Electrochemical gas sensor assembly

Abstract

The various example embodiments described herein relate to a sensor assembly. The sensor assembly includes a first sensor cap and a second sensor cap. The first sensor cap is disposed on a first end of the sensor assembly and the second sensor cap is disposed on a second end of the sensor assembly. The first sensor cap defines a first capillary and the second sensor cap defines a second capillary therethrough. The sensor assembly further includes a first sensing unit, a second sensing unit, and a filter. The first sensing unit and the second sensing unit are disposed between the first sensor cap and the second sensor cap. In some example embodiments, the filter is reactive to a target gas and thereby prevents the target gas from flowing into the sensor assembly through the second capillary.

Description

Technical Field

[0001] The present disclosure generally relates to electrochemical gas sensors, and more particularly to the structure and components of electrochemical gas sensors and associated systems and devices. Background Art

[0002] Gas monitoring systems are commonly installed in workplaces and other locations to monitor the concentration of various gases present in the working environment. Such gas monitoring systems are often referred to as gas analyzers, gas detectors, gas sensors, etc. One such type of gas sensor is an electrochemical gas sensor (EGS). Electrochemical gas sensors (EGS) can be used to detect various types of gases, such as oxygen and toxic gases, including but not limited to carbon monoxide (CO), sulfur dioxide (SO2), hydrogen sulfide (H2S), formaldehyde (CH2O), etc. Existing electrochemical gas sensors are often used to detect gases, but they are often prone to providing inaccurate sensor readings related to any changes in environmental parameters, such as the temperature and humidity to which the sensor assembly and its associated components are exposed. Therefore, there has been a long-standing industry desire for more robust electrochemical gas sensors, i.e., sensors that can avoid many of the deficiencies of existing electrochemical sensors. Summary of the Invention

[0003] Various example embodiments described herein relate to a sensor assembly (also referred to as an "EGS assembly"). The sensor assembly includes a first sensor cap and a second sensor cap, the first sensor cap being disposed on a first end of the sensor assembly and the second sensor cap being disposed on a second end of the sensor assembly. The first sensor cap defines a first capillary therethrough, and the second sensor cap defines a second capillary therethrough. The sensor assembly further includes a first sensing unit and a second sensing unit disposed between the first sensor cap and the second sensor cap.

[0004] In one exemplary embodiment, the first sensor cap is disposed on a first end of the EGS assembly. Further, the first sensor cap defines a first capillary. In some example embodiments, the second sensor cap is disposed on a second end of the EGS assembly and defines a second capillary therethrough. Additionally, the EGS assembly includes a sensing element positioned between the first sensor cap and the second sensor cap.

[0005] According to another example embodiment, the first sensing unit includes at least a sensing electrode, a reference electrode, and a counter electrode. The second sensing unit includes an auxiliary electrode. According to another exemplary embodiment, the sensing electrode can be positioned on a first end of the EGS assembly. Further, the auxiliary electrode can be positioned on a second end of the EGS assembly. The counter electrode and the reference electrode are positioned between the sensing electrode and the auxiliary electrode.

[0006] In some example embodiments, the sensor assembly further includes a filter. The filter is defined by a material reactive to the target gas. Further, the filter may be positioned on the second capillary to prevent the target gas from flowing into through the second capillary. In this regard, the channel defined by the first capillary allows the target gas to pass therethrough. However, the filter positioned on the second capillary prevents the gas from passing therethrough.

[0007] According to various embodiments described herein, the filter includes at least one of a membrane or a chemical substance. Further, in another exemplary embodiment, the membrane may be a porous PTFE membrane or a fiberglass membrane. According to one exemplary embodiment, the chemical substance corresponds to potassium permanganate that can filter the target gas or a mixture of the chemical substance and a PTFE porous membrane or PTFE powder. In this regard, in some examples, an activated carbon filter may be used as the membrane for filtering the target gas.

[0008] According to some exemplary embodiments, a printed circuit board (PCB) may be coupled to the EGS assembly. The printed circuit board may be configured to determine a first current and a second current. In the presence of at least one environmental parameter, the first current is determined based on a first reaction between the target gas and the first sensing unit. The second current is determined based on a second reaction at the second sensing unit. In this regard, the first current corresponds to the amount of the target gas at the first sensing unit and the second current corresponds to the magnitude of at least one environmental parameter at the second sensing unit.

[0009] According to some example embodiments, the printed circuit board may be further configured to determine a differential current. The differential current depends on the first current and the second current. To this end, the differential current may correspond to the amount of the noise level based on the magnitude of the at least one environmental parameter. In some examples, the at least one environmental parameter includes at least one of a temperature value or a humidity value. The temperature and humidity values correspond to the relative temperature value and humidity value caused within the EGS assembly due to environmental conditions.

[0010] According to another example embodiment, another sensor assembly is described. The sensor assembly includes a first sensing unit, a second sensing unit, a first sensor cover, and a second sensor cover. Further, the first sensor cover defines a first capillary, and the second sensor cover defines a second capillary. In some examples, the first capillary may be laminated with a chemical substance serving as a filter or a barrier for the target gas. The filter may be adapted to prevent the target gas from flowing into through the first capillary based on the reaction between the filter and the target gas. In another exemplary embodiment of the present invention, the filter may be adapted to convert the target gas from one form to another form.

[0011] In an exemplary embodiment of the present invention, the second capillary allows the target gas to flow therethrough. The target gas reaches the sensing electrode and a sensing current is generated based on the reaction of the target gas with the sensing electrode.

[0012] In another exemplary embodiment, the second sensing unit may be coupled to the first sensor cap and the first sensing unit may be coupled to the second sensor cap. According to an exemplary embodiment, the sensing electrode may be positioned at the first end of the sensor assembly and the auxiliary electrode may be positioned at the second end of the sensor assembly.

[0013] According to an exemplary embodiment, another sensor assembly is described. The sensor assembly includes a housing, a second sensor cap, a first sensing unit, a second sensing unit, and a filter. Further, the filter is defined by a material reactive to the target gas. The second sensor cap may be positioned at the second end of the housing. Further, the housing includes a first sensor cap. In some example embodiments, the first sensor cap may be positioned at the first end of the housing.

[0014] In addition, in some embodiments, the first sensing unit and the second sensing unit are positioned between the first sensor cap and the second sensor cap. In this regard, in some exemplary embodiments, the first sensor cap defines a first capillary and the second sensor cap defines a second capillary. The first capillary is configured to allow the target gas to pass therethrough. The target gas after passing through the first capillary reacts with the sensing electrode of the first sensing unit. The reaction between the target gas and the first sensing unit results in the generation of a sensing current. The sensing current corresponds to the amount of the target gas. However, the filter positioned in fluid communication with the second capillary prevents the target gas from flowing into the second capillary.

[0015] In some example embodiments, the first sensing unit includes a sensing electrode, a reference electrode, and a counter electrode, and the second sensing unit includes an auxiliary electrode. Further, in an exemplary embodiment, the sensing electrode may be coupled to the first capillary. The auxiliary electrode may be coupled to the second capillary within the housing. The reference electrode and the counter electrode may be positioned between the sensing electrode and the auxiliary electrode.

[0016] According to some example embodiments, the sensor assembly further includes a printed circuit board configured to determine a first current based on a first reaction in the presence of at least one environmental parameter. The printed circuit board is further configured to determine a second current based on a second reaction at the second sensing unit. The first current corresponds to the amount of the target gas at the first sensing unit, and the second current corresponds to the magnitude of the at least one environmental parameter.

[0017] In some example embodiments, the printed circuit board is further configured to determine a differential current based on a first current and a second current. The differential current corresponds to an amount of a noise level based on a magnitude of the at least one environmental parameter.

[0018] According to some example embodiments, a first dimension of a first capillary may be the same as a second dimension of a second capillary.

[0019] In some exemplary embodiments, a structure of a four-electrode EGS is described. The four-electrode EGS may be adapted to remove ambient influence. The auxiliary electrode may be designed to detect a current generated due to a change(s) in an environmental parameter.

[0020] In one of the exemplary embodiments, a sensing electrode and an auxiliary electrode are separately placed at each end of an EGS assembly (e.g., any sensor cartridge), where two diffusion capillaries are respectively located on top and bottom of the sensor. The sensing electrode is exposed to a target gas via a first capillary. In another embodiment, the auxiliary electrode is exposed to external environmental conditions through a second capillary. However, due to the presence of a filter on the second capillary, the target gas cannot pass through the second capillary. The sensing electrode and the auxiliary electrode are exposed to the same environmental conditions.

[0021] In one of the exemplary embodiments, the filter is defined by a material, a membrane, or a powder filter that is reactive to the target gas. Further, the filter is positioned on the second capillary. A membrane or a chemical powder or an activated carbon filter may be used to protect the auxiliary electrode from exposure to the target gas. This type of sensor may be more robust and durable while monitoring ambient influence and the target gas. Thus, the EGS assembly may more accurately respond to a change in gas concentration based on a change(s) in an environmental parameter.

[0022] The above summary is provided for the sole purpose of providing an overview of one or more of the exemplary embodiments described herein, to provide a basic understanding of some aspects of the present disclosure. Accordingly, it should be understood that the above embodiments are merely examples and should not be construed in any way as narrowing the scope or spirit of the present disclosure. It should be understood that, in addition to the embodiments summarized herein, the scope of the present disclosure also encompasses many potential embodiments, some of which are further explained in the detailed description and its accompanying drawings below. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The description of the illustrative embodiments may be read in conjunction with the accompanying drawings. It should be understood that, for simplicity and clarity of illustration, the elements illustrated in the drawings are not necessarily drawn to scale. For example, the dimensions of some elements are exaggerated relative to other elements. Embodiments incorporating the teachings of the present disclosure are shown and described with reference to the drawings presented herein, in which:

[0024] Figure 1 A perspective view of an electrochemical gas sensor in accordance with some example embodiments described herein is illustrated;

[0025] Figure 2 A cross-sectional view taken through the midpoint of the electrochemical gas sensor and extending through the printed circuit board in accordance with some example embodiments described herein is illustrated;

[0026] Figure 3 A block diagram schematically depicting various components of an electrochemical gas sensor in accordance with some example embodiments described herein is illustrated;

[0027] Figure 4A An exploded top view of an electrochemical gas sensor in accordance with some example embodiments described herein is depicted;

[0028] Figure 4B An exploded bottom view of an electrochemical gas sensor in accordance with some example embodiments described herein is depicted;

[0029] Figure 5 A cross-sectional view of an electrochemical gas sensor and operations performed by the electrochemical gas sensor in accordance with another embodiment described herein is schematically depicted. DETAILED DESCRIPTION

[0030] Some embodiments of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all, embodiments of the disclosure are shown. In fact, the disclosures 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 the specification, the same numerals refer to the same elements. The terminology used in this patent is not meant to be limiting, as the devices or portions thereof described herein may be attached or utilized in other orientations.

[0031] The phrases “in one embodiment,” “according to one embodiment,” “in some embodiments,” etc., generally mean that the particular feature, structure, or characteristic following the phrase may be included in at least one embodiment of the present disclosure and may be included in more than one embodiment of the present disclosure (importantly, such phrases do not necessarily refer to the same embodiment).

[0032] As used herein, the word “exemplary” means “serving as an example, instance, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0033] If the specification states that a component or feature “may”, “can”, “is capable of”, “should”, “will”, “preferably”, “possibly”, “usually”, “optionally”, “for example”, “frequently”, or “might” (or other such language) be included or have a characteristic, then the particular component or feature need not be included or have that characteristic. Such a component or feature may optionally be included in some embodiments, or may be excluded.

[0034] According to some example embodiments, an EGS component as described herein may include electrodes. The “electrodes” may include graphite and / or one or more metals such as copper, silver, gold, nickel, palladium, platinum, ruthenium, iridium, other suitable metals, oxides of these metals, or combinations thereof. The materials used for the respective electrodes may be the same or different. Additionally, a catalyst may be used with the electrodes to accelerate the rate of a chemical reaction. In this regard, the catalyst may include pure metal powders, metal powders combined with carbon, metal powders supported on a conductive medium (such as carbon), combinations of two or more metal powders as a mixture or alloy, or other suitable configurations.

[0035] The electrodes may include a reactive material suitable for implementing the desired reaction. For example, the electrodes may be formed from a mixture of conductive catalyst particles in a binder (such as polytetrafluoroethylene (PTFE)).

[0036] The “separator” as described herein may include non-woven porous materials (e.g., porous felt members), woven porous materials, porous polymers (e.g., open-cell foams, solid porous plastics, etc.), etc., and may be substantially chemically inert with respect to the electrolyte and the materials forming the electrodes. In one embodiment, the separator may be formed from various materials that are substantially chemically inert to the electrolyte, including but not limited to glass (e.g., glass mats), polymers (plastic disks), ceramics, etc.

[0037] Depending on the target gas of interest, the “electrolyte” as described herein may include any aqueous electrolyte, such as a solution of salts, acids, bases, etc. According to various example embodiments described herein, the electrolyte may include a hygroscopic acid for use in an oxygen sensor, such as sulfuric acid. Other target gases may use the same or different electrolyte compositions. In addition to water-based electrolytes, ionic liquid electrolytes may also be used for detecting certain gases.

[0038] Electrochemical gas sensors are typically used for sensing at ppm levels. Some example embodiments described herein relate to electrochemical gas sensors with increased sensitivity, which can be used for sensing at ppb levels. In some examples, three electrodes can be used in the gas sensor to detect a target gas (e.g., formaldehyde) in a home environment. Generally, in operation, the baseline of an electrochemical gas sensor is typically affected by ambient parameters (or meteorological parameters) such as humidity or temperature. Thus, in such cases, the output current of the electrochemical gas sensor changes rapidly with changes in humidity or temperature within the sensor assembly. Additionally, the effects of temperature and humidity persist for a long time (e.g., several hours). Accordingly, some of the electrochemical gas sensors described herein can include a fourth electrode (e.g., a reference electrode) to measure the effects due to humidity and / or temperature. To this end, the fourth electrode (also referred to as the reference electrode (AE)) is adapted to remove the ambient effects of the environmental parameters or improve sensor selectivity. In some examples, the reference electrode can generally be located below the sensing electrode (SE) having a diffusion capillary.

[0039] Generally, an electrochemical gas sensor (EGS) is used to detect a target gas in the gas concentration flowing into the electrochemical gas sensor. The target gas is detected based on a chemical reaction between the target gas and the sensing electrode at the sensing electrode. In this regard, as a result of the chemical reaction, a current is generated depending on the type and amount of the target gas present in the gas concentration. EGSs generally operate based on an "oxidation-reduction" reaction occurring inside the EGS, e.g., when the target gas diffuses inside the EGS assembly. In this regard, during the oxidation-reduction reaction inside the EGS, the metal cathode in the first part of the EGS can chemically reduce oxygen from the target gas while the balancing reaction oxidizes the anode in the second part of the EGS. In this sense, in the EGS, an ion-conductive electrolyte can be used to connect, operatively connect, fluidly connect, and / or chemically connect the cathode and the anode. In this regard, the current flow caused by the oxidation-reduction reaction at the metal cathode and anode provides a measure of the target gas concentration detected by the EGS.

[0040] To this end, typically, components of an EGS are often exposed to environmental parameters and / or conditions (e.g., differential pressure or temperature) that affect the operating performance of the EGS. For example, in some cases, the presence of environmental parameters such as differential pressure and humidity affects the measurement of the target gas by the EGS. In this regard, such parameters often cause the generation of noise signals and fluctuations in the signals sensed by the sensing electrodes of the EGS, which signals correspond to the detection of the target gas. Thus, the noise signals and fluctuations in the output current caused by the presence or change of environmental parameters result in a change in the actual current value, which would have been reported due to the presence of the target gas, thereby affecting the sensor output. Generally, in the operation of an EGS, the effects of such environmental parameters and conditions to which the components of the sensor assembly are exposed persist for a long time, and the EGS does not quickly return to its original state. Therefore, it is desirable to minimize the noise from the sensed signal values in order to determine whether the sensed signal accurately represents the concentration of the target gas in the gas concentration.

[0041] Various exemplary embodiments described herein relate to an Electrochemical Gas Sensor (EGS). The EGS described herein provides an improved sensor assembly. The improved sensor assembly can be used to accurately determine a target gas, independent of interference in the sensed output. The cause of the interference may be due to environmental parameters within the EGS assembly to which the components of the EGS are exposed, but is not limited to these parameters.

[0042] Further, according to some example embodiments, the environmental parameters include changes in temperature and humidity, but are not limited to these. Additionally, a change in temperature causes the equilibrium of the reaction to shift from a stable state to an unstable state. The shift in equilibrium depends on the temperature coefficient of the electrode. Further, the redox reaction is controlled by the viscosity of the electrolyte, and the viscosity is adapted to change based on the change in temperature. Additionally, the temperature or heat can be in any form (such as IR radiation), but is not limited to this. An increase in heat or temperature accelerates the rate of the redox reaction, and the sensed current fluctuates from the actual value.

[0043] Moreover, according to some example embodiments, the effect of humidity is also similar to the effect of temperature. The rate of the redox reaction increases with an increase in humidity due to an increase in the ion concentration. Humidity and heat levels simultaneously affect the current values at the sensing electrode and the auxiliary electrode.

[0044] Figure 1The perspective view of an electrochemistry gas sensor (EGS) 100 according to some exemplary embodiments described herein is illustrated. The EGS 100 shown herein represents an external structure defined by a sensor body 102 (which may also be interchangeably referred to as a sensor assembly throughout the following description for the sake of simplicity). Illustratively, the sensor body 102 may be defined between a first end 104 and a second end 106. In this regard, the first end 104 corresponds to an end that defines a top surface 108 of the sensor body 102. Similarly, the second end 106 corresponds to an end of the sensor body 102 that defines a bottom surface 110 of the sensor body 102.

[0045] The EGS 100 further includes a sensor cover 112 and a dust cover 114. According to some example embodiments described herein, the sensor cover 112 has a first surface and a second surface and defines a capillary (not shown) therethrough. In some example embodiments, the sensor cover 112 may have a shape such as, but not limited to, a cylindrical cap shape or a disc shape, which may be positioned on the top surface 108 including the second end 106 of the sensor body 102. Further, according to some example embodiments, the dust cover 114 may be positioned on the sensor cover 112. The positioning of the dust cover 114 on the sensor cover 112 prevents dust particles from flowing into the sensor assembly (i.e., the sensor body 102) through the dust cover 114.

[0046] According to some example embodiments, the EGS 100 further includes a printed circuit board (PCB) 116 that may be coupled to the sensor body 102. In addition to the above components, in some example embodiments, the EGS 100 may further include one or more sensing elements (e.g., sensing die) and filters, the details of which are Figures 2 to 5 described herein. According to various example embodiments, the EGS 100 may be used to sense a target gas from a gas concentration.

[0047] In some examples, the EGS 100 may be used in some industries: regardless of environmental fluctuations (such as temperature and humidity to which the sensor assembly is exposed), it is crucial to measure the target gas. To this end, according to various example embodiments described herein, the EGS 100 may be adapted to determine the target gas by removing the contribution of noise signals from the sensing signal. In this regard, the noise signal may be a signal that takes into account the noise caused by changes in environmental parameters experienced by the EGS 100 and that causes sensor reading errors.

[0048] Figure 2 The cross-sectional view of an electrochemistry gas sensor (EGS) 100 according to some example embodiments described herein is illustrated. Figure 2The cross-sectional view of the EGS 100 shown represents the internal structure and arrangement of the components of the EGS 100. In this regard, according to some example embodiments, the EGS 100 includes, starting from the top, a dust cover 202, which may have a disk shape and may be positioned on the sensor cover 204. The dust cover 202 may include a dust cap, a seal sleeve, or a cover surrounding the sensor cover 204. In some example embodiments, the dust cover 202 may be made of rubber, nylon, polyamide, or any other material. In this regard, in some example embodiments, the material of the dust cover 202 may be selected from a permeable membrane or a semi-permeable membrane, which prevents dust particles from passing through but allows the target gas to pass through it and enter the sensor assembly.

[0049] In addition, in some example embodiments, the EGS 100 further includes a first sensing unit 212. Illustratively, the first sensing unit 212 is fluidly coupled to the sensor cover 204. In some example embodiments, the sensor cover 204 has a top surface and a bottom surface. The sensor cover 204 may further define a capillary 206 therethrough between the top surface and the bottom surface. Further, in some example embodiments, the capillary 206 extends between the first sensing unit 212 and the sensor body 102.

[0050] In some example embodiments, the first sensing unit 212 includes a sensing electrode 216, a reference electrode 220, and a counter electrode 222. In some example embodiments, the sensing electrode 216, the reference electrode 220, and the counter electrode 222 may be any solid electrical conductors adapted to carry current to a non-metallic solid, liquid, gas, plasma, or vacuum, but are not limited to these.

[0051] According to some example embodiments, the EGS 100 may include a sensing unit in two halves, wherein a pair of electrodes including the sensing electrode 216 and the reference electrode 220 defines the first half of the EGS 100, and another pair of electrodes including the counter electrode 222 and the reference electrode 220 defines the second half of the EGS 100. In this regard, the sensing electrode 216 provides a current generated due to a redox reaction at the sensing electrode 216. Further, in such an example, depending on the type of the target gas, the sensing electrode 216 and the counter electrode 222 may be used as the anode terminal or the cathode terminal, respectively.

[0052] As shown, the EGS 100 includes one or more separators (e.g., separator 226), which may be positioned between the electrodes to separate the sensing electrode 216, the reference electrode 220, and the counter electrode 222. In this regard, in one exemplary embodiment, the separator 226 may include a hole whose size can be designed to receive the first sensing unit 212. Further, in some example embodiments, the separator 226 may be operable to isolate the sensing electrode 216 from components located below the separator 226 in the EGS 100 assembly.

[0053] In some embodiments, the EGS 100 may further include one or more separators 226. The size of the separator 226 can be designed and configured to provide a cross - over path to the sensing electrode 216, the reference electrode 220, and the counter electrode 222 inside the EGS 100. In this regard, the separator 226 may also provide an ion path for electro - chemical pumping occurring inside the EGS 100.

[0054] As shown, the EGS 100 further includes a second sensing unit 208. Further, in some example embodiments, the second sensing unit 208 may be fluidly coupled to the sensor cover 112.

[0055] In another exemplary embodiment, the second sensing unit 208 may include an auxiliary electrode 218. In this regard, as shown, in some example embodiments, the first surface of the auxiliary electrode 218 may be coupled to the first surface of the sensor cover 112. Further, the second surface of the auxiliary electrode 218 may be immersed in the electrolyte. According to some example embodiments described herein, the physical and chemical properties of the auxiliary electrode 218 may be similar to those of the sensing electrode 216. Further, in one exemplary embodiment, the sensitivity of the auxiliary electrode 218 may be increased by using a catalyst layer on the auxiliary electrode 218 that is reactive to humidity and temperature changes.

[0056] In some example embodiments, the sensor cover 112 has a top surface and a bottom surface that define a capillary 210 therethrough. In this regard, the bottom surface of the sensor cover 112 is positioned on the first sensing unit 212, and the top surface of the sensor cover 112 is coupled to the filter 214. Further, the capillary 206 extends between the outer surface of the sensor body 102 and the first sensing unit 212. In a similar manner, the capillary 210 extends between the filter 214 and the second sensing unit 208. According to various exemplary embodiments described herein, the capillary 206 can be used as a gas inlet such that an air mixture including the target gas can flow into the EGS 100 via the capillary 206.

[0057] In some example embodiments, the filter 214 includes a material that is reactive with the target gas. The filter 214 is adapted to prevent the target gas from entering through the second capillary 210.

[0058] In another exemplary embodiment, the EGS 100 further includes a printed circuit board (PCB) 116, a core 224, and wires (not explicitly shown). Further, the sensor assembly of the EGS 100 can be further connected to the substrate of the PCB 116.

[0059] According to various example embodiments described herein, the target gas can flow through the first capillary 206 and reach the first sensing unit 212. At the first sensing unit 212, the target gas reacts with the sensing electrode 216 in the presence of various environmental parameters. The environmental parameters include, for example, temperature and humidity, but are not limited to these. The environmental parameters can include the relative temperature (i.e., heat level) and relative humidity value present near the EGS 100.

[0060] In some embodiments, the core 224 can be adapted to draw electrolyte through the stack of various components of the EGS 100 by capillary action as needed. In this regard, the core 224 can capture electrolyte from the main body cavity of the EGS 100 to maintain the liquid level across at least a portion of the stack of components of the EGS 100. Further, the core 224 can provide an ionic path for electrochemical pumping that occurs inside the EGS 100. The core 224 can also provide a wetting interface for the counter electrode 222 and the auxiliary electrode 218, and can prevent or partially prevent the target gas from passing therethrough.

[0061] Figure 3 Schematically depicts a block diagram of the various components of a system representing an electrochemical gas sensor (EGS) 300 (e.g., such as Figure 1 and Figure 2 the EGS 100 described respectively). Illustratively, the EGS 300 can include components such as, but not limited to, a first sensing electrode 216, a reference electrode 220, a counter electrode 222, an auxiliary electrode 218, a first sensor cap 204, a sensor cap 112, a PCB 116, a first capillary 206, a second capillary 210, and a filter 214. According to some exemplary embodiments, the EGS 300 is operable to detect a target gas based on an electrochemical reaction at the sensing electrode 216 of the EGS 300.

[0062] According to some exemplary embodiments described herein, the sensing electrode 216 may correspond to an electrode where at least a part of a "redox reaction" occurs when the target gas diffuses into the EGSs 100, 300. According to some embodiments, the redox reaction described herein may correspond to an electrochemical reaction involving a reduction reaction at the sensing electrode 216 and a balancing oxidation reaction at the counter electrode 222. In some embodiments, the counter electrode 222 may correspond to an electrode through which current flows when a reaction occurs at the sensing electrode 216. Additionally, the auxiliary electrode 218 may correspond to an electrode where at least a part of the redox reaction occurs in the absence of the target gas. In some examples, the current generated at the auxiliary electrode 218 may correspond to the drift of environmental parameters such as relative temperature and relative humidity levels.

[0063] In this regard, according to various exemplary embodiments, to balance the reaction at the sensing electrode 216, a reverse reaction occurs at the counter electrode 222, and vice versa. For example, in an exemplary scenario, if oxidation occurs at the sensing electrode 216, a reduction reaction occurs at the counter electrode 222. In some examples, the reference electrode 220 may correspond to an electrode having a stable electrode potential. In this regard, the reference electrode 220 may provide a measurement of the potential at the sensing electrode 216 without passing current through the reference electrode 220.

[0064] Furthermore, the reference electrode 220 may be configured to provide a stable reference potential required for the electrochemical reactions that may occur inside the EGSs 100, 300 during the operation of the EGSs 100, 300. In this regard, the reaction at the sensing electrode 216 relative to the reference electrode 220 and the counter electrode 222 results in a sensing current. The sensing current is caused by the presence of the target gas at the first sensing unit 212. Furthermore, the sensing current deviates due to the drift of environmental parameters (e.g., at least temperature and humidity).

[0065] In one exemplary embodiment, the auxiliary electrode 218 is adapted to determine an auxiliary current in the absence of the target gas. The auxiliary current depends on the amount of change in environmental parameters. The auxiliary current is determined to eliminate the contribution of the noise signal from the sensed signal. The noise signal depends on the fluctuations of environmental parameters such as temperature or humidity.

[0066] In an exemplary embodiment, the first capillary 206 and the second capillary 210 have the same dimensions and are subject to the same environmental conditions. The first capillary 206 and the second capillary 210 having the same dimensions are adapted to be exposed to similar environmental conditions. Further, the first capillary 206 allows gas to pass therethrough, and the filter 214 on the second capillary 210 prevents the target gas from passing therethrough. The sensed current at the first sensing unit 212 corresponds to the target gas and the environmental conditions / parameters. Further, the auxiliary current at the auxiliary electrode 218 is not affected by the target gas.

[0067] According to various example embodiments described herein, the PCB 116 may be configured to measure a first current based on the reaction of the target gas at the sensing electrode 216. The PCB 116 is further configured to determine a second current based on the reaction caused by the change in the environmental parameter at the auxiliary electrode 218.

[0068] In an exemplary embodiment, the circuit is directly connected to the EGS 100, 300 or to the PCB 116 and is configured to determine a differential current based on the sensed current and the auxiliary current. In an exemplary embodiment, the differential current results in subtracting the auxiliary current from the sensed current, or in other words, subtracting the noise or error signal caused by the environmental parameter. In an exemplary embodiment, the sensitivity and signal-to-noise ratio of the EGS 100, 300 may be improved based on the determination of the sensed current and the auxiliary current. In some embodiments, the differential current corresponds to the amount of the noise level based on the magnitude of the at least one environmental parameter. The at least one environmental parameter includes at least one of a temperature value or a humidity value within the sensor assembly.

[0069] In some embodiments, the PCB 116 may be further configured to provide, for example, a digitized output of the EGS 100, 300 to a processor, a computing device, a display device, or any other suitable instrument or device for further processing or analysis. In this regard, the digitized output may be related to the target gas monitored by the EGS 100, 300. In some embodiments, the digitized output may include a signal or other form of transmission indicating the concentration of the monitored target gas. In some embodiments, the digitized output may include a signal or signals or other form of transmission indicating the change in the concentration of the monitored target gas over time. In some embodiments, the digitized output may be a bursty or intermittent stream of batch-wise target gas concentration values over time, or a steady stream of target gas concentration values in real time or near real time.

[0070] In some embodiments, the signal or other transmission may include a signal or other transmission indicating current or potential between or within the first sensing units 212. In this regard, due to the redox reactions occurring at one or more electrodes of the EGSs 100, 300, current may flow, for example, between one or more electrodes (not shown). The redox reactions are caused by the entry of the target gas into the interior of the EGSs 100, 300. In some embodiments, the PCB 116 may include circuitry for measuring the current on the EGSs 100, 300 and controlling the bias. Additionally or alternatively, the PCB 116 may include processing circuitry configured to determine the sensed current due to the presence of the target gas at the sensing electrode 216. The processing circuitry is further configured to determine the auxiliary current due to drift of environmental parameters such as temperature and / or humidity.

[0071] According to one exemplary embodiment, the first sensor cap 204 may define a first capillary 206 therethrough, and the sensor cap 112 may define a second capillary 210 therethrough. Further, as shown, the filter 214 may be positioned on the second capillary 210. The filter 214 is reactive to the target gas and prevents the target gas from passing therethrough.

[0072] Additionally and / or alternatively, in some example embodiments, the EGSs 100, 300 may include a dust cap 114, a dust cap 202, one or more separators 226, a core 224, and other components not illustrated herein Figure 3 herein.

[0073] In some embodiments, the EGSs 100, 300 may further include a catalyst (not shown) that may be used in addition to the sensing electrode 216. In this regard, in some examples, the catalyst may be laminated on the sensing electrode 216 to increase the sensitivity of the sensing electrode 216. In other words, the catalyst may help to increase the reaction rate between the target gas and the sensing electrode 216. According to some example embodiments, the type of catalyst that may be used in the EGSs 100, 300 and the sensing electrode 216 may depend on the target gas to be detected and measured by the EGSs 100, 300. In this regard, in some examples, a catalyst such as Pt, Ag, Au, Ru may be used depending on the type of target gas to be measured. For example, in one exemplary embodiment, when the target gas is CO, Pt may be used as the catalyst together with the sensing electrode 216. For the purpose of brevity, throughout the specification, the sensing electrode 216 may also be interchangeably referred to as the working electrode hereinafter.

[0074] Figure 4A and Figure 4BSchematically depicts an exploded top view 400 of an electrochemical gas sensor (EGS) 100 and an exploded bottom view 450 of the electrochemical gas sensor in accordance with some example embodiments described herein.

[0075] Illustratively, the exploded top view 400 of the EGS 100 depicts the various components of the EGS 100 and the positioning of the components. For example, the exploded top view 400 illustrates a dust cover 202 mounted on a first side of the sensor cap 204. The sensor cap 204 is mounted on a first side of the sensing electrode 216. Additionally, the sensing electrode 216 is coupled to a reference electrode 220 and a counter electrode 222. The sensing electrode 216 and the reference electrode 220 are separated by a separator 226. According to various exemplary embodiments, a first surface of the auxiliary electrode 218 is mounted on a first surface of the sensor cap 112. Further, a second surface of the auxiliary electrode 218 is immersed in the electrolyte. A filter 214 is placed on a second surface of the sensor cap 112. For example, when assembling the various components of the EGS, the various components of the EGS 100 may be adapted to engage or couple with each other to form a sensor assembly 100, as described below. In some embodiments, starting from the lower end, the sensor body 102 includes a PCB 116.

[0076] According to an exemplary embodiment described herein, the size of the sensing electrode 216 may be designed and configured to provide a medium for an electrochemical reaction of a target gas, which may diffuse into the interior of the EGS 100 through a first capillary 206 of the sensor cap 204. In this regard, in some example embodiments, the sensing electrode 216 may include or be made of a material that provides sufficient activity for reducing the target gas, and the target gas may contact the surface of an electrocatalyst present on the sensing electrode 216.

[0077] According to various example embodiments described herein, on a top surface 108 of the sensor body 102, the auxiliary electrode 218, the core 224, the counter electrode 222, the reference electrode 220, and the sensor cap 204 are stacked on top of each other. The sensing electrode 216 is adapted to generate a first current due to a first chemical reaction at the sensing electrode 216. Similarly, a second sensing unit (i.e., the auxiliary electrode 218) is adapted to generate a second current due to a second chemical reaction at the auxiliary electrode 218.

[0078] According to various example embodiments described herein, from Figure 4BStarting at the top of the exploded perspective view 450, EGS 100 also includes a filter 214, a sensor cover 112, and a sensing electrode 216. The filter 214 is mounted on a cavity defined by the sensor cover 112. The filter 214 is adapted to cover the capillary to prevent gas from entering therein. In some embodiments, EGS 100 may not include a PCB 116, but rather EGS 100 may be operatively coupled to an external PCB 116 or other such device such that measurement results and / or signals indicating measurement results completed by EGS 100 can be transmitted, stored, and / or displayed on a display device (not shown).

[0079] According to various example embodiments described herein, a PCB 116 according to various example embodiments described herein may be adapted to connect EGS 100 to an external circuit (not shown). In some embodiments, EGS 100 may include internal sensor pads (not shown) configured to be coupled to one or more sensor pads (not shown) of an external circuit in order to couple EGS 100 and an external circuit that may be external to EGS 100.

[0080] In some embodiments, EGSs 100, 300 may include one or more current collectors 402 that may be connected to a first sensing unit 208 and a second sensing unit 212 and a PCB 116, respectively, as Figure 4A shown. In this regard, in some examples, the one or more current collectors 402 may be adapted to provide electrical connections between one or more electrodes of EGSs 100, 300 and further provide electrical connections to one or more external contact pads on the PCB 116. For example, in some embodiments, one or more current collectors 402 may form one or more electrical connections with various components (including but not limited to the sensing electrode 216) via a separator 226, a reference electrode 220, a counter electrode 222, and an auxiliary electrode 218.

[0081] Figure 5 A cross-sectional view of an electrochemical gas sensor according to another embodiment described herein and operations performed by the electrochemical gas sensor (e.g., EGS 100) are schematically depicted. Figure 5 The structural arrangement of the EGS shown is similar to that of the EGSs 100, 300 shown in Figure 1 to FIG. 4. Further, as Figure 5 shown, the EGS includes the same as Figure 1An electrolyte 504 equivalent to the illustrated sensor body 102. Further, the dust caps 114 and 202 are adapted to prevent dust particles from passing therethrough. The filter 214 may be configured to prevent the target gas from flowing into the capillary 210 based on a chemical reaction between the filter 214 and the target gas. In an exemplary embodiment of the present invention, the filter 214 includes at least one of a membrane, a chemical substance, a mixture of a chemical substance and glass fibers, or a mixture of a chemical substance and PTFE powder. Additionally, the membrane includes an activated carbon filter, and the chemical substance includes potassium permanganate to absorb volatile organic compounds (VOCs) and formaldehyde content present in the target gas. The filter 214 prevents the target gas from entering due to the reaction between the target gas and the filter 214.

[0082] In an exemplary embodiment of the present invention, the first capillary 206 may be in fluid communication with the electrodes of the electrochemical cell of the EGS 100. The first capillary 206 may be operable to facilitate the flow of the target gas into the EGS 100. The gas inlet provided by the first capillary 206 may extend through a portion of the housing of the EGS 100. During operation of the EGS 100, the target gas may be delivered into the EGS 100 or the target gas may diffuse within the EGS 100 for the purpose of gas concentration measurement and / or monitoring.

[0083] In some embodiments, the electrochemical cell may be configured such that the sensing electrode 216 and the counter electrode 222 of the first sensing unit 212 together with the core 224 form a circuit, whereby ions may be transmitted between the sensing electrode 216 and the counter electrode 216 via the core 224. Electrons are transmitted in opposite directions between the counter electrode 222 and the sensing electrode 216, thereby generating a measurable current referred to as the sensing current.

[0084] In some embodiments, the sensing electrode 216 may be operably coupled, ionically coupled, electrically coupled, and / or fluidly coupled to the counter electrode 222, for example, via the core 224. The EGS 100 may optionally include a reference electrode (not shown). According to various exemplary embodiments described herein, the sensing electrode 216 may also be referred to as a "working electrode", a "first electrode", or a "consuming electrode", and generally refers to an electrode configured to be exposed to or consume at least a portion of the target gas during the concentration measurement of the target gas.

[0085] According to various exemplary embodiments, the EGS 100 or its components may be operable to monitor the concentration of a target gas (e.g., oxygen or carbon monoxide) based on a redox reaction that occurs when the target gas diffuses inside the EGS 100. In this sense, an electrochemical cell including the sensing electrode 216 may consume the target gas and transmit ions through the core 224 to the counter electrode 222, and the counter electrode 222 may generate the target gas, such that the measurement of the concentration of the target gas may be achieved by measuring the current flow or potential difference between the sensing electrode 216 and the counter electrode 222, which may be generated due to an electrochemical reaction inside the electrochemical cell.

[0086] In some embodiments, the EGS 100 may optionally include a printed circuit board (PCB) 116 that includes processing circuitry that may be configured to receive a digitized output indicative of a value corresponding to a current or voltage generated inside the electrochemical cell of the EGS 100. In this regard, according to various example embodiments described herein, the processing circuitry may process such values to determine the concentration of the target gas. In another example embodiment, the PCB 116 and the processing circuitry may be located outside the EGS 100.

[0087] In this regard, in some examples, one or more electrical contacts of the EGS 100 may be connected to the externally located PCB 116 and associated processing circuitry. In some embodiments, the PCB 116 and the processing circuitry may be located in a remote device that may be connected to the EGS 100, for example, via a wired or wireless communication network or based on certain electrical connections. In such a case, the PCB 116 and the processing circuitry may access the signal values from the EGS 100 and perform processing remotely.

[0088] In one of the exemplary embodiments, the sensor assembly includes a first sensor cap positioned at a first end of the sensor assembly and a second sensor cap positioned at a second end of the sensor assembly. The first sensor cap defines a first capillary and the second sensor cap defines a second capillary. The sensor assembly further includes a first sensing unit, a second sensing unit, and a filter. The first sensing unit and the second sensing unit are positioned between the first sensor cap and the second sensor cap. Further, the filter is positioned on the second capillary. The filter that is reactive to the target gas is configured to prevent the target gas from flowing into the second capillary. Further, the first capillary is configured to allow the target gas to flow into the sensor assembly.

[0089] In one of the exemplary embodiments, the first sensing unit includes a sensing electrode, a reference electrode, and a counter electrode. The sensing electrode may be positioned on the first end of the sensor assembly. The second sensing unit includes an auxiliary electrode positioned on the second end of the sensor assembly. The reference electrode and the counter electrode are positioned between the sensing electrode and the auxiliary electrode.

[0090] Further, according to some example embodiments, the sensor assembly further includes a printed circuit board (PCB) coupled to the sensor assembly. The printed circuit board is configured to determine a first current based on a first reaction between a target gas and the first sensing unit in the presence of at least one environmental parameter, and to determine a second current based on a second reaction at the second sensing unit.

[0091] Further, according to some example embodiments, the first current corresponds to the amount of the target gas at the first sensing unit, and the second current corresponds to the magnitude of the at least one environmental parameter.

[0092] In some embodiments, the EGS may include a laminated capillary that serves as a filter when coupled to the auxiliary electrode. The laminated capillary may be operable to prevent the target gas from passing therethrough.

[0093] According to some example embodiments described herein, an electrochemical gas sensor (EGS) as described herein may correspond to a carbon monoxide sensor. In some embodiments, for example, when the EGS is a carbon monoxide sensor, carbon monoxide (CO) may be reduced at the sensing electrode according to the following half-reaction:

[0094] At the sensing electrode: (Equation 1)

[0095] At the counter electrode: (Equation 2)

[0096] Battery reaction: .

[0097] In this regard, the overall reaction inside the sensor may result in the consumption of carbon monoxide. In other embodiments, other gases may be consumed and generated according to other half-reactions to achieve a substantially balanced redox reaction that is similar but different from the reaction described by way of example with reference to the carbon monoxide sensor herein. In some embodiments, the overall reaction may optionally be maintained by means of a reference electrode and a potentiostat, which may be operable to reduce the potential at the sensing electrode 216 and allow the reaction to proceed. The resulting current between the sensing electrode 216 and the counter electrode 222 may be proportional to the concentration of the ambient gas, and thus the concentration of the target gas (e.g., carbon monoxide) may be measured and / or monitored thereby by the carbon monoxide sensor.

[0098] Further, according to some example embodiments, the EGS 100 can be used for formaldehyde detection in a home environment. The carbon cloth (i.e., the filter) can be positioned on the second capillary to keep formaldehyde away from the auxiliary electrode. The four-electrode sensor gives two current signals: a first current I sens at the sensing electrode and a second current I aux at the auxiliary electrode. I sens can include a baseline current I base and a response current I resp from the electrochemical reaction of the target gas, while the second current I aux can be just the current from the baseline. The response current I resp (also known as the differential current) is caused by changes in environmental parameters, and thus by using the following relationship, the change in the target gas concentration is:

[0099] I sens = I base + I resp ,

[0100] I aux = I base

[0101] Therefore, I resp = I sens -I aux 。

[0102] According to some example embodiments described herein, the first dimension of the first capillary can be the same as the second dimension of the second capillary.

[0103] In some example embodiments, certain operations herein can be modified or further amplified as described below. Additionally, in some embodiments, additional optional operations can also be included. It should be understood that each of the modifications, optional additions, or amplifications described herein can be included alone or in combination with any other of the features described herein.

[0104] The foregoing method descriptions and process flow diagrams are provided only as illustrative examples and are not intended to require or imply that the steps of the various embodiments must be performed in the order presented. As will be understood by those skilled in the art, the steps in the foregoing embodiments can be performed in any order. Words such as "thereafter", "then", "next", etc. are not intended to limit the order of the steps; these words are only used to guide the reader through the description of the method. Further, any reference to a claim element in the singular (e.g., using the articles "a", "an", or "the") should not be construed as limiting the element to the singular.

[0105] Hardware for implementing the various illustrative logics, logic blocks, modules, and circuits described in connection with the aspects disclosed herein may include a general-purpose processor, a digital signal processor (DSP), such as an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA), programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. The general-purpose processor may be a microprocessor, but alternatively, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. Alternatively or additionally, some steps or methods may be performed by circuitry for a given function.

[0106] In one or more example embodiments, the functions described herein may be implemented by special purpose hardware or by a combination of hardware programmed with firmware or other software. In an implementation that relies on firmware or other software, the functions may be performed as a result of executing one or more instructions stored on one or more non-transitory computer-readable media and / or one or more non-transitory processor-readable media. These instructions may be embodied by one or more processor-executable software modules present on the one or more non-transitory computer-readable or processor-readable storage media. In this regard, the non-transitory computer-readable or processor-readable storage media may include any storage media accessible by a computer or a processor. Combinations of the above types of media are also included within the scope of the term non-transitory computer-readable and processor-readable media. Additionally, any combination of instructions stored on the one or more non-transitory processor-readable or computer-readable media may be referred to herein as a computer program product.

[0107] Benefiting from the foregoing description and the teachings presented in the associated drawings, those skilled in the art to which this invention pertains will envision many modifications and other embodiments of the invention set forth herein. Although the drawings only show certain components of the devices and systems described herein, it should be understood that various other components may be used in conjunction with the supply management system. Accordingly, it should be understood that the invention is not limited to the particular embodiments disclosed and that the modifications and other embodiments are intended to be included within the scope of the appended claims. Additionally, the steps in the above methods may not necessarily occur in the order depicted in the drawings, and in some cases, one or more of the depicted steps may occur substantially simultaneously, or may involve additional steps. Although specific terms are employed herein, they are used in a general and descriptive sense only and not for purposes of limitation.

Claims

1. A sensor assembly, comprising: A first sensor cover disposed on a first end of the sensor assembly, the first sensor cover defining a first capillary therethrough, the first capillary being configured to allow a target gas to pass therethrough; A second sensor cover disposed on a second end of the sensor assembly, the second sensor cover defining a second capillary therethrough; A first sensing unit, the first sensing unit including a sensing electrode disposed on the first end of the sensor assembly; A second sensing unit, the second sensing unit including an auxiliary electrode disposed on the second end of the sensor assembly, wherein each of the sensing electrode and the auxiliary electrode is positioned between the first sensor cover and the second sensor cover; and A filter mounted in a cavity defined by the second sensor cover and disposed on the second capillary and defined by a material reactive to the target gas, wherein the filter is configured to prevent the target gas from flowing in through the second capillary.

2. The sensor assembly according to claim 1, wherein, The first sensing unit further includes: A reference electrode; and A counter electrode, wherein the reference electrode and the counter electrode are positioned between the sensing electrode and the auxiliary electrode.

3. The sensor assembly according to claim 1, wherein, The filter includes at least one of a porous PTFE membrane or a glass fiber membrane, potassium permanganate, or a mixture of potassium permanganate and glass fiber.

4. The sensor assembly according to claim 3, wherein, The filter includes an activated carbon filter.

5. The sensor assembly according to claim 3, wherein, The potassium permanganate absorbs volatile organic compounds (VOCs) and formaldehyde content present in the target gas.

6. The sensor assembly according to claim 1, further comprising a printed circuit board (PCB) coupled to the sensor assembly, the printed circuit board being configured to: Determine a first current based on a first reaction between the target gas and the first sensing unit in the presence of at least one environmental parameter; and Determine a second current based on a second reaction at the second sensing unit.

7. The sensor assembly according to claim 6, wherein, The first current corresponds to the amount of the target gas at the first sensing unit, and the second current corresponds to the magnitude of the at least one environmental parameter.

8. The sensor assembly according to claim 7, wherein, The printed circuit board is further configured to determine a differential current based on the first current and the second current, wherein the differential current corresponds to the amount of a noise level based on the magnitude of the at least one environmental parameter.

9. The sensor assembly according to claim 6, wherein, The at least one environmental parameter includes at least one of a temperature value or a humidity value within the sensor assembly.

10. The sensor assembly according to claim 1, wherein, The first capillary is configured to allow the target gas to flow into the sensor assembly.

11. A sensor assembly, comprising: A housing, the housing including: A first sensor cover disposed on a first end of the housing, the first sensor cover defining a first capillary, the first capillary being configured to allow a target gas to pass therethrough; A second sensor cover disposed on a second end of the housing, the second sensor cover defining a second capillary; A first sensing unit; A second sensing unit, wherein each of the first sensing unit and the second sensing unit is respectively positioned between the first sensor cover and the second sensor cover; and A filter, the filter being installed in a cavity defined by the second sensor cover and defined by a material reactive to the target gas, and being positioned in fluid communication with the second capillary, the filter being configured to prevent the target gas from flowing therethrough.

12. The sensor assembly according to claim 11, wherein, The first sensing unit includes: A sensing electrode coupled to the first capillary; A reference electrode; and A counter electrode, and Wherein, the second sensing unit includes an auxiliary electrode coupled to the second capillary within the housing, and wherein the reference electrode and the counter electrode are positioned between the sensing electrode and the auxiliary electrode.

13. The sensor assembly according to claim 11, wherein, The filter includes at least one of a porous PTFE membrane or a glass fiber membrane, potassium permanganate, and a mixture of potassium permanganate and glass fiber.

14. The sensor assembly according to claim 11, further comprising a printed circuit board configured to: Determine a first current based on a first reaction in the presence of at least one environmental parameter; and Determine a second current based on a second reaction at the second sensing unit.

15. The sensor assembly according to claim 14, wherein, The first current corresponds to the amount of the target gas at the first sensing unit, and the second current corresponds to the magnitude of the at least one environmental parameter at the second sensing unit.

16. The sensor assembly according to claim 15, wherein, The printed circuit board is further configured to determine a differential current based on the first current and the second current, wherein the differential current corresponds to the amount of the noise level based on the magnitude of the at least one environmental parameter.

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