"The device works by sucking in particles of caramelised bread and blowing them through an ionising sensor. In this sensor a small electrical current flows through an airborne path of ions, emitted by a pellet of radioactive americium-241. The ions attach themselves to any toast particles and reduce the strength of the current. You can set the toaster to switch off when the current drops by a specific amount according to how brown you like your toast." Read the article!