Dual-cylinder microelectrodes Part 2.—Steady-state generator and collector electrode currents

Abstract

The feedback and collection diffusion current properties of platinum dual-cylinder microelectrodes have been investigated using bipotentiostatic chronoamperometry. The study focuses on the influence of the interelectrode spacing on the steady-state response at independently controlled generator and collector microcylinders. A series of such devices were fabricated onto polyethylene terephthalate (PET) strips using a microscope manipulation method. Micro-manipulation techniques allowed dual-cylinder devices to be constructed using 25 µm platinum wire with gap spacings from 3.5 to 188 µm and cylinder lengths 250–500 µm. Recycling efficiencies, expressed as an i_c/i_g ratio, observed with these feedback dual-microelectrodes could be as high as 83 % for closely spaced microcylinders. Electrochemical measurements further indicate that a convergence of the generator and collector currents would follow as the interelectrode distance diminishes below the µm scale where the strength of the recycling flux field at the device is high enough to minimise bulk solution exchange. The response of the new amperometric device is discussed with reference to the relevant theoretical stationary flux model proposed for dual-cylinder microelectrodes.