The study of the cold Universe allows us to go back to the origins of our solar system by observing the embryos of stars, or to the origins of the Universe by measuring the polarisation of the Cosmic Microwave Background (CMB). These sub-millimetre and millimetre instruments require the use of superconducting detectors cooled down to 100mK. Kinetic Inductance Detectors (KIDs) are based on superconducting resonators and are about to replace bolometers thanks to their natural frequency multiplexing and ease of production (in their basic form).