Christian Simon is assistant professor at the University Pierre and Marie Curie (UPMC). He graduated from Chimie ParisTech as a chemical engineer. He holds a PhD. in condensed matter chemistry, and devoted 10 years to the molecular modeling of ionic liquid), using intensive quantum mechanics and statistical physics, porting several scientific computing codes and contributing to free software tools. A 3 years experience at the Ministry of Research as principal scientific advisor for nuclear wastes and nuclear safety let him discover the potential of citizen and participative sciences supported by FabLab/Hackerspaces applied to environment. With B. Ramond (UTC) and V. Dupuis he decided to boot the Sorbonne University FabLab. Since 2013, he is scientific leader of the OpenGeiger project.