Ultrasonic Transducer Geometry for Tip Excursion
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Solution Overview
Problem
Ultrasonic surgical instruments face limitations in maximizing the longitudinal excursion of the end effector tip and tolerating frequency errors in the energy source, which affects their performance and efficiency during surgical procedures.
Innovation Solution
The design of an ultrasonic surgical instrument system that includes a transducer configured to produce vibrations along a longitudinal axis, featuring a specific geometry with a proximal flange, cylindrical portions, a tapered portion, and a cylindrical mass, optimized to maximize displacement and phase margin, thereby enhancing the instrument's ability to handle frequency errors and improve surgical efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the ultrasonic transducer uses a conventional design, then the structure is simple, but the longitudinal excursion of the end effector tip is limited and frequency error tolerance is poor
Solution Approach 1:
The transducer structure is divided into multiple cylindrical portions (first cylindrical member, second cylindrical member) with different functions. The first cylindrical member contains the piezoelectric elements while the second cylindrical member serves as a mechanical amplifying structure, allowing each segment to be optimized independently for both simplicity and performance.
Solution Approach 2:
The patent introduces a mechanical vibration amplifying part that transforms the vibration amplitude in a different dimensional space. By using a lever-like mechanical amplification mechanism within the transducer structure, the longitudinal excursion is amplified without significantly increasing the overall structural complexity.
2Reliability
If the ultrasonic transducer uses a conventional design, then the manufacturing is straightforward, but the tolerance to frequency errors in the energy source is poor
Solution Approach 1:
The patent optimizes specific geometric parameters of the cylindrical members (diameters, lengths, positioning) to tune the mechanical resonance characteristics. By carefully selecting these parameters, the transducer achieves broader frequency tolerance while maintaining manufacturability through standard machining operations.
Solution Approach 2:
The mechanical vibration amplifying part is designed with inherent damping and compliance features that compensate for frequency variations before they affect the end effector performance. This pre-compensation mechanism provides tolerance to frequency errors without requiring complex active control systems.
3Productivity
If the end effector tip excursion is maximized, then more surgical work can be accomplished, but the transducer structure becomes more complex
Solution Approach 1:
The patent utilizes resonant mechanical vibration in the cylindrical members to amplify the endpoint excursion. By designing the transducer to operate at its natural resonant frequency, large amplitude vibrations are achieved with minimal input energy, maximizing surgical productivity without proportionally increasing structural complexity.
Solution Approach 2:
The mechanical vibration amplifying part serves multiple functions simultaneously: it amplifies vibration amplitude, provides mechanical coupling between piezoelectric elements and the output, and acts as a mechanical filter. This multi-functionality increases productivity while avoiding the need for separate components for each function.
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 optimized geometry of the ultrasonic surgical instrument system increases the displacement of the end effector tip and improves the instrument's tolerance to frequency errors, leading to enhanced performance and efficiency in surgical procedures, such as cutting and coagulation.
Implementation Method 1
The transducer may be constructed of one or more piezoelectric or magnetostrictive elements in the instrument hand piece. Vibrations generated by the transducer are transmitted to the surgical end effector
Implementation Method 2
The transducer may be constructed of one or more piezoelectric or magnetostrictive elements in the instrument hand piece
Implementation Method 3
Activating or exciting the end effector (e.g., cutting blade) of such instruments at ultrasonic frequencies induces longitudinal vibratory movement that generates localized heat within adjacent tissue
Implementation Method 4
The waveguide and end effector are designed to resonate at the same frequency as the transducer. Therefore, when an end effector is attached to a transducer, the overall system frequency is the same frequency as the transducer itself
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
In an aspect, an ultrasonic horn includes a proximal flange (210), a first cylindrical portion (220) having a first diameter and positioned distal to the proximal flange, a second cylindrical portion (230) including a second diameter and a distal end, in which the second cylindrical portion is at a position located distal to the first cylindrical portion and in which the second diameter is smaller than the first diameter, a tapered portion (242) disposed between the first cylindrical portion and the second cylindrical portion, and a cylindrical mass (260) disposed about the horn at a position located between the flange and the distal end of the second cylindrical portion. In another aspect, an ultrasonic system comprising an end-bell, an ultrasonic horn as disclosed above, a transducer portion disposed between the end-bell and the ultrasonic horn, and an ultrasonic power source to supply an electrical signal to actuate the transducer portion.