CN100399015C - Apparatus and method for detecting gas using single sensor - Google Patents

Abstract

Method and device use simple transducer identifying and detecting variety gases, utilizing different kinds of gaseous molecule having different chemical property and different output quantity variation mode as acting with transducer, to realize variety gaseous detecting. Said invented device includes at least one transducer probe, microprocessor and output equipment; wherein transducer probe set with heating module and transducer sensitive film, heating module and transducer sensitive film respectively connected with computer or other data acquisition facility, through above-mentioned device and microprocessor controlling transducer probe temperature and simultaneously collecting and processing transducer probe output voltage.

Description

A kind of method and apparatus with the single-sensor detected gas

Technical field

The present invention relates to a kind of dynamic response signal that utilizes single-sensor and discern and detect the molecular method of multiple organic or inorganic, the identification and the concentration that specially refer to organic volatile, inflammable gas and environmental pollution gas such as CO, oxides of nitrogen etc. detect.

The invention still further relates to a kind of Electronic Nose device of realizing said method.

Background technology

Electronic Nose (be operated in also crying in the liquid medium electronic tongue) is a kind of environment supervision instrument, and it can a lot of organic and inorganic molecules of detection and Identification.At present Electronic Nose generally is defined as and a kind ofly is made up of a sensor array with different sensitivity characteristics and pattern recognition system, is used for discerning and detect the instrument of various organic and inorganic molecules.Present Electronic Nose is carried out pattern-recognition to the identification of sensitive molecule output valve by to the sensor array column balancing time and is realized, utilizes the dynamic corresponding signal of single-sensor to realize that detected material identification yet there are no report.

Summary of the invention

The object of the present invention is to provide a kind of dynamic response signal that utilizes single-sensor to discern and detect the molecular method of multiple organic or inorganic.

Another purpose of the present invention is to provide a kind of Electronic Nose (tongue) that is used to realize said method.

Identification provided by the invention and detection method and Electronic Nose (tongue), can use simple recognizer to replace algorithm for pattern recognition, reduced number of sensors simultaneously, hardware complexity and computation complexity have been reduced, thereby reduction hardware cost, also have very high discrimination, help large-scale commercial applicationsization.

For achieving the above object, the method of multiple organic or inorganic molecule is discerned and detected to the dynamic response signal that utilizes single-sensor provided by the invention, the principle of its foundation is, because the chemical property difference of various detected molecules, difference appears in the effect of molecule and sensor sensing material, though the output quantity of sensor (is led as electricity during balance, temperature, quality, pressure, change in color or the like) may be identical, but they reach the chemical process that takes place in the process of balance and certainly exist difference, show sensor output quantity changing pattern difference in the mechanism.The present invention realizes the identification and the detection of detected molecule just according to the difference of these patterns.

Specifically, the present invention is controlled at the sensor probe temperature in some scopes by computing machine and makes this temperature range be cyclical variation, the character of this temperature range view sensor sensitive material and detected molecule and deciding.Certain reaction takes place in various tested molecules under different temperature, this moment, the tested molecule of variable concentrations and different components can demonstrate a series of response signals by sensor probe, note the response signal of this sensor probe and the curve that meets with a response with computing machine, to the calculating of differentiating of this serial curve, and can discern and detect the composition and the concentration of each molecule after relatively with the typical curve that pre-establishes.

By sequence of operation, step of the present invention is:

A) temperature programmed control is accurately controlled temperature variation in one-period;

B) output voltage of at least one sensor of real time record;

D) discern the output voltage curve of this sensor, to the calculating of differentiating of this serial curve;

E) typical curve with this gas calculates its concentration.

Described method, multiple gases wherein are multiple organic or inorganic molecule.

Described method, wherein range of temperature comprises the sensitive temperature interval of detected gas among the step a.

Described method, wherein the serial curve in the steps d is the voltage curve of multiple gases through same sensor output.

The device that is used to realize above-mentioned method provided by the invention, it mainly is made up of at least one sensor probe, microprocessor and recording unit; Wherein:

Sensor probe is provided with heating module and sensor sensing film;

Heating module is connected with computing machine respectively with sensor sensing film;

By said apparatus, microprocessor control sensor probe temperature, the output voltage of collection and processes sensor probe simultaneously.

Described device, wherein heating module is connected with computing machine by the D/A interface, and sensor sensing film is connected with computing machine by the A/D interface.

Described device wherein is pasted with thermistor on the sensor sensing film, and this thermistor is connected with computing machine by the A/D interface.

Described device, display device wherein are graphoscope, charactron, Liquid Crystal Module, loudspeaker or other output unit.

The present invention adopts the computer control temperature, and is known technology with technology such as computer recording and data processing, and those skilled in the art are readily appreciated that and implement.

Description of drawings

Fig. 1 proving installation synoptic diagram of the present invention.Wherein Fig. 1 a is the sensor probe structure, and Fig. 1 b is the structural drawing of whole test system;

Fig. 2 is the probe temperature curve.7 curves among the figure are respectively to inject the methyl alcohol total amount to be respectively 0.1uL, 0.2uL, and 0.5uL, 1.0uL, 2.0uL, sensor probe variation of temperature curve in 7 different measurings of 5.0uL and 10.0uL, they overlap basically;

Fig. 3 is the output voltage curve of sensor to ethanol;

Fig. 4 is the output voltage curve of sensor to methyl alcohol;

Fig. 5 is that the differential signal of methyl alcohol, ethanol sensor output voltage curve compares;

Fig. 6 is that methyl alcohol, ethanol, benzene and four kinds of gases of water vapor compare through the differential signal of same sensor output voltage curve;

Fig. 7 is the typical curve of sensor output methyl alcohol, and wherein horizontal ordinate is proportional to the logarithm of its concentration, and ordinate is proportional to the logarithm of sensor sensing film resistance value.

Embodiment

Below in conjunction with accompanying drawing, describe the present invention in detail with specific embodiment and utilize the dynamic response signal of single-sensor to discern and detect the method for various organic or inorganic molecules.

According to the present invention, realize the single-sensor Electronic Nose, at first require selecting a kind ofly all has the sensor of response to tested gas, and determines that the sensitive temperature of this sensor to these tested gases, the scope of sensor heating-up temperature will comprise sensitive temperature.

Present embodiment is an example with identification and the concentration detection that commercial broad-spectrum combustible gas sensor QM-NG1 carries out methyl alcohol, ethanol, benzene and water vapor, and the present invention is described in detail.

See also Fig. 1,, mainly comprise sensor probe 1, modulus conversion chip 2, analog-digital chip 3, microprocessor 4 and display device 5 for the Electronic Nose schematic representation of apparatus that is used to realize detection method provided by the invention.This device can realize that also can use special-purpose ADC and DAC chip and various other little process chip such as single-chip microcomputer, dsp chip is realized with computing machine and data collecting card.Sensor probe structure in the Electronic Nose device as shown in Figure 1a, its heating module 9, thermistor 10 and sensor sensing film 11 are integrated in a SnO ₂On the sensor probe 12, only the sensitive membrane one side of thermistor 10 need be got final product near sensor sensing film during installation.10 of thermistors wherein use when debugging, can omit in the actual product.Sensor sensing film 11 and a sample resistance R during measurement _LoadSeries connection inserts test loop, R _LoadOn voltage drop be the output voltage (because sample resistance is known circuit common, therefore be not described specifically, also do not recommend accompanying drawing) of sensor.Fig. 1 b is the structural drawing of whole test system, and the temperature signal of sensor probe 1 respectively is connected with microprocessor 4 by an A/D interface with the voltage output signal, and the heating voltage control of sensor probe 1 is realized by a D/A interface.The data that collect are through obtaining identification and quantized result after the microprocessor processes, its result is by terminal presentation facility 5 (as display or registering instrument etc.) output testing result.

QM-NG1 type combustible gas sensor all has good response to water vapor and multiple organic volatile, is a kind of gas sensor of universal, and its temperature curve is seen Fig. 2.It is the closed container of 1500mL that sensor probe is placed a volume, is full of the air of clean dried in the container, and an injection orifice is arranged at container top, and detected material injects test container thus.

All between 200-250 ℃, select the temperature range of heating in view of the above is 100-400 ℃ to QM-NG1 type sensor to the sensitive temperature of methyl alcohol, ethanol, benzene and four kinds of gases of water vapor.

By the thermistor detected temperatures, the sensor probe corresponding temperature was about 100 ℃ when heating voltage was 2V, and heating voltage when being 8V corresponding temperature be about 400 ℃.Therefore can control heating voltage cycle between 3-8V change (as sine wave, triangular wave, sawtooth wave and other arbitrarily waveform all can), just can allow sensor temperature cycle between 100-400 ℃ change.Heating waveform used among this embodiment is

$V_{\mathrm{heat}}=5.0+3.0*\sin (2\mathrm{\&pi;}*\frac{\mathrm{<figure-callout\; id="400"\; label="t"\; filenames="C20051001210700082.png,C20051001210700091.png"\; state="\{\{state\}\}">t</figure-callout>}}{400}+\frac{\mathrm{\&pi;}}{4}).$

Sensor probe is placed the tested gas of standard of variable concentrations respectively, and the control of start-up routine temperature, the waveform of record sensor output, the result is as shown in Figure 3 and Figure 4.

The sensor output voltage curve is done differential calculation, obtain the pattern information of different tested gases, as shown in Figure 5 and Figure 6.According to the different pattern information of various tested gases, can discern these measured objects.

Logarithm with the concentration of tested gas is a transverse axis, is longitudinal axis mapping with the logarithm of sensor minimum resistance (this resistance value is corresponding to the peak value of output voltage in the heating process) in heating process, obtains a typical curve, as shown in Figure 7.

For tested gas, its temperature variation of heating Waveform Control with same obtains output voltage waveforms, and the pattern with the standard material standed for behind the differential contrasts, and judges that this measured object is exactly and the immediate material standed for of its pattern.According to the standard working curve of this material standed for, can obtain the concentration of measured object.

For increasing the accuracy of testing result, the present invention can also form a detection system by a plurality of the sensor probes, each sensor probe in this system independently detects, and microprocessor can obtain exporting more reliably according to the recognition result of each sensor after treatment.

Compare with traditional multisensor electric nasus system, the present invention can greatly reduce the number of sensor Order can keep high accuracy of identification simultaneously.

Claims (7)

1. one kind is detected the method for multiple gases with single-sensor, because the molecule of all gases has different chemical character, to make time spent output quantity changing pattern different with sensor, thereby realizes the detection of multiple gases; The steps include:

A) temperature programmed control is in one-period inner control temperature variation;

B) output voltage of real time record sensor;

D) the different tested gases of identification are at the serial output voltage curve of this sensor, to the calculating of differentiating of this series output voltage curve;

E) typical curve that obtains under the same terms with this gas calculates its concentration.

2. the multiple gases that the process of claim 1 wherein is by multiple organic or inorganic molecular composition.

3. the process of claim 1 wherein that range of temperature comprises the sensitive temperature interval of detected gas among the step a.

4. device that is used for the described method of claim 1, it mainly is made up of at least one sensor probe, microprocessor and recording unit; Wherein:

Sensor probe is provided with heating module and sensor sensing film;

Heating module is connected with computing machine respectively with sensor sensing film;

By said apparatus, microprocessor control sensor probe temperature, the output voltage of collection and processes sensor probe simultaneously.

5. the device of claim 4, wherein heating module is connected with computing machine by the D-A converter interface, and sensor sensing film passes through the analog-digital converter interface and is connected with computing machine.

6. the device of claim 4 wherein is pasted with thermistor on the sensor sensing film, and this thermistor is connected with computing machine by the analog-digital converter interface.

7. the device of claim 4, display device wherein is graphoscope, charactron, Liquid Crystal Module or loudspeaker.

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