Sonotrode Node Cross-Section for Ultrasonic Friction Reduction
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Solution Overview
Problem
In ultrasonic systems, particularly in minimally invasive surgery, slender and long sonotrodes with limited bending strength face challenges in efficient vibrational energy transmission and low friction within guide shafts, leading to energy loss, heat generation, and potential tissue damage from wear debris.
Innovation Solution
The sonotrode design features a minimal radial clearance at the most distal node position with an increased cross section, a constant guide shaft cross section extending beyond this node, and a friction-reducing coating, along with a softer material ring at the distal end to minimize friction and wear, ensuring efficient energy transmission and reduced wear debris.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the sonotrode is made slender and long to reach deep tissue targets, then the access path is extended, but the bending strength is reduced and friction in the guide shaft increases
Solution Approach 1:
The sonotrode is segmented into different cross-sectional regions: a first region with larger cross-section for strength, a second region with reduced cross-section for flexibility and node positioning, and a third region with increased cross-section at the node for friction reduction. This segmentation allows the sonotrode to simultaneously achieve the required length, maintain bending strength, and reduce friction in the guide shaft.
2Length of moving object
If the sonotrode extends through a large portion of the guide shaft, then deep tissue access is enabled, but friction and energy loss increase
Solution Approach 1:
The sonotrode features local quality variations with different cross-sectional areas at different positions. Specifically, the third region has an increased cross-section at the node position where it contacts the guide shaft, creating a localized friction-reducing feature that minimizes energy loss during the extended traversal through the guide shaft while maintaining overall sonotrode functionality.
3Loss of energy
If the radial clearance between sonotrode and guide shaft is reduced, then friction is minimized, but manufacturing precision requirements increase
Solution Approach 1:
The invention changes the geometric parameter of the sonotrode by providing regions with different cross-sectional areas. The third region specifically has an increased cross-section that reduces radial clearance with the guide shaft, thereby minimizing friction. This parameter change approach allows for controlled friction reduction while maintaining feasible manufacturing precision requirements.
4Length of moving object
If the sonotrode is made longer to reach deep targets, then treatment depth is increased, but heat generation from friction increases
Solution Approach 1:
The sonotrode incorporates a third region with increased cross-section at the node position where contact with the guide shaft occurs. This local quality enhancement reduces friction at the critical contact point, thereby minimizing heat generation from friction during the extended traversal through the guide shaft, even as the overall sonotrode length increases for deep tissue access.
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 configuration enhances energy transmission efficiency, reduces friction and heat generation, and prolongs system lifespan by minimizing wear debris, which is critical in medical applications where tissue integrity must be maintained.
Implementation Method 1
a sonotrode (1) with a distal end (1.1) and a proximal end (1.2), wherein the proximal end (1.2) is coupled to a vibration source (not shown) to vibrate the distal end (1.1) in a stationary wave with anti-node positions (positions with maximum amplitude) at both ends
Implementation Method 2
a friction-reducing coating, along with a softer material ring at the distal end to minimize friction and wear
Data Source
AI summary
A system to be used for transmitting ultrasonic vibration, the system including a sonotrode designed to vibrate in a stationary wave having at least one node position between the distal end and the proximal end of the sonotrode, and a guide shaft with a through opening. During operation the sonotrode extends through the through opening of the guide shaft and the distal end of the guide shaft is situated on a distal side of the most distal node position of the sonotrode. The sonotrode and the guide shaft are adapted to each other for radial clearance between the sonotrode and the guide shaft to be a minimum for a sonotrode portion comprising the most distal node position.