Design of a Tactile Display Based on a High Power CMUT Array

In this paper we present the optimization of a Capacitive Micro machined Ultrasonic Transducer (CMUT) array that performs as a tactile display using an electrical equivalent circuit model and the SPICE program. The array implements a "pixel" of the display and is used to focus airborne ultrasound energy on the skin surface. The design of the array is optimized for high output so that the pressure field generated by the focused ultrasound waves excites the mechanoreceptors under the skin and transmits tactile information. The geometry of the individual transducer and the array are optimized so that the medium presents maximum impedance and the membrane oscillates with maximum deflection. Finite element analysis of the CMUT and the CMUT phased array is used to verify the SPICE results. In order to verify the feasibility of the design, the pressure at focal point is compared with the pressure threshold required for mechanoreceptor excitation.