will now be described in more detail with reference to the accompanying drawings, which are not intended to be limiting. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 provides a schematic plan view of a sensing assembly according to an embodiment. [Diagram 2] FIG. 2 provides a graph of the sensor signal versus time for the sensing assembly shown in FIG. [Diagram 3] FIG. 3 provides a schematic plan view of electrodes of varying area and a schematic of the immobilization of capture species on the electrodes. [Figure 4] FIG. 4 is a schematic illustrating analyte sensing using a sensing assembly according to another embodiment when the analyte concentration in the sample matrix is ​​relatively high. [Diagram 5] FIG. 5 provides a graph of sensor signal versus time for the sensing assembly and sample matrix shown in FIG. [Figure 6] FIG. 6 illustrates a schematic of analyte sensing using the sensing assembly shown in FIG. 4 when the analyte concentration in the sample matrix is ​​relatively low. [Figure 7] FIG. 7 provides a graph of sensor signal versus time for the sensing assembly and sample matrix shown in FIG. [Figure 8] FIG. 8 provides simplified graphs of sensor signal versus time for higher analyte concentrations (left graph) and lower analyte concentrations (right graph). [Figure 9] FIG. 9 provides a schematic plan view of a set of control electrodes according to an embodiment. [Figure 10] FIG. 10 shows a schematic diagram of a test electrode according to an embodiment. [Figure 11] FIG. 11 illustrates a schematic of an exemplary sensing assembly for sensing multiple distinct analytes. [Figure 12] FIG. 12 provides a block diagram of a system according to an embodiment. [Figure 13] FIG. 13 shows a flow chart of a method according to an embodiment. [Figure 14] FIG. 14 provides a diagram of an exemplary test electrode device having test electrode units and subunits. [Figure 15] FIG. 15 provides a schematic plan view of a test electrode unit and subunit according to another embodiment, and a schematic diagram of the immobilization of a capture species on the test electrode subunit. [Figure 16] 1 provides an illustration of a sensing assembly according to a further embodiment; [Figure 17] 1 provides an illustration of a sensing assembly according to a further embodiment; [Figure 18] 1 provides an illustration of a sensing assembly according to a further embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] A variety of analyte sensing techniques are known that utilize analyte binding techniques. A capture species, or ligand, having specificity for a particular analyte can be used to bind the analyte. Such binding can be detected in a variety of ways, such as colorimetric, fluorescent, or electrochemical.

[0013] Quantitative measurement of an analyte over a wide range of concentrations is challenging, and typically there is a trade-off between sensitivity and the range of concentrations that can be detected.

[0014] Certain embodiments of the present disclosure provide a sensing assembly for sensing an analyte. Such a sensing assembly may include a test electrode device having a plurality of test electrodes, each of the test electrodes having an analyte interactive moiety configured to selectively interact with an analyte.

[0015] The multiple test electrodes may be configured to provide signals from multiple independent measurements in response to the analyte. Alternatively or additionally, the multiple test electrodes may be configured to generate different transient responses in response to a given concentration of the analyte.

[0016] For example, rather than relying solely on equilibrium or end point data, multiple signal inputs may be used to determine analyte concentration.

[0017] Without wishing to be bound by any particular theory, in at least some embodiments, such multiple test electrodes may help provide the sensing assembly with a wider dynamic range, i.e., a wider range from the lowest to the highest concentration of analyte that can be reliably detected by the sensing assembly. Alternatively or additionally, in some embodiments, multiple test electrodes may provide multiple measurement signals, e.g., multiple independent measurement signals, to help provide greater accuracy in determining the analyte concentration.

[0018] In certain embodiments of the present disclosure, the respective saturation limits vary between test electrodes. The saturation limit at which the analyte-interacting moiety of each test electrode is saturated with analyte is defined by the analyte concentration in the sample matrix. This may be indicated by the absence of further change in the signal of each test electrode upon contact with an analyte concentration higher than the analyte concentration defining the saturation limit under otherwise identical conditions.

[0019] In some embodiments, the saturation limit may be considered as the capacity of each test electrode to bind to the analyte, or in other words, may be reached when all available sites of the analyte interacting moiety interact with, e.g., bind to, the analyte.

[0020] The term "analyte concentration" or "concentration of an analyte" as used herein may, in certain embodiments, refer to the activity of the analyte. The activity of the analyte may provide a measure of the effective concentration of the analyte in a sample matrix. Activity can, for example, be useful in taking into account analyte-analyte interactions in the sample matrix and may be more relevant at higher analyte concentrations. Nevertheless, the above specified term "concentration" is used herein for convenience.

[0021] A test electrode device including a test electrode with a higher saturation limit may extend the upper concentration limit of the sensing assembly. Additionally, the rate of signal change may also depend on the analyte concentration. A different transient response to a given analyte concentration may be observed from a lower saturation limit test electrode compared to a higher saturation limit test electrode.

[0022] It should be noted that in at least some biosensor / assay configurations, a so-called "hook effect" is observed at analyte concentrations above the saturation limit: the measured or observed concentration may actually start to decrease in such high analyte concentration regimes.

[0023] In some embodiments, including a test electrode with a higher saturation limit in the sensing assembly may aid in transitioning the high analyte concentration regime in which such hook effects are observed to higher analyte concentrations.

[0024] The analyte may be selected from, for example, molecular species, metal ions, viruses, and microorganisms. Particular mention is made of biomarkers such as cytokines or hormones, as they are of relevance in the context of patient monitoring and diagnostic testing. The analyte may be, for example, a hormone selected from eicosanoids, steroids, amino acids, amines, peptides, or proteins.

[0025] In a non-limiting example, the analyte interacting portion is defined by a capture species provided adjacent to the surface of each test electrode, in such an example, the capture species is configured to selectively interact with the analyte.

[0026] To this end, any suitable capture species may be selected according to the analyte intended to be detected by the detection assembly. For example, the capture species may comprise an antibody having specificity for a particular antigen. In such an embodiment, the analyte may take the form of an antigen.

[0027] More generally, in some embodiments, the capture species may include at least one selected from proteins, peptides, carbohydrates, and nucleic acids.

[0028] The protein can be an enzyme, e.g., an enzyme that has specificity for an analyte. In another non-limiting example, the protein is an antibody. In the latter case, the analyte can be an antigen to which the antibody selectively binds.

[0029] The capture species may, for example, include or be defined by an antigen, in which case the analyte may be a species such as an antibody that is selectively bound by the antigen capture species, and the antigen may, for example, be or include a protein, a peptide, a carbohydrate such as a polysaccharide or a sugar chain.

[0030] In one embodiment, the capture species comprises an aptamer. An aptamer may be defined as an oligonucleotide or peptide configured to bind to an analyte. Such aptamers may be configured to interact with, e.g., bind to, various analyte types, such as, for example, small molecules, e.g., amino acids or amines, proteins, metal ions, and microorganisms.

[0031] In some non-limiting examples, the aptamers are functionalized with an electroactive moiety, e.g., a redox-active moiety, such that a conformational change in the aptamer upon selectively interacting with, e.g., binding to, an analyte causes a change in the proximity of the electroactive moiety to the surface of the respective test electrode.

[0032] In particular, in embodiments in which the test electrodes are configured to determine a change in current associated with selective interaction with an analyte, such changes in proximity of the electroactive moieties to the surface of the respective test electrodes can cause or at least contribute to the determined change in current. Thus, aptamers functionalized with such electroactive moieties can assist in the amperometric sensing of analytes.

[0033] The change in proximity that occurs when an aptamer interacts, e.g., binds, with an analyte can result in, for example, the electroactive moiety being closer to the surface of each test electrode than when the aptamer has not interacted with the analyte. In such an embodiment, in response to an interaction between the analyte and the aptamer, electron transfer between the electroactive moiety and each test electrode can be faster, contributing to an increase in current flow in each test electrode.

[0034] In an alternative non-limiting example, a change in proximity resulting from an aptamer interacting, e.g., binding, with an analyte can result in the electroactive moiety moving farther from the surface of each test electrode than when the aptamer has not interacted with the analyte.

[0035] In such examples, the aptamer can be considered to be conformationally configured in the absence of analyte such that the electroactive moiety, e.g., the redox-active moiety, is in close proximity to or in contact with the test electrode surface, thereby providing a baseline signal.

[0036] In such cases, a decrease in current at each test electrode may be observed in response to the interaction between the analyte and the aptamer. Thus, the higher the concentration of analyte, the greater the decrease in current. Specific non-limiting examples of this are described below with reference to Figures 4-8.

[0037] To this end, any suitable electroactive moiety can be included in the aptamer, such as methylene blue.

[0038] In some embodiments, each test electrode surface is functionalized with a capture species, which may be accomplished in any suitable manner, such as by covalently or non-covalently immobilizing the capture species to the surface.

[0039] For example, a thiol-terminated capture species, such as a thiol-terminated aptamer, can be immobilized, eg, grafted, to the surface of a noble metal, eg, gold, electrode.

[0040] In certain embodiments, the parameter relating to the amount of capture species for each of the test electrodes determines the saturation limit of the respective test electrode, thus, for example, providing different amounts of capture species immobilized on each test electrode.

[0041] For example, when the test electrode surface is functionalized with a capture species, the parameters can include the area of ​​the surface that is functionalized with the capture species.

[0042] Such variation in the area of ​​the surface functionalized with the capture species can be accomplished in any suitable manner. In a non-limiting example, the conductive area of ​​the test electrode is varied in the test electrode device. In this manner, the saturation limit of the test electrode varies due to (at least) the variation in the conductive area functionalized with the capture species.

[0043] In such an embodiment, the area of ​​the surface functionalized with the capture species may correspond to the conductive area of ​​each test electrode.

[0044] Test electrodes having different areas can be arranged, for example, in an array, e.g., the test electrodes can be arranged in an array in order of increasing area, such an array can be considered, for example, as an analyte titration platform.

[0045] Any suitable variation in the saturation limit of the test electrodes may be considered, for example, according to the desired dynamic range of the sensing assembly. For example, the test electrodes may be configured to allow analyte concentration sensing over a range scaled with the logarithm of the concentration, for example.

[0046] In a non-limiting example, the functionalization of each of the conductive regions with a capture species can be uniform for each of the test electrodes, which can allow the same protocol for functionalizing the test electrodes, e.g., the same reagent drop size, reagents, washing, etc., to be used for each of the test electrodes of the test electrode device, and thus, it can be different sizes of conductive regions that determine the varying saturation limits of the test electrodes.

[0047] A relatively high analyte concentration may saturate a smaller area test electrode but not a larger area test electrode. The rate of signal change may also be concentration dependent, as discussed above. Thus, the data generated, for example, the signal change from a smaller area to a larger area electrode, and the rate of signal change, may be used to quantify the analyte.

[0048] In an embodiment in which the capture species includes an aptamer, and a proximity change caused by the aptamer interacting with, e.g., binding to, an analyte causes the electroactive portion of the aptamer to move away from the surface of the respective test electrode, a current can be generated at the test electrode when the analyte does not interact with the aptamer.

[0049] The larger the area of ​​the test electrode, the more capture molecules may be immobilized on its surface, leading to a larger starting current of the test electrode in its virgin state where the analyte has not yet interacted with the aptamer.

[0050] In other non-limiting examples, the area of ​​the surface functionalized with the capture species may be within the conductive region of the respective test electrode and therefore may not correspond to the conductive region. In such examples, the analyte interaction portion may terminate at a boundary. The boundary may be identified using a suitable technique, for example, atomic force microscopy. The area of ​​the analyte interaction portion bounded by the thus identified boundary may then be determined.

[0051] Alternatively or in addition to the parameter including the area of ​​the surface functionalized with the capture species, the parameter may include the density of the capture species on the test electrode surface, where a higher density of the capture species on the surface may help provide a higher saturation limit for the respective test electrode.

[0052] Varying the density of the capture species on the test electrode surface can be performed in any suitable manner, such as by varying the concentration of the capture species, e.g., aptamer, solution used to functionalize the surface. A more concentrated solution can provide a higher density, e.g., packing density, of the capture species on the surface of each test electrode.

[0053] In some embodiments, the capture species may be held adjacent to the surface by a membrane that allows the analyte to pass therethrough, such that the analyte may be captured by the capture species disposed between the test electrode surface and the membrane. A non-limiting example of this is described below with reference to FIG. 10.

[0054] In such non-limiting examples where a capture species is disposed between each test electrode surface and such a membrane, the parameters may include the concentration of the capture species in the solution provided between the membrane and the surface, and thus, by varying the concentration of the capture species for each of the test electrodes, the saturation limit of the test electrodes may be varied.

[0055] In some embodiments, the test electrode apparatus comprises a plurality of units, each unit defining one of the test electrodes and comprising a number of test electrode subunits, in such embodiments, the number of test electrode subunits in each unit determines, at least in part, the saturation limit of the respective test electrode.

[0056] It should be noted that test electrode subunit parameters relating to the amount of capture species for each of the test electrode subunits may further contribute to the determination of the saturation limit of the respective test electrode. Thus, the more general description provided above regarding parameters relating to the amount of capture species for each of the test electrodes is applicable to the test electrode subunits. The test electrode subunit parameters may include, for example, at least one of the area of ​​the surface of each test electrode subunit that is functionalized with a capture species and the density of the capture species on the surface of each test electrode subunit.

[0057] At least some of the test electrode subunits, and in some embodiments each of them, may have the same area as one another. This may allow, for example, to use the same reagent drop size, reagents, washes, etc. for each of these test electrode subunits. Nevertheless, the saturation limit may vary (at least) between units due to the different numbers of test electrode subunits included in each unit. Non-limiting examples of such test electrode devices are described below with reference to Figures 14 and 15.

[0058] In some non-limiting examples, each unit, and possibly one or more test electrode subunits within a unit, may be individually addressable, which may help provide increased configurability to the test electrode apparatus.

[0059] More generally, the test electrodes may include or be formed from any conductive material suitable for use in a sensing assembly, such as a noble metal, e.g., gold or platinum, or titanium nitride.

[0060] More generally, an important consideration of at least some of the embodiments of the present disclosure is that multiple sites with different saturation limits, for example by having different regions functionalized with capture species, may allow a wider range of concentrations to be determined.

[0061] In at least some embodiments of the present disclosure, the sensing assembly further comprises a set of control electrodes providing a set of control electrode areas, each control electrode area configured to provide an analyte-independent control measurement, in such embodiments, each control electrode area is provided relative to one of the test electrodes.

[0062] For example, any of the control electrode regions may include an analyte interactive moiety configured to selectively interact with an analyte. In this manner, each of the control electrode regions may enable a control measurement to be made that is independent of the analyte, and in particular, independent of the concentration of the analyte.

[0063] The set of control electrodes may be arranged in any suitable manner, such as in the form of an array. In embodiments in which the test electrodes are also arranged in an array, the test electrode array and the control electrode array may, for example, extend parallel to one another.

[0064] In certain embodiments, the control electrode areas vary relative to one another. Such variation in control electrode areas can assist in a set of control electrodes providing a control for each of the test electrodes.

[0065] More generally, the test electrode device and a set of control electrodes are arranged to receive a sample matrix, e.g., blood, urine, sweat, tears, etc., which may (potentially) contain the analyte.

[0066] In some non-limiting embodiments, the test electrode device and the set of control electrodes are mounted on a common substrate, e.g., a common semiconductor substrate such as a silicon wafer, an example of which is described below with reference to FIG.

[0067] In an alternative embodiment, the test electrode arrangement is mounted on a first substrate, for example a first semiconductor substrate, and a set of control electrodes is mounted on a second substrate, for example a second semiconductor substrate, for example a (second) silicon wafer.

[0068] The test electrode arrangement and a set of control electrodes may, for example, be disposed in a suitable container or fluidics system, such as a microfluidics system, and the sample matrix may be received in the container or fluidics system such that the sample matrix may be contacted with the test electrode arrangement and a set of control electrodes.

[0069] In some embodiments, the control electrode area is configured for non-selective interaction with the sample matrix. In such embodiments, a set of control electrodes can be considered to provide a negative control measurement. Such a negative control measurement can, for example, determine one or more signals associated with non-selective interaction, e.g., non-specific binding, between the sample matrix and the control electrode area.

[0070] In a non-limiting example, the control electrode region is functionalized with a control aptamer configured not to interact with the analyte. For example, such a control aptamer can include an electroactive moiety, e.g., a redox-active moiety.

[0071] For example, the electroactive portion of the control aptamer may be proximate the surface of each control electrode region, and because the control aptamer does not interact with the analyte, a signal, e.g., a current signal, associated with the control electrode region may remain constant, or at least substantially constant, in the presence of the analyte. Thus, each control electrode region in this non-limiting example may be configured to provide a control measurement that is independent of the analyte. The term "substantially constant" in this context takes into account the relatively small signal changes that result from contact of the sample matrix with the control electrode region.

[0072] The behavior, e.g., amperometric behavior, of such control aptamer-functionalized control electrode regions is contrasted with the behavior of aptamer-functionalized test electrodes, e.g., as described above. In examples where the interaction of the analyte with the aptamer causes the electroactive moiety to migrate toward the surface of the respective test electrode, the current may increase in the presence of the analyte. In alternative examples where the interaction of the analyte with the aptamer causes the electroactive moiety to migrate away from the surface of the respective test electrode, the current may decrease in the presence of the analyte. The different amperometric behaviors of the test and control electrode regions are exemplarily described in more detail herein with reference to Figures 4 to 8.

[0073] Note that any suitable electroactive moiety may be included in the control aptamer, such as methylene blue.

[0074] In certain embodiments, the control electrode regions are configured to selectively interact with non-analyte species contained in the sample matrix. In such embodiments, a set of control electrodes may be considered to provide a positive control measurement. Such a positive control measurement may be based on interaction with a common / ubiquitous species, e.g., molecule, in the sample matrix, e.g., hemoglobin when the sample matrix comprises or is blood, or urea when the sample matrix comprises or is urine.

[0075] More generally, variation of the control electrode area may allow ordering of the control electrode areas by increasing size, and variation of the saturation limit may allow further ordering of the test electrodes by increasing the saturation limit.

[0076] Thus, a series of test electrode-control electrode area pairs can be defined according to an ordering and further ordering, such that the smallest control electrode area is paired with the test electrode having the smallest saturation limit, and the largest control electrode area is paired with the test electrode having the largest saturation limit.

[0077] Such a series of test electrode-control electrode region pairs may be arranged in any suitable manner, for example, the series may extend linearly on the surface of a common substrate, such as a common semiconductor substrate.

[0078] In embodiments, for a series of successive test electrode-control electrode area pairs, the incremental change in control electrode area corresponds to a further incremental change in the saturation limit of the test electrode. The change in control electrode area corresponding to the change in the saturation limit of the test electrode may, for example, be the same as or proportional to the change in the saturation limit of the test electrode, thereby supporting meaningful comparisons to be made between the test and control electrode signals for each test electrode-control electrode pair.

[0079] In this way, contributions to the signal resulting from selective interactions of the analyte-interacting portion of the test electrode and the analyte can be properly distinguished from such contributions to the signal that may be associated solely with the sample matrix.

[0080] In an embodiment, each control electrode area corresponds to the area of ​​the surface of one of the test electrodes that is functionalized with a capture species.

[0081] In a non-limiting example where the area of ​​the test electrodes functionalized with the capture species is varied, it can be the same as the control electrode area, e.g., the area functionalized with the capture species of one of the test electrodes.

[0082] In certain non-limiting examples, the sensing assembly includes a series, e.g., a set, of test-control electrode region pairs, where the test electrodes have different regions functionalized with a capture species, e.g., an aptamer, and for each pair, the control electrode region can be, e.g., identical to the region functionalized with the capture species of the test electrode.

[0083] The regions may have diameters ranging from 1 μm to 500 μm, such as, for example, from 10 μm to 100 μm.

[0084] The area may determine the absolute signal generated, which may mean that a single analyte concentration in a sample matrix may generate multiple signal inputs, for example the absolute change in signal from a smaller area test electrode-control electrode area pair to a larger area test electrode-control electrode area pair, and the rate of signal change, which may be deconvoluted to obtain a particular concentration of analyte.

[0085] More generally, the set of control electrodes may include or be formed from any suitable conductive material, such as a noble metal, e.g., gold or platinum, or titanium nitride.

[0086] In some embodiments, the set of control electrodes includes a plurality of portions, e.g., conductive portions, each of which is individually addressable, In such embodiments, the set of control electrode regions can each be defined by addressing one or more of the plurality of portions.

[0087] Thus, for example, addressing / activating one or a particular combination of those portions via a suitable switching device may allow selection of each control electrode region. The control electrode region may be selected according to the saturation limit of one of the test electrodes, as described above.

[0088] The multiple portions may be arranged in any suitable manner, such as in the form of concentric circles, ellipses, or arcuate portions, and / or as multiple intersections, as in the non-limiting examples shown in Figure 9. Such an arrangement may help conserve space, for example, on the substrate on which the set of control electrodes is disposed.

[0089] The analyte sensing assembly may be compatible with any suitable sensing principle, for example, electrochemical sensing. In some embodiments, the analyte sensing assembly comprises an electrochemical cell including a working electrode assembly and a counter electrode. In such embodiments, the working electrode assembly may include a test electrode device.

[0090] The test electrode device may thus be configured to determine a change in electrical current associated with said selective interaction with the analyte. Such amperometric analyte sensing is mentioned in the context of some of the non-limiting examples above.

[0091] The working electrode assembly may also include a set of control electrodes that may be configured to determine a change in electrical current associated with sample matrix contacting the control electrode regions.

[0092] The counter electrode may act as the positive or negative electrode relative to a working electrode assembly, for example a test electrode device and a set of control electrodes.

[0093] In some embodiments, the electrochemical cell further comprises a reference electrode. The reference electrode may constitute the site of a known chemical reaction having a known redox potential. Any suitable reference electrode may be used, such as a saturated calomel, silver / silver chloride, or copper / copper sulfate reference electrode.

[0094] The fixed redox potential of the reference electrode can provide a reference point for the redox potential of the working electrode assembly. The potential generated within the electrochemical cell can be derived from the working electrode assembly and a current can be measured via the potential of the working electrode assembly set relative to the fixed potential of the reference electrode. A signal / signal change resulting from, for example, interaction of the analyte with the analyte-interacting portion of the test electrode and / or interaction of the sample matrix with the control electrode region can be generated in the external circuit of the electrochemical cell from this potential difference.

[0095] In some embodiments, the sensing electrode assembly may comprise a capacitance and / or impedance determining assembly, for example, as an alternative to or in addition to the electrochemical cell described above. Thus, the principles of the present disclosure may be implemented, for example, in the form of a capacitive and / or impedance sensing array.

[0096] Such a capacitance and / or impedance determining assembly may include a further electrode device, and at least some of the test electrodes of the test electrode device may be spaced apart from the further electrode device so as to enable determination of capacitance and / or impedance between at least some of the test electrodes and the further electrode device.

[0097] The further electrode device can take any suitable form. In some non-limiting examples, the further electrode device itself comprises one or more of the test electrodes, such that each of the spatially separated "plates" of the capacitance and / or impedance determining assembly comprises an analyte interacting portion. Examples of this are described below with reference to Figures 16-18. In other non-limiting examples, the further electrode device does not comprise such an analyte interacting portion, and may be defined, for example, by a non-functionalized electrode.

[0098] The capacitance and / or impedance determining assembly may further comprise a set of control electrodes, the set of control electrodes being spaced apart from the further electrode arrangement so as to enable determination of capacitance and / or impedance between the set of control electrodes and the further electrode arrangement.

[0099] In certain embodiments, a system for determining a concentration of an analyte in a sample matrix comprises a sensing assembly according to any of the embodiments and examples described herein, and a signal processing unit configured to process signals received from a plurality of test electrodes and to process signals received from a set of control electrode regions, the system further comprising a concentration determination unit configured to determine a concentration of the analyte in the sample matrix based on the processed signals from the plurality of test electrodes and the processed signals from the set of control electrode regions.

[0100] In at least some embodiments, the concentration determination unit of the system is configured to determine the concentration of the analyte based on one or more differential signals between signals processed from the plurality of test electrodes and signals processed from a set of control electrode regions.

[0101] In certain embodiments, the concentration determining unit may be configured to determine the concentration based on (at least) the absolute amount of change in the signal at the test electrode-control electrode pair and the rate of change of the signal.

[0102] The signal processing unit and the concentration determination unit may be implemented in any suitable manner using software and / or hardware to perform the various functions required. One or both of the units may perform the necessary functions using, for example, one or more microprocessors programmed using software (e.g., microcode). Examples of processor components that may be used in various embodiments of the present disclosure include, but are not limited to, conventional microprocessors, application specific integrated circuits (ASICs), and field programmable gate arrays (FPGAs).

[0103] In various implementations, one or both of the signal processing unit and the concentration determining unit may be associated with one or more non-transitory storage media, such as volatile and non-volatile computer memories, such as RAM, PROM, EPROM, and EEPROM. The non-transitory storage media may be encoded with one or more programs that, when executed on one or more processors and / or controllers, perform the necessary functions. The various storage media may be fixed within the processor or controller, or may be transportable, such that one or more programs stored on the storage media may be loaded into the signal processing unit and / or the concentration determining unit.

[0104] In some non-limiting examples, the system includes a user interface, such as a display, for communicating the analyte concentration determined by the concentration determining unit.

[0105] Alternatively or additionally, the system may include a communication interface device, such as a wireless transmitter, configured to transmit the analyte concentration determined by the concentration determination unit to an external device, such as a personal computer, tablet, smartphone, remote server, etc.

[0106] In certain embodiments, the sensing assembly is configured to sense a plurality of mutually distinct analytes. In such embodiments, the sensing assembly comprises a first test electrode arrangement. The first test electrode arrangement comprises a plurality of first test electrodes. Each of the first test electrodes comprises a first analyte interacting moiety configured to selectively interact with a first analyte. A first saturation limit is defined for each of the first test electrodes, at which the first analyte interacting moiety is saturated with the first analyte. The respective first saturation limits vary between the first test electrodes.

[0107] In such an embodiment, the sensing assembly further comprises a second test electrode arrangement. The second test electrode arrangement comprises a plurality of second test electrodes. Each of the second test electrodes comprises a second analyte interacting portion configured to selectively interact with a second analyte different from the first analyte. A second saturation limit is defined for each of the second test electrodes at which the second analyte interacting portion is saturated with the second analyte. The respective second saturation limits vary between the second test electrodes.

[0108] The sensing assembly further comprises at least one set of control electrodes providing a set of control electrode areas, each control electrode area configured to provide an analyte-independent control measurement, each control electrode area provided for one of the first test electrodes and / or one of the second test electrodes.

[0109] In a non-limiting example, the at least one set of control electrodes comprises a set of first control electrodes and a set of second control electrodes, in such an example, the first set of control electrodes provides a set of first control electrode areas, each first control electrode area provided for one of the first test electrodes, and the second set of control electrodes provides a second set of control electrode areas, each second control electrode area provided for one of the second test electrodes.

[0110] The sensing assembly may be configured to sense a plurality of mutually distinct analytes, such as two, three, four, five, six or more analytes. To this end, the sensing assembly may comprise a second, third, fourth, fifth, sixth or nth test electrode arrangement and a second, third, fourth, fifth, sixth or nth set of control electrodes.

[0111] In a non-limiting example, test electrodes, such as a first test electrode, a second test electrode, and a set of control electrodes, such as a first control electrode, a second control electrode, may be provided on a single substrate, such as, for example, on a single semiconductor substrate. For example, test electrodes, such as a first test electrode, a second test electrode, and a set of control electrodes, such as, a first control electrode, a second control electrode, may be provided on a common slide, chip, or strip. This example is described herein below with reference to FIG. 11.

[0112] In an embodiment, each of the plurality of analytes is independently selected from a molecular species, a metal ion, a virus, and a microorganism.

[0113] In a non-limiting example, one or more of the plurality of analytes is a biomarker, such as a cytokine or hormone, as such may be relevant in the context of patient monitoring and diagnostic testing.

[0114] One or more, eg, each, of the plurality of analytes can be a hormone selected from, eg, an eicosanoid, a steroid, an amino acid, an amine, a peptide, or a protein.

[0115] In non-limiting examples, the analyte, such as the first analyte, the second analyte, can be a hormone, such as two or more of estradiol (E-2), luteinizing hormone (LH), progesterone, and follicle stimulating hormone (FSH).

[0116] Other than being configured to sense different analytes, the first test electrode arrangement and the second test electrode can be as described above in connection with the test electrode arrangement, and similarly, the first and second sets of control electrodes can be as described above in connection with the set of control electrodes.

[0117] 1 provides a schematic plan view of a sensing assembly 100 according to an embodiment. The sensing assembly 100 comprises a plurality, in this case two, of test electrodes 102 and a corresponding number, in this case two, of control electrode regions 104.

[0118] In the non-limiting embodiment shown in FIG. 1, the test electrodes 102 and the control electrode regions 104 are provided on a common substrate 106, for example a silicon substrate 106, formed, for example, using semiconductor lithography techniques.

[0119] 1 includes a series, e.g., a set, of test electrode-control electrode region pairs 108A, 108B, in which the test electrodes 102 have varying regions functionalized with a capture species configured to interact with, e.g., bind to, an analyte. In this case, the capture species comprises an aptamer. For each pair 108A, 108B, in this non-limiting example, the control electrode region 104 is identical to the region of the test electrode 102 functionalized with the capture species.

[0120] As shown in Figure 1, the control electrode regions 104 are numbered 1 and 3, and the test electrodes 102 are numbered 2 and 4. Figure 2 provides a graph of the sensor signal versus time for the sensing assembly 100 shown in Figure 1 when sensing sample matrices having various analyte concentrations.

[0121] In this non-limiting example, the electroactive moiety is contained in a control aptamer (not visible in FIG. 1) that functionalizes the surface of each control electrode region 104. The electroactive moiety, e.g., methylene blue, is disposed proximal to the surface of each control electrode region.

[0122] A sample matrix containing the analyte is introduced at point 110 in Figure 2. As shown, the signal for control electrode regions numbered 1 and 3 does not change substantially upon addition of analyte because the analyte does not interact with, e.g., bind to, any of the control electrode regions 104. Nevertheless, control electrode region numbered 3 has a larger area functionalized with the control aptamer than control electrode region numbered 1, resulting in a larger absolute signal for control electrode region numbered 3.

[0123] 2 provides plots of three sample matrices, each with a different analyte concentration than the other sample matrices. As the concentration of analyte in each sample matrix increases, as indicated by arrow 112, the signal for test electrode number 4 decreases. This is because the aptamers comprise electroactive moieties that are displaced away from the surface of each test electrode 102 by the interaction of the analyte with the aptamer, as previously described. As indicated by plots 114A, 114B, and 114C, the signal changes with increasing analyte concentration in the sample matrix, with more surface aptamers binding to the analyte.

[0124] Also, as the concentration of analyte in the respective sample matrix increases, the signal for the number 2 test electrode decreases, as indicated by arrow 116. The sample matrix for plot 118A is the same as the sample matrix for plot 114A. Similarly, the sample matrices for plots 118B and 118C are the same as the sample matrices for plots 114B and 114C, respectively.

[0125] Plot 118A indicates that the analyte concentration is such that only a portion of the available aptamers bind to the analyte. Plots 118B and 118C indicate that test electrode number 2 is saturated with analyte since the overall signal change is the same even though the sample matrix for plot 118C has a higher analyte concentration.

[0126] From the circled areas 120 and 122 in Figure 2, it is apparent that a different transient response to a given analyte concentration can be observed from the lower saturation limit test electrode number 2 compared to the higher saturation limit test electrode number 4. In particular, with reference to the circled area 122, it appears that while the overall change in signal is the same for plots 118B and 118C, the rate of change of the signal in plot 118B is clearly different from the rate of change of the signal in plot 118C. The rate of change is noticeably faster in plot 118C where the concentration of analyte is higher.

[0127] Thus, a single analyte concentration in a sample matrix can generate multiple signal inputs, i.e., absolute changes in current and different rates of change of current for the test electrode-control electrode area pair 108A, 108B from smaller to larger areas. Such multiple signal inputs can be deconvoluted to obtain a specific concentration of the analyte. This approach can improve the accuracy of the concentration determination compared to concentrations derived from a single signal input.

[0128] More generally, for example, the current signal may be monitored in the time domain to allow for the determination of the rate of signal change.

[0129] The rate of signal change and the absolute value of the signal, and in some embodiments, additional signal inputs, can be used to determine the analyte concentration.

[0130] FIG. 3 provides in the top pane a schematic plan view of the array test electrodes 102A, 102B, 102C. The conductive regions of each of the test electrodes 102A, 102B, 102C are different from the others as shown. This may allow for the use of the same protocol to functionalize each test electrode. In this regard, the bottom pane of FIG. 3 shows the same reagent drop size 124 being used for each of the test electrodes 102A, 102B, 102C in the test electrode device. Similarly, the same reagents, washes, etc. may be used for each of the test electrodes 102A, 102B, 102C. This may provide a convenient way to realize test electrodes 102A, 102B, 102C with varying saturation limits.

[0131] For example, the drop size 124, corresponding to the maximum diameter of each drop on a plane parallel to the surface of the substrate on which the electrode regions are provided, may be, for example, 10 μm to 150 μm, such as 50 μm to 150 μm, such as 100 μm. The electrode regions may have diameters in the range of 1 μm to 100 μm, such as 10 μm to 100 μm.

[0132] The immobilization of the capture species may utilize droplets of the same size, for example 100 μm, but the capture / functionalization area is in this example based on the conductive area of ​​the electrode.

[0133] In embodiments where the control electrode region 104 is surface functionalized, e.g., with a control aptamer, it should be noted that control electrode regions 104 of different sizes can be achieved in a similar manner using the same reagent drop size, reagents, washes, etc.

[0134] 4 illustrates, in accordance with another embodiment, a schematic diagram of analyte sensing using a sensing assembly 100. The sensing assembly 100 includes a plurality of test electrodes 102, in this case four, and a corresponding number of control electrode regions 104, in this case four.

[0135] More generally, it should be noted that any number of test electrodes 102 (and control electrode regions 104), such as two, three, four, five, six, seven, eight, nine, ten, or more, may be contemplated, for example, according to the desired dynamic range for the sensing assembly 100.

[0136] 4 includes a series, e.g., a set, of test electrode-control electrode region pairs 108A, 108B, 108C, 108D, where the test electrode 102 has a variation region functionalized with a capture species configured to interact with, e.g., bind to, an analyte 126. In this case, the capture species comprises an aptamer 128. For each pair 108A, 108B, 108C, 108D in this non-limiting example, the control electrode region 104 is identical to the region functionalized with the capture species of the test electrode 102.

[0137] In this non-limiting example, an electroactive moiety 130 is included in a control aptamer 132 that functionalizes the surface of each control electrode region 104. An electroactive moiety 130, e.g., methylene blue, is disposed proximate to the surface of each control electrode region 104.

[0138] 4, a conformational change caused by the aptamer 128 interacting with, e.g., binding to, the analyte 126 causes the electroactive moiety 134, e.g., methylene blue, contained in the aptamer 128 to migrate farther from the surface of the respective test electrode 102 than when the aptamer 128 does not interact with the analyte 126. A corresponding decrease in current at each test electrode 102 upon interaction of the analyte 126 with the aptamer 128 is observed, as shown in FIG.

[0139] As shown in Figure 4, the control electrode regions 104 are numbered 1, 3, 5, and 7, and the test electrodes 102 are numbered 2, 4, 6, and 8. Figure 5 provides a graph of the sensor signal versus time for the sensing assembly and sample matrix shown in Figure 4, where the concentration of analyte 126 in the sample matrix is ​​relatively high.

[0140] This relatively high concentration of analyte 126 results in saturation of test electrodes numbered 2, 4, and 6 in Figure 4. As shown in Figure 5, in this particular example, the current at each of test electrodes numbered 2, 4, and 6 decreases and approaches approximately zero current. Test electrode number 8 is not saturated because not all of the aptamers 128 on the surface of this test electrode have interacted with analyte 126. Thus, in this case, the current in test electrode number 8 does not decrease to approximately zero current.

[0141] Because the control aptamer 132 does not bind to the analyte 126, there is substantially no change in the current in the control electrode regions 104, yet a relatively small signal associated with interaction with the sample matrix is ​​observed for each of the control electrode regions 104. As shown in Figure 5, and as previously described with respect to Figures 1 and 2, the absolute signal increases as the control electrode area increases, such that the largest absolute signal is observed at control electrode region number 7.

[0142] FIG. 6 illustrates a schematic of analyte sensing using the sensing assembly 100 shown in FIG. 4, but with a relatively low concentration of analyte 126 in the sample matrix. FIG. 7 provides a graph of the sensor signal versus time for the sensing assembly 100 and sample matrix shown in FIG. 6. In this case, fewer of the test electrodes 102 approach approximately zero current compared to the relatively high concentration scenarios of FIGS. 4 and 5. In particular, only the test electrodes numbered 2 and 4 in FIG. 6 saturate such that the current is approximately zero. The test electrodes numbered 6 and 8 are not saturated at this lower analyte 126 concentration, and therefore do not decrease the current to approximately zero current as do the test electrodes numbered 2 and 4.

[0143] FIG. 8 provides simplified graphs of sensor signal versus time for the higher analyte 126 concentration scenario of FIGS. 4 and 5 (left graph), and the lower analyte 126 concentration scenario of FIGS. 6 and 7 (right graph).

[0144] As can be seen from Figure 8, a higher analyte concentration has the effect of accelerating the signal change and increasing the number of test electrodes 102 at which the current drops to about zero current. Conversely, a lower analyte concentration slows the signal change and reduces the number of test electrodes 102 at which the current drops to about zero current.

[0145] In other words, the absolute decrease in current may depend on the analyte concentration and the saturation limit of the test electrode 102, e.g., the number of functionalized regions / immobilized capture species on the test electrode 102. The rate of change of current may also be concentration dependent.

[0146] Thus, these examples point out the absolute change in current within the smaller to larger area test electrode-control electrode area pair 108A, 108B, and the different rates of change of current that allow for the determination of the concentration of the analyte 126, for example, by deconvolution of such multiple signal inputs, as described above.

[0147] Although the set of control electrodes is shown in Figures 1, 4 and 6 as an array, particularly a linear array, of control electrode regions 104, this is not intended to be limiting. Figure 9 provides a schematic plan view of a set of control electrodes according to an alternative embodiment. The set of control electrodes in this case comprises a plurality of portions, e.g., conductive portions 138A, 138B, 138C, each of which is individually addressable. Each of the set of control electrode regions 104 may be defined by addressing one or more of the plurality of portions 138A, 138B, 138C.

[0148] Thus, for example, it may be possible to select each control electrode area by addressing / activating one or a particular combination of those portions via a suitable switching device (not visible in FIG. 9). For example, a maximum control electrode area may be provided by selecting all three portions 138A, 138B, 138C, and a minimum control electrode area may be selected by selecting only the smallest portion 138A. More generally, as previously mentioned, the control electrode area may be selected according to the saturation limit of one of the test electrodes 102.

[0149] 9, the portions 138A, 138B, 138C may be arranged in the form of concentric circles or ellipses 138A, 138B, 138C. In other non-limiting examples, the portions 138A, 138B, 138C may be arranged in other configurations to form an intersecting arrangement of portions 138A, 138B, 138C. Such an arrangement may help, for example, to conserve space on a substrate on which a set of control electrodes is disposed.

[0150] 9 shows three portions 138A, 138B, 138C, this is not intended to be limiting. Any number of portions 138A, 138B, 138C is contemplated, such as two, four, five, six, seven, eight, or more. The number and size of portions 138A, 138B, 138C may be selected according to, for example, the number and saturation limits of functionalized regions of the test electrode 102.

[0151] 10 illustrates a schematic of a test electrode 102 according to an embodiment in which a capture species is held adjacent to a surface of the test electrode 102 by a membrane 140. The membrane 140 allows an analyte to pass therethrough and thereby be captured by the capture species disposed between the surface of the test electrode 102 and the membrane 140.

[0152] In such a non-limiting example, the parameter related to the amount of captured species at each test electrode 102 may include a concentration of the captured species in a solution 142 disposed between the membrane 140 and the surface of the test electrode 102. By varying the concentration of the captured species in the solution 142 for each of the test electrodes 102, the saturation limit of the test electrodes 102 may be varied.

[0153] In certain non-limiting examples, the capture species includes or is defined by glucose oxidase and the analyte is glucose. When glucose, and in this case oxygen, diffuses, e.g., through the membrane 140 and reaches the solution trapped between the membrane 140 and the test electrode 102, the glucose can be oxidized by the glucose oxidase and the oxygen can be reduced to hydrogen peroxide. The hydrogen peroxide can be electrochemically quantified via its reduction to oxygen and hydrogen cations at the surface of the test electrode 102 such that the glucose concentration can correspondingly be determined.

[0154] 11 illustrates a schematic diagram of an exemplary sensing assembly 100 for sensing multiple mutually distinct analytes. As shown in FIG. 11, the sensing assembly 100 includes a first analyte testing portion 152, a second analyte testing portion 154, a third analyte testing portion 156, and a fourth analyte testing portion 158.

[0155] In the non-limiting embodiment shown in Figure 11, the first through fourth analyte testing portions 152-158 are conveniently provided on a common substrate, such as a common slide / chip / strip. In other embodiments, the analyte testing portions 152-158 may be provided on separate substrates.

[0156] The first analyte testing portion 152 comprises a first test electrode device comprising a plurality of first test electrodes 102. Each of the first test electrodes 102 comprises a first analyte interacting portion configured to selectively interact with a first analyte, in this particular case luteinizing hormone (LH). A first saturation limit, at which the first analyte interacting portion is saturated with the first analyte, is defined for each of the first test electrodes 102. The respective first saturation limits vary among the first test electrodes 102.

[0157] The first analyte testing portion 152 further comprises a first set of control electrodes providing a first set of control electrode areas 104, each of the first control electrode areas 104 configured to provide a control measurement that is independent of each of the analytes. Each control electrode area 104 is provided relative to one of the first test electrodes 102.

[0158] The second analyte testing portion 154 comprises a second test electrode device comprising a plurality of second test electrodes 202 having varying saturation limits and configured to selectively interact with a second analyte, in this particular case estradiol (E-2). The second analyte testing portion 154 also comprises a second set of control electrodes providing a second set of control electrode areas 204, each second control electrode area 204 provided relative to one of the second test electrodes 202.

[0159] The third analyte testing portion 156 comprises a third test electrode device having varying saturation limits and comprising a plurality of third test electrodes 302 configured to selectively interact with a third analyte, in this particular case progesterone. The third analyte testing portion 156 also comprises a third set of control electrodes providing a third set of control electrode areas 304, each third control electrode area 304 provided relative to one of the third test electrodes 302.

[0160] The fourth analyte testing section 158 comprises a fourth test electrode arrangement comprising a plurality of fourth test electrodes 402 having varying saturation limits and configured to selectively interact with a fourth analyte, in this particular case, follicle stimulating hormone (FSH). The fourth analyte testing section 158 also comprises a fourth set of control electrodes providing a fourth set of control electrode areas 404, each fourth control electrode area 404 provided relative to one of the fourth test electrodes 402.

[0161] Table 1 provides concentration ranges for the first through fourth analytes that can be detected by the sensing assembly 100 according to the non-limiting example shown in FIG.

[0162] [Table 1]

[0163] The multiple signals generated for each of the first through fourth analytes can be used to determine their concentration, as described above, using, for example, a suitable algorithm that takes into account the absolute amount of signal change at the test electrode-control electrode pair and the rate of signal change.

[0164] Such a sensing assembly 100 may, for example, enable the concentrations of multiple analytes to be measured periodically, e.g., daily. Such concentrations may then be tracked and, in some embodiments, uploaded, and an individual user profile may be generated based on the uploaded concentrations. In this manner, concentrations obtained via the sensing assembly 100 may be used for clinical decisions regarding, for example, dosage and / or timing of administration of the dosage.

[0165] FIG. 12 provides a block diagram of a system 500 according to an embodiment. The system 500 is for determining a concentration of an analyte in a sample matrix. The system 500 comprises a sensing assembly 100 for sensing an analyte. The sensing assembly 100 comprises a test electrode arrangement 502. The test electrode arrangement 502 comprises a plurality of test electrodes 102. Each of the test electrodes 102 has an analyte-interacting portion configured to selectively interact with an analyte. A saturation limit is defined for each of the test electrodes 102, where the analyte-interacting portion is saturated with the analyte. The respective saturation limits vary between the test electrodes 102. The sensing assembly 100 further comprises a set of control electrodes 504 providing a set of control electrode areas 104, each control electrode area 104 being provided for one of the test electrodes 102.

[0166] Thus, the sensing assembly 100 included in the system 500 may follow any of the examples and embodiments described herein.

[0167] The system 500 also includes a signal processing unit 506 and a concentration determination unit 508. The signal processing unit 506 is configured to process signals received from the plurality of test electrodes 102 and to process signals received from the set of control electrode regions 104. The concentration determination unit 508 is configured to determine a concentration of an analyte in the sample matrix based on the processed signals from the plurality of test electrodes 102 and the processed signals from the set of control electrode regions 104.

[0168] In at least some embodiments, the concentration determination unit 508 is configured to determine the concentration based on one or more differential signals from signals processed from the multiple test electrodes 102 and signals processed from a set of control electrode regions 104.

[0169] In a non-limiting example, the concentration determining unit 508 is configured to determine the concentration based on the absolute amount of signal change and the rate of signal change at the test electrode-control electrode pairs 108A, 108B, 108C, 108D.

[0170] 12, a user interface, such as a display, may be included in the system 500 for communicating the analyte concentration determined by the concentration determining unit 508. Alternatively or additionally, the system 500 may include a transmitter (also not visible in FIG. 12), such as a wireless transmitter, configured to transmit the analyte concentration determined by the concentration determining unit 508 to an external device, such as a personal computer, tablet, smartphone, remote server, or the like.

[0171] 13 shows a flow chart of a method 600 according to an embodiment. The method 600 is for determining a concentration of an analyte in a sample matrix. The method includes, at block 602, processing signals received from a plurality of test electrodes. Each of the test electrodes comprises an analyte interacting moiety configured to selectively interact with an analyte. A saturation limit at which the analyte interacting moiety is saturated with the analyte is defined for each of the test electrodes, with the respective saturation limits varying between the test electrodes.

[0172] The method 600 also includes processing signals received from the set of control electrodes at block 604. The set of control electrodes provides a set of control electrode areas, each control electrode area configured to provide an analyte-independent control measurement, each control electrode area provided relative to one of the test electrodes.

[0173] At block 606, the concentration of the analyte in the sample matrix is ​​determined based on signals processed from the multiple test electrodes and signals processed from a set of control electrodes.

[0174] In some embodiments, determining the concentration of the analyte (606) includes determining one or more differential signals from signals processed from the plurality of test electrodes and signals processed from a set of control electrodes.

[0175] In a non-limiting example, the decision 606 is based on the absolute amount of signal change and the rate of signal change at the test electrode-control electrode pair.

[0176] Method 600 may employ, for example, sensing assembly 100 and / or system 500 according to any of the embodiments and examples described herein.

[0177] In particular, the method 600 may be implemented using the signal processing unit 506 and the concentration determining unit 508 of the system 500 of the present disclosure.

[0178] In certain embodiments, a computer program including computer program code is adapted to implement the method 600 according to any of the examples and embodiments described herein when the program is executed on a computer. Such a computer may be included in or define, for example, the signal processing unit 506 and the concentration determination unit 508 of the system 500 of the present disclosure. The computer program may be stored on one or more non-transitory computer readable media. The computer program may include instructions executed by one or more physical computing devices, such as one or more processors, that can cause the one or more processors to implement, execute, and / or perform one or more methods described herein.

[0179] More generally, examples and embodiments described herein with respect to sensing assembly 100 may be applicable to system 500, method 600, and / or computer program. Similarly, examples and embodiments described herein with respect to system 500, method 600, and / or computer program may be applicable to sensing assembly 100.

[0180] 14 provides a diagram of a test electrode apparatus 502 according to a non-limiting example. The depicted test electrode apparatus 502 comprises a plurality of units 702A, 702B, 702C, where each unit 702A, 702B, 702C defines one of the test electrodes and comprises a plurality of test electrode subunits 703. The number of test electrode subunits 703 in each unit 702A, 702B, 702C determines, at least in part, the saturation limit of the respective test electrode.

[0181] When each unit 702B, 702C includes two or more test electrode subunits 703, the test electrode subunits 703 of each unit 702B, 702C may be interconnected, as shown in FIG.

[0182] 14 are provided on a common substrate 106. Nevertheless, it should be noted that in other embodiments, at least some of the units 702A, 702B, 702C may be provided on a different substrate than the other units 702A, 702B, 702C.

[0183] 14, the test electrode subunits 703 are arranged linearly with respect to each unit 702A, 702B, 702C. This spatial arrangement allows the test electrode subunits 703 to be easily functionalized, for example, when a reagent is dispensed simultaneously onto two or more of the test electrode subunits 703. Nevertheless, alternative spatial arrangements of the test electrode subunits 703 are contemplated, for example, to conserve space on the substrate 106.

[0184] 14, unit 702A has a single test electrode subunit 703, unit 702B has two test electrode subunits 703, and unit 702C has four test electrode subunits 703. More generally, any number of test electrode subunits 703 per unit 702A, 702B, 702C may be contemplated to allow for variation in the saturation limits of units 702A, 702B, 702C without necessarily requiring different functionalization protocols / reagents to be used to create each unit 702A, 702B, 702C.

[0185] 14, each test electrode subunit 703 has the same area as each other. This may allow, for example, to use the same reagent drop size, reagents, washes, etc. for each of these test electrode subunits 703.

[0186] 15 illustrates, in schematic form, an exemplary functionalization process in which the same reagent drop size 124 is used for each of the test electrode subunits 703. This may provide a convenient way of achieving units 702A, 702B, 702C with varying saturation limits.

[0187] Droplet size 124, e.g., the maximum diameter of each drop in a plane parallel to the surface of substrate 106, may be, for example, 10 μm to 150 μm, such as 50 μm to 150 μm, such as 100 μm. The area of ​​each of the test electrode subunits 703 may be, for example, in the range of 1 μm to 100 μm, such as 10 μm to 100 μm.

[0188] More generally, at least some of the units 702A, 702B, 702C may have subunits 703 designed to have overlapping analyte-depleted diffusion / mass transport regions such that each unit 702A, 702B, 702C may function as a single larger test electrode with varying transient response.

[0189] Alternatively or additionally, at least some of the units 702A, 702B, 702C may have subunits 703 that are physically spaced apart from one another within the respective units 702A, 702B, 702C so as not to have overlapping analyte-depleted diffusion / mass transport regions. Each such unit 702A, 702B, 702C may act as a larger area electrode having a relatively constant transient response.

[0190] 16-18 generally illustrate diagrams of exemplary sensing assemblies 100, each of which includes a capacitance and / or impedance determining assembly.

[0191] Such a capacitance and / or impedance determining assembly may comprise a further electrode arrangement 802A, and at least some of the test electrodes 802B of the test electrode arrangement may be spaced apart from the further electrode arrangement such that the capacitance and / or impedance between said at least some of the test electrodes 802B and the further electrode arrangement 802A may be determined. The test electrodes have varying saturation limits, as previously described.

[0192] The further electrode arrangement 802A and at least some of the test electrodes 802B may be arranged relative to each other in any suitable manner, such as using a cross-arrangement as shown diagrammatically in FIG.

[0193] 16, a further electrode arrangement 802A may extend from the first contact 803A and at least some of the test electrodes 802B may extend from the second contact 803B. In this non-limiting example, the first and second contacts 803A, 803B and the electrode arrangements 802A, 802B are disposed on a common substrate 106, such as a common semiconductor substrate.

[0194] In a non-limiting example shown in FIG. 16, the further electrode device 802A itself comprises one or more of the test electrodes, such that each of the intersecting "plates" of the spatially separated capacitance and / or impedance determination assembly comprises an analyte-interacting moiety, for example in the form of a surface functionalized with the capture species described above.

[0195] 17, which shows a cross-section of a portion of a capacitance and / or impedance determination assembly, both electrode devices 802A, 802B are elevated above the surface of substrate 106. Thus, an electric field is established above the surface of substrate 106, with electric field lines 805 extending above the gap provided between electrode devices 802A, 802B.

[0196] 18, a trench 807 is provided between the electrode devices 802A, 802B. In this embodiment, the electrode devices 802A, 802B, e.g., interdigitated electrode devices 802A, 802B, may be set within the substrate 106 as shown.

[0197] It should be understood that the detailed description and specific examples, while setting forth exemplary embodiments of the devices, systems, and methods, are for purposes of illustration only and are not intended to be limiting in scope. These and other features, aspects, and advantages of the devices, systems, and methods of the present invention may be better understood from the description, the appended claims, and the accompanying drawings. It should be understood that the drawings are merely schematic and are not drawn to scale. It should also be understood that the same reference numbers are used throughout the figures to denote the same or similar parts.

[0198] Other variations of the embodiments of the present disclosure can be understood and effected by those skilled in the art, from a study of the drawings, the disclosure, and the appended claims, and by practicing the disclosure. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. 1. A sensing assembly for sensing an analyte, the sensing assembly comprising: a test electrode device comprising a plurality of test electrodes, each of the test electrodes comprising an analyte-interacting portion configured to selectively interact with the analyte, a saturation limit at which the analyte-interacting portion is saturated with the analyte defined for each of the test electrodes, the respective saturation limits being different among the test electrodes; a set of control electrodes providing a set of control electrode areas, each control electrode area configured to provide a control measurement that is independent of the analyte, each control electrode area provided relative to one of the test electrodes; Equipped with the test electrode device and the set of control electrodes are positioned to receive a sample matrix suitable for containing the analyte; the sensing assembly comprises an electrochemical cell including a working electrode assembly and a counter electrode, the working electrode assembly comprising the test electrode device, the test electrode device configured to determine a change in current associated with selective interaction with the analyte; A sensing assembly, wherein the working electrode assembly comprises the set of control electrodes, the set of control electrodes configured to determine a change in electrical current associated with the sample matrix contacting the control electrode regions.

2. The sensing assembly of claim 1 , wherein the control electrode areas are different relative to one another.

3. 3. The sensing assembly of claim 2, wherein the differences in the control electrode areas allow the control electrode areas to be ordered by increasing size, and the differences in the saturation limits allow the test electrodes to be further ordered by increasing saturation limits, such that a series of test electrode-control electrode area pairs are defined according to the ordering and further ordering, with the smallest control electrode area paired with the test electrode having the smallest saturation limit and the largest control electrode area paired with the test electrode having the largest saturation limit.

4. 4. The sensing assembly of claim 3, wherein for successive test electrode-control electrode area pairs in the series of test electrode-control electrode area pairs, an incremental change in the control electrode area corresponds to a further incremental change in the saturation limit of the test electrode.

5. 5. The sensing assembly of claim 1, wherein each analyte-interacting portion is defined by a capture species provided adjacent to a surface of a respective test electrode, the capture species being configured to selectively interact with the analyte.

6. The sensing assembly of claim 5 , wherein the capture species comprises at least one selected from a protein, a peptide, a carbohydrate, and a nucleic acid.

7. The detection assembly described in claim 6, wherein the protein is an enzyme.

8. The sensing assembly of any one of claims 5 to 7, wherein the capture species comprises an aptamer.

9. The sensing assembly of any one of claims 5 to 8, wherein the surface is functionalized with the capture species.

10. A sensing assembly according to any one of claims 5 to 8, wherein the capture species is held adjacent to the surface by a membrane.

11. The sensing assembly of any one of claims 5 to 10, wherein a parameter related to the amount of the capture species for each of the test electrodes at least partially determines the saturation limit of the respective test electrode.

12. A sensing assembly as described in claim 9, wherein a parameter related to the amount of the capture species for each of the test electrodes at least partially determines the saturation limit of each of the test electrodes, and the parameter includes at least one of the area of ​​the surface functionalized with the capture species and the density of the capture species on the surface.

13. 13. The sensing assembly of claim 12, wherein each control electrode area corresponds to the area of ​​the surface of one of the test electrodes that is functionalized with the capture species.

14. A sensing assembly as described in claim 10, wherein a parameter related to the amount of the capture species for each of the test electrodes at least partially determines the saturation limit of each of the test electrodes, the parameter including the concentration of the capture species in the solution provided between the membrane and the surface.

15. 15. A sensing assembly according to any preceding claim, wherein each of the set of control electrodes comprises a plurality of individually addressable portions, and each of the set of control electrode regions is defined by addressing one or more of the plurality of portions.

16. 16. The sensing assembly of claim 1, wherein the test electrode device comprises a plurality of units, each unit defining one of the test electrodes and comprising a plurality of test electrode subunits, the number of test electrode subunits in each unit at least partially determining the saturation limit of each of the test electrodes.

17. A sensing assembly according to any preceding claim, wherein the control electrode region is configured for non-selective interaction with the sample matrix.

18. 17. A sensing assembly according to any preceding claim, wherein the control electrode region is configured to selectively interact with non-analytes contained in the sample matrix.

19. The sensing assembly of any preceding claim, wherein the electrochemical cell further comprises a reference electrode.

20. A sensing assembly according to any preceding claim, comprising a capacitance and / or impedance determining assembly comprising the test electrode arrangement.

21. 21. The sensing assembly of claim 20, wherein the capacitance and / or impedance determining assembly comprises a further electrode arrangement, and at least some of the test electrodes of the test electrode arrangement are spaced apart from the further electrode arrangement so as to be able to determine capacitance and / or impedance between at least some of the test electrode arrangements and the further electrode arrangement.

22. 22. The sensing assembly of claim 21, wherein the capacitance and / or impedance determining assembly further comprises the set of control electrodes, the set of control electrodes being spaced apart from the further electrode arrangement so as to be able to determine the capacitance and / or impedance between the set of control electrodes and the further electrode arrangement.

23. 1. A sensing assembly for sensing a plurality of mutually distinct analytes, said sensing assembly comprising: a first test electrode device comprising a plurality of first test electrodes, each of the first test electrodes comprising a first analyte-interacting portion configured to selectively interact with a first analyte, a first saturation limit at which the first analyte-interacting portion becomes saturated with the first analyte is defined for each of the first test electrodes, and each of the first saturation limits differs among the first test electrodes; a second test electrode device comprising a plurality of second test electrodes, each of the second test electrodes comprising a second analyte-interacting portion configured to selectively interact with a second analyte different from the first analyte, a second saturation limit at which the second analyte-interacting portion becomes saturated with the second analyte is defined for each of the second test electrodes, and each second saturation limit varies among the second test electrodes; at least one set of control electrodes providing a set of control electrode areas, each control electrode area configured to provide a control measurement that is independent of the analyte, each control electrode area provided relative to one of the first test electrode and / or the second test electrode; A sensing assembly comprising:

24. 1. A system for determining the concentration of an analyte in a sample matrix, comprising: A sensing assembly according to any one of claims 1 to 23; A signal processing unit, processing signals received from the plurality of test electrodes; and a signal processing unit configured to process signals received from the set of control electrode regions; a concentration determination unit configured to determine the concentration of the analyte in the sample matrix based on the signals processed from the plurality of test electrodes and the signals processed from the set of control electrode regions; A system comprising:

25. 25. The system of claim 24, wherein the concentration determination unit is configured to determine the concentration based on one or more differential signals between the signals processed from the plurality of test electrodes and the signals processed from the set of control electrode regions.

26. 26. The system of claim 24 or 25, wherein the concentration determination unit is configured to determine the concentration based on an absolute amount of change in the processed signals from the test electrode and the set of control electrode regions and a rate of change of the processed signals from the plurality of test electrodes.

27. 1. A method for determining the concentration of an analyte in a sample matrix, comprising: processing signals received from a plurality of test electrodes, each of the test electrodes comprising an analyte-interacting portion configured to selectively interact with the analyte, a saturation limit at which the analyte-interacting portion is saturated with the analyte defined for each of the test electrodes, the respective saturation limits differing among the test electrodes; processing signals received from a set of control electrodes, the set of control electrodes providing a set of control electrode areas, each control electrode area configured to provide a control measurement that is independent of the analyte, each control electrode area provided relative to one of the test electrodes; the test electrode device and the set of control electrodes are positioned to receive the sample matrix; the sensing assembly comprises an electrochemical cell including a working electrode assembly and a counter electrode, the working electrode assembly comprising the test electrode device, the test electrode device configured to determine a change in current associated with selective interaction with the analyte; processing, wherein the working electrode assembly comprises the set of control electrodes, the set of control electrodes configured to determine a change in electrical current associated with the sample matrix contacting the control electrode regions; determining the concentration of the analyte in the sample matrix based on the signals processed from the plurality of test electrodes and the signals processed from the set of control electrode regions; A method comprising:

28. 28. The method of claim 27, wherein determining the concentration of the analyte comprises determining one or more differential signals from the signals processed from the plurality of test electrodes and the signals processed from the set of control electrode regions.

29. 29. The method of claim 27 or 28, wherein determining the concentration of the analyte is based on an absolute change in the processed signal from the test electrode and the set of control electrode regions and a rate of change of the processed signal from the plurality of test electrodes.

30. 30. A computer program comprising computer program code, the computer program being configured, when said computer program is executed on one or more physical computing devices, to cause said one or more physical computing devices to implement a method according to any one of claims 27 to 29.

31. One or more non-transitory computer readable media having a computer program stored thereon, the computer program comprising computer program code configured, when executed on one or more physical computing devices, to cause the one or more physical computing devices to implement the method of any one of claims 27 to 29.

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