Porphyrin-Based Nano Switch (image) Technische Universitaet Muenchen Caption Physicists at the Technische Universitaet Muenchen have created a nano switch based on a single porphyrin ring. If one of two protons from the inside of the ring is removed, the remaining proton can take on any one of four positions, initiated by a single tunnel electron from the tip of a scanning tunneling microscope. Credit Knud Seufert / Technische Universitaet Muenchen Usage Restrictions None Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.