Physicists at the University of Sussex are developing a new material for touch-screen devices that has already proved to be more flexible and to have higher conductivity than current technologies.
Working in collaboration with M-SOLV Ltd, a touchsensor manufacturer based in Oxford, Professor Alan Dalton and his team have shown that silver nanowires, which are more than a thousand times thinner than a human hair, are a viable alternative to the currently used material, indium tin oxide (ITO), which is expensive to source and process and brittle. Their research sought alternative materials to overcome the challenges of ITO, which is mined largely in China and Canada and is suffering from uncertainty over supply.
Graphene, carbon nanotubes and random metal nanowire films are among the alternatives being explored but the new study, carried out while Professor Dalton was at the University of Surrey, showed how silver nanowire films have emerged as the strongest competitor, due to transmittances and conductivities that can match and readily exceed those of ITO. Using a technique, called ‘ablation’, which involves the removal of material using a laser beam to produce individual electrode patterns, the team produced a fully operating five-inch multi-touch sensor, identical to those typically used in smartphone technology. They found it performed comparably to one based on ITO but used significantly less energy to produce.
Professor Dalton said: “Not only does this flexible material perform very well, we have shown that it is a viable alternative to ITO in practical devices. The fact we are able to produce devices using similar methods as currently in use, but in a less energy-intensive way, is an exciting step towards flexible gadgets that do not just open the door for new applications, but do so in a much greener way.” The team also showed that by using ‘ultrasonication’, which involves applying high-frequency sound to the material to manipulate the length of the nanosized rods of silver, they could tailor the properties for a range of other applications. Matthew Large, an author on the research, said: “Our research hasn’t just confirmed silver nanowires as a potential replacement touchscreen material but has gone one step further in showing how ultrasonication can allow us to tailor performance capabilities.
“This allows us to tune how transparent or how conductive our films are, which is vital for optimising these materials for future technologies like flexible solar cells and roll-able electronic displays.” Maria Cann, a technologist from M-SOLV and an author on the paper, said: “We are seeing a lot of interest from our customers in silver nanowire films as an ITO replacement in devices. This work is a really important step in establishing exactly which sensor designs can make good nanowire products. The fact that the nanowire films are processed by the same laser techniques as ITO makes the transition from ITO to nanowires really straightforward. It won’t be long before we are all using nanowires in our electronic devices.”
The team, who moved from the University of Surrey to the University of Sussex this year, are now looking to develop the scalability of the process to make it more industrially viable. Funded by Innovate UK and EPSRC, the team are collaborating with M-SOLV and a graphene supplier Thomas Swan to use a nanowire and graphene combination in the electrodes to markedly reduce the cost.
On the road
The logistics members of the Chemical Business Association (CBA) completed more than one million journeys to deliver more than four and a half million tonnes of chemicals in 2015 to virtually every sector of the UK economy, according to recently-released figures. The figures are contained in the CBA’s annual Logistic Index report, now in its tenth year.
Minister welcomed
The Chemical Industries Association, which represents chemical and pharmaceutical businesses across the UK, has welcomed the industrial strategy set out by new Prime Minister Theresa May. It said that the recognition of the strategy in a cabinet minister’s job title is hugely significant. Steve Elliott, Chief Executive of the Association, said “We have long campaigned for greater clarity and commitment from Government on industrial strategy. The shape of the new Government and the inclusion of energy as well as the explicit naming of industrial strategy in the Business Department’s responsibilities marks an important start. What we now need are policies that reflect this understanding.