Methods and systems for controlling an ultrasonic handpiece based on tuning signals

1. A method of controlling an ultrasonic handpiece, said method comprising:

sensing a pressure between the ultrasonic handpiece and a surgical implement disposed within the body of a patient;

comparing the sensed pressure between the ultrasonic handpiece and the surgical implement to a predetermined pressure range to determine if the sensed pressure is within the predetermined pressure range, the predetermined pressure range indicating that the sensed pressure between the ultrasonic handpiece and the surgical implement is ready for welding;

applying a first tuning signal to the ultrasonic handpiece only when the pressure between the ultrasonic handpiece and the surgical implement is determined to be within the predetermined pressure range, the first tuning signal having a first variable frequency within a predetermined frequency range between 19.5 kHz and 20.7 kHz;

detecting a first impedance and a second impedance of the ultrasonic handpiece in response to the first tuning signal;

comparing the first impedance to the second impedance;

applying a second tuning signal to the ultrasonic handpiece, the second tuning signal having a second variable frequency within the predetermined frequency range; and

transferring, when the pressure between the ultrasonic handpiece and the surgical implement has settled within the predetermined pressure range for at least a predetermined settling interval, vibratory energy through the ultrasonic handpiece to the surgical implement to form a weld at the surgical implement for stabilizing body tissue with the weld, wherein the predetermined settling interval is 2 seconds.

2. The method of claim 1 wherein said comparing the first impedance to the second impedance comprises determining whether a difference between the first impedance and the second impedance is less than a predetermined threshold.

3. The method of claim 1 further comprising:

detecting a third impedance and a fourth impedance of the ultrasonic handpiece in response to the second tuning signal;

comparing the third impedance to the fourth impedance; and

applying a third tuning signal to the ultrasonic handpiece, the third tuning signal having a third variable frequency within the predetermined frequency range.

4. The method of claim 3 wherein said comparing the third impedance to the fourth impedance comprises determining whether a difference between the third impedance and the fourth impedance is less than a predetermined threshold.

5. A surgical generator for use with an ultrasonic handpiece, said surgical generator comprising:

a processing device; and

a memory device comprising a tangible, non-transitory computer readable medium having encoded thereon computer-readable instructions that are executable by the processing device to perform functions comprising:

receiving a pressure signal from a pressure sensor indicative of a pressure between the ultrasonic handpiece and a surgical implement disposed within a body of a patient;

determining a sensed pressure between the ultrasonic handpiece and the surgical implement based on the pressure signal;

comparing the sensed pressure between the ultrasonic handpiece and the surgical implement to a predetermined pressure range to determine if the sensed pressure is within the predetermined pressure range, the predetermined pressure range indicating that the sensed pressure between the ultrasonic handpiece and the surgical implement is ready for welding;

applying a first tuning signal to the ultrasonic handpiece only when the pressure between the ultrasonic handpiece and the surgical implement is determined to be within the predetermined pressure range, the first tuning signal having a first variable frequency within a predetermined frequency range between 19.5 kHz and 20.7 kHz;

detecting a first impedance and a second impedance of the ultrasonic handpiece in response to the first tuning signal;

comparing the first impedance to the second impedance;

applying a second tuning signal to the ultrasonic handpiece, the second tuning signal having a second variable frequency within the predetermined frequency range; and

causing vibratory energy to be transferred, when the pressure between the ultrasonic handpiece and the surgical implement has settled within the predetermined pressure range for at least a predetermined settling interval, through the ultrasonic handpiece to the surgical implement to form a weld at the surgical implement for stabilizing body tissue with the weld, wherein the predetermined settling interval is 2 seconds.

6. The surgical generator in accordance with claim 5 , wherein said comparing the first impedance to the second impedance comprises determining whether a difference between the first impedance and the second impedance is less than a predetermined threshold.

7. The surgical generator in accordance with claim 5 , wherein the functions performed by the processing device further comprise:

detecting a third impedance and a fourth impedance of the ultrasonic handpiece in response to the second tuning signal;

comparing the third impedance to the fourth impedance; and

applying a third tuning signal to the ultrasonic handpiece, the third tuning signal having a third variable frequency within the predetermined frequency range.

8. The surgical generator in accordance with claim 7 , wherein said comparing the third impedance to the fourth impedance comprises determining whether a difference between the third impedance and the fourth impedance is less than a predetermined threshold.

9. A system comprising:

a handpiece configured to generate vibratory energy, the handpiece comprising a pressure sensor adapted to produce a pressure signal indicative of a pressure between the handpiece and a surgical implement; and

a generator coupled to the handpiece, the generator comprising a processing device and a memory device having encoded thereon computer-readable instructions that are executable by the processing device to perform functions comprising:

receiving a pressure signal from the pressure sensor indicative of a pressure between the handpiece and a surgical implement disposed within a body of a patient;

determining a sensed pressure between the handpiece and the surgical implement based on the pressure signal;

comparing the sensed pressure between the handpiece and the surgical implement to a predetermined pressure range to determine if the sensed pressure is within the predetermined pressure range, the predetermined pressure range indicating that the sensed pressure between the handpiece and the surgical implement is ready for welding;

applying a first tuning signal to the handpiece only when the pressure between the handpiece and the surgical implement is determined to be within the predetermined pressure range, the first tuning signal having a first variable frequency within a predetermined frequency range between 19.5 kHz and 20.7 kHz;

detecting a first impedance and a second impedance of the handpiece in response to the first tuning signal;

comparing the first impedance to the second impedance;

applying a second tuning signal to the handpiece, the second tuning signal having a second variable frequency within the predetermined frequency range; and

transferring, when the pressure between the handpiece and the surgical implement has settled within the predetermined pressure range for at least a predetermined settling interval, vibratory energy through the handpiece to the surgical implement to form a weld at the surgical implement for stabilizing body tissue with the weld, wherein the predetermined settling interval is 2 seconds.

10. The system in accordance with claim 9 , wherein said comparing the first impedance to the second impedance comprises determining whether a difference between the first impedance and the second impedance is less than a predetermined threshold.

11. The system in accordance with claim 9 , wherein the functions performed by the processing device further comprise:

detecting a third impedance and a fourth impedance of the handpiece in response to the second tuning signal;

comparing the third impedance to the fourth impedance; and

applying a third tuning signal to the handpiece, the third tuning signal having a third variable frequency within the predetermined frequency range.

12. The system in accordance with claim 11 , wherein said comparing the third impedance to the fourth impedance comprises determining whether a difference between the third impedance and the fourth impedance is less than a predetermined threshold.

13. The method of claim 1 further comprising applying a resonance frequency to the ultrasonic handpiece to form a weld at the surgical implement.

14. The method of claim 5 further comprising applying a resonance frequency to the ultrasonic handpiece to form a weld at the surgical implement.

15. The method of claim 9 further comprising applying a resonance frequency to the ultrasonic handpiece to form a weld at the surgical implement.