Reference electrode

Abstract

The invention relates to a reference electrode. Systems and methods for a reference electrode are disclosed. In one aspect, a measurement system includes: a dummy reference electrode configured to provide a reference potential; and a dependent electrode configured to generate a dependent potential when exposed to a sample. Both the reference potential and the dependent potential vary based on a property of the sample. The electrochemical sensor includes a dummy reference electrode and a dependent electrode.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] Any and all applications for which foreign or domestic priority claims are identified in the Application Data Sheet filed with the present application are incorporated herein by reference pursuant to 37 CFR 1.57.

[0003] This application claims priority to U.S. Provisional Application No. 63 / 508,993, filed on June 19, 2023, the entire disclosure of which is incorporated herein by reference in its entirety and for all purposes. Technical Field

[0004] The present disclosure relates generally to electrochemical sensors and, more particularly, to reference electrodes for electrochemical sensors. Background Art

[0005] Electrochemical sensors are a class of chemical sensors in which electrodes are used as transducer elements in the presence of an analyte. Electrochemical sensors can convert information related to an electrochemical reaction (e.g., a reaction between an electrode and an analyte) into a useful qualitative or quantitative signal. Electrochemical sensors can produce an electronic output of a digital signal for further analysis. Reference electrodes are used in measurement systems, such as electrochemical sensors, to measure parameters of a solution. The accuracy of the measurement system can depend in part on the consistency and stability of the reference electrode potential. Summary of the invention

[0006] The methods and apparatus of the described technology each have several aspects, no single one of which is solely responsible for its desirable attributes.

[0007] In one aspect, a measurement system is provided, comprising: a pseudo-reference electrode configured to provide a reference potential; and a dependent electrode configured to generate a dependent potential when exposed to a sample, wherein both the reference potential and the dependent potential vary based on properties of the sample, and wherein an electrochemical sensor comprises the pseudo-reference electrode and the dependent electrode.

[0008] In some embodiments, the measurement system further comprises a processing circuit configured to compensate for a dependency in the reference potential based on the dependency potential.

[0009] In some embodiments, the processing circuit is further configured to control a bias potential between the working electrode and the pseudo-reference electrode.

[0010] In some embodiments, the measurement system also includes a counter electrode; and at least one working electrode, wherein the measurement system is configured to measure a parameter of the sample based on at least one of (i) a measured potential between the working electrode and the pseudo-reference electrode, (ii) a current measurement between the working electrode and the counter electrode, (iii) a charge measurement between the working electrode and the counter electrode, or (iv) an impedance measurement between the working electrode and the counter electrode.

[0011] In some embodiments, the at least one working electrode comprises a plurality of working electrodes, and wherein the plurality of working electrodes, the counter electrode, the pseudo-reference electrode, and the dependent electrode are arranged in a column.

[0012] In some embodiments, the pseudo-reference electrode has chloride ion dependence, and wherein the dependent electrode is sensitive to chloride ions.

[0013] In some embodiments, the pseudo-reference electrode is dependent on one or more of: chloride ions, bromide ions, iodide ions, bicarbonate ions, acetate ions, lactate ions, sulfate ions, nitrate ions, potassium ions, sodium ions, temperature, or pH.

[0014] In some embodiments, the pseudo reference electrode includes one or more of Ag, Au, AgCl, Pt, C and / or AgBr.

[0015] In some embodiments, the measurement system further includes a film formed on the pseudo reference electrode.

[0016] In some embodiments, the membrane is a chloride diffusion limiting membrane, wherein the dependent sensor is a chloride electrode, and wherein the property is chloride concentration.

[0017] In some embodiments, the measurement system further comprises a membrane formed on the dependent electrode.

[0018] In some embodiments, the pseudo-reference electrode is stored in a calibration solution.

[0019] In some embodiments, the dependent electrode is stored in the calibration solution.

[0020] In some embodiments, the measurement system further comprises a second dependent electrode configured to generate a second dependent potential when exposed to the sample, wherein both the reference potential and the second dependent potential vary based on a second property of the sample.

[0021] In another aspect, a measurement method is provided, comprising: obtaining a measurement value from a dependent electrode exposed to a sample; and compensating for dependence of a reference potential generated by a pseudo-reference electrode based on the measurement, wherein an electrochemical sensor includes the dependent electrode and the pseudo-reference electrode.

[0022] In some embodiments, the method further comprises generating a measurement of a property of the sample based at least in part on a compensated reference potential generated by the compensating.

[0023] In some embodiments, the method further includes measuring a parameter of the sample based on at least one of (i) a measured potential between the working electrode and the pseudo-reference electrode, (ii) a current measurement between the working electrode and the counter electrode, (iii) a charge measurement between the working electrode and the counter electrode, or (iv) an impedance measurement between the working electrode and the counter electrode.

[0024] In some embodiments, the method further includes obtaining a second measurement from a second dependent electrode exposed to the sample; and compensating for a second dependency of the reference potential generated by the pseudo-reference electrode based on the second measurement.

[0025] In yet another aspect, a measurement system is provided, comprising: a component for providing a reference potential; and a component for generating a dependent potential when exposed to a sample, wherein both the reference potential and the dependent potential vary based on properties of the sample, and wherein the electrochemical sensor comprises a component for providing the reference potential and a component for generating the dependent potential.

[0026] In some embodiments, the measurement system further comprises means for compensating for a dependency in the reference potential based on the dependency potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 An exemplary online measurement system having a plurality of electrodes configured to measure a plurality of parameters according to aspects of the present disclosure is shown.

[0028] Figure 2 is a schematic diagram of an embodiment of a measurement system having a pseudo-reference electrode and a dependent electrode according to aspects of the present disclosure.

[0029] Figure 3A Included are graphs illustrating drift compensation and chloride sensor compensation.

[0030] Figure 3B The voltage of the pseudo-reference electrode with and without compensation is shown. DETAILED DESCRIPTION

[0031] The following detailed description of certain embodiments presents various descriptions of specific embodiments. However, the innovations described herein may be embodied in a variety of different ways, for example, as defined and covered by the claims. In this specification, reference is made to the accompanying drawings in which similar reference numerals and / or terms may indicate identical or functionally similar elements. It should be understood that the elements shown in the figures are not necessarily drawn to scale. In addition, it will be understood that certain embodiments may include more elements than shown in the figures and / or a subset of the elements illustrated in the figures. In addition, some embodiments may combine any suitable combination of features from two or more of the accompanying drawings.

[0032] The measurement system may include a working electrode and a counter electrode, which are configured to measure a specific parameter between the working electrode and the counter electrode. Such a measurement system also generally includes a reference electrode, which is configured to provide a constant and stable defined potential or voltage. In particular, the reference electrode can help bias the working electrode so as to provide stability and consistency for the measurement performed between the working electrode and the counter electrode. Therefore, the reference electrode can provide a stable, well-defined reference voltage, with respect to which any changes in the measurement obtained from the working electrode and the counter electrode can be compared. This enables the measurement system to correct any changes in the voltage at the working electrode, which may occur due to factors other than the desired parameter measurement. Therefore, the use of a reference electrode in such a measurement system can improve the accuracy of the measurement performed using the working electrode. The electrochemical sensor may include one or more working electrodes, a reference electrode and / or one or more counter electrodes. The electrochemical sensor can produce a measurement of a solution property, such as the concentration of certain ions in a fluid. In certain embodiments, the electrochemical sensor may include one or more working electrodes and a reference electrode without using any counter electrode. These embodiments may be used for, for example, a potentiometric sensor, in which the sensor response is based on a voltage measurement between a working electrode and a reference electrode.

[0033] Conventional reference electrodes are relatively large and expensive due to the tolerances involved in designing the reference electrodes to ensure the accuracy of the measurements made by the above-mentioned measurement system. However, for many applications, it may be desirable to provide a smaller measurement system and / or to provide multiple working electrodes, which can measure multiple different parameters. Furthermore, in some applications, the cost of commercial reference electrodes or more "bulky" reference electrodes may be prohibitive. Such different parameters can be measured simultaneously. Figure 1 An exemplary online measurement system 100 having a plurality of electrodes configured to measure a plurality of parameters in accordance with aspects of the present disclosure is shown.

[0034] like Figure 1As shown, the online measurement system 100 includes a plurality of electrodes 110 arranged in a row. In some embodiments, the fluid (e.g., solution) being measured can be controlled to flow through the electrodes 110. According to an embodiment, the electrodes 110 of the online measurement system 100 may include at least one reference electrode and a plurality of working electrodes. In some such embodiments, the electrodes 110 of the measurement system 100 may also include at least one counter electrode.

[0035] In realization Figure 1 There are many design challenges in the compact format of the measurement system 100 shown. For example, it may not be practical to include a conventional reference electrode in the electrode 110. In some embodiments, Figure 1 The reference electrode of the electrode 110 of the measurement system 100 can be implemented by a pseudo-reference electrode. As used herein, a pseudo-reference electrode generally refers to a reference electrode having a potential that can be dependent on a known parameter of the system (or two or more parameters of the system in some applications). Various aspects of the present disclosure relate to systems and techniques that can compensate for the dependence of the pseudo-reference electrode to provide a measurement system with desired accuracy. At the same time, the pseudo-reference electrode can be implemented in a compact measurement system 100.

[0036] The reference electrode structure described herein can be used in applications where other pseudo-reference electrodes (e.g., a relatively low-cost silver|silver chloride pseudo-reference electrode, Ag|AgCl)) are not accurate enough for the required measurement. For example, an Ag|AgCl pseudo-reference electrode may have a chloride content dependence that affects the stability of the Ag|AgCl pseudo-reference electrode. The potential of the Ag|AgCl pseudo-reference electrode may be generally stable, but may change when the chloride content of the solution changes. In some cases, the chloride sensitivity value of the Ag|AgCl pseudo-reference electrode may be greater than 50mV / decade Cl-. Some other pseudo-reference electrodes may have similar dependencies, which may affect the stability of the pseudo-reference electrode.

[0037] When a measurement system designed to measure a parameter of a known solution type (e.g. Figure 1 When used in an online measurement system 100 of a method, a pseudo-reference electrode may be selected that has a dependency on a parameter that is unlikely to be present in the solution. However, for a measurement system designed to measure multiple different parameters, such as Figure 1 This may be impractical or impossible for an online measurement system 100. Therefore, it may be desirable to provide a reference electrode structure that can compensate for one or more dependencies in a pseudo-reference electrode so that the pseudo-reference electrode can be used in an online measurement system while also providing sufficient measurement accuracy.

[0038] There are many example applications where the reference electrode architecture described herein would be superior to other architectures. These applications include, for example, biosensing; industrial; water quality. The reference architecture disclosed herein can be implemented in applications where the reference electrode is stored in a calibration solution or maintenance solution. Alternatively or additionally, the reference architecture disclosed herein can be implemented in applications with single or intermittent electrochemical measurements.

[0039] In some applications, the potential of the reference electrode may not change significantly because the test is relatively fast. For example, the reference electrode structure described herein can be used in a fluid (e.g., microfluidic) system where the reference electrode is continuously stored in a specific "storage solution" or "calibrant" and the reference electrode can be exposed to the analyte or sample for a short period of time. These time periods can vary from a few seconds to a few minutes.

[0040] In the case of an Ag|AgCl pseudo-reference electrode, limiting the amount of time that the Ag|AgCl pseudo-reference cell is exposed to a solution can reduce the response of the Ag|AgCl pseudo-reference circuit to chloride ions present in the solution. An example solution that the Ag|AgCl pseudo-reference electrode can be used to measure is blood. When using the Ag|AgCl pseudo-reference electrode to make measurements in blood and / or other solutions, the Ag|AgCl pseudo-reference electrode may not be stable enough. By using a membrane on the Ag|AgCl pseudo-reference electrode to measure one or more parameters of blood, it is beneficial to provide a membrane on the Ag|AgCl pseudo-reference electrode to reduce chloride dependence, thereby improving the accuracy of the measurement. For measuring other solutions, it may be beneficial to provide a membrane to reduce chloride dependence and / or different ion dependence. Such a membrane can reduce biofouling. The membrane can also be used to improve other parameter dependencies of different pseudo-reference electrodes. For example, the membrane used for a particular pseudo-reference electrode can be configured to reduce the diffusion of dependent ions to the pseudo-reference electrode. In the case of an Ag|AgCl pseudo-reference electrode, the membrane can slow the diffusion of chloride, resulting in a slower potential change than a similar bare Ag|AgCl pseudo-reference electrode without a membrane. In the case of a pseudo-reference electrode with a chloride dependency, a chloride sensor for compensation can include a bare Ag|AgCl electrode (e.g., without a membrane). In some other embodiments, the chloride sensor can include a chloride ion selective sensor (ISE). In some applications, the chloride ISE can include an electrode with an ion selective membrane (ISM) for chloride ions. Similar configurations can be used for pseudo-reference electrodes with different dependencies (e.g., a bromide sensor in which the pseudo-reference electrode has a bromide dependency).

[0041] Various aspects of the present disclosure relate to a pseudo-reference electrode having a membrane configured to reduce the dependency of the pseudo-reference electrode. For example, a membrane may be formed on a pseudo-reference electrode (e.g., an Ag|AgCl pseudo-reference electrode) to slow down ion diffusion (e.g., chloride ion diffusion) into the pseudo-reference electrode. Such a pseudo-reference electrode with a membrane may still have some dependency on specific ions, but may have no or negligible dependency on other ions.

[0042] In some embodiments, the pseudo-reference electrode can include a compound such as a mixture of Ag / AgCl and Ag / AgBr to reduce chloride dependence effects. This can be used when the membrane is not used in the short term, or it can be used together with the membrane in the case of long-term use. In some other embodiments, the pseudo-reference electrode can be used together with the membrane for short-term use, wherein the use of the membrane can slow down diffusion and improve the efficiency of short-term measurement. However, aspects of the present disclosure are not limited thereto, and in some embodiments, the pseudo-reference electrode with or without a membrane can be used for any length of time.

[0043] According to aspects of the present disclosure, the measurement system may include a pseudo-reference electrode and a separate dependent measurement electrode. For example, the dependent measurement electrode (also referred to as a "dependent electrode") may include a chloride electrode (e.g., AgCl, an ion selective membrane for chloride, and / or an epoxy-based chloride sensor). The epoxy-based chloride sensor may include an electrode with a well-known and stable chloride sensitivity.

[0044] The relationship (e.g., potential) between the pseudo-reference electrode and the dependent electrode can be well-defined and stable. Therefore, using the measurement from the dependent electrode, the potential of the pseudo-reference electrode can be measured and used to correct the pseudo-reference electrode potential drift in different solutions. In an embodiment using an Ag|AgCl pseudo-reference electrode, a chloride electrode can be used for the dependent electrode. By knowing the chloride electrode potential from the chloride electrode, the theoretical Ag|AgCl pseudo-reference potential can be easily calculated and can be used to correct the theoretical Ag|AgCl pseudo-reference potential drift in different solutions.

[0045] Figure 2 is a schematic diagram of an embodiment of a measurement system 200 having a pseudo reference electrode 202 and a dependent electrode 204 according to aspects of the present disclosure. Figure 2As shown, the measurement system 200 includes a dependent electrode 204 and a pseudo reference electrode 202. In some embodiments, the measurement system 200 may also include one or more other electrodes 206. In some embodiments, the measurement system 200 may include one or more working electrodes 210 and / or one or more counter electrodes 212. Although the pseudo reference electrode 202, the dependent electrode 204, the other electrodes 206, the working electrode 210, and the counter electrode 212 are shown in a specific configuration (e.g., at a specific location within the measurement system 200), the locations of the different electrodes may be changed without departing from aspects of the present disclosure.

[0046] The pseudo-reference electrode 202 may have a dependency on a parameter, so that the potential of the pseudo-reference electrode 202 may not be consistent and / or stable enough. For example, the pseudo-reference electrode 202 may be dependent on one or more of the following: chloride ions, bromide ions, iodide ions, bicarbonate ions, acetate ions, lactate ions, sulfate ions, nitrate ions, potassium ions, sodium ions, temperature, pH, and / or other ions. In order to compensate for the dependency, the dependent electrode 204 can measure a parameter corresponding to the dependency of the pseudo-reference electrode 202. For example, the dependent electrode 204 can be configured to measure the concentration of chloride ions, bromide ions, iodide ions, bicarbonate ions, acetate ions, lactate ions, sulfate ions, nitrate ions, temperature, and / or pH of a solution.

[0047] In some applications, two or more dependent electrodes 204 can compensate for two or more parameters that affect the reference voltage generated by the pseudo-reference electrode 202. For example, the pseudo-reference electrode 202 can generate a reference voltage that depends on chloride ion concentration and temperature, and the first dependent electrode 204 can measure chloride ion concentration, and the second dependent electrode 204 can measure temperature. As another example, the pseudo-reference electrode 202 can generate a reference voltage that depends on chloride ion concentration and pH, and the first dependent electrode 204 can measure chloride ion concentration, and the second dependent electrode 204 can measure pH.

[0048] although Figure 2 A measurement system 200 with a single pseudo-reference electrode 202 is shown, but aspects of the present disclosure are not limited thereto. For example, the measurement system 200 can include a plurality of different pseudo-reference electrodes 202. In some embodiments, at least two of the pseudo-reference electrodes 202 have different dependencies. In certain embodiments, the measurement system 200 can be configured to select one or more of the pseudo-reference electrodes 202 for a particular solution based on a measurement of the stability of the pseudo-reference electrode 202.

[0049] The measurement system 200 may also include a processing circuit 208, which is configured to compensate the reference potential of the pseudo reference electrode 202 based on the potential of the dependent electrode 204. The processing circuit 208 may include any suitable circuit capable of performing such compensation. The processing circuit 208 may process the compensated reference voltage and the voltage from the working electrode 210 to generate a measurement value of the analyte. In some applications, the processing circuit 208 may process the compensated reference voltage and current between the working electrode 210 and the counter electrode 212 to generate a measurement value of the analyte. In some applications, the processing circuit 208 may process the charge measurement or impedance measurement between the working electrode and the pseudo electrode. In some embodiments, the measurement system 200 may not include the counter electrode 212, so the processing circuit 208 may process the compensated reference voltage and the voltage from the working electrode 210. In some other embodiments, the processing circuit 208 may compensate and process one or more other electrical parameters measured from the pseudo reference electrode 202 and the dependent electrode 204. For example, processing circuit 208 may process measurements of current received from working electrode 210 and, optionally, counter electrode 212 .

[0050] In one embodiment, the dependent electrode 204 includes a chloride ion sensor, and the reference voltage of the pseudo reference electrode 202 has chloride ion dependence. The chloride dependence of the pseudo reference electrode 202 can be corrected (e.g., reduced or eliminated) based on one or more measurements made using the chloride ion sensor of the dependent electrode 204.

[0051] In some embodiments, the sensor substrate material may be: polymer-based (eg, flexible technology, molding, etc.), silicon-based or glass-based (eg, semiconductor material), paper-based, etc.

[0052] In some embodiments, the electrodes of the measurement system 200 can be stored in a "storage solution" and dipped into a sample when needed. In some embodiments, the sample can be added (dispensed, etc.) to the electrodes. The electrodes of the measurement 200 are included in an electrochemical sensor. The measurement system 200 can output a measurement indicating the chemical composition of the sample. The measurement can be represented by an electrical signal.

[0053] According to an embodiment, the measurement system 200 may be part of a (micro)fluidic system comprising channels for introducing a “reservoir solution” or a sample of interest or the like into electrodes of the measurement system 200 .

[0054] The pseudo reference electrode 202 can be implemented using any suitable material. For example, the pseudo reference electrode 202 can include Ag, Au, AgCl, Pt, C and / or AgBr. The pseudo reference electrode 202 can also have a membrane formed on top of the pseudo reference electrode 202 to reduce the size of the dependency. The membrane can be based on imidazolium chloride (or other large organic cation salts with chloride), mixed in a plastic matrix (PVC) with an optional plasticizer, etc.

[0055] In some embodiments, the dependent electrode 204 includes AgCl to detect chloride ions. For example, the dependent electrode 204 may include an epoxy Cl-electrode. The dependent electrode 204 may also include a chloride ion selective membrane configured to allow chloride ions to pass therethrough and to prevent or reduce other ions from passing through the chloride ion selective membrane.

[0056] The pseudo reference electrode 202 can be formed by one or more of Ag, Au, AgCl, Pt, C or AgBr. The pseudo reference electrode 202 can further include a film formed on the electrode. In some embodiments, the film can be based on imidazolium chloride (or other large organic cation salts with chloride), mixed with an optional plasticizer in a plastic matrix (PVC), or the like. In a further embodiment, the film can be based on polydimethylsiloxane (PDMS) (e.g., KCl in PDMS). In other embodiments, the film can be based on a conductive polymer. In one example, the pseudo reference electrode can include a mixture of AgCl with AgBr and / or AgI.

[0057] Figure 3A Included are graphs illustrating drift compensation and chloride sensor compensation. Figure 3B The voltage of the pseudo-reference electrode with and without compensation is shown for various interference steps, namely: calcium step (0.25 mM to 1.7 mM), chloride step (110 mM to 180 mM), acetate step (40 mM to 90 mM), carbonate (20 mM to 40 mM), lactate (10 mM to 20 mM), sulfate (1 mM to 2 mM), and lactated Ringer's solution (25 mM to 50 mM). Figure 3B In the present invention, the AgCl-dependent sensor can be arranged on the same chip or substrate as the pseudo-reference electrode (e.g., Figure 1 and Figure 2 Utilizing the reference electrode compensation disclosed herein, a reference voltage with a precision of a few microvolts can be achieved.

[0058] In some embodiments, the dependent electrode 204 may include non-chlorinated anions instead of chloride anions. Non-chlorinated anions may be more stable at the Ag / AgCl interface. Other example anions that can be used for the dependent electrode include: tris (pentafluoroethyl) trifluorophosphate (FAP), bis (trifluoromethanesulfonyl) imide (TFSI) or bis (fluorosulfonyl) imide (FSI), however, aspects of the present disclosure are not limited thereto.

[0059] In certain embodiments, the dependent electrode 204 may also include one or more transduction layers, which may be planar or 3D. The transduction layer may include laser induced graphene, microporous carbon, carbon nanotubes (CNTs), and the like. The transduction layer may also include colloidally imprinted mesoporous (CIM) carbon, which may be effective with fluorosilicone and PVC matrices on large Au electrodes. The transduction layer may further include an imidazolyl ionic liquid used with TFSI anions, which has been tested in animal serum. The transduction layer may also include an N-methyl-2-pyrrolidone (NMP)-based transduction layer with PVdF, which has shown compatibility as a reference electrode in serum. Phosphorus-based ionic liquids may be used with TFSI anions. The above-mentioned anions described as being included in (one or more) transduction layers are merely examples, and aspects of the present disclosure are not limited thereto. Any suitable principles and advantages of one or more transduction layers may be applied to the pseudo-reference electrode.

[0060] In certain embodiments, a reference electrode ion selective membrane can be placed on top of AgCl as a pseudo reference electrode 202. A chloride sensor (e.g., AgCl or a chloride ion selective electrode) can be used as a dependent electrode 204 to compensate for junction potentials due to changes in chloride concentration in the solution being measured. The reference electrode ion selective membrane can have a different composition (with organic chloride salts, etc.), or can be a PDMS membrane with AgCl mixed in the membrane, or other conductive polymers. Further aspects of the present disclosure relate to algorithms or techniques that can be used to compensate for "drift profiles". In some embodiments, the dependent sensor 204 can include AgBr and / or AgI because these materials can be more stable than AgCl.

[0061] In some embodiments, using Ag as the pseudo-reference electrode 202 can provide greater chloride dependence / sensitivity than a similar AgCl pseudo-reference electrode 202. This can enable the measurement system to measure AgCl versus Ag and use AgCl to compensate for changes in the Ag voltage.

[0062] In certain embodiments, Nafion or other proton or cation exchange membranes (e.g., PEDOT / PSS) can be used for the membrane on the AgCl pseudo-reference electrode 202 to reduce anion diffusion. In other embodiments, the membrane can be graphene oxide to minimize ion diffusion. Any suitable alkaline / anion exchange membrane can be implemented in certain embodiments.

[0063] In some embodiments, the pseudo-reference electrode 202 can be designed without chloride to have a minimal Cl- response. However, the pseudo-reference electrode 202 without chloride may have a significant response to flow changes (e.g., dependence on flow changes). One way to address this dependence is to laminate chloride-saturated and chloride-free pseudo-reference layers.

[0064] In one example, a saturated layer can be provided at the conductive electrode surface, and a chloride-free layer can be provided at the liquid interface. In another example, a saturated layer can be provided at the liquid interface, which can reduce the flow response, and a chloride-free layer can be provided at the conductive electrode surface, which can maintain a low chloride response. In yet another example, a saturated layer can be provided at each of the conductive electrode and the liquid interface, with a chloride-free layer between them.

[0065] In some embodiments, the pseudo reference electrode 202 may include a halide composite reference electrode. For example, instead of AgCl, the pseudo reference electrode 202 may include a composite of AgBr and AgI to improve stability and exchange current density. In addition, in these embodiments, the effect of chloride changes in the analyte can be significantly reduced.

[0066] In the above embodiments, the systems, sensors and methods are described in conjunction with specific embodiments. However, it should be understood that the principles and advantages of the embodiments can be applied to any other systems, sensors or methods requiring the reference electrode disclosed herein.

[0067] Unless the context clearly requires otherwise, throughout the specification and claims, the words "comprises," "comprising," "containing," and the like are to be interpreted in an inclusive sense, and not in an exclusive or exhaustive sense; that is, in the sense of "including but not limited to." In addition, the words "herein," "above," "below," and words of similar meaning as used in this application shall refer to the application as a whole and not to any particular part of the application. Where the context permits, words used in the singular or plural in the detailed description may also include the plural or singular, respectively. When referring to a list of two or more items, the word "or" is intended to cover all of the following interpretations of the word: any item in the list, all items in the list, and any combination of items in the list. All numerical values ​​provided herein are intended to include similar values ​​within measurement error.

[0068] Additionally, unless specifically stated otherwise or otherwise understood in the context of use, conditional language used herein, such as "may," "might," "could," "for example," "such as," etc., is generally intended to convey that some embodiments include and other embodiments do not include certain features, elements, and / or states.

[0069] The teaching provided herein can be applied to other systems, not necessarily the above-mentioned systems. The elements and actions of the various embodiments described above can be combined to provide further embodiments. The actions of the methods discussed herein can be performed in any appropriate order. In addition, the actions of the methods discussed herein can be appropriately performed serially or in parallel.

[0070] Although certain embodiments have been described, these embodiments are presented only by way of example and are not intended to limit the scope of the present disclosure. In fact, the novel methods and systems described herein can be embodied in various other forms. In addition, without departing from the spirit of the present disclosure, various omissions, replacements and changes can be made to the form of the methods and systems described herein. For example, although the disclosed embodiments are presented in a given arrangement, alternative embodiments can utilize different components and / or circuit topologies to perform similar functions, and some elements can be deleted, moved, added, subdivided, combined and / or modified. Each of these elements can be appropriately implemented in various different ways. Any appropriate combination of the elements and actions of the various embodiments described above can be combined to provide further embodiments. The attached claims and their equivalents are intended to cover such forms or modifications that fall within the scope and spirit of the present disclosure. Therefore, the scope of the present invention is defined by reference to the claims.

Claims

1. A measurement system comprising: a pseudo-reference electrode configured to provide a reference potential; and A dependent electrode is configured to generate a dependent potential when exposed to a sample, wherein both the reference potential and the dependent potential vary based on a property of the sample, and wherein an electrochemical sensor includes the pseudo-reference electrode and the dependent electrode. 2 . The measurement system of claim 1 , further comprising a processing circuit configured to compensate for a dependency in the reference potential based on the dependency potential. 3 . The measurement system of claim 2 , wherein the processing circuit is further configured to control a bias potential between the working electrode and the pseudo-reference electrode.

4. The measurement system according to claim 1, further comprising: Counter electrode; and at least one working electrode, wherein the measurement system is configured to measure a parameter of the sample based on at least one of (i) a measured potential between the working electrode and the pseudo-reference electrode, (ii) a current measurement between the working electrode and the counter electrode, (iii) a charge measurement between the working electrode and the counter electrode, or (iv) an impedance measurement between the working electrode and the counter electrode.

5. The measurement system according to claim 4, wherein the at least one working electrode comprises a plurality of working electrodes, and wherein the plurality of working electrodes, the counter electrode, the pseudo-reference electrode and the dependent electrode are arranged in a row. 6 . The measurement system of claim 1 , wherein the pseudo reference electrode has chloride ion dependence, and wherein the dependent electrode is sensitive to chloride ions.

7. The measurement system of claim 1, wherein the pseudo-reference electrode is dependent on one or more of: chloride ions, bromide ions, iodide ions, bicarbonate ions, acetate ions, lactate ions, sulfate ions, nitrate ions, potassium ions, sodium ions, temperature, or pH.

8. The measurement system according to claim 1, wherein the pseudo reference electrode comprises one or more of Ag, Au, AgCl, Pt, C and / or AgBr. 9 . The measurement system according to claim 1 , further comprising a film formed on the pseudo reference electrode.

10. The measurement system of claim 9, wherein the membrane is a chloride diffusion limiting membrane, wherein the dependent sensor is a chloride electrode, and wherein the property is chloride concentration.

11. The measurement system according to claim 1, further comprising a film formed on the dependent electrode.

12. The measurement system of claim 1, wherein the pseudo-reference electrode is stored in a calibration solution.

13. The measuring system according to claim 12, wherein the dependent electrode is stored in the calibration solution.

14. The measurement system of claim 1, further comprising a second dependent electrode configured to generate a second dependent potential when exposed to the sample, wherein both the reference potential and the second dependent potential vary based on a second property of the sample.

15. A measurement method comprising: obtaining measurements from dependent electrodes exposed to the sample; and A dependency of a reference potential generated by a pseudo-reference electrode is compensated based on the measured value, wherein the electrochemical sensor comprises the dependent electrode and the pseudo-reference electrode.

16. The measurement method of claim 15, further comprising generating a measurement of a property of the sample based at least in part on a compensated reference potential generated by the compensating.

17. The measuring method according to claim 15, further comprising: A parameter of the sample is measured based on at least one of (i) a measured potential between the working electrode and the pseudo-reference electrode, (ii) a current measurement between the working electrode and the counter electrode, (iii) a charge measurement between the working electrode and the counter electrode, or (iv) an impedance measurement between the working electrode and the counter electrode.

18. The measuring method according to claim 15, further comprising: obtaining a second measurement from a second dependent electrode exposed to the sample; and A second dependency of a reference potential generated by the pseudo-reference electrode is compensated based on the second measurement value.

19. A measurement system comprising: means for providing a reference potential; and means for generating a dependent potential when exposed to a sample, wherein both the reference potential and the dependent potential vary based on a property of the sample, and wherein the electrochemical sensor comprises means for providing a reference potential and means for generating the dependent potential.

20. The measurement system according to claim 19, further comprising: Means for compensating for a dependency in the reference potential based on the dependency potential.

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