Embodiments described herein include the device of an electrical interface and a processor. Processor is configured as receiving one first signal of instruction its a part for being applied in tissue of one time-varying force, the one or more second signals obtained by the ultrasonic reflection received from portion of tissue via electrical interface. Processor is further configured to learn to the first signal and second signals, the dependence to a thickness of the portion of tissue for the power for being applied to portion of tissue. Also describe other embodiments.
