酒精传感器MQ3介绍

MQ-3SemiconductorSensorforAlcoholSensitivematerialofMQ-3gassensorisSnO2,whichwithlowerconductivityincleanair.Whenthetargetalcoholgasexist,Thesensor’sconductivityismorehigheralongwiththegasconcentrationrising.Pleaseusesimpleelectrocircuit,Convertchangeofconductivitytocorrespondoutputsignalofgasconcentration.MQ-3gassensorhashighsensititytoAlcohol,andhasgoodresistancetodisturbofgasoline,smokeandvapor.Thesensorcouldbeusedtodetectalcoholwithdifferentconcentration,itiswithlowcostandsuitablefordifferentapplication.CharacterConfiguration*Goodsensitivitytoalcoholgas*Longlifeandlowcost*SimpledrivecircuitApplication*Vehicelalcoholdetector*PortablealcoholdetectorTechnicalDataBasictestloopTheaboveisbasictestcircuitofthesensor.Thesensorneedtobeput2voltage,heatervoltage（VH）andtestvoltage（VC）.VHusedtosupplycertifiedworkingtemperaturetothesensor,whileVCusedtodetectvoltage(VRL)onloadresistance（RL）whomisinserieswithsensor.Thesensorhaslightpolarity,VcneedDCpower.VCandVHcouldusesamepowercircuitwithpreconditiontoassureperformanceofsensor.Inordertomakethesensorwithbetterperformance,suitableRLvalueisneeded:PowerofSensitivitybody(Ps):Ps=Vc2×Rs/(Rs+RL)2ModelNo.MQ-3SensorTypeSemiconductorStandardEncapsulationBakelite(BlackBakelite)DetectionGasAlcoholgasConcentration0.04-4mg/lalcoholLoopVoltageVc≤24VDCHeaterVoltageVH5.0V±0.2VACorDCCircuitLoadResistanceRLAdjustableHeaterResistanceRH31Ω±3Ω（RoomTem.）HeaterconsumptionPH≤900mWSensingResistanceRs2KΩ-20KΩ(in0.4mg/lalcohol)SensitivitySRs(inair)/Rs(0.4mg/LAlcohol)≥5CharacterSlopeα≤0.6(R300ppm/R100ppmAlcohol)Tem.Humidity20℃±2℃；65%±5%RHStandardtestcircuitVc:5.0V±0.1V；VH:5.0V±0.1VConditionPreheattimeOver48hoursVcVHGNDRLVRLResistanceofsensor(Rs):Rs=(Vc/VRL-1)×RLSensitivityCharacteristicsInfluenceofTemperature/HumidityFig.1showsthetypicalsensitivitycharacteristicsofFig.2showsthetypicaltemperatureandhumiditytheMQ-3,ordinatemeansresistanceratioofthesensorcharacteristics.Ordinatemeansresistanceratio(Rs/Ro),abscissaisconcentrationofgases.Rsmeansofthesensor(Rs/Ro),Rsmeansresistanceofsensorresistanceindifferentgases,Romeansresistanceofin0.4mg/lalcoholunderdifferenttem.andhumidity.sensorin0.4mg/lalcohol.AlltestareunderstandardRomeansresistanceofthesensorinenvironmentoftestconditions.0.4mg/lalcohol,20℃/65%RHP.S.:Sensitivitytosmokeisignite10pcscigarettesin8m3room,andtheoutputequalsto0.1mg/lalcoholStructureandconfigurationStructureandconfigurationofMQ-3gassensorisshownasFig.3,sensorcomposedbymicroAL2O3ceramictube,TinDioxide(SnO2)sensitivelayer,measuringelectrodeandheaterarefixedintoacrustmadebyplasticandstainlesssteelnet.Theheaterprovidesnecessaryworkconditionsforworkofsensitivecomponents.TheenvelopedMQ-4have6pin,4ofthemareusedtofetchsignals,andother2areusedforprovidingheatingcurrent.Notification1Followingconditionsmustbeprohibited1.1ExposedtoorganicsiliconsteamOrganicsiliconsteamcausesensorsinvalid,sensorsmustbeavoidexposingtosiliconbond,fixature,siliconlatex,puttyorplasticcontainsiliconenvironment1.2HighCorrosivegasIfthesensorsexposedtohighconcentrationcorrosivegas(suchasH2Sz,SOX，Cl2，HCletc),itwillnotonlyresultincorrosionofsensorsstructure,alsoitcausesinceresensitivityattenuation.1.3Alkali,Alkalimetalssalt,halogenpollutionThesensorsperformancewillbechangedbadlyifsensorsbesprayedpollutedbyalkalimetalssaltespeciallybrine,orbeexposedtohalogensuchasfluorin.1.4TouchwaterSensitivityofthesensorswillbereducedwhenspatteredordippedinwater.1.5FreezingDoavoidicingonsensor’surface,otherwisesensorwouldlosesensitivity.1.6AppliedvoltagehigherAppliedvoltageonsensorshouldnotbehigherthanstipulatedvalue,otherwiseitcausedown-lineorheaterdamaged,andbringonsensors’sensitivitycharacteristicchangedbadly.1.7VoltageonwrongpinsFor6pinssensor,ifapplyvoltageon1、3pinsor4、6pins,itwillmakeleadbroken,andwithoutsignalwhenapplyon2、4pins2Followingconditionsmustbeavoided2.1WaterCondensationIndoorconditions,slightwatercondensationwilleffectsensorsperformancelightly.However,ifwatercondensationonsensorssurfaceandkeepacertainperiod,sensor’sensitivitywillbedecreased.2.2UsedinhighgasconcentrationNomatterthesensoriselectrifiedornot,iflongtimeplacedinhighgasconcentration,ifwillaffectsensorscharacteristic.2.3LongtimestorageThesensorsresistanceproducereversibledriftifit’sstoredforlongtimewithoutelectrify,thisdriftisrelatedwithstorageconditions.Sensorsshouldbestoredinairproofwithoutsilicongelbagwithcleanair.Forthesensorswithlongtimestoragebutnoelectrify,theyneedlongagingtimeforstbilitybeforeusing.2.4LongtimeexposedtoadverseenvironmentNomatterthesensorselectrifiedornot,ifexposedtoadverseenvironmentforlongtime,suchashighhumidity,hightemperature,orhighpollutionetc,itwilleffectthesensorsperformancebadly.2.5VibrationContinualvibrationwillresultinsensorsdown-leadresponsethenrepture.Intransportationorassemblingline,pneumaticscrewdriver/ultrasonicweldingmachinecanleadthisvibration.2.6ConcussionIfsensorsmeetstrongconcussion,itmayleaditsleadwiredisconnected.2.7UsageForsensor,handmadeweldingisoptimalway.Ifusewavecrestweldingshouldmeetthefollowingconditions:2.7.1Sol