Microfluidic Blood Test Element with Capillary Dilution
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Solution Overview
Problem
Current blood analysis test elements require complex manual handling and expensive laboratory instruments for determining haemoglobin and glycohaemoglobin levels, which are error-prone and costly, especially when the analyte is present at high concentrations.
Innovation Solution
A microfluidic channel structure with a dilution channel and separation means for retaining corpuscular blood components, allowing for automatic dilution and separation of blood samples within the test element, enabling one-step determination of total haemoglobin and glycohaemoglobin values without additional reagents or complex mechanical interactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a blood sample is analyzed directly without dilution, then the analysis can be performed with minimal sample preparation, but the high concentration of haemoglobin and interfering components reduce measurement precision and require expensive laboratory instruments
Solution Approach 1:
The test element is divided into multiple functional zones including a first capillary-active zone for plasma separation and a second capillary-active zone for dilution. This segmentation allows complex analytical tasks to be distributed across specialized regions, improving measurement precision while keeping each zone's function simple and reliable
Solution Approach 2:
The patent introduces an intermediary dilution step using the second capillary-active zone that acts as a mediator between the high-concentration blood sample and the analytical measurement. This intermediary zone dilutes the sample with buffer solution, reducing haemoglobin concentration and interfering components to levels suitable for precise measurement without requiring complex laboratory instruments
2Measurement precision
If plasma separation is performed using a porous matrix material, then interfering components are removed, but the separation process becomes complex and requires additional reagents
Solution Approach 1:
The first capillary-active zone with porous matrix material performs plasma separation autonomously using capillary forces alone, without requiring additional reagents or external power sources. The zone self-regulates the separation process based on the blood sample's properties, removing interfering components while minimizing reagent consumption and maintaining measurement precision
Solution Approach 2:
The patent utilizes capillary action (a hydraulic principle) to drive the plasma separation process through the porous matrix material. The capillary forces naturally draw the blood sample through the separation zone and regulate flow rates, eliminating the need for pumps, valves, or additional reagents while achieving effective separation of plasma from cellular components
3Ease of operation
If manual handling steps are used for sample preparation, then the process is simple to manufacture, but the user interaction increases and error-prone steps are introduced
Solution Approach 1:
The patent replaces manual mechanical handling steps with an automated microfluidic system that uses capillary forces to transport and process the blood sample. The channel structure automatically guides the sample through separation and dilution zones without requiring user manipulation, eliminating error-prone manual steps while maintaining ease of operation through simple sample application
Solution Approach 2:
The patent changes the flow rate parameter dynamically through the channel structure design, with the first zone operating at lower flow rates for effective plasma separation and the second zone operating at higher flow rates for efficient dilution. This parameter optimization ensures reliable automated processing while keeping the system easy to operate through passive capillary-driven flow control
4Measurement precision
If additional reagents are added for dilution, then the sample concentration is reduced, but the reagent cost increases and handling complexity increases
Solution Approach 1:
The patent discards the need for expensive external reagents by using the second capillary-active zone to perform dilution with buffer solution that is already integrated into the test element structure. The zone recovers and utilizes the plasma separated in the first zone for dilution, eliminating waste and reducing reagent consumption while maintaining measurement precision through controlled dilution
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
Enables cost-effective, user-friendly blood tests with reduced reagent consumption by automating the sample preparation and analysis process, allowing for accurate determination of haemoglobin and glycohaemoglobin levels in a single-step procedure using a disposable test element.
Implementation Method 1
a channel or flow structure that is specially designed for separating plasma or serum from a whole blood sample and comprises two capillary-active zones
Implementation Method 2
a first zone is composed of a porous matrix material
Data Source
AI summary
An analytical test element for blood analyses is provided having at least a substrate body having a channel structure for the flow transport of a blood sample from an application site to at least one analytical site. The channel structure has a dilution channel that can be loaded with the blood sample and is provided with a separation component for retaining corpuscular blood components and has a sample channel which conveys a blood sample aliquot to be diluted and joins the dilution channel at a mixing site.