Metal Oxide Based Sensors for Sensing Low Concentration of Specific Gases Prepared by A Flame Based Process

A sensor assembly comprising:

• a substrate, the substrate a micro-electro-mechanical-system substrate having a set of gold or platinum inter-digitated electrodes;
• a dopant-free metal oxide film deposited on the substrate, the dopant-free metal oxide film having amorphous phase boundaries between nanoparticles of the dopant-free metal oxide film, the nanoparticles having a size from about 2 nm to about 30 nm;
• wherein the dopant-free metal oxide film includes gamma WO3 or epsilon WO3;
• wherein the dopant-free metal oxide film is porous and has a film thickness of from about 500 nm to about 3 microns;
• wherein the dopant-free metal oxide film has uniform necking between nanoparticles of the dopant-free metal oxide film;
• wherein the dopant-free metal oxide film is adapted to facilitate detection of an analyte in a sample;
• wherein the analyte is a component of exhaled breath that correlates with a health condition;
• and
• wherein the dopant-free metal oxide film is adapted to facilitate detection of the analyte for about 450 hours of continuous testing of the sample at a working temperature of from about 250° C. to about 400° C.