UtilizespacetechnologiesforuseinamedicalorhealthapplicationonearthBackgroundOhmatexdevelopsphysiologicalandenvironmentalsensorsforinclusioninmedicaldevices,sportswear,andprotectiveclothing.Wedevelop,testandvalidatesensors,workingwithmedicalexperts,physiologistsandtheEuropeanSpaceAgency(ESA)totest,trialandvalidateourproducts.Integratingsensorsintotextileisveryvaluableforcontinuousandprolongedmonitoring,assensorscanbeintegratedintosocks,t-shirts,trousersorworkwear.Thismakesitdiscreet,non-obtrusiveandeasytomount.Since2009,wehavebeenonacontractwithESAforthedevelopmentandadvancementofapairofmusclemonitoringexercisetightsthatmeasuresastronauts’muscularactivityandfluidshiftsduringlongerdurationsinspace.Innear-zerogravityconditions,musclesdeterioratequicklyunlesstheyareexercisedintensively.Thisisaseriousissueforastronautswhospendatleast2hoursworkingouteverydaywhilstinspace.Inordertooptimizetheastronaut’sexerciseprogramme,andultimatelyreducemuscledegeneration,Ohmatexisdevelopingatechnologywhichmeasurestheeffectoftheastronauts’trainingexercisesinspace,andmonitorstheimpactofweightlessnessonthebody.Togainadeeperinsightintomuscularactivityandfluidshiftsthreegarmentintegratedsensortechnologiesiscombined:EMGsensorswhichdetectmuscleactivation;NIRSsensorswhichdetectchangesinoxygenatedhemoglobinanddeoxygenatedhemoglobincontentinselectedmusclegroupsandStrainGaugePlethysmographysensorswhichmeasurelimbcircumferenceasanindicationofchangesinmusclevolume.Thecombineddatawillthenbeusedtoanalyzemuscleactivityandoptimizetrainingandcountermeasures.

Thestudywillalsogeneratenewknowledgeaboutfluidshiftsinthelegs,makingthetechnologyofinterestincasesofheartandkidneyfailureandpreeclampsia.

NotonlyisthisanexcitingdevelopmentforOhmatex,butitalsoopensupcommercialspin-offopportunitiesintelemedicineandhealthmonitoring,wheresmarttextilesaregaininggroundbyleapsandbounds.ThechallengeInwhichmedicalorhealthapplicationcanoneofthetextileintegratedsensorsoracombinationofthesensorsbeutilizedwithvaluablebenefitsforpatientsand/orhealthpractitionersandhow?DetailsaboutthesensorsPlethysmographyTheplethysmographysensorisatextilesensor.Itdetectschangesinthestretchoftheofthesensorsandthus,canbeusedtomeasurechangesinlengthandcircumference.Intheastronauttights,theplethysmographysensorsareusedtoestimatevolumechangesofthelegbymeasuringthecircumferenceattwopointsandthencalculatingthevolumebasedondifferentassumptions.EMGEMGsensorsdetectstheelectricpotentialgeneratedbymusclescells.Whenmoremusclesfibersarerecruitedtoeithersustainaconstantloadortomeetanincreaseinload,theamplitudeoftheEMGsignalincreases.InthetopgraphofFigure1theamplitudeoftheEMGsignalincreaseswithincreasingload.Thedataiscollectedforanathleteperforminganincrementexercisewithincreasingloaduntilfailure.ThebottomgraphofFigure1BplotsthefrequencyoftheEMGsignalduringtheexercise.Thefrequencyisdecreasingwithincreasingloadduetomusclefatigue.

Figure1.EMGdatafromanathleteperforminganincrementexercisewithincreasingloaduntilfailure.Inthetopgraph,theamplitudeoftheEMGsignalincreasedwithincreasingloadduetoincreasingmusclefiberrecruitment.Inthebottomgraph,thefrequencyoftheEMGsignalisdecreasingwithincreasingloadduetoincreasingfatigueofthemuscle.

EMGhasbeenstudiedinawidevarietyofcontextsandsituationstogainknowledgeaboute.g.load,strain,gait,andtechnique.CriteriaThetextileelectrodes(leftpicture,Figure3)mustbetightlyconnectedtotheskinabovethemuscleofinterest.Apairoftrainingtightsisadequatetoobtainagoodskinelectrodecontact,eliminatingmovementartefactsandtoavoiddisplacementoftheelectrodes.

NIRSNIRSisatoolforassessingtheoxygenationstatusandhemodynamicsinthemusclesaswellasotherorgansbycalculatingthechangesinoxygenatedanddeoxygenatedhemoglobinandtherebyalsothechangesinbloodflowinthetissue(thesumofoxygenatedanddeoxygenatedhemoglobinisameasureoftotalbloodvolumeofthetissue).NIRScanhowever,notdistinguishiftheoxygenconcentrationiscarriedbymyoglobinorhemoglobin.Duringexercise,thebloodflowtothemusclesincreasesduetoincreaseddemandforoxygeninthemuscle.Themusclesabilitytoutilizethisoxygenisdependentonseveralfactors.However,NIRSisamethodtomonitortheavailabilityofbloodandoxygeninthemuscle,aswellasthemusclesabilitytoutilizethisoxygen.InthemiddleandbottomgraphofFigure2,therateofboththeratioofoxygenatedhemoglobin(middlegraph)aswellasthebloodflow(bottomgraph)ischangingastheloadisincreasing.Thisclearlyillustratedthestatusofthemusclesandtheirabilitytoperformtheexerciseatthedifferentloads.Heartrate(topgraph)increaseslinearlywithincreasingload,whichdoesnotprovideinformationabouttheabilitytosustainload,contrarytothemuscleoxygenationandbloodflowdata.

Figure2.HeartrateandNIRSdatafromanathleteperforminganincrementexercisewithincreasingloaduntilfailure.Inthetopgraph,heartrateisincreasinglinearwithincreasingload.Inthemiddlegraph,theratioofoxygenatedhemoglobinisdecreasingwithincreasingrateastheloadisincreased.Likewise,therateofwhichbloodflowisincreasingisalsochangingbyincreasingload(bottomgraph).

CriteriaTheNIRSprobe(Figure3)mustbefirmlyconnectedtotheskinabovethemuscleofinteresttoavoidmovementartefactsanddisplacementoftheprobe.Additionally,itisimportanttoeliminatetheexternallightaroundtheprobeasmuchaspossibleasthiswillotherwiseinterferewiththesignalandreducethequalityofthedata.

Figure3.EMGandNIRSintegratedintoexercisetightsandsocks.LeftpictureshowstheEMGtextileelectrodesontheleftandtheNIRSprobeontheright.Middlepictureandrightpictureshowstheintegrationfromtheoutsideofapairofexercisetightsandsocks.