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Devices and techniques for cutting and coagulating tissue

  • US 9,237,921 B2
  • Filed: 03/15/2013
  • Issued: 01/19/2016
  • Est. Priority Date: 04/09/2012
  • Status: Active Grant
First Claim
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1. A method of driving an end effector coupled to an ultrasonic drive system of a surgical instrument, the method comprising:

  • generating, by a surgical generator, at least one electrical signal;

    comparing, by the surgical generator, an ultrasonic impedance of the surgical instrument to an impedance threshold;

    determining, by the surgical generator, that the ultrasonic impedance of the surgical instrument has exceeded the impedance threshold;

    determining, by the surgical generator, that a present resonant frequency slope of the at least one electrical signal differs from a past resonant frequency slope of the at least one electrical signal by more than a frequency slope threshold; and

    triggering, by the surgical generator, a first response.

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