基于单片机的氧气检测仪英文原版参考文献word版文档格式.docx

基于单片机的氧气检测仪英文原版参考文献word版文档格式.docx

《基于单片机的氧气检测仪英文原版参考文献word版文档格式.docx》由会员分享，可在线阅读，更多相关《基于单片机的氧气检测仪英文原版参考文献word版文档格式.docx（26页珍藏版）》请在冰豆网上搜索。

stabilisedopticaloxygensensor

AlbertoJ.Palmaa,JavierL´

opez-Gonz´

alezb,LuisJ.Asensioa,MariaDoloresFern´

andez-Ramosb,LuisFerminCapit´

an-Vallveyb,~

aDepartmentofElectronicsandComputerTechnology,CampusFuentenueva,FacultyofSciences,

UniversityofGranada,E-18071Granada,Spain

bSolidPhaseSpectrometryResearchGroup,DepartmentofAnalyticalChemistry,CampusFuentenueva,

FacultyofSciences,UniversityofGranada,E-18071Granada,Spain

Received26January2006;

receivedinrevisedform13March2006;

accepted14March2006

Availableonline5June2006

Abstract

Anovelmeasurementsystemcomprisedofaportableelectronicinstrumentwithanopto-chemicalsensorforatmosphericoxygensensingispresented.Opticalsensorsbasedonluminescencequenchinghavebeenthoroughlyinvestigatedinthesearchforsufficientsensitivityandhighstability.ThedyeplatinumoctaethylporphyrincompleximmobilisedinapolystyrenemembranewasselectedasanoxygenprobethatwasstabilisedwiththeheterocyclicamineDABCO,achievinginthiswayameandriftof0.01%oxygenconcentrationperday.Theportableinstrumentisbasedonamicrocontroller.Itsmainfeaturesare:

asingleopticalsensorchannel,lackofopticalfilters,fullydigitalsignalprocessing,autonomousoperationwithcomputercommunicationcapabilityforreprogramminganddatasavingandlowpowerconsumption.Theuseofadigitaloutputphotodetectormakesitpossibletoavoidanalogueprocessingwiththeconsequentcircuitrysavingandbetternoiseimmunity.Themeasuredparameterinthetransductionprocessisquitesimilartotheluminescencelifetime.Thetypicalmeasurementrangeisfrom0to30%oxygenandtheresponsetimeisbelow30sforfullrangeswing.Typicalinstrumentcharacteristicsaretemperatureeffectcorrection,lowdriftandanaccuracyof0.5%inoxygenconcentrationforthecollectivecalibrationcurve.Betteraccuracycanbeobtainedwithindividualsensorcalibration.Dimensionsandweightare110mm×

66mm×

28mmand95g（withoutbattery）,respectively.Poweringitwithastandard9VPP3batteryformorethan10daysofoperationispossible.

©

2006ElsevierB.V.Allrightsreserved.

Keywords:

Opticalchemicalsensor;

Oxygendetermination;

Phosphorescence;

Luminescencequenching;

Portableinstrument;

Microcontroller

1.Introduction

Thedevelopmentofportableanalyticalinstrumentationisaninterestinginterdisciplinaryareaofresearchwhichbringsanalyticalchemistsandelectronicengineerstogether.Tomanufacturelow-costeasy-to-useinstrumentsforuseindifferentfieldssuchastheenvironment,worksafety,defenceandhealth,muchmoretechnologicaldevelopmentmustbedone.Thiswilltakeanalyticalinstrumentationoutoftherealmofdedicatedacademicorresearchlaboratoriesandofferittonontrainedusersandconsumers.Greatresultshavebeenobtained

~Correspondingauthor.

E-mailaddress:

lcapitan@ugr.es（L.F.Capit´

an-Vallvey）.

inthisregardinsomeareassuchashealthcareandprocesscontrol.

Inenvironmentalsensing,inparticular,thedevelopmentofhand-heldbattery-operatedmeasurementsystemsforthedeterminationofoxygenisafieldofresearchwithwideapplications.Inthisarea,opticalchemicalsensorsareanattractivealternativetothemoreestablishedelectrochemicalsensors[1].Mostopticalchemicaloxygensensorsarebasedonthequenchingoftheluminescenceofanoxygen-sensitivedyebymolecularoxygen.Extensiveworkhasbeendoneinthisarea,whereavarietyofluminescentdyeshavebeenincorporatedintoagaspermeablemembraneanddifferentmeasurementprocedureshavebeenreported[2–6].Inthepast,instrumentationforsignalprocessingsuchasluminescencewasgenerallyfairlyelaborated,bulkyandcostlyandthereforeunsuitableforportable

630A.J.Palmaetal./SensorsandActuatorsB121（2007）629–638

2.1.Reagents

Platinumoctaethylporphyrin（PtOEP）wasobtainedfromPorphyrinProductsInc.（Logan,UT,USA）,1,4-diazabicyclo[2.2.2]octane98%（DABCO）,tetrahydrofuran（THF）,polystyrene（PS,averageMW280,000,Tg:

100~C,GPCgrade）andhighmolecularweightpoly（vinylchloride）（PVC）werepurchasedfromSigma–AldrichQu´

ımicaS.A.（Madrid,Spain）.SiliconeElastosilN-10wasobtainedfromGeneseePolymerCorp.（MI,USA）.Thefluopolymerpoly（isobutylmethacrylateco-tetrafluoropropylmethacrylate）wassynthesisedandcharacterisedbyusaccordingtoAmaoetal.[12].SheetsofMylar-typepolyester（Goodfellow,Cambridge,UK）wereusedasasupportformembranes.ThegasesO2andN2usedwereofahighpurity（>

99%）andweresuppliedingascylindersbyAirLiquidS.A.（Madrid,Spain）.

2.2.Membranepreparation

Themembraneswereproducedonapolyestersubstrateusingaspin-coatingtechnique.（i）Polystyrenemembranes:

mixturesforthepreparationofoxygen-sensitivemembranesweretypicallymadebydissolving0.5mgofPtOEPin1mLofasolutionof5%（w/w）ofPSinfreshlydistilledTHFinaglassvial.Themembraneswerecastbyplacing30~Lofthecocktailonathicktransparentpolyestersheetoftheappropriatesizeusingahomemadespin-coater[22]rotatingat180rpm.Afterspinningfor2min,themembranewasremovedfromthespincoateranddriedinadryerwithsaturatedTHFatmospherefor24hatroomtemperature.Thesensing6mmdiametercircularfilmthatwasobtainedishomogeneous,transparentandpinkincolourwithacalculatedthicknessofabout4.5~mandanapproximatePtOEPconcentrationof14.4mM.（ii）Polystyrene–DABCOmembranes:

inthiscase,thecocktailcontains12mgofDABCO（25%DABCO）inadditiontoothercomponentsindicatedabove.Thefilmobtainedusingthesametechniqueis10mmindiameterand14~minthickness.（iii）PVCmembranes:

themembraneswerecastusing50~Lofacocktailpreparedbydissolving0.5mgofPtOEPand100mgofPVCin1mLofTHFinaglassvial.Thefilmobtainedis6mmindiameterand5~mthick.（iv）Siliconemembranes:

thesemembraneswerepreparedwith30~Lofacocktailcontaining1gofsiliconeElastosilN-10in1mLoftoluene.ToimpregnatethemembranewithPtOEP,thetechniquedescribedbyBaconandDemas[23]wasused.Themembranewasimmersedina1000mgL-1solutionofPtOEPinCH2Cl2for10min.Itwasthenremoved,rinsedwithCH2Cl2andair-dried.Thefilmobtainedwas11mmindiameterand7~mthick.Allthepreparedmembraneswerestoredinthedarkuntilusetoavoidphotodegradation.

2.3.Measurementsystem

2.3.1.Portableelectronicinstrument

Ourmeasurementsystemconsistsofasensingmembranedirectlyattachedtoaportableelectronicinstrumentwitha

systems.However,thelasttwodecadeshavewitnessedsignifi-2.Experimental

cantdevelopmentofreliable,smallandlow-costsemiconductordevicesforexcitingandcollectingopticalsignals,suchashighintensitylightemittingdiodes（LED）,laserdiodesandsemiconductorphotodetectors.Thistechnologyhasbeencontinuouslyincludedinnewportableinstrumentdesigns,particularlyforgassensing.

Inthequenchingprocess,emittedluminescenceintensityandluminescencedecaytimeareaffectedbyoxygenconcentration.Fromthepointofviewofphotostabilityandimmunitytostrayopticalsignalinterference,decaytimemeasurementseemstobemoreadvantageousthanintensity[4,7].However,someresultshavebeenreportedincludingaportableinstrumentfordissolvedoxygendetectionbasedonintensitymeasurement[2,8].Thedecaytimeoftheluminescencecanbedeterminedwithdifferentmethods:

（i）directmeasurementwithhighspeed,largeandexpensiveinstrumentation[9]and（ii）phasemodulationtechniques[2,10].Inthelatterapproach,dedicatedsignalprocessingelectronicshasmadeaninstrumentthatincludesdualopticalchannels,circuitryfortheacsignalandseveralcontrolcircuitsforphaseshiftcorrectionandavoidingamplifiersaturation[7].

Oneofthetypicalproblemsofquenching-basedsensorsforoxygen,especiallyforintensity-basedsensors,istheusuallowphotochemicalstabilityofluminophoreswhichreducesthelifeofthesensorandrequiresfrequentrecalibration.Differentsolutionshavebeendevisedtosolvetheproblem:

（1）modifyingexistingluminophores[11];

（2）modifyingthepolymermatrices[12];

（3）usingrelativesignalsobtainedindifferentways:

（a）fromscatteredexcitationradiation[13],（b）fromtheluminophoreitselfthroughaluminescencebandinsensitivetoO2[14,15]orbyusingaluminophorethatsimultaneouslyshowsphosphorescencequenchablebyO2andfluorescenceinsensitivetoO2[16],（c）fromasecondO2-insensitivefluorophorewithsimilardecayratessuchasindicatordyes[17,18];

（4）introducingstabiliseradditives,mainlytertiaryamines,tomembranestoremovethereactivesingletoxygengivenofffromthequenchingprocessofluminophoreluminescence[19,20].

Inthisreport,aportableinstrumentforatmosphericoxygenconcentrationmeasurementhasbeendeveloped[21].Ourgoalswereareliable,simple,low-costprototypeincludingahighstabilisedsensingmembraneandthelatestsemiconductoroptoelectronicdevices.Wereportonaneasy-to-usemeasurementsystemwithhighopticalandelectricalinterferenceimmunity,extremelysimplesignalprocessingcircuitry,lowpowerconsumptionandenoughaccuracyforinsituatmosphericoxygendetermination.Wehavedesignedaninstrumenttoovercomesomeofthedrawbacksofpreviousportabledesigns,basedonsimpleelectronicsandaonesignalchannelwithoutanyreferencechannel.Oneofthemainadvantagesofourdes