Coatings with controlled porosity and chemical properties

A coating for providing both size selectivity and chemical selectivity among different chemical species, the chemical species comprising analyte species of larger size and analyte species of smaller size, the analyte species of smaller size comprising analyte species having either a predetermined chemical reactivity or a predetermined chemical non-reactivity, said coating comprising:

• one or more layers comprising size selectivity means followed by chemical selectivity means wherein said chemical selectivity of the analyte species occurs only after said size selectivity of the analyte species;
• wherein the layer which comprises said size selectivity means comprises pores having a predetermined uniform pore size, said predetermined uniform pore size sufficient to prevent the analyte species of larger size than said pores from entering said pores and said predetermined uniform pore size sufficient to allow the analyte species of smaller size than said pores to enter said pores;
• wherein the layer which comprises said chemical selectivity means comprises chemical reaction sites for chemically sorbing the analyte species of smaller size with the predetermined chemical reactivity entering said pores and not chemically sorbing the other analyte species of smaller size with the predetermined chemical non-reactivity entering said pores;
• wherein said coating provides selectivity of the analyte species of smaller size having the predetermined chemical reactivity from the analyte species of larger size and from the analyte species of smaller size having the predetermined chemical non-reactivity;
• and
• wherein said chemical reaction sites comprise a metal as chemically reactive species.

A selective chemical sensor comprising a coating disposed on a sensor substrate, said coating providing for both size selectivity and chemical selectivity among different chemical species, the chemical species comprising analyte species of larger size and analyte species of smaller size, the analyte species of smaller size comprising analyte species having either a predetermined chemical reactivity or a predetermined chemical non-reactivity, said coating comprising:

• one or more layers comprising size selectivity means followed by chemical selectivity means wherein said chemical selectivity of the analyte species occurs only after said size selectivity of the analyte species;
• wherein the layer which comprises said size selectivity means comprises pores having a predetermined uniform pore size, said predetermined uniform pore size sufficient to prevent the analyte species of larger size than said pores from entering said pores and said predetermined uniform pore size sufficient to allow the analyte species of smaller size than said pores to enter said pores;
• wherein the layer which comprises said chemical selectivity means comprises chemical reaction sites for chemically sorbing the analyte species of smaller size with the predetermined chemical reactivity entering said pores and not chemically sorbing the other analyte species of smaller size with the predetermined chemical non-reactivity entering said pores;
• wherein said coating provides selectivity of the analyte species of smaller size having the predetermined chemical reactivity from the analyte species of larger size and from the analyte species of smaller size having the predetermined chemical non-reactivity and wherein said substrate comprises a piezoelectric substrate capable of detecting mass changes resulting from sorption of material thereon.