IBM tantalized chip aficionados at CeBit with a storage device that it says can achieve data densities of more than 1 terabit per square inch. The MEMS prototype can hold the equivalent of 25 DVDs on an area the size of a postage stamp, IBM said. MEMS stands for micro-electrical-mechanical system. IBM researchers in Zurich, Switzerland, have affectionately named the device the Millipede because it has thousands of very fine silicon tips that can “punch” individual bit patterns onto a thin film of polymer. The Millipede uses the tips to create pits, or bit patterns, approximately 10 nanometers wide to represent the stored data. IBM says that the principle is similar to the older technology of data punch cards, but the Millipede can also erase and rewrite data.