Surface type microelectronic gas and vapor sensor

In a microsensor structure comprising a substrate having a surface having an active area, first and second adjacent electrodes having, respectively, sensing and counter portions on the active area;

• and an electrolytic medium covering the active area, the improvement comprising:
• positioning the first and second electrodes sufficiently close together on said active area so that the time of migration of an ionic moiety from one to the other of the electrodes is no more than about 1 minute;
• restricting the thickness of the electrolytic medium to be no more than about 10 microns so that the time of diffusion of the gaseous species through the electrolytic medium to the first electrode is no more than about equal to the time of migration of the ionic moiety from one to the other of the electrodes;
• a barrier covering said electrolytic medium, said barrier being permeable to an analyte gas;
• and
• an aqueous reservoir internal of said substrate in flow communication with said electrolytic medium.

In a microsensor structure comprising a substrate having a surface having an active area, first and second adjacent electrodes having, respectively, sensing and counter portions on the active area;

• and an electrolytic medium covering the active area, the improvement comprising:
• positioning the first and second electrodes sufficiently close together on said active area so that the time of migration of an ionic moiety from one to the other of the electrodes is no more than about 1 minute;
• restricting the thickness of the electrolytic medium to be no more than about 10 microns so that the time of diffusion of the gaseous species through the electrolytic medium to the first electrode is no more than about equal to the time of migration of the ionic moiety from one to the other of the electrodes;
• a barrier covering said electrolytic medium, said barrier being permeable to an analyte gas;
• a third electrode having a reference portion in contact with said electrolytic medium and free from contact with said first and second electrodes;
• and
• an aqueous reservoir internal of said substrate in flow contact with said electrolytic medium.

A microsensor structure for sensing an analyte in a gas phase, comprising:

• a substrate having a surface having an active area;
• a sensing electrode having a sensing portion on said active area, said sensing portion comprising a plurality of sensing fingers and having an outfacing surface facing away from said substrate;
• a counter electrode having a counter portion on said active area, said counter portion comprising a plurality of counter fingers, said counter fingers being positioned between and aligned generally along said sensing fingers to define sensing finger-counter finger gaps of no more than about 50 microns;
• a reference electrode having a reference portion on said active area and being free from contact with said sensing and counter electrodes;
• an electrolytic medium on said active area bridging said sensing finger-counter finger gaps and communicating said reference portion with said sensing portion, said electrolytic medium covering the active area by not covering the outfacing surface of said sensing electrode, the electrolytic medium, the sensing electrode and the gas phase forming a 3-phase sensing boundary;
• a barrier covering said electrolytic medium, said barrier being permeable to an analyte gas;
• and
• an aqueous reservoir internal of said substrate in flow contact with said electrolytic medium.

A microsensor structure for sensing an analyte in a gas phase, comprising:

• a substrate having a substrate surface having an active area;
• a sensing electrode on the substrate surface having a sensing portion upon the active area, the sensing portion having an outfacing surface facing away from the substrate;
• a solid electrolytic medium covering the active area but not covering the outfacing surface, the electrolytic medium, the first electrode and the gas phase forming a 3-phase sensing boundary;
• a counter electrode in contact with the electrolytic medium and free from contact with the sensing electrode;
• and
• a reference electrode in contact with the electrolytic medium and free from contact with the sensing and counter electrodes;
• a barrier covering said electrolytic medium, said barrier being permeable to an analyte gas;
• and
• an aqueous reservoir internal of said substrate in flow contact with said electrolytic medium.

A microsensor structure, comprising:

• a substrate having a substrate having an active area;
• a first electrode on with said substrate surface, said first electrode having a sensing portion on said active area, said sensing portion having an infacing surface facing said substrate surface and an outfacing surface facing away from said substrate surface, said outfacing surface having an uneven configuration including a plurality of outwardly extending portions;
• an electrolytic medium covering said outfacing surface with said outwardly extending portions extending outwardly beyond said electrolytic medium and not being covered thereby;
• and
• a second electrode on said electrolytic medium and free from contact with said first electrode.

A microsensor structure, comprising:

• a substrate having a substrate surface having an active area;
• a first electrode in contact with said substrate surface, said first electrode having a sensing portion on said active area, said sensing portion having infacing surface facing said substrate surface and an outfacing surface facing away from said substrate surface;
• a solid electrolytic medium covering said outfacing surface, said solid electrolytic medium having a plurality of conductive microparticles dispersed therein;
• and
• a second electrode in contact with said electrolytic medium and free from contact with said first electrode.