Composite Ultrasonic End Effector for Extended Wavelength
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Solution Overview
Problem
Current ultrasonic surgical instruments face challenges in providing end effectors with a longer ultrasonic propagation wavelength and greater fatigue strength while maintaining acoustic efficiency and thermal characteristics, with limited material choices available for specific surgical applications.
Innovation Solution
The development of a composite ultrasonic end effector formed from a combination of materials, such as a titanium alloy for structural toughness and a ceramic or aluminum alloy for enhanced acoustic properties, allowing for a longer effective length and improved mechanical fatigue strength, along with controlled heat transfer and acoustic transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the frequency of ultrasonic energy input is decreased to increase the propagation wavelength, then the end effector length increases, but the audible sound becomes painfully loud and the surgical application becomes impractical
Solution Approach 1:
The patent changes the material parameter (elastic modulus to density ratio) rather than the operational parameter (frequency) to achieve the desired wavelength increase. By selecting materials with higher elastic modulus to density ratios, the ultrasonic propagation wavelength increases without changing the operating frequency, thus avoiding audible sound while achieving longer end effector effective length.
Solution Approach 2:
The patent employs composite materials or materials with superior elastic modulus to density ratios (such as certain ceramics or metal alloys) to construct the end effector. These materials inherently provide longer ultrasonic propagation wavelengths at the same operating frequency, enabling longer end effector design without producing painfully audible sounds.
2Length of moving object
If ceramic materials are selected to achieve longer ultrasonic propagation wavelengths, then the wavelength increases, but the material becomes susceptible to breakage during handling and operation
Solution Approach 1:
The patent uses composite material construction where a ceramic or high elastic modulus material forms the core or active ultrasonic transmission element, while a tougher material (such as metal alloy) provides structural support and protection. This composite approach allows the end effector to achieve long ultrasonic propagation wavelengths while maintaining resistance to breakage during handling and surgical operation.
Solution Approach 2:
The end effector is divided into functional segments: an inner core or portion made of ceramic/high elastic modulus material for optimal ultrasonic wavelength transmission, and an outer structural portion made of tougher material for mechanical protection. This segmentation allows each material to perform its optimal function without compromising the other.
3Length of moving object
If materials with high elastic modulus to density ratio are used to increase propagation wavelength, then the wavelength increases, but the acoustic transmission efficiency and self-heating characteristics may become suboptimal for certain surgical applications
Solution Approach 1:
The patent employs composite material construction where materials are selected and combined to achieve both long ultrasonic propagation wavelengths and high acoustic transmission efficiency. The composite structure allows optimization of the elastic modulus to density ratio for wavelength while selecting materials with appropriate Q coefficients for efficient energy transmission and controlled self-heating characteristics.
Solution Approach 2:
Different portions of the end effector may use different materials or material properties optimized for specific functions: the ultrasonic transmission path uses materials with high elastic modulus to density ratio for long wavelength, while surface layers or specific zones use materials optimized for acoustic efficiency and heat management to ensure optimal surgical performance.
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
This composite approach enables the creation of end effectors that can effectively cut and coagulate tissue with improved durability and efficiency, addressing the limitations of single-material end effectors by optimizing acoustic and thermal properties.
Implementation Method 1
Piezoelectric elements are electrically excited at a resonant frequency of an ultrasonic instrument to create vibrations
Implementation Method 2
create vibrations that are transmitted through a resonator and amplified to produce a mechanical, standing wave vibration of the same frequency
Implementation Method 3
The end effector may vibrate primarily in the longitudinal direction to generate localized heat within adjacent tissue
Data Source
Figure 1
Figure 2A~3
Figure 4
AI summary
An ultrasonic surgical system includes an ultrasonic transmission member having a proximal end and a distal end. An ultrasonically actuated end-effector is attached at the distal end of the transmission member. A pressurized fluid delivery system includes a fluid nozzle in communication with at least one fluid source. The fluid nozzle is arranged and configured to deliver pressurized fluid to soft tissue at a rate to move the soft tissue away from the end-effector during use.