Abstract: The present invention relates to a method for selectively modifying electrodes of an array of electrodes. The array of electrodes may be used as a sensor or biosensor to determine the presence of and/or identity of each of a plurality of analyte molecules. In accordance with the present invention, electrodes of each of a number N subsets of electrodes of an array of electrodes are contacted with a respective liquid, each of which comprises a respective, different molecule. For each subset of the N subsets of electrodes, at least one of the member electrodes is deprotected to allow molecules of the respective liquid to associate with the deprotected electrode. The steps of contacting subsets of electrodes and deprotecting selected electrodes is repeated until each electrode in the array has been associated with a predetermined molecule.