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The extraordinary potential of bubble acoustics

Tackling problems as diverse as antimicrobial resistance and explosive detection.

Published: 7 September 2016

Researchers at Southampton have been exploiting the characteristics of bubbles and have found the potential to tackle problems as diverse as antimicrobial resistance and explosive detection.

Bubbles – in the form of pockets of gas surrounded by liquid – are extremely powerful entities for interacting with sound. Shooting sound through a liquid with a bubble in it will make the bubble pulsate and strongly scatter the sound.

Research into the potential of bubble acoustics has taken many different directions under the leadership of Professor Timothy Leighton from the University’s Institute of Sound and Vibration Research. Inspired by the way dolphins hunt using bubble nets, Timothy and his colleague Professor Paul White developed the world’s only sonar capable of detecting mines in bubbly seawater (TWIPS - Twin Inverted Pulse Sonar). They then translated the technology from acoustics to radar, devising Twin Inverted Pulse Radar (TWIPR), which was subsequently built in collaboration with University College London. TWIPR is able to distinguish true ‘targets’, such as certain types of electronic circuits that may be used in explosive or espionage devices, from ‘clutter’ (other metallic items like pipes, drinks cans, nails for example) that may be mistaken for a genuine target by traditional radar and metal detectors.

Timothy says: “When I saw dolphins blowing bubble nets to herd fish in order to hunt them, I knew they must be doing something special, because the best manmade sonar would not have been able to distinguish the fish from the bubbles. The dolphins would not be deliberately blinding their best sensory apparatus – their sonar – when hunting. So I devised the use of Twin Pulses to find the target of interest against a background of clutter, which works for finding fish or mines in bubbly coastal seawater, so that in the aftermath of conflict we could make relief efforts, trade and recreation safe. But even as I devised TWIPS, I knew that the equations I was writing about sonar could equally apply to radar to make minefields safe and find improvised explosive devices.”

Their bubble acoustics research has also been used to monitor leaks from undersea oil and gas pipelines (with devices planned for the North Sea seabed in 2018), to assess the amount of methane in the seabed (important for climate change modelling) and in devices to monitor tumour therapy. Other developments include needle-free injectors for migraine sufferers (of which more than a million have been sold) and new sensors to monitor the efficiency of kidney stone treatment. The biggest impact of bubble acoustics has been the contributions to the guidelines under which fetal ultrasonic scanning takes place, contributing to over two billion births since 1998. Timothy says, “I was humbled and honoured to be a co-author on the 1998 report by the World Federation for Ultrasound in Medicine and Biology that distilled down all the discussions on safety that we had had in Japan and Germany – it was a huge experience to work in a multidisciplinary team of such high quality.”

Cleaning revolution

Further research has centred around a pioneering collaboration between Timothy and Dr Peter Birkin from Chemistry, resulting in the development of a revolutionary new cleaning system. The system uses ultrasound and tiny bubbles to dramatically improve the cleaning power of cold water. The ultrasonic ‘StarStream’ technology, which can clean without the need for heat or additives, is particularly effective at cleaning out grooves and cracks in surfaces, areas that are difficult to reach by conventional cleaning methods.

This ground-breaking technology has attracted attention for some time. In 2011 StarStream received the £250,000 Royal Society Brian Mercer Award for Innovation. It also received the 2012 Institute of Chemical Engineering Award for Water Management and Supply, and in 2014 added the Best New Product of the Year award from S-lab (Safe, Successful and Sustainable Laboratories).

Through a link up with a company that already specialises in ultrasonic cleaning, the technology has been taken further; Ultrawave Ltd in Cardiff is collaborating with Timothy to discover how it can be used practically in the medical, pharmaceutical, aerospace, automotive and manufacturing industries.

Diverse benefits

Prototype StarStream devices have been proven to be effective cleaners for biomedical problems in collaborations with several leading academics in different fields at Southampton. They include Professor Bill Keevil, who is interested in the removal of bacteria, viruses and fungi in medical settings, Professor Richard Oreffo, who leads the Bone and Joint Research Group based at the Institute of Developmental Science, and Dr Paul Stoodley who researches dental plaque biofilms. The new Enterprise Units, NC2, collaborated with Timothy to prove how well StarStream removes from railway lines the slippery leaf residue crushed onto tracks by train wheels, responsible for the £50m ‘leaves on the line’ loss to the network each year.

StarStream could also allow more efficient cleaning of endoscopes and other surgical tools, as John Melville, Managing Director of Ultrawave Ltd explains:

“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, whilst reducing opportunities for human error by removing the number of stages an item has to go through before it reaches a 100 percent kill rate.”

Having run through a series of robust tests on earlier prototypes, Ultrawave is getting ready to launch its first “for sale” device to the industrial market. In the meantime, a range of industry users have begun funding research, from cleaning food to teeth, following publication of scientific studies proving StarStream’s effectiveness at cleaning in biomedical scenarios (cleaning blood, biofilms of teeth, bone prior to transplant, cleaning brain tissue of surgical instruments, hand cleaning), plus effective cleaning in scenarios away from the healthcare sector, such as removing marine foulant from ship hull material, and cleaning railway lines.

The advances in cold water cleaning have continued with the invention of an ultrasonic device for cleaning flat surfaces such as floors, tables etc., with trials taking the invention into hospitals and food preparation areas. Discussions are underway with a manufacturer.

Game-changers

By revolutionising cleaning, StarStream has huge potential in the battle against antimicrobial resistance (AMR) – the increasing resistance that microbes display to countermeasures like antibiotics. Timothy has founded NAMRIP (the Network for AntiMicrobial Resistance and Infection Prevention), a University Strategic Research Group in which 170 members across seven Faculties work together to produce new solutions to AMR. One project Tim wants to try in NAMRIP is ultrasonic hand cleaning, because high standards of cleanliness are crucial for containing the spread of infections. “We know that we should wash our hands for 20 seconds in warm soapy water, yet despite this knowledge, most people wash them for around six seconds in cold water,” says Tim. “If you can’t change behaviour, change the water. I want to incorporate ultrasonics into taps and faucets to make cold water clean as effectively as warm soapy water – in that six seconds,” he continues.

“There has been a lot of talk about making funding available to develop new antibiotics, but NAMRIP offers a wide range alternative approach to bringing antimicrobial resistance under control,” continues Timothy. “If you need to give someone an antibiotic, there must have been a failure in infection prevention or vaccination, and in NAMRIP we aim to prevent such failure. If you want to make a difference with infection prevention, it is important to take risks and try game-changers, like StarStream,” concludes Timothy.

Whether in revolutionary cleaning systems or monitoring underwater oil leakage, bubble science is a pioneering and exciting area of research, in itself a game-changer.

In one year NAMRIP (the Network for AntiMicrobial Resistance and Infection Prevention) has gone from an initial £10k startup funding as a University Strategic Research Group (plus the immeasurable value of Frances Clarke’s admin support) to see its members win £1M network funding, £6M in specific research projects, and now contribute significantly to the University winning a £15M BRC bid. Moreover we have engaged with industry and other partners to the extent that we have won 8 PhD studentships without relying on University income, (mainly with industry support, indicative of our drive in translating fundamental research through to benefits for society). NAMRIP has attracted praise from Chief Medical Officer, Sally Davies.

The history of our first year is clear from our News page. It is great to finish the year with this BRC win for Southampton to see such a stunning collaboration between the University and the Hospitals, to undertake exactly the translation NAMRIP was designed to do.’

‘We appreciate our income, but we value our efficiency (the ratio of outputs to the income we receive), and to keep our efficiency high we know that income wins like this must drive us to make a real practical difference to societal problems from our fundamental research. The strength of NAMRIP is in the outputs that power up the top of the efficiency fraction. We have brought together engineers, chemists, microbiologists, environmental scientists, veterinary and human medics, clinicians who contribute to international and national antibiotic guidelines for specified conditions, experts in food, ethics and law, crucially networked with economists, geographers, health scientists and experts from other social science disciplines to provide a truly joined up approach to AMR and Infection Prevention (offsetting the loss of diversity in pharmaceutical industry research teams).

Whilst our members have produced almost weekly journal publications and formed exciting new research collaborations, we have changed the world outside of academia, engaging with the public, and we have now begun translating our inventions into the wider world, with the first of our inventions tested in hospitals across the UK. In this first year we have hosted two fantastic conferences plus a pan-UK AMR leaders meeting, seen our members win numerous prizes and awards, and my favourite web page is our news page, with almost weekly developments. We have ended the first year with the launch of Global-NAMRIP (to work with low/middle income countries in tackling AMR and find effective interventions supporting vaccination and infection prevention) and now top our first 12 months with this BRC win.’

 

 

 

More information on Timothy's research

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