improved low - cost , highly reliable methods for increasing the electrochemical surface area of neural electrodes are described . a mono - layer of polymeric nanospheres is first deposited on a metallization supported on a dielectric substrate . the nanospheres self - assemble into generally repeating lattice forms with interstitial space between them . then , the geometric surface area of the metallization material is increased by either selectively etching part - way into its depth at the interstitial space between adjacent nanospheres . another technique is to deposit addition metallization material into the interstitial space . the result is undulation surface features provided on the exposed surface of the metallization . this helps improve the electrochemical surface area when the treated metallizations are fabricated into electrodes .