Ultrasonic End Effector State Detection Using Impedance Sweep
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Solution Overview
Problem
Ultrasonic and electrosurgical devices require different generators due to their unique drive signals, sensing, and feedback needs, leading to limitations in recognizing instrument configurations and optimizing control and diagnostic processes, especially when instruments are disposable or interchangeable, and resulting in potential patient exposure to leakage currents.
Innovation Solution
An ultrasonic device with an electromechanical system that includes an ultrasonic transducer coupled to an ultrasonic blade, using a drive circuit to apply a periodic drive signal with adjustable frequency, and a processor to measure and compare impedance/admittance circle variables to determine the state of the end effector, allowing for adaptive control and feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate generators are used for ultrasonic and electrosurgical devices, then each device can have optimized drive signals and control, but the system complexity increases and adaptability to interchangeable instruments decreases
Solution Approach 1:
The patent implements a single generator capable of providing both ultrasonic and electrosurgical energy through a unified control system. The generator uses a single impedance sensing circuit and control algorithm that can identify instrument type and automatically adjust parameters, eliminating the need for separate generators while maintaining optimized performance for both ultrasonic and electrosurgical instruments.
Solution Approach 2:
The control system dynamically adapts its operation based on real-time impedance measurements and instrument identification. The generator transitions between ultrasonic and electrosurgical modes by adjusting drive signal characteristics according to the connected instrument, enabling a single static device to perform multiple functions through dynamic parameter changes.
2Adaptability or versatility
If a single generator is used for both ultrasonic and electrosurgical devices, then system complexity is reduced and adaptability improves, but measurement precision and control accuracy may deteriorate due to different drive signal requirements
Solution Approach 1:
The patent employs continuous impedance sensing and feedback control to maintain measurement precision across different instrument types. The system measures impedance in real-time, compares it against reference values to identify instrument configuration, and adjusts control parameters accordingly. This closed-loop feedback ensures accurate measurements and optimal control regardless of whether ultrasonic or electrosurgical instruments are connected.
Solution Approach 2:
The generator changes operational parameters including drive signal frequency, amplitude, and waveform characteristics based on the identified instrument type. For ultrasonic instruments, it uses high-frequency sinusoidal drive signals, while for electrosurgical instruments, it employs different waveform patterns, thereby maintaining measurement precision and control accuracy across diverse instrument configurations.
3Ease of operation
If disposable or interchangeable instruments are used, then ease of operation and sterility are improved, but the ability to recognize instrument configuration and optimize control processes is reduced
Solution Approach 1:
The system automatically identifies and adapts to the connected instrument without requiring manual configuration or programming. When an interchangeable instrument is connected, the generator performs automated impedance sensing and instrument identification, then self-adjusts control parameters optimally for that specific instrument type, eliminating the need for user intervention while maintaining full control optimization.
4Reliability
If electromagnetic interference filtering is increased to maintain frequency lock in noisy environments, then reliability is improved, but the response time and productivity of the control system may decrease
Solution Approach 1:
The system performs preliminary impedance characterization and instrument identification during the startup phase or when instruments are connected, before critical surgical operations begin. This advance preparation allows the control system to have instrument-specific parameters pre-loaded and ready, reducing the need for continuous adjustments during operation while maintaining reliable frequency lock even in noisy electromagnetic environments.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate determination of the end effector's state and adaptive control, improving precision and safety by reducing leakage currents and optimizing control processes for both ultrasonic and electrosurgical instruments.
Implementation Method 1
Vibrating at high frequencies (e.g., 55,500 cycles per second), the ultrasonic blade denatures protein in the tissue to form a sticky coagulum
Implementation Method 2
An ultrasonic surgical device may comprise a handpiece containing an ultrasonic transducer
Implementation Method 3
measuring and recording impedance/admittance circle variables
Data Source
AI summary
An ultrasonic device may include an electromechanical ultrasonic system defined by a predetermined resonant frequency, in which the system may include an ultrasonic transducer coupled to an ultrasonic blade. A method of estimating a state of an end effector of the ultrasonic device may include applying a drive signal defined by a magnitude and a frequency to the ultrasonic transducer, sweeping the frequency of the drive signal from below a first resonance to above the first resonance of the electromagnetic ultrasonic system, measuring and recording, impedance/admittance circle variables Re, Ge, Xe, and Be, comparing, the measured impedance/admittance circle variables Re, Ge, Xe, and Be to reference impedance/admittance circle variables Rref, Gref, Xref, and Bref, and determining, a state or condition of the end effector based on the result of the comparison. An electromechanical ultrasonic system may include a control circuit to effect the method.