Solving mazes with glowing plasma

In 2002 Andreas Manz of Imperial College London and his collaborators demonstrated a novel way to solve mazes. First, they etched a maze pattern onto a microfluidic chip using laser lithography. Then they filled the device with low-pressure helium. To find the shortest path to the center of the maze, they attached electrodes to the entrance and center of the maze. Turning up the voltage to 20–30 kV triggered the abrupt formation of a glowing plasma discharge that picked out and lit up the shortest path. Now Alexander Dubinov of the Russian Federal Nuclear Center in Sarov and his collaborators have devised a way to make the maze-solving technique cheaper and potentially more practical. Manz’s original approach entailed etching a new chip for each maze pattern, which is time-consuming and expensive. The use of helium and high voltages also push up the cost. Dubinov’s mazes consist of polyamide walls sandwiched between plexiglass. They are filled with low-pressure air and operate at voltages of a few kilovolts. Thanks to the ease with which the walls can be reconfigured, Dubinov and his collaborators could readily investigate how the plasma solves the mazes. They discovered, for example, that when the shortest path includes sections that require electrons to move away from the anode, the voltage needed to solve the maze drops. With further development, the technique could enable robots to navigate mazes and solve other topological problems. (A. E. Dubinov et al., Phys. Plasmas 21, 093503, 2014, doi:10.1063/1.4894677 .)