Microfluidic Valve With Magnetic Plunger for Sub-Microliter Dispensing
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Solution Overview
Problem
Current mechanical pipetting devices in the microfluidic field face limitations in accuracy and precision for dispensing fluids in the sub-microliter range, particularly in in-vitro diagnostics, where precise dosage and prevention of cross-contamination are crucial.
Innovation Solution
A microfluidic valve system comprising a dry and wet portion, where only the wet portion contacts the fluid, utilizing a capillary nozzle and plunger mechanism with a magnetic closing component to ensure precise dispensing and prevent cross-contamination, allowing for sub-microliter range dispensing without direct contact between the closing component and the fluid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a mechanical pipetting device is used for dispensing fluids, then the device structure is simple, but the accuracy and precision of dosage in the sub-microliter range deteriorates
Solution Approach 1:
The valve is divided into a disposable wet portion (capillary nozzle, cavity, plunger) and a reusable dry portion (closing component with magnet). This segmentation allows the critical fluid-contact components to be optimized for precision while keeping the overall device structure simple and cost-effective.
Solution Approach 2:
The mechanical closing force is replaced with a magnetic closing force exerted by the closing component on the plunger. This substitution enables more precise control of the plunger movement and valve closing action, improving dispensing accuracy in the sub-microliter range.
2Device complexity
If the closing component contacts the fluid directly, then the valve structure is simplified, but cross-contamination and carry-over effects worsen
Solution Approach 1:
The valve is segmented into a wet portion that contacts the fluid (capillary nozzle, cavity, plunger) and a dry portion that does not (closing component). The wet portion is designed as disposable to prevent cross-contamination, while the dry portion with the magnetic closing component remains reusable, eliminating carry-over effects.
Solution Approach 2:
The plunger acts as an intermediary between the closing component and the fluid. It transmits the magnetic closing force to seal the capillary nozzle without requiring the closing component to contact the fluid directly, thus preventing cross-contamination.
3Manufacturing precision
If the closing component is made of expensive materials, then the valve precision is improved, but the manufacturing cost increases
Solution Approach 1:
The valve components are segmented into disposable wet portion and reusable dry portion. The precision-critical plunger and capillary nozzle are made as disposable wet portion using low-cost materials, eliminating the need for expensive precision materials in the closing component while maintaining overall valve precision.
Solution Approach 2:
The wet portion containing the capillary nozzle, cavity, and plunger is designed as a disposable component made from low-cost materials. This allows high precision to be achieved in the fluid-contact components without requiring expensive materials in the reusable closing component, significantly reducing manufacturing costs.
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 system enables precise and accurate dispensing of fluids in the sub-microliter range, reduces the risk of cross-contamination, and lowers costs by using low-cost materials for the disposable wet portion, while the reusable dry portion prevents carry-over effects and thermal damage to sensitive fluids.
Implementation Method 1
The dry portion comprises a closing component for exercising a magnetic closing force onto the plunger for moving the plunger into the closing position. At least one of the closing component and the plunger comprises a permanent magnet for keeping the valve in its normally-closed state.
Implementation Method 2
a capillary nozzle providing a fluid outlet
Data Source
AI summary
A valve for dispensing a fluid comprising a dry portion and a wet portion is presented. Only the wet portion is contacted by the fluid. The wet portion comprises a fluid dispenser unit having a inlet opening, a capillary nozzle providing a fluid outlet, a cavity, the capillary nozzle having an end within the cavity, and a plunger. The plunger moves within the cavity into an opening position allowing an inflow of the fluid through the inlet opening through the cavity and an outflow of the fluid through the capillary nozzle. The plunger has a sealing surface directed towards the end of the capillary nozzle. The plunger moves into a closing position for sealing the end of the capillary nozzle with the sealing surface. The dry portion comprises a closing component for exercising a magnetic closing force onto the plunger for attracting the plunger into the closing position.