I think they have left it for health approval I was seeing it yesterday in the group of coronavirus makers. I’m printing visors for doctors and police in coronavirus makers.
I thought about brushless motors, I think that with one and a turbine generates enough air, They are quiet and durable. You have to find engines that can work more than 40 days without stopping. Turbine printed with dental resin in FDM or SLA could be pass the medics test I think. Or in metal with CNC or Laser.
Brushless motors need a ESC, I have some designs with fortior and others chips that are very used in fpv drones.
This could reduce and simplify the mechanical part of the respirator.
I think that respirator need a RTOS, this is mission critical, and if the
pressure sensor detects that there is no pressure immediately activates the other motor, with a support that facilitates the extraction of the motor in case it has to be replaced.
Another thing I’ve been thinking about is having the ability to add a UV filter. I have been reading that this improves air quality. It also has another function which is to disinfect. UV light with a color between 200nm and 300nm can kill viruses.
lcsc has release a new UV light driver for coronaviurs. This is the project https://easyeda.com/EasyEDA-Team/uv_light_control