Master electrode and method of forming it

A system comprising a master electrode arranged on a substrate,

• said master electrode comprising a pattern layer, at least partly of an insulating material and having a first surface provided with a plurality of cavities in which a conducting material is arranged, said electrode conducting material being electrically connected to at least one electrode current supply contact;
• said substrate comprising a top surface in contact with or arranged adjacent said first surface and having conducting material and/or structures of a conducting material arranged thereon, said substrate conducting material being electrically connected to at least one current supply contact;
• whereby a plurality of electrochemical cells are formed delimited by said cavities, said substrate conducting material and said electrode conducting material, said cells comprising an electrolyte;
• characterized in that
• an electrode resistance between said electrode conducting material and said electrode current supply contact and a substrate resistance between said substrate conducting material and said substrate current supply contact are adapted, such that a specific conductivity of the electrode conducting material in average is from 0.1 to 100 times a specific conductivity of the substrate conducting material.