Morrin, Aoife

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Inkjet Printing as a Tool for the Fabrication of Conducting Polymer-Based Sensors & BiosensorsDr. Aoife MorrinThe National Centre for Sensor Research1National Centre for Sensor ResearchSchool of Chemical SciencesDublin City UniversityIrelandOverview1. Introduction2. Inkjet printing of conducting polymer3. High specification, flexible, inkjet printed gas sensor platformThe National Centre for Sensor Research24. Biosensor fabrication & applicationOverview1. Introduction2. Inkjet printing of conducting polymer3. High specification, flexible, inkjet printed gas sensor platformThe National Centre for Sensor Research34. Biosensor fabrication & applicationIntroduction• Advances in materials and engineering are paving the way for new and more capable sensors• Most recent advances are not originating from new transduction materials, but more from materials and innovations that reduce overall cost and improve qualityThe National Centre for Sensor Research4• ‘Enabling technologies’ are principle drivers in sensor fabrication developmentPrinted Sensors• Mass market application areas• High demand for low-cost, mass-producible sensor products in specific key markets such as point-of-care medical diagnostics and smart packaging, remote environmental sensing, etc….• Early 1980s saw the enormous commercial success of the screen-printed glucose biosensorThe National Centre for Sensor Research5• 9 billion glucose tests performed annually• Inkjet printing – set to surpass screen-printing???  • Today we have more sophisticated materials available…Enabling Technology: Inkjet Printing….• Rapid, reproducible, cheap way to manufacture sensors• Easily scaled up, suited to large and small production volumes• Quality control in real time• High precision, claiming a resolution of ~ 25 µm• Thin film deposition (nm). Thinner films can yield faster response times• Amenable to simultaneous deposition of more than one material – multi-component layers, microarrays•The National Centre for Sensor Research6Sensor optimisation through combinatorial printing• Non-contact printing (substrate and print head don’t touch), suitable for fragile substrate e.g., membranes• Aqueous solution are printable – important for biological species• Low wastage, important for precious materials• Flexible design process• ………..…..Combined With Processable, High Quality Sensing Materials….The National Centre for Sensor Research7Interesting Functional Materials for Sensing Include:Electroactive/Optically active materialsConducting PolymersMetallic InksBiomolecules for BiosensingMembranes….Overview1. Introduction2. Inkjet printing of polyaniline3. High specification, flexible, inkjet printed gas sensor platformThe National Centre for Sensor Research84. Biosensor fabrication & application• Suitable for chemical sensingof acids and bases through its excellent doping/dedoping capabilites • Desirable material for Sensor Platforms Based on PolyanilineNH2Aniline MonomerThe National Centre for Sensor Research9biosensing because of its good redox properties and hence can act as a diffusionless mediator for electron transfer between enzyme centres and the electrode transducerDoped Polyaniline (conductive state)• Developing various electrochemical sensor/biosensor platforms using polyaniline-based polymers• Examining various sensor fabrication approaches such as • electrochemical deposition• nano-templating • printing approachesPANI-based Sensor ResearchThe National Centre for Sensor Research10• Printing methods permit processability, low cost and disposability• Aiming to demonstrate that inkjet printing, combined with the right materials is a feasible, valid approach to sensor fabricationBack In The Old Days….• Glassy Carbon Electrode Platform• Traditional 3-electrode cell setup to electropolymerise PANI films to electrode surfaceAuxiliary ElectrodeWorking ElectrodeReference ElectrodeN2 inSupporting electrolyte (with analyte)Potentiostat (for control and analysis of response)The National Centre for Sensor Research11• Works really well, but laborious fabrication procedure • How to translate into a commercially relevant product??Potential (V)-0.4-0.20.00.20.40.60.81.0Current (µA)-100-50050Screen-Printing for Electrode FabricationThe National Centre for Sensor Research12l Low start up and manufacturing costl Mass productionl Disposabilityl Platform for glucose biosensor industry3 cm1 cmInkjet Printing of Silver for Electrode FabricationSilver Inter-Digitated Array (IDA) Single ElectrodeThe National Centre for Sensor Research13• Commercial Ag product• ~ 1 Ω cm-1 (1 layer)• Challenge will be to print inert carbon electrode layers comparable to screen-printed carbon• Can print gold or platinum as alternativesModifcation of Electrode: Processable PANIThe National Centre for Sensor Research14• New, processible materials • Water-soluble, or stable nanodispersions• High processibility• Aqueous-based• Good redox activity and conductivityPANI Nanodispersion Characterisation01020301 10 100 1000 10000Diameter (nm)Volume (%)< 100 nm diameterThe National Centre for Sensor Research15No Stabiliser Present* DBSA Stabiliser Present*Jiaxing Huang, Richard B. Kaner, A gew. Chem. Int. Ed. 2004, 43, 5817-5821Inkjet Printing of PANIMulti-Head Desktop Epson Inkjet Printer Commercial Research Fuji Dimatix PrinterThe National Centre for Sensor Research16Inkjet Printed PANI Electrodes• PANI nanodispersions inkjet printed onto IDAs for gas sensor platform• Also printed to carbon paste working electrodesThe National Centre for Sensor Research17Resulting ‘Smooth’ Morphology(a) Bare SPE (b) 10 PrintsThe National Centre for Sensor Research18(c) 20 Prints (d) 30 PrintsMorphology1 print1 cm40 prints1 cm10 prints1 cm4000The National Centre for Sensor Research19Elimination of classic drop-coated ‘coffee-ring effect’No. of Prints of PANI1 5 10 20 30 40Film Thickness (nm)0100020003000Overview1. Introduction2. Inkjet printing of conducting polymer-based sensor3. High specification, flexible, inkjet printed The National Centre for Sensor Research20gas sensor platform4. Biosensor Fabrication & applicationAmmonia Sensing• Ammonia is a highly toxic chemical species• Classified as a major pollutant • The ammonia sensing industry spans a wide range of markets• Mature market, lacking in innovation• Niche for low-cost portable sensors e.g., for health & safety The National Centre for Sensor Research21Detection Mechanism – Gas Sensing• Conductimetric mode– 2 electrode cell• Ammonia deprotonates PANI backbone– Emeraldine salt (ES) to emeraldine base (EB) form– Decrease in NHN NHNHn NHN N NH Emeraldine SaltDeprotonatedby NH3+ (NH3)n- (H+)n+••• ••••The National Centre for Sensor Research22conductivity• Apply potential to IDA– current flows through PANI film– Vapp : step or ramp• Measure change in current on NH3 exposurenEmeraldine BaseVappImeasVappImeasPANI (ES) PANI (EB)+ NH3- NH3Increasing Print Layers – Increasing Current • Sequential inkjet printed layers– Quasi-linear increase from 1 – 10 layers– Begins to plateau µ A 400500600µ AThe National Centre for Sensor Research23above 10 layers (inset)– Thicker layers do not seriously effect response/recovery times – porous filmNo. of PANI layers0 2 4 6 8 10Sampled current / 0100200300y = 60.4 x - 67.2r ² = 0.9939200x1500 IDAn = 3No. of Layers0 5 10 15 20 25Sampled current / Normalised sampled current0.60.81.0 T50T90Sensor Response Times• Response times for PANI IDA (n=4)– t50 ~ 15 s– t100 < 60 s• ~ 60 ppm NH3Exposed to NH3 vapourThe National Centre for Sensor Research24Time / s0 15 30 45 60 75 90 105 120 135 150 165 180Normalised sampled current0.00.20.4 • Response times currently within those specified by ISA (Instrument Society of America)– t50 < 90sFlexible Heater Substrate• MincoTM thermofoil heaters• Thin and flexible– fast temperature equilibration• up to 200°C– sub 100°C used for PANI sensors• Compatible with inkjet printingThe National Centre for Sensor Research25• Possibility of printing directly to heater substrateInkjet printed PANISilver IDA on PET substrateFlexible heating foilNormalised current0.60.81.0 Non-heated50 C60 C70 C80 CResponse Behaviour Using Flexible Heater SystemThe National Centre for Sensor Research26Time / s0 500 1000 1500 2000 2500 3000 3500Normalised current0.00.20.4 Increasing temperature reduces sensitivity to increase linearity over relevant rangeSensor Recovery Using Flexible Heater SystemNormalised current0.60.81.0Time / s0 500 1000 15001.0• Room Temp recovery > hours• 80°C recovery < secondsThe National Centre for Sensor Research27Time / s-100 0 100 200 300 400Normalised current0.00.20.4Normalised current-2.0-1.5-1.0-0.50.00.5log (ln(I0 - I))0.350.400.450.50[NH3] / ppm0 20 40 60 80 100Current / µA0.00.20.40.60.81.01.21.41.61.8r ² = 0.9971Quantitative AnalysisPANI IDA sensor is far The National Centre for Sensor Research28[NH3] / ppm2 4 6 8 20 40 60 801 10 1000.200.250.30superior when compared with a commercial sensor– Honeywell NH3 sensor– Zellweger Impulse XP– 1 - 100 ppm rangeExtension to Inkjet Printed Gas Sensor Array• Recently received ‘Proof of Concept’ Funding to build an inkjet printed gas sensor array• Gases including H2S, CO, Cl2 and NO2 • Exploit inkjet printing to fabricate arrays of The National Centre for Sensor Research29polymer (polyaniline?) layers modified to be selective towards specific gasesOverview1. Introduction2. Inkjet printing of conducting polymer-based sensor3. High specification, flexible, inkjet printed gas The National Centre for Sensor Research30sensor platform4. Biosensor fabrication & applicationBiosensorSignal ProcessorTarget AnalyteInduces Physical or Chemical The National Centre for Sensor Research31TransducerBiomolecule Digital SignalMatrixChangeInkjet Printed Biosensor Publications> 13,000 hits for ‘biosensor’ on Web of Science> 500 Peer-Reviewed Publications on ‘screen-printed and biosensor’ Just 10 Peer-Reviewed Publications on ‘inkjet and biosensor’!!!The National Centre for Sensor Research32Field: Publication YearRecordCount% of 10 Bar Chart2002 1 10.0000 %2004 4 40.0000 %2005 3 30.0000 %2006 1 10.0000 %2006 1 10.0000 %Thermally Printed Biosensor• Horseradish Peroxidase (HRP) and Glucose Oxidase (GOD)-based biosensors• Thermal printing does not affect the activity of the enzymes• PEDOT/PSS electronic communication with enzyme (but employed a soluble mediator to enhance this)The National Centre for Sensor Research33Setti et al. (2007). Sens. Actuat. (126) 252Inkjet Printed Cantilever Array ChipsThe National Centre for Sensor Research34• Highly controlled deposition of inkjet printed functional layers •Demonstrated prototype as a DNA biosensor and a gas sensor array• Inkjet printing can, uniquely functionalise cantilevers individually very easily• Fast, easy to assemble, scalableBietsch et al. (2004). Nanotechnology (15) 873Characterisation of hydrophilic and hydrophobic inkjet printed SAMs8 inkjet printed polymers on individual cantileversScreen-Printed Carbon Paste ElectrodeThe National Centre for Sensor Research35Scan Rate Study Current (mA)0.00.51.01.5Electrochemistry of Inkjet Printed PolyanilineRelationship of peak current with scan rateR2 = 0.9679-1.00E-030.00E+001.00E-032.00E-030 100 200 300 400 500peak Current (A)peak anodic currentsThe National Centre for Sensor Research36Potential (V)0.20.40.60.81.0Current (mA)-1.5-1.0-0.5 500 mV 300 mV 200 mV 50 mV 25 mV R2 = 0.9584-2.00E-03scan rate (mV.s-1)peak cathodic currentsRelationship of peak current with (scan rate)1/2-2.00E-03-1.00E-030.00E+001.00E-032.00E-030 5 10 15 20 25(scan rate)1/2 \ (mV.s-1)1/2peak current \A peak anodic currentspeak cathodic currents

Inkjet printing as a tool for the fabrication of conducting polymer-based sensors & biosensors

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Inkjet printing as a tool for the fabrication of conducting polymer-based sensors & biosensors

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