A biosensor for measuring an electrical response from a biological sample. The biosensor includes a substrate, a passivation layer grown on a surface of the substrate, a patterned catalyst layer deposited on the passivation layer, and three electrodes grown on the patterned catalyst layer. The three electrodes include a working electrode, a counter electrode, and a reference electrode. The working electrode includes a first array of electrically conductive biocompatible nanostructures that is configured to be an attachment site for the biological sample. The counter electrode includes a second array of electrically conductive biocompatible nanostructures that is configured to acquire the electrical response from the working electrode. The reference electrode includes a third array of electrically conductive biocompatible nanostructures that is configured to adjust a specific voltage around the working and the counter electrodes.

A sensor element includes an element body including an oxygen-ion-conductive solid electrolyte layer, the element body having a longitudinal direction, a measurement electrode disposed in the element body, a reference electrode disposed in the element body so as to come into contact with a reference gas, and a heater configured to heat the solid electrolyte layer. A center of gravity of the reference electrode overlaps the measurement electrode as viewed in a thickness direction of the solid electrolyte layer. A length of each of the reference electrode and the measurement electrode in a front-rear direction is less than or equal to 1.1 mm, the front-rear direction being a direction along the longitudinal direction of the element body. An area of the reference electrode as viewed in the thickness direction is greater than or equal to 1.0 mm.sup.2.

A carbon dioxide sensor includes: a solid electrolyte layer that is anion conductive; a reference electrode disposed on one surface of the solid electrolyte layer; and a detection electrode disposed on the other surface of the solid electrolyte layer. The detection electrode is made of a mixture containing: (a) one or more metals selected from the group consisting of Au, Ag, Pt, Pd, Rh, Ru, Os, and Ir; (b) a cation conductive carbonate; and (c) an oxide containing Li and at least one of Ce and Sm. The solid electrolyte layer is preferably oxide ion conductive, and the cation conductive carbonate is preferably lithium ion conductive.

A membrane electrode assembly of an electrochemical device includes a proton conductive solid electrolyte membrane and an electrode including Ni and an electrolyte material which contains as a primary component, at least one of a first compound having a composition represented by BaZr.sub.1-x1M.sup.1.sub.x1O.sub.3 (M.sup.1 represents at least one element selected from trivalent elements each having an ion radius of more than 0.720 A° to less than 0.880 A°, and 0<x.sub.1<1 holds) and a second compound having a composition represented by BaZr.sub.1-x2Tm.sub.x2O.sub.3 (0<x.sub.2<0.3 holds).

There is provided a method of manufacturing a gas sensor that includes: forming an insulating layer on a main surface of a substrate; forming a porous oxide layer on the insulating layer; and forming a porous metal layer on the porous oxide layer, wherein the forming the porous metal layer is performed by depositing a constituent material of the porous metal layer in an inclined direction with respect to a normal line of a main surface.

In a sensor element for a limiting-current type gas sensor measuring concentration of NOx in a measurement gas, an inner pump electrode located to face a first internal space communicating, under predetermined diffusion resistance, with a gas inlet through which a measurement gas is introduced from an external space is made of a cermet of a Pt—Au alloy and zirconia, and includes a first portion located on a surface farther from a heater part and a second portion located on a surface closer to the heater part from among surfaces opposing each other in the first internal space, an Au content with respect to the Pt—Au alloy as a whole of the second portion is 0.3 wt % or more smaller than that of the first portion, and a total area of the first portion and the second portion is 10 mm.sup.2 to 25 mm.sup.2.

A gas sensor includes a gate electrode; a dielectric layer covering one surface of the gate electrode; an indium (In) gallium (Ga) zinc (Zn) oxide (O) (IGZO) thin-film formed over the dielectric layer, and first and second metallic electrodes formed on a surface of the IGZO thin-film to act as source and drain, respectively. The IGZO thin-film has an In concentration of 11%+/−3%, Ga concentration of 11%+/−3%, Zn concentration of 7%+/−3%, and 0 concentration of 71%+/−3%, with a sum of the concentrations being 100%, and the gas interacts with the IGZO thin-film and changes a current through the IGZO thin-film.

A gas sensor includes a first electrode, a gas detecting layer disposed on the first electrode, and an electric-conduction enhanced electrode unit being electrically connected to the first electrode and the gas detecting layer. The electric-conduction enhanced electrode unit includes an electric-conduction enhancing layer and a second electrode electrically connected to the electric-conduction enhancing layer. The electric-conduction enhancing layer is electrically connected to the gas detecting layer and is made of an electrically conductive organic material.

A gas sensor includes a first electrode, a gas detecting layer disposed on the first electrode, and an electric-conduction enhanced electrode unit being electrically connected to the first electrode and the gas detecting layer. The electric-conduction enhanced electrode unit includes an electric-conduction enhancing layer and a second electrode electrically connected to the electric-conduction enhancing layer. The electric-conduction enhancing layer is electrically connected to the gas detecting layer and is made of an electrically conductive organic material.

A hydrogen gas sensor with a substrate and a zinc oxide nanostructured thin film deposited on the substrate, wherein the zinc oxide nanostructured thin film has a lattice structure with a weight ratio of low binding energy O.sup.2− ions to medium binding energy oxygen vacancies in a range of 0.1 to 1.0, and a method of fabricating a gas sensor by thermally oxidizing a metal thin film under low oxygen partial pressure. Various combinations of embodiments of the hydrogen gas sensor and the method of fabricating the gas sensor are provided.