Adjustment of complex impedance to compensate for lost power in an articulating ultrasonic device

Patent metadata

Field	Value
Publication number	US-11986233-B2
Application number	US-201816144418-A
Country	US
Kind code	B2
Filing date	Sep 27, 2018
Priority date	Mar 8, 2018
Publication date	May 21, 2024
Grant date	May 21, 2024

Abstract

An ultrasonic device may include an electromechanical ultrasonic system defined by a predetermined resonant frequency, the electromechanical ultrasonic system having an ultrasonic transducer coupled to an ultrasonic blade. A method of compensating power delivered to the ultrasonic device may include determining an articulation angle of an articulatable ultrasonic blade coupled to the ultrasonic transducer, adjusting a complex impedance of the ultrasonic transducer to compensate for power lost as a function of the articulation angle, and adjusting, a power applied to the ultrasonic transducer based on the articulation angle. The ultrasonic device may include a generator and a control circuit configured to effect the method.

First claim

The invention claimed is:

1. An ultrasonic surgical instrument comprising:
an ultrasonic electromechanical system comprising an ultrasonic transducer coupled to an articulatable ultrasonic blade via a flexible ultrasonic waveguide; and
a generator to supply power to the ultrasonic transducer, wherein the generator comprises a control circuit configured to:
sweep the articulatable ultrasonic blade through a range of articulation angles from a first articulation angle to a second articulation angle at one or more predetermined angular increments;
activate the ultrasonic transducer at an energy level at each of the one or more predetermined angular increments;
measure a complex impedance of the ultrasonic transducer at each of the one or more predetermined angular increments;
record a set of complex impedance measurements at each of the one or more predetermined angular increments;
generate reference complex impedance characteristic patterns as a function of the one or more predetermined angular increments;
store the reference complex impedance characteristic patterns in a memory or a database;
determine a third articulation angle of the articulatable ultrasonic blade;
adjust the complex impedance of the ultrasonic transducer to compensate for power lost as a function of the one or more predetermined angular increments; and
adjust a power applied to the ultrasonic transducer based on the third articulation angle.

2. The ultrasonic surgical instrument of claim 1 , wherein the control circuit is configured to:
measure the complex impedance of the ultrasonic transducer, wherein the complex impedance is defined as

Z
g

⁡

(
t
)

=

V
g

⁡

(
t
)

I
g

⁡

(
t
)

;

receive a complex impedance measurement data point;
compare the complex impedance measurement data point to a data point in the reference complex impedance characteristic patterns;
classify the complex impedance measurement data point based on a result of the comparison; and
assign an articulation angle of the articulatable ultrasonic blade based on the result of the comparison.

3. The ultrasonic surgical instrument of claim 2 , wherein the control circuit is configured to compare the complex impedance measurement data point to a data point in the reference complex impedance characteristic pattern corresponding to one of the one or more predetermined angular increments.

4. The ultrasonic surgical instrument of claim 1 , wherein the control circuit is configured to:
cause a drive circuit to apply a drive signal to the ultrasonic transducer, wherein the drive signal is a periodic signal defined by a magnitude and frequency;
sweep the frequency of the drive signal from below resonance to above resonance of the ultrasonic electromechanical system;
measure and record impedance/admittance circle variables R e , G e , X e , and B e ;
compare measured impedance/admittance circle variables R e , G e , X e , and B e to reference impedance/admittance circle variables R ref , G ref , X ref , and B ref ; and
determine an articulation angle of the articulatable ultrasonic blade based on the result of the comparison.

5. The ultrasonic surgical instrument of claim 4 , wherein the control circuit is configured to compare the measured impedance/admittance circle variables R e , G e , X e , and B e to reference impedance/admittance circle variables R ref , G ref , X ref , and B ref corresponding to the articulation angle.

6. The ultrasonic surgical instrument of claim 1 , wherein the control circuit is configured to activate the ultrasonic transducer at a therapeutic or a non-therapeutic energy level.

7. The ultrasonic surgical instrument of claim 1 , wherein the memory or the database is accessible by the ultrasonic surgical instrument during a surgical procedure.

8. A generator for an ultrasonic surgical instrument, the generator comprising:
a control circuit configured to:
sweep an articulatable ultrasonic blade through a range of articulation angles from a first articulation angle to a second articulation angle at one or more predetermined angular increments;
activate an ultrasonic transducer at an energy level at each of the one or more predetermined angular increments;
measure a complex impedance of the ultrasonic transducer at each of the one or more predetermined angular increments;
record a set of complex impedance measurements at each of the one or more predetermined angular increments;
generate reference complex impedance characteristic patterns as a function of the one or more predetermined angular increments;
store the reference complex impedance characteristic patterns in a memory or database;
determine a third articulation angle of the articulatable ultrasonic blade coupled to the ultrasonic transducer via a flexible waveguide;
adjust the complex impedance of the ultrasonic transducer to compensate for power lost as a function of the third articulation angle; and
adjust a power applied to the ultrasonic transducer based on the third articulation angle.

9. The generator for an ultrasonic surgical instrument of claim 8 , wherein the control circuit is configured to:
measure the complex impedance of the ultrasonic transducer, wherein the complex impedance is defined as

Z
g

⁡

(
t
)

=

V
g

⁡

(
t
)

I
g

⁡

(
t
)

;

receive a complex impedance measurement data point;
compare the complex impedance measurement data point to a data point in the reference complex impedance characteristic patterns;
classify the complex impedance measurement data point based on a result of the comparison; and
assign one of the predetermined angular increments of the articulatable ultrasonic blade to the complex impedance measurement data point based on the result of the comparison.

10. The

Assignees

• Cilag Gmbh Int

Inventors

• Rockman Maxwell T
• Bishop Gregory D

Classifications

• A61B18/1206 Primary

  Generators therefor · CPC title

• A61B8/4483

  characterised by features of the ultrasound transducer · CPC title

• A61B8/56

  Details of data transmission or power supply · CPC title

• A61B17/00234

  for minimally invasive surgery (A61B17/0218, A61B17/0469, A61B17/12013, A61B17/1285, A61B17/29, A61B17/320016 take precedence) · CPC title

• A61B17/320068

  using mechanical vibrations, e.g. ultrasonic (A61B17/22012 takes precedence; dental tooth drilling devices operated by vibration A61C3/03; removing intra-ocular material using mechanical vibrations A61F9/00745) · CPC title