A microelectrode array having one or more electrical conduits surrounded and insulated from each other by only a single layer of polymer (e.g. polyimide), and a method of fabricating the same. Multiple layers of an uncured polymer precursor (such as polyamic acid) are separately formed with metal layers sandwiched in between. Formation of the uncured polymer precursor layers includes deposition and heating to remove solvent only but not polymerize the precursor. Upon completing construction, the array is subjected to a high-temperature curing process that converts the uncured polymer precursor layers into the polymer. The different layers of the polymer precursor are thus covalently bonded together during the curing process to create a single continuous layer (e.g. monolithic block) of polymer, with no polymer-polymer interfaces.
FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
 The United States Government has rights in this invention pursuant to Contract No. DE-AC52-07NA27344 between the United States Department of Energy and Lawrence Livermore National Security, LLC for the operation of Lawrence Livermore National Laboratory.