Chemical computers solve shapely puzzles

Computers these days take many different forms - desktops,laptops, tablets and smartphones-but all are based on shunting electrons through silicon. That's far tooordinary for Andrew Adamatzky,professor of unconventional computing at the University of West England,Bristol, who's attempting tobuild computers based on chemical reactions. Mixtures of certain chemicals form what's known as a Belousov- Zhabotinsky(BZ) reaction, which send out self-perpetuating waves that can be used tobuild logic gates and perform rudimentary computation. "Whenwaves collide they can either die or change direction, and we can interpretthis as computation," explainsAdamatsky. It's not an entirely new idea (see our feature on the "glooper computer") butnow Adamatzky and colleagueshave discovered that chemical computers can solve certain problems in computational geometry. These new computers are collections of smallchemical pouches called vesicles that can produce and combine BZ reactionwaves. A previous attempt used a hexagonal grid of vesicles but such aregular arrangement is difficult to build,so Adamatzky and colleagues wondered whether irregular vesicles could alsobe used for computation.They found that a vesicle computer could calculate the Voronoi diagram of a set oftwo-dimensional shapes - a taskwhich essentially involves working out which points on a flat sheet are closestto a particular shape. That might sound fairly arbitrary, but Voronoi diagrams have a wide range of applications, such as mapping the coverage of a network of mobile phone masts. They also used a vesicle computer tosolve a related problem, finding the topological skeleton of a shape. The results in this paper were actually simulated on a traditional computer, butAdamatzky says his team is now preparing another paper that details the sameresults achieved with real-world chemicals. The work is part of a wider effort toproduce chemical computers, which Adamatzky says could have a range ofapplications. "We could build computers that could be embedded in the humanbody," he says.