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 o f local polymerization applied to polythiophene is developed and discussed. The monomer dissolved in the solution is polymerized onto an oxidizing man ganese dioxide surface, which is locally activated by tip-generated protons . An increase in resolution by a factor of 5 has been accomplished by the i ntroduction of a chemical lens. The addition of a scavenger that reacts wit h the protons produced a significant focusing effect on the proton's diffus ion field. Under these conditions, the resolution was achieved down to 8 mu m 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-surfac e distance, and scan rate on the structure's width. The patterns obtained w ere then successfully imaged by SECM and optical means.