After a quick introduction to the KID (Kinetic Inductance Detectors) basic principles, I will describe the development of the NIKA (Néel IRAM KID Arrays) instrument. NIKA, operating simultaneously at 150 and 250 GHz and covering a 2 arc-min field-of-view, has been the pathfinder for the KID technology during the period 2009 to 2014. In particular, it has been the first kinetic inductance camera ever on the sky (2009), and the first opened to the astronomers via competitive calls (2013). Among the science results obtained, we remind the first map of the kinetic SZ (Sunayez-Zeldovich) effect, resolving the intra-cluster medium velocity field within MACS J0717.5+3745. Other targets of NIKA: Pluto, interstellar dust filaments, a sample of galaxies clusters, nearby galaxies, debris disks etc.
In September 2012, we have started developing the ultimate NIKA2 (New IRAM KID Arrays 2) camera, containing 3000 pixels to fully cover the entire field-of-view of the 30-meters IRAM telescope (6.5 arc-min). NIKA2 has been successfully installed in September 2015, and is able to image the same portion of the Sky simultaneously at 150 and 250GHz, and map the linear polarisation at 250 GHz. After the first light obtained early in October 2015, NIKA2 underwent an extensive commissioning phase. Since April 2017, science targets are being observed, demonstrating the excellent sensitivity and performance obtained by the instrument that is since September 2016 in its final configuration .