Abstract: A method performed by a surgical system. The method determines that an ultrasonic instrument is in a low-power state The method determines a resonance frequency of an end effector of the ultrasonic instrument and determines a temperature of the end effector based on the resonance frequency. A notification is displayed on a display of the surgical system based on the temperature.

Abstract: A method performed by a surgical system that includes an ultrasonic instrument with an end effector. The method determines a change in resonance frequency of the end effector while the ultrasonic instrument is either in 1) a high-power state in which the ultrasonic instrument draws a first current to cause the end effector to produce heat or 2) a low-power state in which the ultrasonic instrument draws a second current, which is less than the first current that does not cause the end effector to produce heat. The method determines a temperature of the end effector by applying the change in resonance frequency to a hysteresis model that includes a hysteretic relationship between changes in resonance frequency of the end effector and corresponding temperatures of the end effector, and outputs a notification based on the temperature.