Novel technological process to manufacture ceramic microelectrodes for biomedical applications implying microextrusion of preceramic precursors

A novel technological process is under development to obtain ceramic microelectrodes from preceramic precursors, basically for biomedical applications. A microextrusion approach is applied. Commercially available silicone resins are used as preceramic polymers. Drugging with carbon black results in electrically conductive ceramics. A coextrusion approach is used to obtain the filament with inner conductive lines. Chemical reticulation and pyrolysis are applied to convert polymeric resins into ceramics. Some different geometries of profiles and cross sections can be considered and obtained. Circular microelectrodes can be provided with diameters in the range between 100 /spl mu/m and 5 mm and wide coextrusion dimension ratios are obtainable. Preliminary results on filaments with diameter between 100 /spl mu/m and 500 /spl mu/m showed bending strength ranging from 30 MPa to 1100 MPa and average conductivity of 0.375 1//spl Omega/cm for a 50% weight carbon black load. Selecting such characteristics and related materials mainly depends on specific applications. Biomedical electrodes can be devised as stimulators or sensors in neurosurgery, beep brain stimulation and cell biology. It's important to achieve strict control of the above characteristics demanded by desired performances and obtained by suitably adjusting the technological process. Such control is hard to attain for great sensitiveness of some features of micro-geometry and micro-structure to process parameters.