Caffeine-imprinted conducting polymeric films with 2D hierarchical pore arrays prepared via colloidal mask-assisted electrochemical polymerization

We developed novel caffeine-imprinted conducting polymer sensors with 2D hierarchical pore arrays. Colloidal mask-assisted electrochemical polymerization was used to design the molecularly imprinted conducting polymers (MICPs). First, 2D MICP micropore arrays were obtained by electropolymerization on 2D polystyrene (PS) colloidal arrays (d = 1 μm) fabricated via colloidal lithography. As a second step, each of two smaller PS colloids (d = 200 and 500 nm) was aligned onto the MICP pores, and second step electropolymerization was performed to fabricate hierarchical pore arrays. Relative to the single MICP pore array (MICP1) film, the two designed MICP films (MICP1-200 and MICP1-500) showed highly enhanced sensing properties such as sensing capacity, sensitivity, and selectivity. MICP1-200 film with nanoscale porous MICP network formed in each micropore exhibited significantly improved sensing behaviors, superior to MICP1-500 film. This sensing improvement is attributed to well-controlled MICP pore structures increasing the recognition cavities during surface imprinting. Thus, this novel strategy can be extensively used for the development of various MICP-based sensors.