Reagent Cartridge Pressure Control via Flow Resistance
Solution Overview
Problem
In microfluidic systems, the flow rates of fluids from flexible containers are not accurately controllable at the microliter per minute or hour level due to high and variable flow rates, often leading to contamination from gas dissolution or reaction with fluid constituents, and existing solutions do not adequately address precision and contamination issues.
Innovation Solution
A method using a rigid housing with a single pressure source to actuate multiple flexible reagent containers, where the ratio of resistances in connection ports and channels dictates flow rates, and the use of fluid impermeable containers to prevent contamination, along with a system for precise control of flow rates and simultaneous actuation of reagents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single pressure source is used to actuate multiple flexible reagent containers, then simultaneous delivery of multiple reagents is achieved, but flow rate control precision deteriorates due to high and variable flow rates
Solution Approach 1:
The patent applies local quality by providing individual flow control mechanisms (such as flow restrictors, capillaries, or valves) at each reagent container outlet. This allows each reagent stream to have its flow rate independently controlled and optimized, while still being actuated by a single pressure source. The local flow control elements create specific resistance characteristics that enable precise flow rate control despite the high pressure environment.
Solution Approach 2:
The patent utilizes parameter changes by varying the resistance characteristics of flow control elements (such as changing capillary dimensions, adjusting valve openings, or modifying flow restrictor geometry) to achieve desired flow rates. By carefully selecting and adjusting these resistance parameters, the system can deliver precise microliter-per-minute flow rates even when actuated by a single pressure source that generates higher pressures.
2Ease of operation
If gases are used to pressurize fluids directly in rigid containers, then fluid delivery is simplified, but contamination occurs through gas dissolution or reaction with fluid constituents
Solution Approach 1:
The patent introduces an intermediary fluid (such as a liquid or inert gas) that transmits pressure from the pressure source to the reagent containers without directly contacting the reagents. This intermediary acts as a mediator that prevents direct contamination while still enabling effective pressure transmission. The intermediary fluid is selected to be chemically incompatible with the reagents, thereby preventing dissolution or reaction-based contamination.
Solution Approach 2:
The patent employs an inert atmosphere by using an inert gas (such as nitrogen or argon) or a chemically inert liquid as the pressure transmission medium. This inert environment prevents any chemical reactions or dissolution interactions between the pressurizing gas and the reagent constituents, thereby eliminating contamination while maintaining simple pressure-driven fluid delivery.
3Adaptability or versatility
If flexible containers are used to host fluids under pressure, then container flexibility is achieved, but flow rate control accuracy deteriorates due to high flow rates in the order of μL-10 mL/s
Solution Approach 1:
The patent applies local quality by incorporating specific flow control elements (such as capillaries, flow restrictors, or precision valves) at the outlet of each flexible container. These local control mechanisms create controlled resistance that compensates for the high flow rates inherent in flexible container systems, enabling precise microliter-per-minute flow rate control while maintaining the advantages of flexible pressure-adaptable containers.
Solution Approach 2:
The patent utilizes pneumatic and hydraulic principles by carefully designing the flow control elements to create specific pressure drops and flow resistance characteristics. By applying fluid dynamics principles, the system can translate the high pressure capability of flexible containers into precise low flow rates through properly designed restrictors and capillaries with specific dimensional parameters.
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 approach allows for precise control of flow rates, minimizes contamination by preventing gas ingress, and ensures consistent delivery of reagents to microfluidic devices, enhancing the accuracy and reliability of fluid delivery in microfluidic systems.
Implementation Method 1
a single pressure source (18) configured to apply pressure to the interior of the rigid housing... the plurality of channels (20) configured to transfer fluid from the plurality of reagent containers to the microfluidic device
Implementation Method 2
the ratio of resistances provided by a combination of the connection ports and the plurality of channels dictates the ratio of flow rates of the reagents
Implementation Method 3
the use of fluid impermeable containers to prevent contamination
Data Source
Figure 1
Figure 2
AI summary
A fluidic system is provided. The system comprises: a rigid housing (12), a plurality of flexible reagent containers (14) contained within the housing (12); wherein each reagent container (14) has a connection port (16) through which a reagent can flow, in use, on the application of pressure. The system further comprises a single pressure source (18) configured to apply pressure to the interior of the rigid housing (12); a microfluidic device configured to analyse one or more fluids provided from the plurality of reagent containers; and a plurality of channels (20) configured to transfer fluid from the plurality of reagent containers (14) to the microfluidic device. The ratio of resistances provided by a combination of the connection ports and the plurality of channels dictates the ratio of flow rates of the reagents. The claimed system allows for an accurate control of the various reagent flow rates while minimizing fluctuations in the relative flow rates.