WO2014111611A1 - Method for analysis of a gas and artificial nose - Google Patents

Method for analysis of a gas and artificial nose Download PDF

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Publication number
WO2014111611A1
WO2014111611A1 PCT/ES2014/070025 ES2014070025W WO2014111611A1 WO 2014111611 A1 WO2014111611 A1 WO 2014111611A1 ES 2014070025 W ES2014070025 W ES 2014070025W WO 2014111611 A1 WO2014111611 A1 WO 2014111611A1
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Prior art keywords
sensor
parameter
artificial nose
nose
modulation
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PCT/ES2014/070025
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Spanish (es)
French (fr)
Inventor
David Jesús YAÑEZ VILLARREAL
Francisco DE BORJA RODRÍGUEZ ORTIZ
Eduardo SERRANO JEREZ
Pablo VARONA MARTÍNEZ
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Sgenia Soluciones, S.L.
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Publication of WO2014111611A1 publication Critical patent/WO2014111611A1/en

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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
    • G01N33/0004—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
    • 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
    • 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

Definitions

  • the present invention relates to a method of analyzing a gas by means of an artificial nose and a bio-inspired artificial nose of general application, which uses adaptive modulation strategies of the sensor parameters directed by the objective given to the nose.
  • the incorporation of said strategies gives the artificial nose of the invention reduced dimensions, therefore, high portability, a wide range of applicability and a reduced production cost.
  • Electronic noses are machines designed to accurately detect and discriminate odors.
  • a generally accepted definition of an artificial olfactory system was given by Gardner and Bartlett in 1994 (Oxford Press): "instrument comprising a grouping of chemical sensors with partially overlapping sensitivities together with a pattern recognition system, capable of analyzing and recognizing aromas simple or complex. "
  • the detection module includes the sensors responsible for directly or indirectly translating the presence of a smell into signals electric. When they come into contact with volatile components present in the gas, the sensors react, experiencing a physical change in their properties. The sensor response is received in the electronic module, which transforms the signal into a digital value. The values are analyzed below in the processing module, which is responsible for recognizing and / or classifying the recorded signals.
  • the method of operation of an artificial nose comprises a learning or training stage, in which the artificial nose is subjected to the analysis of a series of recognized samples to construct reference models. At a later stage of odor acquisition, the artificial nose is able to recognize new samples from the reference models.
  • olfactory sensors There are many types of olfactory sensors based on different physical principles: chemoresistive, chemocapacitive, potentiometric, gravimetric, optical, acoustic, thermal, polymeric, ammeter, chromatographic, spectrometric, field effect, etc.
  • Chemosensitive sensors are the most widespread due to their small size and easy integration into an electrical circuit.
  • matrices are used that combine sensors of this type, which offer certain advantageous characteristics, based on the design of a commercial electronic nose.
  • sensor arrays or multisensor components also have clear economic disadvantages, reliability, stability over time and miniaturization. DESCRIPTION OF THE INVENTION
  • a method of analyzing a gas by means of an artificial nose comprising at least one sensor comprising: (a) detecting by means of at least one sensor a sample of the gas to be analyzed, and
  • the adaptive modulation of at least one parameter is performed by a feedback function that modifies at least one parameter that affects the operating mode of the sensor.
  • the efficiency measure is determined from the comparison of the signal obtained from the detection with at least a second signal.
  • the second signal may be a theoretical or reference signal, or it may be a second signal obtained by detection.
  • the efficiency measure is determined from the comparison of the signal obtained from the detection with at least one threshold value.
  • the modulation of at least one parameter can be performed based on measures of efficiency of recognition of odors and / or discrimination of odors and / or classification of odors and / or in a learning stage.
  • the adaptive modulation of the parameters can be discrete (responding to specific events detected in the acquisition of the signal), or continuous (during the entire acquisition process).
  • the activation of the modulation starts automatically depending on the task assigned to the nose.
  • the modulation of the parameters is preferably activated when it is determined that a smell is not identified with the current sensor parameters.
  • the modulation of the parameters is preferably activated when it is determined that the signal of an odorant does not provide sufficient discriminant characteristics with the current parameters of the sensor.
  • Typical events that define the need to start a new modulation are the saturation of the signal or the arrival at a steady state of the same when the objective of the task assigned to the nose has not yet been achieved.
  • the timing of these events in general is not known a priori, and is determined by the comparison with the efficiency measure.
  • Adaptive modulation of at least one parameter can be performed during one stage of training the artificial nose or during the stage of acquisition of the smell by the artificial nose.
  • the parameter to be modulated is the gas flow rate that affects the sensor and / or the heating temperature.
  • the parameters to be modulated are selected according to the type of sensor, which can be any olfactory sensor.
  • two parameters that can be adaptively modulated are the heating temperature of the sensor and the gas flow that affects the sensor (sniffing).
  • the flow rate, the incident wavelength on the sensitive surface and the optical path length can be adaptively modulated.
  • the flow rate and amplitude (in voltage and intensity) of the frequency signal used are susceptible to adaptively modulating to determine the electrical capacity of the sensor.
  • QCM gravimetric sensors quartz crystal micro balance
  • the flow and base resonance frequency of the assembly can be varied by adaptively modulating Young's module with a piezoelectric prestressing.
  • SAW gravimetric sensors Surface acoustic wave
  • the flow rate and the type of pulse that propagates square, sine wave, ramp Certainly can be adaptively modulated.
  • Potentiometric sensors can adaptively modulate the flow and working pressure in order to vary in a controlled way the partial pressure of the gas in the solution.
  • an artificial nose comprising:
  • the artificial nose according to the second inventive aspect is adapted to perform the method according to the first inventive aspect and its different embodiments.
  • the artificial nose of the invention can be based on a single sensor, adapted to work in different regimes obtained from the application of strategies consisting of the adaptive modulation of at least one parameter that affects the operation and, consequently, the sensitivity of the sensor.
  • the artificial nose of the invention has dimensions and weight much lower than the olfactory devices considered portable in the market, so it can be considered ultraportable.
  • the senor consists of a single sensitive surface.
  • the processing means comprise a microcontroller, a PC or a PLC (programmable logic controller).
  • the introduction of adaptive modulation strategies in the learning or training stage and / or during the acquisition of the smell results in a more versatile artificial nose than the state of the art, by expanding the range of sensitivities with respect to artificial noses based on non-matrix sensors.
  • its use is allowed in electronic noses of general application, obtaining capacities for detecting and separating aromas analogous and even higher than those obtained in systems based on a matrix of sensors of greater cost and size.
  • the artificial nose and the method of the invention have clear competitive advantages, related both to its low production cost and its robustness, in addition to a substantial simplification of the electronics responsible for amplifying, filtering and conditioning the measured signal, with which substantially reduces the size and weight of the artificial nose and increases its portability.
  • the sensor is chemo-resistive and the adaptive modulation is carried out on the incoming air flow and / or on the heating temperature, which is the temperature at which the sensor works.
  • the adaptive modulation of the flow or air flow in a manner analogous to what occurs in nature, information from the odorous particles found in the gas under analysis is enriched by introducing into it fluid dynamic complexity that affects at pressure, temperature, average free path of particles, diffusivity, etc.
  • Adaptive air flow modulation can be performed both during the learning stage and during the acquisition of the smell.
  • the range of temperature values to which the sensor's sensitive surface is subjected is regulated.
  • the variation of the heating temperature affects the concentration of odorants on the sensitive surface, its diffusivity, etc.
  • Adaptive modulation of the heating temperature of the sensor can be performed both during the learning stage and during the acquisition of the smell.
  • the present method of analysis is intended to be preferably performed on an artificial nose with a single sensor, it is also applicable in artificial noses with more than one sensor.
  • the invention allows the theoretical and operational establishment of the best adaptive modulation functions based on the objective, which can be for example the detection of a smell, the discrimination between two or more odors, the classification of one or more odors in a series of categories, the identification of an odorant in a mixture, the maintenance of the effective stability of the sensor, etc.
  • the efficiency measure determines the instants and the way of performing adaptive modulation, which takes place by relevant events that are detected in the signal in relation to the objective given to the nose. The occurrence of these events is not known a priori and, in general, they do not have to be periodic.
  • the present invention is applicable in a number of areas, including:
  • Health field infection detection, study of anosmias and early prediction of associated neurodegenerative pathologies, detection of oncological conditions, blood or biogenic fluid analysis, pathologies of the endocrine system, characterization of clinical olfactory tests, etc.
  • Robotics mobile and industrial.
  • Figure 1. Shows a schematic elevation of an artificial nose according to the invention.
  • Figure 2. Shows a schematic representation in perspective of the path made by a gas subjected to analysis in an artificial nose according to the invention.
  • Figure 3. Shows a schematic representation of the signals and control elements of an artificial nose according to the invention.
  • Figure 4. It shows a representation of (A) an array of six standard chemoresistant sensors and (B) a virtual array of sensors obtained thanks to the variation of different heating and flow temperature values.
  • Figure 5. Shows (A) a schematic representation of the flow of information between the Sensory, electronic and processing modules of an artificial nose according to the state of the art and (B) according to the present invention.
  • Figure 6. It shows two sets of signals of two different odors made by a matrix of four sensitive surfaces.
  • Figure 7. Sample (A) two readings obtained from two different odors made in different instants by the same surface without modulation and (B) the reading of these two same odors subjected to different modulation regimes at times t 2 , t 3 and t 4 . These moments are defined by the efficiency measure and in general cannot be predetermined.
  • Figure 8. Shows an example of adaptive modulation according to the invention for the task of discriminating two very similar concentrations of ethanol.
  • the artificial nose comprises a sensor (10), an electronic board (3) and a microcontroller (12) housed inside an envelope (2).
  • the envelope has a series of accesses through which the entry and / or exit of the gas to be analyzed in the artificial nose is allowed.
  • the gas is penetrated (7) into the artificial nose through a first access (4).
  • the gas inlet is forced through a fan (9), so that the gas directly affects the sensor (10).
  • the sensor (10) selected to illustrate the invention is of the chemoresistant type and has four pins, two for the supply of the heating temperature and another two for its signal output.
  • the fan responsible for pumping gas is an axial fan of small dimensions capable of generating a flow of up to 2.7m 3 / h.
  • the fan (9) is fixed to an inner wall of the enclosure (2), so that it forces the gas inlet directly on the sensor.
  • the artificial nose of the example has a second access (5), made as a set of holes (5), for the exit (8) of the gas to the outside of the nose. Additional accesses can be provided, for example a third access (6) for the output of a multi-wire cable (11) responsible for carrying the communications and electrically feeding the artificial nose.
  • the electronics have been placed inside a 50 x 35 x 17mm commercial ABS envelope (2) on whose side the passage of the power and communications cable has been facilitated with a hole.
  • the cover (1) of the envelope (2) two sets of holes have been machined for the access and exit of the gas to be analyzed.
  • the size of the gas inlet holes (4) is preferably about 0.4mm.
  • the size of the gas outlet orifices (5) is preferably about I mm.
  • the size of the hole for the communication cable (6) is preferably about 5mm in diameter.
  • the artificial nose there is a microcontrolled electronic device capable of regulating both the heating temperature and the gas flow.
  • the adaptive modulation of the heating temperature and the flow rate is carried out in this embodiment by means of two PWM type FET gate power control systems with low pass filter.
  • the device has two communication modes: a USB protocol communication module and an RS-485 module for systems Long distance multipoint
  • the processing means must be adapted for the acquisition of the signal readings and their analysis
  • the adaptive modulation of the gas flow and the heating temperature of the sensor can be controlled by the microcontroller embedded in the artificial nose or by an external PC or PLC
  • the possibility of adaptively modulating, depending on events defined by the objective given to the nose, both the gas flow and the temperature is integrated as an additional functionality in the learning algorithm and / or classification, increasing the discrimination capacity of the equipment During the analysis process both parameters can be adjusted din ically and in real time based on the state procurement in the that is the artificial nose.
  • the microcontroller (12) housed in the electronic board (3) adaptively modulates the respective activity of the heating temperature power control systems (13) of the chemoresistant sensor (10) and of the flow rate (14) of the fan (9) by means of two signals (18) regulated by pulse width (classical method of regulation and energy management typically known as PWM). It also has two communication modules (15, 16) dedicated to the transfer of information to external processing means (17).
  • PWM pulse width
  • Figure 4 shows by comparison a matrix of six real chemo-resistive sensors (af) of a state-of-the-art artificial nose (A) and the virtual sensor matrix (represented in lighter color) with different sensitivities of a artificial nose according to the invention (B), obtained from a single sensor (adaptive temperature modulation function sensor T1, flow darker represented F1), subjected to different adaptive modulation functions (Tx) of heating temperatures and to different functions of adaptive modulation (Fy) of flow or gas flow values with odorant that is passed through its surface.
  • af real chemo-resistive sensors
  • A state-of-the-art artificial nose
  • B virtual sensor matrix
  • the artificial nose of the invention is able to obtain different and partially overlapped effective sensitivities from a single sensitive surface, equivalent to the sensitivities that would be obtained using a high number of virtual sensors operating from consecutive way.
  • adaptive modulation is performed by means of a feedback function m (f) that modifies the parameters of acquisition (and / or learning and / or recognition) based on an objective efficiency function given to the nose (for example a function that measures the distance between signals).
  • the times t where modulation is effective are determined by events observed in the sensor signal and are automatically defined in relation to to the objective given to the nose.
  • the module responsible for managing the adaptive modulation of the parameter (s) is the processing module, which is able to vary these parameters in real time in an adaptive manner to optimize the detection and discrimination of the odor depending on the objective given to the nose.
  • FIG. 5A shows the sensory (21), electronic (22) and processing (23) modules together with the flow of information that occurs between them in a traditional artificial nose.
  • the sensory (24), electronic (25) and processing (26) modules are represented respectively together with the information flow and the modulation that occurs between them in the artificial nose according to the present invention.
  • Figure 6 is an example of the classic method for odor discrimination. It shows, as a function of time (t), two sets of signals (S a 1 , S b 1 , S c 1 , S d 1 ; S a 2 , S b 2 , Sc 2 , S d 2 ) for two different odors (1 and 2) made by a matrix of four sensitive surfaces (a, b, c, d).
  • the figure shows that although the signals (S C 1 , S C 2 ) obtained by the same surface are hardly distinguishable for the two odors, the other signals (S a 1 , S b 1 , S d 1 ; S a 2 , S b 2 , S d 2 ) are clearly different for the two odors, that is, three of the four sensitive surfaces provide additional information on the smell with which discrimination is possible.
  • Figure 7 A shows a graph representing two signal readings (S to 1 ; S to 2 ) obtained for two different odors as a function of time, made at different times by the same sensitive surface to keep the modulation parameters constant .
  • the two odors produce signals that are difficult to distinguish in a certain operating mode of the sensor.
  • Figure 7B shows the effect produced in the reading of signals for these two same odors, which at first (ti) are indistinguishable but subject to different regimes at instants (t 2 , t 3 , t 4 ) in those that a modulation parameter has been adaptively modified are easily distinguishable.
  • these parameters may be the heating temperature and / or the flow rate.
  • FIG. 8 An example of gas flow modulation to discriminate two very similar concentrations of ethanol is shown in Figure 8. Without modulation the nose is not able to discriminate these two concentrations.
  • S to 1 corresponds to the signal recorded by the artificial nose of the invention for 0.5% ethanol and S to 2 corresponds to the signal recorded for 0.45% ethanol.
  • Modulation m F (in this example, gas flow F) is performed until the distance d between the two signals reaches an appropriate threshold.
  • the moments in which a flow modulation is performed are indicated by arrows.
  • the panel on the left shows the signals obtained as a function of time and the panel on the right shows the instantaneous distance (d) between the signals, together with the threshold considered appropriate for discrimination (0.04V in this example).
  • the measure of process efficiency would be the distance between the two recorded signals, made as the difference between one and the other.
  • the distance between signals can be calculated in another way, so that it is not necessarily the difference between one and the other. While the distance is less than the set threshold value, modulation is performed adaptive of the gas flow incident on the sensor.
  • the lower panel shows the modulation function (m F ) used in this example, which corresponds to a function that modifies the gas flow in the appropriate direction if the discrimination threshold has not been reached in a time interval. Once the distance between the two signals has reached the established threshold, the discrimination between the two signals is considered satisfactory and the process ends.
  • modulation function m F
  • more complex functions can be used in which the modification of the parameter to be modulated is dependent on the measure of efficiency employed defined in relation to the objective given to the nose.
  • the adaptive modulation of the parameters is discrete, but in other cases it could be continuous.
  • the gas flow rate and the heating temperature have been mentioned as modulable parameters in relation to a chemoresistant sensor, it will be understood that the above explanations are equally applicable to other modulable parameters in relation to other types of olfactory sensors .

Abstract

The analysis method is performed by means of an artificial nose that comprises at least one sensor and involves detecting a sample of the gas to be analysed and adaptively modulating at least one parameter affecting the method of operation of the sensor as a function of a signal obtained from detection by the sensor and an efficiency measurement. The artificial nose comprises at least one odour sensor and processing means adapted for adaptively modulating at least one parameter affecting the operating method of the sensor as a function of a signal obtained from detection by the sensor and an efficiency measurement. The incorporation of adaptive modulation strategies means that the artificial nose of the invention is smaller and therefore more easily portable, and confers thereon a broad range of applications and reduces the production cost thereof.

Description

D E S C R I P C I Ó N  D E S C R I P C I Ó N
MÉTODO DE ANÁLISIS DE UN GAS Y NARIZ ARTIFICIAL OBJETO DE LA INVENCIÓN METHOD OF ANALYSIS OF A GAS AND ARTIFICIAL NOSE OBJECT OF THE INVENTION
La presente invención se refiere a un método de análisis de un gas mediante una nariz artificial y a una nariz artificial bioinspirada de aplicación general, que utiliza estrategias de modulación adaptativa de los parámetros del sensor dirigida por el objetivo dado a la nariz. La incorporación de dichas estrategias confiere a la nariz artificial de la invención unas reducidas dimensiones, por tanto, alta portabilidad, un amplio rango de aplicabilidad y un coste de producción reducido. The present invention relates to a method of analyzing a gas by means of an artificial nose and a bio-inspired artificial nose of general application, which uses adaptive modulation strategies of the sensor parameters directed by the objective given to the nose. The incorporation of said strategies gives the artificial nose of the invention reduced dimensions, therefore, high portability, a wide range of applicability and a reduced production cost.
ANTECEDENTES DE LA INVENCIÓN BACKGROUND OF THE INVENTION
Las narices electrónicas son máquinas diseñadas para efectuar la detección y discriminación de olores con precisión. Una definición generalmente aceptada de un sistema olfativo artificial fue dada por Gardner y Bartlett en 1994 (Oxford Press): "instrumento que comprende una agrupación de sensores químicos con sensibilidades parcialmente solapadas junto a un sistema de reconocimiento de patrones, capaz de analizar y reconocer aromas simples o complejos". Electronic noses are machines designed to accurately detect and discriminate odors. A generally accepted definition of an artificial olfactory system was given by Gardner and Bartlett in 1994 (Oxford Press): "instrument comprising a grouping of chemical sensors with partially overlapping sensitivities together with a pattern recognition system, capable of analyzing and recognizing aromas simple or complex. "
Los orígenes de la nariz electrónica se remontan a los años 60, cuando la compañía Bacharac Inc., construyó un primer dispositivo. En la década de los 80, surgen dos grupos de investigadores, en la Universidad de Warwick en Gran Bretaña y en el Argonne Nacional Laboratory (ANL) en Estados Unidos, debiéndose las primeras publicaciones a Krishna Persaud y George Dodd (1982). The origins of the electronic nose date back to the 1960s, when the Bacharac Inc. company built a first device. In the decade of the 80, two groups of researchers arise, at the University of Warwick in Great Britain and at the Argonne National Laboratory (ANL) in the United States, the first publications owing to Krishna Persaud and George Dodd (1982).
Desde entonces se han venido produciendo avances que han dado lugar a la fabricación comercial de narices electrónicas para su uso en distintos campos: agroindustria, contaminación ambiental, seguridad, medicina, etc. Since then there have been advances that have led to the commercial manufacture of electronic noses for use in different fields: agribusiness, environmental pollution, safety, medicine, etc.
En las narices electrónicas se distinguen generalmente tres módulos: de detección, electrónico y de procesamiento. En el módulo de detección se incluyen los sensores encargados de traducir de manera directa o indirecta la presencia de un olor en señales eléctricas. Cuando entran en contacto con componentes volátiles presentes en el gas, los sensores reaccionan, experimentando un cambio físico en sus propiedades. La respuesta del sensor se recibe en el módulo electrónico, que transforma la señal en un valor digital. Los valores se analizan a continuación en el módulo de procesamiento, que se encarga de realizar el reconocimiento y/o la clasificación de las señales registradas. In electronic noses, three modules are generally distinguished: detection, electronic and processing. The detection module includes the sensors responsible for directly or indirectly translating the presence of a smell into signals electric. When they come into contact with volatile components present in the gas, the sensors react, experiencing a physical change in their properties. The sensor response is received in the electronic module, which transforms the signal into a digital value. The values are analyzed below in the processing module, which is responsible for recognizing and / or classifying the recorded signals.
El método de funcionamiento de una nariz artificial comprende una etapa de aprendizaje o entrenamiento, en la que se somete a la nariz artificial al análisis de una serie de muestras reconocidas para construir modelos de referencia. En una etapa posterior de adquisición del olor, la nariz artificial es capaz de reconocer nuevas muestras a partir de los modelos de referencia. The method of operation of an artificial nose comprises a learning or training stage, in which the artificial nose is subjected to the analysis of a series of recognized samples to construct reference models. At a later stage of odor acquisition, the artificial nose is able to recognize new samples from the reference models.
Existen muchos tipos de sensores olfativos basados en diferentes principios físicos: quimiorresistivos, quimiocapacitivos, potenciométricos, gravimétricos, ópticos, acústicos, térmicos, poliméricos, amperimétricos, cromatográficos, espectrométricos, de efecto de campo, etc. There are many types of olfactory sensors based on different physical principles: chemoresistive, chemocapacitive, potentiometric, gravimetric, optical, acoustic, thermal, polymeric, ammeter, chromatographic, spectrometric, field effect, etc.
Los sensores quimiorresistivos son los más extendidos debido a su pequeño tamaño y su fácil integración en un circuito eléctrico. En el estado de la técnica se emplean matrices que combinan sensores de este tipo, que ofrecen ciertas características ventajosas al basar en ellos el diseño de una nariz electrónica comercial. Sin embargo, las matrices de sensores o componentes multisensor presentan también claras desventajas económicas, de fiabilidad, de estabilidad a lo largo del tiempo y de miniaturización. DESCRIPCIÓN DE LA INVENCIÓN Chemosensitive sensors are the most widespread due to their small size and easy integration into an electrical circuit. In the state of the art, matrices are used that combine sensors of this type, which offer certain advantageous characteristics, based on the design of a commercial electronic nose. However, sensor arrays or multisensor components also have clear economic disadvantages, reliability, stability over time and miniaturization. DESCRIPTION OF THE INVENTION
Las desventajas presentes en el estado de la técnica mencionadas anteriormente se superan mediante un método de análisis de un gas según la reivindicación 1 y una nariz artificial según la reivindicación 13. En las reivindicaciones dependientes se definen realizaciones preferidas de la presente invención. The disadvantages present in the prior art mentioned above are overcome by a gas analysis method according to claim 1 and an artificial nose according to claim 13. Preferred embodiments of the present invention are defined in the dependent claims.
En un primer aspecto inventivo se presenta un método de análisis de un gas mediante una nariz artificial que comprende al menos un sensor, comprendiendo el método: (a) detectar mediante al menos un sensor una muestra del gas a analizar, y In a first inventive aspect, a method of analyzing a gas by means of an artificial nose comprising at least one sensor is presented, the method comprising: (a) detecting by means of at least one sensor a sample of the gas to be analyzed, and
(b) modular adaptativamente al menos un parámetro que afecta al régimen de funcionamiento del sensor en función de una señal obtenida de la detección del sensor y de una medida de eficiencia definida en relación al objetivo dado a la nariz. (b) adaptively modulate at least one parameter that affects the rate of operation of the sensor based on a signal obtained from the detection of the sensor and a measure of efficiency defined in relation to the objective given to the nose.
En una realización preferida, la modulación adaptativa de al menos un parámetro se realiza mediante una función de retroalimentación que modifica al menos un parámetro que afecta al régimen de funcionamiento del sensor. In a preferred embodiment, the adaptive modulation of at least one parameter is performed by a feedback function that modifies at least one parameter that affects the operating mode of the sensor.
En una realización preferida, la medida de eficiencia se determina a partir de la comparación de la señal obtenida de la detección con al menos una segunda señal. La segunda señal puede ser una señal teórica o de referencia, o puede ser una segunda señal obtenida mediante una detección. In a preferred embodiment, the efficiency measure is determined from the comparison of the signal obtained from the detection with at least a second signal. The second signal may be a theoretical or reference signal, or it may be a second signal obtained by detection.
En una realización preferida, la medida de eficiencia se determina a partir de la comparación de la señal obtenida de la detección con al menos un valor umbral. In a preferred embodiment, the efficiency measure is determined from the comparison of the signal obtained from the detection with at least one threshold value.
La modulación de al menos un parámetro puede realizarse en función de medidas de eficiencia de reconocimiento de olores y/o discriminación de olores y/o clasificación de olores y/o en una etapa de aprendizaje. La modulación adaptativa de los parámetros puede ser discreta (respondiendo a eventos específicos detectados en la adquisición de la señal), o continua (durante todo el proceso de adquisición). La activación de la modulación se inicia automáticamente dependiendo déla tarea asignada a la nariz. Para el problema de reconocimiento de olores, la modulación de los parámetros se activa preferentemente cuando se determina que no se identifica un olor con los parámetros actuales del sensor. Para el problema de discriminación entre odorantes similares, la modulación de los parámetros se activa preferentemente cuando se determina que la señal de un odorante no proporciona suficientes características discriminantes con los parámetros actuales del sensor. Eventos típicos que definen la necesidad de iniciar una nueva modulación son la saturación de la señal o la llegada a un estado estacionario de la misma cuando todavía no se ha alcanzado el objetivo de la tarea asignada a la nariz. La temporalidad de estos eventos en general no se conoce a priori, y viene determinada por la comparación con la medida de eficiencia. La modulación adaptativa de al menos un parámetro puede realizarse durante una etapa de entrenamiento de la nariz artificial o durante la etapa de adquisición del olor por parte de la nariz artificial. The modulation of at least one parameter can be performed based on measures of efficiency of recognition of odors and / or discrimination of odors and / or classification of odors and / or in a learning stage. The adaptive modulation of the parameters can be discrete (responding to specific events detected in the acquisition of the signal), or continuous (during the entire acquisition process). The activation of the modulation starts automatically depending on the task assigned to the nose. For the problem of smell recognition, the modulation of the parameters is preferably activated when it is determined that a smell is not identified with the current sensor parameters. For the problem of discrimination between similar speakers, the modulation of the parameters is preferably activated when it is determined that the signal of an odorant does not provide sufficient discriminant characteristics with the current parameters of the sensor. Typical events that define the need to start a new modulation are the saturation of the signal or the arrival at a steady state of the same when the objective of the task assigned to the nose has not yet been achieved. The timing of these events in general is not known a priori, and is determined by the comparison with the efficiency measure. Adaptive modulation of at least one parameter can be performed during one stage of training the artificial nose or during the stage of acquisition of the smell by the artificial nose.
En una realización preferida, el parámetro a modular es el caudal de gas que incide sobre el sensor y/o la temperatura de calefacción. In a preferred embodiment, the parameter to be modulated is the gas flow rate that affects the sensor and / or the heating temperature.
Los parámetros a modular se seleccionan en función del tipo de sensor, que puede ser cualquier sensor olfativo. En el caso de usar un sensor quimiorresistivo, dos parámetros susceptibles de modularse adaptativamente son la temperatura de calefacción del sensor y el caudal de gas que incide sobre el sensor (sniffing). Para un sensor óptico puede modularse adaptativamente por ejemplo el caudal, la longitud de onda incidente en la superficie sensitiva y la longitud del camino óptico. En sensores quimiocapacitivos, el caudal y la amplitud (en tensión e intensidad) de la señal en frecuencia utilizada son susceptibles de modularse adaptativamente para determinar la capacidad eléctrica del sensor. En sensores gravimétricos QCM (quartz cristal micro balance) se puede variar el caudal y la frecuencia de resonancia base del conjunto modulando adaptativamente el módulo de Young con un pretensado piezoeléctrico. En sensores gravimétricos SAW (Surface acoustic wave) se puede modular adaptativamente el caudal y el tipo de pulso que se propaga (onda cuadrada, senoidal, rampa...). En sensores potenciométricos se puede modular adaptativamente el caudal y la presión de trabajo con objeto de variar de manera controlada la presión parcial del gas en la solución. The parameters to be modulated are selected according to the type of sensor, which can be any olfactory sensor. In the case of using a chemoresistant sensor, two parameters that can be adaptively modulated are the heating temperature of the sensor and the gas flow that affects the sensor (sniffing). For an optical sensor, the flow rate, the incident wavelength on the sensitive surface and the optical path length can be adaptively modulated. In chemocapacitive sensors, the flow rate and amplitude (in voltage and intensity) of the frequency signal used are susceptible to adaptively modulating to determine the electrical capacity of the sensor. In QCM gravimetric sensors (quartz crystal micro balance), the flow and base resonance frequency of the assembly can be varied by adaptively modulating Young's module with a piezoelectric prestressing. In SAW gravimetric sensors (Surface acoustic wave), the flow rate and the type of pulse that propagates (square, sine wave, ramp ...) can be adaptively modulated. Potentiometric sensors can adaptively modulate the flow and working pressure in order to vary in a controlled way the partial pressure of the gas in the solution.
En un segundo aspecto inventivo se presenta una nariz artificial que comprende: In a second inventive aspect an artificial nose is presented comprising:
- uno o varios sensores olfativos, y  - one or more olfactory sensors, and
- medios de procesamiento adaptados para modular adaptativamente al menos un parámetro que afecta al régimen de funcionamiento del sensor en función de una señal obtenida de la detección del sensor y de una medida de eficiencia referente al objetivo dado a la nariz. La nariz artificial según el segundo aspecto inventivo está adaptada para realizar el método según el primer aspecto inventivo y sus distintas realizaciones.  - processing means adapted to adaptively modulate at least one parameter that affects the operating mode of the sensor as a function of a signal obtained from the detection of the sensor and a measure of efficiency relative to the objective given to the nose. The artificial nose according to the second inventive aspect is adapted to perform the method according to the first inventive aspect and its different embodiments.
Ventajosamente, la nariz artificial de la invención puede estar basada en un único sensor, adaptado para trabajar en diferentes regímenes obtenidos a partir de la aplicación de estrategias consistentes en la modulación adaptativa de al menos un parámetro que afecta al funcionamiento y, por consiguiente, a la sensibilidad del sensor. Así, la nariz artificial de la invención tiene dimensiones y peso muy inferiores a los dispositivos olfativos considerados como portátiles en el mercado, por lo que puede considerarse ultraportátil. Advantageously, the artificial nose of the invention can be based on a single sensor, adapted to work in different regimes obtained from the application of strategies consisting of the adaptive modulation of at least one parameter that affects the operation and, consequently, the sensitivity of the sensor. Thus, the artificial nose of the invention has dimensions and weight much lower than the olfactory devices considered portable in the market, so it can be considered ultraportable.
En una realización preferida, el sensor consta de una única superficie sensitiva. In a preferred embodiment, the sensor consists of a single sensitive surface.
En una realización preferida, los medios de procesamiento comprenden un microcontrolador, un PC o un PLC (programmable logic controller). In a preferred embodiment, the processing means comprise a microcontroller, a PC or a PLC (programmable logic controller).
La introducción de estrategias de modulación adaptativa en la etapa de aprendizaje o entrenamiento y/o durante la adquisición del olor, tiene como resultado una nariz artificial más versátil que las del estado de la técnica, al ampliar el rango de sensibilidades respecto al de narices artificiales basadas en sensores no matriciales. De esta manera se permite su utilización en narices electrónicas de aplicación general obteniendo capacidades de detección y separación de aromas análogas e incluso superiores a las obtenidas en sistemas basados en una matriz de sensores de mayor coste y tamaño. La nariz artificial y el método de la invención presentan claras ventajas competitivas, relacionadas tanto con su bajo coste de producción como con su robustez, además de una sustancial simplificación de la electrónica encargada de realizar la amplificación, filtrado y acondicionamiento de la señal medida, con lo que se reduce sustancialmente el tamaño y el peso de la nariz artificial y se incrementa su portabilidad. The introduction of adaptive modulation strategies in the learning or training stage and / or during the acquisition of the smell, results in a more versatile artificial nose than the state of the art, by expanding the range of sensitivities with respect to artificial noses based on non-matrix sensors. In this way, its use is allowed in electronic noses of general application, obtaining capacities for detecting and separating aromas analogous and even higher than those obtained in systems based on a matrix of sensors of greater cost and size. The artificial nose and the method of the invention have clear competitive advantages, related both to its low production cost and its robustness, in addition to a substantial simplification of the electronics responsible for amplifying, filtering and conditioning the measured signal, with which substantially reduces the size and weight of the artificial nose and increases its portability.
En una realización preferida de la nariz artificial, el sensor es de tipo quimiorresistivo y la modulación adaptativa se lleva a cabo sobre el caudal de aire entrante y/o sobre la temperatura de calefacción, que es la temperatura a la que trabaja el sensor. Con la modulación adaptativa del caudal o flujo de aire (sniffíng), de manera análoga a como ocurre en la naturaleza, se enriquece la información procedente de las partículas olorosas que se encuentran en el gas sometido a análisis al introducir en él complejidad fluidodinámica que afecta a la presión, la temperatura, el recorrido libre medio de las partículas, la difusividad, etc. La modulación adaptativa del flujo de aire se puede realizar tanto durante la etapa de aprendizaje como durante la adquisición del olor. Con la modulación adaptativa de la temperatura de calefacción, de manera controlada y dependiente de la situación en que se encuentra el análisis, se regula el rango de valores de temperatura a los que se somete la superficie sensitiva del sensor. La variación de la temperatura de calefacción repercute en la concentración de odorantes sobre la superficie sensitiva, en su difusividad, etc. La modulación adaptativa de la temperatura de calefacción del sensor se puede realizar tanto durante la etapa de aprendizaje como durante la adquisición del olor. A pesar de que el presente método de análisis está previsto para realizarse preferentemente en una nariz artificial con un único sensor, es también de aplicación en narices artificiales con más de un sensor. In a preferred embodiment of the artificial nose, the sensor is chemo-resistive and the adaptive modulation is carried out on the incoming air flow and / or on the heating temperature, which is the temperature at which the sensor works. With the adaptive modulation of the flow or air flow (sniffing), in a manner analogous to what occurs in nature, information from the odorous particles found in the gas under analysis is enriched by introducing into it fluid dynamic complexity that affects at pressure, temperature, average free path of particles, diffusivity, etc. Adaptive air flow modulation can be performed both during the learning stage and during the acquisition of the smell. With the adaptive modulation of the heating temperature, in a controlled manner and dependent on the situation in which the analysis is found, the range of temperature values to which the sensor's sensitive surface is subjected is regulated. The variation of the heating temperature affects the concentration of odorants on the sensitive surface, its diffusivity, etc. Adaptive modulation of the heating temperature of the sensor can be performed both during the learning stage and during the acquisition of the smell. Although the present method of analysis is intended to be preferably performed on an artificial nose with a single sensor, it is also applicable in artificial noses with more than one sensor.
La invención permite el establecimiento teórico y operativo de las mejores funciones de modulación adaptativa en base al objetivo, que puede ser por ejemplo la detección de un olor, la discriminación entre dos o más olores, la clasificación de uno o varios olores en una serie de categorías, la identificación de un odorante en una mezcla, el mantenimiento de la estabilidad efectiva del sensor, etc. La medida de eficiencia determina los instantes y la manera de realizar la modulación adaptativa, que tiene lugar por eventos relevantes que se detectan en la señal en relación al objetivo dado a la nariz. La ocurrencia de estos eventos no se conoce a priori y, en general, no tienen por qué ser periódicos. Es importante diferenciar esta modulación adaptativa frente a una modulación construida a priori ya que en la modulación adaptativa se consigue el objetivo dado a la nariz de forma automatizada, mientras que en los otros casos hay que partir de un estudio previo específico del odorante, del hardware también específico de la nariz, y de una limitación intrínseca para establecer elementos de identificación y caracterización del odorante. The invention allows the theoretical and operational establishment of the best adaptive modulation functions based on the objective, which can be for example the detection of a smell, the discrimination between two or more odors, the classification of one or more odors in a series of categories, the identification of an odorant in a mixture, the maintenance of the effective stability of the sensor, etc. The efficiency measure determines the instants and the way of performing adaptive modulation, which takes place by relevant events that are detected in the signal in relation to the objective given to the nose. The occurrence of these events is not known a priori and, in general, they do not have to be periodic. It is important to differentiate this adaptive modulation from an a priori built modulation because in adaptive modulation the objective given to the nose is achieved in an automated way, while in the other cases it is necessary to start from a specific previous study of the odorant, of the hardware also specific to the nose, and an intrinsic limitation to establish elements of identification and characterization of the odorant.
Todas las características y/o las etapas de métodos descritas en esta memoria (incluyendo las reivindicaciones, descripción y dibujos) pueden combinarse en cualquier combinación, exceptuando las combinaciones de tales características mutuamente excluyentes. All features and / or the method steps described herein (including the claims, description and drawings) may be combined in any combination, except for combinations of such mutually exclusive features.
La presente invención es de aplicación en una serie de ámbitos, en los que se incluyen:The present invention is applicable in a number of areas, including:
• Industria: Control de calidad de productos, ayuda a la gestión de la producción, detección de caducidad, originalidad, etc. • Industry: Product quality control, production management assistance, expiration detection, originality, etc.
• Seguridad ciudadana, delincuencia y lucha antiterrorista: detección de drogas, explosivos, productos prohibidos y sustancias nocivas, cabinas o arcos de seguridad olfativos en aeropuertos y estaciones, sistemas anticopia de perfumes, colonias y consumibles en general, búsqueda de supervivientes en catástrofes, etc. Medio ambiente: Control de vertederos, aguas residuales, calidad ambiental, etc. Salubridad de entornos habitados: Calidad atmosférica en oficinas, aulas, centros públicos, etc. • Citizen security, crime and counterterrorism: detection of drugs, explosives, prohibited products and harmful substances, booths or arches of olfactory security at airports and stations, anti-copy systems of perfumes, colognes and consumables in general, search for survivors in disasters, etc. Environment: Control of landfills, wastewater, environmental quality, etc. Health of inhabited environments: Atmospheric quality in offices, classrooms, public centers, etc.
Ámbito sanitario: detección de infecciones, estudio de anósmias y predicción precoz de patologías neurodegenerativas asociadas, detección de cuadros oncológicos, análisis sanguíneos o de fluidos biogénicos, patologías del sistema endocrino, caracterización de tests olfativos clínicos, etc.  Health field: infection detection, study of anosmias and early prediction of associated neurodegenerative pathologies, detection of oncological conditions, blood or biogenic fluid analysis, pathologies of the endocrine system, characterization of clinical olfactory tests, etc.
Industria del ocio: museos de ciencias, aparatos tecnológicos, industria del juego, instalaciones recreativas.  Leisure industry: science museums, technological devices, gaming industry, recreational facilities.
Robótica (móvil e industrial).  Robotics (mobile and industrial).
DESCRIPCIÓN DE LOS DIBUJOS DESCRIPTION OF THE DRAWINGS
Para complementar la descripción que se está realizando y con objeto de ayudar a una mejor comprensión de las características de la invención, de acuerdo con un ejemplo preferente de realización práctica de la misma, se acompaña como parte integrante de dicha descripción un juego de figuras en donde con carácter ilustrativo y no limitativo, se ha representado lo siguiente: To complement the description that is being made and in order to help a better understanding of the characteristics of the invention, according to a preferred example of practical realization thereof, a set of figures in the accompanying part is accompanied as an integral part of said description. where for illustrative and non-limiting purposes, the following has been represented:
Figura 1.- Muestra una representación esquemática en alzado de una nariz artificial según la invención. Figura 2.- Muestra una representación esquemática en perspectiva del recorrido que efectúa un gas sometido a análisis en una nariz artificial según la invención. Figure 1.- Shows a schematic elevation of an artificial nose according to the invention. Figure 2.- Shows a schematic representation in perspective of the path made by a gas subjected to analysis in an artificial nose according to the invention.
Figura 3.- Muestra una representación esquemática de las señales y elementos de control de una nariz artificial según la invención. Figure 3.- Shows a schematic representation of the signals and control elements of an artificial nose according to the invention.
Figura 4.- Muestra una representación de (A)una matriz de seis sensores quimiorresistivos estándar y (B)una matriz virtual de sensores obtenida gracias a la variación de diferentes valores de temperatura de calefacción y caudal. Figura 5.- Muestra (A) una representación esquemática del flujo de información entre los módulos sensorial, electrónico y de procesamiento de una nariz artificial según el estado de la técnica y (B) según la presente invención. Figure 4.- It shows a representation of (A) an array of six standard chemoresistant sensors and (B) a virtual array of sensors obtained thanks to the variation of different heating and flow temperature values. Figure 5.- Shows (A) a schematic representation of the flow of information between the Sensory, electronic and processing modules of an artificial nose according to the state of the art and (B) according to the present invention.
Figura 6.- Muestra dos conjuntos de señales de dos olores diferentes realizadas por una matriz de cuatro superficies sensitivas. Figure 6.- It shows two sets of signals of two different odors made by a matrix of four sensitive surfaces.
Figura 7.- Muestra (A)dos lecturas obtenidas de dos olores diferentes realizadas en instantes distintos por una misma superficie sin modulación y (B) la lectura de estos dos mismos olores sometidos a diferentes regímenes de modulación en los instantes t2, t3 y t4. Estos instantes están definidos por la medida de eficiencia y en general no se pueden predeterminar. Figure 7.- Sample (A) two readings obtained from two different odors made in different instants by the same surface without modulation and (B) the reading of these two same odors subjected to different modulation regimes at times t 2 , t 3 and t 4 . These moments are defined by the efficiency measure and in general cannot be predetermined.
Figura 8. -Muestra un ejemplo de modulación adaptativa según la invención para la tarea de discriminar dos concentraciones muy similares de etanol. Figure 8. - Shows an example of adaptive modulation according to the invention for the task of discriminating two very similar concentrations of ethanol.
REALIZACIÓN PREFERENTE DE LA INVENCIÓN PREFERRED EMBODIMENT OF THE INVENTION
A la vista de las figuras se describe a continuación un modo de realización preferente de la nariz artificial objeto de esta invención. In view of the figures, a preferred embodiment of the artificial nose object of this invention is described below.
En las figuras 1 y 2 se muestra esquemáticamente una nariz artificial ultraportátil según una realización de la invención. La nariz artificial comprende un sensor (10), una placa electrónica (3) y un microcontrolador (12) alojados en el interior de una envolvente (2). La envolvente presenta una serie de accesos mediante los cuales se permite la entrada y/o salida del gas a analizar en la nariz artificial. An ultraportable artificial nose according to an embodiment of the invention is schematically shown in Figures 1 and 2. The artificial nose comprises a sensor (10), an electronic board (3) and a microcontroller (12) housed inside an envelope (2). The envelope has a series of accesses through which the entry and / or exit of the gas to be analyzed in the artificial nose is allowed.
Durante el funcionamiento de la nariz artificial se hace penetrar (7) el gas en la nariz artificial a través de un primer acceso (4). En este caso se fuerza la entrada de gas mediante un ventilador (9), de manera que el gas incide directamente en el sensor (10). El sensor (10) seleccionado para ilustrar la invención es de tipo quimiorresistivo y cuenta con cuatro pines, dos para la alimentación de la temperatura de calefacción y otros dos para su salida de señal. During operation of the artificial nose, the gas is penetrated (7) into the artificial nose through a first access (4). In this case, the gas inlet is forced through a fan (9), so that the gas directly affects the sensor (10). The sensor (10) selected to illustrate the invention is of the chemoresistant type and has four pins, two for the supply of the heating temperature and another two for its signal output.
En este ejemplo de realización, el ventilador responsable del bombeo de gas es un ventilador axial de reducidas dimensiones capaz de generar un flujo de hasta 2.7m3/h. Preferentemente, el ventilador (9)se encuentra fijado a una pared interior de la envolvente (2), de modo que fuerza la entrada de gas directamente sobre el sensor. In this exemplary embodiment, the fan responsible for pumping gas is an axial fan of small dimensions capable of generating a flow of up to 2.7m 3 / h. Preferably, the fan (9) is fixed to an inner wall of the enclosure (2), so that it forces the gas inlet directly on the sensor.
La nariz artificial del ejemplo presenta un segundo acceso (5), realizado como un conjunto de orificios (5), para la salida (8) del gas al exterior de la nariz. Pueden proporcionarse accesos adicionales, por ejemplo un tercer acceso (6) para la salida de un cable multihilo (11) responsable de portar las comunicaciones y alimentar eléctricamente la nariz artificial. The artificial nose of the example has a second access (5), made as a set of holes (5), for the exit (8) of the gas to the outside of the nose. Additional accesses can be provided, for example a third access (6) for the output of a multi-wire cable (11) responsible for carrying the communications and electrically feeding the artificial nose.
La electrónica se ha ubicado en el interior de una envolvente (2) de ABS comercial de 50 x 35 x 17mm sobre cuyo lateral se ha facilitado con un taladro el paso del cable de alimentación y comunicaciones. En la tapa (1) de la envolvente (2) se han mecanizado dos conjuntos de orificios para el acceso y salida del gas a analizar. El tamaño de los orificios de entrada de gas (4) es preferentemente de aproximadamente 0.4mm. El tamaño de los orificios de salida de gas (5) es preferentemente de aproximadamente I mm.EI tamaño del taladro para el cable de comunicaciones (6) es preferentemente de aproximadamente 5mm de diámetro. The electronics have been placed inside a 50 x 35 x 17mm commercial ABS envelope (2) on whose side the passage of the power and communications cable has been facilitated with a hole. In the cover (1) of the envelope (2) two sets of holes have been machined for the access and exit of the gas to be analyzed. The size of the gas inlet holes (4) is preferably about 0.4mm. The size of the gas outlet orifices (5) is preferably about I mm. The size of the hole for the communication cable (6) is preferably about 5mm in diameter.
Para la implementación de la nariz artificial según esta realización preferida, se dispone de un dispositivo electrónico microcontrolado capaz de regular tanto la temperatura de calefacción como el caudal de gas. La modulación adaptativa de la temperatura de calefacción y el caudal se realiza en esta realización por medio de sendos sistemas de control de potencia en puerta FET de tipo PWM con filtro paso bajo. For the implementation of the artificial nose according to this preferred embodiment, there is a microcontrolled electronic device capable of regulating both the heating temperature and the gas flow. The adaptive modulation of the heating temperature and the flow rate is carried out in this embodiment by means of two PWM type FET gate power control systems with low pass filter.
Para facilitar su eventual conexión con unos medios de procesamiento externos (17), tales como un ordenador o un PLC (Programmable logic control^ el dispositivo tiene dos modos de comunicación: un módulo de comunicación por protocolo USB y un módulo RS- 485 para sistemas multipunto de larga distancia. Los medios de procesamiento han de estar adaptados para la adquisición de las lecturas de señales y su análisis. Así, la modulación adaptativa del caudal de gas y de la temperatura de calefacción del sensor puede ser controlada por el microcontrolador empotrado en la nariz artificial o por un PC o PLC externos. La posibilidad de modular adaptativamente, en función de eventos definidos por el objetivo dado a la nariz, tanto el caudal de gas como la temperatura se integra como una funcionalidad adicional en el algoritmo de aprendizaje y/o clasificación, aumentando la capacidad de discriminación del equipo. Durante el proceso de análisis ambos parámetros pueden ajustarse dinámicamente y en tiempo real en base al estado de adquisición en el que se encuentra la nariz artificial. To facilitate its eventual connection with external processing means (17), such as a computer or a PLC (Programmable logic control ^ the device has two communication modes: a USB protocol communication module and an RS-485 module for systems Long distance multipoint The processing means must be adapted for the acquisition of the signal readings and their analysis Thus, the adaptive modulation of the gas flow and the heating temperature of the sensor can be controlled by the microcontroller embedded in the artificial nose or by an external PC or PLC The possibility of adaptively modulating, depending on events defined by the objective given to the nose, both the gas flow and the temperature is integrated as an additional functionality in the learning algorithm and / or classification, increasing the discrimination capacity of the equipment During the analysis process both parameters can be adjusted din ically and in real time based on the state procurement in the that is the artificial nose.
En la realización ejemplificada en la figura 3, el microcontrolador (12) alojado en la placa electrónica (3) modula adaptativamente la actividad respectiva de los sistemas de control de potencia de la temperatura de calefacción (13) del sensor quimiorresistivo (10) y del caudal (14) del ventilador (9) por medio de dos señales (18) reguladas por ancho de pulso (método clásico de regulación y gestión de energía conocido típicamente como PWM). Además cuenta con sendos módulos de comunicación (15, 16) dedicados a la transferencia de información a los medios de procesamiento externos (17). In the embodiment exemplified in FIG. 3, the microcontroller (12) housed in the electronic board (3) adaptively modulates the respective activity of the heating temperature power control systems (13) of the chemoresistant sensor (10) and of the flow rate (14) of the fan (9) by means of two signals (18) regulated by pulse width (classical method of regulation and energy management typically known as PWM). It also has two communication modules (15, 16) dedicated to the transfer of information to external processing means (17).
En la figura 4 se muestra a modo de comparación una matriz de seis sensores (a-f) quimiorresistivos reales de una nariz artificial del estado de la técnica (A) y la matriz de sensores virtuales (representados en color más claro) con diferentes sensibilidades de una nariz artificial según la invención (B), obtenidos a partir de un único sensor (sensor de funciones de modulación adaptativas T1 de temperatura, F1 de flujo representado más oscuro), sometido a diferentes funciones de modulación adaptativa (Tx) de las temperaturas de calefacción y a diferentes funciones de modulación adaptativa (Fy) de valores de caudal o flujo de gas con odorante que se hace pasar por su superficie. Gracias a la modulación adaptativa de parámetros, la nariz artificial de la invención es capaz de obtener sensibilidades efectivas diferentes y parcialmente solapadas a partir de una única superficie sensitiva, de manera equivalente a las sensibilidades que se obtendrían utilizando un elevado número de sensores virtuales funcionando de manera consecutiva. Al ir modulando su régimen de funcionamiento adaptativamente con diferentes caudales y temperaturas de calefacción, se obtienen con un único sensor resultados análogos e incluso superiores a los que se obtendrían al usar de una en una las diferentes superficies sensitivas de una matriz de múltiples sensores, debido al aumento de la especificidad de la señal registrada. En una realización preferida, la modulación adaptativa se realiza mediante una función de retroalimentación m(f) que modifica los parámetros de la adquisición (y/o del aprendizaje y/o del reconocimiento) en base a una función de eficiencia del objetivo dado a la nariz (por ejemplo una función que mide la distancia entre señales). Por ejemplo, la modulación adaptativa por temperatura para discriminar dos señales Sa 1 y Sa 2 con un único sensor a puede expresarse como mT( =f[d(SaV,T(t)),Sa 2(f,T(t))], donde d es la función de distancia que compara las señales S1 y S2en un tiempo t y T es el valor de la temperatura del sensor en ese instante. Análogamente, la modulación adaptativa por flujo puede expresarse como: mF( =f[d(SaV,F(t)),Sa 2(f,F(t))], donde F es el flujo de aire del sensor en el instante t. Una modulación adaptativa por flujo y temperatura puede expresarse como mTF( =f[tf(SaV ( >F(t)),Sa 2( T(t),F(t))]. En general, una modulación adaptativa de p parámetros representados por el vector α para discriminar n señales puede expresarse como: ma(f)=f[d(Sa 1(f,a(t)),Sa 2(f,a(t)), ... ,Sa n(f,a(t))].Los tiempos t donde se hace efectiva la modulación se determinan por eventos observados en la señal del sensor y se definen automáticamente en relación al objetivo dado a la nariz. Figure 4 shows by comparison a matrix of six real chemo-resistive sensors (af) of a state-of-the-art artificial nose (A) and the virtual sensor matrix (represented in lighter color) with different sensitivities of a artificial nose according to the invention (B), obtained from a single sensor (adaptive temperature modulation function sensor T1, flow darker represented F1), subjected to different adaptive modulation functions (Tx) of heating temperatures and to different functions of adaptive modulation (Fy) of flow or gas flow values with odorant that is passed through its surface. Thanks to the adaptive modulation of parameters, the artificial nose of the invention is able to obtain different and partially overlapped effective sensitivities from a single sensitive surface, equivalent to the sensitivities that would be obtained using a high number of virtual sensors operating from consecutive way. By modulating its operating regime adaptively with different flow rates and heating temperatures, similar and even higher results are obtained with a single sensor than would be obtained by using one by one the different sensitive surfaces of a matrix of multiple sensors, due to to the increase in the specificity of the registered signal. In a preferred embodiment, adaptive modulation is performed by means of a feedback function m (f) that modifies the parameters of acquisition (and / or learning and / or recognition) based on an objective efficiency function given to the nose (for example a function that measures the distance between signals). For example, adaptive temperature modulation to discriminate between two signals S at 1 and S at 2 with a single sensor a can be expressed as m T (= f [d (S to V, T (t)), S to 2 (f , T (t))], where d is the distance function that compares the signals S 1 and S 2 at a time t and T is the value of the sensor temperature at that moment. Similarly, adaptive flow modulation can be expressed as: m F (= f [d (S to V, F (t)), S to 2 (f, F (t))], where F is the air flow of the sensor at time t An adaptive modulation by flow and temperature can be expressed as m T F ( = f [tf (S to V ( > F (t)), S to 2 (T (t), F (t)) In general, an adaptive modulation of p parameters represented by the α vector to discriminate n signals can be expressed as: m a (f) = f [d (S to 1 (f, a (t)), S to 2 ( f, a (t)), ..., S a n (f, a (t))] The times t where modulation is effective are determined by events observed in the sensor signal and are automatically defined in relation to to the objective given to the nose.
El módulo encargado de gestionar la modulación adaptativa del o de los parámetros es el módulo de procesamiento, que es capaz de variar estos parámetros en tiempo real de manera adaptativa para optimizar la detección y discriminación del olor en función del objetivo dado a la nariz. The module responsible for managing the adaptive modulation of the parameter (s) is the processing module, which is able to vary these parameters in real time in an adaptive manner to optimize the detection and discrimination of the odor depending on the objective given to the nose.
Esta práctica discretiza en el tiempo la posibilidad de lectura de cada sensor virtual y resulta equivalente a multiplicaren el ámbito analógico el número de sensores posibles. Es decir, en una matriz de sensores clásica como la representada en la figura 4A, las señales procedentes de todos y cada uno de los sensores reales que la componen es accesible en el mismo instante de tiempo. Con la nariz artificial y el método según la invención, en cada instante de tiempo sólo puede realizarse la lectura de un único sensor. Sin embargo, el tamaño de la matriz de sensores virtuales accesible durante un periodo de tiempo se incrementa en varios órdenes de magnitud y su forma puede adecuarse a la dinámica de cada lectura. This practice discretizes over time the possibility of reading each virtual sensor and is equivalent to multiplying the number of possible sensors in the analog field. That is, in a classic sensor array such as that shown in Figure 4A, the signals from each and every one of the actual sensors that compose it are accessible at the same time. With the artificial nose and the method according to the invention, only one single sensor can be read at any time. However, the size of the virtual sensor array accessible over a period of time is increased by several orders of magnitude and its shape can be adapted to the dynamics of each reading.
En la figura 5A se representan los módulos sensorial (21), electrónico (22) y de procesamiento(23) junto con el flujo de información que se produce entre ellos en una nariz artificial tradicional. Análogamente, en la figura 5B se representan respectivamente los módulos sensorial (24), electrónico (25) y de procesamiento (26) junto con el flujo de información y la modulación que se produce entre ellos en la nariz artificial según la presente invención. Figure 5A shows the sensory (21), electronic (22) and processing (23) modules together with the flow of information that occurs between them in a traditional artificial nose. Similarly, in Figure 5B, the sensory (24), electronic (25) and processing (26) modules are represented respectively together with the information flow and the modulation that occurs between them in the artificial nose according to the present invention.
La figura 6 es un ejemplo del método clásico para la discriminación de olores. En ella se muestran en función del tiempo (t) dos conjuntos de señales (Sa 1 , Sb 1 , Sc 1 , Sd 1 ; Sa 2, Sb 2, Sc2, Sd 2) para dos olores diferentes (1 y 2) realizadas por una matriz de cuatro superficies sensitivas (a,b,c,d). En la figura se observa que aunque las señales (SC 1 ,SC 2) obtenidas por una misma superficie son difícilmente distinguibles para los dos olores, las otras señales (Sa 1 , Sb 1 , Sd 1 ;Sa 2, Sb 2, Sd 2) son claramente diferentes para los dos olores, es decir, tres de las cuatro superficies sensitivas aportan información adicional del olor con la que es posible realizar la discriminación. Figure 6 is an example of the classic method for odor discrimination. It shows, as a function of time (t), two sets of signals (S a 1 , S b 1 , S c 1 , S d 1 ; S a 2 , S b 2 , Sc 2 , S d 2 ) for two different odors (1 and 2) made by a matrix of four sensitive surfaces (a, b, c, d). The figure shows that although the signals (S C 1 , S C 2 ) obtained by the same surface are hardly distinguishable for the two odors, the other signals (S a 1 , S b 1 , S d 1 ; S a 2 , S b 2 , S d 2 ) are clearly different for the two odors, that is, three of the four sensitive surfaces provide additional information on the smell with which discrimination is possible.
En la figura 7 A se muestra una gráfica que representa dos lecturas de señales (Sa 1 ; Sa 2) obtenidas para dos olores diferentes en función del tiempo, realizadas en instantes distintos por una misma superficie sensitiva a manteniendo los parámetros de modulación constantes. Como se observa, puede darse el caso de que los dos olores produzcan señales difícilmente distinguibles en un determinado régimen de funcionamiento del sensor. En la figura 7B se representa el efecto producido en la lectura de señales para estos dos mismos olores, que en un primer instante (ti) son indistinguibles pero que sometidos a diferentes regímenes en los instantes (t2, t3, t4) en los que se ha modificado adaptativamente un parámetro de modulación, son fácilmente distinguibles. En el caso de sensores quimiorresistivos estos parámetros pueden ser la temperatura de calefacción y/o el caudal. En la Figura 8 se muestra un ejemplo de modulación de flujo de gas para discriminar dos concentraciones muy parecidas de etanol. Sin modulación la nariz no es capaz de discriminar estas dos concentraciones. En este ejemplo Sa 1 corresponde a la señal registrada por la nariz artificial de la invención para etanol al 0.5% y Sa 2 corresponde a la señal registrada para etanol al 0.45%. La modulación mF (en este ejemplo, de flujo de gas F) se realiza hasta que la distancia d entre las dos señales alcanza un umbral adecuado. Los instantes en los que se realiza una modulación de flujo se indican con flechas. El panel de la izquierda muestra las señales obtenidas en función del tiempo y el panel de la derecha muestra la distancia instantánea (d) entre las señales, junto con el umbral considerado adecuado para la discriminación (0.04V en este ejemplo). Esto es, en este ejemplo la medida de eficiencia del proceso sería la distancia entre las dos señales registradas, realizada como la diferencia entre una y otra. En otras realizaciones la distancia entre señales puede calcularse de otra forma, de manera que no sea necesariamente la diferencia entre una y otra. Mientras la distancia es menor que el valor umbral establecido, se realiza la modulación adaptativa del flujo de gas incidente sobre el sensor. Figure 7 A shows a graph representing two signal readings (S to 1 ; S to 2 ) obtained for two different odors as a function of time, made at different times by the same sensitive surface to keep the modulation parameters constant . As can be seen, it may be the case that the two odors produce signals that are difficult to distinguish in a certain operating mode of the sensor. Figure 7B shows the effect produced in the reading of signals for these two same odors, which at first (ti) are indistinguishable but subject to different regimes at instants (t 2 , t 3 , t 4 ) in those that a modulation parameter has been adaptively modified are easily distinguishable. In the case of chemoresistant sensors these parameters may be the heating temperature and / or the flow rate. An example of gas flow modulation to discriminate two very similar concentrations of ethanol is shown in Figure 8. Without modulation the nose is not able to discriminate these two concentrations. In this example S to 1 corresponds to the signal recorded by the artificial nose of the invention for 0.5% ethanol and S to 2 corresponds to the signal recorded for 0.45% ethanol. Modulation m F (in this example, gas flow F) is performed until the distance d between the two signals reaches an appropriate threshold. The moments in which a flow modulation is performed are indicated by arrows. The panel on the left shows the signals obtained as a function of time and the panel on the right shows the instantaneous distance (d) between the signals, together with the threshold considered appropriate for discrimination (0.04V in this example). That is, in this example the measure of process efficiency would be the distance between the two recorded signals, made as the difference between one and the other. In other embodiments the distance between signals can be calculated in another way, so that it is not necessarily the difference between one and the other. While the distance is less than the set threshold value, modulation is performed adaptive of the gas flow incident on the sensor.
El panel inferior muestra la función de modulación (mF) utilizada en este ejemplo, que corresponde a una función que modifica el flujo de gas en la dirección adecuada si no se ha alcanzado el umbral de discriminación en un intervalo de tiempo. Una vez que la distancia entre ambas señales ha alcanzado el umbral establecido, se considera que la discriminación entre las dos señales es satisfactoria y el proceso termina. En general pueden emplearse funciones más complejas en las que la modificación del parámetro a modular sea dependiente de la medida de eficiencia empleada definida en relación al objetivo dado a la nariz. The lower panel shows the modulation function (m F ) used in this example, which corresponds to a function that modifies the gas flow in the appropriate direction if the discrimination threshold has not been reached in a time interval. Once the distance between the two signals has reached the established threshold, the discrimination between the two signals is considered satisfactory and the process ends. In general, more complex functions can be used in which the modification of the parameter to be modulated is dependent on the measure of efficiency employed defined in relation to the objective given to the nose.
En el ejemplo ilustrado mediante la Figura 8 la modulación adaptativa de los parámetros es discreta, pero en otros casos podría ser continua. A pesar de que en varios ejemplos se han mencionado el caudal de gas y la temperatura de calefacción como parámetros modulables en relación con un sensor quimiorresistivo, se entenderá que las explicaciones anteriores son igualmente aplicables a otros parámetros modulables en relación con otros tipos de sensores olfativos. In the example illustrated by Figure 8 the adaptive modulation of the parameters is discrete, but in other cases it could be continuous. Although in several examples the gas flow rate and the heating temperature have been mentioned as modulable parameters in relation to a chemoresistant sensor, it will be understood that the above explanations are equally applicable to other modulable parameters in relation to other types of olfactory sensors .

Claims

REIVINDICACIONES
1. Método de análisis de un gas caracterizado porque se realiza mediante una nariz artificial que comprende al menos un sensor, y porque comprende las siguientes etapas: detectar mediante al menos un sensor una muestra del gas a analizar, y modular adaptativamente al menos un parámetro que afecta al régimen de funcionamiento del sensor en función de una señal obtenida de la detección del sensor y de una medida de eficiencia referente al objetivo dado a la nariz; esta medida de eficiencia determina los instantes y la manera de realizar la modulación adaptativa, que tiene lugar por eventos relevantes que se detectan en la señal en relación al objetivo dado a la nariz. 1. Method of analysis of a gas characterized in that it is carried out by means of an artificial nose comprising at least one sensor, and because it comprises the following steps: detecting by means of at least one sensor a sample of the gas to be analyzed, and adaptively modulating at least one parameter which affects the operating regime of the sensor as a function of a signal obtained from the detection of the sensor and a measure of efficiency concerning the objective given to the nose; This measure of efficiency determines the instants and the way of performing adaptive modulation, which takes place by relevant events that are detected in the signal in relation to the objective given to the nose.
2. Método de análisis de un gas según la reivindicación 1 , caracterizado porque la modulación del al menos un parámetro se realiza mediante una función de retroalimentación que modifica al menos un parámetro en función de la medida de eficiencia. 2. Method of analyzing a gas according to claim 1, characterized in that the modulation of the at least one parameter is carried out by means of a feedback function that modifies at least one parameter depending on the efficiency measure.
3. Método de análisis de un gas según la reivindicación 1 ó 2, caracterizado porque la medida de eficiencia se determina a partir de la comparación de la señal obtenida de la detección con al menos una segunda señal. 3. Method of analysis of a gas according to claim 1 or 2, characterized in that the efficiency measurement is determined from the comparison of the signal obtained from the detection with at least a second signal.
4. Método de análisis de un gas según la reivindicación 3, caracterizado porque la segunda señal es una señal de referencia. 4. Method of analysis of a gas according to claim 3, characterized in that the second signal is a reference signal.
5. Método de análisis de un gas según la reivindicación 3, caracterizado porque la segunda señal es una segunda señal obtenida de una detección. 5. Method of analyzing a gas according to claim 3, characterized in that the second signal is a second signal obtained from a detection.
6. Método de análisis de un gas según la reivindicación 1 ó 2, caracterizado porque la medida de eficiencia se determina a partir de la comparación de la señal obtenida de la detección con al menos un valor umbral. 6. Method of analysis of a gas according to claim 1 or 2, characterized in that the efficiency measurement is determined from the comparison of the signal obtained from the detection with at least one threshold value.
7. Método de análisis de un gas según una cualquiera de las reivindicaciones anteriores, caracterizado porque la modulación de al menos un parámetro se realiza en función de medidas de eficiencia de reconocimiento y/o discriminación y/o clasificación y/o aprendizaje de la señal obtenida de la detección. 7. Method of analyzing a gas according to any one of the preceding claims, characterized in that the modulation of at least one parameter is carried out based on efficiency measures of recognition and / or discrimination and / or classification and / or signal learning Obtained from detection.
8. Método de análisis de un gas según una cualquiera de las reivindicaciones anteriores, caracterizado porque la modulación adaptativa de al menos un parámetro es discreta. 8. Method of analysis of a gas according to any one of the preceding claims, characterized in that the adaptive modulation of at least one parameter is discrete.
9. Método de análisis de un gas según una cualquiera de las reivindicaciones 1 -7, caracterizado porque la modulación adaptativa de al menos un parámetro es continua. 9. Method of analysis of a gas according to any one of claims 1-7, characterized in that the adaptive modulation of at least one parameter is continuous.
10. Método de análisis de un gas según una cualquiera de las reivindicaciones anteriores, caracterizado porque la modulación de al menos un parámetro se realiza durante una etapa de entrenamiento de la nariz artificial. 10. Method of analysis of a gas according to any one of the preceding claims, characterized in that the modulation of at least one parameter is carried out during a training stage of the artificial nose.
1 1. Método de análisis de un gas según una cualquiera de las reivindicaciones anteriores, caracterizado porque la modulación de al menos un parámetro se realiza durante una etapa de adquisición de la nariz artificial. 1 1. Method of analyzing a gas according to any one of the preceding claims, characterized in that the modulation of at least one parameter is carried out during an acquisition stage of the artificial nose.
12. Método de análisis de un gas según una cualquiera de las reivindicaciones anteriores, caracterizado porque el parámetro a modular es el caudal de aire que incide sobre el sensor y/o la temperatura de calefacción. 12. Method of analyzing a gas according to any one of the preceding claims, characterized in that the parameter to be modulated is the flow of air that affects the sensor and / or the heating temperature.
13. Nariz artificial caracterizada porque comprende: 13. Artificial nose characterized by comprising:
- al menos un sensor (10) de olor y  - at least one odor sensor (10) and
-medios de procesamiento (12) adaptados para modular adaptativamente al menos un parámetro que afecta al régimen de funcionamiento del sensor (10) en función de una señal obtenida de la detección del sensor y de una medida de eficiencia.  -processing means (12) adapted to adaptively modulate at least one parameter that affects the operating regime of the sensor (10) as a function of a signal obtained from the detection of the sensor and a measure of efficiency.
14. Nariz artificial según reivindicación 13 caracterizada porque el sensor (10) es un sensor de una única superficie sensitiva. 14. Artificial nose according to claim 13 characterized in that the sensor (10) is a sensor with a single sensitive surface.
15. Nariz artificial según la reivindicación 13 ó 14 caracterizada porque el sensor (10) es un sensor quimiorresistivo. 15. Artificial nose according to claim 13 or 14, characterized in that the sensor (10) is a chemoresistant sensor.
16. Nariz artificial según una de las reivindicaciones 13-15 caracterizada porque los medios de procesamiento (12) están adaptados para modular el caudal de aire que incide sobre el sensor y/o la temperatura de calefacción. 16. Artificial nose according to one of claims 13-15, characterized in that the processing means (12) are adapted to modulate the air flow that affects the sensor and / or the heating temperature.
17. Nariz artificial según una de las reivindicaciones 13-16 caracterizada porque los medios de procesamiento comprenden un microcontrolador, un PC o un PLC. 17. Artificial nose according to one of claims 13-16, characterized in that the processing means comprise a microcontroller, a PC or a PLC.
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