Method and apparatus for producing highly accurate mixed gas mixtures containing volatile analytes - Patents.com

Abstract

A system for producing a high precision mixed gas product (BGP) includes: a volatile analyte in liquid form; an inert carrier gas; at least one diluent gas; an analyte gasifier (AG) subsystem for receiving the volatile analyte in liquid form, nebulizing the volatile analyte, and mixing the nebulized volatile analyte with the inert carrier gas to form an analyte gas stream (AGS); a gas analyzer (GA) for receiving the AGS and analyzing the AGS; a gas proportioner for receiving the AGS from the GA and receiving at least one diluent gas and proportioning the AGS and the at least one diluent gas based on a result of the GA to provide a proportioned AGS and a proportioned at least one diluent gas; and a gas mixing chamber for receiving the proportioned AGS and the proportioned at least one diluent from the gas proportioner to produce the BGP.

Description

[Technical field]

[0001] (Reference to pending prior patent application) This patent application claims the benefit of pending U.S. Provisional Patent Application No. 62 / 894,038 (Attorney Docket No. ACTS-2 PROV), filed on August 30, 2019 by Automotive Coalition For Traffic Safety, Inc. and Brian E. Fratto et al. for “METHOD AND APPARATUS FOR PRODUCING HUMIDIFIED, CONTROLLED VOLATILE EFFLUENTS USING REAL-TIME FEEDBACK CONTROLS,” which is hereby incorporated by reference into this specification.

[0002] The present invention relates generally to methods and apparatus for generating mixed gas mixtures, and more particularly to methods and apparatus for generating highly accurate mixed gas mixtures containing volatile analytes. [Background technology]

[0003] Today, a variety of detectors are used to measure the concentration of specific gas components in a person's exhaled breath. By way of example, but not limitation, certain detectors are designed to measure the concentration of ammonia in a person's breath because evidence suggests that the presence of ammonia in a person's breath is associated with certain diseases, such as hypertension, diabetes, and cancer. Thus, detectors that can measure low concentrations of ammonia can provide an early indication of disease so that a person can receive early treatment for the disease.

[0004] As a further example, but not by way of limitation, another type of detector is designed to measure the concentration of carbon dioxide and oxygen in a person's exhaled breath. This type of detector may be used in hospitals to monitor a person's respiratory function when they are ill or injured.

[0005] Yet another type of detector, commonly referred to as a breath analyzer, is designed to measure the concentration of alcohol in a person's breath (i.e., to measure a person's breath alcohol content, sometimes referred to as "BrAC"). It will be appreciated that an alcohol detection system integrated into a vehicle can prevent a person from operating a vehicle if their BrAC is higher than the legal limit. One example of this type of alcohol detection system is the Driver Alcohol Detection System for Safety program (www.dadss.org), sometimes referred to herein as the "DADSS program."

[0006] It will therefore be appreciated that there are many situations in which it may be desirable to use a detector to measure the concentration of a particular gas component in a person's exhaled breath. For some applications, the accuracy and precision of the detector can be important. By way of example, and not by way of limitation, for a DADSS program, the detector must be able to detect human BrAC with high accuracy and precision, e.g., to within 0.0003% of the BrAC level.

[0007] In order to calibrate and test the performance of such detectors, it is necessary to be able to generate a gas mixture of known components in which the concentration of each component has been established with sufficient accuracy and precision In addition, if the gas mixture is intended to mimic human exhaled breath, the gas mixture must be appropriately humidified.

[0008] Thus, there is a need for an apparatus capable of producing highly accurate mixed gas mixtures containing volatile analytes, sometimes referred to herein as "mixed gas products" or "BGPs," that can maintain accurate and precise concentrations of the BGP's constituent components over extended periods of time, while also providing the ability to vary the concentrations of the BGP's constituent components on demand.

[0009] It is also necessary that the device be capable of producing humidified BGP. It is also necessary that the device be capable of generating BGP that mimics human breath containing volatile analytes (e.g., for testing high performance breath sensors such as the detectors in the DADSS program to identify human BrAC).

[0010] Indeed, previous attempts to provide such systems have fallen short due to the limited precision and accuracy of the prior art systems. More specifically, the commercial gas industry typically provides gases with a compositional accuracy of ±2% of the reported concentration, which limits the accuracy of gas mixtures produced by component gases obtained through commercial sources.

[0011] In addition, volatile analyte gases (e.g., ethanol, sometimes referred to herein as "EtOH") provided by commercial sources are typically supplied in tanks containing the volatile analyte gas mixed with an inert gas (e.g., helium), such that the physical properties of the gas dictate frequent tank turnover (i.e., tank replacement), thus creating the potential for additional variability and high costs. More specifically, the volatile analyte gas must be significantly diluted in the inert gas in order to remain in the gas phase. This limitation in analyte gas concentration increases the rate at which the tank empties, resulting in frequent tank replacements and thus high costs. In addition, the need for such frequent tank replacements adversely affects long-term testing, in which a precise stream of volatile analyte gas must be generated over an extended period of time, since such tank replacements introduce the potential for additional variability during testing.

[0012] In addition to the above, if the gas mixture being generated must mimic human exhaled breath, the gas mixture must be humidified before being used in the test. Due to miscibility and solubility issues, in some circumstances it is very difficult to create a homogenized gas mixture that contains both the component being volatilized (e.g., ethanol) as well as a humidity level that is reaching its temperature-dependent solubility limit. Current technologies such as wet bath (bubbler) systems are limited by the physical principles of miscibility in volatilized organic compounds. An example of this can be seen with toluene. When toluene is volatilized in a conventional aqueous bubbler, it exists as a bilayer on the surface of a denser aqueous layer, thus inhibiting the ability to create a homogenous gas mixture. Furthermore, the manner in which humidification is performed can be important. If humidification is performed too early in the process, the gas mixture can be compromised and inaccurate concentrations of analytes can be created. In other situations, if humidification occurs too late in the process, the system may be susceptible to temperature changes that may result in the nucleation of either organic or aqueous droplets that may then capture homogeneous gas components from the solution, creating a coarse colloidal aerosol rather than a uniform, finely atomized analyte.

[0013] The foregoing applies to the general problem of producing a humidified, highly accurate mixed gas mixture containing a volatile analyte. Further understanding can be gained by considering the problem of generating humidified, high precision mixed gas mixtures containing ethanol, such as those required for the calibration and testing of breath-based alcohol detectors.

[0014] More specifically, when testing breath-based alcohol detectors, early generators were created to generate humidified mixed gas mixtures using commercially available ethanol gas tanks (these early generators are sometimes referred to as "Wet Gas Breath Alcohol Simulators" or "WGBAS"). WGBAS have demonstrated the ability to generate wet breath ethanol mixtures that can meet and exceed the degree of accuracy required by DADSS programs (e.g., BrAC levels that do not vary by more than 0.0075% of the target BrAC level). However, the method of generating ethanol gas mixtures in the WGBAS device results in ethanol gas mixtures that cannot be precisely and accurately maintained over long, useful periods. Because the concentrations of the component gases in the gas mixture contained in the tank cannot be increased after the tank is filled, the WGBAS device uses a high concentration ethanol tank. The ethanol from this tank is then mixed with a carrier gas (e.g., helium, nitrogen, or other non-reactive gas) and a mass flow controller (MFC) is used to generate the final concentration ethanol gas mixture. Due to the physical properties of ethanol, the 3000 ppm ethanol gas mixture must be maintained at low pressure to ensure that the ethanol remains in a gaseous state.

[0015] This low pressure means that the tank containing the ethanol gas mixture necessarily contains a relatively small amount of ethanol, thus creating a situation where the tank must be changed frequently during testing to provide the desired amount of ethanol in the ethanol gas mixture.

[0016] Additionally, changing tanks during testing creates consistency problems during testing, with reported concentrations varying by ±2%, for example, which is typical in the commercial gas industry. This introduction of error requires constant monitoring and control to ensure that calibration or test cycles are not invalidated by the use of multiple ethanol tanks, which may give different mixtures (and thus different ethanol concentrations in the final gas product of the WGBAS device).

[0017] In addition to the above, current technologies for producing humidified, controlled ethanol gas mixtures (such as those listed in the "DEPARTMENT OF TRANSPORTATION National Highway Traffic Safety Administration [Docket No. NHTSA-2007-28067] Highway Safety Programs; Model Specifications for Calibrating Units for Breath Alcohol Testers; Conforming Products List of Calibrating Units for Breath Alcohol Testers") have limitations including (i) the maximum achievable accuracy and precision of the humidified ethanol gas mixture, and (ii) the length of time that a constant ethanol concentration can be maintained. More specifically, the technologies listed in the NHTSA model specifications are either so-called "dry gas systems" or "wet bath ("bubbler") systems." Dry gas systems consist of a tank of ethanol gas with a carrier gas (e.g., nitrogen). As mentioned above, typical gas systems provide an analytical accuracy of ±2% of the reported concentration. Because the component gases provided by commercial sources are tank-fed, the physical properties of the gases dictate frequent tank turnover (i.e., tank replacement), resulting in (i) reduced accuracy when more than one tank is used for calibration or testing, and (ii) high costs. Wet bath ("bubbler") systems consist of a heated bath containing a standardized aqueous alcohol solution through which an inert carrier gas is passed. This "bubbling" action creates a gas-phase mixture of humidified ethanol and carrier gas. Although wet bath systems provide a humidified and controlled gaseous ethanol analyte, the accuracy and precision of these systems are limited. The NHTSA model standard only requires that these systems have a standard error ("accuracy") of less than 0.002% of the BrAC level and a relative standard deviation (RSD) ("precision") of 2%. These accuracy and precision requirements are an order of magnitude lower in accuracy and precision than the DADSS program requirements.In addition, wet bath systems are known to be unable to maintain a constant ethanol concentration because the concentration of ethanol in the gas phase decreases as the ethanol in the liquid standard solution is consumed. Also, both dry gas and wet bath systems cannot be easily or accurately adjusted on demand. The ethanol concentration in a dry gas system cannot be changed after the tank is produced, and the ethanol concentration in a wet bath system can only be roughly adjusted on demand, but not accurately, precisely, and / or quickly. Summary of the Invention [Problem to be solved by the invention]

[0018] As a result, there is a need for new and improved methods and apparatus for producing highly accurate mixed gas mixtures containing volatile analytes, sometimes referred to herein as "mixed gas products" or "BGPs," that can maintain accurate and precise concentrations of the constituents of the BGP over extended periods of time, while also providing the ability to vary the concentrations of the constituents of the BGP on demand.

[0019] There is also a need for new and improved methods and apparatus for producing humidified BGP. There is also a need for new and improved methods and apparatus for producing BGPs that mimic human breath containing volatile analytes (e.g., for testing high performance breath sensors such as the detectors in the DADSS program to identify human BrAC). [Means for solving the problem]

[0020] The present invention involves the provision and use of new and improved methods and apparatus for producing highly accurate mixed gas mixtures containing volatile analytes, sometimes referred to herein as "mixed gas products" or "BGPs," which can maintain accurate and precise concentrations of the constituents of the BGP over extended periods of time, while also providing the ability to vary the concentrations of the constituents of the BGP on demand.

[0021] The present invention also includes a new and improved method and apparatus for producing humidified BGP. The present invention also includes new and improved methods and apparatus for producing BGPs that mimic human breath containing volatile analytes (e.g., for testing high performance breath sensors such as detectors for identifying human BrAC).

[0022] In one preferred form of the invention, an apparatus for generating a high precision mixed gas mixture containing a volatile analyte (i.e., a "mixed gas product" or "BGP") uses a combination of two subsystems to create the BGP: (i) an analyte gasifier (AG) subsystem that takes in a liquid form of the volatile analyte, nebulizes the volatile analyte, and mixes the nebulized volatile analyte with an inert carrier gas to generate an analyte gas stream, sometimes referred to herein as "AGS," and (ii) a gas mixer (GM) subsystem that mixes the AGS with other gases and also humidifies the AGS to generate the desired concentration of BGP with high accuracy and precision.

[0023] The Analyte Gasifier (AG) subsystem uses the thermodynamic principles of vaporization to rapidly convert a desired volatile analyte (e.g., ethanol) to its gaseous state. This formation of the desired analyte vapor (e.g., ethanol vapor) occurs in the presence of a constant flow of carrier gas (e.g., helium or another gas that does not react with the desired analyte) that is used to ensure that the concentration of the analyte vapor remains low enough that the analyte remains in a gaseous state. The AGS is then delivered to the Gas Mixer (GM) subsystem.

[0024] The Gas Mixer (GM) subsystem receives the AGS from the Analyte Gasifier (AG) subsystem and passes the AGS to the Gas Analyzer (GA), which monitors the concentration of the AGS coming from the Analyte Gasifier (AG) subsystem. The Gas Mixer (GM) subsystem also includes a gas proportioner. Data from the GA is reported to the gas proportioner, which uses this data to adjust (i) the flow rate of the AGS based on any changes in the analyte concentration of the AGS, and (ii) the flow rate of one or more diluent gases (e.g., O, HO, NH ... 2 , CO 2 and N 2 ) is appropriately proportioned. The proportioned CDGS exiting the gas proportioner enters a temperature controlled chamber and is then humidified to produce a gas stream sometimes referred to herein as a "humidified combined diluent gas stream" or "HCDGS." The proportioned AGS exiting the gas proportioner and the proportioned HCDGS exiting the humidifier are then combined in a gas mixing tube to produce the desired precision mixed gas mixture (i.e., BGP) containing the volatile analytes.

[0025] In one preferred form of the invention, the BGP is passed through sensors before exiting the gas mixer (GM) subsystem. The sensors monitor the concentrations of various constituents of the BGP. Data from the sensors is sent back to the gas proportioner, which then determines (i) the flow rate of the AGS based on the changing analyte concentrations in the AGS, and (ii) the flow rate of one or more diluent gases (e.g., O, which, when combined, will be referred to herein as the "composite diluent gas stream" or "CDGS") and which will ultimately be combined with the AGS. 2 , CO 2 and N 2) to ensure the correct composition of the BGP. Thus, in this form of the invention, the Gas Mixer (GM) subsystem provides real-time feedback control to adjust the amount of AGS and CDGS used to humidify and create the BGP in real-time to compensate for any fluctuations in the concentration of AGS being produced by the AGs, so that the final BGP has an accurate and precise concentration of gases.

[0026] In one form of the invention, a gas analyzer (GA) monitors the concentration of AGS being produced in an analyte gasifier (AG) subsystem by comparing the speed of sound through a carrier gas (e.g., helium) and the speed of sound through the AGS, which are known physical constants of the carrier gas, and the difference between these speeds is calculated and used to determine the concentration of volatile analytes in the AGS.

[0027] The output of the Gas Mixer (GM) subsystem may be used for a variety of purposes. By way of example, but not by way of limitation, when the CDGS and moisture are formulated to mimic human breath, the BGP may be used to test a high performance breath sensor. By way of further example, but not by way of limitation, when the analyte is ethanol, the BGP may be used to test a detector for identifying BrAC in a person.

[0028] In one aspect of the present invention, there is provided a system for producing a high precision mixed gas product (BGP), the system comprising: a supply of volatile analyte in liquid form; and a supply of inert carrier gas; and a supply of at least one diluent gas; and an analyte gasifier (AG) subsystem for receiving a volatile analyte in liquid form, nebulizing the volatile analyte, and mixing the nebulized volatile analyte with an inert carrier gas to form an analyte gas stream (AGS); a gas mixer (GM) subsystem for receiving the AGS from the AG subsystem and mixing the AGS with a supply of at least one diluent gas to produce the BGP, the GM subsystem comprising: a gas analyzer (GA) for receiving the AGS and analyzing the AGS; a gas proportioner for receiving the AGS from the GA, receiving at least one diluent gas, and proportioning the AGS and the at least one diluent gas based on a result of the GA to provide a proportioned AGS and a proportioned at least one diluent gas; A system is provided that includes a gas mixing chamber for receiving the proportioned AGS from the gas proportioner and the proportioned at least one diluent to produce the BGP.

[0029] In another aspect of the invention, there is provided a method for producing a high precision mixed gas product (BGP), the method comprising: a supply of volatile analyte in liquid form; and a supply of inert carrier gas; and providing a supply of at least one diluent gas; nebulizing a volatile analyte and mixing the nebulized volatile analyte with an inert carrier gas to form an analyte gas stream (AGS); and mixing the AGS with a supply of at least one diluent gas to produce BGP, the mixing step comprising: Analyzing the AGS; proportionally adjusting the AGS and the at least one diluent gas based on the results of the step of analyzing the AGS to provide a proportionally adjusted AGS and a proportionally adjusted at least one diluent gas; and mixing the proportioned AGS and the proportioned at least one diluent to produce the BGP.

[0030] In another aspect of the invention, there is provided a volatilizer for receiving a volatile analyte in liquid form, nebulizing the volatile analyte, and mixing the nebulized volatile analyte with an inert carrier gas to form an analyte gas stream (AGS), the volatilizer comprising: a first tube configured to receive a volatile analyte in liquid form, the first tube having a distal end, a proximal end, and a first portion with a lumen extending between the distal end and the proximal end, the first portion of the first tube having an outer surface that tapers inwardly in a distal direction; a second tube configured to receive an inert carrier gas, the second tube having a distal end, a proximal end, and a second portion with a lumen extending between the distal end and the proximal end, the second portion of the second tube having an inner surface that steps down from a larger diameter to a smaller diameter; the second portion of the second tube is coaxially disposed over the first portion of the first tube such that an inner surface of the second portion of the second tube is spaced from an outer surface of the first portion of the first tube; A volatilizer is provided, wherein a distal end of a first section of the first tube is positioned adjacent to a location where an inner surface of a second section of the second tube tapers in a step from a larger diameter to a smaller diameter.

[0031] These and other objects and features of the present invention will be more fully disclosed or made apparent by the following detailed description of the preferred embodiments of the invention, which should be read in conjunction with the accompanying drawings, in which like numerals refer to like parts and in which: [Brief description of the drawings]

[0032] [Figure 1]FIG. 1 is a schematic diagram illustrating a novel apparatus for producing a highly accurate mixed gas mixture containing a volatile analyte, sometimes referred to herein as a "mixed gas product" or "BGP," which comprises two subsystems: (i) an analyte gasifier (AG) subsystem that takes in a volatile analyte in liquid form, nebulizes the volatile analyte, and mixes the nebulized analyte with an inert carrier gas to produce an analyte gas stream, sometimes referred to herein as an "AGS," and (ii) a gas mixer (GM) subsystem that mixes the AGS with other gases and also humidifies the AGS to produce a desired concentration of BGP with high accuracy and precision. [Diagram 2] FIG. 1 is a schematic diagram showing a novel apparatus for producing BGP, with the analyte gasifier (AG) subsystem shown in exploded view, and also showing the gas analyzer (GA) in exploded view from the gas mixer (GM) subsystem. [Diagram 3] FIG. 1 is a schematic diagram showing in more detail the analyte gasifier (AG) subsystem, which generally includes (a) a reagent and temperature regulator module, (b) a pump module, and (c) a volatilization and expansion chamber module, and further shows the gas analyzer (GA) of the gas mixer (GM) subsystem. [Figure 4] FIG. 2 is a schematic diagram showing further details of the reagent and temperature regulator module. [Diagram 5] FIG. 2 is a schematic diagram showing further details of the pump module. [Figure 6] FIG. 2 is a schematic diagram showing further details of the vaporization and expansion chamber module, which comprises an atomizer. [Figure 7] FIG. 13 is a schematic diagram showing further details of the atomizer of the volatilization and expansion chamber module. [Figure 8] FIG. 13 is a schematic diagram showing further details of the atomizer of the volatilization and expansion chamber module. [Figure 9] FIG. 13 is a schematic diagram showing further details of the atomizer of the volatilization and expansion chamber module. [Figure 10]FIG. 2 is a schematic diagram showing further details of the GA module as well as ancillary equipment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] 1 and 2, a novel apparatus 5 is shown for generating a highly accurate mixed gas mixture containing a volatile analyte (i.e., a "mixed gas product" or "BGP"), which may be used for a variety of purposes. By way of example, but not by way of limitation, when a diluent gas and moisture are blended to mimic human breath, the BGP may be used to test a high performance breath sensor. By way of further example, but not by way of limitation, when the analyte is ethanol, the BGP may be used to test a detector for identifying a person's BrAC.

[0034] For ease of understanding, the device 5 is sometimes described below in the context of its use to generate humidified BGP that mimics human breath and whose analyte is ethanol, such as the BGP required for calibration and testing of breath-based alcohol detectors, such as those provided by the DADSS program. However, such use of the device 5 is intended to be merely exemplary and should not be construed to limit the invention to the generation of BGP that mimics human breath and / or whose analyte is ethanol. The invention is capable of generating a wide range of BGPs of various compositions and containing various volatile analytes.

[0035] The novel apparatus 5 generally comprises two subsystems: (i) an analyte gasifier (AG) subsystem 10 that takes in volatile analytes in liquid form, nebulizes the volatile analytes, and mixes the nebulized volatile analytes with an inert carrier gas to produce an analyte gas stream, sometimes referred to herein as "AGS," and (ii) a gas mixer (GM) subsystem 15 that mixes the AGS with other gases and also humidifies the AGS to produce a desired concentration of BGP with high accuracy and precision.

[0036] Analyte Gasifier (AG) Subsystem 10 The analyte gasifier (AG) subsystem 10 takes in volatile analytes in liquid form, nebulizes the volatile analytes, and mixes the nebulized volatile analytes with an inert carrier gas to produce an analyte gas stream, sometimes referred to herein as "AGS." The AGS output by the analyte gasifier (AG) subsystem 10 is delivered to a gas mixer (GM) subsystem 15 to produce the desired BGP.

[0037] 1-3, the analyte gasifier (AG) subsystem 10 generally includes (a) a reagent and temperature regulator module 20, (b) a pump module 25, and (c) a volatilization and expansion chamber module 30.

[0038] As described below, the reagent and temperature regulator module 20 is used to (i) supply the analyte (e.g., ethanol) to the pump module 25 to be nebulized in the volatilization and expansion chamber module 30, (ii) supply a seal wash fluid to the pump module 25 (see below), and (iii) regulate the temperature of the volatilization chamber (see below) of the volatilization and expansion chamber module 30. The pump module 25 supplies the analyte (e.g., ethanol) to the volatilization and expansion chamber module 30. The temperature controlled volatilization and expansion chamber module 30 receives the analyte (e.g., ethanol) in liquid form, nebulizes the analyte (e.g., ethanol), and mixes the analyte with an inert carrier gas (e.g., helium) to produce an analyte gas stream, sometimes referred to herein as "AGS."

[0039] (a) Reagent and temperature controller module 20 The reagent and temperature regulator module 20 is used to supply the analyte (e.g., ethanol) and seal wash fluid to the pump module 25, and the reagent and temperature regulator module 20 is used to control the temperature of the evaporation chamber (see below) of the evaporation and expansion chamber module 30.

[0040] The reagent and temperature regulator module 20 is shown in more detail in FIG. 4. The reagent and temperature regulator module 20 typically comprises a seal wash fluid supply 40, an analyte (e.g. ethanol) solution supply 45, and a temperature regulator 50 for controlling the temperature of the volatilization chamber (see below) of the volatilization and expansion chamber module 30. A feed line 55 of the seal wash fluid supply 40, a feed line 57 of the analyte (e.g. ethanol) solution supply 45, and a return line 60 of the seal wash fluid supply 40 are connected to the pump module 25. The feed line 55 provides the seal wash fluid to the pump module 25, and the feed line 57 provides the analyte (e.g. ethanol) to the pump module 25. Any seal wash fluid returning from the pump module 25 flows through the return line 60 into the seal wash fluid supply 40.

[0041] A temperature regulator 50 (preferably connected to a thermocouple 65 in the volatilization and expansion chamber module 30, see FIG. 6) is used to maintain the temperature of the volatilization chamber (see below) of the volatilization and expansion chamber module 30 at one or more predetermined set temperatures.

[0042] (b) Pump module 25 The pump module 25 is used to deliver the analyte (e.g., ethanol) to the temperature controlled vaporization and expansion chamber module 30. The pump module 25 is shown in more detail in FIG. 5. In one preferred embodiment of the present invention, the pump module 25 is a high performance liquid pump. More specifically, the pump used in the pump module 25 is preferably an ultra-high pressure dual piston pump. The ultra-high pressure dual piston pump is of the dual head type to reduce pulsation and ensure that a steady flow is provided to the vaporization and expansion chamber module 30. The pump module 25 includes a control 70 and a knob 75 for priming the high performance liquid pump.

[0043] To prevent pump contamination and seal failure, a seal wash fluid is used to flush the rear of the pump head. The seal wash fluid can be propanol, another organic seal wash fluid, or a non-organic seal wash fluid. The seal wash fluid enters the pump module 25 at line 80 (via the feed line 55 of the reagent and temperature regulator module 20) and exits the pump module 25 at line 85 (and returns to the seal wash fluid supply 40 via the return line 60 of the reagent and temperature regulator module 20). While flushing the rear of the pump head may not be required because the analyte (e.g., ethanol) is non-reactive with the internal structure of the pump head, this precaution is considered good practice to ensure a reliable operating system. Additionally, the presence of liquid (i.e., seal wash fluid) at the rear of the pump head helps to isolate vibrations and balance the internal operating pressures within the pump head.

[0044] The analyte (e.g., ethanol) from the reagent and temperature regulator module 20 enters the pump module 25 via line 90 (via the feed line 57 of the reagent and temperature regulator module 20) and exits the pump module 25 via line 95, where the analyte is pumped to the volatilization and expansion chamber module 30.

[0045] (c) Evaporation and Expansion Chamber Module 30 The volatilization and expansion chamber module 30 is a temperature controlled unit that receives an analyte (e.g., ethanol) in liquid form, nebulizes the analyte (e.g., ethanol), and mixes the analyte with an inert carrier gas (e.g., helium) to produce an analyte gas stream, sometimes referred to herein as "AGS." The volatilization and expansion chamber module 30 is shown in detail in Figures 6-9.

[0046] In one preferred embodiment of the present invention, the vaporizer and expansion chamber module 30 includes a nebulizer 100, an expansion chamber 105, and a vaporizer chamber 110. The vaporizer and expansion chamber module 30 may also include a regulator valve 115 and a pressure relief mechanism 120. The regulator valve 115 controls the flow rate of the AGS exiting the vaporizer and expansion chamber module 30 and proceeding to the gas mixer (GM) subsystem 15. The line 95 takes the analyte (e.g., ethanol) from the pump module 25 and conveys it to the first inlet 125 of the vaporizer 100. The carrier gas (e.g., helium) is introduced from the carrier gas supply 130 (see FIG. 1) via the carrier gas line 141 to a fitting 135 that leads to the second inlet 140 of the vaporizer 100. The line 95 and the carrier gas line 141 enter the vaporizer 100 to form a "T" junction. In the nebulizer 100, a carrier gas (e.g., helium) introduced through the second inlet 140 of the nebulizer 100 flows into a liquid analyte (e.g., ethanol) introduced through the first inlet 125 of the nebulizer 100, thereby introducing the analyte (e.g., ethanol) into the volatilization chamber 110 through the connecting fitting 142.

[0047] More specifically, looking now at Figures 7-9, which show close-up views of the nebulizer 100 of the volatilization and expansion chamber module 30, the nebulizer 100 is used to inject a stream of liquid analyte (e.g., ethanol) into a flowing carrier gas stream (e.g., helium), and the mixture of the two streams then proceeds into the temperature-controlled volatilization chamber 110. It should be appreciated that the mixing of the two streams reduces variability in the analyte (e.g., ethanol) concentration by creating a homogenized mixture of analyte (e.g., ethanol) and carrier gas (e.g., helium) before the mixture enters the volatilization chamber 110. The tip of the conduit 95 within the nebulizer 100 is sharpened to a low-angle conical tip 143 to greatly reduce the amount of surface area at the tip where the liquid analyte (e.g., ethanol) encounters the carrier gas (e.g., helium). This reduced surface area reduces capillary attachment of the liquid analyte (e.g., ethanol) to the conduit 95 (which may comprise PEEK tubing or tubing formed from another material). This conical shape, combined with the flow of accelerated carrier gas (e.g., helium) over the conical tip 143 of the tubing of conduit 95, ensures complete wicking of the liquid analyte (e.g., ethanol) droplets into the carrier gas (e.g., helium).

[0048] The introduction of the liquid analyte (e.g., ethanol) to the volatilization and expansion chamber module 30 is a critical aspect of the design. Without a smooth, pulse-free flow of the liquid analyte (e.g., ethanol) into the volatilization chamber 110, the system would not be able to achieve the level of accuracy required. To enable the system 5 to achieve the level of accuracy required, a high-precision pump is used to provide a smooth, pulse-free flow of the liquid analyte (e.g., ethanol) into the volatilization chamber 110. In one form of the invention, a high-performance dual headed pump is used in the pump module 25. More specifically, the pump used in the pump module 25 is preferably an ultra-high pressure dual piston pump. The ultra-high pressure dual piston pump can handle flow rates as low as 0.001 mL / min with a repeatability of ±0.1%. Pumping accuracy was confirmed by tests performed pumping an 80:20 IPA solution at 1000 PSI to ±2% above 0.2 mL / min. The pressure of the pumped solution was also confirmed to be ±2%. These capabilities make it possible to provide pulsation damping compensation, a standard feature of this pump.

[0049] This type of pump uses cancelling pulses through its two heads to provide a very stable flow rate. Errors in such pumps arise from the flow rate of the liquid analyte (e.g., ethanol) and the capillary properties found in low density liquids. The surface tension of a liquid is directly related to the capillary properties of that liquid. By way of example, but not by way of limitation, the intermolecular forces of ethanol are 22×10 at 25 degrees Celsius. -3 J / m 2 This gives rise to a surface tension of 72.8×10 at 20 degrees Celsius. -3 J / m 2 ), this surface tension, when combined with the adhesive forces that hold the liquid to the material that makes up the capillary (i.e., the PEEK tubing), can destroy concentration consistency.

[0050] More specifically, it was found that for the Analyte Gasifier (AG) subsystem 10 to produce a 16000 ppm effluent with an accuracy of ±29 ppm at a gas flow rate of 1 LPM, the ethanol stream must be pumped at a rate of 80 uL / min. It was found that at 80 uL / min through a 1 / 16 inch (") orifice, capillary forces are strong enough to increase the pumping profile, resulting in a visible ripple effect in the concentration of ethanol. Significantly, this was avoided by the present design, which tapers the tip of the PEEK tubing that introduces the ethanol into the center of the carrier gas (e.g., helium) stream.

[0051] Additionally, for maximum accuracy, the device must be able to easily nebulize all of the incoming analyte (e.g., ethanol) in real time. This task is accomplished by varying the inner diameter of the conduit used to carry the carrier gas (e.g., helium) to the volatilization chamber 110. When pumping a solution through a constant inner diameter conduit with a highly non-porous surface, the solution can accumulate at the sides of the chamber where the flow rate is slowest and the gas flow is most laminar. During initial testing, such anomalies were discernible when observing analyte concentrations over extended run times. To counteract this effect, the size of the carrier gas conduit was stepped down from a ¼ inch inner diameter conduit to a ⅛ inch inner diameter conduit. This ⅛ inch inner diameter conduit then exited into a chamber that was 2.5 inches in diameter. The tip of the capillary was placed at the junction between a 0.635 cm (1 / 4 inch) pipe and a 0.317 cm (1 / 8 inch) pipe to maximize wicking of any possible droplets into the gas stream due to the increased flow rate and turbulence created by passage through the orifice plate. This increased pressure (16 times higher) and flow rate (16 times higher) would then drop dramatically as the AGS entered the heated volatilization chamber. The combination of extreme temperature and a simultaneous increase in volume and dramatic drop in pressure worked in tandem to ensure proper volatilization of the liquid analyte (e.g., ethanol) to a gaseous state.

[0052] More specifically, looking now at FIG. 9, the nebulizer 100 includes: (i) the conduit 95 has an outer surface that tapers inwardly in a distal direction while the diameter of the lumen of the conduit 95 remains constant; (ii) the carrier conduit 141 has an inner surface that tapers in a stepwise manner from a larger diameter to a smaller diameter; (iii) the distal end of conduit 95 (ie, conical tip 143) is configured to be located proximate to the location where the inner surface of carrier conduit 141 tapers in a step from a larger diameter to a smaller diameter;

[0053] In this manner, the nebulizer 100 achieves complete wicking of the liquid analyte (e.g., ethanol) into the carrier gas (e.g., helium) such that all of the liquid analyte (e.g., ethanol) received from the pump module 25 is nebulized.

[0054] The volatilization chamber 110 is heated to a temperature well above the boiling point of the analyte, to ensure that all of the liquid analyte entrained in the carrier gas is volatilized. By way of example, and not by way of limitation, when the analyte is ethanol, the volatilization chamber 110 is preferably heated to approximately 90 degrees Celsius, well above the boiling point of ethanol.

[0055] The AGS then flows via pipe 144 into the expansion chamber 105 where it can be homogenized before exiting the expansion chamber 105 through pressure regulator 115 and pipe 145 into the gas mixer (GM) 15.

[0056] The pressure relief mechanism 120 is connected to the volatilization chamber 110 and is set to a relief pressure that is within the pressure limits of the system. Thus, the analyte gasifier (AG) subsystem 10 is safe in the event of an excessive pressure build-up in the analyte gasifier (AG) subsystem 10.

[0057] Gas Mixer (GM) Subsystem 15 The gas mixer 15 receives the AGS from the analyte gasifier (AG) subsystem 10 and mixes the AGS with other gases, and also humidifies the AGS, to produce the desired concentration of BGP with both high accuracy and precision.

[0058] The gas mixer (GM) subsystem 15 typically comprises: (a) a gas analyzer (GA) 146 that monitors the concentration of AGS coming from the analyte gasifier (AG) subsystem 10; (b) receiving data from a gas analyzer (GA) 146 and using this data to adjust (i) the flow rate of the AGS based on any changes in analyte concentration in the AGS, and (ii) the flow rate of one or more diluent gases (e.g., O 2 ), sometimes referred to herein as a “composite diluent gas flow” or “CDGS” that, when combined, will ultimately be combined with the AGS; 2 , CO 2 and N 2 a gas proportioner 147 for appropriately proportionally adjusting the flow rate of the gas (via a flow control valve, see FIG. 1); (c) a humidifier 148 for humidifying the proportioned CDGS exiting the gas proportioner to produce a gas stream sometimes referred to herein as a "humidified combined diluent gas stream" or "HCDGS"; (d) a gas mixing tube 149 that receives the proportioned AGS from the gas proportioner 147 and the proportioned HCDGS from the humidifier 148 to produce the desired high precision mixed gas mixture (i.e., BGP) containing the volatile analytes; (e) a sensor 150 that receives the BGP from the gas mixing tube 149 and monitors the concentrations of various constituents of the BGP. If desired, the sensor 150 may provide real-time feedback control to adjust the amount of AGS and humidified diluent gas used to create the BGP to compensate for any fluctuations in the concentration of AGS being produced by the analyte gasifier (AG) subsystem 10, so that the final BGP has a highly accurate and precise concentration of gas.

[0059] (a) Gas analyzer (GA) 146 The gas analyzer (GA) 146 receives the AGS from the analyte gasifier (GM) subsystem 10 and monitors the concentration of the analyte in the AGS. It should be noted that it is important to monitor the concentration of the analyte in the AGS because environmental and operating conditions can sometimes cause fluctuations in the concentration of the analyte in the AGS. Examples of such environmental conditions are room temperature, atmospheric pressure, etc. Examples of such operating conditions are system temperature, system pressure, etc. Data from the GA 146 is reported to the gas proportioner 180, and the AGS is sent to the gas proportioner 180. The gas analyzer (GA) 146 is shown in more detail in FIG. 10.

[0060] The gas analyzer (GA) 146 analyzes the concentration of AGS exiting the volatilization and expansion chamber module 30 in tube 145. This measurement of AGS is non-invasive and can be accurate to within a few parts per million (ppm), for example 30-300 ppm when the analyte is ethanol. In a preferred form of the invention, the gas analyzer (GA) comprises a two-component gas analyzer and has the ability to measure the ratio of two different gases. By way of example, but not by way of limitation, the gas analyzer 146 may measure the ratio of ethanol gas to helium gas. The gas analyzer 146 may use spectroscopy, chromatography, or other methods in the infrared spectrum or other electromagnetic spectrum bands known to those skilled in the art. In a preferred form of the invention, the gas analyzer 146 uses intensive and / or extensive properties to measure gas concentrations. For example, the gas analyzer 146 may use physical properties, including but not limited to measurements of temperature, pressure, thermal conductivity, flow rate, and / or speed of sound, to determine gas concentrations.

[0061] 10, system 5 may also include a filter 155 for removing impurities or particulates from carrier gas supply 130 and a flow meter 160 for determining the gas flow rate. This flow meter 160 may be, but is not limited to, a mechanical flow meter, a throttle valve, or a mass flow controller used as part of a feedback system using measurements from a gas analyzer (GA) 146. If system 5 includes filter 155, the carrier gas (e.g., helium) enters filter 155 through inlet passage 165 and exits filter 155 through outlet passage 170 before the carrier gas enters volatilization and expansion chamber module 30 via fitting 135 (see FIG. 6).

[0062] (b) Gas Proportioner 147 The gas proportioner 147 uses data from the gas analyzer (GA) 146 to adjust (i) the flow rate of the AGS based on any changes in analyte concentration in the AGS, and (ii) the flow rate of one or more diluent gases (e.g., O 2 ) that, when combined, are referred to herein as a “composite diluent gas flow” or “CDGS.” 2 , CO 2 and N 2 ) and adjust the flow rate proportionally.

[0063] In one preferred form of the invention, the gas proportioner 147 proportions the diluent gas 1 (e.g., N 2 ), a source 195 of diluent gas 2 (e.g., CO 2 ) and a source 200 of diluent gas 3 (e.g., O 2 ) from a source 205 of the diluent gas. More specifically, the gas proportioner 147 uses data received from the gas analyzer (GA) 146 to proportionate the flow of the diluent gas as needed to ultimately produce the desired mixed gas product (BGP). The gas proportioner 147 also supplies one or more proportioned diluent gases (e.g., O 2 , CO 2 and N 2) are combined into a “combined diluent gas stream” or “CDGS.” The proportioned CDGS from gas proportioner 147 is then sent to humidifier 148 via supply line 207.

[0064] At the same time, the proportioned AGS is flowed (via supply line 208) to gas mixing tube 149 (see below). 1, the gas proportioner 147 uses various flow control valves to adjust the proportions of AGS, Diluent Gas 1, Diluent Gas 2, Diluent Gas 3, etc., and CDGS. In one form of the invention, the gas proportioner 147 comprises mass flow controllers (MFCs).

[0065] (c) Humidifier 148 The humidifier 148 receives the proportioned CDGS from the gas proportioner 147 and humidifies the proportioned CDGS to provide a gas stream sometimes referred to herein as a "humidified combined diluent gas stream" or "HCDGS." To this end, the humidifier 148 receives water vapor from a humidity source 210. The HCDGS from the humidifier 148 is then delivered to the gas mixing tube 149 via supply line 220. Preferably, the humidifier 148, humidity source 210 and gas mixing tube 149 are housed in a temperature controlled chamber 225.

[0066] (d) Gas mixing tube 149 Gas mixing tube 149 receives proportioned AGS from gas proportioner 147 and proportioned HCDGS from humidifier 148. When the various components are mixed inside gas mixing tube 149, the result is a precision mixed gas mixture (i.e., BGP) containing the volatile analytes. The BGP is then delivered to sensor 150 via temperature controlled supply line 230.

[0067] (e) Sensor 150 A sensor 150 receives the BGP from the gas mixing tube 149 and analyzes the BGP, i.e., the sensor 150 monitors the concentrations of various constituents of the BGP. And, if desired, data from the sensor 150 is sent back to the gas proportioner 147 which then determines the flow rate of (i) the AGS and (ii) one or more diluent gases (e.g., O 2 , CO 2 and N 2 ) to ensure the correct composition of the BGP. Thus, in this form of the invention, the Gas Mixer (GM) subsystem 15 provides real-time feedback control to adjust the amount of AGS and CDGS used to create the BGP in real-time to compensate for any variations in the concentration of AGS being produced by the Analyte Gasifier (AG) subsystem 10, such that the final BGP has accurate and precise concentrations of gases. By way of example, but not by way of limitation, if the BGP is to mimic human breath, the sensor 150 provides the desired humidified BGP to a detector (e.g., a breath-based alcohol detector) to be calibrated and tested, adjusting in real-time the amount of AGS and CDGS used to create the BGP, such that the final BGP has concentrations of gases that mimic human breath.

[0068] It should be understood that the ultimate feedback of the device is found through integration of the device with any of a number of gas-based laboratory grade instruments for the sensor 150. Using gas-based laboratory grade instruments for additional tuning of the gas proportioner 147 can ensure that any errors in the system can be accounted for and managed as necessary.

[0069] Some advantages of the present invention The present invention provides many advantages over the prior art. In particular, the present invention: Providing a system for producing humidified organic gas analytes at low concentrations, e.g., as low as 300 ppm; Instead of using calibration standards for the analyte (e.g. when using pre-filled tanks of analyte in carrier gas), the accuracy and precision of the analyte concentration can be determined using a physical constant (i.e. the speed of sound through a gas) (e.g. for gas analyzers such as binary gas analyzers); The ratio of internal volume and capillary size is designed to atomize organics before the heating chamber, ensuring complete volatilization of analytes; May have a built-in sump to further homogenize the analyte to ensure variability from droplet formation and internal flow dynamics is mitigated; A continuous bleed valve allows the Gas Mixer (GM) subsystem to pump different amounts of analyte as needed. Generate different concentrations of analyte (e.g. ethanol) gas (0.00% BrAC to 0.325% BrAC) These analyte (e.g. ethanol) concentrations were generated at different flow rates (5.0 LPM to 35.0 LPM), Ensuring that pressure differences due to the location of the Mass Flow Controller (MFC) (i.e. at the gas proportioner) do not result in pressure differences that could affect volatilization and overall accuracy and precision; Use of a gas mixing tube that can precisely blend proportioned AGS and proportioned HCDGS to mimic human exhaled breath or specific gas mixtures of interest; Adjusting the gas ratios using a gas analyzer and gas proportioner to account for variations in the analyte gas stream (e.g. ethanol in helium); Humidify the proportioned CDGS after mixing and before the introduction of AGS, so that - Humidified breath is obtained without adversely affecting the concentration of analytes (e.g. ethanol) -Accuracy and humidification, which are usually very difficult to achieve, are both achieved. Heating the humidifier and gas mixing tubes to a desired temperature (e.g., 34 degrees Celsius) and conveying the gas mixture through heated lines to keep the gas mixture stable and prevent water from pulling the analyte (e.g., ethanol) out of the gas phase; · The output of device 5 is fed through a sensor to verify the composition of the gas mixture and allow adjustments if necessary.

[0070] Modifications of the Preferred Embodiment It will be understood that many additional changes in the details, materials, steps and arrangements of parts described and illustrated herein to explain the nature of the invention may be made by those skilled in the art and still fall within the principles and scope of the invention. Specific embodiments of the present invention are as follows. [Aspect 1] 1. A system for producing a high precision mixed gas product (BGP), the system comprising: a supply of volatile analyte in liquid form; and a supply of inert carrier gas; and a supply of at least one diluent gas; and an analyte gasifier (AG) subsystem for receiving the volatile analyte in liquid form, nebulizing the volatile analyte, and mixing the nebulized volatile analyte with the inert carrier gas to form an analyte gas stream (AGS); a gas mixer (GM) subsystem for receiving the AGS from the AG subsystem and mixing the AGS with a supply of the at least one diluent gas to produce the BGP, the GM subsystem comprising: a gas analyzer (GA) for receiving the AGS and analyzing the AGS; a gas proportioner for receiving the AGS from the GA, receiving the at least one diluent gas, and proportioning the AGS and the at least one diluent gas based on a result of the GA to provide a proportioned AGS and a proportioned at least one diluent gas; a gas mixing chamber for receiving the proportioned AGS and the proportioned at least one diluent from the gas proportioner to produce the BGP. [Aspect 2] 2. The system of embodiment 1, further comprising a temperature controlled chamber, and further wherein the gas mixing chamber is housed within the temperature controlled chamber. [Aspect 3] 2. The system of embodiment 1, wherein the volatile analyte comprises ethanol. [Aspect 4] 2. The system of embodiment 1, wherein the inert carrier gas comprises helium. [Aspect 5] 2. The system of embodiment 1, wherein the at least one diluent gas comprises three diluent gases. [Aspect 6] The three diluent gases are N 2 , CO 2 and O 2 6. The system of claim 5, comprising: [Aspect 7] 7. The system of embodiment 6, wherein the gas proportioner proportions the three diluent gases to form a composite diluent gas stream (CDGS). [Aspect 8] 8. The system of claim 7, wherein the three diluent gases in the CDGS are in a ratio similar to the ratio of the three diluent gases in human exhaled breath. [Aspect 9] 2. The system of embodiment 1, further comprising a humidifier for receiving the proportioned at least one diluent gas from the gas proportioner and humidifying the proportioned at least one diluent gas prior to passing the proportioned at least one diluent gas to the gas mixing chamber. [Aspect 10] 10. The system of embodiment 9, wherein the humidifier humidifies the proportioned at least one diluent gas to a humidity level similar to that in human exhaled breath. [Aspect 11] 10. The system of embodiment 9, further comprising a temperature controlled chamber, and wherein the gas mixing chamber and the humidifier are housed within the temperature controlled chamber. [Aspect 12] The at least one diluent gas includes three diluent gases, the three diluent gases being N 2 , CO 2 and O 2 2. The system of claim 1, further comprising: a gas proportioner that proportions the three diluent gases to form a combined diluent gas stream (CDGS), wherein the three diluent gases in the CDGS are in a ratio similar to the ratio of the three diluent gases in human exhaled breath; the system further comprising a humidifier for receiving the CDGS from the gas proportioner and humidifying the CDGS prior to passing the humidified CDGS to the gas mixing chamber; and wherein the humidifier humidifies the CDGS to a humidity level similar to the humidity level in human exhaled breath. [Aspect 13] 2. The system of embodiment 1, wherein the gas analyzer (GA) comprises a binary gas analyzer (BGA). [Aspect 14] 2. The system of embodiment 1, wherein the gas mixing chamber comprises a gas mixing tube. [Aspect 15] The system of embodiment 1, further comprising a sensor for receiving the BGP from the gas mixing chamber and analyzing the BGP. [Aspect 16] 16. The system of embodiment 15, wherein the gas proportioner is further configured to proportionately adjust the AGS and the at least one diluent gas based on sensor results. [Aspect 17] 1. A method for producing a high precision mixed gas product (BGP), the method comprising: a supply of volatile analyte in liquid form; and a supply of inert carrier gas; and providing a supply of at least one diluent gas; nebulizing the volatile analyte and mixing the nebulized volatile analyte with the inert carrier gas to form an analyte gas stream (AGS); and mixing the AGS with a supply of the at least one diluent gas to produce the BGP, the mixing step comprising: Analyzing the AGS; proportionally adjusting the AGS and the at least one diluent gas based on the results of the step of analyzing the AGS to provide a proportionally adjusted AGS and a proportionally adjusted at least one diluent gas; and mixing said proportioned AGS and said proportioned at least one diluent to produce said BGP. [Aspect 18] 20. The method of claim 17, wherein the proportioned AGS and the proportioned at least one diluent gas are mixed in a temperature controlled environment. [Aspect 19] 18. The method of embodiment 17, wherein the volatile analyte comprises ethanol. [Aspect 20] 18. The method of embodiment 17, wherein the inert carrier gas comprises helium. [Aspect 21] 18. The method of embodiment 17, wherein the at least one diluent gas comprises three diluent gases. [Aspect 22] The three diluent gases are N 2 , CO 2 and O 2 22. The method of embodiment 21, comprising: [Aspect 23] 23. The method of claim 22, wherein the three diluent gases are proportioned to form a composite diluent gas stream (CDGS). [Aspect 24] 24. The method of claim 23, wherein the three diluent gases in the CDGS are in a ratio similar to the ratio of the three diluent gases in human exhaled breath. [Aspect 25] 18. The method of embodiment 17, wherein the proportioned at least one diluent gas is humidified prior to mixing with the AGS. [Aspect 26] 26. The method of embodiment 25, wherein the proportioned at least one diluent gas is humidified to a humidity level similar to that in human exhaled breath. [Aspect 27] 26. The method of embodiment 25, wherein the humidification is performed in a temperature-controlled environment. [Aspect 28] The at least one diluent gas includes three diluent gases, the three diluent gases being N 2 , CO 2 and O 2 28. The method of claim 27, comprising: three diluent gases being proportioned to form a combined diluent gas stream (CDGS), wherein the three diluent gases in the CDGS are in a ratio similar to the ratio of the three diluent gases in human exhaled breath; the CDGS being humidified before being mixed with the proportioned AGS; and further wherein the CDGS is humidified to a humidity level similar to the humidity level in human exhaled breath. [Aspect 29] The method of embodiment 17, wherein the BGP is analyzed. [Aspect 30] 30. The method of claim 29, wherein the proportional adjustment of the AGS and the at least one diluent gas is further based on an analysis of the BGP. [Aspect 31] 1. A volatilizer for receiving a volatile analyte in liquid form, nebulizing the volatile analyte, and mixing the nebulized volatile analyte with an inert carrier gas to form an analyte gas stream (AGS), the volatilizer comprising: a first tube configured to receive the volatile analyte in liquid form, the first tube having a distal end, a proximal end, and a first portion with a lumen extending between the distal end and the proximal end, the first portion of the first tube having an outer surface that tapers inwardly in a distal direction; a second tube configured to receive the inert carrier gas, the second tube having a distal end, a proximal end, and a second portion with a lumen extending between the distal end and the proximal end, the second portion of the second tube having an inner surface that tapers in a stepped manner from a larger diameter to a smaller diameter; the second portion of the second tube is coaxially disposed over the first portion of the first tube such that the inner surface of the second portion of the second tube is spaced from the outer surface of the first portion of the first tube; a volatilizer, wherein the distal end of the first portion of the first tube is positioned adjacent to a location where the inner surface of the second portion of the second tube tapers in a step from a larger diameter to a smaller diameter.

Claims

1. 1. A system for producing a high precision mixed gas product (BGP), the system comprising: a supply of volatile analyte in liquid form; and a supply of inert carrier gas; and a supply of at least one diluent gas; and an analyte gasifier (AG) subsystem for receiving the volatile analyte in liquid form, nebulizing the volatile analyte, and mixing the nebulized volatile analyte with the inert carrier gas to form an analyte gas stream (AGS); a gas mixer (GM) subsystem for receiving the AGS from the AG subsystem and mixing the AGS with a supply of the at least one diluent gas to produce the BGP, the GM subsystem comprising: a gas analyzer (GA) for receiving the AGS and analyzing the AGS; a gas proportioner for receiving the AGS from the GA, receiving the at least one diluent gas, and proportioning the AGS and the at least one diluent gas based on a result of the GA to provide a proportioned AGS and a proportioned at least one diluent gas; a gas mixing chamber for receiving the proportioned AGS and the proportioned at least one diluent from the gas proportioner to produce the BGP.

2. The system of claim 1 further comprising a temperature controlled chamber, and further wherein said gas mixing chamber is contained within said temperature controlled chamber.

3. The system of claim 1 , wherein the volatile analyte comprises ethanol.

4. The system of claim 1 , wherein the inert carrier gas comprises helium.

5. The system of claim 1 , wherein the at least one diluent gas comprises three diluent gases.

6. The three diluent gases are N ２ , CO ２ and O ２ The system of claim 5 , comprising:

7. 7. The system of claim 6, wherein said gas proportioner proportions said three diluent gases to form a composite diluent gas stream (CDGS).

8. 8. The system of claim 7, wherein the three diluent gases in the CDGS are in a ratio similar to the ratio of the three diluent gases in human exhaled breath.

9. 2. The system of claim 1, further comprising a humidifier for receiving said proportioned at least one diluent gas from said gas proportioner and humidifying said proportioned at least one diluent gas prior to passing said proportioned at least one diluent gas to said gas mixing chamber.

10. 10. The system of claim 9, wherein the humidifier humidifies the proportioned at least one diluent gas to a humidity level similar to that in human exhaled breath.

11. 10. The system of claim 9, further comprising a temperature controlled chamber, and further wherein said gas mixing chamber and said humidifier are housed within said temperature controlled chamber.

12. The at least one diluent gas includes three diluent gases, the three diluent gases being N ２ , CO ２ and O ２ 2. The system of claim 1, wherein said gas proportioner proportions said three diluent gases to form a composite diluent gas stream (CDGS), said three diluent gases in said CDGS in a ratio similar to the ratio of said three diluent gases in human exhaled breath, said system further comprising a humidifier for receiving said CDGS from said gas proportioner and humidifying said CDGS prior to passing the humidified CDGS to said gas mixing chamber, said humidifier further humidifying said CDGS to a humidity level similar to that in human exhaled breath.

13. The system of claim 1 , wherein the gas analyzer (GA) comprises a binary gas analyzer (BGA).

14. The system of claim 1 , wherein the gas mixing chamber comprises a gas mixing tube.

15. The system of claim 1 , further comprising a sensor for receiving the BGP from the gas mixing chamber and analyzing the BGP.

16. 16. The system of claim 15, wherein the gas proportioner is further configured to proportionately adjust the AGS and the at least one diluent gas based on sensor results.

17. 1. A method for producing a high precision mixed gas product (BGP), the method comprising: a supply of volatile analyte in liquid form; and a supply of inert carrier gas; and providing a supply of at least one diluent gas; nebulizing the volatile analyte and mixing the nebulized volatile analyte with the inert carrier gas to form an analyte gas stream (AGS); and mixing said AGS with a supply of said at least one diluent gas to produce said BGP, said mixing to produce said BGP comprising: analyzing the AGS; proportionally adjusting the AGS and the at least one diluent gas based on the results of analyzing the AGS to provide a proportionally adjusted AGS and a proportionally adjusted at least one diluent gas; mixing said proportioned AGS and said proportioned at least one diluent to produce said BGP.

18. 20. The method of claim 17, wherein the proportioned AGS and the proportioned at least one diluent gas are mixed in a temperature controlled environment.

19. The method of claim 17 , wherein the volatile analyte comprises ethanol.

20. The method of claim 17 , wherein the inert carrier gas comprises helium.

21. The method of claim 17 , wherein the at least one diluent gas comprises three diluent gases.

22. The three diluent gases are N ２ , CO ２ and O ２ 22. The method of claim 21 , comprising:

23. 23. The method of claim 22, wherein the three diluent gases are proportioned to form a composite diluent gas stream (CDGS).

24. 24. The method of claim 23, wherein the three diluent gases in the CDGS are in a ratio similar to the ratio of the three diluent gases in human exhaled breath.

25. 20. The method of claim 17, wherein the proportioned at least one diluent gas is humidified prior to mixing with the AGS.

26. 26. The method of claim 25, wherein the proportioned at least one diluent gas is humidified to a humidity level similar to that in human exhaled breath.

27. 26. The method of claim 25, wherein the humidification occurs in a temperature controlled environment.

28. The at least one diluent gas includes three diluent gases, and the three diluent gases are N ２ , CO ２ and O ２ 28. The method of claim 27, comprising: the three diluent gases are proportioned to form a composite diluent gas stream (CDGS), the three diluent gases in the CDGS being in a ratio similar to the ratio of the three diluent gases in human exhaled breath, the CDGS being humidified before being mixed with the proportioned AGS, and further wherein the CDGS is humidified to a humidity level similar to the humidity level in human exhaled breath.

29. The method of claim 17, wherein the BGP is analyzed.

30. 30. The method of claim 29, wherein the proportional adjustment of the AGS and the at least one diluent gas is further based on an analysis of the BGP.

31. The system of claim 1, wherein the analyte gasifier (AG) subsystem comprises: a first tube configured to receive the volatile analyte in liquid form, the first tube having a distal end, a proximal end, and a first portion with a lumen extending between the distal end and the proximal end, the first portion of the first tube having an outer surface that tapers inwardly in a distal direction; a second tube configured to receive the inert carrier gas, the second tube having a distal end, a proximal end, and a second portion with a lumen extending between the distal end and the proximal end, the second portion of the second tube having an inner surface that tapers in a stepped manner from a larger diameter to a smaller diameter; the second portion of the second tube is coaxially disposed over the first portion of the first tube such that the inner surface of the second portion of the second tube is spaced from the outer surface of the first portion of the first tube; the distal end of the first portion of the first tube is positioned proximate to a location where the inner surface of the second portion of the second tube tapers in a stepped manner from a larger diameter to a smaller diameter.

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