Morrin, Aoife

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Smart Polymers in Microfluidics for Lab-On-A-Chip ApplicationsAoife Morrin12Micro-fluidicsConducting Polymers3Electrochemistry…..To Solve Healthcare ChallengesSo….How Do We Build ‘Em? Enabling Microfluidic Platforms Smart Materials Integration– And detection mechanism Tailor for Application– Urea detection in serum– Ammonia detection in breath– Glucose detection in saliva– Cholesterol detection in whole blood5Direct Incorporation of Electrochemistry into MicrofluidicsA.C. Power, B. White, A .Morrin, Electrochimica Acta , 2013,  DOI:10.1016/j.electacta.2013.04.091Conducting polymers on-chipPotentialCurrent702040608010001234550100150200Polymer Height (µ m)Electrode length (mm)Cross section of Electrode (µm)PANI electrochemical growth behaviour in channelsPeak current - closed channel (µµ µµA)2040Peak current - open channel (µµ µµA) 1000150020002500Thin layer flow cell polymerisationBatch cell polymerisation8Channel depth (µm) Average PANI thickness (µm) after 50 polymerisation cycles 35 7.53 ± 0.2460 27.70 ± 6.58110 49.93 ± 1.53180 80.53 ± 6.84No. of polymerisation cycles0 10 20 30 40 50Peak current - closed channel (0Peak current - open channel (0500 By creating inverse opal conducting polymer monolithic materials through sacrificial CC templates within channel High surface area monolithic structures for predictable flow profiles, electrochemically responsive chromatography, drug delivery, flow through sensors on chip, etcCan We Template These Materials On-Chip? 9Colloidal Crystal Formation On-Chip1) Capillary flow of PS suspension into channel2) Pinning of PS suspension to walls of the channel - evaporation flux, je3) Receding of meniscus line with continuous colloidal crystal growth – particle flux, jp and water flux, jw13LS2 LS6LS2 LS6Optimised CC Structures In MicrochannelsUnimodalGorey et al. (2013) Fabrication of a 3-dimensionally ordered binarycolloidal crystal within a confined channel. Submitted to Chem.Mater.PANI Inverse Opal Monoliths On-Chip – Electrochemical Synthesis+ EappTolueneYX12B. Gorey,  J. Galineau, B. White, M.R. Smyth,  A. Morrin, Electroanalysis 2012, 24,  1318 - 1323+ EappToluene13SOFT MATERIAL – WILL NOT WITHSTAND HIGH PRESSURESDecreasing current density as it grows away from electrode surfacePANI Monoliths On-Chip - Chemical PolymerisationClosed channel – flow through APS + H2SO4PS14Core-shell flow-through bed comprised electroactive PANIpolymerisationOpen channel – batch polymerisationOvercomes self-limiting nature of electrochemical polymerisationOvercomes gradient issues of electrochemical polymerisationOvercomes structural integrity issues….to a point….. In-situ polymerisation of styrene in the presence of a thermal initiator, a cross-linker, DVB and porogen, dodecanolFlush capillary with aniline, acid and oxidantFrom Beads…to Monolithic PS supports151 coating PANI 2 coatings PANI 3 coatings PANICharacterisation of PANI-coated polymer monoliths16Switchable PANI-coated PS-co-DVB monolithDecrease pH4854904955005055105155205250 10 20 30 40 50 60 70Distance along capillary (mm)Detector response (mV)(i)(b)(a)750850950105011501250135014500 10 20 30 40 50 60 70Distance along capillary (mm)Detector response (mV)(ii)(b)(a)(c)Blank MonolithDedoped PANI CoatingBlank MonolithDoped PANI CoatingConducting Polymers as Stationary Phases – particulate packingsReduced OxidisedCaffeine TheophyllineChriswanto & Wallace, J. Liq. Chrom. & Rel Technol., 19:2457 (1996) 17CaffeineTheophilineConducting Polymers as Stationary Phases - MonolithsCurrent challenge is to use electrochemistry to switch polymer state-Drug delivery- Stimuli-responsive Absorbance (mAU)1 mM Iodide on deprotonated PANI capillarychromatography0 5 10 15 20Absorbance (mAU)Retention time (minutes)1 mM Iodide on protonated PANI capillaryBlank on protonated PANI capillaryProcessable “Smart” polymers19Decrease pHDry Wetted StateZ' (Ohm)0 2000 4000 6000 8000 10000 12000 14000 16000- Z'' (Ohm)010000200003000040000water1 mM glucose3 mM glucose4 mM glucose6 mM glucose10 mM glucoseIncreasing time in glucoseInkjet printed PANI nanoparticles for ammonia gas and ammonium ionsNHN NHNHn NHN N NH Emeraldine SaltDeprotonatedby NH3+ (NH3)n- (H+)n+••• ••••PANI nanoparticles inkjet printed onto silver interdigitated (IDE) designIDEs fabricated by screen printingnEmeraldine BaseEarly days...(circa early 2007) Sensors inkjet printed using commercial printers Epson C42/C46 Cartridges emptied and refilled with nanoPANI formulation Unreliable, contact methodEpson C46And now….Dimatix Materials Printer 2831Inkjet Printing OverviewMany parameters affect quality:– Piezo potential (16 V default)– Pitch (dot spacing) typically 10 – 50 µm Too low – discontinuous films Too high – beading.– Nozzle temp (ambient to 70°C)A) Film optimisationExample of substrate/ink mismatch. Hydrophilic ink (PANI-PMAS) on hydrophobic surface (PET) leads to discontinuous  reduce viscosity– Stage temp (ambient to 60°C) faster drying times– Many others… Applied waveform Fluid rheology, substrate surface energy....Original OptimisedERROR: syntaxerrorOFFENDING COMMAND: --nostringval--STACK:69 13102 2 

Smart polymers in microfluidics for lab-on-a-chip applications

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Smart polymers in microfluidics for lab-on-a-chip applications

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