Classifications

• • 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
• • 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
  • G01N33/0004—Gaseous mixtures, e.g. polluted air
  • G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
  • G01N33/0011—Sample conditioning
  • G01N33/0014—Sample conditioning by eliminating a gas
• • 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
  • G01N33/0004—Gaseous mixtures, e.g. polluted air
  • G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
  • G01N33/0027—General constructional details of gas analysers, e.g. portable test equipment concerning the detector
  • G01N33/0031—General constructional details of gas analysers, e.g. portable test equipment concerning the detector comprising two or more sensors, e.g. a sensor array
  • G01N33/0034—General constructional details of gas analysers, e.g. portable test equipment concerning the detector comprising two or more sensors, e.g. a sensor array comprising neural networks or related mathematical techniques

Definitions

• the present invention relates to a detector for a volatile signature of a substance, for example a signature of cannabis in the breath of a smoker. It also relates to a method for calibrating the detector, a method for implanting sensors therein and a method for detecting and evaluating a molecule of the substance with such a detector.
• detectors for determining the presence of a molecule or of a set of molecules in a gas mixture. Some of these detectors use specialized sensors and these sensors are sometimes for single use.
• a detector of the specialized type is, for example, a breathalyzer (or Breathalyzer ® ) which uses as sensor crystals chemically reacting with ethyl vapors included in the breath. This reaction is irreversible and the detector is for single use.
• sensors used for the detection of volatile compounds in the gas phase, for example, in the security fields to detect the presence of harmful or polluting gases, for example carbon monoxide in the air.
• Some of these sensors are semiconductors or conductive polymers. They are also used in electronic noses for the detection of aromatic compounds.
• Semiconductor sensors include a sensitive area made of a material
• the conductive polymer sensors include a sensitive zone made up of a network of conductive polymers, the measurement of which is conductivity when in contact with the gas mixture.
• Polymer sensors also have the advantage of operating at room temperature and of being very small, for example thirty two sensors over a few square millimeters.
• sensors known for the detection of volatile compounds in the gas phase which are piezoelectric crystals and surface acoustic wave resonators.
• the sample is taken, for example a perfume, which is introduced into a sampling cell.
• the sample is then analyzed simultaneously by a plurality of non-specific sensors, that is to say non-specialized in the detection of certain molecules. These sensors are of different sensitivity or types.
• the responses from these sensors are then processed to provide a signature (or fingerprint) displayed on a computer.
• the signature is then compared to signatures of reference samples to deduce the composition of the sample.
• these materials are laboratory materials, heavy, expensive and require great skill to their users.
• semiconductor sensors used in noses can be sensitive to gases in general, to propane and butane, to methane to propane and toane, to organic solvents (alcohol, toluene, xylene ...), and the a sensor's semiconductor material can form a plane or a tube.
• One parameter is the response time necessary for an optimal response of the sensor from a stable prime state, the baseline, and linked to an adsorption time.
• the baseline is the value of the resistance of the sensor placed in a gas mixture considered to be neutral, for example air in the pure state.
• Another parameter is a reconditioning time for the sensor, ie its return to its baseline after the analysis.
• Another parameter is still a risk of saturation of the sensors if the concentration of adsorbable molecules is too high.
• the precision of the operating temperature and the precision in the realization of the sensor also have a notable influence on the quality of the analysis.
• Cannabis is thus a tracer for the detection of users of drugs other than cannabis, especially since the persistence in the body of compounds derived from the consumption of cannabis is several days.
• the object of the invention is therefore to propose a device which is simple to use and maintain, reliable, inexpensive, and which can be reduced in size if necessary, for assessing the presence and / or concentration of a substance. in a breath, of a man or another animal, without the disadvantages previously mentioned.
• a detector is used which comprises:
• Such a detector makes it possible in particular to detect a substance previously inhaled by the animal, for example by a human being while smoking.
• the detector may further include means for filtering the breath.
• these means for filtering can make it possible to eliminate from the breath a large part, or all, of certain gases or certain molecules which could disturb detection or mask the desired signature.
• a detector according to the invention comprises a number of sensors between 4 and 25. This number varies according to the type of sensors used and according to the type of signature sought. We can thus use, among sensors, some of which a sensitive zone mainly comprises a semiconductor substance and / or others whose sensitive zone mainly comprises a conductive polymer.
• the memory used to keep the calibration coefficients will preferably be included in an electronic memory which can be changed simultaneously with the plurality of sensors. For sensors whose cost is high, it may be preferable to change only one or certain sensors of the plurality, to carry out a new calibration and to modify the coefficients of the memory. It may also be necessary to periodically calibrate a plurality of sensors whose certain characteristics vary as a function of time, and if the cost of this plurality justifies a periodic calibration rather than a change by a new plurality.
• a detector according to the invention can be designed to detect the signature of an alcoholic substance or a substance derived from cannabis. It can also be designed to discriminate and recognize the signatures of several substances, simultaneously or not. It can also be portable.
• a method for calibrating a detector according to the invention comprises the following steps:
• - a memory is associated with the plurality of sensors
• FIG. 1 is a schematic and simplified representation of possible steps for the development and use of a detector according to the invention
• FIG. 2 is a representation of sensor responses projected along two axes after a principal component analysis.
• the detector D is provided for detecting the signature of one or more SDD substances to be detected.
• the development of such a detector begins in the LB laboratory.
• the first step is to determine a field of action for the detector.
• it is planned to control the consumption by car drivers of substances liable to modify their driving behavior, for example alcohol and cannabis.
• cannabis is consumed in association with tobacco; it is therefore important to distinguish tobacco users only from those who have used cannabis.
• substances S.1 -Sz comprising several types of alcohol, several types of tobacco, several types of cannabis and other associated substances, to discriminate the signature of an alcohol or a cannabis.
• Other parameters can also influence the analysis, in particular, the atmosphere A breathed by the conductor P, ie the ambient air, but also the body of the conductor itself.
• An important parameter is also the variability in the sensors used.
• Figure 2 is a; representation with principal component analysis, ie a plan projection of a space comprising a greater number of dimensions.
• a detector comprising n sensors
• a different axis is assigned to a representation of the responses of each of the n sensors.
• the set of these n axes defines an n-dimensional space in which a response of the detector during a detection is represented by coordinates which are the individual responses of the t sensors for this same detection.
• Two axes are then chosen in this space so that the detector response projections on each of these axes exhibit maximum dispersion. Projections of the detector responses, in the plane defined by these two axes, form a representation as a main component.
• simultaneous responses of sensors form, for variable parameters, point clouds.
• the coordinates resulting from the responses of the sensors define groups of substantially distinct measurements for gas mixtures to be discriminated.
• the points are mainly grouped into three clouds G1, G2, G3.
• the cloud G1 corresponds to the analysis of a gaseous mixture MG which consists only of air; this is the baseline.
• Cloud G2 corresponds to the analysis of air containing tobacco smoke only.
• Cloud G3 corresponds to the analysis of air containing cannabis fumes mixed with tobacco and whose relative humidity is kept below 20%.
• each of these pluralities is put in the presence of breaths coming from different subjects P1 -Px having breathed different atmospheres A1 -Ay and consuming different substances or different mixtures of substances among the substances S1 -Sz to be detected.
• the subjects may be natural persons for substances to be detected S1 -Sz which do not pose a risk to the health of these persons or else machines, for example smoking machines.
• This database must allow the calibration of any plurality PC of sensors CT1, CT2, CT3 intended to equip the detector D.
• An MC capture module intended to equip the detector is manufactured in a UF manufacturing unit.
• the three sensors CT1, CT2, CT3 are types T1, T2, T3 respectively.
• the respective size of each of the sensors is determined, that is to say that with the calibration means MK, the response of each of the sensors is observed respectively to a known and chosen stress to calibrate it.
• the substances that can be evaluated are alcohol and cannabis.
• the electronic memory is therefore integrated jointly with the plurality PC of the sensors within the detection module MD.
• the module is then installed in the detector D, either during the manufacture of the detector, or in replacement of a previous detection module.
• the MC module is changeable. It can be changed when a sensor is defective or if you want to be able to evaluate new SE substances.
• the coefficients K being strictly linked to a given plurality of sensors PC and to evaluable substances SE given it is necessary to change the module MC as a whole. That is to say to simultaneously change all of the CT1, CT2, CT3 sensors and the associated ME memory.
• the detector D When the detector D is used by an operator OP, for example a law enforcement officer, he chooses one or more substances to be evaluated SEE, for example cannabis, among the substances evaluable SE, it is to say alcohol and cannabis. He also chooses level N, corresponding to a concentration of cannabis in the body of the controlled driver P, beyond which driving is dangerous, that is cannabis intoxication, and beyond which the driver will be presumed to contravene a safety rule.
• SEE substance to be evaluated
• level N corresponding to a concentration of cannabis in the body of the controlled driver P, beyond which driving is dangerous, that is cannabis intoxication, and beyond which the driver will be presumed to contravene a safety rule.
• the operator OP takes breath MG from the conductor P using sampling means MP. This breath is then filtered by a filter F to remove the excess water vapor, before being brought into contact with the sensors CT1, CT2, CT3. This filter can be a molecular sieve. On contact with the breath, the sensors CT1, CT2, CT3 respectively emit responses R1, R2, R3. These responses are processed by a processing unit T in combination with the coefficients K of the memory ME and the choices of the substance to be evaluated SEE and of the level N. The processing unit deduces an evaluation E which is transmitted to means display V for the operator OP.
• a detector according to the invention is also not limited to the detection of cannabis or alcoholic intoxication. It can be used to detect pollutants in the atmosphere using types of non-specialized sensors that have learned to recognize these pollutants. Instead of sensors having a high variability, it is also possible to use sensors whose manufacturing characteristics are very stable if the manufacturing cost is acceptable in view of the desired use.
• the number of sensors of the same plurality can be less than or more than three. In particular in the case of the use of polymer sensors it is preferable to have a larger number of sensors.
• the number of sensors can also be a function of the number of substances to be discriminated against or of a substance having a less legible signature among other substances.

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• Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
• Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
• Investigating Or Analysing Biological Materials (AREA)

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• 2001
  • 2001-03-27 FR FR0104079A patent/FR2822952B1/fr not_active Expired - Fee Related
• 2002
  • 2002-03-27 EP EP02753737A patent/EP1373884A2/de not_active Withdrawn
  • 2002-03-27 WO PCT/FR2002/001065 patent/WO2002077636A2/fr not_active Ceased
  • 2002-03-27 US US10/473,125 patent/US7096714B2/en not_active Expired - Fee Related
  • 2002-03-27 AU AU2002308033A patent/AU2002308033A1/en not_active Abandoned
  • 2002-03-27 CA CA2442506A patent/CA2442506C/fr not_active Expired - Fee Related

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