Capillary Flow Restrictor with Sedimentation Chamber
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Solution Overview
Problem
Current infusion systems, particularly ambulatory pumps, face challenges in maintaining a uniform flow rate and are prone to clogging due to the use of capillary tubes with small diameters, which are difficult to manufacture accurately and are susceptible to contamination and particulate issues, leading to non-uniform and unreliable medication delivery.
Innovation Solution
A fluid flow restrictor design featuring a capillary tube surrounded by a sleeve with a chamber that slows the fluid velocity, allowing contaminants to settle out before reaching the capillary tube, thereby reducing clogging and ensuring a consistent flow rate, while being cost-effective and adaptable for different sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a capillary tube with small diameter is used to restrict flow rate, then the flow rate can be controlled to achieve desired therapeutic effect, but the capillary tube is prone to clogging by contaminants and particulates
Solution Approach 1:
The flow restrictor is divided into multiple functional segments: a larger diameter first capillary section for initial flow restriction and contaminant trapping, and a smaller diameter second capillary section for precise flow rate control. This segmentation allows each section to perform its specific function optimally without compromising the other.
Solution Approach 2:
The first capillary section with larger diameter acts as a preliminary filter that traps contaminants and particulates before the fluid reaches the second capillary section. This preliminary action prevents clogging of the more critical smaller diameter section while maintaining accurate flow rate control.
2Measurement precision
If capillary tubes with small diameters are used for flow restriction, then accurate flow rate control is achieved, but manufacturing precision becomes difficult and costly
Solution Approach 1:
The capillary tube is segmented into two sections with different diameters. The first section has a larger diameter that is easier to manufacture with consistent precision, while the second section has a smaller diameter for accurate flow control. This segmentation reduces the overall manufacturing difficulty while maintaining flow rate accuracy.
Solution Approach 2:
Different sections of the capillary tube have different diameters optimized for their specific functions. The first section has larger diameter for manufacturing ease and contaminant trapping, while the second section has smaller diameter for precise flow control. This local quality variation optimizes both manufacturing and performance.
3Ease of manufacture
If flow restrictors are made at low cost for disposable ambulatory pumps, then device affordability is improved, but flow rate uniformity and accuracy deteriorate
Solution Approach 1:
The flow restrictor uses a segmented capillary design that can be manufactured using standard techniques at reasonable cost. The two-section structure provides accurate flow control without requiring expensive specialized manufacturing processes, making it suitable for disposable ambulatory pumps.
Solution Approach 2:
The flow restrictor parameters (diameters, lengths of capillary sections) are optimized to achieve uniform flow rate control. By carefully selecting these parameters, accurate flow regulation is achieved while maintaining manufacturing feasibility and cost-effectiveness for disposable devices.
4Measurement precision
If gravity infusion systems are used to maintain uniform flow rate, then flow uniformity is improved, but the system becomes impractical for ambulatory patients requiring portability
Solution Approach 1:
The patent replaces the gravity-based mechanical system with a capillary flow restrictor that uses surface tension and viscous forces to control flow rate. This substitution enables portable ambulatory pump design while maintaining flow uniformity through the capillary effect, which is independent of gravitational orientation.
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 filters contaminants, maintains a consistent flow rate, and reduces the likelihood of clogging, providing a reliable and cost-effective means for ambulatory infusion systems to deliver medications uniformly and efficiently.
Implementation Method 1
a capillary tube to restrict the flow to a desired rate
Implementation Method 2
The capillary tube is surrounded by a sleeve over less than the entire length of the capillary tube, wherein the sleeve mounts the capillary tube such that the proximal end of the capillary tube projects into the chamber
Data Source
AI summary
A fluid flow rate control system and method comprises a capillary tube having a proximal end that projects into a chamber with a cross-sectional area that is larger than or equal to the fluid supply tube's cross-sectional area. The inner cross-sectional area of the capillary tube is configured less than the inner cross-sectional area of the chamber. The chamber has a volume large enough to slow the fluid conducted to it by the upstream fluid line to permit contaminants to fall out of solution. In another aspect, a sleeve is used to mount the capillary tube into the chamber. The sleeve provides a mounting surface for tube segments from the pump and downstream of the capillary restrictor.