NewGenerationofImplantMedicalDevices

BobPuersKULeuvenESAT-MICAS

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Mainenvisagedlongtermtargetapplications

• Neurology• Electro-corticography electrodeformation• Self-adaptingelectrodenetwork• Reconstructionofmissingbrainconnectivities

• Urology• Theurologicalpacemaker• Sensingthebladder:micro-movements,electricalactivity,pressure

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Neurology

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Toppost.co

Ourquest:thecomfortableimplant

§ Arrayswithresorbablematerials astemporarysupport• Strongenoughduringinsertion• Lowerirritationduringuse

§ Targetuseinlesioncavities• Designforhighmechanicalflexibility• Recordingandstimulationfortherapy

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GeneralAim

• Exploringnewneuralelectrodearrayconcepts• Verylongtermneuralinterfacing• Highresolutionneuralinterfacing

• Basedonflexibleelectronics,advancedpackagingand/orbiofunctionalisation

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Materialselection

• Non-resorbablesensormaterials:• Ptelectrodesandconnectors,PIorparyleneCinsulation• Classicalmaterials,butverythinandfinelypatterned

• Resorbablemateral:Chitosan• Itcanbedissolvedinanacidicenvironment,facilitatingspin-onprocessing

• Goodadhesion• Hashaemostatic andantisepticproperties• Canbeformedintoaporous,fastresorbable form• Degradationratecanbevariedbyalteringthedegreeofdeacetylation

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Fabrication

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Invivotesting

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§ Implantation on meninges ->or under meninges inrats

§ Measure physiological response

Typicalmeasurementofstimulusandphysiologicalresponse

Measure here

~ Stimulate here

Amplitudeofresponseovertime

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!

Whatisnext:Flexiblespiderstructures

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Ourcurrent implanttechnology

• Thin filmpolyimide (7µm)• Developed foruseinbrain lesion cavities• Improved insulation• Ptmetal,orIrox forreduced impedance

• Tested upto1year inrats• Tested ECM/chitosan coating• Recent :Mg/PLGA

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Underdevelopment

• Neutrotropic electrode arrays• Resorbable needle shaped electrode arrays• Highresolution interfacing electronics• Flexibleactivesilicon-based arrays

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NeurotrophicElectrode

• Goal:improvinglong-termreliabilityofintracorticalmicroelectrodes

• Hollowtubeelectrodefilledwithneurotrophicgrowthfactorcontaininghydrogel

• Reducedimmunologicalresponse(glialscarring)

• Guidedneuritesprouting(chemotacticgradientofgrowthfactors)

à nomicromotions/highSNR

à Improvedelectrodelifetime

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Partially resorbable electrode arrays

• Need relatively stiff needle-like structuretoget into thebrain forhigh resolution interfacing

• Carrierdissolves,only bare minimumstays behind• Minimizing chronic damage

• Maininspiration:• Turner• CharlesLieber

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Finalgoalforhigh-res neurointerfacing

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Polyimide electrodes

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• Currently:modest number ofelectrodes (±30),improvewith ASICtoward 1000+ofcorticalelectrodes

• Peripheral nerveelectrodes with magnesium stiffenerforinsertion

Urology

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mammothhospital.org

Evaluationofbladderfunction

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Urodynamicmeasurementsproviderelevantphysiologicalparameters:

Conventionalmethods:IntraluminalpressureFlow/volumemeasurementsCathetercystoscopyEMGsphinctermuscle

Analysis/diagnosistoolNonewinsights

Understandingthebladderfunction

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Contractile activity in the bladder

Micturition contraction

Central Nervous System:

- Inhibitory mechanisms

- Excitatory mechanisms

Autonomous activity

Localized contractions during

filling phase.“Pacemaker cells”

Non-micturition contractions

Urinary urgency?

BladderDetrusor

Sphyncter

Pelvic floor

Earlierresearchworkinourgroup

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- capacitivesensing- introducingflex- separatecircuit- inductivepowering

- linkingwithstimulator- towardstheultimateurologicpacemaker

Interestingphenomenaobserved

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AfullyimplantableMEMSsystem

• Multiplelocations:• “Star”shapeddevice• Wraparoundbladder

• Submucosalplacement• Protectionandfixation

• Bladderstretching(upto100%)• Flexiblesubstrate• Structuralstretchability

• Modulardevice:• Sensorsystem:onbladder• Power&communication:subcutaneous

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• Central node• 1 accelerometer• 1 abdominal reference

pressure sensor• 2 microcontrollers

• 3 distal end nodes• 1 accelerometer• 1 bladder pressure

sensor

AfullyimplantableMEMSsystem

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Conclusions

• Fullyimplantablesystemforbladdermonitoring• Proofofconceptonrats/pigcadaver• Testedandvalidatedinvitro• Dummyimplantedinvivo

• Biocompatiblepackaging• Allowsmeasuringpigvoidingbehaviorinawake,naturalstate• Autonomyuptoseveralweeks,dependingonusage

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Finally,whatisourmission?

• Researchtotakemostoutof:• Polymers• 3Dmicro-fabrication&interconnects

• Hybridassembly• Packagingmaterialsforimplants

• Flexible&Stretchable• Soft,jelly-likebehavior• Bioresorbable materials

• Focusonimplant-humaninterface• Lowpowerelectronics&communication

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AnneMarieCernoch’sartistimpression:“Electro-Gelly”

Acknowledments

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• FrederikCeyssens• LuigiBrancato• JohanCoosemans• BramLips• DriesKil• MarkoBakula• MichelDeCooman

• FWO,EC,IWT,ERC,KULeuven