Split Piston Micropump With Friction Seals for Precise Dosing
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Solution Overview
Problem
Existing micropumps for subcutaneous drug delivery are complex and costly, and require rigid reservoirs for precise dosing, limiting their compactness and flexibility, while also being dependent on motor precision for medication delivery.
Innovation Solution
A micropump design featuring a flexible reservoir, a cannula, motor, gear, drive rack, and tubular pump housing with axially oriented drive and floating pistons, where the relative position of the pistons defines a pump volume space, allowing for precise fluid delivery through frictional engagement of radial seals, enabling compact and cost-effective operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a rigid reservoir with lead screw is used for medication delivery, then dosing precision can be achieved, but the device complexity increases and flexibility is limited
Solution Approach 1:
The patent replaces the traditional lead screw mechanical system with a friction-based piston system. The drive piston translates axially within the pump housing, and friction between the piston and housing walls controls fluid displacement. This substitution eliminates the complex lead screw mechanism while achieving precise dosing through controlled friction engagement, directly resolving the contradiction between dosing precision and device complexity.
Solution Approach 2:
The patent changes the fundamental operating parameter from rigid mechanical engagement (lead screw threads) to friction-based engagement (piston-wall contact). This parameter change allows the system to achieve precise medication delivery through controlled friction forces rather than rigid mechanical constraints, reducing device complexity while maintaining dosing accuracy.
2Measurement precision
If a rigid reservoir is used for calibrated dosing, then dosing accuracy is maintained, but the number of possible layouts is limited and compactness is reduced
Solution Approach 1:
The patent employs a flexible reservoir instead of a rigid one, allowing the medication storage container to be compact and adaptable to various layouts. The flexible nature of the reservoir enables it to collapse as medication is delivered, maximizing space efficiency while maintaining dosing accuracy through the friction-controlled piston mechanism. This directly addresses the contradiction by enabling compact design without sacrificing dosing precision.
3Measurement precision
If motor precision is increased for better medication delivery, then dosing precision improves, but device complexity and cost increase
Solution Approach 1:
The patent substitutes the motor-driven lead screw system with a friction-based piston translation system. Instead of relying on high-precision motors and threaded mechanisms, the system uses controlled friction between the drive piston and pump housing walls to achieve precise medication delivery. This substitution reduces dependence on motor precision while lowering device complexity and cost.
Solution Approach 2:
The friction between the piston and housing walls provides self-regulating control of fluid delivery. The friction force automatically adjusts to maintain controlled piston movement and precise dosing without requiring high-precision motors or complex control systems. This self-service mechanism achieves dosing precision through passive friction control rather than active motor precision.
4Measurement precision
If sealing rings at angle on axial extensions are used, then liquid movement precision is achieved, but the pump design becomes complex and not cost effective
Solution Approach 1:
The patent replaces the complex angled sealing ring system with a simpler friction-based sealing approach. Instead of requiring precisely positioned angled sealing rings on axial extensions, the system uses friction between the piston surface and housing wall to control fluid movement and maintain sealing. This substitution significantly simplifies manufacturing while maintaining liquid movement precision.
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 design achieves precise and efficient delivery of medication with a compact footprint, independent of motor precision, using a flexible reservoir and frictional engagement of seals to control fluid flow, enhancing dosing accuracy and reducing complexity and cost.
Implementation Method 1
the frictional engagement of radial seals on the drive piston and/or the floating piston with the interior surface of the tubular pump housing determines the opening and closing of the apertures in the pump housing
Data Source
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AI summary
A micropump according to the invention uses axially oriented pistons to define a pump volume. Translating the pistons axially with respect to each other within a pump housing draws a metered amount of fluid into the pump volume from a reservoir port for delivery to a cannula port when the space is collapsed. Radially situated seals on the pistons cooperate with the axial movement to close off and open the cannula port and the reservoir port respectively at different positions of the piston stroke.