A recent study published in ACS Sensors highlights the development of a smart electronic nose (e-nose) by a research team led by Prof. MENG Gang from the Hefei Institutes of Physical Science of the Chinese Academy of Sciences. The novel e-nose utilizes self-heating modulation strategy to accurately distinguish different types of target gas molecules within only one second.

Significant progress has been made in gas molecule detection using e-nose comprised of non-selective semiconductor gas sensors. However, extracting adequate molecular features in a short time (<1 second) remains a major obstacle, which hinders the early warning applications of e-nose for lethal or explosive gases.

In this study, an innovative approach for temperature control and modulation was developed as an alternative to the conventional method using external heaters. A tungsten trioxide (WO₃) nanorod film prepared by oblique angle deposition (OAD) was used as both a sensitive sensing layer and a stable self-heating layer. Due to the ultrafast (～20 μs) thermal relaxation time, the OAD WO₃ sensor can generate sufficient electrical response features via self-heating temperature modulation.

This advancement has led to the accurate discrimination of 12 gas molecules within 0.5-1 second, which is one order faster than the state-of-the-art e-noses. 

In addition, a smart wireless e-nose system was developed tp enable accurate and instantaneous identification of target gases in ambient air backgrounds.

This development demonstrated the potential applications of e-nose in the area of public health, according to the team.

Smart E-nose system based on the self-heating temperature modulation. (Image by LI Meng)