Imaging electrochemical microprocesses on the surfaces of metallic biological materials: Studies utilizing the scanning electrochemical microscope

The electrochemical behavior of metallic biomaterials has, in the past, been examined by various in vitro electrochemical techniques which detect average rates of electrochemical activity across an entire metallic surface. These techniques provide no ability to image or characterize localized electrochemical events taking place on the metallic surface.; In the past decade many types of nonoptical scanning microscopic devices have become available with the result that many processes and structures that formerly could not be imaged are now routinely examined utilizing these techniques. These devices form images by scanning some type of microprobe device on or near the surface in question and changes occurring at the tip are recorded along with the x-y position of the microprobe. The three dimensional data obtained with these instruments can be plotted as a three dimensional surface.; The Scanning Electrochemical Microscope (SECM) is a environment and images interactions of charged ions with a solid state microprobe that is scanned very near a metallic sample surface. The ions are generated by electrochemical processes at the metallic surface while both the microprobe and sample are under bipotentiostatic voltage control. The SECM thus operates as a four electrode electrochemical cell with the metallic surface and microprobe acting as working electrodes (counter and reference electrodes are also present in the cell). The SECM senses Faradaic currents that pass through the microprobe and these currents are related to charge transfer controlled electrochemical processes taking place at the sample surface. The SECM is thus a powerful in vitro imaging method when used to monitor electrochemical microprocesses that take place at the interfacial region between metallic biomaterials and aqueous biological environments.; In this work, an SECM was constructed to operate at the surfaces of metallic biological materials which were immersed in a physiological saline environment. Images of highly localized charge transfer processes on these surfaces in an environment closely resembling that found in biological systems were obtained for several metallic biological materials.