Abstract: A process for obtaining a multifunctional, ion-selective-membrane sensor is disclosed, which process comprises the following steps:a) preparation of a siloxanic prepolymer, followed by one or more deposition(s) of said siloxanic prepolymer on a device of MOS or ISFET type;b) preparation of a solution containing an ionophore, a monomer of a polymerisable olefin, 2,4-toluenediisocyanate and a dialcohol or a diamine or a glycol or a trialcohol or a triamine, which preparation is followed, after that said solution has been kept stirred for at least 48 hours at room temperature, by the deposition thereof on the siloxanic prepolymer, which deposition is carried out by means of a spinner;c) photochemical treatment in the presence of a photoinitiator by means of UV light, with a suitable mask being used, which allows the exposure to UV light to take place on one gate only;d) chemical washing of the sensor, by means of an organic solvent;e) thermal treatment ("thermal curing"), so as to complete the reactions of polym

Abstract: An ion sensor is disclosed, together with the relevant process for preparing it, which contains a polymeric organic matrix, a ionophore, a device based on semiconductors of EMOS or ISFET (CHEMFET) type containing at its surface silicon oxide adhering to said polymeric organic matrix by means of a polysiloxanic matrix, characterized in that the polysiloxanic matrix is selected from the organosilanes of general formula ##STR1## wherein: R.sup.II, R.sup.III, R.sup.IV, which may be either equal to, or different from, one another, are alkyl or alkoxy groups containing from 1 to 10 carbon atoms,R.sup.I is equal to (CH.sub.2).sub.p X (CH.sub.2).sub.q wherein:X is CH.sub.2, or an either mono- or polycondensed aromatic group, or NH or O,p and g, which may be either equal to, or different from, one another, are integers which can have values comprised within the range of from 0 to 10, with value 0 being excluded when X is either NH or O,Y is --NH.sub.