Controlled Patterning of Complex Resistance Gradients in Conducting Polymers with Bipolar Electrochemistry

Conducting polymers have gained considerable attention for the possible design of localized electroactive patterns for microelectronics. In this work, the authors take advantage of the properties of polypyrrole, in synergy with a wireless polarization, triggered by bipolar electrochemistry, to produce localized resistance gradient patterns. The physicochemical modification is caused by the reduction and overoxidation of polypyrrole, which produces highly resistive regions at different positions along the conducting substrate at predefined locations. Due to the outstanding flexibility of polypyrrole, U-, S-, and E-shaped bipolar electrodes can be formed for prove-of-concept experiments, and electrochemically modified in order to generate well-defined resistance gradients. Energy-dispersive X-ray spectroscopy analysis of the samples confirms the localized physicochemical modifications. This approach presents as main advantages the wireless nature of bipolar electrochemistry and the possible fine-tuning of the spatial distribution of the electrochemical modification, in comparison with more conventional patterning methods.