Implantable Device Surface Texture Segmentation for Anchoring and Retrieval
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Solution Overview
Problem
Implantable cardiac pacemakers face challenges in maintaining effective anchoring and facilitating future removal or repositioning, with existing devices struggling to balance endothelial cell growth for anchoring and minimizing growth to allow for potential retrieval.
Innovation Solution
The design incorporates a housing with distinct surface textures for endothelial cell promotion and discouragement, featuring a fixation element for anchoring and a retrieval element, with an insulative layer that emulates these textures to control cell growth and facilitate device removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the outer housing surface has a uniform rough texture to promote endothelial cell growth for anchoring, then anchoring strength is improved, but device retrieval becomes difficult
Solution Approach 1:
The outer housing surface is divided into multiple regions with different surface textures. The first region has a rough texture that promotes endothelial cell growth for anchoring, while the second region has a smooth texture that discourages cell growth to facilitate retrieval. This segmentation allows different portions of the device to serve opposite functions.
Solution Approach 2:
Different regions of the outer housing surface are given different local properties: the first region is designed with roughness to encourage endothelialization and anchoring, while the second region is designed with smoothness to prevent endothelialization and enable future retrieval. Each region's surface texture is optimized for its specific function.
2Ease of operation
If the outer housing surface is made smooth to facilitate device removal, then device retrieval becomes easy, but anchoring strength is reduced
Solution Approach 1:
The housing surface is segmented into functional zones where one zone provides roughness for anchoring and another zone provides smoothness for retrieval. This allows the device to achieve both strong anchoring during operation and easy retrieval when needed.
Solution Approach 2:
The smooth surface region is strategically placed to provide local quality of low endothelial cell adhesion, while the rough surface region provides local quality of high endothelial cell adhesion. This local differentiation resolves the contradiction between anchoring and retrieval.
3Ease of manufacture
If the insulative layer has a uniform surface texture, then manufacturing is simplified, but endothelial cell growth control is reduced
Solution Approach 1:
The insulative layer is designed with spatially varying surface properties, where different regions have different roughness characteristics. This allows the layer to control endothelial cell growth differently across its surface while still being manufacturable through techniques like selective polishing or coating.
Solution Approach 2:
The insulative layer's outer surface emulates the underlying housing surface texture patterns, transferring the rough/smooth regional differentiation to the insulative layer without requiring a completely separate manufacturing process. The insulative layer copies the functional surface topology.
Data Source
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AI summary
An implantable medical device has a housing with a fixation element disposed adjacent a first end of the housing and a retrieval element disposed adjacent a second end of the housing. An outer housing surface includes a first region having a first surface texture with a first average surface roughness and a second region having a second surface texture with a second average surface roughness that is different from the first average surface roughness. An insulative layer includes a first region overlying the first surface texture and a second region overlying the second surface texture, wherein an outer surface of the insulative layer emulates the first surface texture in the first region of the insulative layer and emulates the second surface texture in the second region of the insulative layer.