A diamond is a rare and precious find which has been treasured by humans for thousands of years. It’s the gift of love; a luxury product; an iconic badge of the glamourous. Or is it more important than that? Researchers at the University of Warwick, and collaborating universities across the UK, are proving that a diamond is much more than just a sparkly bauble. Scientists can grow synthetic diamond in the lab with the vision of using it in a huge range of innovative applications.

Professor Julie Macpherson, an electrochemist and materials scientist from The University of Warwick’s Department of Chemistry, explains:

“Diamond is a material for the 21st century. Not only can it be grown routinely to demand in a laboratory, but its applications are limitless and we are only now scratching the surface of this most amazing material. At Warwick we have a team dedicated to uncovering its uses and finding new solutions to some of the world’s challenges.”

Crystal structure

Diamond is a form of carbon, like charcoal and graphite. But where the carbon atoms in the graphite of pencils are arranged in sheets which make it easy to break apart, diamond has a unique arrangement of atoms which gives it its many valued qualities. Each carbon atom in a diamond is bonded to four others in a three dimensional crystal structure which makes it, among other things, the hardest substance in the universe. Diamond is an electrical insulator with the highest thermal conductivity of any bulk material at room temperature. It is also optically transparent from the ultra-violet into the infrared and microwave regions of the electromagnetic spectrum as well as being biologically and chemically inert.

When making the synthetic diamonds, scientists can also use tricks borrowed from nature to change the properties of diamond. For example, by replacing one in 1000 of the carbon atoms with boron, the material goes from transparent to black and from electrically insulating to conducting.

“Diamond has an enviable list of properties which makes it a really useful material in lots of applications – some of which we know already and can work to improve, and some of which we can only speculate on and that we may be able to do something with in the future,” continues Professor Macpherson.

“Diamond technology is currently being used in precision engineering tools, to improve the purity of sound and to incinerate pollutants in waste water. Areas where I expect diamond to make breakthroughs in the future include quantum computing and engineering, chemical sensing, single molecule structure identification, laser technology and biomedicine.

"It’s an exciting time to be in diamond science and technology research!”

The acid test

Professor Macpherson is carrying out her own research into using black diamond as a pH sensor. She has been recently awarded a Royal Society Innovation Award to take her work forward in partnership with industry.

She explains: “Testing pH – how acid or alkali something is – is one of the most important and commonly carried out tests for a whole range of industries, including food manufacturing, household chemicals, water quality and brewing. You can tell a lot from a pH test. The technology currently being used is over 100 years old. It’s a simple test but it has its imperfections. It involves measuring the proton concentration in a solution using a thin glass membrane electrode, which is a very fragile component and does not withstand challenging conditions. Alternative technology must be found.”

Professor Macpherson has worked on diamond for more than ten years and has always had ideas about how it could be used to improve chemical sensing. She says: “I knew that diamond had the potential to overcome a lot of problems and could ultimately be used to detect a whole range of different chemicals in solution. For pH the aim is to replace the glass bulb with solid diamond. The high stability of diamond and biocompatibility (it is just carbon after all) raises interesting questions about possible medical sensing application. Ultimately you could imagine tiny diamond sensors being placed directly in the body and into blood vessels, continually monitoring vital parameters such as pH, oxygen and temperature which provide an early warning indicator of serious problems arising. This has real benefits in emergency situations and treating life changing or threatening injuries.”

Valley of death

Professor Macpherson has already developed prototype pH sensors from a 1 mm sized diamond piece, specially machined with a laser to introduce pH selectivity to the surface. Now, with the Royal Society award, she is working towards testing the sensor in real industry situations and challenging environments.

She says: “We call it ‘crossing the valley of death’. We can show this thing works in the very controlled environment of the lab, but we need to show that the system behaves just as well in the field and then ultimately, hopefully, look for commercialization opportunities.”

Professor Macpherson is not the only diamond scientist at Warwick. She works within an interdisciplinary group with colleagues from across the university. With her colleague Professor Mark Newton in Physics, they head up the training for the next generation of diamond scientists from across the UK. Warwick is the hub for the EPSRC Centre for Doctoral Training in Diamond Science and Technology, which is tasked with training 60 doctoral students in the field of diamond research over the next five years.

Professor Macpherson concludes: “This field has massive potential for many industries so investment in future scientists is key. Our young researchers are continually pushing back the frontiers to discover more and more ways in which diamonds can become the world’s best friend.”

Published
27 June 2017

Julie Macpherson is Royal Society Industry Fellow and Professor of Chemistry at the University of Warwick. Her research interests include the development of new electrochemical based sensors for a variety of different applications. She is significantly involved in the UK's first Collaborative Doctoral Training (CDT) Centre in Diamond Science and Technology (DST) and holds a Royal Society Industry Fellowship with Element Six, aimed specifically at the development of boron-doped diamond electrochemical sensors. She was recently awarded (March 2017) the Royal Society Innovation award for her work in this area.

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