This study is focused on the propagation behaviors of antisymmetric flexural (ASF) modes propagating along the apex of piezoelectric wedges. The dispersion behavior of the ASF modes in isotropic wedges attracts many studies. However, for more complex materials such as piezoelectrics, the propagation behaviors of the ASF modes are not studied on the basis of the anisotropy and piezoelectric effects. The purpose of this study is to investigate the behaviors of the ASF modes propagating along the apex of piezoelectric wedges with a combined numerical/experimental study based on finite element simulations and laser ultrasound measurements. Wedge samples are prepared from lithium niobate (LiNbO 3 ) wafers. The phase velocities of the ASF modes as a function of propagation angle and their relation with Rayleigh wave speeds are characterized.

This paper describes the design and characterization of a capacitive tactile sensor fabricated in a conventional CMOS process. To achieve a high capacitive sensitivity, an oscillator circuit is adopted to convert the pressure induced capacitive change to an output frequency shift. The complete post micromachining steps are performed on a CMOS die without resorting to a wafer process. The pressure-sensing membrane has a total size of 200 µm × 200 µm with an initial sensing capacitance of 153 fF. Experimental results show an initial frequency output at 48.96 MHz under no applied load. The total frequency shift is 13.5 MHz with a corresponding membrane displacement of 0.56 µm and a capacitance change of 63 fF, averaging 0.21 MHz/fF. The measured force sensitivity is 26.1 kHz/µN.