There is an interesting project that is using the Americium-241 from a smoke detector to produce an entropy source based on radioactive decay.
https://hackaday.io/project/180445-qrng
They do this without having to disassemble the chamber that contains the Americium-241, limiting personal exposure.
I find this interesting because I live outside the United States. There are companies in the U.S. where you can buy mildly radioactive materials for use with Geiger counters to produce radioactive-decay entropy sources. But exporting radioactive material from the U.S. and into another country would be a challenge, if not an International Traffic in Arms Regulations violation. But everybody has smoke alarms.
https://hackaday.io/project/180445-qrng
They do this without having to disassemble the chamber that contains the Americium-241, limiting personal exposure.
I find this interesting because I live outside the United States. There are companies in the U.S. where you can buy mildly radioactive materials for use with Geiger counters to produce radioactive-decay entropy sources. But exporting radioactive material from the U.S. and into another country would be a challenge, if not an International Traffic in Arms Regulations violation. But everybody has smoke alarms.