Would it be possible to make a virus detector for use at say the entrance to supermarkets etc?
Initial thought would be to use a laser and photodetector. To detect scatter from particles.
The person would blow through an orifice, preferably without touching it though! The laser and photodetector would be mounted at right angles, so that the breath is checked for viruses by light scattering from them.
This technique is used for detecting bacteria:
This article describes use of a reflective sphere, but not sure how that would work in practice. A reflective tube would be more practical. For example an aluminium can with the ends removed.
Also, it could be made insensitive to ambient light by driving the laser with a squarewave, and synchronously detecting (lock in amplifier technique) the photodetector output.
It would not be able to distinguish different types of virus. And also something would need to be done to avoid false alarms from particles such as pollen and exhaust fumes.
Does anyone have some spare time to have a go? I need to focus on the oxygen generator for now.