Patent Description:
The present specification generally relates to a breath sampling device interfaced with one or more sensors, for example, microelectronic gas sensors, printed gas sensors, or the like.

Sensors including electrochemical cells are used for detection of certain gases, for example, toxic gases and gases in a person's breath. In some sensors, high temperatures and high relative humidity may reduce the accuracy of sensor measurements.

Accordingly, breath sampling devices are desired that mitigate the effects of temperature and relative humidity of a gas sample before the gas sample enters a sensor configured to measure the gas sample.

In one embodiment, a breath sampling device including a housing having a fluid inlet positioned at a fluid inlet end, a fluid outlet positioned at a fluid outlet end, a fluid channel extending between the fluid inlet and the fluid outlet, and a sensor fluidly coupled to the fluid channel. The sensor is structurally configured to detect a presence of a target gas in a gas sample and a filter assembly fluidly coupled to the fluid channel and positioned between the fluid inlet and the sensor. The filter assembly is structurally configured to absorb heat, water vapor, or a combination thereof.

In another embodiment, a breath sampling device including a housing having a fluid inlet positioned at a fluid inlet end, a fluid outlet positioned at a fluid outlet end, a fluid channel extending between the fluid inlet and the fluid outlet, and a printed gas sensor fluidly coupled to the fluid channel. The printed gas sensor is structurally configured to detect a presence of a target gas in a gas sample. The breath sampling device includes a humidity shield fluidly coupled to the fluid channel and positioned in a fluid flow path upstream the printed gas sensor and, upon contact between a gas sample and the humidity shield, the humidity shield absorbs water vapor present in the gas sample.

In another embodiment, a breath sampling device including a housing having a fluid inlet positioned at a fluid inlet end, a fluid outlet positioned at a fluid outlet end, a fluid channel extending between the fluid inlet and the fluid outlet, and a printed gas sensor fluidly coupled to the fluid channel. The printed gas sensor is structurally configured to detect a presence of a target gas in a gas sample. The breath sampling device includes a heat dissipation shield fluidly coupled to the fluid channel and positioned in the fluid flow path upstream the printed gas sensor and, upon contact between a gas sample and the heat dissipation shield, the heat dissipation shield absorbs heat present in the gas sample.

According to the present invention, a breath sampling device includes a housing having a fluid inlet positioned at a fluid inlet end, a fluid outlet positioned at a fluid outlet end, a fluid channel extending between the fluid inlet and the fluid outlet, and a gas sensor fluidly coupled to the fluid channel. The gas sensor is structurally configured to detect a presence of a target gas in a gas sample. The breath sampling device includes a humidity shield fluidly coupled to the fluid channel and positioned in a fluid flow path upstream the gas sensor and, upon contact between a gas sample and the humidity shield, the humidity shield absorbs water vapor present in the gas sample. The breath sampling device further includes a heat dissipation shield fluidly coupled to the fluid channel and positioned in the fluid flow path upstream the gas sensor and, upon contact between a gas sample and the heat dissipation shield, the heat dissipation shield absorbs heat present in the gas sample. The gas sensor may be a printed gas sensor.

In yet another embodiment, a breath sampling device includes a housing having a fluid inlet positioned at a fluid inlet end, a fluid outlet positioned at a fluid outlet end, and a fluid channel extending between the fluid inlet and the fluid outlet. The fluid channel is bounded by an inner surface of the housing. The breath sampling device includes a heat dissipation shield covering a portion of the inner surface of the housing and, upon contact between a gas sample and the heat dissipation shield, the heat dissipation shield absorbs heat present in the gas sample. The breath sampling device further includes a plug portion removably positionable in the fluid outlet, the plug portion comprising a humidity shield and, upon contact between a gas sample and the humidity shield, the humidity shield absorbs water vapor present in the gas sample.

Document <CIT> relates to a breath gas analysis detector which comprises a humidity reducing device.

Embodiments of the present disclosure are directed to a breath sampling device comprising a sensor configured to measuring the presence, amount, and/or concentration of a target gas in a gas sample and comprising a filter assembly configured to modify various properties of the gas sample before the gas sample enters the sensor. The filter assembly includes a heat dissipation shield configured to absorb heat present within the gas sample before the gas sample enters the sensor and the filter assembly also includes a humidity shield configured to absorb water vapor present within the gas sample before the gas sample enters the sensor. In operation, the heat dissipation shield slows the entrance of heat into the sensor and the humidity shield slows the entrance of water vapor into the sensor. Further, in operation, the filter assembly increases the accuracy and effectiveness of sensor measurements performed by the sensor by allowing the gas sample to enter the sensor with temporarily normalized (e.g., reduced) temperature and relative humidity.

Referring now to <FIG>, the breath sampling device <NUM> is depicted. The breath sampling device <NUM> comprises a housing <NUM> having a fluid inlet <NUM> positioned at a fluid inlet end <NUM> of the housing <NUM> and a fluid outlet <NUM> positioned at a fluid outlet end <NUM> of the housing <NUM>. The fluid inlet <NUM> and the fluid outlet <NUM> are fluidly coupled by a fluid channel <NUM> that extends between the fluid inlet <NUM> and the fluid outlet <NUM>. Further, a fluid flow path <NUM> extends along the fluid channel <NUM>. In some embodiments, the fluid channel <NUM> may comprise a Nafion™ tube and the fluid inlet <NUM> and the fluid outlet <NUM> may be fluidly coupled by a Nafion™ tube. In this embodiments, the fluid channel <NUM> may comprise a humidity shield <NUM>, as described in more detail below. In some embodiments, the housing <NUM> comprises one or more chemically inert plastic materials, such as polytetrafluoroethylene (PTFE), polyimide, polycarbonate substrate, polyethylene terephthalate (PET) substrate, fluorinated ethylene propylene (FEP), polyether ether ketone (PEEK), acrylic, polypropylene (PP), or the like. The housing <NUM> may be any size, for example, between about <NUM><NUM> and about <NUM><NUM>, such as <NUM><NUM>, <NUM><NUM> , <NUM><NUM>, or the like. Further, the housing <NUM> may be porous or partially porous (e.g., porous to some but not all gases). The size and porosity of the housing <NUM> may be configured to not impede the target gas of the gas sample.

In some embodiments, as depicted in <FIG>, the housing <NUM> may have a smaller cross sectional area at the fluid inlet end <NUM> than at the fluid outlet end <NUM>. For example, the fluid inlet <NUM> may have a smaller cross sectional area (e.g., a smaller diameter) than the fluid outlet <NUM>. Further, the fluid channel <NUM> may comprise a tapered shape, increasing in cross sectional area from the fluid inlet end <NUM> to the fluid outlet end <NUM>. In some embodiments, as depicted in <FIG>, the fluid inlet <NUM> and the fluid outlet <NUM> may comprise uniform cross sectional areas. In other embodiments, the housing <NUM> may have a larger cross sectional area at the fluid inlet end <NUM> than at the fluid outlet end <NUM>. It should be understood that any housing <NUM> shape is contemplated.

In some embodiments, the fluid inlet <NUM> is fully or partially restricted. For example, a portion of a filter assembly <NUM> (e.g., a humidity shield <NUM>) may be positioned in the fluid inlet <NUM> to form an interface at the fluid inlet <NUM>. By restricting flow at the fluid inlet <NUM>, the flowrate of the gas sample entering the fluid channel may be altered, for example, slowed. Further, in some embodiments, the fluid outlet <NUM> may be partially or fully restricted such that gas sample introduced into the fluid channel <NUM> is directed into a sensor <NUM>. In some embodiments, the housing <NUM> may have an adjustable design to accommodate variable gas samples and variable gas sample input times. For example, the housing <NUM> may comprise a larger volume and a larger throughput to facilitate larger gas samples. In some embodiments, the housing <NUM> may be sized and configured for a specific gas sample size and a specific gas sample input time.

Referring still to <FIG>, the sensor <NUM> of the breath sampling device <NUM> is fluidly coupled to the fluid channel <NUM> such that when the gas sample is introduced into the fluid channel <NUM>, at least a portion of the gas sample enters the sensor <NUM>. As described in more detail below, the sensor <NUM> may comprise a printed gas sensor. The sensor <NUM> is configured to measure a presence of the target gas in the gas sample and in some embodiments the sensor <NUM> is configured to measure an amount and/or concentration of target gas in the gas sample. As an example and not a limitation, the target gas may comprise H<NUM>S, Ketone, NO, CO, ethanol, CH<NUM>, or the like. In some embodiments, the gas sample may be a user's breath and the sensor <NUM> may be configured to measure H<NUM>S, Ketone, NO, CO, and/or ethanol in the user's breath. In other embodiments, the gas sample may comprise an environmental gas sample, such as, natural gas, mercaptan, or the like. In one example embodiment, the sensor <NUM> may be configured to measure a target gas comprising H<NUM>S in a gas sample comprising mercaptan and in another embodiment, the sensor <NUM> may be configured to measure a target gas comprising CH<NUM> in a gas sample comprising natural gas or other hydrocarbons in gas or oil products. In operation, the gas sample may be introduced into the breath sampling device <NUM> with range of flowrates and pressures.

Referring still to <FIG>, the filter assembly <NUM> is fluidly coupled to the sensor <NUM> such that a portion of the gas sample that enters the fluid channel <NUM> contacts and/or traverses the filter assembly <NUM> before entering the sensor <NUM>. The filter assembly <NUM> may comprise a heat dissipation shield <NUM>, a humidity shield <NUM>, or a combination of both. The heat dissipation shield <NUM> and the humidity shield <NUM> may be positioned within the fluid flow path <NUM> between the fluid inlet <NUM> and the sensors <NUM>, for example, within the fluid channel <NUM>, coupled to the sensors <NUM>, integrated into the sensors <NUM>, positioned within the fluid inlet <NUM>, and/or positioned within the fluid outlet <NUM>. The heat dissipation shield <NUM> may be positioned upstream the humidity shield <NUM>, such that the gas sample traverses the heat dissipation shield <NUM> before traversing the humidity shield <NUM>, or downstream the humidity shield <NUM>, such that the gas sample traverses the humidity shield <NUM> before traversing the heat dissipation shield <NUM>. Further, both the heat dissipation shield <NUM> and the humidity shield <NUM> are positioned upstream the sensors <NUM>.

In some embodiments, the humidity shield <NUM> comprises any device or material configured to temporarily reduce (e.g., buffer) the relative humidity of the gas sample by temporarily absorbing and retaining water vapor present in the gas sample. The humidity shield <NUM> may comprise Nafion™, for example a Nafion™ coating or substrate, a Nafion™ treated porous media such as filter paper, porous polypyrrole (PPY), or the like. In some embodiments, the humidity shield <NUM> may comprise one or more of glycerol, glycerol sulfuric acid, polyvinyl alcohol (PVA), humectant, a room temperature ionic liquid (RTIL), a porous wick material, or the like. Further, the humidity shield <NUM> may comprise a sampler, an interface, a coating, a gas chromatograph, or the like.

In operation, the humidity shield <NUM> may separate the target gas from water vapor present in the gas sample by receiving the gas sample and temporarily or permanently absorbing and retaining a portion of the water vapor present in the gas sample, for example, through relative capacitive migration. For example, the humidity shield <NUM> may be configured to retain an excess portion of the water vapor above a normalization level. The normalization level may comprise the relative humidity (e.g., water vapor) present in the humidity shield <NUM>. If the relative humidity of the gas sample is higher than the normalization level, the humidity shield <NUM> will temporarily or permanently absorb the excess portion water vapor. For example, if the humidity shield <NUM> is designed with a normalization level of about <NUM>% relative humidity, the humidity shield <NUM> will temporarily or permanently retain any excess water vapor above <NUM>% relative humidity. Further, the humidity shield <NUM> may absorb and retain water vapor for a buffering period, for example, between about <NUM> and about <NUM> seconds, for example, <NUM> seconds, <NUM> second, <NUM> second, or the like. Further, in some embodiments, the humidity shield <NUM> may be configured to buffer the flowrate of the gas sample.

In some embodiments, as depicted in <FIG>, the humidity shield <NUM> may be positioned at the fluid inlet <NUM>, for example, the humidity shield <NUM> may be positioned in an inlet filter interface <NUM>, for example, a coating or substrate comprising any of the components of the humidity shield <NUM> described above. The inlet filter interface <NUM> is porous and may fully or partially cover the fluid inlet <NUM>. In some embodiments, the inlet filter interface <NUM> comprises a replaceable filter mouthpiece <NUM> that is removably engageable with to the fluid inlet <NUM>. The humidity shield <NUM> (e.g., a Nafion™ coating, or the like) may be positioned within the replaceable filter mouthpiece <NUM> and in operation, the humidity shield <NUM> may be regenerated (e.g., automatic regeneration after a period of time) or replaced.

Referring again to <FIG>, the heat dissipation shield <NUM> comprises any device or material configured to temporarily reduce (e.g., buffer) the temperature of the gas sample by temporarily or permanently absorbing and retaining heat present in the gas sample, for example, through heat distribution and upon contact between the gas sample and the heat dissipation shield <NUM>. The heat dissipation shield <NUM> may comprise thermally conductive metals and ceramics configured to remove heat from the gas sample without substantially reacting with or impeding the target gas. For example, the heat dissipation shield <NUM> may comprise a metal foil, such as aluminum foil, copper foil, a metalized Mylar, a thin metal coating, a porous metal screen, a TFE coated metal screen, any high thermal transfer media, or the like. Further, the heat dissipation shield <NUM> may comprise one or more of a sampler, an interface, a coating, a gas chromatograph, or the like. In some embodiments, the heat dissipation shield <NUM> may be configured to buffer the flowrate of the gas sample.

Referring now to <FIG>, the heat dissipation shield <NUM> may comprise a metal foil having an array of holes <NUM> disposed through a surface <NUM> of the heat dissipation shield <NUM>. In some embodiments, the arrays of holes <NUM> are disposed through a portion of the surface <NUM> (<FIG>) and in other embodiments, the array of holes <NUM> are disposed though the entire surface <NUM> (<FIG>). In operation, the gas sample may travel over the surface <NUM>, which removes heat from the gas sample and then pass through the array of holes <NUM>. The longer the gas sample contacts the surface <NUM>, the more heat may be removed from the gas sample. Further, smaller and/or fewer holes within the array of holes <NUM> may facilitate increased heat removal. The array of holes <NUM> may comprise uniform or non-uniform shapes and cross sectional areas (e.g., diameters in embodiments comprising round holes). For example, the array of holes <NUM> may comprise diameters of between about <NUM> and <NUM>, e.g., about <NUM>, <NUM>, <NUM>, or the like.

Referring again to <FIG>, the heat dissipation shield <NUM> may be a baffle comprising tubes, tube bundles, flow-directing vanes, obstructing vanes, panels, or a combination thereof. In some embodiments, the baffle may comprise a slot or a tube positioned within the fluid channel <NUM> and may comprise a length to diameter ratio of between about <NUM>/<NUM> and about <NUM>/<NUM>, for example, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/<NUM>, or the like. In some embodiments, as depicted in <FIG>, the heat dissipation shield <NUM> may be aerodynamic (e.g., an aerodynamic baffle) such that the heat dissipation shield minimally intrudes the fluid flow path <NUM> of the fluid channel <NUM>. In some embodiments, the aerodynamic heat dissipation shield <NUM> may be positioned in the fluid channel <NUM> when minimal gas sample flowrate alteration is desired. Further, the heat dissipation shield <NUM> may be porous or non-porous. When the heat dissipation shield <NUM> is non-porous, the gas sample may contact the heat dissipation shield <NUM> without passing through the heat dissipation shield <NUM>. An example non-porous heat dissipation shield <NUM> is depicted in <FIG>, described in more detail below, in which the heat dissipation shield <NUM> comprises foil disposed on inner surface of the housing <NUM>, such that the foil is positioned in the fluid channel <NUM>.

In operation, the heat dissipation shield <NUM> may buffer and/or reduce the temperature in the gas sample, which may reduce the effects of temperature on the measurements performed by the sensor <NUM>. For example, a gas sample comprising a temperature of about <NUM>° C can traverse the heat dissipation shield <NUM> and enter the one or more sensors <NUM> at a temperature between about <NUM>° C and about <NUM>° C, such as about <NUM>° C, <NUM>° C, <NUM>° C, or the like. In some embodiments, the heat dissipation shield <NUM> may absorb and retain heat for a buffering period, for example, between about <NUM> and about <NUM> seconds, for example, <NUM> seconds, <NUM> second, <NUM> second, or the like.

Referring to <FIG>, <FIG>, the heat dissipation shield <NUM> may be coupled to or adjacent the humidity shield <NUM>. For example, the heat dissipation shield <NUM> having the array of holes <NUM> may be positioned adjacent the humidity shield <NUM> such that the gas sample passes over the surface <NUM> of the heat dissipation shield <NUM> and through the array of holes <NUM> before or after entering the humidity shield <NUM>. After traversing the heat dissipation shield <NUM> and the humidity shield <NUM>, the gas sample enters the sensor <NUM>. In one example embodiment, the heat dissipation shield <NUM> comprises about <NUM>-<NUM> layers of aluminum foil (e.g., about <NUM>-<NUM> mils) and the humidity shield <NUM> comprises between about <NUM> and <NUM> of a porous material coated with Nafion™, for example, about <NUM>, <NUM>, and <NUM>, or the like. In some embodiments, the heat dissipation shield <NUM> and the humidity shield <NUM> are combined in a single material, for example, a composite material comprising a foil material coated or combined with Nafion™, or the like.

In operation, temperature or relative humidity present in the gas sample above or below a desired range may cause measurement errors in the sensor <NUM>. Further, temperature or relative humidity may have an increased effect when the gas sample includes a small amount of the target gas, for example, when the target gas is present in part per million (ppm) or part per billion (ppb) levels, such as between about <NUM> ppb and about <NUM> ppb of the target gas. Further, in one example embodiment, a <NUM>° C gas sample having a relative humidity of <NUM>% may enter the breath sampling device <NUM> and traverse the filter assembly <NUM> which lowers the temperature to about <NUM>° C and lowers the relative humidity to about <NUM>%.

Referring now to <FIG>, another breath sampling device <NUM> is depicted. The breath sampling device <NUM> includes a housing <NUM> having a fluid inlet <NUM>, a fluid outlet <NUM>, and a fluid channel <NUM> extending therebetween. In some embodiments, a nozzle <NUM> may be positioned in the fluid inlet <NUM>. The nozzle <NUM> may comprise any fluid nozzle configured to receive a gas sample. Further, a tube <NUM> may be coupled to the nozzle <NUM> such that a user may provide a gas sample through the tube <NUM>. The housing <NUM> comprises an inner surface <NUM> facing the fluid channel <NUM> and a heat dissipation shield <NUM> that may be positioned in the housing <NUM>, for example, partially or fully covering the inner surface <NUM>. For example, the heat dissipation shield <NUM> may comprise a metal foil that covers the inner surface <NUM> of the housing <NUM>.

Referring now to <FIG> and <FIG>, the breath sampling device <NUM> may further comprise a plug portion <NUM> removably engageable with the housing <NUM>, for example with a plug receiving portion <NUM> of the housing <NUM>. In some embodiments, the plug receiving portion <NUM> is the fluid outlet <NUM> of the housing <NUM>. In other embodiments, the plug receiving portion <NUM> and the fluid outlet <NUM> are positioned in different locations of the housing <NUM>. In some embodiments, the plug portion <NUM> includes a humidity shield <NUM>. The plug portion <NUM> and the humidity shield <NUM> can vary in size to control the amount of gas sample that enters the sensor <NUM>, depicted in <FIG>, below.

In operation, when the gas sample enters the housing <NUM>, the heat dissipation shield <NUM> covering the inner surface <NUM> of the housing <NUM> absorbs heat in the gas sample upon contact between the gas sample and the heat dissipation shield <NUM>. Next, the gas sample exits the housing <NUM> through the plug portion <NUM> comprising the humidity shield <NUM> which, upon contact between the gas sample and the humidity shield <NUM>, absorbs water vapor from the gas sample before the gas sample enters the sensor <NUM>. Referring now to <FIG> and <FIG>, the sensor <NUM> may be positioned on a printed circuit board <NUM>. Further, the sensor <NUM> is engageable with the housing <NUM>, for example, the housing <NUM> is engageable with a gas inlet region <NUM> positioned in a substrate <NUM> of the sensor <NUM> such that the gas sample passes through the plug portion <NUM> before entering the sensor <NUM>.

In operation, after the heat dissipation shield <NUM> and the humidity shield <NUM> may require some recovery time, (e.g., the time it takes for temperature and relative humidity to return to baseline levels after the gas sample has entered the breath sampling device <NUM>). The recovery time may be correlated with the design of the breath sampling device <NUM>, for example, an example breath sampling device <NUM> having a small housing <NUM> may require a shorter recovery time than an example breath sampling device <NUM> with a larger housing <NUM>. Further, in some embodiments, the breath sampling device <NUM> may operate continuously without requiring recovery time. For example, the breath sampling device <NUM> may incorporate a compensation method, such as methods compensating for signal drift, known temperatures, and known relative humidities. In operation, the small components allow the breath sampling device <NUM> to reach steady state quickly, e.g., steady state within <NUM>-<NUM> seconds. Another example compensation method includes altering the signal speed by changing the thickness of the materials.

Referring again to <FIG>, the sensor <NUM> may comprise a printed gas sensor, a microelectromechanical gas sensor, or the like, for example the printed gas sensors disclosed in <CIT> titled "Printed Gas Sensor". As an example and not a limitation, some embodiments of the sensor <NUM> are described below, although any exemplary sensor is contemplated. In some embodiments, the sensor <NUM> comprises a substrate layer <NUM> (e.g., a porous substrate or a partially porous substrate), one or more electrodes <NUM>, an electrolyte cavity <NUM> or layer that houses liquid or gel electrolyte in electrolytic contact with the one or more electrodes <NUM>, and an encapsulation layer <NUM>. In some embodiments, the substrate layer <NUM> includes one or more gas access regions <NUM> fluidly coupled to the fluid channel <NUM> of the breath sampling device <NUM> to allow the gas sample to enter the sensor <NUM> and can be any shape and size. While one sensor <NUM> is depicted in <FIG>, <FIG>, and <FIG>, it should be understood that any number of sensors <NUM> are contemplated.

The substrate layer <NUM> may comprise one or more partially porous substrates coupled together using pressure sensitive adhesive, or the like. The substrate layer <NUM> may comprise low temperature plastics such as polycarbonate substrate and PET, and/or high temperature material such as PTFE, porous PTFE, or polyimide. The encapsulation layer <NUM> may comprise a tetrafluoroethylene (TFE) substrate, or other plastic and can be utilized to block gas access. In some embodiments, the filter assembly <NUM> is positioned on the substrate layer <NUM> such that the gas sample must pass through the filter assembly <NUM> before traversing the one or more gas access regions <NUM> of the substrate layer <NUM>.

The one or more electrodes <NUM> may be coupled to a wick <NUM> comprising porous glass fiber or glass fiber filter paper or may be coupled directly to the substrate layer <NUM>. The one or more electrodes <NUM> may be screen printed, inkjet printed, stamped, or stenciled onto the wick <NUM> or substrate layer <NUM>. The substrate layer <NUM> may further comprise a printed runner <NUM> facing the electrolyte cavity <NUM>. The electrolyte cavity <NUM> may house an electrolyte, for example H<NUM>SO<NUM>. The one or more electrodes <NUM> may comprise PTFE liquid, PTFE powder, polypropylene powder or polyethylene powder, as well as catalyst, solvents, and additives, such as, for example, platinum, palladium, or alloys or supported catalysts like platinum on carbon. In some embodiments, multiple electrodes <NUM> may be configured to each detect different target gases. For example, a first electrode can detect CO and a second electrode can detect gases such as H<NUM>S, O<NUM>, SO<NUM>, or NO<NUM>. In some embodiments, the one or more electrodes <NUM> are curable at temperatures lower than the melting point and deformation point of the materials of the sensor <NUM>.

In operation, the electrochemical reaction between the electrode <NUM>, the electrolyte, and the target gas generates an electric current in the printed runner <NUM> and sends electric signal to one or more circuits connected to the printed runner <NUM> at one or more electrical contact points <NUM>. This electric signal communicates to one or more circuits that a target gas is detected in the sensor <NUM>. It should be understood that any sensor <NUM> configured to evaluate a gas sample may be included in the breath sampling device <NUM>, <NUM> of the present disclosure, for example, any sensor <NUM> having temperature and relative humidity sensitivities. In some embodiments, sensors <NUM> having a pt/Ru catalyst may provide a fast response time and a high bias for large signals. Additionally, optimization of the target gas may be performed in the sensor <NUM>. Some sensors <NUM> having electrolytes comprising RTIL may have lower relative humidity signals and lower temperature coefficients.

In one example, a dual sensor compensation method is contemplated allowing one or more sensors <NUM> to measure multiple target gases in the gas sample without a first target gas altering the measurement of a second target gas, and vice versa. In one example embodiment, two sensors <NUM> are contemplated, one configured to measure nitric oxide (NO) and another configured to measure H<NUM>S. To compensate for NO interference, the breath sampling device <NUM> may include two sensors, a first sensor for NO detection having a H<NUM>S filter (e.g., bicarbonate) and a second sensor having a filter that responds to NO and H<NUM>S. The difference in the sensor measurements allows for computation of both NO and H<NUM>S concentrations. For example, when the gas sample is a user's breath, NO on the breath may be an indicator of asthma and/or stress. In other embodiments, this dual sensor compensation method may be used to compensate for acetone, CO<NUM> or other example gas samples.

In some embodiments, the effects of temperature and relative humidity on the one or more sensors <NUM> may be minimized by an additional electrode, such as, for example, a compensation electrode. The compensation electrode may be configured as a working electrode communicatively coupled to a differential amplifier which generates a signal that can be subtracted from the primary signal measurements. The compensation electrode may compensate for the effects of temperature and relative humidity on the sensor measurement. In some embodiments, the compensation electrode may be buried under a gas impermeable layer of low thermal mass material, (i.e. Nafion™, or the like, as described above configured to absorb water vapor). Additionally, in some embodiments, a catalyst with a low surface area may be coupled to the one or more electrodes <NUM> to increase the signal to noise ratio of the one or more sensors <NUM> and reduce the magnitude of the baseline effects of temperature and relative humidities. This may allow use of higher gain to improve resolution of the sensor <NUM>. In some embodiments, the method detection limit of the sensor <NUM> for the measurement of the target gas is between about <NUM> ppb and about <NUM> ppb of the target gas, e.g., about <NUM> ppb, <NUM> ppb, <NUM> ppb, or the like.

It should now be understood that breath sampling devices are contemplated that include a sensor configured to measuring the presence, amount, and/or concentration of a target gas in a gas sample and a filter assembly configured to modify various properties of the gas sample before the gas sample enters the sensor. The filter assembly includes a humidity shield and/or the heat dissipation shield. The heat dissipation shield is configured to absorb heat present within the gas sample before the gas sample enters the sensor and the humidity shield is configured to absorb water vapor present within the gas sample before the gas sample enters the sensor. In operation, the heat dissipation shield slows the entrance of heat into the sensor and the humidity shield slows the entrance of water vapor into the sensor. Reducing the temperature and the relative humidity of the gas sample that enters the sensor may increase the accuracy and effectiveness of sensor measurements.

It is noted that the term "substantially" may be utilized herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. This term is also utilized herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue.

Claim 1:
A breath sampling device (<NUM>) comprising:
a housing (<NUM>) having a fluid inlet (<NUM>) positioned at a fluid inlet end (<NUM>), a fluid outlet (<NUM>) positioned at a fluid outlet end (<NUM>), and a fluid channel (<NUM>) extending between the fluid inlet (<NUM>) and the fluid outlet (<NUM>);
a gas sensor (<NUM>) fluidly coupled to the fluid channel (<NUM>), wherein the gas sensor (<NUM>) is structurally configured to detect a presence of a target gas in a gas sample;
a humidity shield (<NUM>) fluidly coupled to the fluid channel (<NUM>) and positioned in a fluid flow path (<NUM>) upstream the gas sensor (<NUM>), wherein, upon contact between a gas sample and the humidity shield (<NUM>), the humidity shield (<NUM>) reduces the humidity of the gas sample; and
a heat dissipation shield (<NUM>) fluidly coupled to the fluid channel (<NUM>) and positioned in a fluid flow path (<NUM>) upstream the gas sensor (<NUM>), wherein, upon contact between a gas sample and the heat dissipation shield (<NUM>), the heat dissipation shield (<NUM>) reduces the heat of the gas sample.