Method and device for measuring humidity using an electrochemical gas sensor

Abstract

The invention is entitled "Method and apparatus for measuring humidity using an electrochemical gas sensor." The invention discloses a gas detection apparatus and method for measuring humidity using an electrochemical gas sensor. The gas detection apparatus includes an electrolyte-based electrochemical gas sensor and a controller configured to measure an average humidity value within a surrounding environment over a period of time. The average ambient humidity value over the period of time is determined based on an average rate of change of an electrolyte concentration within the electrolyte gas sensor of the gas detection apparatus over the period of time and an average temperature in the surrounding environment over the period of time. The gas sensing apparatus can be configured to communicate the average ambient humidity value within the surrounding environment to a second electrochemical gas sensor or a second gas detection apparatus within the same surrounding environment.

Description

[0001] This application is a divisional application of the invention patent application with national application number 202010267142.X, the priority date of which is April 5, 2019, and the name of the invention is “Method and device for measuring humidity using an electrochemical gas sensor”. Technical Field

[0002] Various embodiments described herein generally relate to electrochemical gas sensors. In particular, various embodiments relate to electrolyte-based gas sensors configured to measure ambient humidity. Background Art

[0003] Industrial and commercial applications can use electrolyte-based electrochemical gas sensors to detect the presence of various gases. The ambient humidity present in the environment of conventional electrolyte-based electrochemical gas sensors can cause the sensor's electrolyte concentration to change due to water intake or loss from the surrounding environment. The resulting changes in electrolyte concentration affect sensor performance, often leading to inaccurate sensor measurements, reduced measurement sensitivity, and even sensor failure. Therefore, some electrolyte-based electrochemical gas sensors incorporate conventional humidity sensors to measure ambient humidity and compensate for the resulting changes in electrolyte concentration in order to properly calibrate the sensor's output. However, conventional humidity sensors are typically expensive and bulky, thereby increasing production costs and the footprint associated with the collective sensing components. Furthermore, compared to electrochemical gas sensors, existing humidity sensors used in such situations often produce unreliable readings and have relatively short lifespans (especially when exposed to humidity extremes).

[0004] Therefore, there is a need in the art for a reliable, long-lasting electrochemical gas sensor equipped with a solution for measuring humidity, characterized by low product cost and minimized sensor footprint. Summary of the Invention

[0005] Various embodiments are directed to methods and apparatus for reliably measuring humidity using electrolyte-based electrochemical gas sensors.

[0006] Various embodiments relate to a method for detecting gas using an electrochemical gas sensor and a gas detection device, the gas detection device comprising: a first electrochemical gas sensor configured to measure an electrolyte concentration within an electrolyte-based first electrochemical gas sensor; a temperature sensor configured to measure a temperature of an ambient environment surrounding the first electrolyte-based electrochemical gas sensor; and a controller in communication with the first electrolyte-based electrochemical gas sensor and the temperature sensor, wherein the controller can be configured to: (i) determine an average ambient temperature of the ambient environment during a first time period, (ii) determine an average rate of change of the electrolyte concentration within the first electrochemical gas sensor during the first time period, and (iii) determine an average humidity value of the ambient environment during the first time period based on the average ambient temperature and the average rate of change of the electrolyte concentration.

[0007] In various embodiments, the first electrochemical gas sensor can include a volume of an acid-based electrolyte. Furthermore, in various embodiments, the controller of the gas detection device can be configured to determine an average electrolyte vapor pressure over a period of time. In various embodiments, a temperature sensor can be integrated into the first electrochemical gas sensor. In various embodiments, the gas detection device can further include a gas detection device housing, wherein the gas detection device housing can include an outer housing portion and an inner housing portion, and wherein the first electrochemical gas sensor, the temperature sensor, and the controller can be enclosed within the inner housing portion.

[0008] In various embodiments, the average humidity value of the ambient environment during the first time period can be determined using a lookup table that correlates an average rate of change of the electrolyte concentration within the first electrochemical gas sensor during the first time period with corresponding humidity values ​​of the average ambient temperature and the average electrolyte vapor pressure within the first electrochemical gas sensor during the first time period. Furthermore, in various embodiments, the corresponding humidity value can define the average humidity value of the ambient environment during the first time period.

[0009] In various embodiments, the gas detection device may further include a second electrochemical gas sensor, wherein the second electrochemical gas sensor may be an electrolyte-based electrochemical gas sensor positioned within the ambient environment, and wherein the first electrochemical gas sensor may be configured to transmit an average humidity value of the ambient environment during the first time period to the second electrochemical gas sensor. In various embodiments, the second electrochemical gas sensor may include a volume of a non-acid-based electrolyte. Furthermore, in various embodiments, the second electrochemical gas sensor may be configured to apply an appropriate compensation factor to the output of the second electrochemical gas sensor based on the average humidity value of the ambient environment during the first time period. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and in which:

[0011] Figure 1 An exploded view of a gas sensor according to one embodiment is shown.

[0012] Figure 2 Schematically depicts a cross-sectional view of an electrochemical sensor according to one embodiment.

[0013] Figure 3 Shown is a graph of current versus potential according to one embodiment.

[0014] Figure 4A Shown is a graph of potential difference versus anode swing according to one embodiment.

[0015] Figure 4B Shown is a graph of potential difference versus anode swing corrected for anode swing according to one embodiment.

[0016] Figure 4C Shown is a graph of potential difference versus electrolyte concentration according to one embodiment.

[0017] Figure 5 An exemplary schematic block diagram is shown according to some exemplary embodiments described herein.

[0018] Figure 6 Shown is the flow of data between components according to some embodiments discussed herein.

[0019] Figure 7 A flow chart illustrating an exemplary method of measuring humidity using an electrochemical gas sensor according to some exemplary embodiments described herein is shown.

[0020] Figure 8 Exemplary graphical representations of data generated by a test configuration are shown according to various embodiments.

[0021] Figure 9 An exemplary graphical representation of data generated by a test configuration is shown in accordance with various embodiments.

[0022] Figure 10 An exemplary graphical representation of data generated by a test configuration is shown in accordance with various embodiments. DETAILED DESCRIPTION

[0023] The following description should be read with reference to the drawings, in which like reference numerals refer to like elements throughout the several views. The detailed description and drawings show several embodiments, which are intended to explain the disclosure. It should be understood that any numbered (e.g., first, second, etc.) and / or directional terms (e.g., front, back, top, bottom, side, etc.) used in connection with the disclosed features are relative terms for illustrative purposes and do not denote an absolute relationship among the related features.

[0024] It should be understood that, although the following illustrates exemplary implementations of one or more aspects, any number of techniques, whether currently known or not, can be used to implement the disclosed components, systems, and methods. The present disclosure should in no way be limited to the exemplary implementations, drawings, and techniques illustrated below, but can be modified in various ways within the scope of the appended claims and their equivalents. While dimensional values for various elements are disclosed, the drawings can not be drawn to scale.

[0025] The words “example” or “exemplary” are used herein to mean “serving as an example, instance, or illustration.” Any implementation described herein as “example” or “exemplary” is not necessarily to be construed as preferred or advantageous over other implementations.

[0026] SUMMARY

[0027] Methods and apparatuses are described herein for reliably measuring humidity using an electrolyte-based electrochemical gas sensor. An electrochemical gas sensor operating on an aqueous electrolyte, such as an acid-based electrolyte, can exhibit changes in electrolyte concentration due to water uptake or water loss from the surrounding environment. In particular, the concentration of the aqueous electrolyte in the electrolyte-based electrochemical gas sensor can change in response to the ambient humidity. It can therefore be desirable to characterize the average humidity of the sensor’s surrounding environment over a period of time in order to characterize changes in the electrolyte concentration of the sensor. The methods and apparatuses disclosed herein provide a solution for determining an average humidity value of the surrounding environment over a period of time using changes in the measured electrolyte concentration of the electrochemical gas sensor over the period of time and the measured average ambient temperature.

[0028] As described herein, the disclosed methods and apparatus can advantageously measure humidity based, in part, on the rate of change of electrolyte concentration within an electrochemical gas sensor. Thus, the disclosed methods and apparatus eliminate the need for a separate humidity sensor in order to appropriately compensate the readings of such a sensor based on the relative ambient humidity. Furthermore, the disclosed methods and apparatus can measure relative humidity with increased reliability and can result in increased sensor lifespan. Furthermore, by utilizing the existing hardware of an electrochemical gas sensor to determine humidity, the methods and apparatus described herein minimize the sensor's footprint and ultimately save production costs.

[0029] In one exemplary embodiment, a method for measuring humidity using an electrochemical gas sensor may further include using an average humidity value measured over a period of time to determine changes in electrolyte concentration for those types of electrochemical gas sensors where electrolyte concentration may be difficult to measure (e.g., those that do not utilize acid-based electrolytes). For example, it may be difficult (if not impossible) to measure changes in electrolyte concentration for an electrolyte-based electrochemical gas sensor using a non-acid-based electrolyte (e.g., a salt-based electrolyte, an ionic liquid-type electrolyte, an organic electrolyte). According to various embodiments, the average humidity value measured by the acid-based electrochemical gas sensor is then used to compensate the measurement value of the non-acid-based electrochemical gas sensor. In such embodiments, the overall accuracy of a system utilizing both acid-based and non-acid-based sensors can thereby be improved.

[0030] Device

[0031] In various embodiments, as disclosed herein, the gas detection device 100 may include an electrochemical gas sensor and a controller configured to measure average humidity over a period of time by measuring the electrolyte concentration within the electrochemical gas sensor and the temperature of the surrounding environment of the gas sensor over a given time period.

[0032] Figure 1 An exploded view of an exemplary electrochemical sensor 10 that can be used in accordance with various embodiments of the devices and methods described herein is shown. Microelectrodes 12, 14 are mounted in the sensor 10 at locations shown at separator 12-1 near a working electrode 20 (which may also be referred to as a sensing electrode) and at separator 14-1 between a reference electrode 22 and a counter electrode 24.

[0033] An electrolyte E is contained in the housing 26. The microelectrodes 12, 14 are immersed in the electrolyte E and are not in the direct path of the target gas.

[0034] The electrodes described above (such as 12, 14, 20, 22, and 24) are carried in a housing 26 along with an electrolyte E. As will be appreciated by those skilled in the art, the housing 26 may include a vent 30. The sensor 10 may be carried by a gas detector 10a in an outer housing 10b.

[0035] Electrical connection elements, indicated at 26-1, carried by the housing 26 are coupled to various electrodes in the housing 26. A power source 26-2, which may be implemented as a rechargeable battery, may be carried in the outer housing 10b to activate the gas detector 10a.

[0036] The external housing 10b may also carry control circuits 10c that are coupled to the connector element 26-1 to receive signals from and couple signals to the electrodes 20, 22, 24 in order to sense conditions in the sensor 10, or to control the operation of one or more electrodes 20, 22, 24 to perform the operational and diagnostic methods described herein.

[0037] Gas detector 10a can communicate with a remote monitoring system via interface circuitry 10d, which is coupled to control circuitry 10c via a medium M (which can be wired or wireless). Control circuitry 10c can be implemented at least in part with a programmable processor 10e that executes pre-stored control instructions 10f. In various embodiments, the processor can be configured to receive sensory readings measuring, for example, temperature, pressure, and electrolyte concentration.

[0038] An exemplary microelectrode can be made of PTFE-coated platinum wire (Advent Research Materials part number PT5431, comprising a 75µm diameter platinum wire with an approximately 18µm thick PTFE coating). In some embodiments, microelectrodes 12, 14 can comprise 50µm diameter platinum wire, approximately 6mm long, and immersed in electrolyte E. The wire can be cut with a scalpel to create a microdisk electrode inside sensor 10, and the PTFE insulation can be stripped from the end of the wire outside sensor 10 to allow electrical contact. The exposed tip of the wire can be pushed into the respective separator 12-1, 14-1 to prevent it from shorting to the adjacent electrodes 20, 22, 24. However, alternative methods include sandwiching the microelectrodes 12, 14 between two separators. Other configurations are within the spirit and scope of the present invention. For example, the microelectrodes may comprise uninsulated platinum wire and may operate as microcylindrical electrodes, or they may be formed by depositing platinum onto contact pins or pads by techniques such as electroplating or sputtering, or by printing a thick film of platinum onto a ceramic substrate. In some embodiments, each microelectrode 12, 14 may be used for independent diagnostic purposes, such as hydrogen peak reference, oxygen peak identification, etc. In various embodiments, exemplary microelectrodes may be fabricated by welding a piece of platinum wire, which may comprise, for example, a diameter between 25 μm and 75 μm (e.g., 50 μm) and a substantially small length (e.g., 1 mm), to the end of an electrochemically inert support wire composed of a suitable material (e.g., tantalum).

[0039] In some embodiments, scanning voltammetry can be performed on one or more of the microelectrodes 12, 14 to provide one or more diagnostic scans. Scanning voltammetry is an electrochemical technique that measures the current generated in an electrochemical cell when the voltage exceeds the voltage predicted by the Nernst equation. Voltammetry is performed by cycling the potential of the electrode and measuring the resulting current. In scanning voltammetry, the electrode potential can be linearly ramped relative to time in the cycling phase. In some embodiments, other waveforms can be used to complete scanning voltammetry. For example, the waveform can be a step-type staircase (staircase voltammetry) or a staircase (square wave voltammetry) with additional superimposed positive and negative steps. During each of these phases, the rate of change of voltage over time is referred to as the scan rate (V / s) of the experiment. The result of the scanning voltammetry scan on one or more of the microelectrodes 12, 14 can generate diagnostic information about the sensor 10.

[0040] Figure 2A cross-sectional view of an electrochemical sensor 210 is shown. The sensor 210 generally includes a housing 212 that defines a cavity or reservoir 214 designed to hold an electrolyte solution. A working electrode 224 can be positioned between an opening 228 and the reservoir 214. A counter electrode 216 and a reference electrode 220 can be positioned within the reservoir 214. When a gas reacts at the interface between the working electrode 224 and the electrolyte within the separator 222, a current and / or potential can be formed between the electrodes 216, 220 to provide an indication of the gas concentration. A reference electrode 220 can also be positioned within the reservoir 214 to provide a reference for the potential at the working electrode.

[0041] The housing 212 may contain an internal reservoir 214, and one or more openings 228 may be provided in the housing 212 to allow the gas to be detected to pass through the housing 212 and into the gas space 226. The housing 212 may generally be formed from any material that is substantially inert to the electrolyte and the gas being measured. In one embodiment, the housing 212 may be formed from a polymeric material, a metal, or a ceramic. For example, the housing may be formed from materials including, but not limited to, acrylonitrile butadiene styrene (ABS), polyphenylene oxide (PPO), polystyrene (PS), polypropylene (PP), polyethylene (PE) (e.g., high-density polyethylene (HDPE)), polyphenylene oxide (PPE), or any combination or blend thereof. One or more openings 228 may be formed through the housing 212 to allow ambient gas to enter the gas space 226 and / or to allow any gas generated within the housing 212 to escape. In one embodiment, the electrochemical sensor 210 may include at least one inlet opening 228 to allow ambient gas to enter the housing 212. The opening 228 may be provided in the cover (if present) and / or in the wall of the housing 212. In some embodiments, the openings 228 may include a diffusion barrier to restrict the flow of gas (e.g., carbon monoxide, hydrogen sulfide, oxygen, etc.) to the working electrode 224. The diffusion barrier may be formed by forming the openings 228 as capillaries, and / or a thin film or membrane may be used to control the mass flow rate through the one or more openings 228.

[0042] In one embodiment, the opening 228 can function as a capillary opening to provide rate-limited gas exchange between the interior and exterior of the housing 212. In one embodiment, the opening 228 can have a diameter that can be between about 200 μm and about 1.5 mm, wherein the opening 228 can be formed using a conventional drill bit to obtain a larger opening and a laser drill bit to obtain a smaller opening. The opening 228 can have a length between about 0.5 mm and about 5 mm, depending on the thickness of the cover or housing 212. In some embodiments, there can be two or more openings for the inlet gas. When a membrane is used to control the flow of gas into and / or out of the housing, the opening diameter can be larger than the sizes listed above because the membrane can contribute to and / or may be responsible for controlling the flow rate of gas into and out of the housing 212.

[0043] The reservoir 214 includes a counter electrode 216, a reference electrode 220, and a working electrode 224. In some embodiments, an electrolyte may be contained within the reservoir 214, and the counter electrode 216, the reference electrode 220, and the working electrode 224 may be electrically contacted by the electrolyte. In some embodiments, one or more porous separators 218, 222 or other porous structures may be used to keep the electrolyte in contact with the electrodes 216, 220, 224. The separators 218, 222 may include a porous member used as a core for holding and transporting the electrolyte between the reservoir 214 and the electrodes 216, 220, 224, while these separators are electrically insulating to prevent short circuits caused by direct contact between any two electrodes. One or more of the porous separators 218, 222 may extend into the reservoir 214 to provide a path for the electrolyte to reach the electrodes 216, 220, 224. In one embodiment, separator 218 may be disposed between counter electrode 216 and reference electrode 220 , and separator 222 may be disposed between reference electrode 220 and working electrode 224 .

[0044] One or more of the separators 218, 222 may include a non-woven porous material (e.g., a porous felt member), a woven porous material, a porous polymer (e.g., an open-cell foam, a solid porous plastic, etc.), etc., and is generally chemically inert with respect to the electrolyte and the materials forming the electrodes. In one embodiment, the separators 218, 222 may be formed from various materials that are substantially chemically inert with respect to the electrolyte, including but not limited to glass (e.g., a glass mat), a polymer (a plastic disk), a ceramic, etc.

[0045] The electrolyte may be any conventional aqueous acidic electrolyte such as sulfuric acid, phosphoric acid, or a neutral ionic solution such as a salt solution (e.g., a lithium salt such as lithium chloride, etc.), or any combination thereof. For example, the electrolyte may comprise sulfuric acid having a molar concentration between about 3M and about 12M. Since sulfuric acid is hygroscopic, the concentration may vary from about 10% by weight to about 70% by weight (1 mole to 11.5 moles) within an ambient relative humidity (RH) range of about 3% to about 95%. In one embodiment, the electrolyte may comprise phosphoric acid having a concentration in an aqueous solution between about 30% by weight and about 60% by weight H3PO4. For another example, the electrolyte may comprise a lithium chloride salt having about 30% by weight to about 60% by weight LiCl, the remainder being an aqueous solution. As another example, a proton-conducting ionic liquid may be used.

[0046] In some embodiments, the electrolyte can be in the form of a solid polymer electrolyte comprising an ion exchange membrane. In some embodiments, the electrolyte can be in the form of a free liquid, disposed in a matrix or slurry, such as glass fibers (e.g., separator 218, separator 222, etc.), or disposed in the form of a semi-solid or solid gel.

[0047] The working electrode 224 may be disposed within the housing 212. Gas entering the sensor 210 may contact one side of the working electrode 224 and pass through the working electrode 224 to reach the interface between the working electrode 224 and the electrolyte. The gas may then react to generate a current indicative of the gas concentration. As discussed herein, the working electrode 224 may include multiple layers. The base or substrate layer may include a hydrophobic material or a hydrophobically treated material. A catalytic material may be formed as an electrode on one side of the working electrode 224 and placed in contact with the electrolyte.

[0048] In one embodiment, the working electrode 224 may include a porous substrate or membrane as a base layer. The substrate is permeable to the gases of interest, which in some embodiments may include hydrogen sulfide, carbon monoxide, or oxygen. In one embodiment, the substrate may include carbon paper formed from carbon fibers or graphite fibers. In some embodiments, the substrate may be made conductive by adding a conductive material such as carbon. The use of carbon can provide a sufficient degree of conductivity to allow detection of the current generated by the reaction of the gas at the surface of the working electrode 224 with the electrolyte via leads coupled to the working electrode 224. Other conductive substrates may also be used, such as carbon felt, porous carbon sheets, and / or conductive polymers (such as polyacetylene), each of which can be made hydrophobic as described below. Alternatively, conductive leads may be coupled to the catalytic layer to electrically couple the catalytic material to an external circuit, as described in more detail herein. In one embodiment, the substrate may be about 5 mils to about 20 mils thick in some embodiments.

[0049] The porous substrate may be hydrophobic to prevent the electrolyte from passing through the working electrode 224. The substrate may be formed of a hydrophobic material or may be treated with a hydrophobic material. In one embodiment, the substrate may be made hydrophobic by impregnating the substrate with a hydrophobic material such as a fluorinated polymer (e.g., PTFE). In some embodiments, the substrate or membrane may comprise GEFC-IES (e.g., a copolymer of perfluorosulfonic acid and PTFE, commercially available from Golden Energy Fuel Cell Co., Ltd.), Nafion ® (Polytetrafluoroethylene and perfluoro-3,6-dioxa-4-methyl-7-octene-sulfonic acid copolymer, available from Dupont ™ ) commercially available) or pure or nearly pure polytetrafluoroethylene (PTFE). The impregnation process may include applying a solution or slurry containing the hydrophobic material to the substrate using a dip coating process, a coating process, or a rolling process. Alternatively, a dry composition such as a powder may be applied to the substrate. In some embodiments, an optional sintering process may be used to infuse the hydrophobic material into the substrate to produce a hydrophobic base layer of the working electrode 224, wherein both sides of the hydrophobic base layer are hydrophobic. The sintering process may cause the hydrophobic polymer to bond or fuse with the carbon of the substrate to firmly bond the hydrophobic material to the substrate.

[0050] The resulting substrate may comprise from about 30% to about 50% by weight of the hydrophobic polymer. The amount of hydrophobic material added to the substrate may affect the conductivity of the substrate, with conductivity tending to decrease as the amount of hydrophobic material increases. The amount of hydrophobic polymer used with the substrate may depend on the desired degree of hydrophobicity, the porosity to the target gas, and the resulting conductivity of the working electrode.

[0051] The catalytic layer can be formed by mixing the desired catalyst with a binder and depositing the mixture on the substrate material. The binder may include a perfluorinated ion electrolyte solution (e.g., GEFC-IES, Nafion ® etc.), hydrophobic materials (such as PTFE), mixtures thereof, etc. When used as a binder, GEFC-IES, Nafion ® The PTFE and / or PTFE can influence gas diffusion parameters while simultaneously loading the electrocatalyst and maximizing the interface between the catalyst, gas, and electrolyte where the electrochemical process occurs. Ethylene glycol or other similar chemicals can be used as a diluent to form a catalyst slurry, formulation, or catalyst system that can be printed onto a substrate by a printer.

[0052] The catalytic layer can be deposited onto the substrate by, for example, screen printing, filtering in selected areas from a suspension placed on the substrate, spraying, or any other method suitable for producing a patterned deposition of solid materials. Deposition can be of a single material or of more than one material sequentially deposited in layers, such as to vary the properties of the electrode material through its thickness or to add a second layer with increased conductivity above or below the layer that is the primary site of gas reaction. Once deposited, the printed element can be sintered at high temperature to form the electrode.

[0053] In the working electrode 224, the catalytic layer may comprise carbon (e.g., graphite) and / or one or more metals or metal oxides, such as copper, silver, gold, nickel, palladium, platinum, ruthenium, iridium and / or oxides of these metals. The catalyst used may be a pure metal powder, a metal powder mixed with carbon, or a metal powder supported on a conductive medium (such as carbon), or a combination of two or more metal powders as a blend or as an alloy. The materials used for each electrode may be the same or different. In one embodiment, the working electrode 224 comprises a platinum-ruthenium black (Pt-Ru black) electrode. The atomic ratio of Pt to Ru in the Pt-Ru black electrode may be in the range of about 1:1 to about 1:5, or about 1:2. The amount of catalytic material per square centimeter (cm2) of the working electrode 224 may be greater than or equal to 1:1. <2> ) The surface area load can be between about 0.1 mg / cm <2> and about 5mg / cm <2> Between, or between about 0.5mg / cm <2> and about 2 mg / cm <2> between, or about 1 mg / cm <2> .

[0054] The counter electrode 216 may be disposed within the housing 212. The counter electrode 216 may include a substrate or membrane having a catalytic material disposed thereon, such as a PTFE membrane, a GEFC-IES membrane, a Nafion ® Membranes, etc. In one embodiment, the catalytic material can be mixed and disposed on the membrane using any suitable process, such as roller coating, coating, screen printing, etc. to apply the catalytic material to the membrane, as described in more detail herein. The catalyst layer can then be bonded to the membrane by a sintering process as described herein.

[0055] In one embodiment, the catalytic material for the counter electrode may include a precious metal such as gold (Au), platinum (Pt), ruthenium (Ru), rhodium (Rh), iridium (Ir), their oxides, or any combination thereof. In one embodiment, the catalytic material includes a Pt-Ru mixture screen-printed on a membrane, wherein the membrane may be a GEFC-IES membrane. The catalyst loading of the counter electrode 216 may be within any range described herein for the working electrode 224. In one embodiment, the catalyst loading of the counter electrode 216 may be the same or substantially the same as the catalyst loading of the working electrode 224, and the catalyst loading may also be greater than or less than the catalyst loading of the working electrode 224. Similarly, the reference electrode 220 may be disposed within the housing 212. The reference electrode 220 may include a substrate or membrane having a catalytic material disposed thereon, such as a PTFE membrane, a GEFC-IES membrane, a Nafion membrane, or a similar membrane. ® Membranes, etc. In one embodiment, the catalytic material may be mixed with a hydrophobic material (such as PTFE, etc.) and disposed on a PTFE membrane. Any of the methods for forming a working electrode or a counter electrode may also be used to prepare the reference electrode 220. In one embodiment, the catalytic material used with the reference electrode 220 may include a precious metal such as gold (Au), platinum (Pt), ruthenium (Ru), rhodium (Rh), iridium (Ir), their oxides, or any combination thereof. In an embodiment, the catalytic material used to form the reference electrode 220 may include a Pt-Ru mixture screen-printed on a membrane, wherein the membrane may be a GEFC-IES membrane. The catalyst loading of the reference electrode 220 may be within any range described herein for the working electrode 224. In one embodiment, the catalyst loading of the reference electrode 220 may be the same or substantially the same as the catalyst loading of the working electrode 224, and the catalyst loading may also be greater than or less than the catalyst loading of the working electrode 224. Although in Figure 1 2 is shown with a reference electrode 220 , but some embodiments of the electrochemical sensor may not include a reference electrode 220 .

[0056] In order to detect the current and / or potential difference across the electrodes in response to the presence of the target gas, one or more leads or electrical contacts may be electrically coupled to the working electrode 224, the reference electrode 220, and / or the counter electrode 216. The leads contacting the working electrode 224 may contact either side of the working electrode 224, as the substrate comprises a conductive material. To avoid the corrosive effects of the electrolyte, the leads contacting the working electrode 224 may contact the side of the working electrode 224 that is not in contact with the electrolyte. The leads may similarly be electrically coupled to the counter electrode 216 and the reference electrode 220. The leads may be electrically coupled to external connection pins to provide an electrical connection to an external processing circuit. The external circuit may detect the current and / or potential difference between the electrodes and convert the current into a corresponding target gas concentration.

[0057] In some embodiments, the sensor 210 may include one or more diagnostic microelectrodes 232 and 234 (which may be similar to Figure 1 The diagnostic electrodes may be metal wires (e.g. Figure 2 ), where the exposed tip of the wire can be pushed into the separators 222, 218 to avoid shorting it to the adjacent electrode. However, an alternative approach includes sandwiching the microelectrodes 232, 234 between two separators. Other configurations are within the spirit and scope of the present invention. For example, the microelectrodes may include uninsulated platinum wire and may operate as microcylindrical electrodes, or they may be formed by depositing platinum onto contact pins or pads by techniques such as electroplating or sputtering, or by printing a thick film of platinum onto a ceramic substrate. In some embodiments, each microelectrode 232, 234 can be used for a separate diagnostic purpose, such as hydrogen peak reference, oxygen peak identification, etc. The microelectrodes may include platinum, gold, ruthenium, rhodium, iridium, palladium, rhenium, osmium, or alloys thereof with each other or with other metals (e.g., platinum / nickel alloys).

[0058] In use, the sensor 210 can detect the concentration of the target gas. In use, ambient gas can flow into the sensor 210 through the opening 228, which serves as the air inlet port of the sensor 210. The ambient gas may include a certain concentration of the target gas, which may include hydrogen sulfide, oxygen, and / or carbon monoxide. The gas may contact the working electrode 224 and pass through the pores of the porous substrate layer to reach the surface of the working electrode 224 treated with the catalyst layer. The electrolyte may contact the surface of the working electrode 224, and the target gas may react and cause an electrolysis current to be formed between the working electrode 224 and the counter electrode 216. The electrolysis current corresponds to the concentration of the target gas in the ambient gas. By measuring the current, the concentration of the target gas can be determined using, for example, an external detection circuit.

[0059] In some embodiments of the present disclosure, one or more elements of the sensor can be scanned using sweep voltammetry (as described above in Figure 1 and Figure 2 ) to observe the effect of changes in the concentration of the electrolyte (E above).

[0060] One or more electrodes can be used to scan an electrochemical sensor. In some embodiments, the scanning can be done on a microelectrode within the sensor. The scan can generate a graph containing a plurality of peaks resulting from adsorption, desorption, formation, and / or reduction of certain elements. The scan can be done at a plurality of electrolyte concentrations, where the graph for each concentration can be compared. In some embodiments, the graph can show one or more peaks consistent with each concentration, which can be considered reference peaks. Additionally, the graph can show one or more peaks that vary with concentration. The voltage difference between the concentration-dependent peaks and the reference peaks can provide a correlation of electrolyte concentration. The correlation can be approximately linear when the axes of the graph are electrolyte concentration and voltage difference between the two peaks.

[0061] Once the correlation is established, the electrolyte concentration of a similar electrochemical sensor can be determined by performing a voltammetry scan on the sensor and then identifying the relevant peaks of the correlation. Once the voltage difference between the peaks is identified, the electrolyte concentration can be determined. The determined electrolyte concentration can be used to correct the sensor readings, and / or to identify any other errors of the sensor.

[0062] In some embodiments, a diagnostic microelectrode can be used to perform the voltammetry scan. A benefit of using a microelectrode can be that it is less power intensive, requires less measurement time, suffers less measurement distortion due to ohmic losses in the electrolyte, and avoids interference with the main gas working electrode.

[0063] The present disclosure has been generally described, the following examples are given as specific embodiments of the present disclosure, and demonstrate the practice and advantages thereof. It should be understood that the examples are given by way of illustration and are not intended to limit the specification or claims in any way.

[0064] Figure 3 A staircase voltammogram of an exemplary electrode is shown. To investigate the effect of changes in electrolyte concentration in a sensor cell, a scan voltammetry can be performed in a series of H2SO4 solutions (0.6 M, 2.5 M, 5 M, 8 M, 10 M, and 12 M), and the results are shown in Figure 3 In other words, using the same electrode, the acid concentration is varied between 0.6 M and 12 M.

[0065] Figure 3 The staircase voltammogram shown in FIG. 2A shows a graph generated from an exemplary microelectrode, which includes a 50 pm diameter platinum wire of about 6 mm in length immersed in an electrolyte. The scan is done at 5 V / s, with a step of 2 mV, and the charge integration is 100%. The sensor is galvanostatically scanned between hydrogen (H2) and oxygen (O2) evolution 10 times to clean the electrode prior to the voltammetry scan. The wire microelectrode is driven against a conventional platinum reference electrode and counter electrode.

[0066] As Figure 3 shown in the middle, the hydrogen peaks (B, C, E, and F) occur at well-defined potentials and can thus be used as a standard reference, with peak (C) being the most well-defined. The peaks representing oxide formation (G) and reduction (A) appear to be electrolyte concentration dependent, with peak (G) not always being well-defined. However, peak (A) is always clear and easily detected, but its position varies with the anodic swing (H). Thus, to determine the correlation, the anodic swing (H) can be fixed with respect to the hydrogen peak (C), such that the voltage difference (i.e., V(A) - V(C)) is a measure of electrolyte concentration. In Figure 3 The tests shown in the middle indicate that the presence of oxygen does not interfere with the measurement.

[0067] Figure 4A The oxide reduction peak position is shown as a function of the anodic limit. The linear correlation is shown on the graph. To correct for the anodic limit, the slope of the linear correlation can be adjusted. As Figure 4B shown in the middle, a slope of approximately 0.2*x is applied to the data. Figure 4B The correction for the effect of the anodic limit is shown. In another embodiment, the effect of the anodic limit can be taken into account when determining the peak difference, where the anodic limit can be defined with respect to the hydrogen reference peak.

[0068] Figure 4C The corrected peak difference is shown as a function of electrolyte concentration. Figure 4C A strong correlation exists between the potential difference between the two peaks (oxide reduction and adsorbed hydrogen) and the concentration of the electrolyte. Thus, this measurement can therefore be used as an indicator of electrolyte concentration. Additionally, the potential appears to depend linearly on the electrolyte concentration over the entire environmental range of interest (0.6M - 12M).

[0069] In this case, temperature may have an effect on the electrolyte concentration measurement made by the diagnostic microelectrode. The effect may be small and can be easily compensated by using a low precision temperature sensor. As an example, the observed peak separation increases by about 1 mV / C, which may be equivalent to about 0.07 M / C. In some embodiments, voltammetry can be performed using square wave voltammetry (SWV). The use of SWV can improve the clarity of the hydrogen peak compared to traditional step voltammetry. In some embodiments, both techniques can be used. For example, SWV can be used to determine the hydrogen peak, and then subsequent step voltammetry can be used to determine the oxide reduction peak. In addition, square wave voltammetry allows for the detection of an additional peak formed by oxides (usually just a shoulder in voltammetry). This additional peak is also a function of electrolyte concentration and temperature, so it can be used to assist or replace the oxide reduction peak. One benefit of using the above method is that the position of the oxide formation peak (G) is not affected by the anodic limit because it is formed on the anodic scan, so it does not have to be Figure 4B A further benefit of using the oxide formation peak (G) is that it gives a measurement that is more sensitive to electrolyte concentration and less sensitive to temperature. By fitting the square wave voltammetry results to Figure 1 The following equation was obtained on the sensor of the shown design, with a sulfuric acid concentration range of 7M to 14M in the temperature range of 20°C to 50°C.

[0070] V(AC) = 552 + 0.582 × temperature + 10.44 × concentration

[0071] V(GC) = 852 + 0.102 × temperature + 17.59 × concentration

[0072] Where V(AC) is the potential difference between the oxide reduction peak and the hydrogen peak in millivolts, V(GC) is the potential difference between the oxide formation peak and the hydrogen peak in millivolts, temperature is in degrees Celsius, and concentration is in moles per liter. Using the formation peak allows for a more sensitive measurement of electrolyte concentration, with less need for temperature compensation. Alternatively, both equations can be solved simultaneously to allow determination of both concentration and temperature, avoiding the need for a separate temperature sensor.

[0073] Square-wave voltammetry adds additional parameters that can be adjusted to optimize the measurement. For example, changing the step height changes the intensity of the oxide peak but does not affect the hydrogen peak. Therefore, SWV can be used to optimize peaks for measurement or help distinguish peak types, simplifying detection methods.

[0074] An exemplary gas detection device 100 described herein, such as a controller 500, is shown in FIG. Figure 5 In. Figure 5As shown in FIG. 5, the controller 500 can include a temperature measurement circuit 501, and a pressure measurement circuit 503, a processing circuit 508, a voltage regulator 502, an input / output circuit 504, a power circuit 505, a memory 506, a communication circuit 507, a humidity measurement circuit 510, an electrolyte level monitoring circuit 509, an electrochemical gas monitoring circuit 511, and an electrochemical gas detection circuit 512.

[0075] Accordingly, as used herein with respect to the components of the gas detection device 100, the use of the term "circuitry" includes specific hardware configured to perform the functions associated with the various circuits described herein. Of course, while the term "circuitry" should be interpreted broadly to include hardware, in some embodiments, the circuitry can also include software for configuring the hardware. For example, in some embodiments, the "circuitry" can include processing circuitry, storage media, network interfaces, input-output devices, and other components. In some embodiments, other elements of the controller 500 can provide or supplement the functionality of particular circuitry. For example, the processing circuitry 508 can provide processing functionality, the memory 506 can provide storage functionality, and the communication circuitry 507 can provide network interface functionality, among other examples.

[0076] The temperature measurement circuit 501 includes hardware components designed or configured to receive, process, generate, and transmit data such as environmental temperature data. In various embodiments, the temperature measurement circuit 501 can be configured to measure the temperature of the ambient environment in which the gas detection device 100 is located. In various embodiments, the temperature measurement circuit 501 can be configured to measure the ambient temperature over one or more time intervals. Further, the temperature measurement circuit 501 can be configured to determine a temperature change or average temperature over one or more time intervals. In various embodiments, the temperature measurement circuit 501 can be positioned within or external to the electrochemical gas sensor housing, and can also be integrated into one or more components of the gas detection device 100 (e.g., the electrochemical gas sensor).

[0077] The pressure measurement circuit 503 includes hardware components designed or configured to receive, process, generate, and transmit data, such as electrolyte water vapor pressure data. In various embodiments, the pressure measurement circuit 503 can be configured to measure the vapor pressure of the electrolyte present in the electrochemical gas sensor. In various embodiments, the electrolyte water vapor pressure can be a function of one or more of the measured electrolyte concentration value of the electrochemical gas sensor, the measured ambient temperature, and the total volume of water present in the electrochemical gas sensor. In various embodiments, the pressure measurement circuit 503 can be configured to measure the electrolyte water vapor pressure over one or more time intervals. Furthermore, the pressure measurement circuit 503 can be configured to measure the change in electrolyte water vapor pressure or the average electrolyte water vapor pressure over one or more time intervals. In various embodiments, the pressure measurement circuit 503 can be located within or outside the electrochemical gas sensor housing and can also be integrated into one or more components of the gas detection device 100 (e.g., the electrochemical gas sensor).

[0078] In some embodiments, the controller 500 may include input-output circuitry 504, which may in turn communicate with processing circuitry 508 to provide output to a user and, in some embodiments, receive user-provided input such as commands. Figure 6As shown in FIG. 5, input-output circuitry 504 can include a user interface 190, such as a graphical user interface (GUI), and can include a display, which can include a web user interface, a GUI application, a mobile application, a client device, or any other suitable hardware or software. In some embodiments, input-output circuitry 504 can also include a keyboard, a mouse, a joystick, a display device, a display screen, a touch screen, a touch region, soft keys, a microphone, a speaker (e.g., a buzzer), a light emitting device (e.g., a red light emitting diode (LED), a green LED, a blue LED, a white LED, an infrared (IR) LED, an ultraviolet (UV) LED, or a combination thereof), or other input-output mechanisms. Processing circuitry 508, input-output circuitry 504 (which can utilize processing circuitry), or both, can be configured to control one or more functions of one or more user interface elements through computer-executable program code instructions (e.g., software, firmware) stored in non-transitory computer-readable storage medium (e.g., memory 506). Input-output circuitry 504 is optional, and in some embodiments, controller 500 can not include input-output circuitry. For example, where controller 500 does not directly interface with a user, controller 500 can generate user interface data for display by one or more other devices that directly interface with one or more users and transmit the generated user interface data to one or more of those devices. For example, controller 500, using user interface circuitry, can generate user interface data for display by one or more display devices and transmit the generated user interface data to those display devices.

[0079] In various embodiments, power circuitry 505 can be configured to receive power and power gas detection device 100. As a non-limiting example, power circuitry 505 can include one or more batteries, one or more capacitors, one or more constant power sources (e.g., a wall outlet), etc. In some embodiments, power circuitry 505 can include an external power source positioned external to device housing 110 and configured to deliver alternating current power or direct current power to gas detection device 100. Additionally, in some embodiments, as shown in FIG. 5, power circuitry 505 can include an internal power source, such as one or more batteries, positioned within device housing 110. Figure 5 In various embodiments, power circuitry 505 can be configured to receive power and power gas detection device 100. As a non-limiting example, power circuitry 505 can include one or more batteries, one or more capacitors, one or more constant power sources (e.g., a wall outlet), etc. In some embodiments, power circuitry 505 can include an external power source positioned external to device housing 110 and configured to deliver alternating current power or direct current power to gas detection device 100. Additionally, in some embodiments, as shown in FIG. 5, power circuitry 505 can include an internal power source, such as one or more batteries, positioned within device housing 110.

[0080] In some embodiments, the processing circuit 508 (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 506 via a bus for transferring information between components of the device. The memory 506 may be non-transitory and may include, for example, one or more volatile and / or non-volatile memories. For example, the memory 506 may be an electronic storage device (e.g., a computer-readable storage medium). In another example, the memory 506 may be a non-transitory computer-readable storage medium that stores computer-executable program code instructions that, when executed by a computing system, cause the computing system to perform the various operations described herein. The memory 506 may be configured to store information, data, content, signal applications, instructions (e.g., computer-executable program code instructions), etc., to enable the controller 500 to perform various functions according to the exemplary embodiments of the present disclosure. For example, memory 506 can be configured to store electrolyte content monitoring techniques; capacitance measurement techniques; impedance measurement techniques; monitored data; monitored data range; frequency range (e.g., bandgap filter); electrolyte content monitoring signals; temperature measurement signals, temperature measurement data; pressure measurement signals, pressure measurement data; water volume content data; hygrometry techniques; hygrometry lookup tables; hygrometry data; any other suitable data or data structures; or any combination thereof. It will be understood that memory 506 can be configured to store, in part or in whole, any electronic information, data, data structures, embodiments, examples, graphs, processes, operations, techniques, algorithms, instructions, systems, apparatuses, methods, or computer program products described herein, or any combination thereof. In various embodiments, the lookup table can be a data matrix defining a relationship between a rate of change of electrolyte concentration during a first time period and humidity values ​​corresponding to an ambient temperature and an electrolyte water vapor pressure. Furthermore, a lookup table as described herein can correlate an average rate of change of electrolyte concentration within a first electrochemical gas sensor during a first time period with humidity values ​​corresponding to an average ambient temperature and an average electrolyte water vapor pressure within the first electrochemical gas sensor during the first time period, wherein the corresponding humidity values ​​define an average humidity value of the surrounding environment during the first time period.

[0081] The processing circuitry 508 can be embodied in a variety of different ways and, for example, can include one or more processing devices configured for independent execution. Additionally or alternatively, the processing circuitry 508 can include one or more processors configured in tandem via a bus to enable independent execution of instructions, pipelining, multithreading, or a combination thereof. The use of the term "processing circuitry" can be understood to include a single-core processor, a multi-core processor, multiple processors within a device, a remote or "cloud" processor, or a combination thereof.

[0082] In example embodiments, processing circuitry 508 can be configured to execute instructions stored in memory 506 or otherwise accessible to processing circuitry 508. Alternatively, or additionally, processing circuitry 508 can be configured to execute hard coded functionality. Thus, whether configured by hardware or software methods, or by a combination thereof, processing circuitry 508 can represent an entity capable of performing operations according to embodiments of the present disclosure while configured accordingly. Alternatively, or additionally, processing circuitry 508 can be configured to

[0083] In various embodiments, processing circuitry 508 can also be configured to control potentiostat 502 to complete voltammetry scans of the electrochemical gas sensor as described above.

[0084] Communication circuitry 507 can allow any sensed results or readings (e.g., electrochemical gas monitoring circuit 511 output, temperature measurement circuit 501 output, pressure measurement circuit 503 output, humidity measurement circuit 510 results) communicated to processing circuitry 508 as described herein to be further communicated to an external source. Communication circuitry 507 can include, for example, a network interface for enabling communications with a wired or wireless communication network. For example, communication circuitry 507 can include one or more network interface cards, antennas, buses, switches, routers, modems, and supporting hardware and / or software, or any other devices suitable for enabling communications via a network. In some embodiments, the communication interface can include circuitry for interacting with the antenna(s) to cause transmission of signals via the antenna(s) or to process received signals from the antenna(s). The gas detection device 100 can use any of a variety of Internet, Ethernet, cellular, satellite or wireless technologies for transmitting or receiving these signals, such as IEEE 802.11, Code Division Multiple Access (CDMA), Global System for Mobile (GSM), Universal Mobile Telecommunications System (UMTS), Long Term Evolution (LTE), Bluetooth ® v1.0 to v5.0, Bluetooth Low Energy (BLE), infrared wireless (e.g., IrDA), Ultra-Wideband (UWB), inductive wireless transmission, Wi-Fi, near field communication (NFC), Worldwide Interoperability for Microwave Access (WiMAX), radio frequency (RF), RFID, or any other suitable technology.

[0085] In various embodiments, the processing circuit 508 may be configured to communicate with the humidity measurement circuit 510. The humidity measurement circuit 510 may include a hardware component that is designed or configured to receive, process, generate, and transmit data such as ambient humidity data. In various embodiments, the humidity measurement circuit 510 may be configured to measure the humidity of the surrounding environment in which the gas detection device 100 is located. In various embodiments, the ambient humidity may be a function of one or more of the rate of change of the electrolyte concentration in the electrochemical gas sensor, the measured ambient temperature, and the electrolyte water vapor pressure. In various embodiments, the humidity measurement circuit 501 may be configured to measure the ambient humidity over one or more time intervals. In addition, the humidity measurement circuit 510 may be configured to measure the average ambient humidity over one or more time intervals. In various embodiments, the humidity measurement circuit 510 can be configured to determine the average ambient humidity over a period of time by retrieving electrolyte concentration data defining the average rate of change of electrolyte concentration within the electrochemical gas sensor over the period of time and, based on data stored in a lookup table in the memory 504 that correlates the rate of change of electrolyte concentration with relative humidity values, determining a relative humidity value corresponding to the average rate of change of electrolyte concentration over the period of time (under the average ambient temperature measured by the temperature measurement circuit 501 and the average electrolyte water vapor pressure measured by the pressure measurement circuit 503). The humidity measurement circuit 510 can be configured to correlate the measured relative humidity value from the lookup table with the average ambient humidity over the period of time. In various embodiments, the humidity measurement circuit 501 can be configured to communicate with one or more of the various components of the controller 500.

[0086] A user interface circuit as described herein can include hardware components designed or configured to receive, process, generate, and transmit data such as user interface data. In some embodiments, a user interface circuit can be configured to generate user interface data indicative of a set of monitoring modes for a particular gas type or environment, an electrochemical gas monitoring signal, an RMS electrochemical gas monitoring signal, a predetermined electrochemical gas monitoring threshold (e.g., can be set by a user using input-output circuit 504 or a user device in communication with input-output circuit 504; can be set by accessing a table of predetermined electrochemical gas monitoring thresholds for various gas types), an electrochemical gas alarm signal, an electrolyte level monitoring signal, an RMS electrolyte level monitoring signal, an electrolyte level value (including but not limited to an electrolyte level percentage value), a low electrolyte alarm signal, a pressure value, an ambient temperature value, an ambient humidity value, and combinations thereof. In certain instances, user interface data can include a list of monitoring modes (e.g., a selectable drop-down list, an ordered grouping of selectable icons (e.g., clickable icons configured to be clicked by a mouse; virtual icons configured to be displayed on a touchscreen and pressed by a user’s finger), text-based prompts, voice-based prompts). For example, a user interface circuit can include hardware components designed or configured to generate user interface data based on any embodiment or combination of embodiments described with reference to the drawings included herein.

[0087] In some embodiments, a user interface circuit can be in communication with a display device (e.g., input-output circuit 504, a user device, or a display device communicatively coupled with a user device) and thus configured to transmit user interface data to the display device. For example, a user interface circuit can be configured to generate user interface data and transmit the generated user interface data to input-output circuit 504, and input-output circuit 504 can be configured to receive the user interface data and display the received user interface data on one or more display screens.

[0088] In some embodiments, each of the electrochemical gas monitoring circuit 511, the electrochemical gas detection circuit 512, the electrolyte content monitoring circuit 509, the user interface circuit, the temperature measurement circuit 501, the pressure measurement circuit 503, and the humidity measurement circuit 510 may include a separate processor, a specially configured field programmable gate array (FPGA), an application specific interface circuit (ASIC), or a cloud utility to perform the above functions. In some embodiments, the hardware components described above with reference to the electrochemical gas monitoring circuit 511, the electrochemical gas detection circuit 512, the electrolyte content monitoring circuit 509, the user interface circuit, the temperature measurement circuit 501, the pressure measurement circuit 503, and the humidity measurement circuit 510 may utilize, for example, the communication circuit 507 or any suitable wired or wireless communication path to communicate with the user device, each other, or with any other suitable circuit or device.

[0089] In some embodiments, one or more of the electrochemical gas monitoring circuit 511, the electrochemical gas detection circuit 512, the electrolyte level monitoring circuit 509, the user interface circuit, the temperature measurement circuit 501, the pressure measurement circuit 503, and the humidity measurement circuit 510 may be hosted locally by the controller 500. In some embodiments, one or more of the user interface circuit and the humidity measurement circuit 510 may be hosted remotely (e.g., via one or more cloud servers) and, therefore, need not physically reside on the controller 500. Thus, some or all of the functionality described herein may be provided by the remote circuits. For example, the controller 500 may access one or more of the remote circuits via any type of network connection that facilitates the transfer of data and electronic information between the controller 500 and the remote circuits. The controller 500 may then remotely communicate with one or more of the electrochemical gas monitoring circuit 511, the electrochemical gas detection circuit 512, the electrolyte level monitoring circuit 509, the user interface circuit, the temperature measurement circuit 501, the pressure measurement circuit 503, and the humidity measurement circuit 510.

[0090] As described above, and based on the present disclosure, it will be appreciated that the embodiments of the present disclosure may be configured as systems, devices, methods, mobile devices, back-end network devices, computer program products, other suitable devices, and combinations thereof. Thus, the embodiments may include various devices comprising complete hardware or any combination of software and hardware. In addition, the embodiments may take the form of a computer program product on at least one non-transitory computer-readable storage medium, the computer program product having computer-readable program instructions (e.g., computer software) embodied in the storage medium. Any suitable computer-readable storage medium may be utilized, including a non-transitory hard disk, CD-ROM, flash memory, optical storage device, or magnetic storage device. It should be understood that any computer program instructions and / or other types of code described herein may be loaded onto the circuits of a computer, processor, or other programmable device to produce a machine, such that the computer, processor, or other programmable circuit that executes the code on the machine forms a device for implementing various functions (including those described herein).

[0091] In some embodiments, the user device may be embodied by one or more computing devices or systems that may also include processing circuitry, memory, input-output circuitry, and communication circuitry. For example, the user device may be a laptop computer on which an application (e.g., a GUI application) is running or otherwise executed by processing circuitry. In yet another example, the user device may be a smartphone on which an application (e.g., a web browsing application) is running or otherwise executed by processing circuitry. As with the operations described in this disclosure, the functionality of these devices may utilize the same functionality as described above with reference to FIG. Figure 5 Similar components are described herein. For the sake of brevity, additional description of the mechanisms of these components has been omitted. These device elements, operating together, provide various computing systems with the functionality required to facilitate data communication with the example electrochemical gas sensors described herein.

[0092] As described above and as will be understood based on this disclosure, various embodiments may be configured in various forms, including those in which portions of the gas detection device 100 are remote from the Figure 6 The gas detection device 100 shown in FIG. Figure 6An exemplary data flow between various components according to an embodiment of a gas detection device 100 as discussed herein is shown. In various embodiments, the communication circuit 507 can be configured to enable wireless communication from the gas detection device 100 within an Internet of Things (IoT) network 600 to various wirelessly enabled devices (e.g., a user mobile device 601, a server 602, a computer 603, a second gas detection device 604). In an exemplary embodiment, the gas detection device 100 can be configured to transmit any of the aforementioned sensing results or readings (e.g., electrochemical gas monitoring circuit 511 output, temperature measurement circuit 501 output, pressure measurement circuit 503 output, humidity measurement circuit 510 results) transmitted to the processing circuit 508 to a second gas detection device 604 configured for wireless communication and located within substantially the same ambient environment. In various embodiments, the second gas detection device 604 can include one or more gas detection devices as disclosed herein. In various embodiments, the second gas device 604 can include an electrolyte-based electrochemical gas sensor, for which the electrolyte concentration may be difficult to determine. For example, the second gas detection device 604 may include an electrolyte-based electrochemical gas sensor using a non-acid-based electrolyte (such as a salt-based electrolyte, an ionic liquid-type electrolyte, or an organic electrolyte). In various embodiments, the gas detection device 100 may transmit an average humidity value within the surrounding environment measured by the humidity measurement circuit 510 of the gas detection device 100 to one or more second gas detection devices 604. In various embodiments, the one or more second gas detection devices 604 may be configured to respectively receive the average humidity value, thereby enabling compensation of the corresponding sensor output of the device.

[0093] How to use

[0094] Figure 7 A block diagram of an exemplary method 700 for measuring humidity using an electrochemical gas sensor is shown.

[0095] Method 700 begins at step 701, where the electrolyte concentration and average temperature are first measured. Specifically, as shown in step 701A, the electrolyte concentration of an electrochemical gas sensor within a gas detection device is first measured. The method for measuring the electrolyte concentration of an electrochemical gas sensor as disclosed herein, or any other suitable device for determining the electrolyte concentration of an electrochemical gas sensor, can be implemented. In various embodiments, the time at which the electrolyte concentration of the electrochemical gas sensor is measured can define the end of a first time interval.

[0096] As shown in step 701B, the average temperature of the surrounding environment of the exemplary gas detection device is measured during a first time period. In various embodiments, the average ambient temperature during the first time period can be measured using an electrochemical gas sensor or a temperature sensor and corresponding temperature measurement circuitry (e.g., temperature measurement circuitry 501).

[0097] Next, at step 702, a value associated with the electrolyte concentration of the electrochemical gas sensor at the beginning of a first time period is stored in a memory module (e.g., memory 504). In various embodiments, the stored electrolyte concentration value may include a value associated with the electrolyte concentration of the electrochemical gas sensor at the end of a period of time immediately preceding the first time period.

[0098] Next, at step 703, the average electrolyte water vapor pressure of the electrochemical gas sensor over the first time period is determined. In various embodiments, the electrolyte water vapor pressure may be a function of one or more of a measured electrolyte concentration value of the electrochemical gas sensor and a measured ambient temperature. In various embodiments, the average electrolyte water vapor pressure over the time period may be a function of a measured electrolyte concentration value measured by the electrochemical gas sensor at the end of the first time period (i.e., the value measured at step 701A), a stored value associated with the electrolyte concentration of the electrochemical gas sensor at the beginning of the first time period, and the measured average ambient temperature over the first time period. In various embodiments, the average electrolyte water vapor pressure of the electrochemical gas sensor over the first time period may be determined using a pressure measurement circuit (e.g., pressure measurement circuit 503).

[0099] Next, at step 704, an average rate of change of the electrolyte concentration within the electrochemical gas sensor during the first time period is determined. In various embodiments, the average rate of change of the electrolyte concentration within the electrochemical gas sensor during the first time period can be determined by dividing the difference between a stored value associated with the electrolyte concentration of the electrochemical gas sensor at the beginning of the first time period and the electrolyte concentration value measured by the electrochemical gas sensor at the end of the first time period (i.e., the value measured at step 701A) by the length of the first time period.

[0100] Next, at step 705, one or more lookup tables are generated that relate the rate of change of the electrolyte concentration within the electrochemical gas sensor to corresponding ambient humidity values ​​at various ambient temperatures and electrolyte water vapor pressure values, and are stored in a memory module (e.g., memory 504). In various embodiments, each lookup table may define a relationship between the rate of change of the electrolyte concentration within the electrochemical gas sensor and the corresponding humidity value for a given ambient temperature / electrolyte water vapor pressure combination.

[0101] Next, at step 706, a stored lookup table is used to determine the average humidity value of the surrounding environment within the first time period based on the average rate of change of the electrolyte concentration within the electrochemical gas sensor within the first time period. In various embodiments, an appropriate lookup table configuration may be generated and / or determined based on the average ambient temperature and average electrolyte water vapor pressure measured within the first time period. In various embodiments, the generated lookup table may indicate that the average rate of change of the measured electrolyte concentration within the electrochemical gas sensor within the first time period may correspond to a specific ambient humidity value. In various embodiments, the specific corresponding ambient humidity value may be determined as the average humidity value of the surrounding environment within the first time period.

[0102] Figure 8-10 Each shows a graphical representation of data collected during various experimental trials of embodiments of the claimed invention. Figure 8-10 Each graphically illustrates the relationship between relative humidity and the rate of change of electrolyte concentration within an exemplary electrolyte gas sensor. Figure 8-10 As shown in , relative humidity can be measured along the y-axis and the rate of change of electrolyte concentration is measured along the x-axis. In various embodiments, Figure 8-10 Data defined by one or more exemplary lookup tables as described herein may be illustrated graphically.

[0103] Figure 8 The data shown represent the behavior of a volume of acid-based electrolyte in an electrolyte-based electrochemical gas sensor over a period of time at a constant temperature of 20 degrees Celsius. The initial electrolyte concentration at the beginning of the period is 5 M. The relationship shown is defined by the formula y = -70.956x + 62.694, where R 2 The value is 0.9999.

[0104] Figure 9 The data shown represent the behavior of a volume of acid-based electrolyte in an electrolyte-based electrochemical gas sensor over a period of time at a constant temperature of 20 degrees Celsius. The initial electrolyte concentration at the beginning of the period is 5 M. The relationship shown is defined by the formula y = -37.403x + 62.968, where R 2 The value is 0.9996.

[0105] Figure 10 The data shown represent the behavior of a volume of acid-based electrolyte in an electrolyte-based electrochemical gas sensor over a period of time at a constant temperature of 10 degrees Celsius. The initial electrolyte concentration at the beginning of the period is 5 M. The relationship shown is defined by the formula y = -141.97x + 62.536, where R 2 The value is 1.

[0106] As can be understood from the figures and description provided above, the accuracy of the method for measuring the average humidity value in the ambient environment by an electrochemical gas sensor can vary proportionally with the ambient temperature. That is, as the temperature increases, the accuracy of the measured average humidity improves, and as the temperature decreases, the accuracy of the measured average humidity deteriorates. For example, using an embodiment of the method as described herein, in an ambient environment of 20 degrees Celsius, the average humidity value over a period of one week can be measured to an accuracy of less than 7%. In addition, in an ambient environment of 30 degrees Celsius, the average humidity value over a period of one week can be measured to an accuracy of less than 14%. Similarly, it should be understood that increasing the length of the time period for performing the above-mentioned measurements is understood to proportionally improve the accuracy of the measured average humidity. In various embodiments, exemplary time intervals for measurement may include between five minutes and one month (e.g., one week).

[0107] in conclusion

[0108] Numerous modifications and other embodiments will occur to those skilled in the art to which this disclosure pertains, having the benefit of the teachings presented in the foregoing description and the associated drawings. Therefore, it should be understood that this disclosure is not limited to the specific embodiments disclosed, and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. A gas detection device comprising: a first electrolyte-based electrochemical gas sensor configured to measure an electrolyte concentration within the first electrochemical gas sensor by performing a voltammetric sweep across electrodes of the first electrochemical gas sensor; a temperature sensor configured to measure a temperature of an ambient environment surrounding the first electrolyte-based electrochemical gas sensor; and The controller is configured to determine an average humidity value of the surrounding environment based on an average ambient temperature and an average rate of change of the electrolyte concentration measured during a first time period.

2. The apparatus of claim 1, wherein the first electrochemical gas sensor comprises a volume of an acid-based electrolyte. 3 . The apparatus of claim 1 , wherein the controller is further configured to determine an average electrolyte water vapor pressure over a period of time.

4. The device of claim 1 , further comprising a gas detection device housing, wherein the gas detection device housing comprises an outer housing portion and an inner housing portion, and wherein the first electrochemical gas sensor, the temperature sensor, and the controller are enclosed within the inner housing portion.

5. The apparatus of claim 1 , wherein the average humidity value of the ambient environment during the first time period is determined using a lookup table that correlates an average rate of change of the electrolyte concentration within the first electrochemical gas sensor during the first time period with corresponding humidity values ​​at an average ambient temperature during the first time period and an average electrolyte water vapor pressure within the first electrochemical gas sensor, wherein the corresponding humidity values ​​define the average humidity value of the ambient environment during the first time period.

6. The apparatus of claim 1 , further comprising a second electrochemical gas sensor, wherein the second electrochemical gas sensor is an electrolyte-based electrochemical gas sensor positioned within the ambient environment, and wherein the first electrochemical gas sensor is configured to transmit an average humidity value of the ambient environment during the first time period to the second electrochemical gas sensor.

7. The apparatus of claim 6, wherein the second electrochemical gas sensor comprises a volume of a non-acid based electrolyte. 8 . The apparatus of claim 7 , wherein the second electrochemical gas sensor is configured to apply an appropriate compensation factor to the output of the second electrochemical gas sensor based on an average humidity value of the ambient environment during the first time period.

9. The apparatus according to claim 1, further comprising a communication module for transmitting the calculated average humidity value to other devices in the Internet of Things network for displaying and / or processing the received value.

10. The device of claim 1, wherein the electrodes comprise diagnostic microelectrodes.

11. The apparatus of claim 1, wherein the electrolyte concentration is varied within a range including 0.6 M and 12 M to perform the voltammetry scan.

12. A method for determining ambient humidity, comprising: measuring a change in electrolyte concentration in a first electrochemical gas sensor based on an electrolyte, wherein the change in electrolyte concentration is measured based on a voltammetric scan of an electrode of the first electrochemical gas sensor; measuring the ambient temperature of the surrounding environment surrounding the first electrolyte-based electrochemical gas sensor using a temperature sensor; as well as An average humidity value of the ambient environment is determined using a controller based on an average ambient temperature of the ambient environment and an average rate of change of the electrolyte concentration measured during a first time period.

13. The method of claim 12, wherein the first electrochemical gas sensor comprises a volume of an acid-based electrolyte. The method of claim 12 , wherein the controller is further configured to determine an average electrolyte water vapor pressure over a period of time.

15. The method of claim 12, wherein the temperature sensor is integrated into the first electrochemical gas sensor.

16. The method of claim 15, further comprising providing a gas detection device housing, wherein the gas detection device housing comprises an outer housing portion and an inner housing portion, and wherein the first electrochemical gas sensor, the temperature sensor, and the controller are enclosed within the inner housing portion.

17. The method of claim 12, wherein the average humidity value of the ambient environment during the first time period is determined using a lookup table, the lookup table correlating an average rate of change of the electrolyte concentration within the first electrochemical gas sensor during the first time period with corresponding humidity values ​​at an average ambient temperature during the first time period and an average electrolyte water vapor pressure within the first electrochemical gas sensor, wherein the corresponding humidity values ​​define the average humidity value of the ambient environment during the first time period.

18. The method of claim 12, further comprising providing a second electrochemical gas sensor and transmitting the average humidity value of the ambient environment during the first time period from the first electrochemical gas sensor to the second electrochemical gas sensor, wherein the second electrochemical gas sensor is an electrolyte-based electrochemical gas sensor positioned within the ambient environment.

19. The method of claim 18, wherein the second electrochemical gas sensor comprises a volume of a non-acid based electrolyte.

20. The method of claim 19, further comprising applying an appropriate compensation factor to the output of the second electrochemical gas sensor based on an average humidity value of the ambient environment during the first time period.

21. The method of claim 12, wherein the electrode comprises a diagnostic microelectrode.

22. The method of claim 12, wherein the electrolyte concentration is varied within a range including 0.6 M and 12 M to perform the voltammetric scan.

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