Split-Piston Metering Pump Using Radial Seals for Precise Dosing
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Solution Overview
Problem
Existing micropumps for subcutaneous drug delivery are complex and costly, and they often require a rigid reservoir, limiting their compactness and dosing precision, especially when trying to deliver precise amounts of medication like insulin.
Innovation Solution
A micropump design featuring a flexible reservoir, a motor, gear, drive rack, and tubular pump housing with axially oriented drive and floating pistons, which create a pump volume space through frictional engagement of radial seals, allowing for precise fluid delivery without direct motor calibration, enabling a compact and cost-effective solution for medication infusion.
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 flexible reservoir cannot be used
Solution Approach 1:
The patent replaces the traditional lead screw mechanical system with a rotary vane pump mechanism. The motor rotates the rotor with vanes that create variable volume chambers, eliminating the need for lead screw, nut, and rigid reservoir calibration. Dosing precision is achieved through controlled rotational movement and chamber volume variation rather than linear screw advancement.
Solution Approach 2:
The patent introduces a flexible reservoir that can deform to accommodate the pumping action. The flexible membrane allows the reservoir to expand and contract as medication is delivered, replacing the rigid reservoir requirement. This flexibility enables the system to work with simpler pumping mechanisms while maintaining dosing accuracy.
2Measurement 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 uses a rotor with curved vanes that rotate within a stator, creating smooth variable volume chambers. The curved geometry of the vanes and chambers replaces the complex angled sealing rings, achieving precise liquid movement through rotational volume change rather than linear sealing ring movement. This curved design simplifies the overall pump structure.
Solution Approach 2:
The patent employs periodic rotation of the rotor to create repeating cycles of chamber expansion and compression. Each rotation cycle delivers a precise volume of liquid through the sequential opening and closing of inlet and outlet ports. This periodic rotational action replaces the continuous linear movement of angled sealing rings, simplifying the mechanism while maintaining precision.
3Measurement precision
If motor precision is used for dosing control, then dosing accuracy can be achieved, but the cost increases and calibration becomes difficult
Solution Approach 1:
The patent replaces motor-driven lead screw calibration with a rotor-stator pump mechanism where dosing volume is determined by the geometric dimensions of the vanes and chambers. The motor simply provides rotational motion, while the pump geometry defines the delivered volume, eliminating the need for precise motor positioning and calibration.
Solution Approach 2:
The patent changes the control parameter from motor position/calculation to rotor rotation angle and chamber volume. By making the dosing volume a function of the rotor's geometric parameters rather than motor control precision, the system achieves dosing accuracy through mechanical design rather than electronic calibration, simplifying manufacturing.
4Device complexity
If a compact micropump design with flexible reservoir is created, then cost effectiveness and user convenience improve, but achieving precise dosing becomes more difficult
Solution Approach 1:
The patent places the rotor with vanes inside the stator housing, creating a nested configuration where the rotating vanes define pumping chambers within the stator cavity. The flexible reservoir is positioned to interface with this compact rotor-stator assembly, allowing precise dosing within a small footprint. This nested arrangement achieves both compactness and dosing precision simultaneously.
Solution Approach 2:
The patent transitions from linear pumping motion to rotational motion, utilizing the third dimension of rotation to create variable volume chambers. The rotor vanes move in a circular path, creating expanding and compressing chambers that deliver precise doses. This rotational dimension allows compact design while maintaining dosing accuracy through controlled volume change.
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 micropump achieves precise and efficient delivery of medication, with a compact design and flexible reservoir, allowing for precise dosing and a smaller footprint, enhancing user convenience and reducing operational costs.
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
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.