Ultrasonic Surgical Tool Assembly for Standing-Wave Energy Transfer
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Solution Overview
Problem
Existing ultrasonic surgical instruments face challenges in efficiently transmitting ultrasonic energy to surgical end effectors, particularly in minimally invasive procedures, due to the need for precise frequency matching and effective heat management during tissue cutting and coagulation.
Innovation Solution
The fabrication of ultrasonic surgical instruments involves machining a surgical tool from a flat metal stock, coupling transducers in a D31 mode to induce a standing wave, and using piezoelectric elements with conductive adhesives and thermal conductors to manage heat, ensuring efficient energy transmission and vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If ultrasonic transducers are used to transmit energy to surgical end effectors, then cutting and coagulation performance is improved, but heat generation in tissue increases
Solution Approach 1:
The patent applies local quality by creating asymmetric blade geometry with different cross-sectional areas at different locations. The blade has a larger cross-sectional area at the proximal end and a smaller cross-sectional area at the distal end, which distributes the ultrasonic energy transmission differently along the blade length. This geometric variation allows efficient energy transmission to the tissue-contacting distal end while reducing heat accumulation in that critical area.
Solution Approach 2:
The patent directly applies asymmetry by designing the ultrasonic blade with non-uniform cross-sectional geometry. The blade cross-section varies asymmetrically along its length, with the proximal portion having a larger area than the distal portion. This asymmetric design optimizes the distribution of mechanical stress and ultrasonic energy, enabling effective cutting and coagulation at the distal tip while managing heat generation through the varied geometry.
2Productivity
If transducers are coupled to induce standing waves, then vibration efficiency is improved, but frequency matching precision requirements increase
Solution Approach 1:
The patent applies universality by designing the blade geometry to serve multiple functions simultaneously. The asymmetric cross-sectional variation along the blade length not only optimizes vibration efficiency and standing wave induction but also provides inherent frequency matching characteristics. The specific geometric profile is designed to resonate at the desired ultrasonic frequency, reducing the stringency of external frequency matching requirements while maintaining high vibration efficiency.
3Power
If solid core ultrasonic instruments are used, then ultrasonic energy transmission is improved, but device complexity increases
Solution Approach 1:
The patent applies merging by integrating the ultrasonic blade directly with the waveguide structure in a solid core configuration. The blade and waveguide form a unified solid structure that transmits ultrasonic energy efficiently from the transducer through the waveguide to the blade tip. This merged design eliminates the need for separate hollow core components and complex assembly mechanisms, reducing overall device complexity while maintaining high power transmission 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
This method enhances the efficiency of ultrasonic energy transmission to surgical end effectors, improving cutting and coagulation performance while minimizing heat generation, suitable for both open and minimally invasive procedures.
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
AI summary
A method of fabricating an ultrasonic medical device is presented. The method includes machining a surgical tool from a flat metal stock, contacting a face of a first transducer with a first face of the surgical tool, and contacting a face of a second transducer with an opposing face of the surgical tool opposite the first transducer. The first and second transducers are configured to operate in a D31 mode with respect to the longitudinal portion of the surgical tool. Upon activation, the first transducer and the second transducer are configured to induce a standing wave in the surgical tool and the induced standing wave comprises a node at a node location in the surgical tool and an antinode at an antinode location in the surgical tool.