The elaboration of new soft hybrid materials requires adapted smart sensors. Among the ultrasonic techniques, the use of an AT cut quartz is a solution that allows the complete tracking of the mechanical properties of the material in contact. In order to get a RF wireless excitation of such a sensor in a wide frequency bandwidth, the tuning of the electrodes geometry is determinant as it must be based on closed loops. The aim of the present experimental study is to analyse the role played by the electrodes shape upon the generation of the surface waves. Several electrodes excitation geometries are presented in order to optimize the surface wave focusing at the center of the sensor. The quartz disk is excited by a voltage pulse and the quartz surface is scanned by a laser vibrometer (JOPCS, 195, 1-8 (2009)). The surface waves and the transient aspects linked to the electrodes shape borders are analysed by using the 3D Gabor transform (Ultrasonics, 43, 1173-1177 (2006)). The observed waves and their generation sources are presented, revealing new insight about the modelisation of the sensor electrodes. A comparison with classical electrodes shapes is carried out.