But when poachers carrying rifles or machetes traipse by a detector, it will send a radio signal to a treetop antenna.

ECONOMIST: Monitor

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.

ECONOMIST: Wine-tasting will never be the same again

Light striking this detector liberates electrons from some of the silicon atoms, producing an electrical signal that is converted by the chip's electronics into a picture.

ECONOMIST: Camera-phones