Read this to learn how basically e-noses are relegated to science fiction for the next 20 years at least:
How to make electronic noses smell better
Apr 2023, phys.org
via Xi'an China Northwestern Polytechnical University: Taoping Liu et al, Review on Algorithm Design in Electronic Noses: Challenges, Status, and Trends, Intelligent Computing (2023). DOI: 10.34133/icomputing.0012
'Electronic nose' built with sustainably sourced microbial nanowires could revolutionize health monitoring
Feb 2023, phys.org
Grown by bacteria. Great, but each nanowire needs to be programmed for each molecule, so a typical top-down approach.
via University of Massachusetts Amherst: Yassir Lekbach et al, Microbial nanowires with genetically modified peptide ligands to sustainably fabricate electronic sensing devices, Biosensors and Bioelectronics (2023). DOI: 10.1016/j.bios.2023.115147
A robot able to 'smell' using a biological sensor
Jan 2023, phys.org
10,000 times higher than the usual electric-based sensors, these are now biological sensors (not sure the difference). And then they program a "library of smells", so keep in mind that, like all other smell sensors out there, these don't just smell anything that happens to be in the environment -- they can only smell things that have been pre-selected and trained-on.
via Tel Aviv University's Sagol School of Neuroscience and School of Zoology: Shvil Neta et al, The Locust antenna as an odor discriminator, Biosensors and Bioelectronics (2022). DOI: 10.1016/j.bios.2022.114919
New devices for conveying olfactory stimuli in virtual reality
May 2023, phys.org
Aerosols and atomizers add bulk to VR gear and entail bottle filling and cleaning. This new approach uses paraffin imbued with scents, released by a temperature-sensing resistor that controls a heating element - the more heat the more scent. But wait -- magnetic induction coils pull heat away from the face to cool the wax quickly when the scent is no longer needed.
The removal of scent is actually the harder problem to solve than the introduction of scent in these kinds of systems.
via City University of Hong Kong, Beihang University and Shandong University: Yuhang Li, Soft, miniaturized, wireless olfactory interface for virtual reality, Nature Communications (2023). DOI: 10.1038/s41467-023-37678-4