A new approach of chemical sensors is presented in this work. The physical effect used by this new type of sensor is based on perturbations of the sensitive coating properties : the sorption of specifics species by the sensitive layer modifies its physicochemical characteristics inducing frequency shift and also bending variation. An analytical modelling has led to optimize geometrical microcantilever parameters. To monitor the resonant frequency, the microcantilevers have been inserted in the retroaction loop of an amplifier to constitute an oscillator. Experimental results have shown the mass loading effect sensitivity. Then, ethanol detection has been realized and obtained results have been compared to theoretical modelling.