US Patent 10022567 Devices and techniques for cutting and coagulating tissue

Various embodiments are directed to a method of driving an end effector coupled to an ultrasonic drive system of a surgical instrument. In accordance with the method, a generator is configured to generate at least one time varying electrical signal having a resonant frequency, monitor the resonant frequency of the at least one electrical signal, compare the resonant frequency to a threshold frequency, and trigger a first response of the generator when the resonant frequency crosses the threshold frequency.