Insect feet boost buoyancy work

The feet of pond skaters have helped create a novel super-buoyant material. Finnish scientists have drawn on the structure of the insect's foot to exploit its ability to let the creature skim across a pond's surface. The buoyancy of the material has been boosted by making it out of plant cellulose. The properties that make it float could help it act like a powerful sponge to aid oil spill clean-ups, say its creators. Five fridges The material is a type of aerogel - substances in which the liquid has been replaced with a gas but the structural components are left in place. The lightest aerogels are only a few times denser than air itself and have been called "solid smoke". The aerogel created by Dr Olli Ikkala and colleagues at the Helsinki University of Technology uses tiny fibres from plant cellulose - a natural polymer that, in some ways, resembles plastic. Cellulose is typically used to make paper and cloth. Dr Ikkala's team have used a specially processed form of cellulose, known as nanocellulose, to form their gel. "These materials have really spectacular properties that could be used in practical ways," said Dr Ikkala in a statement. Early tests based on a cellulose aerogel constructed to a design suggested by the feet of the pond skater have revealed how buoyant it is. They speculate that a 500g chunk of the material could support five standard household fridges weighing about half a tonne. The early work has also revealed that the material is a very efficient sponge that could aid oil spill clean-up efforts. Floating mats of the aerogel could be dragged through the water gathering up spilled oil which could then be recovered. The research was unveiled at the spring meeting of the American Chemical Society.