Its reaction with the odour molecules changes a detector's electrical resistance, and this signal is fed into a neural net (the closest that computer technology has got to imitating the pattern-recognising abilities of networks of nerve cells) to work out what is being smelt.
But one genome pioneer is taking the opposite approach: imitating the open-source movement of computer science, which argues that technology works best when it is given away for free so that everyone can collaborate on it.