Aeriform sensor is a kind of Jiang Mou kind the converter that aeriform bulk mark changes into corresponding and telegraphic date. Exploration head undertakes recuperating to aeriform sample through aeriform sensor, include filter to remove foreign matter and interference normally gas, dry or refrigeration processing appearance shows a share. Aeriform sensor is in the air conditioning that with family expenses day warning apparatus of gas of propane of · burning gas gives priority to and air are clean implement, the domain such as the car gets extensively applied. Labour collects a net now small make up pair of Figaro most check-up of adept 3 kinds of gas measures a principle to undertake demonstrative.

 

The framework with semiconductor gas simple sensor

 

 

STEP1

 

In clean air, the oxygen of adsorption of oxidation stannum surface can manacle the electron in oxidation stannum, create the position that the electron flows hard.

 

STEP2

 

The gas in leak (reducing gas) in the environment, after exterior oxygen and reductive gas react, disappear, the electronic recovery in oxidation stannum is free, suffer this effect, electronic flow unobstructed.

 

Of semiconductor gas sensor detect principle

 

Expose below the temperature that counting Baidu when oxidation stannum particle when oxygen is medium, after oxygen catchs the electron in particle, adsorptive at particle surface. Result, electronic depletion layer is formed in oxidation stannum particle. The oxidation stannum particle that uses as a result of aeriform sensor is general very small, because this is in air,whole particle will enter the state of electronic depletion layer. This kind of condition calls a look to fail (Volume Depletion) . Contrary, the condition that fails particle center place to achieve depletion layer calls region to fail (Regional Depletion) . Make aerobic cent is pressed from 0 (Flat Band begins according to small ([O-](Ⅰ ) ) in → ([O-](Ⅱ ) ) → is big ([O-](Ⅲ ) ) ) when rising orderly, can take structure and electron to conduct the change that distributing following plan institute show ([O-] : Adsorptive aerobic chroma) . Fail in the look (Volume Depletion) below condition, the ply change of electronic depletion layer ends, generation Fermi energy level changes PkT, the electron is extinct condition advances a PkT to increase forth, back down a PkT is contractible.

 

■ the extinct position that increases semiconductor particle as adsorptive aerobic chroma is being advanced can take a structure

 

 

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Conduct an electron to distributing

 

 

[E]: ? D: of Qu of Qian actor ǘ ? Does ┳ use Du?

 

The look fails (Volume Depletion) the electronic chroma of surface of particle of bulbiform oxidation stannum below condition [A of radius of Nd of density of E]S usable Shizi, particle and heart do obeisance to length LD to adopt posture (1) express. If P increases criterion [E]S decreases, p decreases criterion [E]S increases.

 

[E]S=Nd Exp{-(1/6)(a/LD)2-p} . . . (1)

 

The resistance R of the sensor that spends composition of identical particle of bulbiform oxidation stannum by size, Shi Zimi, can use the resistance R0 when Flat Band, through posture (2) express. [E]S decreases to will increase, [E]S increases to will narrow.

 

R/R0= Nd/[e]S. . . (2)

 

Used the sensor of semiconductor type gas of oxidation stannum, pass surface of oxidation stannum particle so namely [the change that the change of O-] will come to reflect resistance R.

 

Be heated to count the oxidation stannum particle of Baidu in park air, once expose at carbon monoxide in such reducing gas, after its surface produces reaction between adsorptive oxygen and gas, make [O-] decreases, the result is [E]S increases, r is contractible. After removing reducing gas, [O-] increases to expose at the chroma before gas, r also will restore to expose at the size before gas. The sensor of semiconductor type gas of use oxidation stannum uses this individual character to be able to undertake detecting to gas namely.

 

Bibliographical reference: Noboru Yamazoe, kengo Shimanoe, basic Approach To The Transducer Function Of Oxide Semiconductor Gas Sensors, sensor of gas of type of catalytic combustion of Sensors And Actuators B 160 (2011) 1352-1362 detects principle

 

Sensor of gas of catalytic combustion type is detected by what have reaction to can burning gas piece (D) and do not compensate with what can light gas to have reaction piece (C) 2 component are formed. If existence can burn gas, detect only piece can burn, because this detects a temperature rise make detect piece resistor increases. Contrary, because compensate piece do not burn, its resistor does not produce change (graph 1) . These component comprise Huisi to connect bridge loop (graph 2) , nonexistent in the atmosphere that can burn gas, can adjust alterable resistor (VR) let bridge loop be in balance position. Next, in exposing Yuke to burn gas when aeriform sensor when, detect only piece resistor rises, because the balance of this bridge loop is broken, this change expression is disequilibrium voltage (Vout) and can be detected to come out. The scale that 3 put in the graph to show between this disequilibrium voltage and aeriform chroma concerns, because this can be passed,determine voltage and check gives aeriform concentration.

 

■ (graph 1) determines circuit

 

 

■ (graph 2) tests circuit

 

 

■ (graph 3)

 

 

Electrochemistry gas sensor: Sensor component is formed with electrode reaction type

 

 

Sensor is detected by what come from noble metal catalyst extremely, extremely right conduct body to form with ion. Wait when CO detect when object gas exists, detecting extremely with air medium vapor happens on activator (1) the reaction that type place shows.

 

CO + H2O→CO2 ＋ 2H+ + 2e- … (1)

 

Detect extremely with extremely right receive electrify to flow (short circuit) hind, detect extremely the proton of generation (H+) and the electron that arise at the same time (E- ) conduct body and exterior electrical wiring through ion respectively (down-lead) arrive severally extremely right, be opposite extremely on with air happen between medium oxygen (2) the reaction that type place shows.

 

(1/2) O2 + 2H+ + 2e-→H2O … (2)

 

That is to say this sensor was formed by (1) (2) reaction type forms (3) the complete batteries reaction of reaction type, can consider as the batteries that regards active material as gas.

 

CO + (1/2) O2→CO2 … (3)

 

When doing aeriform sensor to use, put through detect extremely with extremely right electric current, will determine its short-circuit current.

 

CO chroma detects the principle is formulary

 

 

Convection crosses the short-circuit current of exterior circuit and relation of aeriform pH indicator, have proper diffusion control through sensor (the afflux that controls gas is measured) , present a posture (4) such scale concerns (right graph) .

 

I = F×(A/σ )×D×C×N … (4)

 

Here I: Short-circuit current; A: Diffuse aperture area; σ : Diffusion layer length; D: Aeriform diffusion coefficient; C: Aeriform chroma; ｎ : The electronic amount of reaction

 

Specialty

 

Reaction type (1) because shows oxidation potential compares the fiducial cost of oxidation electrode potential (2H+ + 2e- ? H2) wants low (have inferior potential) , accordingly this reaction does not need to use up come from external the other energy such as voltage, temperature, can undertake selectively, with other detect means photograph disturbs respect of report of gender, repeatability, section to want to be gotten primely than be in much.

 

Aeriform sensor uses requirement and note

 

The product technology material of Figaro company is sure to read please when using, undertake affirming to product standards and use condition.

 

Should notice to avoid to go up when circuit when the design other electron component short-circuits, the voltage that exceeds rating, electric current and temperature are brought to aeriform sensor when the unusual situation such as open circuit.

 

Should notice to avoid to affect other parts because of the breakdown of aeriform sensor when the design, direct or bring about the machine that used aeriform sensor secondhand generation misoperation, fumy, on fire or other and flabby decided position, make the security of the machine is damaged.

 

If be necessary, consider to adopt a setting to be similar to protective circuit please such breakdown protects a safety precaution.

 

About using safe note

 

About using tension

 

If aeriform sensor was brought to bear on to exceed the voltage of rating, the circumstance that although did not appear,line and content reason injure, produce the situation that sensor character is affected likely also. Once aeriform sensor has overvoltage experience, do not want to use please.

 

About using temperature

 

Do not want to use aeriform sensor below the high temperature that exceeds rated temperature please. Below the high temperature environment that exceeds rated temperature electrode film is met deterioration, the character of sensor can be affected very likely.

 

About using an environment

 

If aeriform sensor gets the pollution of alkali metal, the character of aeriform sensor is affected significantly likely. Want escape brine sparge especially.

 

If expose,at ammonia the alkalescent Gao Nong such as gas spends gas in, the character of aeriform sensor is affected very likely, because this should avoid,appear such circumstance.

 

Should avoid to using dirt of balata of silicon binder and the fixature that contain silicon, silicon, silicon likely child the place is used or custodial gas sensor. The silicon vapour that sends from the product evaporate that contains silicon causes what sensor interior gas flows into a passageway to jam likely.

 

If aeriform sensor interior and surface written guarantee for long in great quantities continuously if showing, may cause what gas flows into a passageway to jam the deterioration circumstance of as subtle as gas film happens. The slight knot of the generation in normal indoor environment shows pair of gas sensor to won’t produce major effect.

 

If aeriform sensor is exposed at vulcanization hydrogen and vitriolic department when gas atmosphere, appear likely internal aeriform diffusion barrier and lid cap, or noumenon is corroded, the circumstance that aeriform sensor is damaged.

 

If aeriform sensor is exposed at alcohol kind, in the organic matter vapour of the generation such as acetone, naphtha, sensitive ministry adsorption has gas machine content vapour, may produce the situation that sensor character short time varies.

 

If aeriform sensor is exposed in exceeding dust and oily gas mist, produce the situation that eyelet jams in aeriform sensor interior likely. If can foretell,be such use environment, the proposal is added in the upside of aeriform sensor filter is received outside outfit.

 

When the situation that produces fast quick-freeze form in microtherm environment, aeriform sensor interior may happen slack produce an effect to the character of aeriform sensor. Should set Gai Maochao especially when park machine is medium, very incidental such circumstance.

 

If why be handled

 

Do not want please sensor water intrusion medium, or sprinkle water to sensor, cause an effect to the character of sensor likely otherwise.

 

If let aeriform sensor shake strongly or be bumped, its interior may produce the situation such as line or short circuit.

 

Do not decompose aeriform sensor at will please, also do not make place of noumenon and lid cap happens be out of shape.

 

About custodial method

 

If place aeriform sensor,be in if sealed bag keeps inside the container with so airtight very strong sex, because of all round the case that likelihood occurrence knot shows the interior of metabolic gas sensor of temperature.

 

The design uses the note when the machine

 

The water in the cistern when the low temperature under occurrence zero writtens guarantee ice is frozen likely, freeze usually won’t produce an effect to the character of aeriform sensor, but the bulk after water is frozen increases to make aeriform sensor body produces metabolic circumstance to appear likely. After when designing a machine, wanting to notice to prevent aeriform sensor to be out of shape because of freezing, be in with configuration the other electron product all round and circuit substrate produce a contact.

 

Install the note when

 

When receiving sensor solder circuit substrate with soldering tin, if use soldering tin chamfer, the high concentration that soldering tin produces aids welding flux vapour to produce an effect to sensor character likely. We suggest hand solder is operated. The consideration uses the word of soldering tin chamfer, the influence that uses test group to arise possibly to sensor character beforehand in quantity antenatal please undertakes affirming.

 

It is those who raise pair of humidity to be able to bear or endure suffer gender, right of gas when be able to bear or endure to suffer a gender and use colophony film, the chemical composition dissolvent that colophony place contains may cause the circumstance that character drops to happen.