US3818899A - Breath testing system with increased sensitivity - Google Patents
Breath testing system with increased sensitivity Download PDFInfo
- Publication number
- US3818899A US3818899A US00268340A US26834072A US3818899A US 3818899 A US3818899 A US 3818899A US 00268340 A US00268340 A US 00268340A US 26834072 A US26834072 A US 26834072A US 3818899 A US3818899 A US 3818899A
- Authority
- US
- United States
- Prior art keywords
- breath
- alcohol
- chamber
- temperature
- sample
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
- G01N27/14—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of an electrically-heated body in dependence upon change of temperature
- G01N27/16—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of an electrically-heated body in dependence upon change of temperature caused by burning or catalytic oxidation of surrounding material to be tested, e.g. of gas
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
- G01N33/483—Physical analysis of biological material
- G01N33/497—Physical analysis of biological material of gaseous biological material, e.g. breath
- G01N33/4972—Determining alcohol content
Definitions
- the alcohol constituent oxidizes as the molecules contact the catalytic material, and as a References cued result of the oxidation reaction the temperature in UNITED STATES PATENTS creases in an amount directly proportional not only to 1,992,747 2/1935 Gilliland et al. 340/237 R the alcohol concentration but also to the catalytic 2,114,401 4/1938 Price 340/237 R area/mass ratio.
- a temperature-sensing device such as 2 .128 /194!
- Miller 23/232 E a thermistor, responds to the temperature change and 2,244,366 J3, CObSOH et 3
- the catalytic element forms one leg of a normally-balanced wheatstone bridge which unbalances, when the resistance of that element changes as a result of oxidation of breath alcohol, the degree of unbalance being proportional to the alcohol concentration.
- the heated catalyst resistance element is a platinum wire which constitutes a catalyst as well as a thermistor, namely a resistor whose resistance varies with temperature. The required heating is accomplished by constantly flowing quiescent or steadystate current through the platinum wire.
- the molecules of the breath sample must come incontact with the platinum wire to react and cause the temperature of the wire to increase. However, since the surface area of the wire is relatively small, a small number of molecules will contact it.
- the temperature and resistance of the wire will therefore increase very little in the presence of alcohol, resulting in an alcohol detector of low sensitivity.
- the detector includes a combination heater-thermistor element around which is wrapped a head or sleeve formed of some catalytic material.
- the surface area of the bead is much larger than that of the platinum wire so that considerably greater contact will be made with the molecules of the breath sample, anda greatertemperature and resistance increase will occur for a given alcohol concentration as compared to the case of the-platinum wire.
- an alcohol-oxidizing means which includes a maze of substrate elements each coated with a catalytic material to obtain a relatively'high ratio of total catalytic surface area to total mass or weight. This will maximize the number of molecules, of any gas sample passed through the maze, that will come in contact withthe catalytic material.
- Breath receiving apparatus provides a sample of breath received from a person to be tested. There are means for supplying the breath sample to the heated chamber and through the maze where any alcohol present in the sample oxidizes.
- the breath testing system of the invention determines the breath alcohol concentration of a person and comprises means for providing a heated chamber, within which is disposed a temperature-sensing device, such as a thermistor, having a predetermined charac- FIGURE of which is a diagram,partly in block form and partly in schematic, of a breathtesting system constructed in accordance with one embodiment of the invention.
- the DESCRIPTION OF THE ILLUSTRATED EMBODIMENT Breath receiving apparatus 10 develops a measured sample of breath received from a subject under test.
- the apparatus may takeany suitable construction to facilitate the receipt of breath blown or exhaled by the person and to deliver a sample of that breath to the outlet of the apparatus, theunused breath being vented or dumped to the atmosphere.
- One example of an appropriate form for apparatus 10 is found in copending application Ser. No. 136,778, filed Apr. 23, 1971 the names of Donald W. Collier, Joseph P. Hoppesch and Anthony C. Mamo, and issued Oct. 9, 1973 as US. Pat. No. 3,764,270.
- apparatus 10 preferably includes appropriate control equipment to make certain that the breath sample constitutes deep lung breath. Suitable control equipment to perform that function is also illustrated and described in the aforementioned copending application Ser. No. 136,778. There, a breath sample is not produced at the outlet of the breath receiving apparatus until a continuous uninterrupted breath flow has occurred for a predetermined time period, such as 5 seconds. A sample taken at the end of a 5-second interval of uninterrupted blowing or exhaling constitutes deep lung breath, from which an accurate reading of alcohol level may be obtained as is well known in the art.
- each breath sample from apparatus is channeled to one end of a tubular or cylindrical shaped enclosure 15, made for example of glass or plastic, the other end of which opens to the atmosphere.
- a flat sep arating wall 16, which may also be constructed of glass or plastic, divides cylindrical tube into two halves to provide two chambers 17, 18 of equal volume. With this construction, a breath sample emanating at the outlet of apparatus 10 is split by wall 16 into two equal portions, one of which flows through chamber 17 and then to the atmosphere via the open end of tube 15, while the other portion simultaneously flows through chamber 18 and thence to the atmosphere.
- Each chamber which is heated in a manner to be explained, contains a temperature-sensing device for measuring or recording the temperature within the chamber.
- These devices labeled 21 and 22, have predetermined characteristics or properties that vary with temperature.
- devices 21 and 22 are identical thermistors whose resistances vary in response to temperature variations.
- Thermistors 21 and 22 are included in and form part of a normally-balanced, four-legged wheatstone bridge. Specifically, thermistors 21 and 22 constitute respective ones of two adjacent legs of the bridge circuit. A pair of simple, equal size resistors 25 and 26 function as the other two adjacent legs. Bridge junction 27 connects to the positive terminal 28 of a source of DC. operating potential, while junction 29 is connected to the negative terminal 31 of that potential source. Direct current therefore flows continuously from positive terminal 28 to negative terminal 31 through two parallel paths one provided by legs 21 and 22 and the other by legs 25 and 26.
- the constant current flow through devices 21 and 22 produces heat to heat chambers 17 and 18.
- the required heating of chambers 17 and 18 is accomplished by a separate cylindrical shaped heater 34 which forms a jacket around the outside of tube 15. Heater 34 may, for example, be a heating coil through which current passes.
- thermistors 21 and 22 normally have the same resistance and, since resistors 25 and 26 are of equal electrical size, in the absence of any external stimulation the bridge circuit will be balanced and junctions 32 and .33 will be established at identical voltage levels.
- the output of alcohol detector 13 is derived between junctions 33 and 32 and with a zero voltage difference existing between those junctions no output signal will be developed by alcohol detector 13.
- the output signal will also have zero amplitude when a breath sample, containing no alcohol, is delivered to heated chambers 17 and 18 from apparatus 10. The alcohol-free breath will flow through those chambers and to the atmosphere without causing any chemical reaction and/or temperature change. Detector 13 will be unresponsive to the breath sample.
- a very small amount of breath alcohol will upset or unbalance the bridge circuit to produce an output signal having a finite amplitude precisely representing the alcohol concentration.
- alcohol detector 13 is extremely sensitive to the presence of breath alcohol and a very small change in alcohol concentration results in a measurable change in the amplitude of the output signal to provide a read-out which accurately depicts the alcohol level. This is accomplished by causing the temperature in chamber 17 to vary to a substantial extent in response to the slightest change in breath alcohol concentration.
- a maze or bulk of substrate elements is included in each of chambers 17 and 18.
- the fibers are sufficiently loosely packed into each chamber to pennit breath flow through the entire length of tube 15.
- Each of the substrate elements or fibers of the maze (labeled 35) in chamber 17 is coated with a catalytic material, while the maze 36 of substrate elements in chamber 18 remains uncoated.
- maze 35 serves as an alcohol-oxidizing means since any alcohol in the breath sample flowing through chamber 17 oxidizes as it contacts the catalytic material.
- the catalyst coated substrate elements should also have a thermal capacitance as low as possible since the temperature increase is inversely proportional to the thermal capacitance.
- Temperature-sensing device 21 increases in resistance in response to the temperature increase and to an extent directly proportional to the alcohol level. Meanwhile, the non-catalytic maze 36 in chamber 18 is unresponsive to the alcohol in' the breath flowing through that chamber and thus the resistance of device 22 remains unchanged. With unequal resistances for thermistors 21 and 22, the bridge circuit becomes unbalanced as the voltage drops in those thermistors will be unequal and this causes junction 32 to be established at a voltage different than that at junction 33. The magnitude of the differential represents the degree of unbalance and the particular alcohol level in the breath sampled.
- the output information signal, produced between junctions 33 and 32 and applied to output utilizing apparatus 39 therefore has an amplitude directly proportional to and representing the breath alcohol concentration.
- Output utilizing apparatus 39 may include a meter which effectively measures the information signal amplitude, thereby providing a visual display of the alcohol concentration in the tested breath sample.
- the output apparatus can be a simple bulb energized when the infonnation signal exceeds a predetermined threshold amplitude level.
- Apparatus 39 maytake any of a variety of different fonns inasmuch as there are many devices that can be controlled by an electrical signal whose amplitude signifies the alcohol level of a persons breath.
- an amplifier may be interposed between alcohol detector 13 and apparatus 39 so that the information signal may be amplified before it is applied to the output utilizing apparatus.
- No amplifier is illustrated in order to simplify the drawing as much as possible.
- the invention need not be embodied in a bridge type alcohol detector, but may be incorporated in any alcohol detector of the type having acatalyst which oxidizes breath alcohol and produces a temperature changeto in turn effect the development of an output information signal reflecting the alcohol content.
- the detector may merely comprise a single thermistor through which direct current continuously flows and around which a breath sample flows through admir of catalyst coated substrate elements to produce an oxidation reaction to vary the temperature of the thermistor thereby varying the current therethrough.
- the detector's output signal would be determined by the current flowing through the thermistor.
- the advantages of the present invention are combined with those achieved in a conventional bridge type detector.
- the adjacent legs provided by devices 21 and 22 are (with the sole exception of the catalytic material in chamber 35) located in identical environments, are identical in construction and are simultaneously exposed to the same breath sample, any change in either one of those legs caused by thermoconductivity, convection, etc., will be balanced out by an equal and compensating change in the other leg.
- current changes due to power supply variations are also cancelled out.
- the invention could be incorporated in an AC bridge rather than the DC bridge illustrated.
- the invention provides, therefore, an improved breath alcohol detection system of the catalytic oxidation or combustion type that achieves a substantially greater sensitivity to alcohol content than previously possible in similar type breath analyzers. This is accomplished by utilizing a maze of catalyst covered substrate elements to increase the area contact between the gas molecules and the catalyst.
- a breath testing system for determining the breath alcohol concentration of a person comprising:
- alcohol-oxidizing means within said chamber and including a maze of substrate elements, formed of glass wool fibers having a relatively low thermal capacitance, each of which elements is coated with a catalytic material to obtain a relatively high ratio of total catalytic surface area to total mass and to maximize the number of molecules, of any gas sample passed through said maze, that will come in contact with the catalytic material;
- breath receiving apparatus for providing a sample of breath received from a person to be tested
Abstract
Description
Claims (1)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US00268340A US3818899A (en) | 1972-07-03 | 1972-07-03 | Breath testing system with increased sensitivity |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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US00268340A US3818899A (en) | 1972-07-03 | 1972-07-03 | Breath testing system with increased sensitivity |
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US3818899A true US3818899A (en) | 1974-06-25 |
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US00268340A Expired - Lifetime US3818899A (en) | 1972-07-03 | 1972-07-03 | Breath testing system with increased sensitivity |
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Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4017792A (en) * | 1974-09-05 | 1977-04-12 | Dragerwerk Aktiengesellschaft | Device for determining and/or measuring alcohol content in a gas and method of manufacturing a semi-conductor body for use in alcohol detection |
US4607719A (en) * | 1983-12-21 | 1986-08-26 | Drummond And Relph Limited | Alcohol detection device |
US20040009605A1 (en) * | 1999-06-30 | 2004-01-15 | U.S. As Represented By The Administrator Of The National Aeronautics & Space Administration | Method for the detection of volatile organic compounds using a catalytic oxidation sensor |
CN100585374C (en) * | 2005-01-27 | 2010-01-27 | 中国科学院大连化学物理研究所 | The gas sampling method of alcohol detector in a kind of breathing gas |
US20110283770A1 (en) * | 2009-02-10 | 2011-11-24 | Hok Instrument Ab | Breath analysis |
US20120115240A1 (en) * | 2010-11-10 | 2012-05-10 | Searete Llc, A Limited Liability Corporation Of The State Of Delaware | Treatment of ruminant exhalations |
GB2532480A (en) * | 2014-11-20 | 2016-05-25 | Autoliv Dev | A breath analyser device |
Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1992747A (en) * | 1931-09-14 | 1935-02-26 | Mine Safety Applianees Company | Method of and apparatus for quantitative gas analysis |
GB464798A (en) * | 1934-11-19 | 1937-04-26 | Heinz Berger | Portable apparatus for automatically detecting, signalling and stopping gas leakages rom gas conduits and containers |
US2114401A (en) * | 1936-07-15 | 1938-04-19 | Mine Safety Appliances Co | Gas testing |
US2234128A (en) * | 1938-11-25 | 1941-03-04 | Cities Service Oil Co | Analysis of gas |
US2244366A (en) * | 1937-11-24 | 1941-06-03 | Mine Safety Appliances Co | Combustible gas indicator |
US2683793A (en) * | 1951-03-15 | 1954-07-13 | Benjamin Cooper | Heating circuit for reaction cells |
US3147465A (en) * | 1960-12-27 | 1964-09-01 | Mine Safety Appliances Co | Methane alarm and control system |
US3239828A (en) * | 1962-07-27 | 1966-03-08 | Erdco Eng Corp | Combustible gas detector |
US3600134A (en) * | 1968-04-11 | 1971-08-17 | Corning Glass Works | Method for the determination of alcohol and other oxidizable organic compounds in respired air and body fluids |
-
1972
- 1972-07-03 US US00268340A patent/US3818899A/en not_active Expired - Lifetime
Patent Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1992747A (en) * | 1931-09-14 | 1935-02-26 | Mine Safety Applianees Company | Method of and apparatus for quantitative gas analysis |
GB464798A (en) * | 1934-11-19 | 1937-04-26 | Heinz Berger | Portable apparatus for automatically detecting, signalling and stopping gas leakages rom gas conduits and containers |
US2114401A (en) * | 1936-07-15 | 1938-04-19 | Mine Safety Appliances Co | Gas testing |
US2244366A (en) * | 1937-11-24 | 1941-06-03 | Mine Safety Appliances Co | Combustible gas indicator |
US2234128A (en) * | 1938-11-25 | 1941-03-04 | Cities Service Oil Co | Analysis of gas |
US2683793A (en) * | 1951-03-15 | 1954-07-13 | Benjamin Cooper | Heating circuit for reaction cells |
US3147465A (en) * | 1960-12-27 | 1964-09-01 | Mine Safety Appliances Co | Methane alarm and control system |
US3239828A (en) * | 1962-07-27 | 1966-03-08 | Erdco Eng Corp | Combustible gas detector |
US3600134A (en) * | 1968-04-11 | 1971-08-17 | Corning Glass Works | Method for the determination of alcohol and other oxidizable organic compounds in respired air and body fluids |
Cited By (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4017792A (en) * | 1974-09-05 | 1977-04-12 | Dragerwerk Aktiengesellschaft | Device for determining and/or measuring alcohol content in a gas and method of manufacturing a semi-conductor body for use in alcohol detection |
US4607719A (en) * | 1983-12-21 | 1986-08-26 | Drummond And Relph Limited | Alcohol detection device |
US20040009605A1 (en) * | 1999-06-30 | 2004-01-15 | U.S. As Represented By The Administrator Of The National Aeronautics & Space Administration | Method for the detection of volatile organic compounds using a catalytic oxidation sensor |
CN100585374C (en) * | 2005-01-27 | 2010-01-27 | 中国科学院大连化学物理研究所 | The gas sampling method of alcohol detector in a kind of breathing gas |
US20110283770A1 (en) * | 2009-02-10 | 2011-11-24 | Hok Instrument Ab | Breath analysis |
US20120115240A1 (en) * | 2010-11-10 | 2012-05-10 | Searete Llc, A Limited Liability Corporation Of The State Of Delaware | Treatment of ruminant exhalations |
US8673219B2 (en) * | 2010-11-10 | 2014-03-18 | Invention Science Fund I | Nasal passage insertion device for treatment of ruminant exhalations |
US9199193B2 (en) | 2010-11-10 | 2015-12-01 | The Invention Science Fund I, Llc | Treatment of ruminant exhalations |
GB2532480A (en) * | 2014-11-20 | 2016-05-25 | Autoliv Dev | A breath analyser device |
US9366665B1 (en) | 2014-11-20 | 2016-06-14 | Autoliv Development Ab | Breath analyzer device |
GB2532480B (en) * | 2014-11-20 | 2019-06-05 | Veoneer Sweden Ab | A breath analyser device |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: 677491 ONTARIO, LTD., 1765 SHAWSON DRIVE, MISSISSA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:ALCOHOL COUNTERMEASURE SYSTEMS INC.;REEL/FRAME:004611/0156 Effective date: 19860815 Owner name: 677491 ONTARIO, LTD., 1765 SHAWSON DRIVE, MISSISSA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:ALCOHOL COUNTERMEASURE SYSTEMS INC.;REEL/FRAME:004611/0156 Effective date: 19860815 |
|
AS | Assignment |
Owner name: ALCOHOL COUNTERMEASURE SYSTEMS CORP. Free format text: CHANGE OF NAME;ASSIGNOR:677491 ONTARIO, LTD.;REEL/FRAME:004701/0946 Effective date: 19861209 Owner name: ALCOHOL COUNTERMEASURE SYSTEMS CORP.,STATELESS Free format text: CHANGE OF NAME;ASSIGNOR:677491 ONTARIO, LTD.;REEL/FRAME:004701/0946 Effective date: 19861209 |