Engineers learn from the beetles (9/20/2007)

Several species of bombardier beetles can blast potential predators with a hot spray of liquid created by the chemical reaction of mixing hydroquinone with hydrogen peroxide.

An amazing insect, which sprays its predators with toxic steam, has inspired research into a new generation of technology at the University of Leeds.

The research has resulted in the new µMist™ technology which has the potential to become the platform for the next generation of more effective and eco-friendly mist carrier systems. It has multiple potential applications – such as new nebulisers, needle-free injections, fire extinguishers and powerful fuel injection systems – all more efficient and environmentally-friendly than existing technologies.

The research funded initially by the Engineering and Physical Sciences Research Council, and subsequently by Swedish Biomimetics 3000 ®, enabled the Leeds team, led by Professor of Thermodynamics and Combustion Theory Andy McIntosh to examine the mechanisms at work in the bombardier beetle.

Just 2cm long, the beetle defends itself against all-comers – frogs, spiders, birds and insects – with a cocktail of steam and stinging chemicals which it can blast for distances of up to 20cm. The chemical and physical characteristics of the spray and the insect's physiology have been simulated using a scaled-up experimental rig in Prof McIntosh's laboratory at Leeds and built by Novid Beheshti and Andreas Prongidis with the expertise of skilled technician Steve Caddick. The rig uses heating and flash evaporation techniques to propel a variety of liquids and its 2cm chamber can blast the fluid for up to 4 metres.

A press day in the University of Leeds on Tuesday September 18 will give journalists the opportunity to see the technology at work and interview Prof McIntosh about the research.

The µMist™ spray technology enables droplet size, temperature and velocity to be closely controlled, allowing advancements in a variety of areas where the properties of the mist is critical. Such applications include fuel injection, medical drug delivery systems, fire extinguishers and fire suppression, all of which face major challenges relating to the demands of greater performance and reduced environmental impact.

Each of these sectors is actively seeking the next generation of mist systems. The dynamic electronic tuning capability of the mist's properties presents the a unique potential to sense the optimal mist characteristics required and then adjust accordingly, in real time. In areas such as soft mist inhalers and fire suppression, the new technology offers a major leap forward in performance.

In the medical field, the technology could provide a water-based carrier for propelling substances such as drugs, replacing conventional propellants which are potential pollutants. Used with fuels, this technology offers the potential to substantially increase fuel burning efficiency, improving fuel consumption and minimising exhaust pollution.

Prof McIntosh's research was inspired by entomologist Prof Tom Eisner of Cornell University who has worked for a number of years on the bombardier beetle. Ultra slow motion pictures shot by Eisner showed how the bombardier beetle expels fluid through a series of rapid pulses – the pressure in the insect's fluid chamber causing the liquid to be ejected, followed by a drop in pressure, which allows more fluid to enter and the pressure to build up once more.

Prof McIntosh likens the beetle's defence mechanism to a pressure cooker controlled by a complicated system of valves: "Essentially it's a high-force steam cavitation explosion. Using a chamber less than one millimetre long, this amazing creature has the ability to change the rapidity of what comes out, its direction and its consistency.

"Nobody had studied the beetle from a physics and engineering perspective as we did – and we didn't appreciate how much we would learn from it."

Further information:

Swedish Biomimetics 3000® Ltd has signed a worldwide exclusive licensing agreement for the development and commercialisation of the µMist™ technology. Potential application opportunities arising from the work have been filed for intellectual property rights.

Swedish Biomimetics 3000® Ltd is a V2PIO [virtual venture philanthropic intersectional organization] which funds translational research of biomimetics concepts to the point where they are commercially viable, when corporate partners are sought for the technology's further development. It was founded 2004 in Sweden and has established an affiliated company in the UK. Swedish Biomimetics 3000® Ltd programs are supported by leading edge organisations including Quintiles Consulting Europe.

The University of Leeds is acclaimed for the quality of its teaching and research. One of the largest universities in the UK, Leeds is also the most popular among students applying for undergraduate courses. An emphasis on innovative research and investment in high-quality facilities and first-rate infrastructure means that no fewer than 35 departments are rated internationally or nationally 'excellent'.

The Engineering and Physical Sciences Research Council (EPSRC) is the UK's main agency for funding research in engineering and the physical sciences. EPSRC invests more than Ł500 million a year in research and postgraduate training to help the nation handle the next generation of technological change. The areas covered range from information technology to structural engineering, and from mathematics to materials science. This research forms the basis for future economic development in the UK and improvements in everyone's health, lifestyle and culture. For more information visit www.epsrc.ac.uk

There are 500 species of bombardier beetle, mostly found in hotter areas of the world – Africa, Asia and South America – though there are some small colonies in the UK. Their tiny fluid chambers typically react hydroquinone with hydrogen peroxide to produce a fiery blast of steam, though different species use slightly different combinations of exhaust nozzle arrangements.

Note: This story has been adapted from a news release issued by the University of Leeds

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