Study of a Highly Sensitive Formaldehyde Sensor Prepared With a Tungsten Trioxide Thin Film and Gold Nanoparticles

A new gold (Au) nanoparticle (NP)/tungsten trioxide (WO
₃
)-based chemoresistive formaldehyde gas sensor is fabricated and reported. The WO
₃
thin film and Au NPs are prepared by radio frequency (RF) sputtering and rapid thermal evaporation (RTE) approaches, respectively. The utilized Au NPs successfully elevate the surface area/volume (
${S}_{A}/{V}$
) ratio and improve corresponding sensing performance. Experimentally, the proposed Au NP/WO
₃
sensor shows a very high sensing response of 1303.5 and a response (recovery) time of 16 s (16 s) under introduced 20 ppm formaldehyde (HCHO)/air gas at 225 °C. This value is remarkably higher than those of previous reports. In addition, a very low detection content of 40 ppb HCHO/air is obtained, revealing that a widespread detection range of formaldehyde concentration can be acquired for the proposed sensor. To expand the application ability in wireless sensing, a gray algorithm GM(1, 1) model incorporating the first-order differential approach is used to substantially diminish the transmission data, increase the transmission efficiency, and improve the accuracy of the response data. The formaldehyde sensor in this study exhibits advantages including a simple structure, ease of manufacturing, relatively lower cost, practical smart sensing ability, and wireless transmission applications.