Thin-Wall Cannula Hydrodynamic Geometry for Low-Force Injection
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Solution Overview
Problem
Cannulas for syringes face a challenge in minimizing outer diameter to reduce patient discomfort while maintaining sufficient inner diameter for fluid flow, regardless of drug viscosity.
Innovation Solution
A medical injection cannula with a specific length-to-diameter ratio (L hydrodynamic theoretical needle / D needle_inner 4) between 7.00×10 11< and 9.40×10 12< m -3< , optimized for 27G, 29G, or 30G standards, and a flow factor K 1 approximated by 8 * π * (D barrel 4 / L hydrodynamic * D needle_inner 4) to balance outer diameter and inner diameter for efficient fluid flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the outer diameter of the cannula is minimized to reduce patient discomfort, then the inner diameter becomes insufficient for adequate fluid flow
Solution Approach 1:
The patent applies parameter changes by optimizing the length-to-diameter ratio (L/D4) to a specific range (7.00×10^11 to 9.40×10^12 m^-3) and controlling the flow factor K1 within defined ranges. This allows the cannula to achieve both minimal outer diameter for patient comfort and sufficient inner diameter for adequate fluid flow rate, resolving the contradiction between these two parameters.
2Productivity
If the inner diameter of the cannula is increased to allow adequate fluid flow, then the outer diameter increases causing patient discomfort
Solution Approach 1:
The patent resolves this contradiction by establishing specific parameter ranges for the length-to-diameter ratio (L/D4 between 7.00×10^11 and 9.40×10^12 m^-3) and flow factor (K1 between 7,000 and 31.548×10^6). These parameter changes enable the cannula to maintain sufficient inner diameter for fluid flow while keeping the outer diameter minimal for patient comfort.
3Strength
If the cannula length is increased to maintain structural integrity, then the fluid flow resistance increases
Solution Approach 1:
The patent addresses this contradiction by optimizing the length-to-diameter ratio parameter (L/D4) within the range of 7.00×10^11 to 9.40×10^12 m^-3. This parameter optimization allows the cannula to achieve the necessary structural integrity for safe use while maintaining sufficient fluid flow rate by preventing excessive length relative to the inner diameter.
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 allows for reduced injection force and faster fluid injection while maintaining patient comfort by optimizing the cannula's dimensions for efficient fluid flow and reduced discomfort.
Implementation Method 1
a theoretical hydrodynamic length of the cannula L hydrodynamic theoretical needle, and wherein the length-to-diameter ratio is comprised between 7.00×10 11 and 9.40×10 12 m -3
Data Source
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AI summary
A medical injection cannula configured for use with a syringe includes a sidewall defining a lumen and having a proximal end and a distal end, and a beveled tip defining an opening to the lumen. A length-to-diameter ratio of the cannula is defined by a ratio LhydrodynamictheoreticalneedleDneedle_inner4, wherein Lhydrodynamic theoretical needle is a theoretical hydrodynamic length of the cannula, and Dneedle_inner is an inner diameter of the sidewall of the cannula. The length-to-diameter ratio is between 7.00×1011 and 9.40×1012 m-3.