Modulation of the driven signal applied to an ultrasound therapy transducer

Studying the wave propagation and the cellular effects of the ultrasound energy emitted by physiotherapy equipments has been the direction of the past research issues. There are many publications about the effectiveness of ultrasound to treat some physical diseases but there is still few dealing with temperature distributions produced by this kind of equipment. Some companies have developed commercial ultrasonic devices for physiotherapy that have the following classical features: stable output of either continuous or pulsated mode (duty cycle), delivered power smaller than 3 W/cm², and frequencies of either 1 or 3 MHz. Each equipment has its own protections and limits, and it is not easy to adjust some parameters; hence, using commercial equipment for research purposes limits research work. We propose a physiotherapy ultrasonic apparatus to induce heating in phantoms. Temperature distribution results in phantoms, obtained from these experiments, can be compared with those obtained from mathematical modeling. The device can deliver a modulated ultrasonic signal at frequencies and waveforms chosen by the user. This paper shows the first approximation to the complete design.