Microfabricated, Massive Electrochemical Arrays of Uniform Ultramicroelectrodes

We report the preparation and electrochemical characterization of massive electrochemical arrays containing as many as 110,000 highly uniform ultramicroelectrodes (UMEs). These arrays were microfabricated using conventional photolithography techniques on a gold-coated silicon chip in a simple three-step method. Photoresist polymer was used as an effective insulating matrix to define 2 μm, 3 μm, and 4 μm diameter circular UMEs across a 1 × 1 mm² area. The UME arrays are high uniform and contain tens of thousands of active disk-shape UMEs slightly recessed in thin films of photoresist. These arrays were tested with cyclic voltammetry and copper electrodeposition to assess the adhesion of photoresist to the gold surface as well as to examine their electrochemical activity. Numerical simulations were performed to further validate their electrochemical response. These UME arrays can be a useful platform for fundamental understanding molecular transport in uniform electrochemical arrays and designing highly-sensitive electroanalytical sensors.