As of this making, a SARS-CoV-2 pandemic creates an incentive to sterilize FFP2 masks for re-use. The temperature should stay around 80°C, but household appliances don't offer digital temperature readout or control, instead relying on bimetallic thermostat switches with about 10 K hysteresis.
A safe and scalable solution would be to use
* mass-produced and certified toaster ovens
* remote controlled mains sockets
* a simple microcontroller board with 433 MHz transmitter and thermocouple interface
mains-connected temperature controllers and industrial PID controllers are an order of magnitude more expensive and cannot be procured in sufficient quantities on short notice, while toaster ovens and remote controlled switches are ubiquitous and thus suited for situational response.
The core of this project will focus on describing and qualifying the proposed approach and on providing a cheap and simple microcontroller solution for its control.
Initially, I saw this project by Vince float by on twitter which describes how to rework a sandwich toaster reflow oven. Useful, but currently I'm sure more people need to re-use their more expensive FFP2 masks. This build is close, but I'd like to turn it into something that's safe and that one can instruct other people to build without breaking certifications safety mechanisms that the appliances already come with. Preferably one would also want to use them again for their original purpose after the pandemic, creating no, or only a minimum of additional e-waste.