High sensitive mass detection in liquid using a piezoelectric GaAs membrane

In this study, we developed a specific GaAs acoustic sensor adapted for molecules detection in biological media. The design was performed taking in mind that the device will be in contact with liquid. The resonant structure is a membrane. Microfabrication processes based on anisotropic chemical etching were used to obtain the right structure. The best performance was obtained in a (100) wafer with an electric field aligned along <;110> direction. For a membrane thickness of 50 μm, f_R is close to 33.36 Mhz and the sensitivity is higher than for QCM and is similar to the values obtained using SPR techniques.