Segmented Cytology Brush with Variable Stiffness for Biliary Tract Sampling
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Solution Overview
Problem
Existing cytology brushes face challenges in accessing difficult-to-reach anatomy and effectively collecting and retaining tissue samples, particularly in the gastrointestinal tract and biliary tract, due to issues with bristle stiffness, frictional forces, and sample collection efficiency.
Innovation Solution
The improved cytology brush features a design with multiple brush portions of varying stiffness, including stiff proximal and distal portions for tissue abrasion and a softer central portion for sample collection, along with gaps between the portions to enhance tissue collection and retention, reducing frictional forces during extension and retraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a cytology brush uses stiff bristles throughout to effectively abrade and collect tissue samples, then tissue sample collection efficiency is improved, but frictional forces during extension and retraction increase, making deployment difficult
Solution Approach 1:
The brush is divided into multiple distinct sections along its length, with each section having different bristle stiffness characteristics. The distal section (at the tip) has stiffer bristles for effective tissue abrasion, while proximal sections have progressively softer bristles. This segmentation allows the brush to maintain high tissue collection efficiency at the working end while reducing overall friction during deployment and retraction through the flexible shaft.
Solution Approach 2:
Different portions of the brush are given locally optimized properties: the distal portion has stiff bristles specifically where tissue contact occurs to maximize sample collection, while the proximal portions have softer bristles that reduce friction against the shaft wall during extension and retraction. This local differentiation of bristle stiffness resolves the contradiction between effective tissue abrasion and ease of deployment.
2Ease of manufacture
If a cytology brush uses uniform bristle stiffness to simplify manufacturing, then manufacturing complexity is reduced, but tissue sample retention and collection efficiency deteriorate due to inability to optimize different brush portions
Solution Approach 1:
The brush manufacturing process is segmented into multiple steps where different bristle stiffnesses are applied to different sections. This is achieved by dividing the shaft into discrete zones and selectively applying bristles with appropriate stiffness characteristics to each zone, thereby optimizing both tissue collection and retention while maintaining a systematic manufacturing approach.
Solution Approach 2:
The manufacturing process incorporates local quality differentiation by applying bristles with varying stiffness properties to specific locations along the shaft. The distal region receives stiffer bristles for effective tissue abrasion, while proximal regions receive softer bristles for reduced friction and improved sample retention during retraction.
3Productivity
If a cytology brush uses long bristles to increase tissue contact area, then tissue sample collection capacity is improved, but frictional forces during retraction increase, causing brush buckling and sample loss
Solution Approach 1:
The bristle length and stiffness are locally optimized: distal bristles are longer and stiffer to maximize tissue contact area and collection capacity at the working end, while proximal bristles are shorter and softer to minimize friction during retraction and prevent buckling. This local differentiation resolves the contradiction between collection capacity and retraction friction.
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 design allows for efficient tissue sample collection and retention, reducing the force required for brush deployment and retraction, and maximizing the quantity of cells collected, especially in hard-to-reach areas like the biliary tract.
Implementation Method 1
reducing frictional forces during extension and retraction
Implementation Method 2
stiff proximal and distal portions for tissue abrasion
Data Source
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AI summary
A tissue collection apparatus maximizes the collection and retention of tissue samples from within a patient. The apparatus comprises a handle with a hollow catheter flexibly extending distally from the handle. A cytology brush is stored within the hollow at a distal end of the cannula, and can be extended and retracted from the cannula by manipulating the handle. The cytology brush has a cylindrical proximal brush, a cylindrical distal brush, and a tissue collection gap longitudinally separating the proximal and distal brushes. The bristles of the brushes can have different material properties and can have an effective diameter greater than the cannula. In use, tissue samples accumulate within the bristles and within the tissue collection gap. When retracted into the hollow of the cannula, the apparatus maximizes the amount of tissue collected by folding the bristles over the tissue collection gap to shield the tissue samples collected within.