Stent Coating Apparatus with Image-Guided Dispensing
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Solution Overview
Problem
Existing stent coating methods often result in imperfections such as bridging, meniscus, and overhang, which can lead to coating breakage and potential blood clotting issues during stent expansion, and fail to achieve a uniform and precise application of drug-containing coatings on both outer and side surfaces.
Innovation Solution
A coating apparatus and method that uses a computer-controlled dispensing system with image processing algorithms to determine traversal paths and dispensing speeds, ensuring precise application of coating material to the outer and side surfaces of stents, minimizing imperfections and achieving a selected ratio of side to outer surface coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional coating methods (soaking, dipping, spraying) are used, then the coating process is simple and fast, but the coating covers both inner and outer surfaces leading to unwanted drug effects at the interior surface and potential cracking during stent removal
Solution Approach 1:
The patent applies local quality by selectively coating only the outer surface of the stent while avoiding the inner surface. The dispensing head is positioned and controlled to deposit coating material precisely on the outer surface, ensuring that the interior surface remains uncoated and free from unwanted drug effects.
Solution Approach 2:
The patent replaces conventional mechanical coating methods (soaking, dipping, spraying) with a computer-controlled dispensing system. This substitution allows for precise control of coating application, enabling selective outer surface coating while eliminating the problems associated with conventional methods that cannot distinguish between inner and outer surfaces.
2Manufacturing precision
If micropipetting is used for coating, then selective application is possible, but coating imperfections such as bridging and meniscus occur which can break during stent expansion
Solution Approach 1:
The patent replaces micropipetting with a computer-controlled dispensing head that uses algorithms to determine traversal paths and dispensing speeds. This substitution eliminates manual positioning errors and ensures consistent, controlled coating application that avoids imperfections like bridging and meniscus formation.
Solution Approach 2:
The patent incorporates feedback mechanisms through computer control that monitors and adjusts dispensing parameters in real-time. The system uses algorithms to calculate optimal traversal paths and speeds based on stent geometry, ensuring uniform coating thickness and preventing the formation of imperfections that could compromise coating integrity during expansion.
3Productivity
If faster dispensing is used to increase productivity, then coating uniformity and precision decrease, but slower dispensing ensures better coating quality
Solution Approach 1:
The patent applies dynamics by making the dispensing speed variable rather than constant. The computer-controlled system adjusts dispensing speed dynamically based on the local geometry of the stent, using algorithms to calculate optimal speeds that maintain coating uniformity while maximizing overall productivity. This allows faster dispensing in suitable areas while slowing down where precision is critical.
Solution Approach 2:
The system uses feedback control to monitor coating application in real-time and adjust dispensing parameters accordingly. The computer-controlled dispensing head responds to geometric information about the stent surface, automatically modulating speed to maintain optimal coating quality across different regions while maintaining high overall productivity.
Data Source
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AI summary
An automated apparatus and method for coating medical devices such as an intravascular stent, are disclosed in the method, a 2-D image of a stent is processed to determine (1 ) paths along the stent skeletal elements by which a stent secured to a rotating support element can be traversed by a dispenser head whose relative motion with respect to the support element is along the support-element axis, such that some or all of the stent skeletal elements will be traversed (2) the relative speeds of the dispenser head and support element as the dispenser head travels along the paths, and (3), and positions of the dispenser head with respect to a centerline of the stent elements as the dispenser head travels along such paths The rotational speed of the support and relative linear speed of the dispenser are controlled to achieve the desired coating thickness and coating coverage on the upper surfaces, and optionally, the side surfaces, of the stent elements