Capillary Blood Characterization Using Gas-Liquid Interface
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Solution Overview
Problem
Existing methods for characterizing blood samples, such as those described in document WO 2009/053841, face challenges in reproducibility and discrimination of different blood samples, particularly in mimicking physiopathological conditions effectively.
Innovation Solution
The method involves creating a controlled shear rate environment within a capillary channel, with initial high shear rates exceeding 10,000 s^-1 that decrease to less than 1000 s^-1, using a constant pressure difference and air as the gas, allowing for the measurement of electrical signals while the blood sample flows through electrodes located in a serpentine channel, without the addition of activators, to mimic physiological and pathological conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a capillary is pre-filled with water and then a blood sample is introduced, then the passage of the front separating the two liquids produces a measurable change in capacitance, but the reproducibility of measurements is poor and discrimination of different blood samples is limited
Solution Approach 1:
The patent changes the physical parameters of the system by replacing the water-blood interface method with a gas-liquid interface method. This fundamental parameter change in the measurement approach enables both improved reproducibility and better discrimination of different blood samples by creating more controlled and consistent flow conditions through the capillary channel.
Solution Approach 2:
The patent applies pneumatic principles by introducing a gas phase into the capillary channel to create a gas-liquid interface. This pneumatic approach allows for better control of fluid flow and measurement conditions, leading to improved measurement reproducibility and enhanced ability to discriminate between different blood samples compared to the purely liquid-based prior art method.
2Reliability
If the blood sample flows through the channel under constant pressure difference, then the shear rate decreases over time as the front advances, but maintaining physiological relevance while achieving stable measurements is challenging
Solution Approach 1:
The patent applies preliminary action by pre-establishing the constant pressure difference and gas-liquid interface configuration before the blood sample enters the measurement zone. This preliminary setup ensures that the blood sample experiences controlled, physiologically relevant shear conditions from the moment of introduction, improving both the reproduction of pathophysiological conditions and measurement stability.
Solution Approach 2:
The patent embraces the dynamic nature of shear rate changes during blood flow through the capillary. Rather than attempting to maintain constant shear rate, the system accepts and utilizes the natural decrease in shear rate over time as the front advances, while maintaining constant pressure difference to ensure physiological relevance. This dynamic approach improves both reliability of pathophysiological reproduction and measurement precision.
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 enhances the reproducibility and discrimination of blood samples by simulating a range of shear conditions, activating platelets and allowing them to form stable aggregates at physiological shear rates, thereby improving the characterization of platelet aggregation and coagulation processes.
Implementation Method 1
The solution has, during the passage of the front through the inlet of the channel, a shear rate at the internal walls of the channel greater than 10,000 s-1. The solution has, during the progression of the front from the inlet to the outlet of the channel, a shear rate at the internal walls of the channel which decreases over time
Implementation Method 2
The pressure difference between the inlet and outlet of the channel, or a setpoint for this pressure difference, is constant during the progression of the solution through the channel
Implementation Method 3
The passage of the front separating the two liquids produces a change in capacitance between two measuring electrodes, which is measured and allows for the detection and/or characterization of the platelet activation state of the blood sample
Implementation Method 4
The pressure difference between the inlet and outlet of the channel is preferably created by suction on the outlet side of the channel
Data Source
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AI summary
The present invention relates to a process for characterizing a blood sample, comprising: insertion, into a channel, of a solution comprising blood platelets, said channel comprising an inlet and an outlet, the solution being inserted via the inlet of the channel; creating a pressure difference between the inlet and the outlet of the channel so as to cause the solution to progress from the inlet towards the outlet of the channel; passage of the solution into a measurement zone of the channel, provided with electrodes; measurement, by said electrodes and measurement means, of an electric signal while said electrodes are covered by the solution in the channel, characterized in that the progression of the solution from the inlet towards the outlet of the channel comprises a progression of a front between, on the one hand, the solution extending from the front towards the inlet of the channel and, on the other hand, a gas extending from the front towards the outlet of the channel.