Osmotic Piston Assembly Sealing Against Organic Solvent Leaching
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Solution Overview
Problem
Existing osmotic delivery systems face challenges in maintaining compatibility and sealing of pistons with components, particularly when exposed to organic solvents, leading to leaching issues that affect the integrity and performance of the system.
Innovation Solution
The development of a piston assembly with a body made from polymeric materials resistant to leaching in organic solvents, featuring a columnar design with a rim and spring mechanism for sealing, and the use of elastomeric O-rings to ensure a reliable seal within the osmotic delivery system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional elastomeric materials are used for the piston, then the piston can deform to fit the lumen and provide sealing, but the piston becomes incompatible with organic solvents and exhibits leaching
Solution Approach 1:
The piston is constructed from a composite material system consisting of a polymeric body (such as polyolefin, polyethylene, or polypropylene) combined with elastomeric sealing components (O-rings, gaskets, or lips). This composite approach allows the main body to resist organic solvent leaching while the elastomeric sealing elements provide the necessary deformation and sealing capability against the reservoir wall.
Solution Approach 2:
Different portions of the piston are made from materials with different properties: the main body uses solvent-resistant polymeric material for structural integrity and chemical compatibility, while localized sealing portions use elastomeric materials that can deform to create tight seals. This local differentiation of material properties resolves the contradiction between chemical resistance and sealing capability.
2Reliability
If the piston material is made softer to improve sealing against the reservoir wall, then sealing improves, but the piston becomes more susceptible to degradation in organic solvents
Solution Approach 1:
The piston combines soft elastomeric sealing elements with a harder, chemically resistant polymeric body. The elastomeric portions (O-rings, lips, or gaskets) provide the softness needed for sealing against the reservoir wall, while the polymeric body maintains dimensional stability and resistance to organic solvent degradation.
Solution Approach 2:
The piston structure differentiates between sealing surfaces and structural portions, using softer elastomeric materials only where contact with the reservoir wall is required for sealing, while the bulk of the piston uses harder, more chemically stable polymeric material that resists solvent degradation.
3Strength
If a rigid material is used for the piston body to maintain structural integrity, then strength improves, but the piston cannot deform to fit the lumen for proper sealing
Solution Approach 1:
The piston uses a composite construction where a rigid or semi-rigid polymeric body provides structural integrity and strength, while flexible elastomeric sealing components (such as O-rings, lips, or gaskets) are integrated to provide the deformation capability needed for sealing against the reservoir wall.
Solution Approach 2:
The piston structure assigns different mechanical properties to different regions: the main body uses rigid polymeric material for strength and structural support, while localized sealing portions use flexible elastomeric material that can deform to conform to the reservoir wall and create effective seals.
4Reliability
If elastomeric materials are used for the piston, then sealing against the wall is improved, but leaching occurs when exposed to organic solvents
Solution Approach 1:
The piston combines elastomeric sealing elements with polymeric body material. The elastomeric components (O-rings, gaskets, lips) provide effective sealing against the reservoir wall, while the polymeric body material (such as polyolefin, polyethylene, or polypropylene) resists leaching when exposed to organic solvents, preventing contamination of the active agent formulation.
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 provides a reliable, long-lasting seal and prevents leaching, ensuring the integrity and effectiveness of the osmotic delivery system, even when exposed to organic solvents, thereby maintaining consistent and controlled release of active agents.
Implementation Method 1
a spring (e.g., a radial spring, such as a canted coil spring) retained in a cavity for biasing the rim against the wall of the reservoir
Implementation Method 2
The body is typically made of material that is resistant to leaching in an organic solvent, for example, a polymeric material
Implementation Method 3
The first chamber contains an osmotic agent formulation while the second chamber contains an active agent formulation. Pressure differential across the piston allows the piston to move longitudinally within the reservoir
Data Source
AI summary
An osmotic delivery system is disclosed for delivering an active agent formulation to a fluid environment. The osmotic delivery system typically comprises a reservoir having a lumen that contains the active agent formulation and an osmotic agent formulation and a piston assembly positioned in the lumen to isolate the active agent formulation from the osmotic agent formulation. The piston assembly typically comprises a body constructed and arranged for positioning in the lumen. The body is typically made of a polymeric material that is, for example, resistant to leaching in an organic solvent. In one embodiment, the body is a columnar body having a rim at a distal end thereof for engaging and sealing against a wall of the reservoir and the piston assembly further comprises a spring retained at the distal end of the columnar body for biasing the rim of the columnar body against the wall of the reservoir.