Tag Archives: Alan B. Dalton

Replacing the indium tin oxide (ITO) electrodes in smartphones?

Leave a reply

Physicists have developed silver nanowires that could be used to replace the indium tin oxide electrodes found in touchscreens for smartphones, tablets, and more. From a Sept. 14, 2016 news item on Nanowerk,

Physicists at the University of Sussex are at an advanced stage of developing alternative touchscreen technology to overcome the shortfall in the traditional display, phone and tablet material that relies on electrodes made from indium tin oxide (ITO).

They have now shown that not only is the material suitable for touchscreens, but that it is possible to produce extremely small patterns (pixels), small enough for high definition LCD displays, such as smartphones and the next generation of television and computer screens.

The study, led by Sussex Professor of Experimental Physics Alan Dalton, investigates some of the intricacies of patterning silver nanowire films to produce detailed electrode structures. …

A Sept. 13, 2016 University of Sussex press release, which originated the news item, describes why this research presents some exciting possibilities (Note: Links have been removed),

Previous research by Professor Dalton’s group has shown that silver nanowires not only match the transmittances and conductivities of ITO films but exceed them. This makes the material very attractive for touch screens. However, the group have now shown, for the first time, that this type of nanomaterial is compatible with more demanding applications such as LCD and OLED displays.

Professor Dalton said: “Display technologies such as LCD and OLED form images using pixels. Each pixel of these displays is further broken down into subpixels; typically, one each for red, green and blue colours. In the display in a smartphone, for example, these subpixels are less than a sixth of the width of a human hair – which is also similar in length to the silver nanowires used in our research.”

Dr Matthew Large, the lead author of the paper, expanded: “In this research we have applied a mathematical technique to work out the smallest subpixel size we can make without affecting the properties of our nanowire electrodes. This method was originally developed to describe how phase changes like freezing happen in very small spaces, The results tell us how to tune our nanowires to meet the requirements of any given application.”

In collaboration with their industrial partners, M-SOLV based in Oxford, the team – which is now looking to apply these research results to commercial projects – has also demonstrated that the incorporation of silver nanowires into a multi-touch sensor actually reduces the production cost and energy usage.

Professor Dalton said: “Silver nanowire and silver nanowire/graphene hybrids are probably the most viable alternatives to existing technologies. Others scientists have studied several alternative materials, but the main issue is that the majority of other materials do not effectively compete with ITO or they are too costly to produce, at least at the moment.”

Here’s a link to and a citation for the paper,

Finite-size scaling in silver nanowire films: design considerations for practical devices by Matthew J. Large, Maria Cann, Sean P. Ogilvie, Alice A. K. King, Izabela Jurewicz, and Alan B. Dalton. Nanoscale, (issue 28) 2016,8, 13701-13707 DOI: 10.1039/C6NR03960J First published online 27 Jun 2016

This paper is behind a paywall.

Dexter Johnson’s Sept. 16, 2016 posting (on his Nanoclast blog on the IEEE [Institute of Electrical and Electronics Engineers] website) adds some new detail (Note: Links have been removed),

The field of nanomaterials vying to replace indium tin oxide (ITO) as the transparent conductor that controls display pixels in touch screen displays is getting crowded. We’ve seen materials including carbon nanotubes, silver nanowires, and graphene promoted as the heir apparent for this application.

Now, researchers at the University of Sussex in England have introduced a strong contender into the battle to replace indium tin oxide: a hybrid material consisting of silver nanowires that are linked together with graphene.

“The hybrid material is a lot cheaper due to the fact that we only need to use a fraction of the nanowires normally required to attain the properties of ITO,” …

Monitoring health with graphene rubber bands

Leave a reply

An Aug. 20, 2014 news item on Azonano highlights graphene research from the University of Surrey (UK) and Trinity College Dublin (Ireland),

Although body motion sensors already exist in different forms, they have not been widely used due to their complexity and cost of production.

Now researchers from the University of Surrey and Trinity College Dublin have for the first time treated common elastic bands with graphene, to create a flexible sensor that is sensitive enough for medical use and can be made cheaply.

An Aug. 15, 2014 University of Surrey press release (also on EurekAlert), which originated the news item, describes the innovation (Note: A link has been removed),

Once treated, the rubber bands remain highly pliable. By fusing this material with graphene – which imparts an electromechanical response on movement – the material can be used as a sensor to measure a patient’s breathing, heart rate or movement, alerting doctors to any irregularities.

“Until now, no such sensor has been produced that meets these needs,” said Surrey’s Dr Alan Dalton. “It sounds like a simple concept, but our graphene-infused rubber bands could really help to revolutionise remote healthcare – and they’re very cheap to manufacture.”

…

“These sensors are extraordinarily cheap compared to existing technologies. Each device would probably cost pennies instead of pounds, making it ideal technology for use in developing countries where there are not enough medically trained staff to effectively monitor and treat patients quickly.” [commented corresponding author, Professor Jonathan Coleman from Trinity College, Dublin]

Trinity College Dublin issued an Aug. 20, 2014 press release, which provides a little more technical detail and clarifies who led the team for anyone who may been curious about the matter,

The team – led by Professor of Chemical Physics at Trinity, Jonathan Coleman, one of the world’s leading nanoscientists – infused rubber bands with graphene, a nano-material derived from pencil lead which is 10,000 times smaller than the width of a human hair. This process is simple and compatible with normal manufacturing techniques. While rubber does not normally conduct electricity, the addition of graphene made the rubber bands electrically conductive without degrading the mechanical properties of the rubber. Tests showed that any electrical current flowing through the graphene-infused rubber bands was very strongly affected if the band was stretched. As a result, if the band is attached to clothing, the tiniest movements such as breath and pulse can be sensed.

The discovery opens up a host of possibilities for the development of wearable sensors from rubber, which could be used to monitor blood pressure, joint movement and respiration. Other applications of rubber-graphene sensors could be in the automotive industry (to develop sensitive airbags); in robotics, in medical device development (to monitor bodily motion), as early warning systems for cot death in babies or sleep apnoea in adults. They could also be woven into clothing to monitor athletes’ movement or for patients undergoing physical rehabilitation.

…

Professor Coleman said: “Sensors are becoming extremely important in medicine, wellness and exercise, medical device manufacturing, car manufacturing and robotics, among other areas. Biosensors, which are worn on or implanted into the skin, must be made of durable, flexible and stretchable materials that respond to the motion of the wearer. By implanting graphene into rubber, a flexible natural material, we are able to completely change its properties to make it electrically conductive, to develop a completely new type of sensor. Because rubber is available widely and cheaply, this unique discovery will open up major possibilities in sensor manufacturing worldwide.”

Here’s a link to and a citation for the paper,

Sensitive, High-Strain, High-Rate Bodily Motion Sensors Based on Graphene–Rubber Composites by Conor S. Boland, Umar Khan, Claudia Backes, Arlene O’Neill, Joe McCauley, Shane Duane, Ravi Shanker, Yang Liu, Izabela Jurewicz, Alan B. Dalton, and Jonathan N. Coleman. ACS Nano, Article ASAP DOI: 10.1021/nn503454h Publication Date (Web): August 6, 2014

Copyright © 2014 American Chemical Society

This paper is open access (I was able to open the HTML version this morning, Aug. 20, 2014). As well the researchers have made this image illustrating their work available,

[downloaded from http://pubs.acs.org/doi/full/10.1021/nn503454h]

[downloaded from http://pubs.acs.org/doi/full/10.1021/nn503454h]