Pulsed ultrasonic device and method

Abstract

This invention relates to an improved method and apparatus for generating profiled pulses of ultrasonic frequency vibratory energy at a distal surface of an ultrasonic applicator of an ultrasonic surgical instrument for application to tissues of a patient, including the providing of a profiled pulse signal with a first profile and a maximum magnitude during a first time portion and a second profile and a minimum magnitude during a second time portion, the second time portion being greater than or equal to the duration of the first time portion, the first time portion being between one millisecond and fifty milliseconds in duration, and the maximum magnitude in the range between two and twenty times the minimum magnitude.

1 . An ultrasonic surgical apparatus for delivery of profiled pulses of ultrasonic frequency vibratory energy, the ultrasonic surgical apparatus with a housing to be held and manipulated by a user, an ultrasonic motor supported within the housing, an ultrasonic applicator connected to the ultrasonic motor and extending beyond the housing, the ultrasonic applicator with a distal surface for engagement with tissues of a patient and, in combination with the ultrasonic motor, vibratable at a resonant frequency, and the improvement comprising: 
 a power control circuit electrically connected to the ultrasonic motor for supplying electrical power to the ultrasonic motor to produce ultrasonic frequency vibratory energy that is applied to the ultrasonic applicator;    a vibration monitor circuit electrically connected to the power control circuit for measuring an electrical vibration signal at the resonant frequency and proportional to a vibratory amplitude of the ultrasonic applicator so that the power control circuit supplies electrical power to the ultrasonic motor at the resonant frequency, and    a profile generator circuit electrically connected to the power control circuit for producing a profiled pulse signal, the profiled pulse signal with a first profile and a maximum magnitude during a first time portion and a second profile and a minimum magnitude during a second time portion, the second time portion being equal to or greater than, but no more than three times the duration of the first time portion, the first time portion between one millisecond and fifty milliseconds in duration, and the maximum magnitude in the range between two and twenty times the minimum magnitude, so that, in combination with the electrical vibration signal, the power control circuit adjusts the supply of electrical power to the ultrasonic motor to produce profiled pulses of ultrasonic frequency vibratory energy.