Ribbed Drug Delivery Plunger for Low-Friction Viscous Injection
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Solution Overview
Problem
Conventional plungers for drug delivery devices experience high friction and variability when handling high viscous products, leading to increased driving forces and unpredictability in drug delivery times, due to radial deformation and increased contact area with the syringe or reservoir.
Innovation Solution
The design of a plunger with radially outward ribs that maintain a consistent contact area and high contact pressure, minimizing radial expansion under axial loads, which reduces friction and variability, and includes features like a roughened leading surface and protrusions to enhance sealing and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional cylindrical plunger is used, then the plunger can seal with the syringe or reservoir, but large axial compressive forces cause radial deformation and increased contact area, resulting in greater friction and unpredictability
Solution Approach 1:
The plunger body is segmented into multiple ribs spaced axially apart by recessed side surfaces. This segmentation reduces the contact area between the plunger and syringe/reservoir while maintaining sealing effectiveness, thereby reducing friction and improving predictability during extrusion of high viscous products
Solution Approach 2:
The ribs are designed with specific geometries including curved profiles and cylindrical portions to optimize local contact characteristics. This allows the plunger to maintain high contact pressure where needed for sealing while minimizing overall contact area to reduce friction
2Productivity
If large driving forces are applied to deliver high viscous products within required time, then drug delivery time requirement is met, but the plunger experiences increased radial deformation and friction
Solution Approach 1:
The ribbed structure segments the plunger body to reduce contact area with the syringe or reservoir. This reduction in contact area directly reduces friction during extrusion, making the extrusion process more predictable and reliable when large driving forces are applied to deliver high viscous products within required timeframes
Solution Approach 2:
The plunger geometry is changed from a solid cylinder to a ribbed structure, fundamentally altering the contact parameters between plunger and syringe/reservoir. This geometric parameter change reduces the contact area while maintaining sealing effectiveness, thereby reducing friction and improving predictability under high loading conditions
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 configuration results in a 30% reduction in injection time and lower friction variability compared to conventional plungers, enabling more robust and efficient high viscosity drug delivery devices.
Implementation Method 1
The body portion is configured to occupy a first configuration in the absence of an axial load, and a second configuration in the presence of an axial load, where the first and second configurations have a substantially equal radial dimension and the second configuration has an axial dimension that is less than an axial dimension of the first configuration
Data Source
AI summary
A plunger configured as described herein provides geometry optimizations to minimize friction magnitude and variability during use by maintaining low deformation under large extrusion forces. More specifically, plunger embodiments described herein minimize a contact area between the plunger and a syringe or chamber, while also maintaining high contract pressures to maintain container closure integrity. Moreover, the plunger embodiments are configured to have minimal or no increase in the contact area under high loads associated with the delivery of viscous products.