Do Silicon Ultrasonic Transducers Dream of Becoming Mobile Tactile Display?

Abstract

Abstract-In today's research for the better human-computer interfaces, tactile sensation is one of the most technologically immature, yet the most intensely studied topics. Ultrasonic sound waves as the sensation generator are commonly adopted. Conventional ultrasonic sound source devices employ piezoelectric transducers and thus suffer from the cost and integration issues. In this work we examined theoretically the possibility of exploiting the capacitive micromachined ultrasonic transducers (CMUTs) as a tactile display device that generates two-dimensional pressure distribution above their surface via near-field acoustic radiation pressure effect. We found that with slight modification to existing CMUT geometry, 300Pa necessary for invoking tactile sensation is achieved with the spatial resolution of 3.8mm close to the average two-point discrimination threshold of 3mm. The possibility to go further below the 3mm threshold by halving the CMUT radius is also pointed out.