Heralded as one of the most important developments in ultrasonic cleaning in decades, a new piece of technology that uses only cold water and ultrasonic bubbles has the potential to revolutionise cleaning in the healthcare industry and beyond.
Currently prototyped as a hand-held, portable device, StarStream generates a stream of cold water at 2.1 litres/min from a 10mm diameter circular nozzle, down which an ultrasonic field is projected. The device creates bubble clouds that clean to a very high level surfaces with which they come into contact, without any need for detergents or chemicals. It could provide healthcare providers with a low-cost, eco-friendly cleaning alternative.
Invented and patented by Professor Leighton – known worldwide for ground-breaking research in acoustics in liquids – and Dr Peter Birkin, a Senior Lecturer in Electrochemistry at the University of Southampton, the technology has been exclusively licensed by Cardiff-based Ultrawave, which is in the process of commercialising the product; prototypes are now being trialled by experts across the world.
The technology works by propagating ultrasound energy through a low pressure flow of cold water. This causes ripples in the walls of microscopic bubbles in the water and generates high shearing forces in the liquid close to the bubble’s wall. This shear causes the bubbles to become abrasive, removing dirt and bacteria as they scour against surfaces, cleaning them to a very high standard.
Ultrasonic bubbles are especially effective at getting into hard-to-reach cracks and crevices to completely remove soil and bacteria. Recent independent tests found that technology is 1,000 times more effective than water alone in decontaminating the micro-organism Pseudomonas aeruginosa, a major cause of hospital acquired infections.
For the healthcare sector, the technology has the potential to speed up and improve significantly the current three-stage instrument decontamination process of gross soil removal, disinfection and sterilisation.
As the invention applies a direct stream of water onto the item, it removes any danger of ‘drag-through’ contamination during the first stage of gross soil removal. This can happen when dipping an item into a bath or tank and then lifting it back out through contaminated liquid. Using StarStream, the item is cleaned and rinsed simultaneously and uniformly across the entire area.
The technology also offers the potential to combine the first two stages of the current decontamination process – the removal of gross soil and the disinfection stage. The second stage usually involves high temperatures, chemicals and detergents to reach a satisfactory log reduction rate in bacteria, but using only cold water and ultrasonic energy, StarStream is already achieving a 3 log reduction – a 99.9% kill rate in potentially harmful micro-organisms.
Further tests are in the pipeline using a biocide with the water, which will see its log reduction rating increase dramatically. This could allow StarStream to conveniently cover both stages.
Undergoing trials
‘There are many studies and trials on-going, which are delivering exciting results, and we want to partner with more businesses and organisations in the healthcare industry and beyond to test it further and help us explore its full potential,’ said John Melville, Managing Director, Ultrawave. ‘It’s a very exciting piece of technology. The cleaning industry hasn’t seen a development like this in many, many years.
‘In the NHS, there is a real opportunity to revolutionise the decontamination process using StarStream technology. It will significantly reduce the resources used, including disinfectants, electricity and water, which will save costs and the environment. It will also cut back on the time the decontamination process takes, while reducing opportunities for human error by removing the number of stages an item has to go through before it reaches a 100% kill rate.’
The technology is significantly more effective at removing biofilms grown on a surface than a water stream alone
The technology’s ability to clean using only cold water also leads to significant reductions in power bills. Studies have also shown it can produce up to 97% energy savings compared with current commercial products, which is appealing to industries looking to reduce costs and improve their environmental footprint. Because it works without detergent, it minimises the risk of run-off polluting groundwater and streams, and simplifies the task of turning the used water back into safe drinking water.
The technology is also portable, opening up a range of new opportunities for items that cannot currently be cleaned using ultrasonic cleaning tanks or baths because they themselves are not portable.
Inventor Professor Leighton said: ‘We believe that it is very important to undertake fundamental multidisciplinary science and engineering because that produces step-change, as opposed to incremental, progress. But it is equally vital that those breakthroughs do not stay between the pages of an academic journal, but get out into the wider world to do the basic job of helping people and saving lives.
We are entering a new era, when the importance of cleaning will again be re-emphasised
‘We are entering a new era, when the importance of cleaning will again be re-emphasised. Periodically in history, pioneers such as Aulus Cornelius Celsus, Ignaz Semmelweis and Florence Nightingale have changed healthcare and saved lives by emphasising the need for cleanliness. But in the past 50 years, the ready availability of antibiotics and other antimicrobials has perhaps made us complacent, allowing the alarming increase in resistant microbe strains. By 2050, drug-resistant diseases could be killing more people than cancer – an extra 10 million deaths per year. They would also cause a loss to the global output of US$100 trillion – equivalent to a sum greater than the current global economy.
‘Cleaning is vital. If we can stop the microbe entering the body, we will not have an infection to fight. If we can stop it entering the wider world, we remove the ability for strains to travel between hosts and develop resistance,’ he said.
A wide range of applications
The initial research into disruptive technologies led by Leighton and Birkin, along with their former students Doug Offin and Chris Vian at the University of Southampton, using funding from the Defence Science and Technology Laboratory, led to the discovery of the technology in 2010. A huge range of applications and samples were tested with success, including blood, human tissue, soot, toothpaste, soil, peanut butter, vegetables, cloth, oil, make-up, Vaseline and skin.
It is currently being tested by the Network for Anti-Microbial Resistance and Infection Prevention (NAMRIP), founded by Professor Leighton in 2015, and already has attracted more that £1m investment from the Engineering and Physical Sciences Research Council, and the Medical Research Council. In NAMRIP, engineers, physical scientists, clinicians and social scientists are working together to integrate responses to the technology in the fields of dentistry and surgical instrument cleaning and others. It has already been successfully tested in joint replacements, cleaning bones before transplant, and in cleaning surgical instruments for brain tissue decontamination, which is especially important in tackling CJD. It has also been tested for dental bacteria removal and hand-washing in healthcare.
Recent research by Dr Leighton and the University of Southampton into the removal of dental biofilms illustrated the power of StarStream. Results showed that the technology was significantly more effective at removing biofilms grown on a surface than a water stream alone. Water alone caused a 0.10 log reduction (20.7%) in biomass and 0.17 log reduction (33.8%) in thickness in S. mutans biofilm. The StarStream caused a further 2.3 log reduction in biomass (99.5% reduction compared with untreated water) and a 2.9 log reduction in thickness – a 99.9% reduction in comparison. Similar results were recorded for A. naeslundii biofilms and S. oralis biofilm.
If we can stop the microbe entering the wider world, we remove the ability for strains to travel between hosts and develop resistance
In 2011, the technology won the Royal Society’s Brian Mercer Award for Innovation. This provided the team at the University of Southampton with a new platform for the technology and an additional £250,000 in funding to look into further applications. The team then approached Ultrawave, which has been designing and manufacturing ultrasonic cleaning systems for 25 years, for a collaboration to help bring the technology to market. Ultrawave has the exclusive licence for StarStream and is working to commercialise it in partnership with Leighton and the University of Southampton.
In 2012, StarStream collected the Institute of Chemical Engineering Award for Water Management and Supply for its potential to generate significant savings in water use in a range of cleaning applications, and in 2014 it was named Best New Product of the Year from S-Lab (Safe, Successful and Sustainable Laboratories).
Further studies are needed to fully comprehend the scope and impact of this new technology and Ultrawave hopes to have a product ready next year, but it is clear that this technology will change the future of the industry and provide the healthcare industry, and many others, with vastly improved cleaning and decontamination options going forward.
Bibliography
1. Leighton, T. G. (2011), Journal of Computational Acoustics, 19(1), 1–25
2. Leighton, T. G., Birkin, P. R. and Offin, D. (2013), A new approach to ultrasonic cleaning, Proceedings of the International Congress on Acoustics, Vol. 19, paper 075029 DOI: 10.1121/1.4799209
3. http://jdr.sagepub.com/content/early/2015/06/04/0022034515589284
4. http://www.southampton.ac.uk/engineering/research/projects/starstream.page?
5. http://resource.isvr.soton.ac.uk/staff/pubs/PubPDFs/Pub12503.pdf