Metrological characterization of a therapeutic device for pressure wave therapy

This study aims to characterize an electromedical device used for pressure wave therapy delivered by shock waves. The test protocol analyses different pressures and evaluates both the tip displacement, by means of a laser Doppler vibrometer, and the transmitted force, by means of a piezoelectric load cell; a silicone rubber was used as a tissue phantom. Finally, the provided energy density in terms of J/m² was computed. Results show variability in the tip displacement values (up to 15%), particularly at the lower working pressure values. It is also possible to note that the higher is the value of the pressure created by means of the solenoid valve, the higher is the force transmitted to the tissues (i.e. hundreds of N). Also the force data are affected by a certain degree of variability (up to 18%). Such study allows to better understand the effective force delivered to the tissues and to optimise the energy density provided to the different patient's districts, specifically at high pressures (i.e. ≥3 bar; 300 kPa) and on soft tissues (e.g. skin and connective tissue) where the energy densities can reach the limits indicated in DIGEST and ISTMT guidelines (i.e. 300 J/m²). Consequently, it is important that the operators of such machines carefully evaluate the machine operating settings in order to maximise the benefits.