Microstructured Polymeric Coating for Medical Wire Friction Reduction
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Solution Overview
Problem
Medical devices, such as pacemaker leads and rotational atherectomy catheters, experience wear and friction issues due to constant movement, leading to isolation failure and potential short-circuiting or lubricant displacement, which can result in device failure.
Innovation Solution
A polymeric coating with flexible microstructures is applied to the outer surface of the medical device wires, extending outward to reduce friction and wear, and a protective coating with higher modulus of elasticity is applied to enhance durability, along with a lubricant between the device and wire to maintain lubrication and reduce abrasion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a smooth polymeric coating is applied to the wire surface, then the coating provides basic isolation and lubrication, but friction and wear increase over time due to constant movement
Solution Approach 1:
The patent applies a porous microstructure to the polymeric coating surface, creating micro-cavities and channels that trap lubricant. This porous structure reduces direct contact between the wire and catheter inner surface, thereby reducing friction and wear while maintaining isolation durability throughout the device lifetime
Solution Approach 2:
The patent creates localized regions with different properties by forming a microstructured surface layer on the polymeric coating. The microstructure provides localized lubricant retention zones with high lubrication capacity, while the bulk coating maintains its isolation properties, achieving both reduced friction and durable isolation
2Strength
If a hard protective coating is applied to reduce wear, then durability improves, but friction increases due to higher modulus of elasticity
Solution Approach 1:
The patent creates a composite structure combining a soft polymeric coating bulk with a harder microstructured surface layer. The bulk material provides flexibility and lubricant retention, while the microstructured surface layer provides wear resistance. This composite approach reduces friction through lubricant trapping while maintaining high wear resistance
Solution Approach 2:
The patent uses a flexible polymeric coating as the base layer that can deform and conform to the wire surface. The flexible nature of the bulk coating allows it to maintain contact with the wire while the microstructured surface provides the protective function, reducing both friction and wear simultaneously
3Force
If lubricant is applied between the catheter and drive shaft, then friction is reduced, but lubricant is pushed out when the catheter curves, leading to loss of lubrication
Solution Approach 1:
The porous microstructure on the polymeric coating surface acts as a lubricant reservoir, trapping and retaining lubricant within the micro-cavities. When the catheter curves and compression forces are applied, the lubricant is retained within the porous structure rather than being pushed out, maintaining continuous lubrication and reducing friction
Solution Approach 2:
The microstructured polymeric coating provides self-lubrication by retaining lubricant within its structure. The coating itself serves as the lubricant delivery system, eliminating the need for external lubricant application and ensuring continuous lubrication throughout device operation without lubricant loss
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 polymeric coating with microstructures effectively reduces wear and friction, preventing isolation failure and maintaining lubrication, thereby enhancing the longevity and performance of medical devices by minimizing contact surface area and retaining lubricant, thus preventing device failure.
Implementation Method 1
A lubricant including saline may flow between the catheter and the drive shaft
Implementation Method 2
a protective coating with higher modulus of elasticity is applied to enhance durability
Data Source
AI summary
A medical device includes a tubular body having a distal end and a proximal end, a lumen extending through the tubular body from the distal end to the proximal end, a wire extending through the lumen from the distal end to the proximal end, and a polymeric coating. The wire has an outer surface. The polymeric coating is on at least a portion of the outer surface of the wire. The coating comprises a bulk material and a plurality of flexible microstructures disposed on the bulk material. The microstructures extend outwardly from a surface of the polymeric coating.