Inkjet Printing as a Tool for the Inkjet Printing as a Tool for the Fabrication of Conducting Polymer Fabrication of Conducting Polymer- Based Sensors & Biosensors Based Sensors & Biosensors Dr. Aoife Morrin National Centre for Sensor Research School of Chemical Sciences Dublin City University Ireland The National Centre for Sensor Research The National Centre for Sensor Research 1
Overview Overview 1. Introduction 2. Inkjet printing of conducting polymer 3. High specification, flexible, inkjet printed 3. gas sensor platform 4. Biosensor fabrication & application The National Centre for Sensor Research The National Centre for Sensor Research 2
Overview Overview 1. Introduction 2. Inkjet printing of conducting polymer 3. High specification, flexible, inkjet printed 3. gas sensor platform 4. Biosensor fabrication & application The National Centre for Sensor Research The National Centre for Sensor Research 3
Introduction Introduction • 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 quality • ‘Enabling technologies’ are principle drivers in sensor fabrication development The National Centre for Sensor Research The National Centre for Sensor Research 4
Printed Sensors Printed 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 biosensor • 9 billion glucose tests performed annually • Inkjet printing – set to surpass screen-printing??? • Today we have more sophisticated materials available… The National Centre for Sensor Research The National Centre for Sensor Research 5
Enabling Technology: Inkjet Enabling Technology: Inkjet Printing…. 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 • Sensor 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 • ……….. The National Centre for Sensor Research The National Centre for Sensor Research 6
…..Combined With Processable, …..Combined With Processable, High Quality Sensing Materials…. High Quality Sensing Materials…. Interesting Functional Materials for Sensing Include: Electroactive/Optically active materials Conducting Polymers Metallic Inks Biomolecules for Biosensing Membranes …. The National Centre for Sensor Research The National Centre for Sensor Research 7
Overview Overview 1. Introduction 2. Inkjet printing of polyaniline 3. High specification, flexible, inkjet printed 3. gas sensor platform 4. Biosensor fabrication & application The National Centre for Sensor Research The National Centre for Sensor Research 8
Sensor Platforms Based on Sensor Platforms Based on Polyaniline Polyaniline • Suitable for chemical sensing of acids and bases through its Aniline NH 2 excellent doping/dedoping Monomer capabilites • Desirable material for • Desirable material for biosensing because of its good redox properties and hence can act as a diffusionless mediator for electron transfer between Doped Polyaniline enzyme centres and the (conductive state) electrode transducer The National Centre for Sensor Research The National Centre for Sensor Research 9
PANI PANI- -based Sensor Research based Sensor Research • Developing various electrochemical sensor/biosensor platforms using polyaniline-based polymers • Examining various sensor fabrication approaches such as • electrochemical deposition • nano-templating • printing approaches • printing approaches • 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 fabrication The National Centre for Sensor Research The National Centre for Sensor Research 10
Back In The Old Days…. Back In The Old Days…. Potentiostat (for control and analysis of response) N 2 in • Glassy Carbon Electrode Platform Auxiliary Electrode Working Electrode Reference Electrode • Traditional 3-electrode cell setup to Supporting electrolyte (with analyte) electropolymerise PANI films to electrode surface • Works really well, but laborious fabrication procedure 50 Current ( µ A) 0 • How to translate into a commercially relevant -50 -100 product?? 1.0 0.8 0.6 0.4 0.2 0.0 -0.2 -0.4 Potential (V) The National Centre for Sensor Research The National Centre for Sensor Research 11
Screen Screen-Printing for Electrode Printing for Electrode Fabrication Fabrication ● Low start up and manufacturing cost ● Mass production ● Disposability ● Platform for glucose biosensor 3 cm industry The National Centre for Sensor Research The National Centre for Sensor Research 1 cm 12
Inkjet Printing of Silver for Inkjet Printing of Silver for Electrode Fabrication Electrode Fabrication Silver Inter-Digitated Array (IDA) Single Electrode • Commercial Ag product • ~ 1 � cm -1 (1 layer) • Challenge will be to print inert carbon electrode layers comparable to screen-printed carbon • Can print gold or platinum as alternatives The National Centre for Sensor Research The National Centre for Sensor Research 13
Modifcation of Electrode: Modifcation of Electrode: Processable PANI Processable PANI • New, processible materials • Water-soluble, or stable nanodispersions • High processibility • Aqueous-based • Good redox activity and conductivity The National Centre for Sensor Research The National Centre for Sensor Research 14
PANI Nanodispersion PANI Nanodispersion Characterisation Characterisation 30 ) e (% < 100 nm diameter 20 Volum 10 0 1 10 100 1000 10000 Diameter (nm) No Stabiliser Present* DBSA Stabiliser Present *Jiaxing Huang, Richard B. Kaner, Angew. Chem. Int. Ed. 2004 , 43, 5817- The National Centre for Sensor Research The National Centre for Sensor Research 5821 15
Inkjet Printing of PANI Inkjet Printing of PANI Multi-Head Desktop Epson Commercial Research Fuji Inkjet Printer Dimatix Printer The National Centre for Sensor Research The National Centre for Sensor Research 16
Inkjet Printed PANI Electrodes Inkjet Printed PANI Electrodes • PANI nanodispersions inkjet printed onto IDAs for gas sensor platform • Also printed to carbon paste working electrodes The National Centre for Sensor Research The National Centre for Sensor Research 17
Resulting ‘Smooth’ Morphology Resulting ‘Smooth’ Morphology (a) Bare SPE (b) 10 Prints (c) 20 Prints (d) 30 Prints The National Centre for Sensor Research The National Centre for Sensor Research 18
Morphology Morphology 10 prints 1 print 40 prints 1 cm 1 cm 1 cm 1 cm 1 cm 4000 Film Thickness (nm) Elimination of classic drop-coated 3000 ‘coffee-ring effect’ 2000 1000 0 1 5 10 20 30 40 No. of Prints of PANI The National Centre for Sensor Research The National Centre for Sensor Research 19
Overview Overview 1. Introduction 2. Inkjet printing of conducting polymer-based sensor 3. High specification, flexible, inkjet printed 3. High specification, flexible, inkjet printed gas sensor platform 4. Biosensor Fabrication & application The National Centre for Sensor Research The National Centre for Sensor Research 20
Ammonia Sensing Ammonia 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 Research The National Centre for Sensor Research 21
Detection Mechanism Detection Mechanism – – Gas Sensing Gas Sensing • Conductimetric mode Emeraldine Salt – 2 electrode cell +• •• N N N N • Ammonia deprotonates H H H PANI backbone n – Emeraldine salt (ES) to Deprotonated + (NH 3 ) n by NH 3 - (H + ) n emeraldine base (EB) form •• •• N N N N – Decrease in – Decrease in H H H H n conductivity Emeraldine Base � � � � • Apply potential to IDA + NH 3 – current flows through PANI film - NH 3 ��������� ��������� – V app : step or ramp � ��� � ��� • Measure change in current � ���� � ���� on NH 3 exposure The National Centre for Sensor Research The National Centre for Sensor Research 22
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