“…Of the many sensors made to date for detecting trace chemicals in breath, tungsten oxide‐based sensors have shown great potential and have been used for detecting gases such as ethanol, acetone, NH 3 , formaldehyde, toluene, nitric oxide and H 2 S.(Righettoni, Tricoli, & Pratsinis, ; Staerz, Weimar, & Barsan, ; Supothina, Suwan, & Wisitsoraat, ; Tang, Jiang, Chen, & Wan, ) This is because tungsten oxide materials are easy to fabricate, low‐cost, and have excellent surface and material properties for applications as gas sensors. Sensors based on nanostructured WO 3 have been shown to be small, robust, inexpensive and highly sensitive.…”