Microfluidic Cartridge Segmented Paths for Cross-Contamination
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Solution Overview
Problem
Existing microfluidic sensing devices face challenges in measuring successive liquid samples without cross-contamination, particularly when using pneumatic actuation, which can lead to residue issues and inefficiencies in sample regeneration.
Innovation Solution
A microfluidic sensing device with a waste chamber and restriction organs in the microfluidic paths to manage fluid flow, combining capillary and pneumatic forces for sample handling, ensuring that excess sample is returned to the original container without contamination, and utilizing a cartridge design for simultaneous multi-sample analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If pneumatic actuation is used to evacuate and renew sample in the detection chamber, then the sensor can be reused for successive measurements, but cross-contamination occurs due to sample residues left when positive pressure is applied
Solution Approach 1:
The harmful function of the second microfluidic path (which causes cross-contamination when used for pneumatic evacuation) is extracted and replaced by a dedicated waste chamber. The third microfluidic path is introduced to provide a contamination-free route for sample return, separating the evacuation function from the renewal function.
Solution Approach 2:
The waste chamber acts as an intermediary element that receives and contains sample residues during pneumatic evacuation, preventing them from contaminating the detection chamber. The third microfluidic path serves as an intermediary route that allows clean sample return without passing through the contaminated evacuation path.
2Device complexity
If passive capillary transport is used to transport sample to the detector, then the device is simple and disposable, but the process is irreversible and not suitable for reusable sensors
Solution Approach 1:
The microfluidic system is segmented into multiple independent paths: the first path for sample intake via capillary action, the second path for pneumatic evacuation to waste, and the third path for clean sample return. This segmentation allows the sensor to be reused while maintaining the simplicity of capillary-based operation.
Solution Approach 2:
Pneumatic actuation is introduced through the second and third microfluidic paths to enable reversible sample handling. Negative pressure evacuates samples to the waste chamber, and positive pressure returns excess sample through the third path without contamination, making the sensor reusable while preserving capillary transport simplicity.
3Device complexity
If a unique opening is used for sample entry and exit in a reusable cartridge, then the structure is simplified, but cross-contamination occurs because positive pressure cannot effectively force liquid film out
Solution Approach 1:
The single opening is segmented into multiple separate openings: the first opening for sample entry, the second opening for pneumatic evacuation, and the third opening for clean sample return. This segmentation allows independent control of fluid paths, preventing cross-contamination while maintaining structural simplicity.
Solution Approach 2:
Each opening is assigned a specific function with localized quality: the first opening handles sample intake, the second opening handles evacuation to waste, and the third opening handles clean return. This functional differentiation at each opening prevents cross-contamination while keeping the overall cartridge design simple.
4Duration of action of stationary object
If multiple microfluidic paths with valves and flow resistances are used to reverse liquid flow, then sample regeneration is achieved, but the device complexity increases significantly
Solution Approach 1:
The system uses passive capillary forces in the first microfluidic path for automatic sample intake without requiring active pumping or complex valve control. The pneumatic actuation through the second and third paths provides simple on/off control for evacuation and return, reducing the need for complex flow resistance adjustments and multiple valves.
Solution Approach 2:
The pneumatic actuation system serves multiple functions: negative pressure through the second path evacuates samples to waste, positive pressure through the third path returns excess sample cleanly, and the same actuator can control both functions sequentially. This multi-functionality reduces the need for separate components for each operation.
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 successive measurements on multiple liquid samples without cross-contamination, optimizing sample handling and reducing waste, while simplifying the operation and design compared to prior art devices.
Implementation Method 1
the detector is typically provided in a microfluidic package which will transport a sample from the measured liquid to the detector by means of capillary forces
Implementation Method 2
Applying negative and positive pressure with a pneumatic actuator allows the entry and exit of a small volume liquid sample through a unique opening
Data Source
Figure 1
Figure 2
Figure 3a~3d
AI summary
The invention relates to a microfluidic sensing device (1), for conducting measures on liquid samples, comprising a housing (2) having: - a first opening (12) defining an inlet and/or an outlet for a liquid sample, - a detection chamber (16) comprising an electrochemical sensor (32), - a first microfluidic path (14) connecting the first opening (12) to the detection chamber (16), such that the detection chamber (16) can be filled in with the liquid sample, - a second opening (20) designed so as to allow the application of a negative and/or positive pressure within the housing (2), - a second microfluidic path (18) connecting the second opening (20) to the detection chamber (16), - a third opening (28) designed so as to allow the application of a negative and/or positive pressure within the housing (2), - a third microfluidic path (26) connecting the third opening (28) to the first microfluidic path (14), and - a waste chamber (22) arranged in the second microfluidic path (18).