DUAL-CYLINDER MICROELECTRODES .2. STEADY-STATE GENERATOR AND COLLECTOR ELECTRODE CURRENTS

The feedback and collection diffusion current properties of platinum d ual-cylinder microelectrodes have been investigated using bipotentiost atic chronoamperometry. The study focuses on the influence of the inte relectrode spacing on the steady-state response at independently contr olled 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 mum platinum wire wit h gap spacings from 3.5 to 188 mum and cylinder lengths 250-500 mum. R ecycling efficiencies, expressed as an i(c)/i(g) ratio, observed with these feedback dual-microelectrodes could be as high as 83% for closel y spaced microcylinders. Electrochemical measurements further indicate that a convergence of the generator and collector currents would foll ow as the interelectrode distance diminishes below the mum 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 amperomet ric device is discussed with reference to the relevant theoretical sta tionary flux model proposed for dual-cylinder microelectrodes.