The objective of the proposed research is to demonstrate the application of ultraviolet (UV) laser ablation technology as an improved alternate to either local heating, ac arcing or plasma etching in the selective removal of Parylene(R) from neurophysiological microelectrodes. In Phase I, feasibility of the laser ablation technique as well as its accuracy was successfully demonstrated and characterized. Electrical and mechanical evaluation showed improved performance over probes fabricated by existing methods. Also during Phase I, complete electrical facilities for testing and activation of iridium microelectrodes were developed. Although the main concentration of Phase I was on sharpened iridium wire probes, part of the work was devoted to multiple site planar probes furnished by the University of Michigan or created for Emory University. Phase II will focus on the information gleaned in the Phase I studies in order to configure and build a state-of-the-art UV laser system, and produce the best possible microelectrodes for long lived, stable, in vivo applications. These are not only to include sharpened wire electrodes but also multiple site electrodes as in the University of Michigan probes and in the stranded wire electrodes produced for Emory University. In Phase II an effort will be made to make these processes manufacturable which also entails the development of handling and shipping protocol to minimize impedance shifts after activation. PROPOSED COMMERCIAL APPLICATION: Because of the plethora of probe types this method addresses, it would have tremendous value in visual and cochlear protheses as well as a host of other applications such as sensing and nerve stimulation for muscle control, biosensing and in vivo monitoring. Dr. Gerald Loeb's group at Queen's University has demonstrated the greatest degree of confidence in the SBIR Phase I wire based electrodes as a viable visual prosthetic by implanting 32 of them in a human patient on May 30, 1994.