A micromachined silicon depth probe for multichannel neural recording

A process of making a new type of silicon depth-probe microelectrode array is described using a combination of plasma and wet etch. The plasma etch, w hich is done using a low temperature oxide (LTO) mask, enables probe thickn ess to be controlled over a range from 5 to 90 mu. Bending tests show that the probe's mechanical strength depends largely on shank thickness. More fo rce can be applied to thicker shanks while thinner shanks are more flexible , One can then choose a thickness and corresponding mechanical strength usi ng the process developed. The entire probe shaping process is performed onl y at low temperature, and thus is consistent with the standard CMOS fabrica tion. Using the probe in recording from rat's somatosensory cortex, we obta ined four channel simultaneous recordings which showed clear independence a mong channels with a signal-to noise ratio performance comparable with that obtained using other devices.