Elastomeric Infusion Bladder with Tapered Wall Thickness
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Solution Overview
Problem
Conventional infusion assemblies for ambulatory intravenous delivery of pharmaceutically active liquids face challenges such as high variability in pressure and flow rate, difficulty in dispensing all liquid by the end of the infusion period, and residual liquid in the bladder.
Innovation Solution
The design of an elastomeric bladder with a body extending from a first end to a second end, featuring a varying wall thickness that tapers from each end toward a midpoint, and a mandrel with a varying outer diameter to reduce crack and fill pressures and enhance consistent infusion pressure and flow rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the bladder wall thickness is uniform, then the manufacturing process is simple, but the infusion pressure and flow rate vary widely
Solution Approach 1:
The bladder wall thickness is varied locally along its length, being thinner at the ends and thicker at the midpoint. This non-uniform thickness distribution creates more consistent infusion pressure and flow rate by compensating for pressure variations that occur during liquid dispensing, while still maintaining a relatively simple manufacturing process through extrusion or molding techniques.
2Stress or pressure
If the mandrel outer diameter is reduced, then the crack and fill pressure decrease, but the structural strength may be compromised
Solution Approach 1:
The mandrel outer diameter is reduced in specific regions (at the ends) while maintaining adequate strength through the non-uniform geometry. This localized dimension optimization reduces the crack and fill pressures required for operation while the overall mandrel structure maintains sufficient structural integrity through its design configuration.
3Device complexity
If conventional bladders are used, then the device structure is simple, but residual liquid remains in the bladder at the end of infusion
Solution Approach 1:
The bladder wall thickness is optimized locally, being thinner at the ends where liquid dispensing occurs. This design allows the bladder to collapse more completely during infusion, enabling substantially all liquid to be dispensed by the end of the infusion period while minimizing residual liquid volume, all while maintaining a simple overall bladder structure.
Data Source
AI summary
Bladders and elastomeric pumps for infusion assemblies are provided. For example, a bladder may comprise a body extending over a length from a first end to an opposing second end; an outer diameter; an inner diameter; and a wall thickness. The wall thickness may gradually transition from a first wall thickness at the first end to a second wall thickness at the second end. In other embodiments, the wall thickness at a midpoint of the length is different than the wall thickness at each of the first end and the second end. An elastomeric pump may comprise an inflatable elastomeric bladder and a mandrel. The bladder includes a body extending over a bladder length from a first bladder end to an opposing second bladder end and a wall thickness, which is different at a midpoint of the bladder length than at each of the first and second bladder end.