Abstract: The invention relates to a process for manufacturing a REFET and/or CHEMFET, comprising: (a) covalent bonding of a hydrophilic polymer layer to an isolator layer applied to a semiconductor material; (b) the absorption of water or a watery solution into said hydrophilic polymer layer; and (c) the binding of a hydrophobic polymer layer to the water holding hydrophilic polymer layer. It is advantageous that this water holding hydrophilic polymer layer also contains an electrolyte and/or a buffer.Preferably an ion to be measured with the CHEMFET also forms part of the electrolyte.