Patent Description:
<CIT> relates to an electrochemical sensor for detecting a predetermined gas.

An aspect of the invention provides a gas sensor for detecting target gas and test gas, comprising: a housing defining an opening to an external environment; a sensing electrode disposed in the housing and configured to generate a test gas signal when the sensing electrode is in contact with a test gas; a membrane disposed in the housing between the sensing electrode and the opening in the housing, wherein the membrane is at least partially exposed to the external environment; a test gas diffusion path defined in the housing for the test gas to travel in the gas sensor and comprising an inlet and an outlet; and a capillary disposed between the sensing electrode and the outlet of the test gas diffusion path, wherein the test gas diffusion path is disposed between the membrane and the capillary, the test gas diffusion path including a first wall and a second wall that define the test gas diffusion path, the first wall defining a first test gas diffusion path opening to expose the test gas to the membrane, the second wall defining a second test gas diffusion path opening to expose the test gas to the capillary and sensing electrode, the first test gas diffusion path opening disposed prior to the second test gas diffusion path opening along the test gas diffusion path in a direction of flow from the inlet of the test gas diffusion path to the outlet of the test gas diffusion path, such that when the test gas travels through the test gas diffusion path from the inlet to the outlet, the test gas comes in contact with the membrane prior to coming in contact with the capillary and then the sensing electrode, wherein a total amount of the test gas signal is higher when the membrane has a high degree of restriction of gas access compared to the total amount of the test gas signal when the membrane has a low degree of restriction of gas access, and wherein a magnitude of the test gas signal indicates a degree of restriction of gas access by the capillary.

In some embodiments, the inlet of the test gas diffusion path is disposed distal to the sensing electrode and the outlet of the test gas diffusion path is disposed proximal to the sensing electrode. In some embodiments, the gas sensor further comprises a test gas electrode configured to generate the test gas at the inlet of the test gas diffusion path.

In some embodiments, the test gas comprises hydrogen, carbon monoxide, or combinations thereof. and wherein the test gas is generated electrochemically by the test gas electrode.

In some embodiments, the test gas electrode is configured to generate the test gas at periodic intervals of time.

In some embodiments, a circuitry of the gas sensor is configured to switch the gas sensor from a diagnostic mode to a normal operating mode when the sensing electrode detects a target gas. In some embodiments, the inlet of the test gas diffusion path is disposed concentrically around the sensing electrode. In some embodiments, the inlet of the test gas diffusion path is disposed at a first end of the housing and the sensing electrode is disposed at a second end of the housing.

Another aspect of the present invention provides a gas sensor system comprising the aforementioned gas sensor and an external test gas generator configured to generate test gas, wherein when the external test gas generator generates test gas, the gas sensor and external test gas generator are operatively coupled such that test gas enters the inlet of the test gas diffusion path of the gas sensor.

Another aspect of the present invention provides a method of using the aforementioned gas sensor, comprising: causing the test gas to travel through a test gas diffusion path disposed in the gas sensor, and determining a degree of restriction of gas access by the membrane in the gas sensor.

In some embodiments, determining the degree of restriction of gas access by the membrane in the gas sensor may include receiving a test gas signal from the sensing electrode and integrating the test gas signal.

In some embodiments, the method may include applying restriction compensation to a target gas signal in response to the degree of restriction of gas access by the membrane.

Some embodiments of the present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the inventions are shown. Indeed, the invention is set out in the appended set of claims and may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements.

As used herein, the terms "data," "content," "digital content," "digital content object," "information," and similar terms may be used interchangeably to refer to data capable of being transmitted, received, and/or stored in accordance with embodiments of the present invention. Thus, use of any such terms should not be taken to limit the scope of the present invention as defined by the appended claims. Further, where a device is described herein to receive data from another device, it will be appreciated that the data may be received directly from the another device or may be received indirectly via one or more intermediary devices, such as, for example, one or more servers, relays, routers, network access points, base stations, hosts, repeaters, and/or the like, sometimes referred to herein as a "network. " Similarly, where a device is described herein to send data to another device, it will be appreciated that the data may be sent directly to the another device or may be sent indirectly via one or more intermediary devices, such as, for example, one or more servers, relays, routers, network access points, base stations, hosts, repeaters, and/or the like.

The term "comprising" means including but not limited to, and should be interpreted in the manner it is typically used in the patent context. Use of broader terms such as comprises, includes, and having should be understood to provide support for narrower terms such as consisting of, consisting essentially of, and comprised substantially of.

The phrases "in one embodiment," "according to one embodiment," and the like generally mean that the particular feature, structure, or characteristic following the phrase may be included in at least one embodiment of the present invention, and may be included in more than one embodiment of the present invention (importantly, such phrases do not necessarily refer to the same embodiment).

The terms "about" or "approximately" or the like, when used with a number, may mean that specific number, or alternatively, a range in proximity to the specific number, as understood by persons of skill in the art field.

As used herein, the term "transmitter" refers to any component that can generate radio waves for communication purposes while a "receiver" is used to generally refer to any component that can receive radio waves and convert the information into useable form. A "transceiver" generally refers to a component that can both generate radio waves and receive radio waves and is thus contemplated when either a transmitter or a receiver is discussed.

Various embodiments of the of the present invention are directed to systems, methods, and devices that are configured to detect the restriction of gas in a gas sensor. In particular, the systems, methods, and devices are configured to detect the restriction of gas access to the sensing electrode of the gas sensor. The restriction of gas access by a membrane or capillary of an electrochemical gas sensor may be detected, compensated for, and flagged for correction without the need to apply an external target gas and without the need for user intervention.

Prior gas sensors required bump testing where a pulse of the target gas is manually or automatically generated and applied to the gas sensor to test the ability of the gas sensor to identify the target gas. For instance, in some cases, an operator breathes on the gas sensor to test the operation of the gas sensor. In some cases, a pulse of target gas may be automatically generated using a bump test station, where an operator is required to physically move the gas sensor to the bump test station for testing. Fixed installations may include built in or piped in gas supply. However, such testing is inconvenient, costly, and potentially hazardous. In some applications, bump testing is required to be performed daily, thereby placing a significant burden on operators of the gas sensor. Other gas sensors may generate target gases externally or internally and then apply the target gas to the gas sensor to measure the performance of the gas sensor electrode. However, these gas sensors are not able to determine whether a blockage has been formed in the gas sensor, much less determine the degree of any blockage in the gas sensor.

Removal of the need to perform bump tests can save a significant amount of money over the lifetime of a gas sensor. Further, identification of partial or complete restriction or blockage of membranes and capillaries in gas sensors allows operators to identify failure modes and correct the failure modes prior to complete blockage (e.g., where partial restriction or blockage is identified). The ability to independently quantify the degree of restriction of the membrane and/or capillary may allow compensation to be applied and may allow the gas sensor to flag, in advance, the need to replace or clean a membrane or capillary. The need to replace the gas sensor itself can also be determined.

Provided herein is a self-contained and autonomous system, method, and device for detecting gas restrictions in gas sensors. The system, method, and device can be used to detect gas restrictions in gas sensors without significantly disturbing normal operations of the sensor.

In some embodiments, a pulse of test gas is electrochemically generated into a void ("test gas diffusion path") disposed between the membrane and sensing electrode of the gas sensor. The resulting transient signal on the sensing electrode is then analyzed. In some embodiments, the test gas is hydrogen, carbon monoxide, or any other suitable gas that can be applied to the gas sensor. The target gas can be various types of gases including oxygen as well as toxic gases such as carbon monoxide, sulphur dioxide, and hydrogen sulfide. The gas sensor may be a <NUM>, <NUM>, or more electrode (or other) amperometric design.

In some embodiments, a test gas is generated within the sensor housing (e.g., H<NUM>, CO, etc. generated by a test gas electrode disposed within the gas sensor housing) and the resulting test gas signal on the sensing electrode may be used to determine the degree of restriction of the capillary and/or membranes. The test gas may be hydrogen produced by electrolysis of water in the electrolyte, or may be carbon monoxide produced electrochemically utilizing the reverse water gas shift reaction (CO<NUM> + H<NUM> → CO + H<NUM>O) (CO2 is usually present and H2 can be generated electrochemically). The test gas is fed into the test gas diffusion path between the capillary and the outer protective membrane. A portion of the test gas reaches the sensing electrode and is detected, while a portion of the test gas escapes through the membrane of the gas sensor. A comparison of the total amount of test gas detected with the amount of test gas generated or applied to the gas sensor provides a measure of the degree of restriction of the membrane. The magnitude of the test gas signal provides a measure of the degree of capillary restriction.

The test gas may be generated as a pulse of known charge (e.g., a known number of moles of test gas generated). The integrated charge on the sensing electrode may measure the fraction of the test gas that has not escaped out of the gas sensor through the membrane. For example, a more restricted membrane may result in a greater fraction of the test gas being detected. To avoid overloading the gas sensor, the test gas pulse may be kept small and short, but sufficient to be detected by the sensing electrode and analyzed.

In some embodiments, the test gas pulse of known charge may be generated by a test gas electrode and fed into the test gas diffusion path between the membrane and the sensing electrode. A capillary is present between the sensing electrode and the test gas diffusion path. A portion of the test gas escapes the gas sensor through the membrane. If the membrane is damaged or missing, then most of the test gas may escape the gas sensor. If the membrane is highly restricted or blocked, then very little test gas may escape the gas sensor leaving most of the test gas to be detected by the sensing electrode.

By having a test gas diffusion path between the membrane and the capillary (and thus between the membrane and the sensing electrode), the membrane may be considerably restricted before the sensing electrode sensitivity is affected. In some embodiments, the disclosed system, method, and device is able to detect restriction of the membrane long before the membrane becomes restricted enough to limit gas sensitivity, thereby providing an advanced warning of failure. In some embodiments, the system, method, and device enables compensation to be applied to the gas sensor to allow for increased restriction by membrane. In some embodiments, such as where the membrane is highly restricted, failure may be flagged. In some embodiments, the system, method, and device may also detect torn or missing membranes. For example, the amount of test gas that reaches the sensing electrode may be much lower than normal, indicating that the membrane is torn or missing.

The system, method, and device can independently test and hence compensate for and/or flag restriction of the membrane and the capillary using a single test. By using a pulse of test gas, a number of parameters can be measured, such as the total integrated charge (which may be the main measure for membrane restriction), the peak current (which may be the main measure for capillary restriction), and rates of rise and decay of the detected test gas pulse, which may also provide information regarding the time dependent movement of the gas.

By keeping the test gas pulse short and small, the risk of overloading the sensing electrode may be reduced and the sensing electrode may recover back to the normal operating mode within a short amount of time, such as less than one second. In some embodiments, the gas sensor can continue to detect target gas undisturbed (e.g., taking <NUM> reading per second) while the diagnostic mode is running.

As shown in <FIG>, the gas sensor may be axially symmetrical. However, in some embodiments, the sensing electrode and the test gas electrode may be in various arrangements without deviating from the present invention. For instance, in <FIG>, the gas sensor includes a test gas electrode on one end of the gas sensor and the sensing electrode on the other end of the gas sensor with the test gas diffusion path disposed between the two electrodes and open to the membrane between the two electrodes.

In some embodiments, the test gas electrode may be disabled when not generating test gas. In some embodiments, after generating a test gas pulse, the test gas electrode may be set to a potential where the test gas electrode may detect the test gas. In such embodiments, there are then two test gas detection transients (e.g., the total charge may still give the degree of membrane restriction, however, with two gas detection transients, more information may be obtained). In such embodiment, less of the test gas may diffuse into the bulk of the electrolyte where such diffusion could cause issues.

In some embodiments, a scavenging electrode in the electrolyte below the test gas electrode may be used. In some embodiments, the test gas electrode and the sensing electrodes may be in the same electrolyte (e.g., operated as a bipotentiostat with common counter and reference electrodes), while in some embodiments, the test gas electrode could be in a separate compartment with separate counter and reference electrodes and optionally a different electrolyte (e.g., an electrolyte specifically designed for test gas generation).

The disclosed systems, methods, and devices may be used in a variety of applications. For instance, the test gas electrode, where test gas is generated, may be used in non-electrochemical sensors such as pellistors.

The electrodes may be screen printed, automatically puddled on a substrate, such as a flexible tape, T-I, or combinations thereof. Various selective deposition techniques may be used, such as direct puddling, screen printing, or puddling onto a temporary support followed by press transfer. Conductors may be used to electrically connect each or several electrodes to circuitry <NUM>. When more than one electrode is used, the electrodes may be of the same material or different materials. In some embodiments, the electrodes comprises one or more materials, such as platinum, iridium, ruthenium, gold, silver, carbon, or combinations thereof. For instance, catalyst materials for either the sensing electrode or test gas electrode may include platinum, iridium, ruthenium, gold, silver, carbon, or mixtures of these. In some embodiments, the sensing electrode may detect both the target gas and the test gas. In some embodiments, the sensing electrode and test gas electrode comprise the same material.

The membrane may comprise any suitable material, such as polytetrafluoroethylene (PTFE), and may include any suitable mesh size. The materials and construction of the membrane may vary based on the intended application of the gas sensor. The gas sensor may be used to detect a single target gas, two target gases, or a plurality of target gases. The gas sensor may also monitor the temperature, pressure, location, and movement of the gas sensor and environment in which the gas sensor is located (e.g., the "external environment").

While one or more electrodes are operating as disclosed herein, one or more other electrodes may be performing different functions, such as being treated electrochemically for remediation purposes. Circuitry <NUM> may switch, activate, or deactivate electrodes, both for sensing a target gas and sensing a test gas. Multiple reference or counter electrodes can be provided. One benefit to the use of multiple electrodes is that there is built in redundancy due to the use of multiple sensing electrodes. Since these can be operated alternatively, any poisoning or degradation processes may occur differently on the different electrodes and hence drift in performance can be detected by comparison of the responses on the various electrodes. <CIT> describes gas sensors and electrodes.

Methods, apparatuses, and systems, of the present invention may be embodied by any of a variety of devices. For example, the method, apparatus, and systems may be embodied by a networked device (e.g., an enterprise platform), such as a server or other network entity, configured to communicate with one or more devices, such as gas sensors. Additionally or alternatively, the system may include fixed computing devices, such as a personal computer or a computer workstation. Still further, example embodiments may be embodied by any of a variety of mobile devices, such as a portable digital assistant (PDA), mobile telephone, smartphone, laptop computer, tablet computer, wearable, or any combination of the aforementioned devices.

In some embodiments, the circuitry <NUM> and/or gas sensory system <NUM> described herein may be embodied in a single self-contained portable or fixed gas sensor. For instance, in some embodiments, all of the functionality and processing described herein may be incorporated into a gas sensor itself as an intelligent sensor module which provides a completely processed digital output to the instrument (e.g., ASICS and embedded processors are sufficiently powerful).

<FIG> shows gas sensor system <NUM> including an example network architecture for a system, which may include one or more devices and sub-systems that are configured to implement some embodiments discussed herein. For example, gas sensor system <NUM> may include server <NUM> and/or client device <NUM>, which can include, for example, the circuitry disclosed in <FIG>, a server, or database, among other things (not shown). The server <NUM> and/or client device <NUM> may include any suitable network server and/or other type of computing device. In some embodiments, the server <NUM> and/or client device <NUM> may receive, determine, and transmit alarms, data, and instructions to gas sensor 400A-400N using data from the gas restriction detection database <NUM>. The gas restriction detection database <NUM> (shown e.g., in <FIG> and <FIG>) may be embodied as a data storage device such as a Network Attached Storage (NAS) device or devices, or as a separate database server or servers. The gas restriction detection database <NUM> includes information accessed and stored by the server <NUM> and/or client device <NUM> to facilitate the operations of the gas sensor system <NUM>. For example, the gas restriction detection database <NUM> may include, without limitation, a plurality of sensing electrode data, telemetry data, application data, test gas data, test gas electrode data, gas sensor data, etc..

Server <NUM> and/or client device <NUM> can communicate with one or more gas sensors 400A-400N via communications network <NUM>. In this regard, communications network <NUM> may include any wired or wireless communication network including, for example, a wired or wireless local area network (LAN), personal area network (PAN), metropolitan area network (MAN), wide area network (WAN), or the like, as well as any hardware, software and/or firmware required to implement it (such as, e.g., network routers, etc.). For example, communications network <NUM> may include a cellular telephone, an <NUM>, <NUM>, <NUM>, and/or WiMax network. Further, the communications network <NUM> may include a public network, such as the Internet, a private network, such as an intranet, or combinations thereof, and may utilize a variety of networking protocols now available or later developed including, but not limited to TCP/IP based networking protocols. For instance, the networking protocol may be customized to suit the needs of the gas restriction detection system.

The server <NUM> and/or client device <NUM> may provide for receiving of electronic data from various sources, including but not necessarily limited to the gas sensors 400A-400N. For example, the server <NUM> and/or client device <NUM> may be operable to receive or transmit sensing electrode data, telemetry data, application data, test gas data, test gas electrode data, gas sensor data provided by the gas sensors 400A-400N.

Gas sensors 400A-400N, server <NUM>, and/or client device <NUM> may each be implemented using a personal computer and/or other networked device, such as a cellular phone, tablet computer, mobile device, inventory management terminal etc. that may be used for any suitable purpose in addition to monitoring the gas sensors. The depiction in <FIG> of "N" devices is merely for illustration purposes. Any number of gas sensors may be included in the gas sensor system <NUM>. In one embodiment, the gas sensors 400A-400N may be configured to view, create, edit, and/or otherwise interact with target gas information, test gas information, and/or telemetry data of the gas sensor, system, and/or environment in which the gas sensor is located, which may be provided by the client device <NUM>, server <NUM>, gas sensors 400A-400N, or other devices in the gas sensor system <NUM>. According to some embodiments, the server <NUM> and/or client device <NUM> may be configured to display the test gas information and/or telemetry data on a display of the server <NUM> and/or client device <NUM> for viewing, creating, editing, and/or otherwise interacting with the data. In some embodiments, an interface of a gas sensor 400A-400N may be different from an interface of a server <NUM> and/or client device <NUM>. The gas sensors 400A-400N may be used in addition to or instead of the server <NUM> and/or client device <NUM>. Gas sensor system <NUM> may also include additional client devices and/or servers, among other things. Additionally or alternatively, the gas sensor 400A-400N may interact with the gas sensor system <NUM> via a web browser. As yet another example, the gas sensor 400A-400N may include various hardware or firmware designed to interface with the gas sensor system <NUM>.

In some embodiments, the gas sensors 400A-400N are electrochemical gas sensors. In some embodiments, the gas sensors 400A-400N may include any computing device as defined above. Electronic data received by the server <NUM> and/or client device <NUM> from the gas sensors 400A-400N may be provided in various forms and via various methods. In some embodiments, the gas sensors 400A-400N, server <NUM>, and client device <NUM> may include mobile devices, wearables, and the like.

In embodiments where the client device <NUM> and/or server <NUM> is a mobile device, such as a smart phone or tablet, the server <NUM> and/or client device <NUM> may execute an "app" to interact with the gas sensor system <NUM>. Such apps are typically designed to execute on mobile devices, such as tablets or smartphones. For example, an app may be provided that executes on mobile device operating systems such as iOS®, Android®, or Windows®. These platforms typically provide frameworks that allow apps to communicate with one another and with particular hardware and software components of mobile devices. For example, the mobile operating systems named above each provide frameworks for interacting with location services circuitry, wired and wireless network interfaces, user contacts, and other applications. Communication with hardware and software modules executing outside of the app is typically provided via application programming interfaces (APIs) provided by the mobile device operating system.

In some embodiments of an exemplary gas sensor system <NUM>, information may be sent from a gas sensor 400A-400N to the server <NUM> and/or client device <NUM>. In various implementations, the information may be sent to the gas sensor system <NUM> over communications network <NUM> directly by a gas sensor 400A-400N, the information may be sent to the gas sensor system <NUM> via an intermediary such as a another client device, server, and/or the like. For example, the gas sensor 400A-400N may communicate with a desktop, a laptop, a tablet, a smartphone, and/or the like that is executing a client application to interact with the gas sensor system <NUM>. In one implementation, the information may include data such as sensing electrode data, telemetry data, application data, test gas data, test gas electrode data, gas sensor data, and/or the like.

The gas sensor system <NUM> may comprise at least one server <NUM> and/or client device <NUM> that may create a storage data entry based upon the received information to facilitate indexing and storage in a gas restriction detection database <NUM>, as will be described further below. In one implementation, the storage data entry may include data such as sensing electrode data, telemetry data, application data, test gas data, test gas electrode data, gas sensor data, and/or the like.

In one implementation, the sensing electrode data, telemetry data, application data, test gas data, test gas electrode data, gas sensor data, and/or the like may be parsed (e.g., using PHP commands) to determine information regarding the gas sensor, specifically the electrodes, membrane(s), capillary, test gas, external environment in which the gas sensor is located, etc..

<FIG> shows a schematic block diagram of circuitry <NUM>, some or all of which may be included in, for example, server <NUM>, client device <NUM>, and/or gas sensors 400A-400N. Any of the aforementioned server <NUM>, client device <NUM>, and/or gas sensors 400A-400N may include one or more components of circuitry <NUM> and may be configured to, either independently or jointly with other devices in the communications network <NUM> perform the functions of the circuitry <NUM> described herein. As illustrated in <FIG>, in accordance with some example embodiments, circuitry <NUM> can includes various means, such as processor <NUM>, memory <NUM>, communications module <NUM>, and/or input/output module <NUM>. In some embodiments, gas restriction detection database <NUM> may also or instead be included. As referred to herein, "module" includes hardware, software and/or firmware configured to perform one or more particular functions. In this regard, the means of circuitry <NUM> as described herein may be embodied as, for example, circuitry, hardware elements (e.g., a suitably programmed processor, combinational logic circuit, and/or the like), a computer program product comprising computer-readable program instructions stored on a non-transitory computer-readable medium (e.g., memory <NUM>) that is executable by a suitably configured processing device (e.g., processor <NUM>), or some combination thereof.

Processor <NUM> may, for example, be embodied as various means including one or more microprocessors with accompanying digital signal processor(s), one or more processor(s) without an accompanying digital signal processor, one or more coprocessors, one or more multi-core processors, one or more controllers, processing circuitry, one or more computers, various other processing elements including integrated circuits such as, for example, an ASIC (application specific integrated circuit) or FPGA (field programmable gate array), or some combination thereof. Accordingly, although illustrated in <FIG> as a single processor, in some embodiments processor <NUM> comprises a plurality of processors. The plurality of processors may be embodied on a single server <NUM>, client device <NUM>, and/or gas sensor 400A-400N or may be distributed across a plurality of such devices collectively configured to function as circuitry <NUM>. The plurality of processors may be in operative communication with each other and may be collectively configured to perform one or more functionalities of circuitry <NUM> as described herein. In an example embodiment, processor <NUM> is configured to execute instructions stored in memory <NUM> or otherwise accessible to processor <NUM>. These instructions, when executed by processor <NUM>, may cause circuitry <NUM> to perform one or more of the functionalities of circuitry <NUM> as described herein.

Whether configured by hardware, firmware/software methods, or by a combination thereof, processor <NUM> may comprise an entity capable of performing operations according to embodiments of the present invention while configured accordingly. Thus, for example, when processor <NUM> is embodied as an ASIC, FPGA or the like, processor <NUM> may comprise specifically configured hardware for conducting one or more operations described herein. Alternatively, as another example, when processor <NUM> is embodied as an executor of instructions, such as may be stored in memory <NUM>, the instructions may specifically configure processor <NUM> to perform one or more algorithms and operations described herein, such as those discussed in connection with <FIG>.

Memory <NUM> may comprise, for example, volatile memory, non-volatile memory, or some combination thereof. Although illustrated in <FIG> as a single memory, memory <NUM> may comprise a plurality of memory components. The plurality of memory components may be embodied on a single server <NUM>, client device <NUM>, and/or gas sensor 400A-400N or distributed across a plurality of such devices. In various embodiments, memory <NUM> may comprise, for example, a hard disk, random access memory, cache memory, flash memory, a compact disc read only memory (CD-ROM), digital versatile disc read only memory (DVD-ROM), an optical disc, circuitry configured to store information, or some combination thereof. Memory <NUM> may be configured to store information, data (including data discussed with regards to gas restriction detection database <NUM>), applications, instructions, or the like for enabling circuitry <NUM> to carry out various functions in accordance with example embodiments of the present invention. For example, in at least some embodiments, memory <NUM> is configured to buffer input data for processing by processor <NUM>. Additionally or alternatively, in at least some embodiments, memory <NUM> is configured to store program instructions for execution by processor <NUM>. Memory <NUM> may store information in the form of static and/or dynamic information. This stored information may be stored and/or used by circuitry <NUM> during the course of performing its functionalities.

Communications module <NUM> may be embodied as any device or means embodied in circuitry, hardware, a computer program product comprising computer readable program instructions stored on a computer readable medium (e.g., memory <NUM>) and executed by a processing device (e.g., processor <NUM>), or a combination thereof that is configured to receive and/or transmit data from/to another device and/or network, such as, for example, a second circuitry <NUM> and/or the like. In some embodiments, communications module <NUM> (like other components discussed herein) can be at least partially embodied as or otherwise controlled by processor <NUM>. In this regard, communications module <NUM> may be in communication with processor <NUM>, such as via a bus. Communications module <NUM> may include, for example, an antenna, a transmitter, a receiver, a transceiver, network interface card and/or supporting hardware and/or firmware/software for enabling communications with another device of the gas sensor system <NUM>. Communications module <NUM> may be configured to receive and/or transmit any data that may be stored by memory <NUM> using any protocol that may be used for communications between devices of the gas sensor system <NUM>. Communications module <NUM> may additionally or alternatively be in communication with the memory <NUM>, input/output module <NUM> and/or any other component of circuitry <NUM>, such as via a bus.

Circuitry <NUM> may include input/output module <NUM> in some embodiments. Input/output module <NUM> may be in communication with processor <NUM> to receive an indication of a user input and/or to provide an audible, visual, mechanical, or other output to a user. As such, input/output module <NUM> may include support, for example, for a keyboard, a mouse, a joystick, a display, a touch screen display, a microphone, a speaker, a RFID reader, barcode reader, biometric scanner, and/or other input/output mechanisms. In embodiments wherein circuitry <NUM> is embodied as a server or database, aspects of input/output module <NUM> may be reduced as compared to embodiments where circuitry <NUM> is implemented as an end-user machine or other type of device designed for complex user interactions. In some embodiments (like other components discussed herein), input/output module <NUM> may even be eliminated from circuitry <NUM>. Alternatively, such as in embodiments wherein circuitry <NUM> is embodied as a server or database, at least some aspects of input/output module <NUM> may be embodied on an apparatus used by a user that is in communication with circuitry <NUM>. Input/output module <NUM> may be in communication with the memory <NUM>, communications module <NUM>, and/or any other component(s), such as via a bus. One or more than one input/output module and/or other component can be included in circuitry <NUM>.

Gas restriction detection database <NUM> and gas restriction detection system <NUM> may also or instead be included and configured to perform the functionality discussed herein related to storing, generating, and/or editing data. In some embodiments, some or all of the functionality of storing, generating, and/or editing data may be performed by processor <NUM>. In this regard, the example processes and algorithms discussed herein can be performed by at least one processor <NUM>, gas restriction detection database <NUM>, and/or gas restriction detection system <NUM>. For example, non-transitory computer readable media can be configured to store firmware, one or more application programs, and/or other software, which include instructions and other computer-readable program code portions that can be executed to control each processor (e.g., processor <NUM>, gas restriction detection database <NUM>, and gas restriction detection system <NUM>) of the components of circuitry <NUM> to implement various operations, including the examples shown above. As such, a series of computer-readable program code portions are embodied in one or more computer program goods and can be used, with a computing device, server, and/or other programmable apparatus, to produce machine-implemented processes.

In some embodiments, a gas restriction detection database <NUM> may be provided that includes sensing electrode data <NUM>, telemetry data <NUM>, application data <NUM>, test gas data <NUM>, test gas electrode data <NUM>, gas sensor data <NUM>, and/or analytical engine data <NUM>. Sensing electrode data <NUM> may include various information, such as type of electrode, expected life of electrode, date of first use of electrode, relative location of electrode in gas sensor 400A-400N, and any other information concerning the sensing electrode. Telemetry data <NUM> may include various information, such as measurements of temperature, pressure, motion, and the like, which may be measured periodically, at certain dates, or on command. Application data <NUM> may include various information specific to the application in which the gas sensor 400A-400N is used, such as typical or expected telemetry data, gas sensor data, location data, or other data related to the application in which the gas sensor 400A-400N is used. Test gas data <NUM> may include various information, such as type of gas(es) used as the test gas, amount of generated test gas, test gas pulse duration, diagnostic intervals (that is, period of time between diagnostic testing), and other data related to the test gas. Test gas electrode data <NUM> may include various information, such as type of electrode, expected life of electrode, date of first use of electrode, relative location of electrode in gas sensor400A-400N, and any other information concerning the test gas electrode. Gas sensor data <NUM> may include various information, such as make/model/serial number of sensor, type of sensor, expected life of sensor, date of first use of sensor, history of maintenance of sensor, expected date(s) of maintenance of sensor, relative location of sensor in environment, limits on gas sensor readings, and any other information concerning the gas sensor 400A-400N and use of the gas sensor 400A-400N. Additionally or alternatively, the gas restriction detection database <NUM> may include analytical engine data <NUM> which provides any additional information needed by the processor <NUM> in storing, analyzing, generating, and editing data.

Gas restriction detection system <NUM> can be configured to analyze multiple sets of data, such as the data in the gas restriction detection database <NUM>. In this way, gas restriction detection system <NUM> may support multiple algorithms, including those discussed below with respect to sensing electrode data <NUM>, telemetry data <NUM>, application data <NUM>, test gas data <NUM>, test gas electrode data <NUM>, gas sensor data <NUM>, and/or analytical engine data <NUM>, so that the selected algorithm may be chosen at runtime. Further, the present configuration can enable flexibility in terms of configuring additional contexts.

In some embodiments, with reference to <FIG>, the gas restriction detection system <NUM> may include a context determination module <NUM>, an analytical engine <NUM>, and communications interface <NUM>, all of which may be in communication with the gas restriction detection database <NUM>. The gas restriction detection system <NUM> may receive one or more signals (e.g., test gas signals, target gas signals, interrogation signals, response signals, instructions, etc.) that may contain information such as sensing electrode data <NUM>, telemetry data <NUM>, application data <NUM>, test gas data <NUM>, test gas electrode data <NUM>, gas sensor data <NUM>, etc. and may generate the appropriate signals that may contain information such as sensing electrode data <NUM>, telemetry data <NUM>, application data <NUM>, test gas data <NUM>, test gas electrode data <NUM>, gas sensor data <NUM>, etc. in response. The gas restriction detection system <NUM> may use any of the algorithms or processes disclosed herein for receiving one or more signals (e.g., test gas signals, target gas signals, interrogation signals, response signals, instructions, etc.) that may contain information such as sensing electrode data <NUM>, telemetry data <NUM>, application data <NUM>, test gas data <NUM>, test gas electrode data <NUM>, gas sensor data <NUM>, etc. and may generate the appropriate signals that may contain information such as sensing electrode data <NUM>, telemetry data <NUM>, application data <NUM>, test gas data <NUM>, test gas electrode data <NUM>, gas sensor data <NUM>, etc. in response. In some other embodiments, such as when the circuitry <NUM> is embodied in a server <NUM>, client device <NUM>, and/or gas sensors 400A-400N, the gas restriction detection system <NUM> may be located in another circuitry <NUM> or another device, such as another server <NUM>, client device <NUM>, gas sensors 400A-400N, and/or other client device.

The gas restriction detection system <NUM> can be configured to access data corresponding to multiple signals (e.g., interrogation signals, response signals, etc.) that may contain information such as sensing electrode data <NUM>, telemetry data <NUM>, application data <NUM>, test gas data <NUM>, test gas electrode data <NUM>, gas sensor data <NUM>, etc. and may generate the appropriate signals that may contain information such as sensing electrode data <NUM>, telemetry data <NUM>, application data <NUM>, test gas data <NUM>, test gas electrode data <NUM>, gas sensor data <NUM>, etc. in response.

The system may receive a plurality of inputs <NUM>, <NUM> from the circuitry <NUM> and process the inputs within the gas restriction detection system <NUM> to produce an output <NUM>, which may include signals containing appropriate information in response. In some embodiments, the gas restriction detection system <NUM> may execute context determination using the context determination module <NUM>, process the data in an analytical engine <NUM>, and output the results via a communications interface <NUM>. Each of these steps may pull data from a plurality of sources including the gas restriction detection database <NUM>.

When inputs <NUM>, <NUM> are received by the gas restriction detection system <NUM>, a context determination using the context determination module <NUM> may be made. A context determination includes such information as application data, what gas sensor 400A-400N initiated receipt of the input, what type of input was provided (e.g., were test gas signals, target gas signals, interrogation signals, response signals, instructions, etc. received) and under what circumstances was receipt of the input initiated (e.g., where is the gas sensor 400A-400N located, when was the input received, what signal or receipt of information preceded the input, etc.). This information may give context to the gas restriction detection system <NUM> analysis to determine the output. For example, the context determination module <NUM> may inform the gas restriction detection system <NUM> as to the signal and/or information to output.

The gas restriction detection system <NUM> may then compute the output using the analytical engine <NUM>. The analytical engine <NUM> draws information about the applicable signal, gas sensor 400A-400N, etc. from the gas restriction detection database <NUM> and then, in light of the context determination module's <NUM> determination, computes an output, which varies based on the input. The communications interface <NUM> then outputs <NUM> the output to the circuitry <NUM> for storing, displaying on an appropriate interface, transmitting to other devices or server(s), or otherwise using for subsequent action. For instance, the context determination module <NUM> may determine that a test gas signal was received. Based on this information as well as the applicable gas sensor data, telemetry data, sensing electrode data, application data, test gas data, test gas electrode data, etc., the analytical engine <NUM> may determine an appropriate output, such as displaying an alarm that the membrane or capillary associated with the gas sensor 400A-400N associated with the test gas signal is in need of maintenance. The analytical engine <NUM> may receive a target gas signal. Based on this information as well as the applicable gas sensor data, telemetry data, sensing electrode data, application data, test gas data, test gas electrode data, etc., the analytical engine <NUM> may determine that gas sensor 400A-400N should be switched from diagnostic mode to normal operating mode where target gas is monitored. The gas sensor 400A-400N may then have the generation of test gas disabled allowing for monitoring of the target gas. Based on the applicable gas sensor data, telemetry data, sensing electrode data, application data, test gas data, test gas electrode data, etc., the analytical engine <NUM> may determine that a certain period of time has passed since the last diagnostic test. Circuitry <NUM> may then cause test gas to flow through the test gas diffusion path in the appropriate gas sensor 400A-400N.

As will be appreciated, any such computer program instructions and/or other type of code may be loaded onto a computer, processor or other programmable apparatus's circuitry to produce a machine, such that the computer, processor other programmable circuitry that execute the code on the machine create the means for implementing various functions, including those described herein.

It is also noted that all or some of the information discussed herein can be based on data that is received, generated, and/or maintained by one or more components of a local or networked system and/or circuitry <NUM>. In some embodiments, one or more external systems (such as a remote cloud computing and/or data storage system) may also be leveraged to provide at least some of the functionality discussed herein.

As described above and as will be appreciated based on this disclosure, embodiments of the present invention may be configured as methods, personal computers, servers, mobile devices, backend network devices, and the like. Accordingly, embodiments may comprise various means including entirely of hardware or any combination of software and hardware. Furthermore, embodiments may take the form of a computer program product on at least one non-transitory computer-readable storage medium having computer-readable program instructions (e.g., computer software) embodied in the storage medium. Any suitable computer-readable storage medium may be utilized including non-transitory hard disks, CD-ROMs, flash memory, optical storage devices, or magnetic storage devices.

Embodiments of the present invention have been described above with reference to block diagrams and flowchart illustrations of methods, apparatuses, systems and computer program goods. It will be understood that each block of the circuit diagrams and process flowcharts, and combinations of blocks in the circuit diagrams and process flowcharts, respectively, can be implemented by various means including computer program instructions. These computer program instructions may be loaded onto a general purpose computer, special purpose computer, or other programmable data processing apparatus, such as processor <NUM>, gas restriction detection database <NUM>, and/or gas restriction detection system <NUM> discussed above with reference to <FIG>, to produce a machine, such that the computer program product includes the instructions which execute on the computer or other programmable data processing apparatus create a means for implementing the functions specified in the flowchart block or blocks.

These computer program instructions may also be stored in a computer-readable storage device (e.g., memory <NUM>) that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable storage device produce an article of manufacture including computer-readable instructions for implementing the function discussed herein. The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions that execute on the computer or other programmable apparatus provide steps for implementing the functions discussed herein.

Accordingly, blocks of the block diagrams and flowchart illustrations support combinations of means for performing the specified functions, combinations of steps for performing the specified functions and program instruction means for performing the specified functions. It will also be understood that each block of the circuit diagrams and process flowcharts, and combinations of blocks in the circuit diagrams and process flowcharts, can be implemented by special purpose hardware-based computer systems that perform the specified functions or steps, or combinations of special purpose hardware and computer instructions.

<FIG> discuss gas sensor <NUM> which may be any one or more of gas sensors 400A-400N of gas sensor system <NUM>.

<FIG> illustrates an example gas sensor in accordance with some embodiments of the present invention. In particular, <FIG> illustrates a cross-section of a gas sensor <NUM> including a housing <NUM> including housing wall <NUM> that defines an opening <NUM> in the housing <NUM> to the external environment <NUM>. The housing <NUM> also includes a second housing wall <NUM>. The gas sensor <NUM> includes a sensing electrode <NUM>, a capillary <NUM>, a membrane <NUM>, and a test gas diffusion path <NUM>. The test gas diffusion path <NUM> has an inlet <NUM> and an outlet <NUM>. The test gas enters the test gas diffusion path <NUM> at the inlet <NUM> and exits the test gas diffusion path at the outlet <NUM>. In the embodiment illustrated in <FIG>, following the outlet <NUM>, the test gas enters the capillary <NUM> and then comes in contact with the sensing electrode <NUM>.

In the embodiment illustrated in <FIG>, the test gas diffusion path <NUM> includes a first wall <NUM> and a second wall <NUM> defining the test gas diffusion path <NUM> for the test gas to travel through the gas sensor <NUM>. The first wall <NUM> and the second wall <NUM> may each have an inner surface <NUM> and <NUM>, respectively and may define a first test gas diffusion path opening <NUM> that exposes the test gas to the membrane <NUM> and a second test gas diffusion path opening <NUM> that exposes the test gas to the capillary <NUM> and sensing electrode <NUM>. For instance, in the embodiment illustrated in <FIG>, the test gas diffusion path <NUM> includes a first wall <NUM> that defines a first test gas diffusion path opening <NUM> that exposes the test gas traveling through the test gas diffusion path <NUM> to the membrane <NUM>. The second wall <NUM> defines a second test gas diffusion path opening <NUM> that exposes the test gas traveling through the test gas diffusion path <NUM> to the capillary <NUM>. As shown in <FIG>, the test gas diffusion path <NUM> is defined by two walls, however, additional walls may be present, such as a third and fourth wall, without deviating from the present invention. Also, as shown in <FIG>, the outlet <NUM> of the test gas diffusion path <NUM> is also the second test gas diffusion path opening <NUM>.

The sensing electrode <NUM> may include various materials suitable for sensing a target gas as well as a test gas, which may be the same or different from the target gas. The sensing electrode <NUM> may have a first surface <NUM> and a second surface <NUM>. In the embodiment illustrated in <FIG>, the first surface <NUM> is proximal to the capillary <NUM> and the second surface <NUM> is distal to the capillary <NUM>. The capillary <NUM> includes a first end <NUM> and a second end <NUM>. The first end <NUM> of the capillary <NUM> is exposed to the test gas by way of the second test gas diffusion path opening <NUM> of the second wall <NUM> of the test gas diffusion path <NUM>. The second end <NUM> of the capillary <NUM> is adjacent to the sensing electrode <NUM>.

The membrane <NUM> of the gas sensor <NUM> includes a first surface <NUM> and a second surface <NUM>. The second surface <NUM> of the membrane <NUM> is exposed to the external environment <NUM> while the first surface <NUM> is exposed to the test gas by way of the first test gas diffusion path opening <NUM> of the first wall <NUM> of the test gas diffusion path <NUM>.

As shown in <FIG>, the first test gas diffusion path opening <NUM> is disposed prior to the second test gas diffusion path opening <NUM> along the test gas diffusion path <NUM> in the direction of flow from the inlet <NUM> of the test gas diffusion path <NUM> to the outlet <NUM> of the test gas diffusion path <NUM>. As test gas travels through the test gas diffusion path <NUM>, the test gas comes in contact with the membrane <NUM>, particularly the first surface <NUM> of the membrane <NUM>, then the capillary <NUM>, and then the sensing electrode <NUM>. If the membrane <NUM> is clean, that is, does not include any blockage in the pores of the membrane, then some of the test gas would travel through the membrane <NUM> to the external environment <NUM>. Some test gas may travel to the capillary <NUM> and the sensing electrode <NUM>. If the membrane <NUM> is damaged or missing, most of the test gas may be released to the external environment <NUM> and the sensing electrode <NUM> may detect a minor amount of test gas if any. If the membrane <NUM> includes blockage, such as dirt or debris, the test gas will be prevented from traveling through the membrane <NUM> and instead proceed on to the capillary <NUM> and then the sensing electrode <NUM>. If the capillary <NUM> is clean, the test gas will travel quickly to the sensing electrode <NUM>. If the capillary <NUM> is blocked, the test gas will travel as a slower pace to the sensing electrode <NUM>. Accordingly, the test gas signal produced by the sensing electrode <NUM> can be used to determine the degree of restriction of the membrane <NUM> and the capillary <NUM> due to the test gas diffusion path <NUM>. The total amount of test gas detected at the sensing electrode <NUM> may provide the degree of restriction of the membrane <NUM> and the magnitude of the test gas signal produced at the sensing electrode <NUM> may provide the degree of restriction of the capillary <NUM>. Accordingly, the status of the gas sensor <NUM> can be monitored.

Test gas may be caused to travel through the test gas diffusion path <NUM> at various intervals, such as about every <NUM> minutes, <NUM> minutes, <NUM> minutes, <NUM> minutes, <NUM> minutes, <NUM> hour, <NUM> hours, <NUM> hours, <NUM> hours, <NUM> hours, <NUM> hours, <NUM> hours, <NUM> hours, <NUM> hours, <NUM> hours, <NUM> hours, <NUM> hours, <NUM> hours, <NUM> hours, <NUM> hours <NUM> hours, <NUM> hours, <NUM> hours, <NUM> hours, <NUM> hours, <NUM> hours, <NUM> hours, <NUM> hours, <NUM> hours, <NUM> hours, <NUM> hours, <NUM> hours, etc. In some embodiments, the test gas may be caused to travel through the test gas diffusion path <NUM> as needed or on demand. That is, an operator may determine when the diagnostic test is needed and cause the test gas to travel through the test gas diffusion path <NUM>.

With the disclosed test gas diffusion path <NUM> and diagnostic mode, the condition of the membrane <NUM> and the capillary <NUM> may be monitored. Early detection of blockage or cuts/tears in the membrane <NUM> may be obtained as well as early detection of blockage of the capillary <NUM>. Accordingly, the gas sensor <NUM> may receive the appropriate maintenance. The life of the gas sensor <NUM> may be extended with such appropriate maintenance.

As shown in the embodiment illustrated in <FIG>, as the test gas enters the test gas diffusion path <NUM> and moves through the test gas diffusion path <NUM>, the test gas comes in contact with the membrane <NUM>. In the embodiment illustrated in <FIG>, the membrane <NUM> covers the test gas diffusion path <NUM> and the sensing electrode <NUM> from the external environment <NUM>.

In the embodiments illustrated in <FIG>, test gas enters the inlet <NUM> of the test gas diffusion path <NUM>. Test gas may be generated by the gas sensor <NUM> and then enter the test gas diffusion path <NUM> at the inlet <NUM> or may be applied to the gas sensor <NUM> from an external source and enter the test gas diffusion path <NUM> at the inlet <NUM>. For instance, <FIG> illustrates a test gas electrode <NUM> that may be integrated into the gas sensor <NUM> or may be an external test gas generator operatively coupled to the gas sensor <NUM> when test gas is needed or desired. For instance, the test gas electrode <NUM> may be disposed within the housing <NUM> or may be disposed in an external housing that can then be connected to the gas sensor <NUM> to allow the test gas to enter the inlet <NUM> of the test gas diffusion path <NUM>. The test gas electrode <NUM> may include the same or different materials and dimensions as the sensing electrode <NUM>. The same or different electrolyte may be used with the sensing electrode <NUM> and the test gas electrode <NUM> to generate test gas.

In some embodiments, the same electrode (e.g., sensing electrode <NUM> or test gas electrode <NUM>) may be used to generate the test gas and then detect test gas. In such embodiments, the electrode (e.g., sensing electrode <NUM> or test gas electrode <NUM>) may require time to settle since there may be a large current transient when the potential is changed. In addition, in such embodiments, there may be more of a risk of test gas getting into the bulk solution and causing slow recovery.

<FIG> illustrates the flow of test gas in a gas sensor in accordance with some embodiments of the present invention. In particular, <FIG> illustrates gas sensor <NUM> including membrane <NUM>, capillary <NUM>, test gas diffusion path <NUM>, and sensing electrode <NUM>, such as those described in accordance with <FIG>. The flow of test gas is shown by arrows <NUM>, <NUM>, and <NUM>. At the inlet <NUM> of the test gas diffusion path <NUM>, test gas enters <NUM> the test gas diffusion path <NUM>. Test gas then proceeds through the test gas diffusion path <NUM> and is exposed to the membrane <NUM>. Test gas exits <NUM> the gas sensor <NUM> through the membrane <NUM> if able to. That is, if the membrane <NUM> is not sufficiently blocked, then test gas exits <NUM> through the membrane <NUM>. The remainder test gas <NUM> enters the capillary <NUM> and flows to the sensing electrode <NUM>, where the remainder test gas <NUM> is detected and analyzed (e.g., by circuitry <NUM>).

As in <FIG>, the gas sensor <NUM> shown in the embodiment illustrated in <FIG> is concentric with the sensing electrode <NUM> disposed in the middle of the gas sensor <NUM> and the test gas diffusion path <NUM> disposed around the sensing electrode <NUM>. The membrane <NUM> is disposed above the capillary <NUM> and sensing electrode <NUM>. The gas sensor <NUM> is axially symmetrical. However, various geometries and configurations are available without deviating from the present invention.

For instance, <FIG> illustrates an exemplary gas sensor <NUM> in accordance with some embodiments of the present invention. In the embodiment illustrated in <FIG>, the gas sensor <NUM> may include a first end <NUM> and a second end <NUM> where the inlet <NUM> of the test gas diffusion path <NUM> may be disposed at the first end of the gas sensor <NUM> and the sensing electrode <NUM> may be disposed at the second end of the gas sensor <NUM>. The membrane <NUM> and capillary <NUM> may be disposed between the first end <NUM> and the second end <NUM> of the gas sensor <NUM> (that is, disposed between the sensing electrode <NUM> and the inlet <NUM> of the test gas diffusion path <NUM>. Various configurations of the gas sensor <NUM> and its components may be available without deviating from the present invention.

<FIG> illustrates simulation results for a diagnostic mode of a gas sensor in accordance with some embodiments of the present invention. In particular, <FIG> illustrates simulation results for a test gas signal detected on the sensing electrode <NUM> following gas pulse generation for a range of membrane <NUM> porosities. The porosity is represented by "p" where a porosity of <NUM> is equivalent to the membrane <NUM> effectively not being present (e.g., the membrane is missing) and thus, the test gas escapes through the opening <NUM>. The membrane <NUM> has the same diffusion coefficient as air. A porosity of zero is equivalent to a completely blocked membrane <NUM> such that all of the test gas flows to the sensing electrode <NUM>.

<FIG> illustrates an expanded scale version of the simulation results shown in <FIG>. As shown in <FIG> (and <FIG>), when the membrane <NUM> has a high porosity (e.g., p is <NUM>, <NUM>, or <NUM>), the sensing electrode <NUM> produces a test gas signal that is relatively small and decays rapidly compared to the test gas signal produced when the membrane has the lowest porosity (e.g., p is zero, <NUM>, or <NUM>). Most of the test gas is lost to the external environment <NUM> through the membrane <NUM> when the porosity is high. When the membrane <NUM> has a low porosity (e.g., p is zero, <NUM>, or <NUM>), the sensing electrode <NUM> produces a test gas signal that is larger and has a longer decay compared to the test gas signal produced when the when the membrane has the highest porosity (e.g., p is <NUM>, <NUM>, or <NUM>). Most of the test gas travels to the sensing electrode when the membrane <NUM> has a low porosity.

<FIG> illustrates simulation results for a diagnostic mode of a gas sensor in accordance with some embodiments of the present invention. <FIG> illustrates simulation results for a test gas signal detected on the sensing electrode <NUM> following gas pulse generation for a range of membrane <NUM> porosities. Again, the porosity is represented by "p" where a porosity of <NUM> is equivalent to the membrane <NUM> effectively not being present and the porosity of zero equivalent to the membrane <NUM> being completely blocked.

In particular, <FIG> illustrates the integrated charge detected by the sensing electrode <NUM> for various porosities. The test gas is a pulse of known charge. Thus, if no test gas is lost through the membrane <NUM> (e.g., the membrane <NUM> is completely blocked), then <NUM>% of the test gas should be detected on the sensing electrode <NUM> when the charge is integrated. If all of the test gas is lost through the membrane <NUM>, then the sensing electrode <NUM> detects no test gas. The integrated charge decreases as the membrane <NUM> is less restrictive (e.g., higher porosity).

<FIG> illustrates a gas sensor during a normal operating mode in accordance with embodiments of the present invention. In particular, during normal operating mode, air <NUM> travels from the external environment <NUM> through the membrane <NUM> into the gas sensor <NUM>. The air <NUM> then travels through the capillary <NUM> to the sensing electrode <NUM> where the sensing electrode <NUM> detects the presence of target gas. As explained above, in some embodiments, test gas may be generated in the gas sensor <NUM>. During normal operating modes, the test gas generation may be disabled such that test gas may not interfere with the sensing electrode <NUM> detecting target gas from the external environment <NUM>. In some embodiments, test gas may be applied from external sources to the gas sensor <NUM>. During normal operating modes, the test gas may be prevented from traveling through the test gas diffusion path <NUM> such that test gas may not interfere with the sensing electrode <NUM> detecting target gas from the external environment <NUM>. Such prevention may occur by disabling a connection to the external source, physically blocking the test gas diffusion path <NUM>, or other methods of preventing test gas from traveling through the test gas diffusion path <NUM>.

In some embodiments, once target gas is detected by the sensing electrode <NUM>, the gas sensor <NUM> may be switched from diagnostic mode to normal operating mode. For instance, while a gas sensor <NUM> is under diagnostic mode (e.g., causing test gas to travel through the test gas diffusion path <NUM>), once the sensing electrode <NUM> detects target gas (e.g., carbon monoxide), circuitry <NUM> may disable the diagnostic mode (e.g., disable the test gas from traveling through the test gas diffusion path <NUM>) so that the gas sensor <NUM> can be operated in the normal operating mode allowing for detection of the target gas. As the pulse of test gas that is used during the diagnostic mode is relatively small and short, switching from diagnostic mode to normal operating mode is generally quick and the gas sensor <NUM> can recover to normal operating mode within a short amount of time (e.g., seconds or less). For instance, test gas pulses can be <NUM> second long such that the gas sensor <NUM> can recover to normal operating mode in less than a second.

In some embodiments, when the target gas is detected by the sensing electrode <NUM> or when the gas sensor <NUM> is already operating in the normal operating mode, the test gas electrode <NUM> may be configured to detect the target gas instead of producing test gas. For instance, the test gas electrode <NUM> may be set to a potential where the test gas electrode <NUM> detects target gas and/or test gas.

Test gas pulses are generally as quick as possible and insert the smallest amount of test gas possible into the test gas diffusion path <NUM>. The test gas pulse should be sufficient to accurately detect test gas on the sensing electrode <NUM> when the membrane <NUM> is not completely blocked and sufficient for analysis of the test gas signal generated by the sensing electrode <NUM>. In some embodiments, the same electrolyte is used for the sensing electrode <NUM> as the test gas generating electrode <NUM>. Thus, the test gas pulse should be relatively small to prevent significant reduction in the electrolyte.

<FIG> illustrates simulation results of normal operating modes in accordance with some embodiments of the present invention. In particular, <FIG> illustrates simulation results for target gas detected on the sensing electrode <NUM> for a range of membrane <NUM> porosities. Again, the porosity is represented by "p" where a porosity of <NUM> is equivalent to the membrane <NUM> effectively not being present and the porosity of <NUM> is equivalent to the membrane <NUM> being significantly blocked. As shown in <FIG>, as the membrane <NUM> becomes more restricted, the response time of the gas sensor <NUM> slows down and the steady state signal decreases. During normal operating mode, the capillary <NUM> should be the most restrictive portion of the gas sensor <NUM>. That is, the capillary <NUM> restricts the target gas more than the membrane <NUM>. As the membrane <NUM> becomes clogged or blocked, the membrane <NUM> will be the more restricting section of the gas sensory <NUM>.

<FIG> illustrates the gas sensitivity during normal operating modes verse the gas sensitivity during the diagnostic modes. In particular, <FIG> compares the gas sensitivity during normal operation modes with the integrated diagnostic charge during diagnostic modes. As the membrane <NUM> becomes more blocked or restricted (e.g., the porosity of the membrane <NUM> decreases), the gas sensitivity decreases and the diagnostic charge increases. The diagnostic mode is very sensitive. For instance, when the porosity of the membrane <NUM> has decreased to <NUM>, the gas sensitivity is still <NUM>% of its original value and the diagnostic signal has increased three times (3x). Thus, the gas sensor <NUM> can provide an advanced warning of changes in the condition of the membrane <NUM> and capillary <NUM>.

With the test gas diffusion path <NUM>, the membrane <NUM> may be considerably restricted before the gas sensor <NUM> gas sensitivity is affected. The disclosed gas sensor <NUM> and method of using the same may be able to detect restriction of the membrane <NUM> long before the membrane <NUM> becomes restricted enough to limit gas sensitivity, thereby providing an advance warning that the gas sensor <NUM> needs maintenance.

The disclosed gas sensor <NUM> and method of using the same may enable compensation to be applied to the gas sensor <NUM> to allow for increased restriction by membrane <NUM>. In extreme cases (e.g., the membrane <NUM> is highly restricted), failure may be flagged. The disclosed gas sensor <NUM> and method of using the same may also detect torn or missing membrane <NUM>. For example, the test gas pulse reaching the sensing electrode <NUM> may be much lower than considered normal for the respective membrane <NUM>. The disclosed gas sensor <NUM> and method of using the same may independently test (and hence compensate for and/or flag failure of) restriction of the membrane <NUM> and the capillary <NUM> using a single test. For instance, the diagnostic mode may produce a total integrated charge (e.g., the main measure for membrane <NUM> restriction), the peak current (e.g., the main measure for capillary <NUM> restriction), and the rates of rise and decay of detected test gas pulses.

The gas sensor may also include various alarms, such as visual or audible alarms, for notifying others that a gas has been identified, failure mode identified in the gas sensor, maintenance needed for the gas sensor, low power mode or loss of power, etc..

The gas sensor may include additional electrodes, chambers, membranes, capillaries, etc. arranged in various configurations without deviated from the present invention. The gas sensor may monitor the presence of various gases, such as carbon monoxide, and may monitor multiple gases.

<FIG> illustrates a flow diagram of an example system in accordance with some embodiments discussed herein. In particular, <FIG> illustrates a method of monitoring gas restriction in a gas sensor <NUM>. In the embodiment illustrated in <FIG>, the method <NUM> includes causing a test gas to travel through a test gas diffusion path disposed in a gas sensor <NUM> and determining a degree of restriction in the gas sensor <NUM>. The test gas diffusion path may be disposed between a membrane and a sensing electrode and is configured such that when the test gas travels through the test gas diffusion path from the inlet to the outlet, the test gas comes in contact with the membrane prior to coming in contact with the sensing electrode. Determining a degree of restriction in the gas sensor <NUM> may include receiving a test gas signal from the sensing electrode and integrating the test gas signal and/or determining a peak current in the test gas signal <NUM>. For instance, the degree of restriction in the gas sensor may be determined from integrating the test gas signal, which would indicate the degree of restriction of the membrane. The degree of restriction may be determined by determining the peak current in the test gas signal, which would indicate the degree of restriction of the capillary. The method <NUM> may be repeated on a periodic basis or as needed to monitor the gas sensor <NUM>. In some embodiments, the method <NUM> may include replacing and/or cleaning the membrane, capillary, or other portion of the gas sensor in response to the degree of restriction. In some embodiments, the method <NUM> may include generating a restriction compensation to apply to a target gas signal in response to the degree of restriction. For instance, if the degree of restriction indicates that only a portion of the membrane and/or capillary is restricted, then a restriction compensation (e.g., a correction factor) may be applied to a target gas signal to account for the portion of the membrane and/or capillary being restricted. Such compensation may allow for accurate target gas sensing by the gas sensor with less maintenance and/or operator intervention.

Claim 1:
A gas sensor (400A-400N) for detecting target gas and test gas, comprising:
a housing (<NUM>) defining an opening (<NUM>) to an external environment;
a sensing electrode (<NUM>) disposed in the housing (<NUM>) and configured to generate a test gas signal when the sensing electrode (<NUM>) is in contact with a test gas;
a membrane (<NUM>) disposed in the housing (<NUM>) between the sensing electrode (<NUM>) and the opening (<NUM>) in the housing (<NUM>), wherein the membrane (<NUM>) is at least partially exposed to the external environment;
a test gas diffusion path (<NUM>) defined in the housing (<NUM>) for the test gas to travel in the gas sensor (400A-400N) and comprising an inlet (<NUM>) and an outlet (<NUM>); and
a capillary (<NUM>) disposed between the sensing electrode (<NUM>) and the outlet (<NUM>) of the test gas diffusion path (<NUM>),
wherein the test gas diffusion path (<NUM>) is disposed between the membrane (<NUM>) and the capillary (<NUM>), the test gas diffusion path (<NUM>) including a first wall (<NUM>) and a second wall (<NUM>) that define the test gas diffusion path (<NUM>), the first wall (<NUM>) defining a first test gas diffusion path opening (<NUM>) to expose the test gas to the membrane (<NUM>), the second wall (<NUM>) defining a second test gas diffusion path opening (<NUM>) to expose the test gas to the capillary (<NUM>) and sensing electrode (<NUM>), the first test gas diffusion path opening (<NUM>) disposed prior to the second test gas diffusion path opening (<NUM>) along the test gas diffusion path (<NUM>) in a direction of flow from the inlet (<NUM>) of the test gas diffusion path (<NUM>) to the outlet (<NUM>) of the test gas diffusion path (<NUM>), such that when the test gas travels through the test gas diffusion path (<NUM>) from the inlet (<NUM>) to the outlet (<NUM>), the test gas comes in contact with the membrane (<NUM>) prior to coming in contact with the capillary (<NUM>) and then the sensing electrode (<NUM>),
wherein a total amount of the test gas signal is higher when the membrane (<NUM>) has a high degree of restriction of gas access compared to the total amount of the test gas signal when the membrane (<NUM>) has a low degree of restriction of gas access, and
wherein a magnitude of the test gas signal indicates a degree of restriction of gas access by the capillary (<NUM>).