Sorting out the good vibrations

| Cleanrooms and Contamination Control

Startstream water cavitation system

Andy Pye looks at two innovations which highlight how ultrasound can be used for the benefit of mankind, but also to its detriment.

Cleaning instruments between patients is critical to avoid transmission of agents leading to conditions such as Creutzfeldt-Jakob Disease. Now, researchers from the University of Southampton have demonstrated how a pioneering ultrasonic device can significantly improve cleaning of medical instruments and reduce contamination and risk of infection. The team that conducted the study now forms the basis of the University’s Network for Anti-Microbial Resistance and Infection Prevention (NAMRIP) Strategic Research Group, which hosts over 100 members under the chairmanship of Principal Investigator Professor Tim Leighton, from the University’s Institute of Sound and Vibration Research.

Good vibrations

StarStream, invented and patented by the University of Southampton and in commercial production by Ultrawave, makes water more efficient for cleaning by creating tiny bubbles which automatically scrub surfaces. The device supplies a gentle stream of water through a nozzle that generates ultrasound and bubbles, which dramatically improve the cleaning power of water reducing the need for additives and heating.

Using just cold water, StarStream is able to remove biological contamination, including brain tissue from surgical steel. It is also able to remove bacterial biofilms that typically cause dental disease and is effective at removing soft tissue from bones, which is required prior to transplants to prevent rejection of the transplanted material by the recipient’s immune system.

“In the absence of sufficient cleaning of medical instruments, contamination and infection can result in serious consequences for the health sector and remains a significant challenge. Our highly-effective cleaning device, achieved with cold water and without the need for chemical additives or the high power consumption associated with conventional strategies, has the potential to meet this challenge and transform the sector,” says Leighton. “We are very grateful to the Royal Society Brian Mercer Fund for giving us the opportunity to use fundamental research to prove the effectiveness of StarStream, whilst at the same time exploring ways to commercialise it. Commercialisation is vital: if we cannot build a business that can sell thousands of these to health providers at a price they find attractive, this invention will stay in the laboratory and help no-one.”

Bad vibrations

Meanwhile, other research from the University of Southampton indicates that the public are being exposed, without their knowledge, to airborne ultrasound. The study has found increasing exposure to ultrasound in locations such as railway stations, museums, libraries, schools and sports stadiums, in which there have been complaints of nausea, dizziness, migraine, fatigue and tinnitus.

Ultrasound in public places can be generated from a number of sources, including loudspeakers, door sensors and public address systems. For a number of years, workers who have been regularly exposed to occupational ultrasound through industrial devices for cleaning and drilling have reported similar negative effects.

While there has been insufficient research to confirm or deny a link, Leighton tells us that current guidelines and research knowledge for occupational safe levels are inadequate to cope with the current mass exposure of large numbers of people. “Existing guidelines are insufficient for such large public exposures as the vast majority refer to occupational exposure, where workers are aware of the exposure, can be monitored and can wear protection. Furthermore, the guidelines are based on the average response of small group, often of adult males,” he says. “The guidelines are also based on an insufficient evidence base, most of which was collected over 40 years ago by researchers who considered it insufficient to finalise guidelines, but which produced preliminary guidelines. This warning of inadequacy was lost as regulatory bodies and organisations issued ‘new’ guidelines based on these early guidelines, and through such repetition generated a false impression of consensus.”

Using smart phones and tablets equipped with an app that produced a spectrogram of the microphone reading, Leighton collected readings of very high frequency/ultrasonic fields (VHF/US) fields in a number of public buildings, at a time when they were occupied by hundreds of people. The findings were then calibrated with two or three independent microphone and audio data systems.

Leighton has found that members of the public were exposed to VHF/US levels over 20kHz, which is the threshold of the current guidelines. He is now calling for further research and the production of a new set of guidelines based on this research. “Individuals who are unlikely to be aware of such exposures are complaining, for themselves and their children, of a number of negative conditions. Recent data suggests that one in 20 people aged 40-49 years have hearing thresholds that are at least 20 decibels (dB) more sensitive at 20kHz than that of the average 30-39 year old. Moreover, 5% of the 5 to 19 year age group is reported to have a 20kHz threshold that is 60dB more sensitive than the median for the 30-39 year age group,” he adds. “The lack of research means that it is not possible to prove or disprove the public health risk or discomfort. However, it is important that sufferers are able to identify the true cause of their symptoms, whether they result from VHF/US exposure or not.”

Keeping ultrasound under control?

Proposed Guidelines suggested by Professor Leighton of the University of Southampton Institute of Sound and Vibration Research

* No new guidelines must be based primarily on selection of levels quoted in older guidelines.
* Guidelines for occupational exposure must not be applied to public or residential exposure, and recognition must be given to exposure of long-term ‘guests’ (in schools, hospitals, prisons, public transport for example).
* Studies and new guidelines must take account of the deviation from the average of individuals within a population, and within particular demographic subsets within the population.
* Research is required to ensure that guidelines properly account for the selection of those adverse effects that should be minimised or prevented.
* Research must be undertaken to assess whether current audiological practices, equipment and standards are suitable for the VHF and ultrasonic regimes, and identify measures to rectify any shortcomings.
* A current survey of modern devices and their source levels (using international standard procedures and calibrations traceable back to primary standards) should be undertaken.

Non-invasive early cancer detection in under an hour

A Spanish university spin-off, AWSensors, is coordinating the European project LIQBIOPSENS to develop liquid biopsy technologies for the early detection of colorectal cancer, is the second cause of death in Europe and one of the most common, alongside breast, lung and prostate cancers. The new system will allow quick and easy cancer detection and monitoring at a third of the cost of the existing procedures, such as tumour tissue biopsy, which is invasive, painful and expensive, as well providing information at only a single point in the evolution of the disease. In contrast, liquid biopsy is only around a third the cost of other real-time methods, such as quantitative PCR, and it can be carried out by non-specialists.

This high-sensitivity molecular detection system is based on the analysis of small fluid samples, like blood or saliva, making it completely non-invasive. It is also fast, giving results within the hour. When combined with genomic analysis, it will be possible to obtain reliable early diagnoses and devise precision medicine approaches to cancer treatment.

The new detection system incorporates quartz microsensor technology patented by the Universitat Politècnica de València (UPV) that allows real-time analysis, combined with technology that can reliably detect DNA mutations, developed by Destina Genomics. By detecting both the DNA released by the tumour into the body and any cancer-associated mutations it undergoes, it will reliably detect the presence and evolution of this cancer, doing away with false positives.

Crystal quartz is often used in radars, mobile phones and watches. AWSensors has managed to get sensors made from this crystal to work high frequencies, harnessing its vibrations to detect molecular changes in different liquids and materials. Working at high frequencies boosts detection sensitivity. Not only can AWSensors’ system measure mass, but it can also provide information on other structural properties, like the thickness and viscoelasticity of the substance being analysed.

To take this technology further and test it on the blood samples of colorectal cancer patients over the next three years, AWSensors has secured funding from the European Commission.

Latest posts by Andy Pye (see all)

About Andy Pye

Andy Pye is a graduate of Cambridge University and has had a high profile career in the technical press as well as being a pioneer in web publishing.

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