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WCPC Annual Technical Conference and Exhibition

11th Annual Technical Conference

Monday 09th - Tuesday 10th November 2015

Swansea Marriott Hotel,
Swansea, SA1 3SS

Keynote speaker: Stan Farnsworth of NovaCentrix

Stan Farnsworth is VP of Marketing at NovaCentrix and has been with the company since its inception in 1999. He is also currently serving as an elected advisory board member of the OE-A, the leading international association for printed and large-area flexible electronics, in the capacity as Vice Chair North America.

The conference is an opportunity to view the latest WCPC research in printing technology, to discuss the findings with researchers and to network with like-minded industrial delegates. Each presentation will be a technical paper based on latest results and analysis derived from controlled experiments and numerical models. All attendees will receive printed abstracts for each of the papers presented. Delegates will also have the opportunity to network at the conference dinner and should you wish the chance to arrange future visits to the WCPC facilities at Swansea University's Bay Campus.

WCPC is a world renowned research centre dedicated to advancing the understanding and productivity of all aspects of printing and coating. WCPC enhances the understanding of the printing and coating processes, exploits novel manufacturing using printing and applies its scientific findings to the benefit of its global industrial partners. With extensive experience in packaging and graphics printing the WCPC has built on this knowledge and become a centre for functional materials, plastic electronics and bio printing.

The conference will be held at the Swansea Marriott Hotel, Swansea, SA1 3SS. The venue has ample parking. Book the group rate for the conference accommodation here. To book accommodation at the conference rate either side of the 8th or 9th delegates should call + 44 (0) 1792 642020 quoting B82. The hotel conference rate is only available until 13th Septemeber 2015. This year's conference dinner will be dinner will be held at the National Waterfront Museum, Swansea.

The conference fee is £450 + VAT. APN and icmPrint members will have one complimentary delegate seat and will be entitled to a discounted rate for any other delegates that are registered and paid via the member company. (The discounted rate will be £300 + VAT per additional delegate).

The delegate registration fee covers conference attendance, lunches, refreshments and conference dinner. (No accommodation is included in the fee and the booking of the accommodation is the responsibility of the delegate).

If you would like to promote your service or product to delegates, table top exhibitor space will be available in the refreshment and lunch area. Each exhibitor will be allocated an area to take a table top & roll up display. As space is limited, we would advise potential exhibitors to make a booking as early as possible. The cost of exhibiting is £250 + VAT in addition to the delegate fee of £450 + VAT.

Conference Agenda

Monday 09th November

09:00 Registration & Coffee
09:30 - 09:45 Welcome,
David Gethin, Welsh Centre for Printing and Coating
09:45 - 10:30 Keynote Presentation: Is There a Role for Aesthetics in Printed Electronics Applications?,
Stan Farnsworth, Novacentrix
10:30 - 11:00 Innovation in Large Area Electronics,
Philip Cooper, EPSRC CIMLAE
11:00 - 11:30 Networking Break
11:30 - 12:00 Measurement of surface and interface instabilities under extensional flows,
Alex Holder, Welsh Centre for Printing and Coating
12:00 - 12:30 Investigation of Effect of Poly Ethylene Glycol as a Plasticizer for the Manufacture of Nanocellulose Films ,
Zari Tehrani, Welsh Centre for Printing and Coating
12:30 - 13:00 Modifying Flexographic Plate Surface Energy using UV-Ozone Treatment,
David Beynon, Welsh Centre for Printing and Coating
13:00 - 14:00 Lunch
14:00 - 14:30 Extensional Flow and Properties of Polymer Solutions for Printing,
Miles Morgan, Welsh Centre for Printing and Coating
14:30 - 15:00 The Effect of Changes in Ink Rheology on the Ability to Print Fine Conductive Lines,
James Claypole, Welsh Centre for Printing and Coating
15:00 - 15:30 Networking Break
15:30 - 16:00 Advancing the Production of OLED's by Controlling Ultra-thin Deposition through Flexographic Printing,
Ben Mogg, Welsh Centre for Printing and Coating
16:00 - 16:10 Mechanical Properties of Pre-coated Metal Systems, Specifically Stress Whitening,
Emily Radley, Welsh Centre for Printing and Coating
16:10 - 16:40 3-D Printing High Performance Structural Materials with Integrated Electronics for Dynamic Component Engineering,
Daniel Thomas, Welsh Centre for Printing and Coating
16:40 - 17:10 Printed Conductive Grids,
David Shaw, Welsh Centre for Printing and Coating
17:10 Round up of the day and close
19:45 Conference Dinner at The Waterfront Museum

Tuesday 10th November

09:30 - 09:45 Start of Second Day,
David Gethin, Welsh Centre for Printing and Coating
09:45 - 10:15 Formulation and Deposition of Intermediate Layers on Rough Steel Substrates for Large Area Solar Cells,
Tatyana Korochkina, Welsh Centre for Printing and Coating
10:15 - 10:45 Characterisation of Ink Transfer from Open and Closed Anilox Rolls,
Sakulrat Foulston, Welsh Centre for Printing and Coating
10:45 - 11:15 Rapid Prototyping Technique for Fabricating Conductive Tracks on Transparent Conductors,
John Lau, Welsh Centre for Printing and Coating
11:15 - 11:45 Networking Break
11:45 - 12:15 The Effects of Mesh Ruling and Particle Size for EL Phosphors,
Matt Everett, Welsh Centre for Printing and Coating
12:15 - 12:45 Ink Transfer in Flexo Printing of Glass,
Sakulrat Foulston, Welsh Centre for Printing and Coating
12:45 - 13:15 Fabrication of Electronic Contacts using Aerosol Jet Deposition,
Chris Phillips, Welsh Centre for Printing and Coating
13:15 - 14:15 Lunch
14:15 - 14:45 FLEXIPOWER: Development of a Printed Wireless Energy Harvesting System,
Tim Mortensen, Welsh Centre for Printing and Coating
14:45 - 15:15 Novel Pressure Sensor Utilising Direct Contact Between two Piezoresistive Layers,
Youmna Mouhamad, Welsh Centre for Printing and Coating
15:15 Round up and Close

"Is There a Role for Aesthetics in Printed Electronics Applications?"

Stan Farnsworth - Novacentrix

The technology community tends to think of printed and flexible electronics in terms of performance metrics like conductivity, transparency, and adhesion. While these are certainly important for the product engineers utilizing these technologies, rarely does a final customer consider these factors. This talk will show how aesthetics can and do play a role in the successful adoption of printed and flexible electronics technologies, with examples in the automotive and wearables markets.

"Innovation in Large Area Electronics"

Phillip Cooper - EPSRC CIMLAE

The concept of using manufacturing processes such as printing to deposit functional materials directly onto flexible substrates to make electronic devices and intelligent systems is revolutionary from both cost and environmental perspectives. Such manufacturing plants could be built with one tenth to one hundredth of the capital cost of conventional semiconductor or thin-film fabrication plants. Devices made from these sources can be produced in high-volume over large areas on flexible substrates thereby enabling electronic systems to be deployed in a wide variety of non-traditional situations such as on paper and plastic, on clothes, in furniture, cars and buildings, as well as on packaging and even in and on the human body. The EPSRC Centre for Innovative Manufacturing in Large Area Electronics, co-ordinates cutting edge projects with centres of academic excellence in the UK aiming to provide viable production solutions in Large Area Electronics. This presentation studies some of these projects and shows how they aim ultimately to provide end to end system solutions for industrial adoption.

"Measurement of Surface and Interface Instabilities Under Extensional Flows"

Alex Holder, Davide Deganello, Alex Lubansky and Rhodri Williams

Keywords: Rheology, Interfaces, Surface Instabilities

The technology community tends to think of printed and flexible electronics in terms of performance metrics like conductivity, transparency, and adhesion. While these are certainly important for the product engineers utilizing these technologies, rarely does a final customer consider these factors. This talk will show how aesthetics can and do play a role in the successful adoption of printed and flexible electronics technologies, with examples in the automotive and wearables markets.Liquid-liquid interfaces have special physical properties that have drawn the attention of scientists for hundreds of years. These unique boundaries are critical in industrial print processes such as offset lithography. Oil-water interfaces also play a primary role in membrane formation, the production of nanomedicines and the creation of functional nanoparticles.

Currently, the flow of immiscible liquids is typically modelled on the fundamental principles of surface tension and viscous forces however, little is known about how these forces might change within an interface under flow and the precise mechanisms that dominate flow behaviour. Liquid bridges and capillary thinning of those bridges are often used to elucidate extensional flows found on the large scale.

In the work presented, a new methodology has been developed for direct measurement of interfacial resistances under tension in the normal direction. Two immiscible liquids were placed between two discs such that an interface existed between them and stretched to form an unstable liquid bridge. The liquid bridge break up containing an interface was found to take longer than either constituent liquids under the same experimental conditions. Further, an apparent resistance of the interface under break up was determined.

Understanding this break-up and forces will have a primary importance for improving the application of printing for functional applications. This research is carried out as part of EPSRC grant reference EP/M008827/1.

"Investigation of Effect of Poly Ethylene Glycol as a Plasticizer for the Manufacture of Nanocellulose Films"

Zari Tehrani, Henriette Rogstad Nordli, Gary Chinga-Carrasco, Brita Pukstad, Tim Claypole and David T. Gethin

There is potential that nanocellulose can act as a substrate for biomedical applications in which printing can expand its use as a functionalized biomaterial. Nanocellulose has a variety of advantages in biomedical devices that including wound dressings. The material is transparent, does not promote bacterial growth and provides a moist wound-healing environment. Because it is intrinsically brittle, research is needed to develop its flexibility and strength. Therefore, in this work, the effect of plasticizers such as Glycerol and PEG 400 was explored in conjunction with TEMPO mediated oxidation.

Scanning electron microscopy and laser profilometry were used to measure film morphology together with UV-vis spectroscopy. The mechanical strength of the films was also measured. This led to film formulation containing Glycerol or PEG at 10 to 40% by weight, where the PEG modification demonstrated wound dressing properties and suitability for surface modification by printing. Importantly, cytotoxicity tests were performed using Normal Human Dermal Fibroblasts and Human Epidermal Keratinoytes. Preliminary results showed no effect in the metabolic activity when fibroblasts was incubated in the presence of PEG-films, whereas a reduction was measured in keratinocytes. No significant cell death was detected in any of the cell-types.

The PEG-modified films were demonstrated to be capable of receiving a nanocellulose bioink that was used to modify the film using different volume printing techniques notably screen, flexography and gravure. This demonstrates the potential of these materials is to make flexible and translucent films that can be effectively modified by printing processes for the manufacturing of wound dressings.

"Modifying Flexographic Plate Surface Energy using UV-Ozone Treatment"

Tamara Tomaĉegović, David Beynon, Tim Claypole, Sanja Mahović Poljaček

In all flexographic printing applications the surface energy of the printing plates is critical for effective ink transfer in combination with the surface tension of the printing inks. The surface free energy of the plate is determined by the chemical make-up of the surface of the plate material. This is determined during photopolymer plate making at the point of UVA or UVC post exposure. UV-ozone treatment is usually used for surface decontamination however in this work it has been used to rapidly introduce permanent changes to the surface free energy of the polymer by increasing the number of oxygen containing bonds in the surface chemistry. This chemical change affected the polar component of surface free energy however changes to the surface topography were also observed that affected the measured dispersive component of surface energy. The changes in surface free energy are dependent upon exposure duration, the polar component continues to increase with exposure time however the dispersive component reaches a peak at 1.5min exposure. Exposure was not extended beyond 5min as this produced visible signs of degradation to the plates.

Printing trials were conducted on an IGT printability tester and a commercial press with different plate materials and different durations of UV/ozone exposure. The resulting prints were analysed for quality parameters including track width, tonal element dot size and optical density, with improvements in track spreading and tone gain measured. The method of modifying photopolymer plate surface free energy using UV-ozone treatment was shown to be fast and effective with benefits found in the printed product. The ability to modify the plate surface free energy will be of increased importance for optimal printing of functional materials as the surface tension of the ink is often dominated by the functional material with little opportunity for modification.

"Extensional Flow and Properties of Polymer Solutions for Printing"

Miles Morgan, Alex Holder, Davide Deganello

Keywords: Extensional Rheology, Ink Characterisation, CaBER

Printing techniques can impart large stresses on printing inks across a range of strain rates. Characterising the rheology of printing inks is therefore of considerable importance, particularly with printed electronics, for which print uniformity is crucial. While the shear rheology of such inks is commonly investigated, their extensional rheology is less so, despite the presence of significant extensional flows in many printing processes including flexographic and inkjet printing. It is therefore desirable to realise a convenient method to characterise the extensional behaviour of inks.

This work utilises the technique of capillary break-up extensional rheometry (CaBER) to characterise the uniaxial extensional rheology of printable polymer solutions in relation to their shear rheology. In this technique, a small volume of sample fluid is loaded between two plates to form a cylindrical liquid bridge. The fluid is then subjected to a step strain resulting in the formation of a liquid filament that collapses due to its surface tension. The evolution of the filament radius with time, recorded via high-speed camera, can be used to extract information pertaining to the extensional rheology of the fluid.

Presently, water-based polymer solutions - namely polyvinyl alcohol (PVA) of various molecular weights, concentrations and degrees of hydrolysis - have been assessed in addition to Newtonian silicone oils to validate an in-house CaBER's accuracy and operability limits. Such tests for the latter Newtonian fluids found constant viscosities in reasonable agreement with expected values. Similarly, low molecular weight (LMW) PVA was effectively Newtonian, while solutions containing high molecular weight (HMW) and more hydrolysed polymer exhibited strain hardening, elastic properties.

This work therefore finds CaBER a useful means of assessing fluid behaviour under monitored extensional flows. With the identification of extensionally differing inks of similar shear rheology, subsequent study can look to link this behaviour to print uniformity and functionality.

"The Effect of Changes in Ink Rheology on the Ability to Print Fine Conductive Lines"

James Claypole

Inks are a fundamental part of the printing process, and being able to fully understand how they behave is critical for the reproduction of fine conductive features. To characterise the inks, a series of rheological experiments was performed. These included viscometry, small amplitude oscillatory shear (SAOS) and more complex rheological methods such as controlled stress parallel superposition (CSPS). To tie these rheological parameters, for a set of conductive inks, to the printing performance a metric was defined. The metric chosen was the smallest reproducible line width that could be achieved by screen printing using a constant set of printing settings. The results showed that there was a good correlation between the printing results and the advanced rheological methods.

"Advancing the Production of OLED's - Controlling Ultra-Thin Deposition Through Flexographic Printing"

Ben Mogg

Methods of fabricating and controlling Organic Light Emitting Diode (OLED) layers effectively are paramount for achieving a functional and durable device. The deposited film needs to be uniform and homogenous to avoid inconsistencies in the OLED luminescence. Although methods of depositing the ultra-thin sub 100nm layers within OLED are effective, they are relatively slow and expensive. This presentation therefore demonstrates flexography as an alternative method for depositing the semiconductor layer for OLED onto glass substrate. In this case a proprietary semiconducting polymer dispersed in xylene was used. This material functions as the hole injecting layer. The low polymer concentration and requirement for aromatic solvent presented challenges for the process; conventional photopolymer printing plates degraded rapidly on contact with xylene and rubber printing plates were found to be sufficiently resilient. Through optimisation of printing parameters and surface modification of both the printing plate and substrate with UV ozone exposure, a consistent sub 100 nm film was achieved. Flexographic printing will enable a substantial reduction in layer fabrication time, as well as allowing roll to roll mass production at lower cost.

"3-D Printing High Performance Structural Materials with Integrated Electronics for Dynamic Component Engineering"

Daniel Thomas, Chris Phillips, Ben Clifford and Tim Claypole

During this project, research has been undertaken to develop the 3-D fabrication of innovative structural components with integrated electronic components. This work has harnessed the initial 3-D deposition of materials, including; concrete, high strength nylon polymer and carbon fibre to form agile structural elements. By further 3-D printing conductive polymer and aerosol-jet electrical connections onto these structures, this has allowed for the integration of electronic components. It has been shown that multi-material and multilayer assembly structures can be printed to produce complex architectures. These have facilitated the detection of; strain, temperature, distortion, load and damage within a component. This novel means of engineering functional solid-state components combines structure of high performance materials with inbuilt sensors as a scalable and viable future technology.

"Printed Conductive Grids"

David Shaw

Keywords: Inkjet, Feature Size, Distribution

The global flat glass industry, forecast to be worth $100 billion in 2016, is still a substantial growth sector with a wide range of products available on the market, within a variety of sectors. As with many established technologies there is a constant quest to identify the next market-changing product or niche market area. An area of particular interest is that of functionalised glass, which includes conductive glass used for applications such as solar cell electrodes, automotive glass used for anti-fogging screens and resistive heating windscreens and architectural glass used for toughened/structural glass, low-E glass and fire safety glass. All of these bring additional benefits via the use of coating technology, traditionally applied via CVD which is integrated with the glass production process or PVD high vacuum processes.

In the interests of improving the functionality of these pre-existing products, or adding functionality to new products, the additive nature of printing is seen as an excellent target point for investigating this avenue. Digital printing techniques would seem to offer an excellent option for this due to the fine feature sizes and rapid turnaround capabilities of these techniques. This would fit in with the requirements of improving the pre-existing products as it allows the capability to deposit fine conductive tracks with a minimal visible 'footprint'.

Various nano materials have been deposited via inkjet printing, for the creation of conducting grids. These deposits are intended to enhance the electrical properties of the various substrates utilised, whilst minimising any optical issues. The resulting samples have also been subjected to a range of analysis techniques to examine parameters such as the feature sizes, optical transmission, resistance and durability of the resulting samples.

"Formulation and Deposition of Intermediate Layers on Rough Steel Substrates for Large Area Solar Cells"

Tatyana Korochkina, Mari-Fe Menendez, Luis Andrés, Pascal Sanchez, Tim Claypole and David Gethin

Keywords: Building Integrated Photovoltaics, printing, coating, steel substrates, intermediate layer

One of the most promising renewable energy technologies is photovoltaics (PV). Building Integrated Photovoltaics (BIPV) systems often have lower overall costs than PV systems requiring separate, dedicated, mounting systems. There is a growing interest in BIPVs manufactured by roll-to-roll (R2R) processes. Printing and coating offer promising manufacturing methods, where both flexible and semi-rigid devices can be manufactured using low-cost, high-throughput processes. Relatively “rough”, low cost structural steels are among attractive metals as they meet PV substrate requirements in terms of barrier to oxygen and water. However, their roughness needs to be reduced significantly to make them compatible with thin-film solar cells (TFSC) such as chalcopyrite (CIGS), amorphous silicon (a-Si:H) or organic (OPV). Although, this can be achieved using mechanical and electrochemical techniques, the post treatment makes the steel substrate very expensive. A cost effective alternative solution is an introduction of intermediate layer(s) (IL) compatible with R2R processes between the steel substrate and TFSC. In addition to reduction in roughness of the steel surface to avoid shunts during TFSC manufacturing, the IL can prevent diffusion of chemical elements (e.g. Cr, Ni) from the steel surface and provide electrical insulation between the steel substrate and the TFSC back contact electrode to enable development of TFSC modules by serial cell interconnection. Recent publications on IL deposition on steel substrates reported several drawbacks including poor adhesion, lack of electrical insulation, high annealing temperature, etc.

In this study, a SiOx intermediate layer was created by combining a non-vacuum sol-gel technique developed at ITMA with lab-scale printing and coating techniques developed at WCPC. The SiOx based IL was deposited on non-treated steels such as AISI430 stainless steel, and DX51D bare cold rolled low carbon steel as well as DX51D hot-dip galvanized with Zn or Al which was cold rolled to achieve the desired final thickness. Several batches of sol-gel were prepared for life time tests and printing trials. Results of extensive characterisation of sol-gel solutions and ILs printed onto four steel substrates are reported. We have successfully demonstrated that the SiOx sol-gels have great potential as continuous, defect free insulating IL for development of BIPV systems based on TFSC.

"Characterisation of Ink Transfer from Open and Closed Anilox Cells"

Sakulrat Foulston, David Beynon, Davide Deganello, David Gethin, and Tim Claypole

Keywords: Characterisation, Ink transfer, Open Cell

Flexographic printing is continually improving in quality with a goal being similar quality characteristics to gravure printing. Improvements in print quality can be achieved through developing the key components of flexography, namely anilox rolls, printing plates and inks. The anilox roll is the primary means of controlling the amount of ink transferred to the printing plate and in this investigation, closed and open cell engraved geometries were studied to understand their ink transfer characteristics. Three commercial anilox rolls were used for this investigation; a standard closed cell anilox roll (1,000LPI screen count and ink volume average of 2.80cc/m2) and two open "slalom" channel anilox rolls Band-S (948LPI with 3.62cc/m2) and Band-XS (1,074LPI with 2.31cc/m2). Samples were printed on a full scale commercial press with the open and closed cell anilox used to print in each of the four CMYK print units. Samples were collected for direct comparison of closed and open cell anilox performance for standard and HD (High Definition) plating (offers high resolution imaging of up to 4,000 pixel per inch) and ink technologies. The ink transfer performance of the different anilox technologies have been measured using optical density and microscopy image analysis measurements to determine print density, dot area and ink spreading.

"Rapid Prototyping Technique for Fabricating Conductive Tracks on Transparent Conductors"

John Lau

Printed electronic devices such as electroluminescent displays, organic light emitting diodes and photovoltaic devices, all require transparent, electronically conductive materials for their electrodes. In situations where flexible devices are desired, transparent electrodes produced from Indium doped Tin Oxide (ITO) coated polymer films have been a popular choice. Due to material scarcity, cost and the desire for greater device performance, alternatives to ITO could prove beneficial. One approach is to produce a composite electrode combining highly transparent, moderately conductive coatings with a fine printed grid of opaque, highly conductive metallic ink. Composite electrodes provide a great opportunity to tune the optical and electronic performance of the resulting electrode for specific applications.

The optical effect of composite electrodes is problematic in certain applications. The optical quality of the printed products is determined by scattering/diffracting properties of the printed tracks. In some circumstances, the interaction between printed tracks and light is critical in direct light as it will dramatically affect the optical performance of the printed product. In this study we used an innovative rapid prototyping technique to produce patterns that could potentially be used for improving the optical performance of the printed tracks. Additionally a sintering technique for conductive inks is also being investigated.

"The Effects of Mesh Ruling and Particle Size for EL Phosphors"

Matt Everett, Tim Claypole

Keywords: Screen Thickness, Particle size

A method of creating Electroluminescent (EL) devices is to layer them using screen printing methods. Of crucial importance when constructing the device is the separation and isolation of the two plates and thus the creation of the electric field between them. The two main factors determining plate separation are the thickness of the phosphor layer and the thickness of the dielectric layer.

Previous work has investigated the effect of screen printing press parameters on layer thickness. Following on from this, further work looked at the effect of mesh ruling on the printed layers, using screens with theoretical ink volumes ranging from 53cm3/m2 to 9.6cm3/m2. Layer thickness was measured using white light interferometry and optical microscope as appropriate. As well as investigating layer thickness, a complete print free from pin holes was also desired as this would create a short circuit in the device causing catastrophic failure. The phosphor particles had an average diameter of 25µm which presents an uneven topography for the dielectric layer to overcome. The ability of the various layer thicknesses to overcome this is discussed in the presentation.

"Ink Transfer in Flexographic Printing of Glass"

Sakulrat Foulston, David Beynon, Davide Deganello, David Gethin, and Tim Claypole

Keywords: Ink Transfer, Glass Substrate, Flexography

Decorated and functional glass is widely used in the construction industry. Screen printing is the main method in the production process; however the screen printing process has limitations on production speed, print resolution and ink film thickness, also screen size is fixed independent of the print area. This adds cost to the production that could be reduced by using flexographic printing with the additional benefit of printing finer detail of graphics and the potential to offer new functionalities. A study has been carried out to gain understanding of ink transfer and flexographic print quality on glass using different anilox cell engraved geometries for printing on glass substrates. Six bands of anilox cell engraved geometries were used for this investigation. Five bands were closed cells with screen counts ranging from 68 to 1,179LPI and a corresponding ink volume range of 49.80 to 2.22cc/m2. One band was open cell with screen count of 356LPI and ink volume of 4.60cc/m2. The same printing plate of 145LPI and same Black UV flexo ink were used for all anilox bands. The main parameters used to determine the performance of ink transfer and print quality were ink optical density, dot area and dot gain.

"Fabrication of Electrical Contacts using Aerosol Jet Printing"

Chris Phillips, Ben Clifford

Keywords: Aerosol jet, Electronics, Nano silver

Aerosol jet deposition offers numerous advantages over conventional processes for printed electronics, namely higher resolution, better registration capabilities and the ability to print onto small components and uneven surface. This presentation will describe the use of aerosol jet to deposit conductive and insulating materials in fine detail for electronics applications. The effect of deposition and curing parameters on feature dimensions and performance will be described as well as considerations for scale-up.

"FLEXIPOWER: Development of a Printed Wireless Energy Harvesting System"

Tim Mortensen

With the push towards ubiquitous low power internet of things (IoT) devices the use of batteries as a power source will result in an increasing number of logistical and physical issues. For small form-factor sensors the additional bulk of the battery and the impracticality of recharging or replacing depleted batteries can outweigh their potential benefits.

Energy harvesting can be used to power devices and wireless energy harvesting is of increasing interest in the world of printed electronics for powering low energy devices from nearby radio frequency (RF) sources. These sources can be dedicated transmitters or ambient RF signals such as mobile phone signals or WiFi.

FLEXIPOWER, an EPSRC funded project is developing an entirely printed energy harvesting system suitable for high volume manufacture, as part of the CIMLAE group. Such a system will become increasingly important as the capabilities of other printed electronics allows for the creation of more complex printed devices. The project aims to produce a high frequency (up to 2.4GHz) rectification stage, along with tuned antenna and voltage management circuitry to provide power to a range of devices. This talk details a number of design considerations and use cases for such a system and describes the various techniques used in the creation of the components.

"Novel Pressure Sensor Utilising Direct Contact between Two Piezoresistive Layers"

Youmna Mouhamad

We report a novel piezoresitive ink obtained by dispersing functionalised graphene nanoplatelets in a polymer matrix and subsequently used in a pressure sensor. The high lateral resistance of the functionalised ink simplifies the architecture of the sensor, and subsequent fabrication, as a separating gap is not needed. A sensor is obtained by bringing into contact two Indium Tin Oxide (ITO) substrates on which the piezoresistive ink is printed. These thin and flexible sensors are sensitive and can be used for forces up to 2000 N. The piezoresistive response can be tuned by changing the number of layers piezoresitive ink printed. The morphologies of the printed layers can also be correlated to the sensor response. The various applications of this ink are also discussed in the presentation.

"Mechanical Properties of Pre-coated Metal Systems, Specifically Stress Whitening"

Emily Radley

The project is an investigation of stress whitening in paint as part of a pre-coated metal (PCM) system. The PCM is used for forming applications and stresses in the process are responsible for the whitening. Stress whitening is the development of micro-cracks or voids on the paint coating surface. The cracks are within the nanometre scale range and this causes visible light to be diffracted causing cracks to appear white rather than the pigment colour or colourless (in the case of un-pigmented coatings). Resolutions to be investigated include the addition of nano-particulates to the paint solution as well as higher temperature forming. Various forms of microscopy, including SEM, will be used to evaluate the severity of stress whitening with and without these process modifications.

Stan Farnsworth - Novacentrix

Stan Farnsworth is VP of Marketing at NovaCentrix and has been with the company since its inception in 1999. Since 2008 he has been responsible for strategic and tactical marketing for all NovaCentrix products, including the company's award-winning PulseForge photonic curing tools and Metalon conductive inks. Previously, Stan was at Applied Materials where he led engineering teams in product development and manufacturing operations. He has a mechanical engineering degree from Rice University and a master's degree in heat transfer and fluid mechanics from the University of Texas. He is also currently serving as an elected advisory board member of the OE-A, the leading international association for printed and large-area flexible electronics, in the capacity as Vice Chair North America.

Phillip Cooper - EPSRC CIMLAE

Philip Cooper joined the EPSRC Centre for Innovative Manufacturing in Large Area Electronics in February 2015 after retiring from De La Rue International following 14 years service in Research. Philip has worked in various research and commercial roles for over 40 years in many diverse industries and has wide experience in designing innovative products for mass production. He has degrees in Physics and Electrical Engineering from London University, a PhD in Transducer Design from Exeter University and is a Fellow of the Institute of Physics. While at De La Rue, Philip had a number of senior roles from Technology Applications Manager to the Head of Research developing security product ideas for the next decade. Prior to De La Rue, Philip championed innovation in his roles in electrical machines, magnetic metals, automotive, textiles and defence. At Exeter University he helped innovate, design and instigate manufacture of a Tactile Aid for the profoundly deaf.

Philip has been a major supporter for Printed Electronics and has presented seminal work on printed electronics at many major conferences and is widely published in the field.

Alex Holder - WCPC

Alex joined the Welsh Centre of Printing and Coating in August 2014 after completing his PhD in Nanotechnology at Swansea University. As a PhD student, he worked on validating advanced rheometric techniques such as Optimal Fourier Rheometry (OFR) and controlled stress parallel superposition (CSPS) while working closely with Procter and Gamble on how these techniques might provide better data for their flow models. Since joining the WCPC, Alex has been involved in the development of printed pressure sensors before moving on to his current project. Today, Alex seeks to utilise skills gained in his PhD and develop advanced rheometric techniques specifically tailored to illuminate technical and scientific problems within the printing industry; primarily to better understand interfacial flows and surface instabilities.

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Zari Tehrani - WCPC

Zari is a researcher at WCPC and has been working as a post-doctorate researcher at Swansea University since 2011. Her PhD was on the Functionalisation of Semiconductor Surfaces for Biosensor Applications. In 2013 she joined the WCPC focusing on the development and application of printed electronics techniques for energy harvesting and storage through photovoltaic technology. Recently she has started working on Bio-compatible cellulose nanostructures for advanced wound healing applications by printing techniques.

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David Beynon - WCPC

David is a Research Officer based in the Welsh Centre for Printing and Coating. Having completed a PhD researching ink transfer mechanisms in flexographic printing David's research interests have grow to include graphics, electronic and functional printed materials. Recent projects have included printed functional devises including electromagnetics, sensors and rheological characterisation of functional inks working in collaboration with academic and industrial partners. David currently works on the Centre for Innovative Manufacture in Large Area Electronics (CIMLAE) project formulating functional inks for the ARPLAE and Flexipower projects.

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Miles Morgan - WCPC

Miles is currently studying for a PhD in Nanotechnology at the Welsh Centre for Printing and Coating (WCPC) in Swansea University. He has a bachelor's degree in physics and completed a Master's degree in nanotechnology at Swansea University in 2014, during which he worked at the WCPC to enhance transparent conducting films containing carbon nanomaterials. Presently, Miles' work concerns the development of rheometric techniques for ink characterisation with particular interest in extensional flow and surface instabilities.

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James Claypole - WCPC

James graduated from Cardiff University with a degree in Civil Engineering. He has recently finished his PhD at Swansea University in advanced rheology of printable materials. He worked as an intern at the Welsh Centre for Printing and Coating during his undergraduate study and is now working as a post-doctoral research assistant at Swansea University working on advanced rheology and its impact on the ability to print electronics funded as part of the EPSRC Centre of Innovative of Large Area Electronics based in WCPC.

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Ben Mogg - WCPC

Ben is a final year PhD student at WCPC and has been working on a collaborative project between the WCPC and CDT (Cambridge Display Technology Ltd) on controlling film formation and drying for printed polymer OLED devices with emphasis on roll-to-roll processing. Ben obtained his first degree in Aerospace Engineering in 2012.

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Dr Daniel Thomas - WCPC

Daniel is a senior research officer at the Welsh Centre for Printing and Coating, currently exploring the application of three-dimensional printing processes for producing novel integrated devices. Currently he is an Editor of the Journal of Optics and Laser Technology covering; light detection and ranging, laser material interactions, optical fibres and new laser development themes and he is also a deputy Editor of the Journal of Failure Analysis and Prevention covering metal failure analysis and corrosion fatigue themes. He has previously worked in the research and development of industrial high power lasers, in which this work has been applied to process new steel grades used in the manufacture of heavy construction equipment. Daniel's multidisciplinary research activities include the areas of; precision optics, laser materials processing, additive materials manufacturing and three-dimensional biocompatible material deposition. Being a science writer for the past five years he has written many hundreds of articles for numerous popular science and technology websites, magazines and science columns, on subjects diverse as new manufacturing processes, 3D-Printing, engineering sustainability, laser technology and nanomaterials.

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Dr Tatyana Korochkina - WCPC

Tatyana obtained a degree in Mechanical Engineering from University of Voronezh, Russia in 1978. She worked for the Metal-Polymer Research Institute of Belarus Academy of Sciences from 1978 to 1999, while also completing her PhD. Since 1999, Taytana has been a senior researcher in the Welsh Centre for Printing and Coating. Her areas of expertise include both numerical modelling and experimental investigation in all aspects of the process for different applications including sensors and energy harvesting.

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Sakulrat Foulston - WCPC

Sakulrat started working as a system engineering assistant graduation with a Bachelor's degree in chemical engineering from Mahidol University in Thailand. She then joined an alkaline manufacturer and worked for over 5 years as a marketing executive. After moving to Swansea, she resumed her studies in 2008, gaining an MSc in financial management prior to an MRes qualification in environmental management. Currently, studying engineering doctorate at WCPC in ink transfer in the flexographic process after receiving a scholarship under MATTER (Manufacturing Advances Through Training Engineering Researchers) scheme.

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John Lau - WCPC

Yin Cheung Lau (John) received the MEng degree in Chemical Engineering from Swansea University in 2013. He as previously interned with Bayer MaterialScience and Haemair Ltd. He is currently pursuing the EngD degree in Materials Engineering at Swansea University and his current research interest is the fabrication of conductive patterns on flexible substrates.

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Matt Everett - WCPC

Matt is a third year postgraduate EngD at Swansea University, sponsored by EPSRC and DST Innovations. Matt has also produced work for the WCPC during his undergraduate study and graduated in 2013 with a Masters of Mechanical Engineering, first class honours after also completing a year in industry with Britten-Norman Aircraft on the Isle of Wight.

Matt is researching Electroluminescent (EL) technology for his EngD project, working closely with DST Innovations in Bridgend, South Wales. The project looks at ink and substrate properties as well as ultimately the best method of manufacture for EL red, green, blue displays. He is currently using screen printing as a manufacture method for the displays as the process lends itself well to the layers used in EL technology.

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Dr Chris Phillips - WCPC

Chris is a senior researcher at The Welsh Centre for Printing and Coating in Swansea. He has worked extensively with companies in printing and related industries with trouble-shooting, product development and environmental compliance either through commercially funded consultancy or European grants. As well as conventional printing, he has focused on clinical applications including printing biological materials and lung disease diagnosis through chemical analysis of breath. His current work is focussed on conductive ink development.

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Tim Mortensen - WCPC

Tim obtained an MPhys degree from Swansea University in 2009 and completed his EPSRC funded PhD on the "Manipulation of the magnetron orbits of particles and clouds in a two stage buffer gas accumulator" at the same institution in 2013. During his research with antimatter systems at Swansea and later in Saclay, Paris, he not only gathered and analysed experimental data, but designed and built a range of bespoke hardware and software solutions to facilitate simplified data acquisition and analysis. Upon his return to the UK in mid-2014, Tim was offered a role on a project in the field of printed electronics at the Welsh Centre for Printing and Coating (WCPC) to create a low cost printed pressure sensor. The project far exceeded its expectations. The technology behind the sensor has been patented and is in the process of being commercialised by industrial partners of the University. He now works on the FLEXIPOWER project, an EPSRC Centre for Innovative Manufacturing in Large Area Electronics funded project developing printed wireless energy harvesting systems.

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David Shaw - WCPC

David is a currently undertaking his EngD at Swansea University in association with SPECIFIC, the WCPC and NSG.

He has previously attended Cardiff University where he attained a BSc degree in Physics, before attending Swansea University and gaining a Masters of Research degree in Materials Engineering. For his masters research he worked in partnership with Tata Steel, performing research in the area of corrosion science; with a particular focus on the corrosion dynamics and characteristics of tin coated steel in a range of acidic environments. His current research involves working with various academic and industrial partners, looking to add further functionality to glass substrates and developing analysis techniques for the outputs of the project.

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Youmna Mouhamad - WCPC

Youmna has a Bachelor's degree in physics and chemistry from the University of Aix-Marseille II. Having been awarded an Erasmus grant she spent the final year of her degree in the University of Leeds. After this she continued her studies in Leeds University, obtaining a Master of Physics. She then joined the polymer physics group in Sheffield University obtaining a PhD studying the dynamics and phase separation of spin coated films. With the aim of combining her interest in applied research and knowledge in polymer physics she joined the Welsh Centre for Printing and Coating as a research assistant. Her main focus is the development of functionalised inks for various applications.

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