̽��ֱ�� of Cambridge - printing

John Siberch: Cambridge’s first printer (and record debtor?)

zs332 — Wed, 17 Nov 2021 10:33:00 +0000

2021 is the 500th anniversary of the first works printed in Cambridge

Coffee stains inspire optimal printing technique for electronics

Anonymous — Wed, 12 Aug 2020 18:00:00 +0000

Have you ever spilled your coffee on your desk? You may then have observed one of the most puzzling phenomena of fluid mechanics – the coffee ring effect. This effect has hindered the industrial deployment of functional inks with graphene, 2D materials, and nanoparticles because it makes printed electronic devices behave irregularly.

Now, after studying this process for years, a team of researchers have created a new family of inks that overcomes this problem, enabling the fabrication of new electronics such as sensors, light detectors, batteries and solar cells.

Coffee rings form because the liquid evaporates quicker at the edges, causing an accumulation of solid particles that results in the characteristic dark ring. Inks behave like coffee – particles in the ink accumulate around the edges creating irregular shapes and uneven surfaces, especially when printing on hard surfaces like silicon wafers or plastics.

Researchers, led by Tawfique Hasan from the Cambridge Graphene Centre of the ̽��ֱ�� of Cambridge, with Colin Bain from the Department of Chemistry of Durham ̽��ֱ��, and Meng Zhang from School of Electronic and Information Engineering of Beihang ̽��ֱ��, studied the physics of ink droplets combining particle tracking in high-speed micro-photography, fluid mechanics, and different combinations of solvents.

Their solution: alcohol, specifically a mixture of isopropyl alcohol and 2-butanol. Using these, ink particles tend to distribute evenly across the droplet, generating shapes with uniform thickness and properties. Their results are reported in the journal Science Advances.

“ ̽��ֱ��natural form of ink droplets is spherical – however, because of their composition, our ink droplets adopt pancake shapes,” said Hasan.

While drying, the new ink droplets deform smoothly across the surface, spreading particles consistently. Using this universal formulation, manufacturers could adopt inkjet printing as a cheap, easy-to-access strategy for the fabrication of electronic devices and sensors. ̽��ֱ��new inks also avoid the use of polymers or surfactants – commercial additives used to tackle the coffee ring effect, but at the same time thwart the electronic properties of graphene and other 2D materials.

Most importantly, the new methodology enables reproducibility and scalability – researchers managed to print 4500 nearly identical devices on a silicon wafer and plastic substrate. In particular, they printed gas sensors and photodetectors, both displaying very little variations in performance. Previously, printing a few hundred such devices was considered a success, even if they showed uneven behaviour.

“Understanding this fundamental behaviour of ink droplets has allowed us to find this ideal solution for inkjet printing all kinds of two-dimensional crystals,” said first author Guohua Hu. “Our formulation can be easily scaled up to print new electronic devices on silicon wafers, or plastics, and even in spray painting and wearables, already matching or exceeding the manufacturability requirements for printed devices.”

Beyond graphene, the team has optimised over a dozen ink formulations containing different materials. Some of them are graphene two-dimensional ‘cousins’ such as black phosphorus and boron nitride, others are more complex structures like heterostructures – ‘sandwiches’ of different 2D materials – and nanostructured materials. Researchers say their ink formulations can also print pure nanoparticles and organic molecules.This variety of materials could boost the manufacturing of electronic and photonic devices, as well as more efficient catalysts, solar cells, batteries and functional coatings.

̽��ֱ��team expects to see industrial applications of this technology very soon. Their first proofs of concept – printed sensors and photodetectors – have shown promising results in terms of sensitivity and consistency, exceeding the usual industry requirements. This should attract investors interested in printed and flexible electronics.

“Our technology could speed up the adoption of inexpensive, low-power, ultra-connected sensors for the internet of things,” said Hasan. “ ̽��ֱ��dream of smart cities will come true.”

̽��ֱ��research was funded by the EPSRC, InnovateUK and the Royal Society.

Reference:
G. Hu et al. ‘A general ink formulation of 2D crystals for wafer-scale inkjet printing.’ Science Advances (2020). DOI: 10.1126/sciadv.aba5029.

Using an alcohol mixture, researchers modified how ink droplets dry, enabling cheap industrial-scale printing of electronic devices at unprecedented scales.

̽��ֱ��natural form of ink droplets is spherical – however, because of their composition, our ink droplets behave like pancakes

Tawfique Hasan

Drying droplets: the red arrows showing the end of the particle trajetories

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Yes

Scientists write ‘traps’ for light with tiny ink droplets

sc604 — Mon, 23 Oct 2017 23:13:56 +0000

̽��ֱ��printing-based approach, jointly developed by researchers at the ̽��ֱ�� of Cambridge and the Hitachi Cambridge Laboratory, combines high-resolution inkjet printing with nanophotonics – the study and harnessing of light on the scale of a billionth of a metre – the first time that this combination has been successfully demonstrated. ̽��ֱ��results are reported in the journal Advanced Materials.

Over the last decade, inkjet printing – the same basic technology that many of us have in our homes – has advanced to the point where it can be used to print very small devices, using a range of printable materials, including living cells, as ‘ink’. This approach is both simple and low-cost, and it is widely used in electronics and biotechnology.

“Most inkjet printers push the ink through the nozzle by heating or applying pressure, producing ink droplets about the size of the diameter of a human hair,” said the paper’s co-first author Dr Vincenzo Pecunia, a former PhD student and postdoctoral researcher, and now visiting researcher, at the ̽��ֱ��’s Cavendish Laboratory.

Pecunia’s research focuses on printable optoelectronic materials for a range of applications, and his group recently obtained a printer based on electrohydrodynamic jets: a long word that essentially means a printer capable of ultra-high resolution printing. Instead of relying on pressure or heat, this type of printer applies a voltage to the ink, providing enough force to push it through a much smaller nozzle, producing ultra-small ink droplets – ten to a hundred times smaller than those produced by conventional printers.

Thanks to a chance meeting between Pecunia and co-first author Dr Frederic Brossard from the Hitachi Cambridge Laboratory, the researchers found that the new printer could print structures small enough to be used in nanophotonics, which is Brossard’s area of research.

“Previous efforts to combine these two areas had bumped into the limitations of conventional inkjet printing technology, which cannot directly deposit anything small enough to be comparable to the wavelength of light,” said Pecunia. “But through electrodynamic inkjet printing we’ve been able to move beyond these limitations.”

̽��ֱ��researchers were able to deposit ultra-small ink droplets onto photonic crystals. ̽��ֱ��ink droplets are small enough that they can be ‘drawn’ on the crystals on demand as if from a very fine pen, and locally change the properties of the crystals so that light could be trapped. This technique enables the creation of many types of patterns onto the photonic crystals, at high speed and over a large area. Additionally, the patterns can be made of all sorts of printable materials, and the method is scalable, low-cost, and the photonic crystal is reusable since the ink can be simply washed away.

“This fabrication technique opens the door for diverse opportunities in fundamental and applied sciences,” said Brossard. “A potential direction is the creation of a high density of highly sensitive sensors to detect minute amounts of biomolecules such as viruses or cancer cells. This could also be a very useful tool to study some fundamental phenomena requiring very strong interaction between light and matter in new materials and create lasers on demand. Finally, this technology could also enable the creation of highly compact optical circuits which would guide the light and which could be modified by inkjet printing using the photonic crystal template.”

̽��ֱ��research was funded in part by the Engineering and Physical Sciences Research Council (EPSRC) and the Science and Technology Facilities Council (STFC).

Reference
Frederic S.F. Brossard et al. ‘Inkjet printed nanocavities on a photonic crystal template.’ Advanced Materials (2017). DOI: 10.1002/adma.201704425

A microscopic ‘pen’ that is able to write structures small enough to trap and harness light using a commercially available printing technique could be used for sensing, biotechnology, lasers, and studying the interaction between light and matter.

Previous efforts to combine these two areas had bumped into the limitations of conventional inkjet printing technology.

Vincenzo Pecunia

Light trapped by a tiny droplet on a photonic crystal surface.

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Yes

How artisans used colour printing to add another dimension to woodcuts

amb206 — Thu, 21 Jan 2016 16:59:06 +0000

̽��ֱ��fearsome dragon is dead, its body contorted and mouth hanging open. Above it, a triumphant St George sits astride a splendid horse. He wears full armour, his legs thrust forward, spurs glinting and lance held high. Atop his helmet, impossibly elaborate plumes and feathers cascade upwards and outwards. In the background, a city perches on a mountain top, silhouetted against a glowering sky.

This opulent image, worked in black and gold on a blue background, is one of the earliest European examples of colour printing used in fine art. It was created in 1507 by Lucas Cranach the Elder (1472–1553) at the request of his patron, Friedrich III, Elector of Saxony. Artisans working for Cranach, whose initials are worked into the design, used two wood blocks (black and gold) to print his masterful design of a horse and rider on to paper pre-painted with indigo. ̽��ֱ��medieval imagery contrasts with the strikingly modern Renaissance technology.

Cranach’s print is one of 31 German Renaissance woodcuts and a single drawing currently on display at the British Museum in an exhibition of early colour printing. All come from the British Museum’s collection but few have been shown to the public before. Together, they chart the ways in which advances in early print technology opened up new avenues for artists in creating a sense of movement, depth and opulence not possible in black and white.

̽��ֱ��exhibition German Renaissance Colour Woodcuts has been curated by Dr Elizabeth Savage (Faculty of English and Department of History of Art). Her pioneering research into archival collections in Germany and the UK, combined with her detailed grasp of the medium of woodblock printing, challenges accepted thinking about the use of colour in woodcuts, a craft-based technology associated almost exclusively with black-and-white or monochrome images.

When colour does appear in early woodcuts (for example St Dorothea and the Christ-Child, c.1450-1500) it has generally been applied by hand as a secondary process, often as a wash to draw attention to a significant aspect of the design. Given the considerable technical difficulties of colour printing using wood blocks, it was long assumed that colour printing did not develop on any significant scale until 1700, when Jakob Christoff Le Blon (1667-1741) invented a way to print all natural colours using only blue, red, yellow and black. His method became our CMYK: cyan, magenta, yellow, ‘key’ (black), following his order. Scholars thus assumed that early colour prints were extremely rare and judged them to be unrepresentative ‘outliers’.

Close analysis of colour images by Savage now reveals that, throughout the 1500s, thousands (and perhaps tens of thousands) of colour prints were in circulation in European countries. Furthermore, the range of colour woodblock prints in production varied from costly images, commissioned and collected by wealthy patrons, to more affordable ‘mass-produced’ prints designed to decorate the surfaces of furniture and the interiors of homes whose owners hankered after the latest styles of intarsia and marquetry – effects created by laborious and highly skilled inlay techniques.

One reason why so many colour prints have hidden in plain sight is that colour can be mistaken for paint. When the surfaces of prints are examined by an expert eye a different story may emerge. For instance, the pressure of the press often leaves tell-tale marks like indenting the design into the paper, forcing ‘ink squash’ into a raised outline, even giving the paper an almost sculptural relief. Savage collaborated with Gwen Riley Jones, a specialist in imaging gold at the ̽��ֱ�� of Manchester, to document the surface texture of the portrait of Holy Roman Emperor Charles V (1519) by Hans Weiditz (c.1500–c.1536). It can now be identified as the sixth image printed with gold in early modern Europe.

̽��ֱ��development of colour printing may have been technology-led, emerging from the workshops in the German cities of Augsburg and Strasbourg, among others, where competitive, innovative printers developed new ways to make their books stand out. But, in order to flourish, these advances required the backing of rich and powerful individuals whose status was closely tied to the conspicuous (and competitive) consumption of the latest in luxury goods, from textiles to prints.

“ ̽��ֱ��British Museum holds one of the world’s largest collections of colour prints, including unique examples from late medieval and early modern Germany. Early printers vied with each other to achieve stunning colouristic effects – 500 years before the advent of Photoshop,” says Savage. “We think of prints as being exactly repeatable black outlines on white paper, but some survive in many as 30 very different palettes. Their printers developed inks in royal blues, baby pinks, dusky oranges, lush greens, rich burgundies to create endless variety and unprecedented three-dimensional effects.”

Three prints, displayed side by side, illustrate how rivalry between members of the ruling elite stimulated important developments in colour printing. When in 1507 Friedrich III in Wittenberg sent images by Cranach of “knights printed from gold and silver” to his friend and competitor collector, the imperial advisor Konrad Peutinger in Augsburg, he created a friendly contest between two major artistic centres with artists and artisans stretching their skills to the limit in the quest for the most impressive image.

In response to the receipt of Cranach’s St George, Peutinger sent Friedrich a pair of larger colour woodcuts of St George and Maximillian I on horseback designed by Hans Burgkmair the Elder (1473–1531). With these woodcuts, Peutinger demonstrated that his Augsburg artists and craftsmen were able to outdo Frederick’s ostentatious effort. “Friedrich and Peutinger’s glittering exchange jump-started colour printing on a scale that we are only now beginning to appreciate,” said Savage. “It’s mind-boggling that one of Peutinger’s technicians corresponded directly with the Holy Roman Emperor about colour printing. Like Cranach’s nearly 24-karat gold printing ink on flimsy paper, it suggests the incredible value of these vivid breakthroughs.”

That extraordinary, short-lived, pre-Reformation heyday is thought to be the whole story, but Savage’s research recasts it as a short chapter. Dozens of colour impressions of German prints were known, by just a few artists, from the 1510s. This exhibition hints at the thousands of colour prints, circulating in perhaps tens of thousands of impressions, which were made and used across Germany. Rather than dying out before the Reformation, later European adaptions attest that the craft knowledge and market demand survived for generations and even spread abroad.

All prints are team efforts, with the artist normally considered the main producer. In the exhibition curated by Savage, the printer is the star player. Two colour impressions by Albrecht Dürer (1471–1528) and one by Hans Holbein (c.1497–1543) are on display, but neither ever designed a colour print. Instead, printers commissioned others to design and cut tone blocks to accompany the great masters’ ‘normal’ woodcuts. As a woodcut, Dürer’s portrait of Ulrich Varnbüler (1522) is a 16th-century German masterpiece; as a colour print, it’s a triumph of 17th-century Dutch marketing.

̽��ֱ��exhibition’s focus on printers, not artists, expands an apparently small and sporadic fine art movement into an ever-growing wave. Savage said: “People prayed with them, collected them, learned from them, decorated with them, upgraded cheap wooden furniture with them. Few were as stunning as Cranach’s golden, saintly knight, which is precisely the point. We’ve forgotten that colour woodcuts were normal, not exceptional, in the ‘golden age’ of print.”

German Renaissance Colour Woodcuts is on display in Room 90 on the fourth floor of the British Museum until Wednesday, 27 January 2016.

Inset images: Anonymous (German), St Dorothy of Caesarea and the Christ-child in an Apple Tree, c.1450-1500, British Museum 1895,0122.18, presented by William Mitchell © ̽��ֱ��Trustees of the British Museum and courtesy of the Centre for Heritage Imaging and Collection Care, ̽��ֱ�� of Manchester; Attr. Hans Weiditz, Holy Roman Emperor Charles V, 1519, British Museum 1862,0208.55 © ̽��ֱ��Trustees of the British Museum and courtesy of the Centre for Heritage Imaging and Collection Care, ̽��ֱ�� of Manchester; left: Albrecht Dürer, Ulrich Varnbüler, 1522, British Museum 1895,0122.739, presented by William Mitchell, centre and right: later editions printed with new tone blocks by Willem Jansz. Blaeu, c.1620, British Museum 1857,0613.345 and 1857,0613.345, © ̽��ֱ��Trustees of the British Museum.

An exhibition of early colour printing in Germany shines a light on the ways in which technology jump-started a revolution in image making. ̽��ֱ��British Museum show is curated by Dr Elizabeth Savage, whose research makes a radical contribution to an understanding of colour in woodcuts.

Friedrich and Peutinger’s glittering exchange jump-started colour printing on a scale that we are only now beginning to appreciate

Elizabeth Savage

Cranach George 1895,0122.264 37044001

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Yes

New graphene based inks for high-speed manufacturing of printed electronics

sc604 — Mon, 19 Oct 2015 10:38:54 +0000

A low-cost, high-speed method for printing graphene inks using a conventional roll-to-roll printing process, like that used to print newspapers and crisp packets, could open up a wide range of practical applications, including inexpensive printed electronics, intelligent packaging and disposable sensors.

Developed by researchers at the ̽��ֱ�� of Cambridge in collaboration with Cambridge-based technology company Novalia, the method allows graphene and other electrically conducting materials to be added to conventional water-based inks and printed using typical commercial equipment, the first time that graphene has been used for printing on a large-scale commercial printing press at high speed.

Graphene is a two-dimensional sheet of carbon atoms, just one atom thick. Its flexibility, optical transparency and electrical conductivity make it suitable for a wide range of applications, including printed electronics. Although numerous laboratory prototypes have been demonstrated around the world, widespread commercial use of graphene is yet to be realised.

“We are pleased to be the first to bring graphene inks close to real-world manufacturing. There are lots of companies that have produced graphene inks, but none of them has done it on a scale close to this,” said Dr Tawfique Hasan of the Cambridge Graphene Centre (CGC), who developed the method. “Being able to produce conductive inks that could effortlessly be used for printing at a commercial scale at a very high speed will open up all kinds of different applications for graphene and other similar materials.”

“This method will allow us to put electronic systems into entirely unexpected shapes,” said Chris Jones of Novalia. “It’s an incredibly flexible enabling technology.”

Hasan’s method, developed at the ̽��ֱ��’s Nanoscience Centre, works by suspending tiny particles of graphene in a ‘carrier’ solvent mixture, which is added to conductive water-based ink formulations. ̽��ֱ��ratio of the ingredients can be adjusted to control the liquid’s properties, allowing the carrier solvent to be easily mixed into a conventional conductive water-based ink to significantly reduce the resistance. ̽��ֱ��same method works for materials other than graphene, including metallic, semiconducting and insulating nanoparticles.

Currently, printed conductive patterns use a combination of poorly conducting carbon with other materials, most commonly silver, which is expensive. Silver-based inks cost £1000 or more per kilogram, whereas this new graphene ink formulation would be 25 times cheaper. Additionally, silver is not recyclable, while graphene and other carbon materials can easily be recycled. ̽��ֱ��new method uses cheap, non-toxic and environmentally friendly solvents that can be dried quickly at room temperature, reducing energy costs for ink curing. Once dry, the ‘electric ink’ is also waterproof and adheres to its substrate extremely well.

̽��ֱ��graphene-based inks have been printed at a rate of more than 100 metres per minute, which is in line with commercial production rates for graphics printing, and far faster than earlier prototypes. Two years ago, Hasan and his colleagues produced a prototype of a transparent and flexible piano using graphene-based inks, which took between six and eight hours to make. Through the use of this new ink, more versatile devices on paper or plastic can be made at a rate of 300 per minute, at a very low cost. Novalia has also produced a printed DJ deck and an interactive poster, which functions as a drum kit using the same method.

Hasan and PhD students Guohua Hu, Richard Howe and Zongyin Yang of the Hybrid Nanomaterials Engineering group at CGC, in collaboration with Novalia, tested the method on a typical commercial printing press, which required no modifications in order to print with the graphene ink. In addition to the new applications the method will open up for graphene, it could also initiate entirely new business opportunities for commercial graphics printers, who could diversify into the electronics sector.

“ ̽��ֱ��UK, and the Cambridge area in particular, has always been strong in the printing sector, but mostly for graphics printing and packaging,” said Hasan, a Royal Academy of Engineering Research Fellow and a ̽��ֱ�� Lecturer in the Engineering Department. “We hope to use this strong local expertise to expand our functional ink platform. In addition to cheaper printable electronics, this technology opens up potential application areas such as smart packaging and disposable sensors, which to date have largely been inaccessible due to cost.”

In the short to medium term, the researchers hope to use their method to make printed, disposable biosensors, energy harvesters and RFID tags.

̽��ֱ��research was supported by grants from the Engineering and Physical Sciences Research Council's Impact Acceleration Account and a Royal Academy of Engineering Research Fellowship. ̽��ֱ��technology is being commercialised by Cambridge Enterprise, the ̽��ֱ��’s commercialisation arm.

A low-cost, high-speed method for printing electronics using graphene and other conductive materials could open up a wide range of commercial applications.

Being able to produce conductive inks that could effortlessly be used for printing at a commercial scale at a very high speed will open up all kinds of different applications for graphene and other similar materials

Tawfique Hasan

Roll-to-roll printing of graphene ink

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Yes

̽��ֱ�� spin-out wins green award

sc604 — Wed, 27 Aug 2014 14:24:18 +0000

Reduse, which was founded 2014, was named the winner at a ceremony held earlier this month in London for the UK’s top climate start-ups.

David Leal, Reduse’s Chief Scientist, invented the ‘Unprinter’ during his PhD research under the supervision of Dr Julian Allwood in the Low Carbon Materials Processing Group at the Engineering Department.

Their invention is able to remove print from laser-printed paper, and this process can be repeated several times without damaging the fibres of the paper, providing cost savings and CO2 reductions. Just one office employee can use up to 10,000 sheets of paper every year, most of which are thrown away after only a few days. Along with saving forests from being used for new paper, reusing paper could save an additional 50-80% in carbon emissions over recycling.

Climate-KIC (Knowledge and Innovation Community) shortlisted Reduse as a finalist in their annual UK Venture Competition, following the company’s involvement in the Climate-KIC Accelerator Programme, which provides up to €95,000 funding to the most promising carbon start-ups in Europe.

Reduse were one of nine finalists who competed for the prize at the Royal College of Music in London.

“We are of course delighted to have won this competition. This is more proof that we are on the right track to solving the incredible waste that is being generated by printing," said Hidde-Jan Lemstra, CEO of Reduse.

̽��ֱ��company recently recruited Tony Dunn to become their new Chief Technology Officer. He has over twenty years’ experience with product design and development, and will lead the development of the Unprinter. Reduse has already started raising its first round of funding and looks to gain a £224,000 grant from the Technology Strategy Board.

̽��ֱ�� of Cambridge spin-out Reduse, which has developed a technology to remove print from paper allowing it to be reused several times before being recycled, has won the Venture Competition, organised by the Climate-KIC UK , the EU’s main climate innovation initiative.

This is more proof that we are on the right track to solving the incredible waste that is being generated by printing.

Hidde-Jan Lemstra

Turinboy via Flickr

A crumpled paper ball

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