Abstract: A gas sensor includes a plurality of loosely connected metal oxide nanoclusters configured to provide a porous structure, the metal oxide nanoclusters having an average characteristic length of 1 nm to 20 nm, and a coating made with catalytic material is deposited on an outer layer of the metal oxide nanoclusters.

Abstract: A method and apparatus of determining an elastic modulus of a material having a Poisson's ratio v by a Berkovich indenter having an elastic modulus E; a Poisson's ratio v, and a cross sectional area A(h) as a function of depth are provided. The method and apparatus model the Berkovich indenter with a conical shape and a spherical cap.

Abstract: Errors in current methods of determining elastic modulus through depth-sensing indentation may be resulted from three major factors: 1. error in estimating the projected contact area A(hc) by indirect means such as from the unloading curve, especially in the cases where “piling-up” occurs; 2. reliance on the use of the initial unloading slope Su, which in some cases is not easily determined reliably; and 3. insufficient consideration on the influences due to indenter bluntness in some important models based on numerical treatments. This invention provides a new method of determining elastic modulus of an indented material, which overcomes the above deficiencies. The maximum load and the total displacement of the indenter (to give a nominal hardness defined in this invention), elastic work and total work are measured.