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Page 2 of 2 1) The beetle uses it muscles to open the connecting vale, forcing chemicals into the reaction chamber. 2) The chemical reacts with the catalysts and the liquid chemicals in the reaction chamber and reaches a temperature of more than 105° C. 3) The release of gasses and the increase in temperature cause an increase in pressure. 4) When pressure reaches 1.1 bar the exit valve is forced open and the gasses rapidly expand. 5) This causes the connecting valve to close. 6) The pressure stays high until the end of the discharge, when the pressure rapidly drops. 7) This closes the exit valve and opens the connecting valve, thus continuing the cycle until the beetle relaxes its muscles. The researchers then built an experimental rig showing that the principles of the bombardier beetle can be recreated artificially. The rig uses heating and flash evaporation techniques to propel a variety of liquids. The small 2 cm chamber can squirt liquid up to 4 metres or produce a fine mist with droplets as small as 2 µm. The rig has been developed further into the µMist™ spray technology, which allows a very fine control of the droplet size, temperature and velocity of the spray by imitating the two-valve system of the beetle by using electronic controlled pressure valves. Applications include fuel injection, medical drug delivery and fire extinguishers.
 The bombardier beetle defending itself against an ant. Drawing courtesy of the EPSRC.
Literature Behesthi, N. and McIntosh, A., C. (2007) The bombardier beetle and its use of a pressure relief valve system to deliver a periodic pulsed spray. Bioinspiration & Biomimetics 2: 57-64. Beheshti N and McIntosh A., C. A bio-inspired mass ejection device using the micro explosive technology of the bombardier beetle Bioinspiration &. Biomimetics. In preparation Press release from EPSRC (Engineering and Physical Sciences Research Council, UK)
http://www.epsrc.ac.uk/PressReleases/BeetlesInspireNewGeneration.htm
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