Ballistic Pain Therapy Devices: Measurement of Pressure Pulse Parameters

Ballistic pressure pulse sources are used for the treatment of soft tissue pain. The devices use a technical principle, which is known from air guns, i.e. a projectile is accelerated by pressurized air towards a metal plate (applicator). At the patient side, a fast (4..5μs), almost singular pressure pulse of 2..10 MPa is created, which is followed by an equally short rarefaction phase of about the same amplitude. In order to characterize the pressure pulse devices, a “dry” test bench was built mimicking the properties of the patient skin by a silicone layer. Comparison of measurements in water and with the silicone layer demonstrated, that the pressure pulses could be reproduced almost identical in both situations. At present, 4 different hand pieces were evaluated using the “dry” test bench. The behaviour of the hand pieces when the pulse repeat rate was changed from single pulse to maximum rate (20..21 per second) was assessed. It turned out, that the pulse amplitudes and intensities depend strongly on the type of hand piece, and on the driving pressure. A decrease of peak pressure down to 63% was found at a pulse rate of 20 Hz as compared to single pulse amplitude at the same driving pressure. Further measurements show, that a strongly damped, low amplitude inertial oscillation of ca. 10 ms period follows after each pressure pulse.