Cordless hand-held ultrasonic cautery cutting device
An ultrasonic surgical assembly includes an ultrasonic transducer operable to convert a received motional current into a movement of a cutting blade of an ultrasonic waveguide, a measurement circuit connected in a parallel configuration with the ultrasonic transducer, a variable power source operable to supply current through a set of connection points to the parallel configuration and thereby create the motional current in the ultrasonic transducer, and a current controller operable to regulate the motional current by varying an output of the variable power source, thereby maintaining a substantially constant rate of movement of the cutting blade across a variety of cutting loads.
1. An ultrasonic surgical assembly, comprising:
a surgical instrument handle, the handle having within it:
an ultrasonic transducer operable to convert a received motional current into a movement of a cutting blade of an ultrasonic waveguide;
a measurement circuit connected in a parallel configuration with the ultrasonic transducer;
a variable power source comprising a battery and operable to supply current through a set of connection points to the parallel configuration and thereby create the motional current in the ultrasonic transducer;
a current controller operable to regulate the motional current by varying an output of the variable power source, thereby maintaining a resonant condition along the cutting blade in which there is a substantially constant rate of movement of the cutting blade across a variety of cutting loads; and
a clamping mechanism having a range of clamping force values and being operable to place material in physical contact with the cutting blade, the current controller communicatively coupled to the clamping mechanism and operable to vary the motional current based upon a given clamping value within the range of clamping values.
2. The ultrasonic surgical assembly according to claim 1 , wherein:
the ultrasonic transducer has a first capacitance in a parallel configuration with a series configuration of a resistance, an inductance, and a second capacitance; and
the motional current flows through the series configuration.
3. The ultrasonic surgical assembly according to claim 2 , wherein the measurement circuit is comprised of a third capacitance in a parallel configuration with the first capacitance.
4. The ultrasonic surgical assembly according to claim 3 , wherein the variable power source is coupled to the third capacitance and the ultrasonic transducer.
5. The ultrasonic surgical assembly according to claim 4 , wherein the current controller is operable to regulate the motional current by varying an output of the variable power source based upon a product of the current flowing through the third capacitance multiplied by a ratio between a value of the first capacitance and a value of the third capacitance subtracted from a total current flowing into the ultrasonic transducer.
6. The ultrasonic surgical assembly according to claim 1 , wherein:
the current controller comprises a processor; and
the variable power source comprises a phase locked loop communicatively coupled to the processor and operable to determine a frequency of movement of the cutting blade; and
further comprising a memory communicatively coupled to the processor and operable to store a last frequency of blade movement.
7. The ultrasonic surgical assembly according to claim 1 , wherein the variable power source comprises a removable battery.
8. The ultrasonic surgical assembly according to claim 1 , further comprising a disposable handle body having:
a portion defining a battery-holding compartment having at least two battery contacts;
a waveguide attachment dock exposed to the environment and shaped to accept the ultrasonic waveguide therein;
a transducer attachment dock exposed to the environment and shaped to place the ultrasonic transducer in coaxial alignment with the ultrasonic waveguide when the ultrasonic waveguide is disposed within the waveguide attachment dock; and
an ultrasonic-signal-generator assembly dock exposed to the environment and shaped to substantially simultaneously:
selectively removably secure at least the ultrasonic transducer to the handle body;
place an end of the ultrasonic transducer within the transducer attachment dock; and
electrically couple at least the ultrasonic transducer to the at least two battery contacts.
9. An ultrasonic surgical assembly, comprising:
a surgical instrument handle, the handle having within it:
an ultrasonic transducer operable to convert a received motional current into a movement of a cutting blade of an ultrasonic waveguide, the ultrasonic transducer comprised of a first capacitance in a parallel configuration with a series configuration of a resistance, an inductance, and a second capacitance, whereby the motional current flows through the series configuration;
a measurement circuit connected in a parallel configuration with the ultrasonic transducer, the measurement circuit comprised of a third capacitance in a parallel configuration with the first capacitance;
a variable power source comprising a removable battery and operable to supply current through a set of connection points to the parallel configuration and thereby create the motional current in the ultrasonic transducer, wherein the variable power source is coupled to the third capacitance and the ultrasonic transducer; and
a current controller operable to regulate the motional current by varying an output of the variable power source based upon a product of the current flowing through the third capacitance multiplied by a ratio between a value of the first capacitance and a value of the third capacitance subtracted from a total current flowing into the ultrasonic transducer, thereby maintaining a resonant condition along the cutting blade in which there is a substantially constant rate of movement of the cutting blade across a variety of cutting loads.
10. The ultrasonic surgical assembly according to claim 9 , wherein:
the current controller comprises a processor; and
the variable power source comprises a phase locked loop communicatively coupled to the processor and operable to determine a frequency of movement of the cutting blade; and
further comprising a memory communicatively coupled to the processor and operable to store a last frequency of blade movement.
11. The ultrasonic surgical assembly according to claim 9 , further comprising a clamping mechanism having a range of clamping force values and being operable to place material in physical contact with the cutting blade, the current controller communicatively coupled to the clamping mechanism and operable to vary the motional current based upon a given clamping value within the range of clamping values.