Graphene Flagship researchers from Trinity College Dublin in collaboration with the National Graphene Institute (NGI) at The University of Manchester, have used graphene to make a polysilicone polymer, known commonly as the novelty children’s material Silly Putty®, conduct electricity. Using this conductive polymer they found that they were about to create sensitive electromechanical sensors.
The team’s findings have been published in the journal Science*.
This research, led by Professor Jonathan Coleman, Trinity College Dublin, in collaboration with Professor Robert Young of The University of Manchester, potentially offers exciting possibilities for applications in new, inexpensive devices and diagnostics in healthcare and other sectors.
Professor Coleman, Investigator in AMBER and Trinity’s School of Physics along with postdoctoral researcher Conor Boland (both seen in the image below), discovered that the electrical resistance of putty infused with graphene (‘G-putty’) was extremely sensitive to the slightest deformation or impact, having a gauge factor >500. They mounted the G-putty onto the chest and neck of human subjects and used it to measure breathing, pulse and even blood pressure. It showed unprecedented sensitivity as a sensor for strain and pressure, hundreds of times more sensitive than current sensors. The G-putty also works as a very sensitive impact sensor, able to detect the footsteps of small spiders.
Professor Coleman said: “What we are excited about is the unexpected behaviour we found when we added graphene to the polymer, a cross-linked polysilicone. This material is well known as the children’s toy Silly Putty. It is different from familiar materials in that it flows like a viscous liquid when deformed slowly but bounces like an elastic solid when thrown against a surface. When we added the graphene to the silly putty, it caused it to conduct electricity, but in a very unusual way. The electrical resistance of the G-putty was very sensitive to deformation with the resistance increasing sharply on even the slightest strain or impact. Unusually, the resistance slowly returned close to its original value as the putty self-healed over time.”
He continued, “While a common application has been to add graphene to plastics in order to improve the electrical, mechanical, thermal or barrier properties, the resultant composites have generally performed as expected without any great surprises. The behaviour we found with G-putty has not been found in any other composite material. This unique discovery will open up major possibilities in sensor manufacturing worldwide.”
In their paper the team show that following the addition of graphene to the polymer it not only became conductive (reaching approximately 0.1 S/m at approximately 15 volume % of graphene) but importantly, it retained its viscoelasticity characteristics. The graphene sheets are able to respond to polymeric deformation in a time dependant manor, forming networks that break and reform during mechanical deformation. This changes the conductivity of the polymeric material, enabling it to sense by deformation.
Following the initial development work at Trinity College Dublin scientists at the NGI at The University of Manchester analysed the structure of the material and were able to develop a mathematical model of the deformation of the material which explains the effect of its structure upon its mechanical and electrical properties.
Robert Young, Professor of Polymer Science and Technology at the NGI said: “The endless list of potential applications of graphene, never ceases to amaze me. We have now developed a new high-performance sensing material, ‘G-putty’, that can monitor deformation, pressure and impact at a level of sensitivity that is so precise that it allows even the footsteps of small spiders to be monitored.
“It will have many future applications in sensors, particularly in the field of healthcare. The collaboration has been undertaken under the umbrella of the European Graphene Flagship, in which Trinity College Dublin and The University of Manchester both play a prominent role. It is an excellent example of what is being achieved in the Flagship programme.”
Learn more: G-Putty sensors – an unexpected breakthrough
Chemists from Trinity College Dublin, in collaboration with RCSI, have devised a revolutionary new scanning technique that produces extremely high-res 3D images of bones — without exposing patients to X-ray radiation.
The chemists attach luminescent compounds to tiny gold structures to form biologically safe ‘nanoagents’ that are attracted to calcium-rich surfaces, which appear when bones crack – even at a micro level. These nanoagents target and highlight the cracks formed in bones, allowing researchers to produce a complete 3D image of the damaged regions.
The technique will have major implications for the health sector as it can be used to diagnose bone strength and provide a detailed blueprint of the extent and precise positioning of any weakness or injury. Additionally, this knowledge should help prevent the need for bone implants in many cases, and act as an early-warning system for people at a high risk of degenerative bone diseases, such as osteoporosis.
The research, led by the Trinity team of Professor of Chemistry, Thorri Gunnlaugsson, and Postdoctoral Researcher, Esther Surender, has just been published in the leading journal Chem, a sister journal to Cell, which is published by CellPress. The article can be viewed here.
Professor Gunnlaugsson said: “This work is the outcome of many years of successful collaboration between chemists from Trinity and medical and engineering experts from RCSI. We have demonstrated that we can achieve a three-dimensional map of bone damage, showing the so-called microcracks, using non-invasive luminescence imaging. The nanoagent we have developed allows us to visualise the nature and the extent of the damage in a manner that wasn’t previously possible. This is a major step forward in our endeavour to develop targeted contrast agents for bone diagnostics for use in clinical applications.”
The work was funded by Science Foundation Ireland and by the Irish Research Council, and benefited from collaboration with scientists at RCSI (Royal College of Surgeons in Ireland), led by Professor of Anatomy, Clive Lee.
Professor Lee said: “Everyday activity loads our bones and causes microcracks to develop. These are normally repaired by a remodelling process, but, when microcracks develop faster, they can exceed the repair rate and so accumulate and weaken our bones. This occurs in athletes and leads to stress fractures. In elderly people with osteoporosis, microcracks accumulate because repair is compromised and lead to fragility fractures, most commonly in the hip, wrist and spine. Current X ray techniques can tell us about the quantity of bone present but they do not give much information about bone quality.”
He continued: “By using our new nanoagent to label microcracks and detecting them with magnetic resonance imaging (MRI), we hope to measure both bone quantity and quality and identify those at greatest risk of fracture and institute appropriate therapy. Diagnosing weak bones before they break should therefore reduce the need for operations and implants – prevention is better than cure.”
In addition to the unprecedented resolution of this imaging technique, another major step forward lies in it not exposing X-rays to patients. X-rays emit radiation and have, in some cases, been associated with an increased risk of cancer. The red emitting gold-based nanoagents used in this alternative technique are biologically safe – gold has been used safely by medics in a variety of ways in the body for some time.
Dr Esther Surender, Postdoctoral Researcher at Trinity, said: “These nanoagents have great potential for clinical application. Firstly, by using gold nanoparticles, we were able to lower the overall concentration of the agent that would have to be administered within the body, which is ideal from a clinical perspective. Secondly, by using what is called ‘two-photon excitation’ we were able to image bone structure using long wavelength excitation, which is not harmful or damaging to biological tissues.”
She added: “These nanoagents are similar to the contrast agents that are currently being utilised for MRI within the clinic, and hence have the potential to provide a novel means of medical bone diagnosis in the future. Specifically, by replacing the Europium with its sister ion Gadolinium, we can tune into the MRI activity of these nanoagents for future use alongside X-ray and computed tomography (CT) scans.”
Researchers at the CRANN nanoscience institute at Trinity College Dublin have discovered a new clean energy material that will increase the adoption of hydrogen as a fuel in energy-efficient transport.
Hydrogen has been described as the ultimate clean energy source and, potentially, a real alternative to fossil fuels.
It is seen as very attractive as it is a pollution-free fuel and energy carrier that would satisfy much of the energy requirements of our society.
Hydrogen is readily prepared by splitting water electrically into its component parts hydrogen and oxygen; a process called electrolysis. However, this process requires a significant energy input.
‘Our disruptive materials breakthrough is momentous as it means much more energetically efficient and more economical hydrogen energy’
– PROF MIKE LYONS, CRANN
Trinity College (Irish: Coláiste na Tríonóide), formally known as the College of the Holy and Undivided Trinity of Queen Elizabeth near Dublin, is the sole constituent college of the University of Dublin in Ireland.
The college was founded in 1592 as the “mother” of a new university, modelled after the collegiate universities of Oxford and of Cambridge, but, unlike these, only one college was ever established; as such, the designations “Trinity College” and “University of Dublin” are usually synonymous for practical purposes. It is one of the seven ancient universities of Britain and Ireland, as well as Ireland’s oldest university.
Originally established outside the city walls of Dublin in the buildings of the dissolved Augustinian Priory of All Hallows, Trinity College was set up in part to consolidate the rule of the Tudor monarchy in Ireland, and it was seen as the university of the Protestant Ascendancy for much of its history. Although Catholics and Dissenters had been permitted to enter as early as 1793, certain restrictions on their membership of the college remained until 1873 (professorships, fellowships and scholarships were reserved for Protestants), and the Catholic Church in Ireland forbade its adherents, without permission from their bishop, from attending until 1970. Women were first admitted to the college as full members in 1904.
Trinity College is now surrounded by Dublin and is located on College Green, opposite the former Irish Houses of Parliament. The college proper occupies 190,000 m2 (47 acres), with many of its buildings ranged around large quadrangles (known as ‘squares’) and two playing fields. Academically, it is divided into three faculties comprising 25 schools, offering degree and diploma courses at both undergraduate and postgraduate levels.
In 2011, it was ranked by the Times Higher Education World University Rankings as the 110th best university in the world, by the QS World University Rankings as the 65th best, by the Academic Ranking of World Universities as within the 201-300 range, and by all three as the best university in Ireland. The Library of Trinity College is a legal deposit library for Ireland and the United Kingdom, containing over 4.5 million printed volumes and significant quantities of manuscripts (including the Book of Kells), maps and music.
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Trinity College Dublin research articles from Innovation Toronto
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