FREQUENCY-DEPENDENT CAPACITANCE OF MICROELECTRODE ARRAYS AND CHARACTERIZATION OF THE METAL-POLYMER INTERFACE

The seal between the metal and Tefzel in microband electrodes and arra ys is described. The high apparent capacitance of these electrodes sug gests that the solution penetrates between the metal and Tefzel. The s olution penetrates most deeply into platinum electrodes, while gold an d nickel electrodes have relatively good seals. The depth of penetrati on for platinum electrodes is estimated from capacitance data to be as large as 1.2 mm; however, the gap depth is highly variable. By coulom etry of a ferricyanide solution contained in the gaps, the gap width i s estimated as 1-2 mum. Platinum electrodes with an excellent seal to Tefzel can be prepared if the platinum foil is sputter coated with a t hin layer of gold before the electrode is constructed.