Do you like to cuddle up in your favorite blanket..with or without socks ?
Little dogs advice is ok, except that UHF wireless mics are illegal in the USA unless you can obtain an FCC license. The FCC just discovered that a lot of pirate users in the band and they have until April to vacate. Yes UHF mics work good, but you have to be a broadcast entity to qualify for a license because of the potential to interfer with UHF television station reception. The manufacturers are currently under a lot of pressure from the FCC to recall mics from illegal users, ie Churches, sports arenas, theaters and such. Watch for the new legal products for you to buy soon.
Fire detectors are optical sensors that if they detect either a certain change in illumination or a enough illumination are triggered.
Fire sensors are usually smoke detectors. They are based on a radioactive source and a very sensitive ionization measurement. That's probably nothing you want to do at home. But you could do an optical smoke detector. The light path between an IR light source and a photodetector will be interrupted by smoke. I am pretty sure this will work if you can afford to make it a couple of feet long (or longer). Another possibility would be to detect CO2 and CO. There are chemical sensors out there for that purpose.
