Dual sterilization and temperature based sterilization detection

A reusable assembly of a surgical instrument, comprising:

• (a) an inner tube including at least one opening;
• (b) an ultrasonic blade positioned within the inner tube, wherein the at least one opening of the inner tube is fluidly open and thereby configured to receive a sterilization fluid therethrough from an exterior of the inner tube to the interior of the inner tube for sterilizing the ultrasonic blade within the inner tube;
• and
• (c) a sterilization detection system, including:
• (i) a thermal switch configured to move from an open state to a closed state when the thermal switch is above a predetermined temperature threshold,
• (ii) a clock operatively connected to the thermal switch and configured to measure an elapsed time when the thermal switch is in the closed state, and
• (iii) a controller operatively connected to the clock and configured to determine whether a sterilization cycle has occurred based on elapsed time measured by the clock.

A method of determining that a reusable portion of a surgical instrument has been sterilized, comprising:

• (a) closing a thermal switch to a closed state when the reusable portion is subjected to a higher temperature above a predetermined temperature threshold;
• (b) measuring an elapsed time when the reusable portion is above the predetermined temperature threshold;
• (c) opening the thermal switch to an opened state when the reusable portion decreases from the higher temperature to a lower temperature less than or equal to the predetermined temperature threshold to thereby stop measuring the elapsed time;
• and
• (d) comparing the measured elapsed time to a sterilization condition to thereby determine that the reusable portion has been sterilized during a sterilization cycle.