OpticalFluorescenceandItsapplicationtobloodglucosemonitor

OpticalFluorescenceandItsapplicationtobloodglucosemonitorPanYongfeng(WuhanUniversityofTechnology,Wuhan,China,xhyzjiji@126.com)Abstract—Bloodglucosemonitorsystemisdesignedwiththecoreofphotoniccrystalfiber(PCF)andtechnologyofsmall—invasivephotoelectric.Accordingtotheprinciplethatdifferentbloodglucoseconcentrationabsorbsdifferentlight,opticalmodulationiscontrolledbyMSP430．Lightisemitedtothebloodsamplesthroughtransmissionofthreeprobefiber—opticsensor.ThereflectedlightisinputedtoMSP430afterphotoelectricconversion.BloodglucoseconcentrationiscalculatedafterA/Dconversion.Thesystemhascharacteristicsofeasy—operation,lowenergy.Keywords—photoniccrystalfiber(PCF);small—invasive;bloodglucoseINTRODUCTIONiththerapiddevelopmentofscienceandtechnology,opticalfiberhasincreasinglyexpandedinthemedical,communications,Welectronicsandelectricity,andotherfields.Itisbecomingthebasisofpromisingmaterials.Inpractice,however,theopticalfiber,asatransmissionmediumtowirewillinevitablyneedtobebended.Whentraditionalopticalfibersareofbending,bendinglosswillaffectthesignaltransmissionpropertiesandsensitivity.Photoniccrystalfiber(photoniccrystalfiber,PCF)isanewtypeofopticalfiber,whichisformedbyasinglemedium,cladintwo-dimensionalphotoniccrystalsstructure.Itisdifferentfromthetraditionalopticalfiberbecauseofitssmallbendingloss,Opticalfiberfeaturesstableetc.Basedonthis,thebloodglucosemonitorsystemusePCFasopticalwaveguidematerialsanddesignethethreeprobebeamPCFsensortomonitorbloodglucose.Thesystemhashighprecision,lowcost,goodportability.II.DESIGNPRINCIPLESMeasuringprincipleTheglucoseinthebloodwillbeoxidatedandfinallyturnintodelta-gluconolactonebyGOD,whenthebloodsampledropsintothetestpaperwhichcontainsoxidasefortheoxidationofglucose.Thissubstancereactswithperoxidaseinthereagent,andthenwillgeneratealight-absorbingmaterial.Weplacethepaperinthereflectiveintensitymodulationtypefiberopticsensorintheopticalpath,asshowninfigure1.Thewholesensorsystemincludesalightsource,opticalfiber,opticalfiberandopticaldetectors.Thelightemittedbylightsourcereachthesurfaceofbloodsamplethroughthefilterandtransmittingfiber.Duetomaterialsuctionlightmodulation,reflectedlightwithbloodsugarinformationwillbereceivedbyreceivingopticalfiber,finallyturnedintoelectricalsignalsbythephotoelectricreceiverconverts.Whenthepoweroflightsourceandopticalfiberprobeandthedistancebetweenthereflectivesurfacesremainunchanged,thereceivingopticalfiberreceivesacertainwavelengthoflightintensityandthewavelengthofincidentlightintensityistheratioofthecorrespondingrelationshipwithbloodsugarlevels.Accordingtothelightintensityofthesignal,thebloodglucoseconcentrationcanbecalculated.Butthemaindrawbackofthiskindofopticalfibersensorismeasurementerrorcausedbylightsource,opticalpowerchangeswhenlightexcitationisnotstable.Inaddition,thedifferentreflectivityofthereflectorsurfaceandlighttransmissionlossintheopticalfibershouldalsocausemeasurementerror.Therefore,toputforwardthreeprobefiberopticsensorcompensationmeasuringmethodcaneliminatetheinfluenceofallkindsofunstablefactorsinthemeasuringenvironment.Figure1.ReflectiveintensitymodulationtypefiberopticsensorThreeprobecompensatingopticalfiberbundlesensorsmeasurementprincipleTraditionalreflectiveintensitymodulationtypefiberopticsensorusingasingleopticalfibertransmittingandreceivingthelightenergyisveryweak.Moreover,inthedesignofwiring,becauseofthewarpedshapechangethegeometryofthesymmetryofthefiberandtherelativerefractiveindexoffibercoreandcladding,whichaffectthelateraldistributionoftheopticalfibermodefield,anddestroythetotalreflectionoflightwavesalongtheopticalfibertransmissionconditions,leadtolightleakedtothepacketlayerandouterlayermedium.Therefore,thisdesigniscomposedofthreeprobeofopticalfibersensorincludingPCFwhichusetosendandreceivelightandtheadditionalreferencelightpath,asshowninfigure2.Figure2.ThreeprobeopticalfiberbundlesensorsOrdinarysinglemodeopticalfiberlosstheoryofimprovementscanbeappliedtoPCF,gaussianbeamstransmitalongtheopticalfiber,therelationshipbetweenlightintensityandbendlosscoefficientandlengthisP(z)P(0)exp(az)(1)aintheformulaisbendlosscoefficient,andintheformula,2sin2c/2,Vsinc,W22c12exp(4RV2W3)Ae3(2)aWR8PWV22W,istheradiusofopticalfibercore,Risbendradius,introduceaparameterV222neff/2ns/,whenthec1,undertheconditionoflargemodefield,useopticalfiberbendingradiusRisgreaterthanopticalfibercoreradius,formula(2)canbewrittenas223a1AeF122RV(3)86Pns6nsF(x)x1/2exp(x)(4)intheformula,nsisrefractiveindexofSiO2,Aeiscoefficientofelectricfieldinthepacketlayer,Pispowerofbasemembrane,isdistanceofmesoporesinthepacketlayer.Intype(3),V/Aincreaseswithairfillingratio(d/A),andF(x)isamonotonedecreasingfunction.Itturnsoutthatbendlossdecreaseswiththefillingratio,andincreasewithbendingradius.Therefore,wecandrawtheconclusion:inthecaseofinevitablebending,wecanoffsetopticalfiberbendinglossviaimprovingairfillingratios,thebendingresistabilityofPCFwillbestrongerwiththeincreaseofopticalfiberfillingratio.Itisrecommendedthatthelightspotofreferencelightandmeasurementlightonthesampleshouldbeconsistent,sothatreferencelightcanplayaroleofreference.Therefore,theopticalfibersensingprobeadopttheconcentriccirclesstructure,twopathsforlaunchingopticalfiberbundleworkasinnercirclewiththeuniformdistributionrandompermutation,theouterringworksasthereceivingfiberbundle.Inthecaseofenoughquantityofmeasurementopticalfiberandreferenceopticalfiber,thespotareaproducedbyexposuringtotheobjectwithtwowavelengthsoflight.Inactualproductionprocessmeasurementandreferencefiberbundleareused4000eachopticalfiberglassstrand.Asaresult,itcanapproximatethoughtthatmeasuringlightandreferencelightarethesamelightpath,thestructureisshowninfigure3.Accordingtospectrumanalysistheory,thelightof635nmwavelengthcannotbeabsorbedbyeffectivelight-absorbingsubstanceintheblood,itonlyrelatedtootherlight-absorbingfactors.Soitcanbeusedasreferencewavelength.Thelightin700nmwavelengthisnotonlyassociatedwithlightsuctionmaterialconcentration,butalsoassociatedwithotherlight-absorbingfactorsexpectthismaterial’sinfluence.Therefore,thelightemittedbyemittingdiodeD1andD2withthesameintensityandtwoseparatewavelengths,635nmand700nm,importintoopticalfiber,respectivelyafterreflectionbytheD3,andthengettheirintensitywhichcanreflectsthelevelofthebloodglucoseconcentrationthroughthespectralcomponentsandfiltertoisolatedifferentwavelengthsoflight.Thiskindofopticalfiberprobethatisarrangedcloselywiththesamefibersizeandopticalpathiseasytomakeribbon.Itcanautomaticallycompensatelightsourceintensityandreflectivityandtheinfluenceofenvironmentalfactorssuchaschangesonthemeasurementaccuracy.Figure3.Cross-sectionoffiberprobeHAREWAREDESIGNA.SystemdesignMonitoringdeviceconsistsofCPU,threeprobefiberbundlesensor,amplifiedcircuit,LCD,keyboard,typeYsplitter,alarmparts,filter,etc.,asshowninfigure4.Itsworkingprocessis:theprogramstoredinCPUwillcontroltheLEDdrivercircuittoproducea10kHzreferencewavelengthandameasurementwavelengthbyCPU’sIOport.Measuringlightandreferencelightirradiateonthebloodsamplethroughthethreeprobeopticalfiberbundlesensors.AndthereflectivelightimportYtypecoupler.Afterpassingfilter,twobeamsoflightatdifferentwavelengthswillrespectivelygointothelogarithmicamplificationanddifferentialamplification,andtheninputtotheCPUtoachieveA/Dconversionanddataanalysis,finallyreturntheresultontheLCD.KeyboardLightsource1logarithmicamplificationCPUPCFLightsensorsLEDsource2filterlogarithmicamplificationdifferentialamplificationFigure4.StructuredevicePhotoelectricconvertingandamplifyingcircuitdesignAccordingtotheoreticalanalysis,it’snecessarytoturnthebloodglucoseconcentrationmeasurementintolightintensityratiomeasurement.Afterphotoelectricconversion,itturnstomeasurecurrentratio.Therefore,toobtainthecurrentrationeedsthelogarithmicamplifieranddifferentialamplification.LOG114amplifierfromTIwhichhastworoad2independentofdifferentialamplifierandainternalreferencevoltageof2.5Vcanmeettheneedsofthetesting.Itisdedicatedtohedetectionofthephotodiodesignalopticalfibercableoutput.Thereisnoneedothercircuits.Italsosupportstodetect8ordersofmagnitude.Thedynamicrangeis100pA~10mA.Ithashighspeed,highaccuracyetc.advantages.Itisverysuitableforlightcontrolsystem,thereby,itcanavoidquadraticerrorbroughtbythecomposedofdiscreteelementinthecircuit.SOFTWAREDESIGNSoftwarestructureismainlycomposedofmainprogramandinterruptfunctionsanddisplayprogrammodulesandprogramflowisshowninfigure5.StartInitializeEndofRAM,LEDsampling?NYKeypress?Stoppulse,YdataanalysisGeneratepulseEnableValueoverflow?interruptionYInterrupt?NAlarmNYReadandDisplaysavedataresultsFigure5.ProgramflowIV.EXPERIMENTALRESULTSWeusethissystemtocollectthebloodsamplesafterlunchanddinner,thesamplingdataareshowninTable1.Afterdatafitting,wewillmakecomparisonbetweenfittingcurveandcurvemeasuredbybloodgiucosemonitoringsystem,asshownonFigure6.Table1.SampleddatabetweenlunchanddinnerBloodBloodglucoseOutputglucoseOutputconcentrationconcentrationVoltageVoltage(mgdL1)(mgdL1)821.39261182.7575931.832612202.85051012.18121323.15791092.51321383.34461152.65371403.39863.53V/e2.5gatloVtuptu2O1.519010011012013014080BloodGlucoseConcentration/mg*dL-1Figure6.ExperimentalresultsCKNOWLEDGMENTIwouldliketothankparticularlymylabcolleaguesfortheiradvicethroughoutthisresearch,andmymasterforhishelpwithsomemathematicalaspectsandopticalaspectsofthispaper.EFERENCESJ.C.Campo,M.A.PCrez,M.Gonzalez,F.J.FerreroDpto.deIngenicriaElkctricayElectronica,An“OptrodeTypeSensortoMeasureDissolvedOxygeninWater”inInstrumentationandMeasurementTechnology,Vol.III,pp.1537-1540,May,1999[2]WolfbeisO.S.“Fiberopticschemicalsensorsandbiosensors”I&11.CRCPress.BocaRaton,Florida1991JinehaeK，MoonDS，EomJB，etal，Microbendinginducedlossofaphotoniccrystalfiber,SPIETrans.pp.191-198,2003Drexler,P.BrnoUniv.ofTechnol.,BrnoJirku,T.;Steinbauer,M.;Fiala,P.Opticalmethodsforextremelevelmeasurement.inWaveformDiversityandDesignConference,2007.pp.131-135