Temperature estimation and tissue detection of an ultrasonic dissector from frequency response monitoring

An ultrasonic surgical apparatus comprising:

• a first signal generator outputting a drive signal at a predetermined frequency;
• a first oscillating structure, receiving the drive signal and oscillating at a frequency of the drive signal;
• a plurality of second oscillating structures integrally formed within a portion of the first oscillating structure, the plurality of second oscillating structures outputting electrical signals depending upon magnitude and frequency of a mechanical force applied to the plurality of second oscillating structures;
• and
• a microcontroller receiving the electrical signals output by the plurality of second oscillating structures, the microcontroller determining a temperature gradient along the plurality of second oscillating structures based on the received electrical signals by comparing the electrical signals from the plurality of second oscillating structures with a known signal value, and determining a temperature of the first oscillating structure based on the temperature gradient,
• wherein each second oscillating structure of the plurality of second oscillating structures is an accelerometer, and is positioned in proximity of an anti-node of harmonics of a resonant frequency of the first oscillating structure.