A flexible perforated microelectrode array for extended neural recordings

A flexible and perforated 32-element planar microelectrode array has been fabricated and used to measure evoked potentials in brain slices. Electrodes are spaced 200 mu m apart in a 4*8 array and are sandwiched between layers of insulating polyimide. The polyimide sandwich is lifted off its substrate, making it flexible so that it could be shaped to contoured tissues. Prior to liftoff, holes are etched to expose recording sites 15 mu m in diameter and to create perforations which allow increased circulation of artificial cerebrospinal fluid to the recording surface of the tissue and, hence, increased viability. Comparisons of evoked potentials measured over tie showed an average increase of 10 h to the viability of the slice while using the perforated versus nonperforated arrays.