most smoke detectors work on the principle of change in the light falling on a photodetector due to presence of smoke in between the light source and the detector.. so you really dont need any high-fundoo designs too.. if you are very good at analog design, you can make all sorts of smoke detectors without any embedded technology... the principle remains the same...
as for the ionization technology idea, my opinion is that it really isnt required unless you are looking for a particular smoke.. i mean smoke with a particular chemical content...
did i help?
regards,
wiztronix