“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!

“The toaster really did work, and didn’t overheat the CPU! Just for fun, they also had control of the LEDs on the toaster. The keyboard was separate, connected via USB.”

links: news article, technical info