The purpose of this project is to create a new generation of integrated mechanical micro-resonators for high-selectivity and sensitivity gas photoacoustic detection (sub-ppm concentrations), in a very compact, robust, portable system. In photoacoustic spectroscopy, measurement is performed by a microphone or mechanical resonator, using the acoustic pressure generated by the local warming caused by optical absorption. Mechanical resonators installed in the gas chamber provide high sensitivities, but they are not specifically developed for this application. The NOMADE project aims to develop micro-resonators specially designed for this application. A significant gain on the detection performances is expected. This new technology will allow placing the laser next to the micro-resonator, eliminating the need for any optical element. This compactness allows totally rethinking gas sensors, which can now be understood as a modular element easy to integrate in a more complex system.