Ultrasonic Surgical Tool Drive Control for Harmonic Cancellation
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Solution Overview
Problem
Conventional ultrasonic surgical tools experience harmonic distortion due to harmonic signals causing variable phase shifts in the handpiece current and voltage, leading to unwanted vibrations, excessive heat, and reduced performance, which affects the tip's lifespan and tissue heating.
Innovation Solution
A console system that applies a first drive signal to the ultrasonic surgical tool, acquires characteristics of the harmonic signal, generates a cancellation signal, and combines it with the first drive signal to produce a second drive signal that is sinusoidal, thereby reducing the presence of harmonic signals and minimizing harmonic distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sinusoidal drive signal is applied to the ultrasonic surgical tool, then the tip operates at resonance with dominant longitudinal vibration mode, but harmonic distortion occurs causing variable phase shifts in current and voltage
Solution Approach 1:
The patent detects the harmonic distortion generated by the ultrasonic tip and converts this harmful effect into a useful cancellation signal. By generating an anti-phase signal at the harmonic frequency that matches the distortion amplitude, the system neutralizes the harmful harmonics while preserving the beneficial fundamental vibration mode for surgical operations
Solution Approach 2:
The system continuously monitors the electrical characteristics (current and voltage) of the ultrasonic handpiece to detect harmonic distortion in real-time. This feedback mechanism allows the control system to dynamically adjust the cancellation signal parameters, ensuring continuous suppression of harmonic distortion throughout the surgical procedure
2Productivity
If conventional ultrasonic tips are operated at high power, then tissue resection performance is improved, but excessive heat is generated reducing tip lifespan
Solution Approach 1:
The patent converts the harmful thermal energy that would otherwise be wasted as excessive heat into useful work by directing it toward cavitation bubble formation. The ultrasonic vibrations at the tip surface generate cavitation bubbles in the fluid medium, and the collapse of these bubbles produces localized mechanical effects that assist in tissue resection, thereby utilizing the thermal energy productively
Solution Approach 2:
The system changes the operational parameters of the ultrasonic tip by introducing controlled harmonic distortion and cavitation effects. By modulating the drive signal to include specific harmonic components and controlling the cavitation bubble dynamics, the system achieves enhanced tissue resection efficiency at lower overall power levels, reducing excessive heat generation
3Productivity
If the system operates at higher voltage to overcome loading effects from temperature increase, then tissue resection continues, but performance of the controlling console is reduced due to unwanted vibration energy feedback
Solution Approach 1:
The patent extracts the harmful vibration energy that would otherwise be reflected back to the console by using it to generate cancellation signals. The system detects the vibration characteristics and generates anti-phase signals that neutralize the reflected energy, effectively removing the harmful feedback before it reaches the console while maintaining continuous tissue resection capability
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
The system effectively reduces harmonic distortion, improving the surgical tool's performance by minimizing impedance, power requirements, and enhancing tissue resection capabilities while allowing control over multiple resonant modes.
Implementation Method 1
A tip (26) coupled to the transducer (24) to interface with tissue... The tip (26) operates at resonance when mechanical current is in phase with the handpiece voltage
Implementation Method 2
The tip (26) operates at resonance when mechanical current is in phase with the handpiece voltage
Implementation Method 3
The controller (30) generates a cancellation signal configured to reduce the harmonic signal... combines the first drive signal and the cancellation signal to produce a second drive signal
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
Systems (10) and methods (12) of controlling an ultrasonic surgical tool (20) with a console (22) are provided. A first drive signal (40) is applied to the ultrasonic surgical tool (20). A characteristic of a harmonic signal (44) resulting from application of the first drive signal (40) to the ultrasonic surgical tool (20) is acquired. A cancellation signal (70) is generated based on the characteristic of the harmonic signal (44). The first drive signal (40) and the cancellation signal (70) are combined to produce a second drive signal (80) that is sinusoidal. The second drive signal (80) is applied to the ultrasonic surgical tool (20) such that presence of the harmonic signal (44) resulting from application of the second drive signal (80) is reduced relative to presence of the harmonic signal (44) resulting from application of the first drive signal (40).