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We have previously shown that short pulses of focused ultrasound may be used to stimulate locally receptor neural structures and thereby induce sensations that humans can perceive through the skin (for example tactile, warmth and cold, tickling, pain, etc.). Furthermore, ultrasound modulated by sound signals (tone, speech, music, etc.) can induce sound sensations corresponding to the nature of the modulation in persons with normal hearing. The mechanism underlying these effects that have been used in clinical diagnostic practice is related to the radiation force. We also showed recently that the phenomenon of the radiation force could be used in perspective robotic systems, sensors, and automated control systems, based on the use of tactile sensations in the human‐machine interface, as well as in devices that may allow blind and visually impaired persons to perceive textual information presented on a tactile display. The research was supported by INTAS (05‐1000008‐7841) and RFBR (06‐02‐16079).

An ultrasound transducer array (24, 25, 26) suitable for medical uses such as tissue ablation and short duration high intensity hyperthermia has a plurality of ultrasound transducer elements (20a, 20b, 20c) dispersed across a substrate surface (21, 22, 23), for focusing ultrasound energy over a predetermined focal volume. Particularly optimal results are obtained where the elements (20a, 20b, 20c) are dispersed over the substrate surface in a quasi-random distribution, where the total radiating area of the elements occupying between approximately 40 and 70 % of the total array area, and the frequency of operation of the ultrasound elements and the average diameter of the elements are related according to the expression: d = A x c/f, where d is the average diameter of the elements, c is the velocity of sound in the medium to be irradiated with the ultrasound energy, lying in the range 1400 to 1600 m/s, f is the frequency of ultrasound energy and A is a value lying in the range approximately 0.5 to 5.