Generation of polythiophene micropatterns by scanning electrochemical microscopy

The use of the scanning electrochemical microscope (SECM) is shown to be an effective tool for microdeposition of conducting polymers. A new concept of local polymerization applied to polythiophene is developed and discussed. The monomer dissolved in the solution is polymerized onto an oxidizing manganese dioxide surface, which is locally activated by tip-generated protons. An increase in resolution by a factor of 5 has been accomplished by the introduction of a chemical lens. The addition of a scavenger that reacts with the protons produced a significant focusing effect on the proton's diffusion field. Under these conditions, the resolution was achieved down to 8 mum with a 10-mum Pt electrode: the pattern was smaller than the tool used to generate it. We studied the effects of scavenger concentration, tip-surface distance, and scan rate on the structure's width. The patterns obtained were then successfully imaged by SECM and optical means.