A flexible circuit electrode array with more than one layer of metal
traces comprising: a polymer base layer; more than one layer of metal
traces, separated by polymer layers, deposited on said polymer base
layer, including electrodes suitable to stimulate neural tissue; and a
polymer top layer deposited on said polymer base layer and said metal
traces. Polymer materials are useful as electrode array bodies for neural
stimulation. They are particularly useful for retinal stimulation to
create artificial vision, cochlear stimulation to create artificial
hearing, or cortical stimulation many purposes. The pressure applied
against the retina, or other neural tissue, by an electrode array is
critical. Too little pressure causes increased electrical resistance,
along with electric field dispersion. Too much pressure may block blood
flow.