Nature's pipettes

22 November 2010

A pipetting method that mimics the way flowers protect themselves from water damage could find its way into restaurants, say US and French scientists.

Flowers in aquatic environments have a flood defence mechanism. When they are submerged in water, the petals fold over to form a capsule, trapping an air bubble within, protecting the genetic material. Pedro Reis and his colleagues at the Massachusetts Institute of Technology, Virginia Tech and Paris Tech recreated this phenomenon using a petal-shaped vinylpolysiloxane film that they cast and cut to achieve the required stiffness.

The team found that when the film was pulled out of water, it closed up to grab between 20 and 600 mm3 of water. The petals were then prevented from opening, much like how water will not flow from the open end of a straw if the other end is covered. They realised that the pipetting mechanism effect is mathematically opposite to that of the flower trapping an air bubble. 'It is the inverse of the natural problem only in that the hydrostatic pressure, resulting from gravity, is a source of suction that causes closure when the flower is pulled upwards,' explains Reis' colleague John Bush, who adds that the same phenomenon would occur in real flowers were it not for the stalk obstructing the closure.

Chef José Andrés is looking to use this phenomenon to introduce a new palate cleanser between courses

Bush is collaborating with chef José Andrés, who trained at the three Michelin-starred restaurant El Bulli in Spain and now owns a number of restaurants in Washington DC, US. Andrés is looking to use this phenomenon to introduce a new palate cleanser between courses. 'You could make the flower edible, perhaps out of gelatine,' explains Reis, 'and inside would be strong liquor. You could eat the whole thing.'

'I think it's nice in the sense that it's passive,' says Dominic Vella, an expert in fluid mechanics at the University of Cambridge, UK. 'All you have to do is touch the pipette down and then lift it up and it automatically captures a volume.'

Reis and his team are now looking to explore further uses for their pipettes, including using them to grab oil that's floating on water.

Yuandi Li


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