A gravimetric quartz sensor has been developed for the specific detection of immunological interactions. Antibodies were immobilized through oriented covalent coupling onto the functionalized quartz transducer. The experimental set-up, to study the immunosensor response, consists of a differential measurement system that allows extraction of only the immunological signal. A cell and a suitable computer program for acquisition and treatment of data were developed to overcome the shortcomings encountered with these acoustic sensors. The variations in resonant frequency and quality factor, i.e. the resonance parameters, of two loaded resonators (immunosensor and reference), are related to the variations in the shear acoustic impedance of the loading materials. This original impedance analysis shows the changes in rigid mass deposit in contrast to interfacial viscous load.