ABSTRACT
One component attributed to the sustained cellular response to implantation
is the chronic device-tissue interaction [1] that results from the motion of rigid
microelectrodes implanted in brain tissue with respect to the skull [2, 3]. The
global motion of the brain within the cranium induces local tissue damage
around implants. In order to decrease this response, flexible probes have been
designed by several groups to better adapt to brain-tissue motion. Polyimide
probes [4, 5] and parylene probes [6] have been developed in order to decrease
the mismatch in brain-device compliance. Flexible microelectrode arrays offer
the advantage of reducing damage after implantation because these devices can
move with the tissue. If the stiffness of device is optimized, the array is also
stiff enough for insertion into the brain. Therefore, arrays must be rigid
enough for insertion, but soft enough for movement once implanted. However,
while this represents an improvement in device stiffness, the surface of the
polymer material remains much stiffer than the brain tissue.
