Inline Mixer for Biological Fluid Collection
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Solution Overview
Problem
Conventional blood sampling techniques face challenges in achieving uniform anticoagulant distribution within biological fluids, leading to issues like hemolysis and clotting due to high or low anticoagulant concentrations, especially in point-of-care devices where initial blood samples pick up most of the anticoagulant, resulting in uneven concentrations throughout the sample.
Innovation Solution
A biological fluid collection device with an inline mixer that captures a high concentration front of anticoagulant within a centered mixing chamber and slowly releases it throughout the sample via a small exit aperture, ensuring head-to-tail uniformity through a two-stage mixing process, utilizing capillary assisted flow and a sample stabilizer like dry anticoagulant powder within the device's structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If anticoagulant is included as part of the manufactured device, then sample stabilization is achieved, but the first blood flowing into the device picks up a majority of the anticoagulant resulting in very high anticoagulant concentration in this first volume
Solution Approach 1:
The device pre-dissolves the anticoagulant in a reservoir before blood entry, creating a controlled source. The mixing chamber is pre-configured with the anticoagulant solution, and the system is designed to mix blood and anticoagulant in a controlled manner as blood flows through, preventing the initial high concentration problem by establishing proper mixing conditions before the first blood volume enters the collection area.
Solution Approach 2:
A hydrophilic coating is applied to the inner surfaces of the mixing chamber and flow path to act as an intermediary that promotes uniform anticoagulant distribution. This coating ensures that the anticoagulant is evenly distributed across the blood flow interface, preventing localized high concentration zones and ensuring consistent mixing throughout the sample volume.
2Reliability
If anticoagulant concentration is too high in the first volume of blood, then sample stabilization is achieved in that volume, but hemolysis is induced
Solution Approach 1:
The device controls the anticoagulant-to-blood ratio by designing the mixing chamber dimensions, flow path geometry, and anticoagulant reservoir size to achieve optimal mixing parameters. The system ensures that the anticoagulant concentration in each blood volume remains within the safe range by controlling the dissolution rate and distribution mechanism, preventing both under-dosing and over-dosing conditions that could cause hemolysis or clotting.
Solution Approach 2:
The hydrophilic coating serves as a mediator that controls the release and distribution of anticoagulant along the blood flow path. This coating ensures gradual and uniform anticoagulant transfer to the blood, preventing sudden high concentration spikes that would cause hemolysis while maintaining sufficient stabilization throughout the sample.
3Ease of operation
If anticoagulant concentration is too low in later volumes of blood, then device function is maintained, but clotting occurs which may plug microfluidic devices
Solution Approach 1:
The device design ensures continuous anticoagulant availability throughout the entire blood sampling process. The anticoagulant reservoir and dissolution mechanism are configured to maintain a steady supply of anticoagulant throughout the blood flow, ensuring that even the last volumes of blood receive adequate stabilization. The mixing chamber geometry and flow path are designed to maintain turbulent or enhanced mixing conditions throughout, preventing stagnant zones where clotting could occur.
4Reliability
If manual mixing with anticoagulant is performed, then sample stabilization is achieved, but the process is device intensive and increases time and cost
Solution Approach 1:
The device merges the anticoagulant reservoir, mixing chamber, and sample collection area into a single integrated cartridge. The anticoagulant is pre-loaded in the device, and the mixing process occurs automatically within the integrated structure as blood flows through the designated path. This eliminates the need for separate mixing devices, manual addition of anticoagulant, and multiple handling steps, reducing both device complexity and operational time while maintaining reliable sample stabilization.
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 ensures consistent anticoagulant distribution across the entire sample, preventing clotting and hemolysis, and maintains sample stability for accurate testing, particularly in small volumes where traditional mixing techniques are ineffective.
Implementation Method 1
utilizing capillary assisted flow
Implementation Method 2
The inner surface of the mixing chamber is treated with a hydrophilic coating to promote uniform mixing
Implementation Method 3
the captured front volume is then slowly released throughout a small exit hole and recombined with the rest of the flow volume
Data Source
AI summary
A biological fluid collection device (10) that produces a stabilized biological sample with head-to-tail uniformity through the capturing of a high concentration front and subsequent redistribution of the high concentration front throughout a biological fluid is disclosed. The biological fluid collection device includes an inline mixer (16) used for head-to-tail mixing of a concentrated flow front. The mixing is achieved via a two-stage process. First, a front fraction of the flow is captured within a centered mixing chamber (30) via capillary assisted flow action. Second, the captured front volume is then slowly released throughout a small exit hole (36) and recombined with the rest of the flow volume that was diverted around the centered mixer chamber.