Scientists in the US have uncovered the inside story of solitons, the charge carriers active in certain conducting polymers. The newly discovered intricate internal structure of solitons could one day be exploited in molecular electronics and materials that work like artificial muscles, according to Ju Li of Ohio State University. Li and his colleagues at MIT have found that the electron within a soliton can have different energy states, analogous to the energy states in a hydrogen atom for instance. "While we know that such internal electronic structures exist in all atoms, this is the first time anyone has shown that such structures exist in a soliton," Li explains. When solitons pass through polymers, the polymer chains change shape, which leads to the possibility of using them as actuators or artificial muscle tissues. This new discovery could allow scientists to find a way to control this polymeric twitching.