Determination of sensor operating status via sensor query

Abstract

The present invention provides a method and system for operating a gas sensor for a gas analyzer that includes detection components. [Solution] A method for operating a gas sensor for a gas analyzer including a detection component includes, as a first mode, querying the sensor by periodically applying an electrical signal to the detection component of the sensor, measuring the sensor response to the electrical signal indicating the sensitivity of the sensor each time the electrical signal is applied to the detection component, determining whether one or more thresholds have been exceeded based on the sensor response determined each time the electrical signal is applied to the detection component, and, if one or more thresholds have been exceeded, entering a second mode different from the first mode in the analysis of the sensor response to the periodically applied electrical signal.

Description

Technical Field

[0001] Cross - reference to Related Applications This application claims the benefit of U.S. Provisional Patent Application No. 62 / 738,190, filed on September 28, 2018, the disclosure of which is incorporated herein by reference.

Background Art

[0002] The following information is provided to assist the reader in understanding the technology disclosed hereinafter and the environments in which such technology may typically be used. The terms used herein are not intended to be limited to a particular narrow interpretation unless otherwise clearly defined in this document. References described herein can facilitate understanding of the technology or its background. The disclosure of all references cited herein is incorporated by reference.

[0003] Gas sensors, such as electrochemical sensors, have been proven effective over the decades in detecting gases such as toxic gases in workplace environments. For example, the low cost, response speed, and selectivity of electrochemical gas sensors are just some of the features that make such sensors attractive for safety - related products. However, one of the necessary requirements for using electrochemical gas sensors and other gas sensors is frequent calibration. For example, the sensitivity of an electrochemical sensor is affected by the moisture content of the electrolyte, which changes as a result of fluctuations in the ambient relative humidity, such as due to season or geographical location. Such fluctuations in relative humidity lead to a decrease in sensitivity in dry regions or dry seasons and an increase in sensitivity in humid regions or humid seasons.

[0004] Therefore, it is indicated that gas detection instruments, including electrochemical gas sensors and / or other gas sensors, should be carefully and periodically tested for functionality. For example, frequent calibration with test gases having analytes or target gases of known concentrations (including non-zero and zero concentrations) is required to adjust for the sensitivity changes described above. For example, it is common to perform routine "bump checks" or functional checks on portable gas detectors. The purpose of this test is to verify the functionality of the entire gas detection system, commonly referred to as an instrument. Periodic bump checks or functional checks may also be performed on permanent gas detectors, for example, to extend the interval between full calibrations. A gas detection system includes at least one gas sensor and electronic circuitry (including a power supply) for driving the sensor, interpreting its response, and displaying the response to the user. The system further includes a housing to enclose and protect such components. Bump checks typically involve a) applying a test gas of interest (usually a known concentration of the target gas or analyte gas that the instrument is intended to detect, or a dummy gas to which the instrument is responding), b) collecting and interpreting sensor responses, and c) indicating the functional status of the system (i.e., whether the instrument is functioning properly) to the end user.

[0005] Traditionally, bump tests were performed regularly, typically daily. Bump checks provide users with a relatively high degree of assurance that the gas detection device is functioning correctly. Bump checks perform all necessary functions of all parts of the gas detection device in a similar manner to that required to detect alarm levels of hazardous gases. In this regard, bump checks ensure efficient gas delivery from outside the device via any transport routes (e.g., including any protective and / or diffusion membranes) to contact the active sensor components. Bump checks also verify that the sensing surface of the sensor itself is functioning correctly and that the sensor provides the appropriate response function or signal. Bump checks further verify that the sensor is properly connected to its associated power supply and electronic circuitry and that the sensor signal is being interpreted correctly. In addition, bump checks verify that one or more indicators of the gas detector, as well as one or more user interfaces (e.g., display and / or notification functions), are functioning as intended.

[0006] However, periodic / daily bump checks have many significant drawbacks. For example, such bump checks are time-consuming, especially in facilities like industrial facilities that include several gas detection systems or instruments. Bump checks also require the use of expensive and potentially hazardous calibration or test gases. Furthermore, bump checks typically require a specialized gas supply system, including pressurized gas bottles, pressure regulators, and tubing and adapters to properly supply the calibration or test gas to the instrument. The need for a specialized gas supply system often means that opportunities to bump check personal gas detection devices are limited to a certain location and time, depending on the availability of the gas supply equipment.

[0007] In recent years, several systems and methods have been proposed to reduce the number of bump tests required. Such systems may include, for example, electronic querying of sensors in the absence of a test gas. Variations in the sensitivity of electrochemical gas sensors resulting from moisture loss or increase in numerous sensors occur gradually but predictably as the mean relative humidity changes slowly. Similarly, the sensor response to electronic querying (when no test gas containing the analyte gas or its substitutes at known concentrations is present or applied) also changes. Electronic querying can be used, for example, to measure and correct for changes in sensitivity. Such electronic querying techniques and the resulting correction of electrochemical gas sensors are disclosed, for example, in U.S. Patents 7,413,645, 7,959,777, 9,784,755, 9,528,957, and U.S. Patent Application Publications 2013 / 0186777 and 2017 / 0219515, which are incorporated herein by reference. In this type of electronic querying approach, an electrical signal, such as a potential pulse, is typically applied to the sensor's sensing element or component, and the resulting response is measured and recorded. The response may be measured, for example, in the form of a maximum peak (current) value (MPV) or / or other parameters. These responses are compared to values ​​obtained during previous gas tests / pulse cycles. Changes from calibration values ​​may correlate with changes in the sensor's sensitivity.

[0008] Various electronic querying techniques have been developed for sensors other than electrochemical sensors (such as flammable gas sensors). For example, U.S. Patent Application Publication No. 2014 / 0273263, whose disclosure is incorporated herein by reference, discloses the periodic measurement of a variable related to the reactance of a sensing element in a flammable gas sensor for determining the operating state of the sensing element. U.S. Patent Application Nos. 15 / 597,933 and 15 / 597,859 disclose electronic querying techniques for flammable gas sensors in which a variable related to the mass of the sensing element (e.g., an electrical property such as resistance) is periodically measured to determine, for example, whether a substance such as an inhibitor or poison has been deposited on the sensing element. [Overview of the project] [Problems that the invention aims to solve]

[0009] Current testing or querying techniques are useful in determining whether individual sensors are operational at the time of testing, but they have been relatively unsuccessful in predicting future failures of such sensors. [Means for solving the problem]

[0010] summary In one embodiment, a method for operating a gas sensor for a gas analyzer including a sensing component includes, as a first mode, querying the sensor by periodically applying an electrical signal to the sensing component of the sensor, measuring the sensor response to the electrical signal indicating the sensitivity of the sensor each time the electrical signal is applied to the sensing component, determining whether one or more thresholds have been exceeded based on the sensor response determined each time the electrical signal is applied to the sensing component, and, if one or more thresholds have been exceeded, entering a second mode different from the first mode in the analysis of the sensor response to the periodically applied electrical signal.

[0011] In some embodiments, the sensor response to a periodically applied electrical signal in a second mode is analyzed to determine whether the sensor response to the periodically applied electrical signal is stable. This method may further include, for example, determining the rate of change of the sensor response during the second mode to determine whether the sensor response to the periodically applied electrical signal is stable. In some embodiments, at least one of the magnitude and direction of the rate of change of the sensor response is determined. In some embodiments, the method further includes changing one or more thresholds after determining that the sensor response to the periodically applied electrical signal is stable. It is not necessary to apply a test gas during the electronic sensor query. In this regard, the sensor response can be determined without applying a test gas to the sensor. In some embodiments, at least one of the magnitude and direction of the rate of change of the sensor response is determined.

[0012] The sensor may be, for example, an electrochemical gas sensor, and the sensing component may be, for example, the working electrode of the electrochemical gas sensor. The value of the sensor response may be determined, for example, based on at least one defined parameter of the sensor response. In some embodiments, the at least one defined parameter of the sensor response is selected from the group of maximum current peak value, area under the current curve, minimum peak value, peak-to-peak value, area under the inversion curve, baseline value of the sensor response, or one or more functions thereof (e.g., product, ratio, or more complex function of one or more such parameters). The value of the sensor response in each periodically applied electronic query may be, for example, a change from the value of at least one defined parameter of the sensor response measurement in each periodically applied electronic query, from a value determined at the time of sensor calibration.

[0013] In some embodiments, one or more thresholds of the sensor response are determined by tracking the sensor response values ​​over time and determining upper and lower thresholds for a reference behavior with respect to the sensor. In some embodiments, one or more thresholds of the sensor response are determined by tracking the sensor responses over time for a plurality of similar sensors and determining upper and lower thresholds for a group for a reference behavior with respect to the plurality of sensors. In some embodiments where group thresholds are determined, one or more other thresholds are determined by tracking the sensor response of each of the plurality of similar sensors over time and determining individual upper and lower thresholds for a reference behavior with respect to each of the plurality of similar sensors. A second mode can be entered, for example, by comparing the sensor response of each of the plurality of similar sensors with the upper and lower thresholds for the group, as well as the individual upper and lower thresholds, for each of the plurality of similar sensors.

[0014] The sensors of the multiple similar sensors described herein may exhibit, for example, at least one common characteristic other than being similar sensors. This at least one common characteristic may be, for example, the geographical area in which they are deployed or the scope of manufacture. In multiple embodiments, groups and subgroups of similar sensors may be established.

[0015] In some embodiments, data from the sensor is transmitted to a remote processor system for processing and / or analysis. In some embodiments, data or information from a second gas sensor for a second gas analyzer different from the gas analyzer, or data from a third sensor for environmental conditions, is transmitted to the gas sensor.

[0016] In another embodiment, the system comprises a sensor including a sensing component having at least one property that is sensitive to an analyte, and a circuit operably connected to the sensing component. In a first mode, the circuit is configured to periodically apply an electrical signal to the sensing component, measure the sensor's response to the electrical signal indicating the sensor's sensitivity each time the electrical signal is applied to the sensing component, and query the sensor by comparing the sensor response to one or more thresholds. The circuit is further configured to determine, based on the comparison of the sensor response to one or more thresholds, whether to enter a second mode different from the first mode in the analysis of the sensor's response to periodically applied electrical signals if one or more thresholds are exceeded.

[0017] In some embodiments, the circuit is configured to analyze the sensor response to a periodically applied electrical signal in a second mode to determine whether the sensor response to the periodically applied electrical signal is stable. The circuit may further be configured to determine the rate of change of the sensor response during the second mode, for example, to determine whether the sensor response to the periodically applied electrical signal is stable. For example, at least one of the magnitude and direction of the rate of change of the sensor response may be determined. In some embodiments, the circuit is further configured to change one or more thresholds after determining that the sensor response to the periodically applied electrical signal is stable. The circuit may be configured to determine the sensor response without applying a test gas to the sensor, for example.

[0018] In some embodiments, the sensor is an electrochemical gas sensor, and the sensor component is the working electrode of the electrochemical gas sensor. As described above, the value of the sensor response is determined based on at least one defined parameter of the sensor response. In some embodiments, the at least one defined parameter of the sensor response is selected from the group consisting of the maximum current peak value, the area under the current curve, the minimum peak value, the peak-to-peak value, the area under the inversion curve, the baseline value of the sensor response, a function, or one or more of the functions described above. The value of the sensor response in each periodically applied electronic query may be, for example, a change from a value determined at the time of sensor calibration of at least one defined parameter of the sensor response measurement in each periodically applied electronic query.

[0019] In some embodiments, one or more thresholds of the sensor response are determined by tracking the sensor response values ​​over time and determining upper and lower thresholds for a reference behavior relating to the sensor. In some embodiments, one or more thresholds of the sensor response are determined by tracking the sensor responses of a plurality of similar sensors over time and determining upper and lower thresholds for a group for a reference behavior relating to the plurality of sensors. Each of the plurality of similar sensors may include, for example, a communication system for transmitting data relating to the sensor response in response to periodically applied electronic queries and receiving data relating to upper and lower thresholds for a group for a reference behavior relating to the plurality of sensors. In some embodiments in which group thresholds are determined, one or more other thresholds are determined by tracking the sensor response of each of the plurality of similar sensors over time and determining individual upper and lower thresholds for a reference behavior relating to each of the plurality of similar sensors. A second mode may be input for each of the plurality of similar sensors based on, for example, comparing the sensor response of each of the plurality of similar sensors with the upper and lower thresholds for a group, as well as the individual upper and lower thresholds.

[0020] In some embodiments in which multiple similar sensors are tracked, each of the multiple similar sensors has at least one common characteristic other than being a similar sensor. The at least one common characteristic may be, for example, the geographical area in which they are deployed or the range of manufacturing time.

[0021] Data from the sensor may be transmitted, for example, to a remote processing system for processing and / or analysis. Data or information from a second gas sensor for a second gas analyzer different from the gas analyzer, or data from a third sensor for environmental conditions, may be transmitted to the gas sensor.

[0022] In a further embodiment, a method for operating a system comprising a plurality of similar gas sensors, each of the plurality of similar gas sensors comprising a sensing component, wherein in a first mode, each of the plurality of similar gas sensors is queried by periodically applying an electrical signal to the sensing component of the sensor, each time the electrical signal is applied to the sensing component, a sensor response to the electrical signal indicating the sensitivity of each of the plurality of similar gas sensors is determined, and the sensor response of each of the plurality of similar gas sensors to the periodically applied electrical signal is analyzed based on a reference response of the plurality of similar gas sensors to the periodically applied electrical signal, which is determined over time. This method may further include, for example, determining for each of the plurality of similar gas sensors whether, in the analysis of the sensor response to the periodically applied electrical signal, it enters a second mode different from the first mode, based on a comparison of the sensor response of each of the plurality of similar gas sensors with the reference response of the plurality of similar gas sensors in the first mode. This method may be further characterized as described above.

[0023] In yet another aspect, the system includes a plurality of similar gas sensors, each of the plurality of similar gas sensors including a sensing component and an electronic circuit operable with the sensing component. The electronic circuit, in a first mode, interrogates each of the plurality of similar gas sensors by periodically applying an electrical signal to the sensing component of the sensor, measures a sensor response to the electrical signal indicative of sensitivity for each of the plurality of similar gas sensors each time the electrical signal is applied to its sensing component, and analyzes the sensor response to the periodically applied electrical signal based on a reference response of the plurality of similar gas sensors to the periodically applied electrical signal determined over time. The electronic circuit of each of the plurality of similar sensors can be further configured to determine whether to enter a second mode, different from the first mode, in the analysis of the sensor response to the periodically applied electrical signal, based, for example, on a comparison of the sensor response to the reference response of the plurality of similar gas sensors in the first mode. The system can be further characterized as described above.

[0024] The apparatus, system, and method, together with their attributes and attendant advantages, will be best recognized and understood when considered in conjunction with the following detailed description, taken in conjunction with the accompanying drawings.

Brief Description of the Drawings

[0025] [Figure 1A] FIG. 1A is a diagram schematically showing an embodiment of the electrochemical sensor of the present specification. [Figure 1B] FIG. 1B is a schematic circuit diagram of an embodiment of the sensor of the present specification. [Figure 1C] FIG. 1C is a diagram showing a representative response to an electronic interrogation of an electrochemical gas sensor. [Figure 1D] FIG. 1D is a diagram showing the response of FIG. 1C on an enlarged scale. [Figure 2] FIG. 2 is a diagram showing the change in the sensor response (maximum peak (current) value or MPV) to an electronic interrogation over time after initial calibration. [Figure 3]Figure 3 shows the change in sensor response (MPV) to electronic queries over time for multiple sensors after initial calibration. [Figure 4] Figure 4 shows the changes in the sensor response (shown as the difference between the change in MPV and the average change in MPV) to electronic queries over time for multiple sensors after initial calibration. [Figure 5] Figure 5 shows the change in the sensor response (MPV) to electronic queries over time for a single sensor after initial calibration. It temporarily falls below the threshold of a standard deviation of -3, but then recovers. [Figure 6] Figure 6 shows the changes in the sensor response (expressed as the difference between the change in MPV and the average change in MPV) to electronic queries over time for multiple sensors after initial calibration. One of the sensors' outputs changes in a different manner than the others, but the output remains within the reference range. [Figure 7] Figure 7 shows a typical embodiment of a system for data communication, processing, and analysis of sensor data from one or more facilities or locations. [Modes for carrying out the invention]

[0026] Detailed explanation It will be readily apparent that the components of the embodiments generally described and illustrated in the figures of this specification may be arranged and designed in a wide range of different configurations in addition to the representative embodiments described. Accordingly, the following more detailed description of representative embodiments as shown in the figures is not intended to limit the scope of specific examples claimed, but merely to illustrate representative embodiments.

[0027] In this specification, when we refer to “one embodiment” or “one embodiment” (or similar), we mean that certain features, structures, or characteristics described in relation to the embodiment are included in at least one embodiment. Accordingly, the occurrence of the phrase “in one embodiment” or “in one embodiment” in various parts of this specification does not necessarily refer to the same embodiment.

[0028] Furthermore, the described features, structures, or properties may be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a full understanding of the embodiments. However, those skilled in the art will understand that various embodiments can be carried out without using one or more of the specific details, or using other methods, components, materials, etc. In other examples, well-known structures, materials, or operations are not shown or described in detail to avoid obscurity.

[0029] Where used herein and in the appended claims, the singular nouns (a, an) and (the) include plural references unless otherwise explicitly indicated in the context. Thus, for example, a reference to “processor” includes multiple such processors and their equivalents known to those skilled in the art, while a reference to “the processor” refers to one or more such processors and their equivalents known to those skilled in the art. The detailed descriptions of value ranges herein are intended merely as a simplified method for individually referring to each distinct value falling within the range. Unless otherwise stated herein, each distinct value and intermediate range are incorporated herein as if they were individually described herein. All methods described herein may be performed in any suitable order unless otherwise indicated herein or unless otherwise explicitly stated herein.

[0030] As used herein, the terms “electronic circuit,” “electronic circuit,” or “circuit” include, but are not limited to, hardware, firmware, software, or a combination thereof for performing a function or operation. For example, based on the desired function or needs, a circuit may include discrete logic (circuits) such as a software-controlled microprocessor or an application-specific integrated circuit (ASIC), or other programmed logic devices. A circuit may also be fully embodied as software. As used herein, “circuit” is considered synonymous with “logic.” As used herein, the term “logic” includes, but are not limited to, hardware, firmware, software, or a combination thereof for performing a function or operation, or for causing a function or operation from other components. For example, based on the desired application or needs, logic may include individual logic such as a software-controlled microprocessor or an application-specific integrated circuit (ASIC), or other programmed logic devices. Logic may also be fully embodied as software.

[0031] As used herein, the term “processor” includes, but is not limited to, any combination of one or more processor systems or standalone processors, such as microprocessors, microcontrollers, central processing units (CPUs), and digital signal processors (DSPs). A processor may be associated with various other circuits that support the operation of the processor, such as random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), clock, decoder, memory controller, or interrupt controller. These supporting circuits may be inside or outside the processor or its associated electronic packaging. The supporting circuits communicate operationally with the processor. The supporting circuits are not necessarily shown separately from the processor in block diagrams or other drawings.

[0032] As used herein, the term “controller” includes, but is not limited to, any circuit or device that coordinates and controls the operation of one or more input and / or output devices. A controller may include, for example, a device having one or more processors, microprocessors, or central processing units that can be programmed to perform functions.

[0033] As used herein, the term “logic” includes, but is not limited to, hardware, firmware, software, or combinations thereof used to perform a function or operation, or to cause a function or operation from another element or component. Depending on the specific application or needs, logic may include, for example, individual logic such as a software-controlled microprocess, an application-specific integrated circuit (ASIC), or other programmed logic devices. Logic may also be fully embodied as software. As used herein, the term “logic” is considered synonymous with the term “circuit.”

[0034] As used herein, the term “software” includes, but is not limited to, one or more computer-readable or executable instructions that cause a computer or other electronic device to perform functions, operations, or behaviors in a desired manner. Instructions can be embodied in various forms, such as routines, algorithms, modules, or programs that include separate applications or code from dynamically linked libraries. Software can also be implemented in various forms, such as standalone programs, function calls, servlets, applets, instructions stored in memory, parts of an operating system, or other types of executable instructions. It will be understood by those skilled in the art that the form of software depends, for example, the requirements of the desired application, the environment in which it will be run, or the desires of the designer / programmer, etc.

[0035] Some embodiments of this specification are described in relation to electrochemical gas sensors and their electronic querying. However, the apparatus, systems, and methods of the present invention are applicable to any type of sensor in which diagnostic testing or electronic querying of the sensing components is performed.

[0036] As mentioned above, recent developments for electronic querying of electrochemical sensors have reduced the need for frequent calibration with test gases. In electronic querying, an electrical signal is applied to a sensing component of the sensor that interacts with the target or analyte gas. For example, an electrical signal may be applied to the working electrode of an electrochemical sensor which includes an electrocatalyst that catalyzes a reduction or oxidation reaction with the analyte gas. Similarly, an electrical signal may be applied to the sensing element of a flammable gas sensor, which may or may not include a catalyst that, when the sensing element is heated to a suitable temperature, promotes the combustion of the sensing gas (for example, by providing a reaction pathway with a lower activation energy than a reaction without a catalyst).

[0037] In the case of electrochemical gas sensors, the electronic query can be for a fairly short time, for example, to minimize the total time the sensor is offline performing sensor test diagnostics (i.e., during the sensor electronic query cycle). For example, in some representative embodiments of electrochemical gas sensor devices, systems, and / or methods for electronic querying, it may be possible to return to normal (gas sensing) mode operation for the electrochemical sensors herein in less than 10 seconds, less than 5 seconds, or less than 1 second. Devices, systems, and methods for electronic querying sensors not only allow an instrument containing one or more sensors to remain “online,” but also provide active, automated sensor status monitoring as background operation without the need for user activation. The electronic queries herein are performed periodically. As used herein, the term “periodic” refers to electronic queries that occur from time to time or multiple times over time, but not necessarily at fixed intervals or frequencies. The frequency of electronic queries may be constant or vary. For example, providing sensor queries at a frequency of several times per hour can provide monitoring of a nearly constant sensor life and health status.

[0038] In electrochemical gas sensors, the gas to be measured typically passes through the sensor housing from the ambient atmosphere or environment, via a gas-porous or gas-permeable membrane, to a first electrode or working electrode (also called the sensing electrode) where a chemical reaction takes place. A complementary chemical reaction occurs at a second electrode known as the counter electrode (or auxiliary electrode). The electrochemical sensor generates an analytical signal through the generation of an electric current, which arises directly from the oxidation or reduction of the analyte gas (i.e., the gas being detected) at the working electrode. A comprehensive description of electrochemical gas sensors is also provided in Cao, Z. and Stetter, JR, “The Properties and Applications of Amperometric Gas Sensors,” Electroanalysis, 4(3), 253 (1992), the disclosure of which is incorporated herein by reference.

[0039] The combination of the working electrode and the counter electrode generates an electrical signal that is (1) related to the concentration of the analyte gas and (2) strong enough to provide a signal-to-noise ratio suitable for distinguishing concentration levels of the analyte gas over the entire range of interest. In other words, the current flow between the working electrode and the counter electrode must be measurably proportional to the concentration of the analyte gas over the target concentration range.

[0040] In addition to the working electrode and counter electrode, electrochemical sensors often include a third electrode, commonly referred to as a reference electrode. The reference electrode is used to maintain the working electrode at a known voltage or potential. The reference electrode should be physically and chemically stable in the electrolyte.

[0041] The electrical connection between the working electrode and the counter electrode is maintained via an electrolyte. The functions of the electrolyte include (1) efficiently carrying ionic current, (2) solubilizing the analyte gas, (3) supporting both the reaction of the counter electrode and the working electrode, and (4) forming a stable reference potential with the reference electrode. Criteria for the electrolyte include, for example, (1) electrochemical inertness, (2) ionic conductivity, (3) chemical inertness, (4) temperature stability, (5) low cost, (6) low toxicity, (7) low flammability, and (8) appropriate viscosity.

[0042] Generally, the electrodes of an electrochemical cell provide a surface on which oxidation or reduction (oxidation-reduction) reactions occur, thereby providing a mechanism in which the ionic conduction of the electrolyte solution combines with the electron conduction of the electrodes, providing a complete circuit for electric current. The measurable current resulting from the cell reaction in an electrochemical cell is directly proportional to the degree of reaction occurring at the electrodes. Therefore, preferably, a high reaction rate is maintained within the electrochemical cell. For this reason, the counter electrode and / or working electrode of an electrochemical cell generally contain a suitable electrode catalyst on its surface to support the reaction rate.

[0043] As a result of electrostatic forces, the volume of solution very close to the working electrode surface becomes a highly ordered structure. This structure is important for understanding the electrode process. The volume of solution very close to the electrode surface is variously referred to as the diffusion layer, diffuse layer, and / or Helmholtz layer, or plane.

[0044] The magnitude of resistance and capacitance present in an electrochemical cell is a result of the properties and identity of the materials used in its manufacture. The resistance of the electrolyte is a result of the number and types of ions dissolved in the solvent. The capacitance of the electrode is primarily a function of the effective surface area of ​​the electrode catalyst. Ideally, these quantities are invariant. However, the solution resistance present in a current measuring gas sensor utilizing an aqueous (water-based) electrolyte can change, for example, as a result of exposure to different ambient relative humidity levels. As water evaporates from the sensor, the chemical concentration of the ionic electrolyte increases. This concentration change can result in an increase or decrease in the resistivity of the electrolyte, depending on the electrolyte actually used.

[0045] Furthermore, even substances that are normally considered insoluble in certain solvents still exist in small but finite concentrations within the solvent. For example, the concentration of metal from electrodes dissolved in the electrolyte of an electrochemical sensor is very small but finite. This small concentration of dissolved metal is constantly flowing; that is, metal atoms are constantly dissolving from the electrodes and being re-plated somewhere else. The net effect of this process is a reduction in the effective surface area of ​​the electrodes. This has the effect of decreasing the sensor capacity over time. Both of the above effects have a net effect of changing the sensitivity of the sensor over its entire lifespan.

[0046] Figure 1A shows a schematic diagram of a typical embodiment of an electrochemical sensor 10 that may be used in the apparatus, systems, and methods of this specification. The sensor 10 includes a housing 20 having a gas inlet 30 for introducing one or more target gases or analyte gases into the sensor 10. In the illustrated embodiment, electrolyte saturated wick materials 40a, 40b, and 40c separate the working electrode 50 from the reference electrode 70 and counter electrode 80 in the sensor 10 and / or provide ionic conduction between them via the electrolyte 44 in the housing 20 and are absorbed within the wick materials 40a, 40b, and 40c. Electronic circuits 100 known in the art are provided, for example, to maintain a desired potential difference between the working electrode 50 and the reference electrode 70, to change or pulse the potential difference as described herein, and to process the output signal from the sensor 10.

[0047] In the illustrated embodiment, the working electrode 50 may be formed, for example, by depositing a first layer of catalyst 54 on a diffusion membrane 52 (for example, using catalyst deposition techniques known in sensor technology). The gas is readily transferred or transported through the diffusion membrane 52 (for example, by diffusion), but the electrolyte 44 is not readily transferred or transported through the diffusion membrane 52. The working electrode 50 may be attached to the inner surface of the top, cap, or lid 22 of the housing 20 (for example, via a heat seal).

[0048] The electronic circuit 100 may include a processor or controller system 102, for example, one or more processors or microprocessors for controlling various modes of operation of the sensor 10. A memory system 104 may be located in an operational or communicative connection to the processor system 102 and may store software for controlling the sensor 10 and / or analyzing its output, as described herein. A user interface system (including, for example, a display, speaker, etc.) may also be located in an operational or communicative connection to the processor system 102. A communication system 108, such as a transceiver, may be located in an operational or communicative connection to the processor system 102 for wired and / or wireless communication. A power supply 110 (e.g., a battery system) may supply power to the electronic circuit 100.

[0049] Figure 1B schematically shows one or more embodiments of an electronic or control circuit 100 used in some studies of the sensor of the present invention. The portion of the electronic circuit 100 shown in Figure 1B is also referred to as a constant potential circuit. In a three-electrode sensor as shown in Figure 1A, a predetermined potential difference or voltage is maintained between the reference electrode 70 and the sensing electrode or working electrode 50 to control an electrochemical reaction and to send an output signal proportional to the current generated by the sensor. As described above, the working electrode 50 responds to the analyte gas or target gas by oxidizing or reducing the gas. The redox reaction generates a current proportional to the gas concentration. The current is supplied to the sensor 10 via the counter electrode 80. A redox reaction opposite to the reaction at the working electrode occurs at the counter electrode 80, completing the circuit with the working electrode 50. The potential of the counter electrode 80 may float. When a gas is detected, the cell current rises and the counter electrode 80 is polarized relative to the reference electrode 70. The potential of the counter electrode 80 is not important as long as the circuit provides sufficient voltage and current to maintain the correct potential of the working electrode 50.

[0050] For example, as described in U.S. Patent Application Publication No. 2017 / 0219515, in some representative embodiments, the measurement circuit of the electrical / electronic circuit 100 includes a single-stage operational amplifier, i.e., op-amp IC 1. The sensor current is reflected by a gain resistor 120 (having a resistance of 5 kΩ in the illustrated embodiment) to generate an output voltage. The load resistor 122 (having a resistance of 56 Ω in the illustrated embodiment) may be selected, for example, through a balance between the fastest response time and the best signal-to-noise ratio.

[0051] The control operational amplifier IC2 provides constant potential control and supplies current to the counter electrode 80 to balance the current required by the working electrode 50. The inverting input to IC2 is connected to the reference electrode, but no significant current flows from the reference electrode.

[0052] During electronic querying of an electrochemical gas sensor according to this specification, such as sensor 10, a non-Faraday current may be induced (e.g., via the application of energy to the working electrode 50). For example, an electrical signal may be applied to the working electrode 50 to generate a stepwise change in potential that produces a non-Faraday current. The generated non-Faraday current may be used to monitor the operating state, functionality, or health of the sensor as a result of charging the electrodes. However, as described above, the sensor is then returned to its normal bias potential or potential range for normal operation when sensing a target or analyte gas. The process of returning the sensor to its operating bias or operating potential difference (which may be zero) generates a current peak (charge accumulation) in the opposite direction. The current peak generated when returning to the operating potential difference may take several seconds to dissipate.

[0053] Information regarding the health, operating state, or operating conditions of a sensor can be obtained, for example, from the response to electronic queries measured in the form of: (i) Maximum Peak Value (MPV), which is the maximum current observed when a potential pulse is applied; (ii) Area Under Curve (AUC), which is the integral current response of the working electrode after the application of a potential pulse (this corresponds to the sensor's charging response); (iii) Minimum Peak Value (mPV), which is the minimum current obtained when the potential pulse is removed or reversed, and is usually obtained as the difference between the currents observed immediately before and after the removal or reversed potential pulse, and may also be used in a table as the difference between the minimum current and the baseline; (iv) Inter-Peak Value (PP), which is the algebraic difference between the maximum and minimum observed currents; (v) Inverted Area Under Curve (rAUC), or more precisely, the inverse area under curve, which is the charging current obtained by integrating the current response after the removal or reversed potential pulse; and (vi) Change in baseline or baseline output and its function thereto (e.g., product, ratio, and / or more complex function of one, two, or more such parameters). The operating status of the sensing components (e.g., the working electrode of an electrochemical gas sensor, or the sensing element of a flammable gas sensor) and the sensor / sensor device is typically determined by relating such parameters and / or other parameters to changes in the sensor's sensitivity. Sensitivity refers to the ratio of the output signal (e.g., current) to the measured physical quantity (e.g., concentration of the analyte or target gas).

[0054] Measuring / analyzing a single or multiple data points over a short period of time provides response / current versus time curves for a typical electrochemical gas sensor for hydrogen sulfide or H2S, for example, as shown in Figures 1C and 1D. The rapid discharge of the relatively large current peak that occurs when inducing a non-Faraday current in sensor 10 (or another sensor herein) and / or when returning sensor 10 (or another sensor herein) to its operating potential difference can also be achieved via active control of the sensor electronics or electronics circuit 100 (e.g., by reducing the load resistance of electronics circuit 100 between the working electrode 50 and the point where the output / response is measured after the test potential difference is applied). In some embodiments, the load resistance between the working electrode 50 and the output of op-amp IC1 is reduced to a low value. Subsequently, the load resistance between the working electrode 50 and the output of op-amp IC1 is restored to its normal resistance or operating load resistance (or within the operating range of the load resistance) after the charge has substantially or completely dissipated.

[0055] In some embodiments, the load resistor 122 (see Figure 1B) is bypassed to reduce the load resistance between the operating electrode 50 and the inverting terminal of the operational amplifier IC 1. A bypass circuit 124 may be provided, for example, to bypass the load resistor 122. In some embodiments, a field-effect transistor (FET) 126 was used as a switch in the bypass circuit 124 to allow controllable bypass or short circuit around the load resistor 122. In some embodiments, a metal oxide semiconductor FET or MOSFET was used.

[0056] Figures 1C and 1D show the output of a typical sensor 10, including a working electrode 50 designed to detect hydrogen sulfide or H2S. In the embodiments studied in Figures 1C and 1D, the working electrode 50 was formed by depositing an iridium catalyst onto a diffusion film, the reference electrode 70 was formed by depositing an iridium catalyst onto a diffusion film, and the counter electrode 80 was formed by depositing an iridium catalyst onto a diffusion film. The bias potential or operating potential difference of the sensor was 0 mV. As illustrated in Figure 1C, the electronic querying procedure is initiated at point A. After 0.5 seconds (indicated by point B), the test potential difference is applied. In the illustrated study, a test potential of +10 mV was applied. The maximum peak value (MPV) of the output was recorded 1 / 16 second after the application of the test potential, as indicated by point C. At that point, the potential was also returned to an operating potential difference of 0 mV. When the load resistor 122 was bypassed, FET 126 was activated almost simultaneously with, or simultaneously with, the return of the potential to the operating potential difference. When the load resistance is quite low, a large negative current spike occurs (which corresponds to a very high negative gas ppm reading in normal operating mode). However, the rapid discharge that occurs when bypassing the load resistor 122 brings the sensor output back to baseline in a very short time (i.e., less than 1 second). Figure 1D is scaled up to illustrate this result. However, if the load resistor 122 is not bypassed, it takes several seconds for the output to return to the baseline output. As shown in Figure 1C, when FET 126 is deactivated as represented by point D, and the 56Ω load resistor 122 is restored to the circuit in approximately 0.95 seconds, the output current falls below a value identified by the end user. This value is typically in the range of approximately 0 to ±2 ppm of the target gas.

[0057] Information regarding the health or state of the sensor may be obtained, for example, when an electrical signal is applied in the form of an extremely small and / or short-duration electrode potential change, and when measuring / analyzing a single or multiple data points over a short time span in the resulting response / current curve, such as the maximum peak current (MPV) value and / or other parameters described above. In some representative embodiments herein, the MPV is used to characterize the sensing element / working electrode of the electrochemical sensor. As described above, the rapid discharge of the relatively large current peak that occurs when inducing a non-Faraday current in sensor 10 (or another electrochemical sensor herein) and / or when returning sensor 10 (or another sensor herein) to its operating potential difference can be achieved through active control of the sensor electronics / electronics 100 (e.g., by reducing the load resistance of electronics 100 between the working electrode 50 and the point where the output / response is measured after the test potential difference is applied). In some embodiments, the load resistance between the working electrode 50 and the output of op-amp IC1 is reduced to a low value. Next, the load resistance between the working electrode 50 and the output of the operational amplifier IC1 is restored to its normal resistance or operating load resistance (or within the operating range of the load resistance) after the charge has been substantially or completely dissipated.

[0058] For example, fluctuations in the sensitivity of an electrochemical sensor as a result of moisture loss or increase occur gradually, but generally in a predictable manner as the mean relative humidity changes slowly. Sensor responses to electronic queries without gas, as described above, also change similarly. Electronic queries can be used to track and compensate for changes in sensitivity, as described, for example, in U.S. Patent Nos. 7,413,645, 7,959,777, 9,784,755, and 9,528,957, and U.S. Patent Application Publications 2013 / 0186777 and 2017 / 0219515. As described above, potential pulses are typically applied to the sensing components of the sensor, and the resulting responses are recorded, for example, in the form of a maximum peak (current) value and / or one or more other parameters. These responses can be compared to values ​​obtained during previous gas tests / pulse cycles. Changes from calibration values ​​correlate with changes in operating state / sensor sensitivity. In this way, the health of the sensor at the time of query is evaluated. Then, the sensitivity can be adjusted to compensate for such changes. This method provides a real-time status of the sensor's health at the time of query, but it does not account for future sensor performance.

[0059] In some embodiments of the apparatus, systems, and methods herein, a series of consecutive query events are performed in a first mode or first query mode, for example, to determine whether the sensor response to an electronic query is outside the range of a reference operating range. For example, changes in the values ​​of one or more parameters, such as MPV, AUC, and / or other parameters, or determined from them, may be used to evaluate whether the sensor requires further / modified analysis and / or maintenance. If, for example, the sensor response to a query is outside the range of a reference, normal, or expected variation (e.g., a normal variation expected as a result of gradually changing relative humidity), the sensor may be identified or flagged as requiring attention.

[0060] In some embodiments of this specification, if the sensor exhibits a response to an electronic query outside a criterion range for the response, a second mode, a second query mode, or an observation mode is entered. In the second mode, the analysis of the sensor response to the electronic query differs from that of the first mode. In the second mode, the sampling rate of one or more parameters may be changed, and / or the identification of one or more measured parameters may be changed. In some embodiments, if the sensor response to the electronic query is stable or stabilized, the determination is made over one or more periods from the response measured in the second mode to a periodic electronic query (i.e., multiple electronic queries over time). For example, it may be determined over one or more periods in the second mode whether the sensor response is approaching an average rate of change within a predetermined threshold over one or more periods in the second mode, or whether it remains within a predetermined or defined response range over one or more periods in the second mode. In some embodiments, the rate of change of a measured variable (based on or derived from one or more parameters) may be determined over one or more periods in a second mode, for example, to determine whether the sensor response is stable. The determination regarding sensor response stability (e.g., determined from the magnitude / direction of the rate of change over one or more periods in a second mode) may be used to determine, for example, whether the sensor settings should be changed (e.g., changing the range of the response criteria, changing the sensitivity correction, etc.), whether the sensor needs to be recalibrated, or whether the sensor needs to be replaced. In the apparatus, systems, and methods described herein, the health or operating state of the sensor (i.e., sensitivity) is measured during electronic queries, and its future health state is estimated using a set of health measurements (i.e., measured responses to electronic queries).

[0061] The reference range of the sensor response to electronic queries can be derived in several ways. A simple way to determine the reference range of the response is to track the sensor response over a period of time and determine the reference or normal variation. Then, limits (e.g., upper and lower thresholds) can be set to identify or flag deviations in the sensor operation. Such limits may be re-determined over time, for example, as further electronic queries are performed. The reference limit or threshold, and whether such a reference limit has been exceeded (thus triggering the input of a second mode), may be determined, for example, via software stored in the memory system 104 and executable by the processor system 102. Figure 2 shows an example plotting the change in MPV value from the initial calibration point (at time of manufacture) over more than 80 days.

[0062] In Figure 2, the sensor exhibiting baseline behavior is labeled sensor 10a(i). In the results of Figure 2, the mean over 80 days is 26 counts, and the standard deviation is 107 counts. Limit values ​​or thresholds can be set, for example, using multiples of the standard deviation (e.g., sigma from ±1 to ±3). In the illustrated embodiment, the limit values ​​were set using ±3 times the standard deviation, capturing 99.7% of the baseline distribution. Such limits (upper and lower thresholds) are shown by the upper and lower dashed traces in Figure 2. In the first mode described above, the delta MPV is tracked over time and compared to the baseline delta MPV value (upper and lower thresholds for the baseline delta MPV value). Once the delta MPV moves beyond one of these limits, the system can enter, for example, a second mode or observation mode, where the analysis of responses to electronic queries differs from that in the first mode. As described above, the rate of change of delta MPV may be tracked over one or more periods in the second mode to determine whether the sensor response to the electronic query is stabilizing. Thus, in some embodiments of the second mode, the electronic query continues as described above, and the delta MPV is still tracked, but the rate of change of delta MPV (dΔMPV / dt) is also tracked.

[0063] Figure 2 shows two representative examples of tracking the rate of change of delta MPV. The data trace of sensor 10a(ii) shows that the sensor has experienced a stepwise change in the MPV value. Once the delta MPV exceeds the -3 sigma value / limit, the rate of change is monitored in the second operating mode as described above. Furthermore, a warning or notification may be provided to the user to alert the user that the sensor has entered the second mode (but is not required). However, the user does not need to take any action at that point. Providing the second mode or observation mode described herein may offer significant advantages by reducing the interaction required of the user compared to currently available sensors by reducing unnecessary bidirectional maintenance. Depending on the control software stored in the sensor's memory system 104, the sensor may, for example, change compensation, increase the frequency of pulse / electronic query tests, measure one or more additional parameters, and change the range of the reference sensor response in the second mode. Such operations may, for example, be automated or may not require user intervention.

[0064] For a sensor whose response to an electronic query is found to stabilize in a second mode (e.g., via an electronic or electrical circuit 100), the response may stabilize within the original range of a reference response, another range of the reference response, or an offset range of the reference response. One or more limits or thresholds for an acceptable response / reference response may be defined for the sensor. If the sensor stabilizes within a response range that exceeds such limits or thresholds, the sensor may be flagged for service or replacement, for example. For sensor 10a(ii), the rate of change is stable, and the system predicts that the future state of sensor 10a(ii) will be stable within a new acceptable reference range, although offset from the original range or reference response. The system may trigger, for example, a “recalibrate sensor” display or warning, and / or reset the system to the new state. For a “new” calibration, for example, the sensor may determine the delta MPV from a new “anchor” value determined during the new calibration. Additionally, the sensor may continue to determine its delta MPV from the factory calibration (either alternatively or additionally).

[0065] On the other hand, the data trace of sensor 10a(iii) indicates a catastrophic failure of sensor 10a(iii). Again, when the delta MPV exceeds the -3 sigma lower limit, the rate of change can be monitored, for example, in the second mode over one or more time periods to determine whether the sensor response to electronic queries will stabilize. In the case of sensor 10a(iii), the sensor response (delta MPV in this example) continues to change rapidly, and the system predicts that sensor 10a(iii) will rapidly move away from its useful state for gas detection. The system may trigger, for example, a "sensor replacement" warning. After such a decision has been made, quantification may be performed, and a warning may be provided to take the sensor out of operation permanently or for a certain period (e.g., 24 hours or several days) if repair is possible. If the period of downtime is excessively dangerous or burdensome, the sensor may be replaced during that period.

[0066] The scope of the “group” criterion for responses to electronic queries can also be determined by a data distribution across a group of sensors (e.g., multiple similar sensors) that can share at least one common characteristic, other than being similar sensors. As used herein, the term “similar” refers to sensors manufactured in a similar or identical manner. Generally, such sensors are manufactured to sense the same analyte and include sensing components manufactured in the same manner. For example, a similar electrochemical gas sensor for a particular gas analyte may include a working electrode manufactured in a similar manner and may include the same electrolyte. The counter electrode, reference electrode, and / or electronic circuit of such a sensor may also be manufactured in a similar or identical manner. Such an electrochemical gas sensor may be, for example, two or three electrode sensors known in the art. A similar flammable gas sensor may include, for example, a sensing element, a compensating element, and / or electronic circuit manufactured in a similar or identical manner.

[0067] Regarding common characteristics (other than being similar sensors), a group of sensors may share, for example, the same local environment and / or a common range of manufacturing dates. Such sensors may be all units used in the same location for a particular customer, or all units used in a wider area (e.g., a city or county). The distribution may also be based, for example, on sensor manufacturing date codes and may cover global and / or localized populations. Groups and subgroups of similar sensors may be established based on different shared or common characteristics. The results for each unit may be aggregated, and the distribution of the entire population may be used as a baseline dataset.

[0068] Figure 3 shows a typical example of data from 15 sensors in the same local environment. As mentioned above, the change in MPV value from the initial calibration point is plotted for all sensors over 80 days or more. The mean value over 80 days or more was 5 counts, and the standard deviation was 117 counts. In the typical example in Figure 3, group limits or thresholds can be established, for example, using multiples of sigma. In the illustrated embodiment, upper and lower thresholds for the group were established using ±3 times the standard deviation, capturing 99.7% of the reference distribution. Group limits can be determined, for example, via an external processor system of multiple similar sensors that communicates with each of the multiple similar sensors and receives data / information from them. The determined group limits can be transmitted, for example, from the external processing system to each of the multiple similar sensors. Such group limits are shown in Figure 3 by the upper and lower dashed lines. When the measured delta MPV for a particular sensor moves beyond these limits, the sensor system can enter a second mode or observation mode. As described above, in some embodiments, the rate of change of the delta MPV may be tracked for the sensor in the second mode to determine whether the sensor response is stable. Similar to Figure 2, two examples of sensor step change (sensor 10a(ii)) and catastrophic sensor failure (sensor 10(iii)) are shown in Figure 3. Actions for such individual sensors (e.g., adjustment of the reference threshold, or initiation of notifications / warnings such as “recalibration warning” and “replace sensor” warnings) may be the same as those described above in relation to the single sensor example in Figure 2, for example.

[0069] Referring again to Figure 3, it is clear that the local population of studied sensors responds in a manner similar to the daily changes in the local environment. This result suggests an additional step: using local population data, compare the daily delta MPV value of each sensor to the daily average delta MPV for all sensors within that local population. In this way, the behavior of the baseline with respect to the population is normalized for each query event, and deviations from the behavior of the baseline become clearer. Figure 4 illustrates this method. The mean over 80 days is 0 counts, however the standard deviation is only 55 counts. Here again, we can set group limits by using ±3 times the standard deviation to capture 99.7% of the baseline distribution. These are shown by the dotted lines in Figure 4. This data processing removes some of the daily noise in the delta MPV values ​​and makes it easier to distinguish two deviated cases from other sensors.

[0070] Some sensors may exhibit some inherent noise compared to the general population. Sensors flagged by the group processing described in relation to Figure 3 (i.e., when comparing sensor responses to one or more electronic queries against a group limit or threshold determined for a group / multiple similar sensors) are still performing above reference when compared to their own history (i.e., when comparing sensor responses to one or more electronic queries against individual limits or thresholds determined for individual sensors). In other cases, the processing described in relation to Figure 3 can be combined with the single-sensor processing described in relation to Figure 2. In a typical example in Figure 4, sensor 10a(iv) shows several instances below the -3 standard deviation / threshold line for the monitored group / multiple similar sensors. Sensor 10a(iv) may be identified as flagged for a single action or evaluation for follow-up, for example. Figure 5 shows single-sensor processing for sensor 10a(iv) (e.g., as described in relation to Figure 2 above). As shown in Figure 5, sensor 10a(iv) temporarily falls below the -3 standard deviation limit for individual sensors, but then recovers. By combining both the group, population, or distribution processing described in the specification and the individual sensor processing, a more comprehensive evaluation can be obtained, and sensor 10a(iv) may be considered to be functioning properly, for example.

[0071] For example, when evaluating trends in a group of similar sensors that share at least one common characteristic (i.e., a common characteristic other than being similar sensors, e.g., geographical location, manufacturing date range), data analysis beyond determining whether a measurement is outside a criterion range may be performed. For example, a particular sensor may be expected to stabilize or follow a certain trend (based on data from the sensor population), but it may be expected that a particular sensor may exhibit different outputs from its peers or other sensors within the monitored population. Such differences may be indicated in ways other than, for example, the output of a specific value / parameter (e.g., MPV or delta MPV) within a threshold range (e.g., outside + / - 3 standard deviations). For example, the magnitude of the response, the magnitude of the rate of change, and / or the direction of change of each sensor relative to its peers can be determined / analyzed. As shown in Figure 6, sensor 10a(v) shows a rate of change of delta MPV in the opposite direction to the other sensors in the surveyed population. Sensor 10a(v) may be identified or flagged and placed in a second mode or observation mode for further / alternative analysis and / or evaluation based on such trends, different from its peers, even if the delta MPV behavior for the sensor population and / or individual sensor 10a(v) is within a standard range.

[0072] In some embodiments, for example, if it is determined in a second mode that a particular sensor should be recalibrated and / or that the response range of its criterion should be offset by at least a defined amount or a predetermined amount from the range of the criterion of the population / similar sensors to which the particular sensor is a member, then it may be determined, for example, that the particular sensor should not be tracked as a member of the population / similar sensors. If the particular sensor stabilizes within the range of the criterion of the population / similar sensors or is slightly offset from them, then it may be determined, for example, that the particular sensor should continue to be tracked as a member of the population / similar sensors, and its response may continue to be taken into consideration when determining the threshold of the criterion for the group of population / similar sensors.

[0073] When monitoring a population / multiple similar sensors, a sensor response or response trend that differs from its peers or other sensors within the monitored population / multiple similar sensors may not necessarily indicate that the sensor in question is malfunctioning, but rather that it should not be a member of the monitored population / multiple similar sensors. Such different responses may arise, for example, from different microenvironments at a particular location. For instance, a sensor in the monitored population / multiple similar sensors exhibiting a different response / trend may be located within a structure at a particular location, while other sensors in the population / multiple similar sensors may be located outside a door. Similarly, a sensor in the monitored population / multiple similar sensors exhibiting a different response / trend may be located in direct sunlight, while other sensors in the population / multiple similar sensors are not. Thus, a sensor response that differs from the response of its peers in the population / multiple similar sensors may trigger an investigation into whether the sensor should be properly included in the population / multiple similar sensors. For example, it may be determined that the sensor under investigation should only be monitored individually or within a different population / multiple similar sensors.

[0074] In addition to providing further information / guidance when analyzing one or more sensor responses, tracking the responses of a population / multiple similar sensors to periodic electronic queries can provide information about systematic problems with the sensors in the population / multiple similar sensors. Such sensors may have been manufactured, for example, within a determined date / time or manufacturing code range. Certain defects (e.g., defects in electrolyte composition) may not be detected at the time of manufacture but can lead to abnormal responses to subsequent electronic queries. Tracking the responses of multiple similar sensors to electronic queries in this way can lead to the detection of systematic problems with the sensors, for example, even before such defects become apparent in other ways.

[0075] Changes in the maximum peak value and / or one or more other parameters from the time of manufacture of the sensor (and / or from another starting point or anchor point, such as the next calibration) to the later stages of the sensor's lifespan can be analyzed, for example, to determine the type of environmental conditions (e.g., low humidity or dry conditions) the sensor experienced during that historical period. Based on such historical data, one or more parameters of the sensor operation can be modified. Software algorithms stored in memory and executable by one or more processors can, for example, apply different temperature compensation. The algorithms can, for example, apply different sensitivity compensation based on such historical data. The algorithms herein (based on such historical data) can, for example, be used to modify the reference response range based on such historical data.

[0076] Data from sensors that are not similar, or from sensors with characteristics very different from one or more sensors being monitored / analyzed, may also be used to determine the operating state of sensors in the apparatus, systems, and methods of this specification. Such sensors that are not similar may, for example, be sensors for the analyte other than the sensor whose operating state is being determined. Such sensors that are not similar may, for example, be of a different type (e.g., a flammable gas sensor if the similar sensor is an electrochemical gas sensor).

[0077] Furthermore, sensors for environmental conditions, such as pressure sensors, humidity sensors, altitude sensors, or altimeters, may also be used, or alternatively, to determine the operating state. Data from temperature and / or humidity sensors may be used, for example, to determine an appropriate range of reference for a measured parameter (e.g., the delta MPV described in the representative examples herein). Different setpoints may be set for cold, dry locations where the sensors are located compared to warm, humid locations. Altitude may be related to oxygen concentration, for example, which affects the output of oxygen and flammable gas sensors. At high altitudes, oxygen concentration is lower than at sea level (fewer oxygen molecules per unit volume). Below sea level, for example in underground mines, the environment may be oxygen-rich.

[0078] For example, if the operating status of one or more flammable gas sensors is being tracked under the method herein, an oxygen sensor can be used to determine whether the flammable gas sensors are operating / operating in oxygen-deficient or oxygen-excess conditions over a specific period of time. Such an oxygen sensor may be, for example, an electrochemical gas sensor. Similarly, sensors for inhibitors and / or toxins of flammable gas sensors (e.g., sulfur-containing compounds, halogens, silicon-containing compounds, etc.) may be sensed by, for example, an electrochemical sensor and / or other sensors.

[0079] Under the methods described herein, if the operating status of one or more electrochemical gas sensors is being tracked, a flammable gas sensor or other sensor may be used, for example, to detect interfering gases to the electrochemical gas sensor. Alcohols may be detected, for example, via a flammable gas sensor. For example, a specification such as that disclosed in U.S. Patent No. 10,234,412, whose disclosure is incorporated herein by reference, may be used to detect species of alcohol. Alcohols can affect certain electrochemical gas sensors, such as carbon monoxide or CO sensors. Even a slight increase in the output of a flammable gas sensor may eventually be associated with an abnormal output from an electrochemical gas sensor for a CO sensor, or that such a sensor may go offline. Alkenes may also be detected via a flammable gas sensor. Alkenes are similarly interfering substances for electrochemical gas sensors for CO. Data from one or more flammable gas sensors may be used to determine whether there are alkenes causing a response in one or more CO sensors.

[0080] By analyzing the history or time span of data from one or more gas sensors, pressure sensors, humidity sensors, temperature sensors, etc., it may be determined how such data history may affect the performance of one or more sensors monitored under the methods herein. Location data (e.g., from GPS or other systems) and the locations of one or more monitored sensors within a facility may be correlated with, for example, gas test data, anomalies, alarms, upscaled measurements, downscaled measurements, etc. The determination and / or analysis of non-standard conditions or events may be associated with the output of one or more monitored sensors.

[0081] Various types of gas sensors may include one or more filters to limit or prevent, for example, contact with or exposure to inhibitors, toxins, interferants, etc., of the gas sensing element. Changes in the transport properties of such filters due to exposure to such inhibitors, toxins, interferants, etc., may affect the sensor response. A sensor sensitive to inhibitors, toxins, interferants, etc., of one or more sensors monitored using the methodology herein may be used, for example, in interpreting the output trend of such sensors. Similarly, such a sensor sensitive to inhibitors, toxins, interferants, etc., may be used to monitor or track the operating state of filters for one or more sensors monitored using the methodology herein.

[0082] Figure 7 shows a typical embodiment of a system for collecting, communicating, and analyzing data from one or more sensors, which may be located in a single facility or distributed across multiple facilities. In some embodiments of this specification, facility 200a (e.g., an oil refinery, an offshore drilling rig, a manufacturing facility, an industrial chemical plant, etc.) includes one or more sensors 10a(i) to 10a(vii) as specified, while one or more other facilities represented by facility 200b include one or more other sensors 10b(i) to 10b(vii) as specified. Although seven sensors are shown for each of facilities 200a and 200b, facilities may include fewer or more sensors. Some facilities may include, for example, 100 or more sensors. The operation of the system components of facility 200b (and / or other facilities) with respect to data collection, communication, and / or processing is very similar to that of the components of facility 200a. Therefore, data communication and / or processing in the systems of this specification will be described below primarily in relation to facility 200a.

[0083] As described above, each sensor 10a(i) in this specification includes a communication system (e.g., a transceiver) which may be wired or wireless. Data from sensors 10a(i) to 10a(vii) can be communicated directly to, for example, a remote processing system 500, which will be further described below. Alternatively, data from sensors 10a(i) to 10a(vii) can be transmitted to the remote system 500 via a local system 250a. In some embodiments, data can be communicated from sensors 10a(i) to 10a(vii) to the local system 250a via a local network 220a which includes, for example, a 4 to 20 milliampere transmission system known in the art, an Ethernet-based network, and / or a wireless network. The data can be collected for analysis, for example, and transmitted to the remote system 500 in real time. Data transfer can be continuous or discontinuous / batch. For example, raw or processed sensor data may be transmitted to the remote system 500 by the local system 250a for processing (or further processing) and / or analysis by the remote system 500. The remote system 500 may receive data from several local systems 250a, 250b, etc. (i.e., from several different facilities). The local system 250a may include, for example, a processing system 252a (e.g., including one or more processors or microprocessors), an associated memory system 254a communicating with the processor system 252a, and a communication system 256a communicating with the processor system 252a. Processing / analysis may be distributed, for example, within the sensor processing system, the local system, and the remote system 500 (e.g., when determining upper and lower threshold values ​​for a group). Transmission from sensor 10a(i) to 10a(vii) and / or from local system 250a to remote system 500 is performed via network 400, which may include wired and / or wireless communication protocols (e.g., data via mobile phone transmission protocol, internet transmission protocol, telephone line protocol, etc.).

[0084] The remote system 500 may include, for example, a central processing system or a distributed processing system, which may include, for example, one or more computers, servers, or server systems 510. The computers, servers, or server systems 510 may include, for example, one or more processors or processor systems 512 that are connected to one or more memories or memory systems 514, as is known in computer technology. The memory system 514 may include one or more databases 516 stored therein. Local systems 250a, 250b, etc., may communicate with the communication system or system 520 of the remote system 500 via one or more wired or wireless communication channels 400 (e.g., landline telephones, wireless telephones, broadband internet connections, and / or other communication channels), as described above. Software stored in the memory system 514, or one or more other memory systems connected to the processors 512, may be used to process or analyze data from the local systems 250a, 250b, etc.

[0085] The above description and accompanying drawings illustrate several representative embodiments at present. Naturally, various modifications, additions, and alternative designs will be apparent to those skilled in the art in light of the above teachings, without departing from the scope of this specification as set forth by the following claims, rather than from the above description. All changes and variations that fall within the meaning and scope of equivalence of the claims shall be encompassed within that scope.

Claims

1. A method for operating a gas sensor for a gas analyzer, including a detection component, In the first mode, the sensor is queried by periodically applying an electrical signal to the sensor's detection component, the sensor response to the electrical signal indicating the sensor's sensitivity is measured each time the electrical signal is applied to the detection component, and based on the sensor response determined each time the electrical signal is applied to the detection component, it is determined whether one or more thresholds have been exceeded, and A method comprising entering a second mode different from the first mode in the analysis of a sensor response to a periodically applied electrical signal when one or more thresholds are exceeded.

2. The method according to claim 1, wherein the sensor response to the periodically applied electrical signal in the second mode is analyzed to determine whether the sensor response to the periodically applied electrical signal is stable.

3. The method according to claim 2, further comprising determining the rate of change of the sensor response during the second mode in order to determine whether the sensor response to the periodically applied electrical signal is stable.

4. The method according to claim 2, further comprising changing one or more thresholds after determining that the sensor response to the periodically applied electrical signal has stabilized.

5. The method according to claim 1, wherein the sensor response is determined without applying a test gas to the sensor.

6. The method according to claim 3, wherein at least one of the magnitude and direction of the rate of change of the sensor response is determined.

7. The method according to claim 3, wherein the sensor is an electrochemical gas sensor, and the detection component is the working electrode of the electrochemical gas sensor.

8. The method according to claim 7, wherein the value of the sensor response is determined based on at least one defined parameter of the sensor response.

9. The method according to claim 8, wherein the at least one defined parameter of the sensor response is selected from the group consisting of the maximum current peak value, the area under the current curve, the minimum peak value, the peak-to-peak value, the area under the inversion curve, the baseline value of the sensor response, or one or more functions thereof.

10. The method according to claim 8, wherein the value of the sensor response in each of the periodically applied electronic queries is the change from a value determined at the time of calibration of the sensor for at least one defined parameter of the sensor response measured in each of the periodically applied electronic queries.

11. The method according to claim 2, wherein one or more thresholds of the sensor response are determined by tracking the values ​​of the sensor response over time and determining upper and lower thresholds for a reference behavior relating to the sensor.

12. The method according to claim 2, wherein the one or more thresholds of the sensor response are determined by tracking the sensor response over time for a plurality of similar sensors and determining an upper threshold and a lower threshold for a group of criteria for the operation of the plurality of similar sensors.

13. The method according to claim 12, wherein one or more other thresholds are determined by tracking the sensor response of each of the plurality of similar sensors over time, and determining individual upper and lower thresholds for a reference operation for each of the plurality of similar sensors.

14. The method according to claim 13, wherein each of the plurality of similar sensors enters the second mode based on comparing the sensor response of each of the plurality of similar sensors with the upper threshold and lower threshold of the group, and the individual upper threshold and individual lower threshold of the group.

15. The method according to claim 7, wherein the one or more thresholds of the sensor response are determined by tracking the values ​​of the sensor response over time and determining upper and lower thresholds for a reference operation relating to the sensor.

16. The method according to claim 7, wherein the one or more thresholds of the sensor response are determined by tracking the sensor responses of a plurality of similar sensors over time and determining an upper threshold and a lower threshold for a group of criteria for the operation of the plurality of similar sensors.

17. The method according to claim 16, wherein one or more other thresholds are determined by tracking the sensor response of each of the plurality of similar sensors over time and determining individual upper and lower thresholds for a reference operation for each of the plurality of similar sensors.

18. The method according to claim 17, wherein each of the plurality of similar sensors enters the second mode based on comparing the sensor response of each of the plurality of similar sensors with the upper threshold and lower threshold of the group, and the individual upper threshold and individual lower threshold of the group.

19. The method according to claim 16, wherein each of the plurality of similar sensors has at least one common characteristic other than being a similar sensor.

20. The method according to claim 19, wherein the at least one common characteristic is a geographical area of ​​deployment or a range of manufacturing time.

21. The method according to claim 1, wherein data from the sensor is transmitted to a remote processor system for analysis.

22. The method according to claim 1, wherein data from a second gas sensor for a second gas analyzer different from the aforementioned gas analyzer, or data from a third sensor for environmental conditions, is transmitted to the gas sensor.

23. A sensor comprising a detection component having at least one property that is sensitive to the analyte, and A system comprising a circuit configured to operate with a sensing component in a first mode of querying a sensor by periodically applying an electrical signal to the sensing component, wherein each time an electrical signal is applied to the sensing component, the circuit measures the sensor response to the electrical signal indicating the sensitivity of the sensor, compares the sensor response to one or more thresholds, and the circuit is further configured to determine, based on the comparison of the sensor response to one or more thresholds, whether to enter a second mode different from the first mode in the analysis of the sensor response to the periodically applied electrical signal if one or more thresholds are exceeded.

24. The system according to claim 23, wherein the circuit is configured to analyze the sensor response to the periodically applied electrical signal in the second mode and to determine whether the sensor response to the periodically applied electrical signal is stable.

25. The system according to claim 24, wherein the circuit is further configured to determine the rate of change of the sensor response during the second mode and to determine whether the sensor response to the periodically applied electrical signal is stable.

26. The system according to claim 24, wherein the circuit is further configured to change one or more thresholds after determining that the sensor response to the periodically applied electrical signal has stabilized.

27. The system according to claim 23, wherein the circuit is configured to determine the sensor response without applying a test gas to the sensor.

28. The system according to claim 25, wherein at least one of the magnitude and direction of the rate of change of the sensor response is determined.

29. The system according to claim 25, wherein the sensor is an electrochemical gas sensor, and the detection component is the working electrode of the electrochemical gas sensor.

30. The system according to claim 29, wherein the value of the sensor response is determined based on at least one defined parameter of the sensor response.

31. The system according to claim 30, wherein the at least one defined parameter of the sensor response is selected from the group consisting of the maximum current peak value, the area under the current curve, the minimum peak value, the peak-to-peak value, the area under the inversion curve, the baseline value of the sensor response, or one or more functions thereof.

32. The system according to claim 29, wherein the value of the sensor response in each of the periodically applied electronic queries is the change in the value of at least one defined parameter of the sensor response measured in each of the periodically applied electrical signals from a value determined at the time of calibration of the sensor.

33. The system according to claim 24, wherein one or more thresholds of the sensor response are determined by tracking the value of the sensor response over time and determining upper and lower thresholds for a reference behavior relating to the sensor.

34. The system according to claim 24, wherein the one or more thresholds of the sensor response are determined by tracking the sensor response over time for a plurality of similar sensors and determining an upper threshold and a lower threshold for a group of criteria for the operation of the plurality of similar sensors.

35. The system according to claim 34, wherein each of the plurality of similar sensors includes a communication system that transmits data relating to the sensor response to the periodically applied electrical signal and receives data relating to the upper threshold and lower threshold of the group for a reference operation relating to the plurality of similar sensors.

36. The system according to claim 34, wherein one or more other thresholds are determined by tracking the sensor response of each of the plurality of similar sensors over time and determining individual upper and lower thresholds for a reference operation for each of the plurality of similar sensors.

37. The system according to claim 36, wherein each of the plurality of similar sensors enters the second mode based on comparing the sensor response of each of the plurality of similar sensors with the upper threshold and lower threshold of the group, and the individual upper threshold and individual lower threshold of the group.

38. The system according to claim 29, wherein the one or more thresholds of the sensor response are determined by tracking the values ​​of the sensor response over time and determining upper and lower thresholds for a reference operation relating to the sensor.

39. The system according to claim 29, wherein the one or more thresholds of the sensor response are determined by tracking the sensor responses of a plurality of similar sensors over time and determining an upper threshold and a lower threshold for a group of criteria for the operation of the plurality of similar sensors.

40. The system according to claim 39, wherein one or more other thresholds are determined by tracking the sensor response of each of the plurality of similar sensors over time and determining individual upper and lower thresholds for a reference operation for each of the plurality of similar sensors.

41. The system according to claim 40, wherein each of the plurality of similar sensors transmits data relating to the sensor response to the periodically applied electronic query, and a communication system for receiving data relating to the upper threshold and lower threshold of the group for a reference operation relating to the plurality of sensors.

42. The system according to claim 40, wherein each of the plurality of similar sensors enters the second mode based on comparing the sensor response of each of the plurality of similar sensors with the upper threshold and lower threshold of the group, and the individual upper threshold and individual lower threshold of the group.

43. The system according to claim 40, wherein each of the plurality of similar sensors has at least one common characteristic other than being a similar sensor.

44. The system according to claim 43, wherein the at least one common characteristic is a geographical area of ​​deployment or a range of manufacturing time.

45. The system according to claim 23, wherein data from the sensor is transmitted to a remote processor system for analysis.

46. The system according to claim 23, wherein data from a second gas sensor for a second gas analyzer different from the aforementioned gas analyzer, or data from a third sensor for environmental conditions, is transmitted to the gas sensor.

47. A method for operating a system comprising a plurality of similar gas sensors, wherein each of the plurality of similar gas sensors comprises a detection component, A first mode of the method includes querying each of the plurality of similar gas sensors by periodically applying an electrical signal to the sensing component of the sensor, determining a sensor response to the electrical signal that indicates the sensitivity of each of the plurality of similar gas sensors each time the electrical signal is applied to the sensing component, and analyzing the sensor response of each of the plurality of similar gas sensors to the periodically applied electrical signal based on a reference response of the plurality of similar gas sensors to the periodically applied electrical signal determined over time.

48. The method according to claim 47, further comprising determining whether each of the plurality of similar gas sensors enters a second mode different from the first mode in the analysis of the sensor response to the periodically applied electrical signal, based on a comparison of the sensor response of each of the plurality of similar gas sensors in the first mode with a reference response of the plurality of similar gas sensors.

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