Method and apparatus for rapid initialization of gas concentration monitoring

Abstract

The present invention is entitled "Method and Apparatus for Rapidly Initializing Gas Concentration Monitoring." The present invention provides a sensor assembly for monitoring gas concentration and a method thereof. The sensor assembly includes a startup sensor and a long-term operation sensor. The startup sensor is characterized by a first power-on cycle, and the long-term operation sensor is characterized by a second power-on cycle that is longer than the first power-on cycle. The sensor assembly also includes a controller in communication with the startup sensor and the long-term operation sensor. The controller is configured to power on the startup sensor and the long-term operation sensor. The controller is further configured to, upon expiration of the second power-on cycle, power off the startup sensor and monitor gas concentration via the long-term operation sensor. The present invention also provides a corresponding method for monitoring gas concentration.

Description

Technical Field

[0001] The exemplary embodiments relate generally to gas monitoring methods and related apparatus, and more particularly to methods and related apparatus for rapid initialization of gas concentration monitoring. Background Art

[0002] Modern gas sensors come in a variety of forms, which may have large power consumption requirements or require longer initialization times to achieve steady-state operation capable of generating accurate gas concentration measurements. Traditional oxygen sensors utilize lead electrodes and consume little or no power during operation. However, these lead-based oxygen concentration sensors have a limited service life because the electrodes are consumed during operation. In addition, due to health concerns, lead-based devices, including these lead-based oxygen concentration sensors, have been phased out over time. Alternative technologies for oxygen sensors are not limited by the same shorter service lives as the original lead-based sensors, however, these alternative technologies are characterized by higher power consumption levels, which require these sensors to be connected to a continuous power source or a larger onboard power source (e.g., a battery) to enable the sensor to be used for a longer period of time. Through hard work, ingenuity, and innovation, many of these recognized problems have been solved by the methods and apparatus of the present disclosure. Summary of the Invention

[0003] Exemplary embodiments of the present disclosure relate to fast-initialization gas concentration monitoring. In the exemplary embodiments, a sensor assembly for monitoring gas concentration is provided. The sensor assembly includes a startup sensor and a long-term operation sensor. The startup sensor is characterized by a first power-on cycle, and the long-term operation sensor is characterized by a second power-on cycle that is longer than the first power-on cycle. The sensor assembly also includes a controller in communication with the startup sensor and the long-term operation sensor. The controller is configured to power on the startup sensor and the long-term operation sensor. The controller is further configured to power off the startup sensor upon expiration of the second power-on cycle and monitor gas concentration via the long-term operation sensor.

[0004] In some embodiments, the startup sensor defines a startup capillary size, and the long-term operation sensor defines a long-term operation capillary size. In such embodiments, the startup capillary size is larger than the long-term operation capillary size. In some embodiments, the second power-on period is 10 to 20 minutes. In some embodiments, the startup sensor remains off until the long-term operation sensor is fully powered off and restarted. In some embodiments, the startup sensor and the long-term operation sensor are disposed within a single sensor housing.

[0005] In some embodiments, the startup sensor and the long-term operation sensor are defined within the dual sensor. Thus, the dual sensor defines a startup electrode and a long-term operation electrode having a single counter electrode. In some embodiments, the startup electrode is capable of operating in conjunction with the startup capillary, and the long-term operation electrode is capable of operating in conjunction with the long-term operation capillary. In some embodiments, the startup sensor defines the startup electrode, and the long-term operation sensor defines the long-term operation electrode. In such embodiments, the startup electrode is capable of operating in conjunction with a PTFE membrane having a first thickness, and the long-term operation electrode is capable of operating in conjunction with a PTFE membrane having a second thickness greater than the first thickness. In some embodiments, the dual sensor communicates with a controller configured to switch between a dual power-on state and a long-term operation state. In such embodiments, the dual power-on state is characterized as a situation where both the startup sensor and the long-term operation sensor are powered on, and the long-term operation state is characterized as a situation where the startup sensor is powered off and the long-term operation sensor is powered on.

[0006] In some embodiments, the first power-on period is less than one minute. In some embodiments, the startup sensor operates at a higher current than the long-term operation sensor. In some embodiments, the startup sensor operates at a current of 400 to 1000 microamperes, and the long-term operation sensor operates at a current of 50 to 200 microamperes. In some embodiments, at least one of the startup sensor or the long-term operation sensor is an oxygen sensor or a partial pressure sensor. In some embodiments, the startup sensor and the long-term operation sensor are two different sensors having different components that communicate with the controller.

[0007] In an exemplary embodiment, a method for monitoring gas concentration is provided. The method includes energizing a startup sensor and a long-term operation sensor. The startup sensor is characterized by a first energization cycle, and the long-term operation sensor is characterized by a second energization cycle that is longer than the first energization cycle. The method further includes monitoring the gas concentration via the startup sensor during the second energization cycle of the long-term operation sensor. The method further includes deenergizing the startup sensor and monitoring the gas concentration via the long-term operation sensor upon expiration of the second energization cycle.

[0008] In some embodiments, the startup sensor defines a startup capillary size, and the long-term operation sensor defines a long-term operation capillary size. In such embodiments, the startup capillary size is larger than the long-term operation capillary size. In some embodiments, the second power-on period is 10 to 20 minutes. In some embodiments, the startup sensor remains off until the long-term operation sensor is fully powered off and restarted. In some embodiments, the startup sensor and the long-term operation sensor are disposed within a single sensor housing.

[0009] In some embodiments, the startup sensor and the long-term operation sensor are defined within a dual sensor. In such embodiments, the dual sensor defines a startup electrode and a long-term operation electrode having a single counter electrode. In some embodiments, the startup electrode is disposed near the startup capillary, and the long-term operation electrode is disposed near the long-term operation capillary. In some embodiments, the startup sensor defines the startup electrode, and the long-term operation sensor defines the long-term operation electrode. In such embodiments, the startup electrode is operable in conjunction with a PTFE membrane having a first thickness, and the long-term operation electrode is operable in conjunction with a PTFE membrane having a second thickness greater than the first thickness. In some embodiments, the dual sensor communicates with a controller configured to switch between a dual power-on state and a long-term operation state. In such embodiments, the dual power-on state is characterized as a situation where both the startup sensor and the long-term operation sensor are powered on, and the long-term operation state is characterized as a situation where the startup sensor is powered off and the long-term operation sensor is powered on.

[0010] In some embodiments, the first power-on period is less than one minute. In some embodiments, the startup sensor operates at a higher current than the long-term operation sensor. In some embodiments, the startup sensor operates at a current of 400 to 1000 microamperes, and the long-term operation sensor operates at a current of 50 to 200 microamperes. In some embodiments, at least one of the startup sensor or the long-term operation sensor is an oxygen sensor or a partial pressure sensor. In some embodiments, the startup sensor and the long-term operation sensor are two different sensors having different components that communicate with the controller.

[0011] The above summary of the invention is provided only for the purpose of summarizing some exemplary embodiments to provide a basic understanding of some aspects of the present disclosure. Therefore, it should be understood that the above embodiments are merely examples and should not be construed as narrowing the scope or essence of the present disclosure in any way. It should be understood that the scope of the present disclosure also encompasses many possible embodiments in addition to those summarized here, some of which will be further described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Having thus generally described certain exemplary embodiments of the present disclosure, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and in which:

[0013] Figure 1 is a block diagram of an apparatus configured according to an exemplary embodiment of the present disclosure;

[0014] Figure 2 To illustrate exemplary embodiments according to the present disclosure, such as Figure 1 a flowchart of operations performed by the device;

[0015] Figure 3 Another flowchart illustrating exemplary operations of an apparatus according to an exemplary embodiment of the present disclosure;

[0016] Figure 4A and Figure 4B is an exemplary startup sensor in the case where the startup sensor and the long-term operation sensor are different sensors ( Figure 4A ) and an exemplary long-term operating sensor ( Figure 4B );

[0017] Figure 5 is an exemplary dual sensor in an exemplary embodiment, wherein the startup sensor and the long-term operation sensor share a common housing with a common counter electrode;

[0018] Figure 6A is a graph illustrating current readings of an exemplary startup sensor and an exemplary long-term operation sensor from the time the sensor is powered on until the power cycle of the long-term operation sensor is complete; and

[0019] Figure 6B is the oxygen concentration, which is based on Figure 6A Current readings of an exemplary startup sensor and an exemplary long-term operation sensor from the time these sensors are powered on until the power cycle of the long-term operation sensor is completed. DETAILED DESCRIPTION

[0020] Some embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all, embodiments are shown. Indeed, various embodiments 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. Throughout, like reference numerals refer to like elements. As used herein, the terms "data," "content," "information," and similar terms are used interchangeably to refer to data that can be generated, processed, transmitted, received, and / or stored in accordance with embodiments of the present disclosure. Accordingly, the use of any such terms should not be construed as limiting the spirit and scope of the embodiments of the present disclosure.

[0021] Various embodiments described herein implement an energy-efficient, fast-initializing gas sensor device that features a fast startup sequence that enables the device to easily and quickly change between a powered-on configuration and a powered-off configuration to save energy during periods of non-use, such that the device can be powered up quickly to begin generating accurate samples and not use excessive energy during extended operation.

[0022] Exemplary device configurations

[0023] Figure 11 is a schematic diagram of an exemplary apparatus configured to perform the operations described herein. Apparatus 10 is an exemplary embodiment that may be embodied by or otherwise associated with any of a variety of computing devices, including or otherwise associated with a device configured to provide advanced sensing features, which may include sensor assembly 24. For example, apparatus 10 may be embodied as an oxygen concentration sensor configured to detect the concentration of oxygen in a gaseous fluid (e.g., air).

[0024] The device 10 may include, be associated with, or otherwise communicate with a communication interface (not shown), a processor 14, a memory device 16, and a sensor assembly 24. In some embodiments, the processor 14 (and / or a coprocessor or any other processing circuitry that assists the processor or is otherwise associated with the processor) may communicate with the memory device 16 (e.g., a non-transitory memory including one or more volatile memories and / or non-volatile memories). The memory device may be configured to store information, data, content, applications, instructions, etc. for enabling the device to perform various functions according to exemplary embodiments of the present invention.

[0025] The processor 14 may be embodied in a variety of different ways. For example, the processor may be embodied as one or more of a variety of hardware processing devices, such as a coprocessor, a microprocessor, a controller, a digital signal processor (DSP), a processing element with or without an accompanying DSP, or various other processing circuits, including integrated circuits such as ASICs (application-specific integrated circuits), FPGAs (field-programmable gate arrays), microcontroller units (MCUs), hardware accelerators, dedicated computer chips, etc.

[0026] In an exemplary embodiment, the processor 14 can be configured to execute instructions stored in the memory device 16 or otherwise accessible to the processor. Alternatively or in addition, the processor can be configured to perform hard-coded functions. Thus, whether configured by hardware methods or software methods, or by a combination thereof, a processor can represent an entity (e.g., physically embodied in circuit form) capable of performing operations in accordance with embodiments of the present invention while being configured accordingly.

[0027] In various embodiments, the device 10 also includes a user interface element (not shown) that includes one or more of: a display element (e.g., an LCD display, an LED display, a series of individually illuminated indicators, etc.), a sound output device (e.g., providing audio-based indications of various functions of the device), and / or one or more input elements (e.g., a touch screen device, a button array, etc.) for receiving user input to control various aspects of the operation of the device (e.g., turning the device on and / or off).

[0028] Device 10 may include a sensor assembly 24 comprising a startup sensor 20 and a long-term operation sensor 22. Startup sensor 20 and long-term operation sensor 22 may each be defined as a sensor capable of determining the gas concentration of one or more gases in a given area. As a specific example, each of startup sensor 20 and long-term operation sensor 22 may include an oxygen concentration sensor (e.g., an oxygen pump sensor). In various embodiments, startup sensor 20 may be characterized as a fast-initializing, high-current-consuming oxygen concentration sensor, and long-term operation sensor 22 may be characterized as a slow-initializing, low-current-consuming oxygen concentration sensor. In other words, if both the long-term operation sensor and the startup sensor are powered on at substantially the same time, startup sensor 20 may be capable of accurately monitoring gas concentration (e.g., oxygen concentration) more quickly than long-term operation sensor 22. In other words, startup sensor 20 is characterized by a first initialization period, which is the period between when the sensor is initialized and when the startup sensor is able to generate accurate oxygen concentration measurements; and long-term operation sensor 22 is characterized by a second initialization period, which is longer than the first initialization period. In various embodiments, the long-term operation sensor 22 can be configured to operate at a lower current than the startup sensor 20, so that less power is required to operate the long-term operation sensor. In other words, the startup sensor 20 is characterized by a first current consumption rate, and the long-term operation sensor 22 is characterized by a second current consumption rate that is lower than the first current consumption rate.

[0029] In various embodiments, the startup sensor 20 may be a capillary limited oxygen sensor, a partial pressure oxygen sensor, etc. In various embodiments, the startup sensor 20 may be configured with a startup sensing electrode 41a (shown in FIG. Figure 4A and Figure 5 In one embodiment, the startup sensing electrode 20 is configured to determine the concentration of a gas (e.g., oxygen concentration) present near the sensing electrode. In an exemplary embodiment, the gas concentration can be determined based on changes in the current drawn by the sensor during operation (e.g., more oxygen results in a higher current). In various embodiments, without power being supplied to the startup sensor 20, the startup sensing electrode can become saturated with gas, such that the startup sensor cannot produce accurate gas concentration readings during the initial "power-on" period due to background current from the saturated target gas (e.g., oxygen). In various embodiments, in some embodiments, a limiting capillary can be defined on or near the startup sensor 20, thereby limiting the amount of gas around the sensor that can reach the startup sensing electrode. The startup capillary 42a can be built into the housing itself or can be an attached component. In various embodiments, the larger the capillary, the higher the current drawn by a given sensor.

[0030] In various embodiments, the startup sensor 20 defines a power-on period, which is characterized as the time period from the time the startup sensor is powered on until the startup sensor is able to monitor gas concentrations in a given area with sufficient accuracy. As described above, while the sensor is powered off (and the sensor is not consuming oxygen already collected therein), oxygen continues to flow into the sensor. Therefore, once the sensor is powered on, the sensor can immediately detect an increase in oxygen concentration during the power-on period, while excess oxygen collected within the sensor is consumed. In certain embodiments, a sensor characterized as having a higher current draw can consume this excess oxygen at a similar rate as a sensor characterized as having a lower current draw, but with a smaller percentage impact on the current (e.g., a higher sensor current provides greater resistance to background current). Over time, the excess oxygen collected within the sensor is consumed at a faster rate than the flow of fresh oxygen into the sensor until the sensor reaches a steady-state operating condition, in which the flow of oxygen into the sensor at least substantially matches the sensor's oxygen consumption rate. Under this steady-state operating condition, the oxygen concentration inside the capillary or diffusion-limited PTFE membrane within the sensor is essentially zero, causing any oxygen entering the sensor to be consumed at a diffusion-limited rate, and thus the oxygen concentration measured by the sensor can be a roughly accurate reading of the ambient concentration. For a given sensor configuration, the duration of the power-on cycle can be at least substantially consistent (e.g., regardless of the length of time the sensor is powered off), and thus the duration of the power-on cycle can be consistent and confined within the sensor's startup sequence. In various embodiments, the duration of the power-on cycle and the characterization of the degree of sufficient accuracy considered to be achieved by the sensor (thereby determining when the sensor reading can be assumed to be accurate) can be based on the sensor itself (e.g., sensors can have different sensitivities and, therefore, different inherent accuracies). In various embodiments, sufficient accuracy can be characterized as the point in time at which the startup sensor begins to accurately generate gas concentration data (e.g., whenever sufficient saturated oxygen within the sensor has decayed such that the current reading is not significantly affected by the background current required to decay the oxygen). In some embodiments, the duration of the power-on cycle can be defined so that the startup sensor 20 operates within the "dead band" of oxygen readings, thereby ensuring that the current-based oxygen reading is within 0.5% of the actual oxygen concentration. As described above, sensors characterized by a higher current draw are less sensitive to background current due to excess oxygen accumulation within the sensor, and therefore such sensors are characterized by having a shorter duration power-on cycle. In various embodiments, the power-on cycle can approximate a preset duration after the startup sensor is turned on. In some embodiments, the preset duration can be approximated based on the assumption that the target gas (e.g., oxygen) fully saturates the sensing electrode when the sensor is powered on.In various embodiments, the preset time period can be set based on an understanding of the rate at which the sensor consumes the existing oxygen within the capillary tube until some or all of the "built-up" oxygen is completely consumed. In various embodiments, the startup period can be approximately a preset time period of about 30 seconds.

[0031] As described below, the power-on period of the startup sensor 20 can be characterized as being shorter than the power-on period of the long-term operating sensor 22. In various embodiments, the startup sensor 20 can be configured to have a power-on period of less than one minute. For example, the power-on period of the startup sensor 20 can be approximately 30 seconds. In various embodiments, the length of the power-on period of the startup sensor 20 can be based on the operating current of the startup sensor. In various embodiments, a higher current for the startup sensor allows for faster sensor initialization, in part due to the higher current's greater resistance to background current. For example, the higher the operating current, the shorter the time required until the background current sufficiently decreases to provide an accurate current reading.

[0032] As just one non-limiting example, the operating current of the startup sensor may be from about 400 microamperes to about 1000 microamperes. As another non-limiting example, the operating current of the startup sensor may be from about 400 microamperes to about 800 microamperes. As another non-limiting example, the operating current of the startup sensor may be from about 400 microamperes to about 600 microamperes. For example, the operating current of the startup sensor may start at about 500 microamperes. In various embodiments, the operating current may be affected by the capillary size of the startup sensor. In some embodiments, the startup capillary 42a may be from about 40 microns to about 100 microns. For example, the startup capillary 42a may be about 50 microns. As described herein, in some embodiments (for example, where the startup sensor 20 is a partial pressure oxygen sensor), the startup sensor 20 may not have a restrictive capillary, but instead may have a solid polytetrafluoroethylene (PTFE) membrane that affects the current therein.

[0033] In various embodiments, the long-term operation sensor 22 may be a capillary limited oxygen sensor, a partial pressure oxygen sensor, etc. In various embodiments, the long-term operation sensor may be configured with a long-term operation sensing electrode 41a (shown in FIG. Figure 4B and Figure 5In one embodiment, the long-term operating sensing electrode 22 is configured to determine the concentration of a gas (e.g., oxygen concentration) present in the vicinity of the sensing electrode. In an exemplary embodiment, the gas concentration can be determined based on changes in the current drawn by the sensor during operation (e.g., more oxygen results in a higher current). In various embodiments, without power being supplied to the long-term operating sensor 22, the long-term operating sensing electrode can become saturated with gas, preventing the long-term operating sensor from producing accurate gas concentration readings during the initial "power-on" cycle. In various embodiments, a limiting capillary can be defined on or near the long-term operating sensor, thereby limiting the amount of gas around the sensor that can reach the startup sensing electrode. The long-term operating capillary 42b can be built into the housing itself or can be an attached component. In various embodiments, the smaller the capillary, the lower the current consumption of a given sensor.

[0034] In various embodiments, a long-term operating sensor may have a power-on period, characterized as the time period from the time the long-term operating sensor is powered on until the long-term operating sensor can accurately monitor gas concentrations in a given area with sufficient accuracy. As described above, while the sensor is powered off (and the sensor is not consuming oxygen already collected therein), oxygen continues to flow into the sensor. Therefore, once the sensor is powered on, the sensor can immediately detect an increase in oxygen concentration during the power-on period, while the excess oxygen collected within the sensor is consumed. In certain embodiments, a sensor characterized as having a higher current draw can consume this excess oxygen at a similar rate as a sensor characterized as having a lower current draw, but with a smaller percentage impact on the current (e.g., a higher sensor current provides greater resistance to background current). Over time, the excess oxygen collected within the sensor is consumed at a faster rate than the flow of fresh oxygen into the sensor until the sensor reaches a steady-state operating condition, in which the flow of oxygen into the sensor at least substantially matches the sensor's oxygen consumption rate. Under this steady-state operating condition, the oxygen concentration inside the capillary or diffusion-limited PTFE membrane within the sensor is essentially zero, causing any oxygen entering the sensor to be consumed at a diffusion-limited rate, and thus the oxygen concentration measured by the sensor can be a roughly accurate reading of the ambient concentration. For a given sensor configuration, the duration of the power-on period can be at least substantially consistent (e.g., regardless of the length of time the sensor is powered off), and thus the duration of the power-on period can be consistent and confined within the sensor's startup sequence. In various embodiments, the duration of the power-on period and the characterization of a sufficient degree of accuracy attributed to the sensor (thereby determining when the sensor reading can be assumed to be accurate) can be based on the sensor itself (e.g., sensors can have different sensitivities and, therefore, different inherent accuracies). In various embodiments, sufficient accuracy can be characterized as the point in time at which the background current has been reduced to a sufficient degree compared to the sensor's operating current (e.g., the point in time at which the transient startup current, due to saturated oxygen, decays to a level that is no longer significant compared to the sensor's steady-state diffusion-limited output current). For example, in order to achieve a signal measurement accuracy of 1%, the transient background current must be less than 1% of the normal measurement current, so that, for example, a sensor with a 100 microamp output in air (e.g., the long-term operation sensor 22) will require a background current of less than 1 microamp for 1% accuracy, while a sensor with a 500 microamp output in air (e.g., the startup sensor 20) will provide 1% accuracy at a background current of 5 microamps.Because background current decays exponentially, it may take much longer for the background signal to decay to 1 microamp than to decay to 5 microamps (e.g., although the oxygen in the startup sensor 20 and the long-term operation sensor 22 may decay at approximately the same rate, the background current caused by the oxygen will interfere with the accuracy of the long-term operation sensor for a longer time than the startup sensor).

[0035] In various embodiments, the power-on period can approximate a preset duration after the long-running sensor 22 is turned on. In some embodiments, the preset duration can be approximated based on the assumption that the target gas (e.g., oxygen) completely saturates the sensing electrode when the sensor is powered on. In various embodiments, the preset duration can be defined at least in part based on an understanding of the rate at which the sensor consumes the oxygen present in the capillary tube until at least a portion (e.g., all) of the "accumulated" oxygen is completely consumed. In various embodiments, the power-on period of the long-running sensor 22 can be greater than the power-on period of the startup sensor 20. In various embodiments, the long-running sensor can be configured to have a power-on period of approximately 10 to 20 minutes. For example, the power-on period of the startup period can be approximately 15 minutes. In various embodiments, the power-on period length can be based on the operating current of the long-running sensor.

[0036] Because the power-on period is defined as the time period during which equilibrium steady-state conditions are reached within the sensor, such that the oxygen concentration within the sensor at least substantially matches the oxygen concentration in the surrounding environment, the capillary size (e.g., diameter) influences the duration of the power-on period. Specifically, a larger capillary (e.g., larger diameter) exhibits a greater diffusion-limited current response to oxygen, thereby making transient background current due to the depletion of oxygen accumulated within the sensor less significant over time. This results in a shorter duration between sensor initialization and the time at which the transient background current becomes sufficiently negligible that the sensor reading can be assumed to be an accurate representation of the ambient oxygen concentration. Therefore, startup sensor 20 is configured with a larger capillary than long-term operation sensor 22, resulting in a shorter power-on period for the startup sensor than the long-term operation sensor, but requiring more current during operation. In various embodiments, due in part to the higher sensor current associated with a larger capillary, the increased current allows startup sensor 20 to initialize more quickly. Thus, when the sensor is powered off, the background current caused by oxygen saturating the sensing electrode is a smaller percentage of the total current and, therefore, becomes statistically insignificant more quickly than a long-term operating sensor having a relatively small capillary (e.g., where current readings are considered accurate within 0.5% of the precise current reading). For example, the higher the operating current, the shorter the power-on period. During the power-on period of the long-term operating sensor 22, the long-term operating sensor does not generate accurate oxygen concentration data (e.g., background current readings may affect concentration readings during the power-on period), and therefore the device is configured to utilize data indicating oxygen concentration data of the startup sensor while the long-term operating sensor completes its startup period.

[0037] In various embodiments, the operating current of the long-term operation sensor 22 may be less than that of the startup sensor 20. In various embodiments, the operating current of the long-term operation sensor 22 may be significantly less than that of the startup sensor 20. As a non-limiting example only, the operating current of the long-term operation sensor 22 may be approximately 50 microamperes to approximately 200 microamperes. As another non-limiting example, the operating current of the long-term operation sensor 22 may be approximately 75 microamperes to approximately 150 microamperes. For example, the operating current of the long-term operation sensor 22 may be approximately 100 microamperes. In various embodiments, the operating current may be affected by the capillary size of the long-term operation sensor. Therefore, larger capillary size results in higher current draw for the associated sensor. For example, because the startup sensor has a larger capillary than the long-term operation sensor, the startup sensor 20 may have a higher current draw than the long-term operation sensor 22. In various embodiments, the long-term operation capillary 42b may be approximately 5 micrometers to approximately 15 micrometers. For example, the long-term operation capillary 42b may be approximately 10.5 micrometers. As described herein, in some embodiments (eg, where the long term operation sensor 22 is a partial pressure oxygen sensor), the long term operation sensor 22 may include a polytetrafluoroethylene (PTFE) membrane that affects the oxygen diffusion rate (and therefore the current draw of the sensor).

[0038] In various embodiments, the sensor assembly 24 can be configured as a single dual sensor such that the dual sensor has both a start-up sensing electrode 41a and a long-term operating sensing electrode 41b (e.g., a different capillary feed to each electrode) and a common counter electrode (e.g., Figure 5 In various embodiments, the sensor assembly 24 may be two different sensors (e.g., a startup sensor 20 and a long-term operation sensor 22 both attached to and in communication with the processing circuit 12), as shown. Figure 4A and Figure 4BAs shown. In various embodiments, sensor assembly 24 may comprise two distinct sensors housed within a common housing. Whether sensor assembly 24 comprises multiple individual sensors or a dual sensor, it may be configured with multiple gas chambers 40a, 40b, each housing sensing electrodes. Thus, startup sensor 20 may define a startup capillary 42a, which allows gas therein to enter startup gas chamber 40a. Additionally, long-term operation sensor 22 may define a long-term operation capillary 42b, which allows gas therein to enter long-term operation gas chamber 40b. In various embodiments, startup capillary 42a may be larger than long-term operation capillary 42b, allowing target gas to more easily reach startup sensing electrode 41a, thereby generating a higher current for a given target gas concentration. Consequently, the background current decay of startup sensor 20 has a relatively smaller impact on the measured signal than the background current decay of the smaller output long-term operation sensor 22. Furthermore, sensor assembly 24 may be configured with one or more counter electrodes, which facilitate the flow of current through the sensor by stimulating a reverse reaction. In various embodiments, the counter electrode can also be a reference electrode for deriving a stable reference voltage used to drive the sensing electrodes. In various embodiments, one or more reference electrodes can be provided independently of the counter electrode. For example, where the startup sensor 20 and the long-term operation sensor 22 are different sensors, each sensor can have a different counter electrode and a different reference electrode, whereas where the startup sensor 20 and the long-term operation sensor 22 are in the same housing (e.g., Figure 5 ), there may be a different counter electrode and a different reference electrode used with each sensing electrode. In some embodiments, each of the start electrode 41a and the long-term operation electrode 41b may be associated with a separate different counter electrode 49a, 49b (e.g., where multiple different sensors are provided, such as Figure 4A and Figure 4B Alternatively, the starting electrode 41a and the long-term operation electrode 41b may share the same counter electrode 49 (as shown in FIG. Figure 5 ). In such embodiments, the startup sensor 20 and the long-term operation sensor 22 may share the same electrolyte 48. Alternatively, in some cases, such as when the startup sensor 20 and the long-term operation sensor 22 are separate sensors, the startup sensor 20 may have a different electrolyte 48a and the long-term operation sensor 22 may have a different electrolyte 48b, as shown. Figure 4A and Figure 4BAs shown. In various embodiments, sensing electrodes 41a, 41b may use PTFE tapes 44a, 44b. In various embodiments, one or both of the PTFE tapes 44a and 44b may be porous (for example, in the case of a capillary-limited oxygen sensor), or one or both of the PTFE tapes 44a and 44b may be solid PTFE tapes (for example, in the case of a partial pressure oxygen sensor where the tape itself is a diffusion limiter). In some embodiments, the PTFE tapes 44a and 44b may be different types of tapes (for example, one sensor may have a porous PTFE tape, while the other sensor may have a solid PTFE tape). In various embodiments, where one or both of these sensors are partial pressure sensors, a given partial pressure sensor may not be configured with a capillary, so that the diffusion limit (sensitivity) is determined by the solid PTFE membrane. For example, a thicker PTFE membrane results in a smaller current. Therefore, if both sensors are partial pressure sensors, the long-term operation sensor may have a thicker solid PTFE membrane than the startup sensor.

[0039] Now see Figure 2 Exemplary embodiments of the present disclosure include a flow chart for processing circuitry 12, processor 14, sensor assembly 24, etc., to monitor and determine gas concentrations in an energy-efficient manner. Various embodiments of the present disclosure allow the sensor assembly 24 to be powered off during periods without requiring a lengthy initialization time for the sensor. Various embodiments of the present disclosure allow the sensor assembly 24 to begin monitoring gas concentrations shortly after power is applied to the sensor assembly without consuming significant amounts of power during extended operation.

[0040] Now see Figure 2At block 200, a method for monitoring gas concentration includes energizing a startup sensor and a long-term operation sensor. In some embodiments, startup sensor 20 and long-term operation sensor 22 may be energized substantially simultaneously. As described above, both startup sensor 20 and long-term operation sensor 22 may each have a power-on period, characterized as a period of time during which each sensor is able to monitor gas concentration in a given area with sufficient accuracy. In various embodiments, if sensor assembly 24 (e.g., startup sensor 20 and / or long-term operation sensor 22) is powered off (e.g., the sensor is not receiving current), the sensing electrodes may receive ambient gas, resulting in an inaccurate initial reading when a given sensor is powered on (e.g., sufficient current must flow through the sensor to remove accumulated target gas from the electrolyte and near the sensing electrodes before the sensor can generate accurate data). In various embodiments, a smaller capillary inlet of the sensor may result in a shorter power-on period due to the greater resistance of the higher operating current to background current. In various embodiments, the startup sensor 20 may be configured with a larger capillary than the long-term operation sensor 22, such that the startup sensor may require a higher operating current than the long-term operation sensor, but require a shorter power-on period than the long-term operation sensor.

[0041] Now see Figure 2 At block 210, the method includes monitoring the gas concentration in a given area via the startup sensor 20 during the period of power-on of the long-term operating sensor 22. In various embodiments, the startup sensor 20 may be configured to have a shorter power-on period, such that the startup sensor can quickly and accurately monitor the gas concentration in the given area after power-on. In various embodiments, the startup sensor 20 may have a shorter power-on period than the long-term operating sensor 22. In various embodiments, the startup sensor may have a significantly shorter power-on period than the long-term operating sensor. For example, the startup sensor may be able to monitor gas concentration within one minute (e.g., approximately 30 seconds) of power-on, while the long-term operating sensor may take more than fifteen minutes to be able to monitor gas concentration.

[0042] Now see Figure 2At block 220 , the method includes de-energizing the startup sensor 20 when the power cycle of the long-term operating sensor 22 is complete or nearly complete. In various embodiments, the device 10 may be configured to allow for continuous monitoring of gas concentrations such that the startup sensor continues to operate concurrently with the long-term operating sensor for at least a period of time after the power cycle of the long-term operating sensor is complete. In various embodiments, the startup sensor may be de-energized shortly before the power cycle of the long-term operating sensor is complete. In various embodiments, the startup sensor may be de-energized substantially simultaneously with the completion of the power cycle of the long-term operating sensor, allowing monitoring to continue with minimal excess energy. In some embodiments, there may be situations where the power cycle of the startup sensor 20 and the power cycle of the long-term operating sensor 22 may have completed, and both sensors may continue to be energized for at least a short period of time (e.g., to verify that the output of the long-term operating sensor is sufficiently stable to de-energize the startup sensor 20, as the output of the startup sensor 20 may be more stable when the power cycle of the long-term operating sensor is complete or nearly complete). In various embodiments, the startup sensor 20 may be used to confirm that the long-term operating sensor 22 can accurately monitor gas. In some embodiments, power can be saved by actively adjusting the power-on time of the activation sensor 20 .

[0043] Now see Figure 2 At block 230, the method includes monitoring the gas concentration in the given area via the long-term operating sensor 22 in the event that the startup sensor 20 is powered off. In various embodiments, upon completion of the power cycle of the long-term operating sensor 22, the long-term operating sensor 22 is capable of accurately monitoring the gas concentration in the given area using less power than required by the startup sensor 20. In various embodiments, the long-term operating sensor 22 may continue to operate until the device 10 is powered off (e.g., the device 10 may be powered off at night). In the event that the device 10 is powered off, when the device is subsequently powered back on, operations may resume at block 200 (e.g., both the startup sensor 20 and the long-term operating sensor 22 are powered on, and the power cycle of each begins).

[0044] Figure 3 An exemplary flow chart illustrating exemplary device operations according to exemplary embodiments is shown. The operations described herein are similar to those described herein. Figure 2 In various embodiments, the operations may be performed via processing circuitry 12, sensor assembly 24, etc. Figure 3In blocks 300 and 310, while device 10 is powered off, device 10 may initialize, and as part of this initialization process, both startup sensor 20 and long-term operation sensor 22 may be powered on. In various embodiments, as described above, once the power-on cycle of startup sensor 20 is complete (e.g., typically less than one minute), the operations of block 320 occur. As shown, startup sensor 20 typically operates by monitoring gas concentration (e.g., as shown in block 320A), while long-term operation sensor 22 continues its power-on cycle (e.g., as shown in block 320B, the long-term operation sensor may be powered on but unable to generate accurate gas concentrations due to background current). In various embodiments, after a set period of time (e.g., as shown in block 330), startup sensor 20 may be powered off, and long-term operation sensor 22 may monitor gas concentration. In various embodiments, the set period of time may be based on the power-on cycle of the long-term operation sensor. For example, if the power-on cycle of the long-term operation sensor is approximately 15 minutes, the set period of time may be at or near 15 minutes, as shown. Figure 3 Block 340 shows the long term operating state of the device 10, such that the long term operating sensor monitors gas concentration (eg, as shown in block 340B), and sensor power down is initiated (eg, as shown in block 340A).

[0045] Figure 6A An exemplary current reading of 500 microamps for the startup sensor 20 and 100 microamps for the long-term operation sensor 22 is shown when both sensors are powered on at approximately the same time and the oxygen concentration remains constant at approximately 20.9%. As shown, as the target gas (e.g., oxygen) that saturates the sensing electrodes is consumed, the current of the startup sensor 20 and the long-term operation sensor 22 decreases over time until the current is approximately the sensor signal plus any additional current caused by the actual target gas concentration. As shown in the illustrated embodiment, the current changes for both sensors are approximately the same, but the percentage change in current for the startup sensor 20 is less than the percentage change in current for the long-term operation sensor 22. Therefore, Figure 6B The oxygen readings shown normalize toward the actual oxygen concentration faster for the startup sensor 20 than for the long-term operating sensor 22 .

[0046] Figure 6BThe effect of the lower current draw on oxygen concentration readings for the long-term sensor 22 is shown. As shown, the oxygen concentration readings from both sensors initially exceed 20.9% oxygen due to background current drawn by the saturated target gas from the power-off period. As saturated target gas (e.g., oxygen) is consumed by both sensors (e.g., at approximately the same rate), the startup sensor 20 normalizes toward a 20.9% oxygen concentration reading faster than the long-term sensor 22. For example, the oxygen reading for the startup sensor 20 normalizes to within 0.5% oxygen concentration in approximately 30 seconds (e.g., the power-on period of the startup sensor), while the oxygen reading for the long-term sensor 22 normalizes to within 0.5% oxygen concentration much later (e.g., the power-on period of the long-term sensor may be approximately 15 minutes). As described herein, the startup sensor 20 may be powered off after the long-term sensor 22 has normalized to within 0.5% oxygen concentration.

[0047] Various embodiments described herein implement an energy-efficient, fast-initialization gas sensor device that allows the device to be powered down during periods of non-use to conserve energy, while also allowing the device to be quickly powered up during extended periods of operation without using excessive energy.

[0048] As mentioned above, Figure 2 and Figure 3 Flowcharts illustrating various aspects of an apparatus 10 and method according to exemplary embodiments of the present invention are shown. It should be understood that each block in the flowchart, and combinations of blocks in the flowchart, can be implemented by various means (such as hardware, firmware, processors, circuits, and / or other devices associated with the execution of software comprising one or more computer program instructions). For example, one or more of the above processes may be embodied by computer program instructions stored and executed via a memory of the apparatus.

[0049] The blocks in the flowchart support combinations of means for performing the specified functions and combinations of operations for performing the specified functions. It will also be understood that one or more blocks in the flowchart and combinations of blocks in the flowchart may be implemented by a hardware-based special-purpose computer system that performs the specified functions or a combination of special-purpose hardware and computer instructions.

[0050] In some embodiments, some of the operations described above may be modified or further amplified. In addition, in some embodiments, additional optional operations may also be included. The modification, addition, or amplification of the operations described above may be performed in any order and in any combination.

[0051] Those skilled in the art to which the present invention belongs will think of many modifications and other embodiments of the present invention as set forth herein, having benefited from the teachings presented in the foregoing description and the associated drawings. Therefore, it should be understood that the present invention is not limited to the specific embodiments disclosed, and modifications and other embodiments are intended to be included within the scope of the appended claims. In addition, although the foregoing description and the associated drawings describe exemplary embodiments in the context of certain exemplary combinations of elements and / or functions, it should be understood that different combinations of elements and / or functions may be provided by alternative embodiments without departing from the scope of the appended claims. In this regard, for example, it is also conceivable to combine elements and / or functions that are different from those explicitly described above, as may be shown in some of the appended claims. Although specific terms are employed herein, they are used only in a general and descriptive sense, and not for the purpose of limitation.

Claims

1. A sensor assembly for monitoring gas concentration, the sensor assembly comprising: a startup sensor and a long-term operation sensor, wherein the startup sensor is characterized by a first power-on cycle and the long-term operation sensor is characterized by a second power-on cycle that is longer than the first power-on cycle; and a controller in communication with the startup sensor and the long-term operation sensor, The controller is configured to: energizing the startup sensor and the long-term operation sensor simultaneously, During the second power-on period of the long-term operation sensor, monitoring the gas concentration via the startup sensor, and Upon expiration of the second power cycle, the startup sensor is de-energized and the gas concentration is monitored via the long-term operation sensor.

2. The sensor assembly of claim 1 , wherein the startup sensor defines a startup capillary size and the long-term operation sensor defines a long-term operation capillary size, and wherein the startup capillary size is from 40 microns to 100 microns and larger than the long-term operation capillary size.

3. The sensor assembly of claim 1 , wherein the startup sensor defines a startup electrode and the long-term operation sensor defines a long-term operation electrode, wherein the startup electrode is operable in conjunction with a PTFE membrane having a first thickness and the long-term operation electrode is operable in conjunction with a PTFE membrane having a second thickness greater than the first thickness.

4. A method for monitoring gas concentration, the method comprising: energizing a startup sensor and a long-term operation sensor simultaneously, wherein the startup sensor is characterized by a first energization period and the long-term operation sensor is characterized by a second energization period that is longer than the first energization period; monitoring gas concentration via the startup sensor during the second power-on cycle of the long-term operation sensor; and Upon expiration of the second power cycle, the startup sensor is de-energized and the gas concentration is monitored via the long-term operation sensor.

5. The method of claim 4, wherein the startup sensor defines a startup capillary size and the long-term operation sensor defines a long-term operation capillary size, and wherein the startup capillary size is from 40 microns to 100 microns and larger than the long-term operation capillary size. The method of claim 4 , wherein the second power-on period is 10 to 20 minutes, and the first power-on period is shorter than one minute.

7. The method of claim 4, wherein the startup sensor remains off until the long-term operation sensor is completely powered off and restarted.

8. The method of claim 4, wherein the startup sensor defines a startup electrode and the long-term operation sensor defines a long-term operation electrode, wherein the startup electrode is operable in conjunction with a PTFE membrane having a first thickness and the long-term operation electrode is operable in conjunction with a PTFE membrane having a second thickness greater than the first thickness.

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