Rollable Drive Shaft Structure for Guidewire Friction Reduction
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Solution Overview
Problem
Existing flexible drive shafts in rotational atherectomy devices cause excessive friction with guidewires, leading to wear, thermal melting, or uncoiling, making them unsuitable for commonly used clinical guidewires and increasing surgical costs.
Innovation Solution
A drive shaft design featuring a rollable inner layer with rollers that transitions friction from sliding to rolling, allowing the drive shaft to be compatible with standard clinical guidewires, reducing wear and tear, and incorporating features like slits for fluid flow to further reduce friction and heat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a flexible drive shaft is used to drive high-speed spinning of the burr, then the burr can effectively ablate calcified plaque, but excessive friction between the drive shaft and guidewire causes wear, thermal melting, or uncoiling of the guidewire
Solution Approach 1:
The patent introduces a PTFE coating on the drive shaft surface as an intermediary layer between the drive shaft and guidewire. This coating acts as a mediator that reduces direct contact friction, preventing guidewire damage while maintaining the high-speed rotation capability of the burr. The PTFE coating specifically addresses the friction problem without compromising the drive shaft's rotational function.
Solution Approach 2:
The patent changes the surface friction parameter of the drive shaft by applying a PTFE coating with low friction coefficient. This parameter change reduces the coefficient of friction between the drive shaft and guidewire, allowing high-speed rotation to proceed without generating excessive frictional heat or mechanical wear that would damage the guidewire.
2Reliability
If special guidewires without surface coating or coiled section are used to avoid friction damage, then guidewire failure is reduced, but surgical operability decreases and costs increase
Solution Approach 1:
By introducing the PTFE coating as an intermediary, the patent enables the use of standard guidewires with coatings and coiled sections that would otherwise be damaged by friction. The coating mediates the interaction, preserving both guidewire integrity and the full operational capabilities including compliance and pushing ability that these standard guidewires provide.
Solution Approach 2:
The PTFE coating acts as a sacrificial, low-cost protective layer on the drive shaft that prevents damage to more expensive and functionally critical guidewires. Instead of requiring expensive special guidewires, the system uses a disposable-like coating that can be applied to the drive shaft, reducing overall surgical costs while maintaining guidewire reliability.
3Object-affected harmful factors
If the drive shaft surface is modified to reduce friction, then guidewire wear is prevented, but the drive shaft structure becomes more complex
Solution Approach 1:
The patent modifies the surface parameter of the existing drive shaft structure by applying a PTFE coating, rather than redesigning the entire drive shaft architecture. This parameter change approach reduces friction and heat generation while maintaining the original simple structural design of the drive shaft, avoiding increased device complexity.
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 solution effectively reduces friction and the risk of guidewire failure, enabling the use of standard clinical guidewires, improving surgical operability and lowering costs while maintaining high-speed rotation capabilities.
Implementation Method 1
the inner layer is rollable relative to both the outer layer and the guidewire and thus allows rolling friction to occur between the drive shaft and the guidewire
Implementation Method 2
incorporating features like slits for fluid flow to further reduce friction and heat
Data Source
Figure 1~3
Figure 4~6
Figure 7~8
AI summary
A drive shaft (1, 3) for use with a rotation device (10, 20) includes an outer layer (11, 31) and an inner layer (12, 32). The outer layer is a tubular structure, and the inner layer is accommodated in a space defined by the outer layer and defines a central lumen (13, 33) for receiving therein an external mechanism. The outer layer is rotatable about the central lumen, and the inner layer is rollable relative to both the outer layer and the external mechanism and thus allows rolling friction to occur between the drive shaft and the external mechanism. Such a structure of the drive shaft can reduce friction between the drive shaft and a guidewire as well as loss due to such friction, avoiding failure of the guidewire due to excessive friction between the guidewire and the drive shaft. Therefore, it is ensured that the drive shaft is suitable for use with guidewires commonly used in clinical practice, resulting in improved surgical operability and lower surgical cost. Also disclosed is a rotation device including an instrument (2, 4) and the drive shaft. The instrument is disposed at one end of the drive shaft and is coupled to the outer layer of the drive shaft so as to be able to be driven by the outer layer to rotate.