Buckling strength of coated and uncoated silicon microelectrodes

A penetrating microelectrode must be sufficiently strong to withstand the forces associated with inserting it into the brain without buckling or fracturing. If the insertion force exceeds the microprobe´s buckling strength, the probe will buckle along its shank. The objective of this study was to investigate the buckling strength of thin-film silicon microprobes that include a hollow microchannel along the penetrating shank. The experiments included uncoated, polymer filled, and polymer coated devices. The polymer-coated probes showed a 16% increase in buckling strength, while the polymer filled probes showed a 4% increase over control puffer probes. In both cases, the buckling strengths were 250 times greater than that required for probe implantation in human brains. Filling the microchannel with silicone resulted in a probe that was shatter resistant even under extreme loads. These results indicate that thin-film silicon microprobes can be designed to be suitable for diverse neurophysiological and neurosurgical applications.