Following is a summary of the six leading manufacturers of shock wave devices. Each manufacturer concentrates on different medical applications, using one of three methods of shock wave generation. These are, electrohydraulic, piezoelectric and electromagnetic.
Electrohydraulic shock waves are generated from high-voltage electrode sparks that cause explosions in water. The energy is then focused with an elliptical reflector. First generation devices used this technology, but the energy is harder to control and is being superseded by the other two technologies.
Piezoelectric shock waves are generated by an electrical discharge through piezo crystals mounted on a parabolic surface.
Electromagnetic shock waves are generated by passing an electric current through a coil to produce a strong magnetic field, in a similar manner to an audio speaker. Some devices use a flat source with an acoustic lens to focus the waves, others use a cylindrical coil with a parabolic reflector.
There is an important distinction between devices that generate shock waves that are “radial” – that is they radiate from the head and dissipate, and “focused” – where the shock waves converge at a point.