CN105403596A - Portable gas detection system based on nanometer compound material - Google Patents
Portable gas detection system based on nanometer compound material Download PDFInfo
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- CN105403596A CN105403596A CN201510717046.XA CN201510717046A CN105403596A CN 105403596 A CN105403596 A CN 105403596A CN 201510717046 A CN201510717046 A CN 201510717046A CN 105403596 A CN105403596 A CN 105403596A
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Abstract
The invention discloses a portable gas detection system based on a nanometer compound material. According to the portable gas detection system disclosed by the invention, a micromechanical processing method is adopted for preparing an interdigital electrode on a base; a layer of nanometer compound material is covered on the surface of the base and is used as a gas-sensitive coating, so that a gas sensor element is formed; a peripheral circuit is externally connected with the gas sensor element; the peripheral circuit comprises five parts, namely, a power supply, a signal conditioning circuit, a digital-to-analogue conversion circuit, a microprocessor control unit and an upper computer; and the portable gas detection system used for detecting gas is formed by the gas sensor element and the peripheral circuit. The portable gas detection system disclosed by the invention is simple in structure, is high in sensitivity and low in limit of detection, and can be widely applied to the detection and alarm for the gas at room temperature.
Description
Technical field
The present invention relates to a kind of gas detecting system of field of gas detection, be specifically related to a kind of portable gas detection system based on nano composite material.
Background technology
Gas sensor is used to detect the composition of gas and the sensor of content.Along with the development of nanometer technology, the gas sensor based on nano composite material obtains incremental advances.Wherein various metal oxide semiconductor nano-material and carbon nanomaterial etc. have all been used for building gas sensor separately.But single metal oxide semiconductor nano-material is difficult at room temperature produce response to gas, the response effect of carbon nanomaterial at room temperature for gas is then not satisfactory.Gas detecting system effectively can detect concentration and the classification of gas, prevents the harmful poisonous gas be strayed in environment from damaging.It mainly utilizes gas sensor to carry out the gaseous species existed in testing environment.
Summary of the invention
The present invention is directed to the deficiency in prior art, provide a kind of portable gas detection system based on nano composite material, at room temperature can carry out remote real time monitoring to gas, there is high response and low detectability.
The present invention is achieved through the following technical solutions:
Based on a portable gas detection system for nano composite material, be made up of gas sensor and peripheral circuit.
Gas sensor comprises substrate, interdigital electrode and air-sensitive coating, and interdigital electrode is positioned on substrate, and air-sensitive coating refers to and covers interdigital electrode surface and can carry out the nano composite material of reacting with object gas.
Preferably, substrate is the one among silicon base, polymeric substrates, ceramic bases or sapphire substrates.
Preferably, interdigital electrode is obtained by miromaching, and the positive and negative electrode spacing of interdigital electrode is 300 ~ 800 μm, and adjacent two inter-digital electrode pitch are 100 ~ 500 μm.
Preferably, nano composite material is composited by metal oxide nano-material and carbon nanomaterial, metal oxide nano-material is the one among zinc paste, tin ash, cuprous oxide, iron oxide, ceria, and carbon nanomaterial is the one among carbon nano-tube, Graphene, C60.The mass percent of metal oxide nano-material and carbon nanomaterial is the one in 50:50,60:40,70:30,80:20 or 90:10.
Peripheral circuit comprises following five parts:
Signal conditioning circuit: nurse one's health the change in resistance signal that gas sensor produces by target gas levels affects, makes change in resistance signal be converted into voltage signal.
Preferably, the change in resistance signal that signal conditioning circuit utilizes Wheatstone bridge to be produced by gas sensor is converted into micro voltage amount signal, and micro voltage amount signal nurses one's health into voltage signal through amplifying circuit again.Amplifying circuit adopts instrument amplifier, and reference voltage is provided by voltage stabilizing chip.
D/A converting circuit: voltage signal is converted into digital signal, so that follow-up data processing.
Preferably, D/A converting circuit adopts analog-digital converter, and the system clock of analog-digital converter is provided by microprocessor control unit.
Host computer: installed the computing machine of operating system, realizes the real-time monitoring to detection system.The serial ports of computing machine is connected with the serial ports of microprocessor by bluetooth transceiver therein, follows general single chip communications protocol and communicates.
Preferably, host computer utilizes Design of Monitoring and Control System software to design monitored picture.Show in real time containing historical text figure, gas concentration in monitored picture, sleep pattern button, cut-off button, alarm lamp, adjustment high alarm setting vernier etc.
Microprocessor control unit: be responsible for data acquisition, data processing and man-machine interaction, and communicate with host computer.The collection of data acquisition cardinal index mode convertion value.The microprocessor adopted need have programmable clock out function.
Power supply: be divided into mimic channel power supply and digital circuit power source two parts, the separately power supply of mimic channel power supply and digital circuit power source, mimic channel power supply is used for the power supply of signal conditioning circuit and D/A converting circuit simulation part, and digital circuit power source is used for the power supply of D/A converting circuit numerical portion and microprocessor control unit.Because signal conditioning circuit relates to small and weak signal, so higher to the power requirement of mimic channel, the noise of power supply is little as much as possible.In the Power Management Design of this system, adopt the separately power supply of mimic channel and digital circuit, the noise effect mimic channel produced to avoid digital circuit.
Power supply makes the energy by battery, coordinates the voltage needed for voltage stabilizer output.In order to realize long-range power-off, switch sections have employed relay latching circuit.
Be described further below with reference to the technique effect of accompanying drawing to design of the present invention, instantiation and generation, to understand the present invention fully.The object providing these to illustrate only is to help to explain the present invention, should not be used for limiting the scope of claim of the present invention.
Accompanying drawing explanation
Fig. 1 is the low power stereoscan photograph of zinc oxide nanowire-graphene composite material prepared by a preferred embodiment of the present invention.
Fig. 2 is the high power stereoscan photograph of zinc oxide nanowire-graphene composite material prepared by a preferred embodiment of the present invention;
Fig. 3 is the gas sensor component structure schematic diagram of portable gas detection system prepared by a preferred embodiment of the present invention;
Fig. 4 is the circuit theory diagrams of portable gas detection system prepared by a preferred embodiment of the present invention;
Fig. 5 is the microprocessor read-write ADS1210 program flow diagram of portable gas detection system prepared by a preferred embodiment of the present invention;
Fig. 6 is the microprocessor program process flow diagram of portable gas detection system prepared by a preferred embodiment of the present invention;
Fig. 7 is the system chart of portable gas detection system prepared by a preferred embodiment of the present invention;
Fig. 8 is that the portable gas detection system prepared of a preferred embodiment of the present invention is at room temperature to the response curve of 50ppm concentration ammonia;
Fig. 9 is that the portable gas detection system prepared of a preferred embodiment of the present invention is at room temperature to the response curve of variable concentrations ammonia.
Embodiment
Elaborate to embodiments of the invention below in conjunction with accompanying drawing, the present embodiment is implemented under premised on technical solution of the present invention, give detailed embodiment and concrete operating process, but protection scope of the present invention is not limited to following embodiment.
Be 0.5g zinc oxide nanowire by massfraction respectively, the graphene oxide of 0.1g polyvinylpyrrolidone and 0.5g is dissolved in the deionized water of 50ml, mix and blend 1h, is centrifugally placed on 50 DEG C of dry 24h in vacuum drying oven for 3 times, obtains zinc oxide nanowire-graphene oxide composite material.The compound substance obtained is carried out the annealing thermal treatment under argon shield, annealing temperature is 300 DEG C, and annealing time is 30min, obtains zinc oxide nanowire-graphene composite material.With the concentration of 1mg/L, the powder of this compound substance is joined in deionized water, with 40KHz ultrasonic process 10min, make compound substance in a solvent dispersed, thus obtain the dispersion liquid of zinc oxide nanowire-graphene composite material.Get 1 μ L compound substance dispersant liquid drop to interdigital electrode surface, vacuum drying 1h, thus obtain gas sensor components and parts.Fig. 1 and Fig. 2 is the stereoscan photograph of zinc oxide nanowire-graphene composite material, and Fig. 3 is the gas sensor components and parts schematic diagram of portable gas detection system of the present invention.
Fig. 4 is circuit theory diagrams, and because the desired operating voltage of sensor is near 0.05 ~ 0.1V, R7, R8 divider resistance all gets 100K.RW is 5K potentiometer, is used for adjustment point.The 2.5V reference voltage that electric bridge is obtained by REF1004 voltage stabilizing drives, and electric bridge two check point current potential is clamped near 2.5V.Amplifying circuit adopts instrument amplifier AD620.The 1.25V that the reference voltage of AD620 is obtained by REF1112 voltage stabilizing provides.The signal condition of sensor is become the voltage signal of 1.25 ~ 3.75V by signal conditioning circuit, mates the input of analog-digital converter.AD620 regulates gain by high precision 2K potentiometer RG, by the range of its adjustable whole sensor.
D/A converting circuit adopts ADS1210 converter.ADS1210 is that single+5V powers, and has inside/outside reference voltage and inner self-calibration system.Because using ADS1210 internal reference voltage effect undesirable, adopting outside 2.5V reference voltage, being provided by REF1004 voltage stabilizing.ADS1210 inverting input is connected to 2.5V reference voltage, and its programmable amplifier enlargement factor is set to 4, converter input voltage range is arranged to 1.25 ~ 3.75V, matches with the output voltage of signal conditioning circuit.The system clock of ADS1210 is provided by microprocessor output clock.Fig. 5 is microprocessor read-write ADS1210 program flow diagram.
Microprocessor control unit STC10F08XE, as the control core of sensing system, is responsible for the collection of AD conversion value, data processing, and communicates with host computer.STC10F08XE has programmable clock out function, and as Fig. 3, clock exports CLKOUT1 (T1/P3.4) and provides system clock for ADS1210.Fig. 6 is microprocessor program process flow diagram.
According to the peripheral circuit of the system chart design detection system of Fig. 7, the power supply of mimic channel adopts MAX666 chip, 5V micropower regulator able to programme, exports 5V voltage.The shutdown pin of MAX666 can control to open (<0.3V)/closedown (>1.4V) voltage by CMOS logic level and export V
out.Utilize this function can export to reduce power consumption by the voltage of programming Control MAX666 in sleep pattern.MAX666 also has low-voltage monitoring function, when the current potential of pin LBI is lower than internal reference voltage 1.3V, and pin LBO level step-down.The voltage that can arrange more than any reference voltage by carrying out electric resistance partial pressure to input voltage is threshold value, and the voltage threshold of setting can be calculated by following formula:
Wherein V
bATTfor the voltage threshold expected, R9 and R10 is the divider resistance of input voltage.Be logic level in digital circuit, fault-tolerant ability is strong, therefore power requirement is low, so adopt the most frequently used LM7805 Three-end voltage stabilizer to export 5V.Because Operation system setting sleep pattern is to reduce power consumption, therefore with IRLML6401, P type metal-oxide semiconductor fieldeffect transistor, as the break-make of gate-controlled switch by programming Control D/A converting circuit digital power.
Fig. 8 is the response curve of portable gas detection system to 50ppm concentration ammonia, and can find that the response of sensor to 50ppm concentration ammonia reaches 7.2%, the response time is less than 50s, and release time is less than 200s.
Fig. 9 is the response curve of portable gas detection system to variable concentrations ammonia, and along with the increase of ammonia molecular conecentration, the response of sensor strengthens gradually, and minimal detectable concentration can be low to moderate 500ppb.
More than describe preferred embodiment of the present invention in detail.Should be appreciated that those of ordinary skill in the art just design according to the present invention can make many modifications and variations without the need to creative work.Therefore, all technician in the art, all should by the determined protection domain of claims under this invention's idea on the basis of existing technology by the available technical scheme of logical analysis, reasoning, or a limited experiment.
Claims (9)
1. based on a portable gas detection system for nano composite material, it is characterized in that, described detection system is made up of gas sensor and peripheral circuit;
Described gas sensor comprises substrate, interdigital electrode and air-sensitive coating, and described interdigital electrode is positioned on described substrate, and described air-sensitive coating refers to and covers described interdigital electrode surface and can carry out the nano composite material of reacting with object gas;
Described peripheral circuit comprises:
Signal conditioning circuit: the change in resistance signal that described gas sensor produces by described target gas levels affects is nursed one's health, makes described change in resistance signal be converted into voltage signal;
D/A converting circuit: described voltage signal is converted into digital signal, so that follow-up data processing;
Host computer: installed the computing machine of operating system, realizes the real-time monitoring to described detection system;
Microprocessor control unit: be responsible for data acquisition, data processing and man-machine interaction, and communicate with described host computer;
Power supply: be divided into mimic channel power supply and digital circuit power source two parts, the separately power supply of described mimic channel power supply and described digital circuit power source, described mimic channel power supply is used for the power supply of described signal conditioning circuit and described D/A converting circuit simulation part, and described digital circuit power source is used for the power supply of described D/A converting circuit numerical portion and described microprocessor control unit.
2. a kind of portable gas detection system based on nano composite material according to claim 1, it is characterized in that, described substrate is the one among silicon base, polymeric substrates, ceramic bases or sapphire substrates.
3. a kind of portable gas detection system based on nano composite material according to claim 1, it is characterized in that, described interdigital electrode is obtained by miromaching, the positive and negative electrode spacing of described interdigital electrode is 300 ~ 800 μm, and adjacent two described inter-digital electrode pitch are 100 ~ 500 μm.
4. a kind of portable gas detection system based on nano composite material according to claim 1, it is characterized in that, described nano composite material is composited by metal oxide nano-material and carbon nanomaterial, described metal oxide nano-material is the one among zinc paste, tin ash, cuprous oxide, iron oxide, ceria, and described carbon nanomaterial is the one among carbon nano-tube, Graphene, C60.
5. a kind of portable gas detection system based on nano composite material according to claim 4, it is characterized in that, the mass percent of described metal oxide nano-material and described carbon nanomaterial is the one in 50:50,60:40,70:30,80:20 or 90:10.
6. a kind of portable gas detection system based on nano composite material according to claim 1, it is characterized in that, the described change in resistance signal that described signal conditioning circuit utilizes Wheatstone bridge to be produced by described gas sensor is converted into micro voltage amount signal, and described micro voltage amount signal nurses one's health into described voltage signal through amplifying circuit again.
7. a kind of portable gas detection system based on nano composite material according to claim 6, is characterized in that, described amplifying circuit adopts instrument amplifier, and reference voltage is provided by voltage stabilizing chip.
8. a kind of portable gas detection system based on nano composite material according to claim 1, it is characterized in that, described D/A converting circuit adopts analog-digital converter, and the system clock of described analog-digital converter is provided by described microprocessor control unit.
9. a kind of portable gas detection system based on nano composite material according to claim 1, it is characterized in that, described host computer utilizes Design of Monitoring and Control System software to design monitored picture, show in real time containing historical text figure, gas concentration in described monitored picture, sleep pattern button, cut-off button, alarm lamp, adjustment high alarm setting vernier.
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| CN106525915A (en) * | 2016-09-30 | 2017-03-22 | 山东师范大学 | Support vector machine based foamed graphene sensor sample detection method and system |
| CN107991351A (en) * | 2017-11-17 | 2018-05-04 | 中国电子科技集团公司第四十八研究所 | Integrated hydrogen gas sensor and preparation method thereof |
| CN108088876A (en) * | 2017-12-29 | 2018-05-29 | 扬州大学 | It is a kind of can thermometric air-sensitive film test device and its application method |
| CN109839408A (en) * | 2017-11-24 | 2019-06-04 | 中国科学院大连化学物理研究所 | It is a kind of using nanocomposite as the ammonia gas sensor of sensing membrane |
| CN111793393A (en) * | 2020-06-29 | 2020-10-20 | 重庆第二师范学院 | Nanocomposite material, glassy carbon composite electrode, manufacturing methods of nanocomposite material and glassy carbon composite electrode, and electrochemical sensor |
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| CN109839408A (en) * | 2017-11-24 | 2019-06-04 | 中国科学院大连化学物理研究所 | It is a kind of using nanocomposite as the ammonia gas sensor of sensing membrane |
| CN108088876A (en) * | 2017-12-29 | 2018-05-29 | 扬州大学 | It is a kind of can thermometric air-sensitive film test device and its application method |
| CN111793393A (en) * | 2020-06-29 | 2020-10-20 | 重庆第二师范学院 | Nanocomposite material, glassy carbon composite electrode, manufacturing methods of nanocomposite material and glassy carbon composite electrode, and electrochemical sensor |
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Application publication date: 20160316 |