Combined Electrochemical Surface Plasmon Resonance for Angle Spread Imaging of Multielement Electrode Arrays

A surface plasmon resonance imaging system combined with a multielement electrode array is described. An optical system with shaping optics is used to direct a wedge of light onto a gold-coated sample. The reflected light is detected in the form of an angle-spread image of the surface, with one direction denoting a variable incident angle and the other showing a span of locations along one lateral direction of the sample surface. At the proper incident angle, the angle-spread image shows the complete surface plasmon resonance curve over a span of locations on the surface. This imaging system is combined with a sample configuration consisting of a series of gold microelectrode bands, each with independent electrochemical control. In solution, this system can be used to perform high-throughput and dynamic electrochemical experiments. Simultaneous measurement of electrochemical and surface plasmon resonance can be quantitatively performed on each of the electrode surfaces either by holding each electrode at a different potential value or by scanning the applied potential. The sensitivity of this configuration is demonstrated by monitoring oxide formation and removal at a gold electrode in an aqueous electrolyte. A second example, with the use of a thin poly(aniline) coating, illustrates the ability to monitor film changes, including thickness, dielectric properties, and associated electrochemically induced polymer oxidation/reduction on multiple electrodes. This represents a simple and compact method for combining the sensitivity of surface plasmon resonance into an array-based, high-throughput electrochemical system.