Enhanced toluene gas-sensing properties of MEMS sensor based on Pt-loaded SnO₂ nanoparticles

Abstract

Rapid detection of low concentration toluene is highly desirable in environment monitoring, industrial processes, medical diagnosis, etc. In this study, we prepared the Pt-loaded monodispersed nanoparticles through hydrothermal synthesis and assembled a toluene sensor with fast response and low detection limits based on Micro-Electro-Mechanical System (MEMS). Compared with the pure SnO2, the 3 wt% Pt-loaded SnO2 sensor exhibits a 2.75 times higher gas sensitivity to toluene gas at about 330 °C. Meanwhile, the 3 wt% Pt-loaded SnO2 sensor also has a stable and good response to 100 ppb of toluene. Its theoretical detection limit was calculated as low as 12.6 ppb. Also, the sensor has a short response time of ~10 s at different gas concentrations (even down to 5.4 s at 20 ppm), as well as the excellent dynamic response-recover characteristic, selectivity, and stability. The improved performance of Pt-loaded SnO2 sensor can be explained by the increase of oxygen vacancies and chemisorbed oxygen. In our MEMS sensors, three gas sensing elements could be packaged in one ceramic shell for parallel testing and made it easier for real application by embedding in a printed circuit board. This provides new ideas and decent prospect for developing miniaturized, low-power-comsumption, and portable application of gas sensing devices.

Advancements and Prospects of Electronic Nose in Various Applications: A Comprehensive Review

“…Metal oxide semiconductors, which play a crucial role in gas sensing applications, are divided into two distinct groups based on their majority carriers. N-type MOSs, such as ZnO [62,63], In 2 O 3 [64,65], Fe 3 O 2 [62,66], TiO 2 [67,68], WO 3 [69,70], and SnO 2 [71,72], exhibit electrons as their majority carriers, whereas p-type semiconductors, including NiO [73], Co 3 O 4 [74], Cr 2 O 3 [75], Mn 3 O 4 [76], and CuO [77], have holes as their majority carriers.…”