Diffusion-free valve for preprogrammed immunoassay with capillary microfluidics
Abstract By manipulating the geometry and surface chemistry of microfluidic channels, capillary-driven microfluidics can move and stop fluids spontaneously without external instrumentation. Furthermore, complex microfluidic circuits can be preprogrammed by synchronizing the capillary pressures and e...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Nature Publishing Group
2023-07-01
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| Series: | Microsystems & Nanoengineering |
| Online Access: | https://doi.org/10.1038/s41378-023-00568-2 |
| _version_ | 1797774143920275456 |
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| author | Pooya Azizian Jasmina Casals-Terré Jordi Ricart Joan M. Cabot |
| author_facet | Pooya Azizian Jasmina Casals-Terré Jordi Ricart Joan M. Cabot |
| author_sort | Pooya Azizian |
| collection | DOAJ |
| description | Abstract By manipulating the geometry and surface chemistry of microfluidic channels, capillary-driven microfluidics can move and stop fluids spontaneously without external instrumentation. Furthermore, complex microfluidic circuits can be preprogrammed by synchronizing the capillary pressures and encoding the surface tensions of microfluidic chips. A key component of these systems is the capillary valve. However, the main concern for these valves is the presence of unwanted diffusion during the valve loading and activation steps that can cause cross-contamination. In this study, we design and validate a novel diffusion-free capillary valve: the π-valve. This valve consists of a 3D structure and a void area. The void acts as a spacer between two fluids to avoid direct contact. When the valve is triggered, the air trapped within the void is displaced by pneumatic suction induced from the capillary flow downstream without introducing a gas bubble into the circuit. The proposed design eliminates diffusive mixing before valve activation. Numerical simulation is used to study the function and optimize the dimensions of the π-valve, and 3D printing is used to fabricate either the mould or the microfluidic chip. A comparison with a conventional valve (based on a constriction-expansion valve) demonstrates that the π-valve eliminates possible backflow into the valve and reduces the mixing and diffusion during the loading and trigger steps. As a proof-of-concept, this valve is successfully implemented in a capillary-driven circuit for the determination of benzodiazepine, achieving the successive release of 3 solutions in a 3D-printed microfluidic chip without external instrumentation. The results show a 40% increase in the fluorescence intensity using the π-valve relative to the conventional value. Overall, the π-valve prevents cross-contamination, minimizes sample use, and facilitates a sophisticated preprogrammed release of fluids, offering a promising tool for conducting automated immunoassays applicable at point-of-care testing. |
| first_indexed | 2024-03-12T22:16:40Z |
| format | Article |
| id | doaj.art-3d096a5a21ac4ef3b0bc038508ce6526 |
| institution | Directory Open Access Journal |
| issn | 2055-7434 |
| language | English |
| last_indexed | 2024-03-12T22:16:40Z |
| publishDate | 2023-07-01 |
| publisher | Nature Publishing Group |
| record_format | Article |
| series | Microsystems & Nanoengineering |
| spelling | doaj.art-3d096a5a21ac4ef3b0bc038508ce65262023-07-23T11:17:19ZengNature Publishing GroupMicrosystems & Nanoengineering2055-74342023-07-019111310.1038/s41378-023-00568-2Diffusion-free valve for preprogrammed immunoassay with capillary microfluidicsPooya Azizian0Jasmina Casals-Terré1Jordi Ricart2Joan M. Cabot3Energy and Engineering Department, Leitat Technological CenterMechanical Engineering Department, Technical University of CataloniaEnergy and Engineering Department, Leitat Technological CenterEnergy and Engineering Department, Leitat Technological CenterAbstract By manipulating the geometry and surface chemistry of microfluidic channels, capillary-driven microfluidics can move and stop fluids spontaneously without external instrumentation. Furthermore, complex microfluidic circuits can be preprogrammed by synchronizing the capillary pressures and encoding the surface tensions of microfluidic chips. A key component of these systems is the capillary valve. However, the main concern for these valves is the presence of unwanted diffusion during the valve loading and activation steps that can cause cross-contamination. In this study, we design and validate a novel diffusion-free capillary valve: the π-valve. This valve consists of a 3D structure and a void area. The void acts as a spacer between two fluids to avoid direct contact. When the valve is triggered, the air trapped within the void is displaced by pneumatic suction induced from the capillary flow downstream without introducing a gas bubble into the circuit. The proposed design eliminates diffusive mixing before valve activation. Numerical simulation is used to study the function and optimize the dimensions of the π-valve, and 3D printing is used to fabricate either the mould or the microfluidic chip. A comparison with a conventional valve (based on a constriction-expansion valve) demonstrates that the π-valve eliminates possible backflow into the valve and reduces the mixing and diffusion during the loading and trigger steps. As a proof-of-concept, this valve is successfully implemented in a capillary-driven circuit for the determination of benzodiazepine, achieving the successive release of 3 solutions in a 3D-printed microfluidic chip without external instrumentation. The results show a 40% increase in the fluorescence intensity using the π-valve relative to the conventional value. Overall, the π-valve prevents cross-contamination, minimizes sample use, and facilitates a sophisticated preprogrammed release of fluids, offering a promising tool for conducting automated immunoassays applicable at point-of-care testing.https://doi.org/10.1038/s41378-023-00568-2 |
| spellingShingle | Pooya Azizian Jasmina Casals-Terré Jordi Ricart Joan M. Cabot Diffusion-free valve for preprogrammed immunoassay with capillary microfluidics Microsystems & Nanoengineering |
| title | Diffusion-free valve for preprogrammed immunoassay with capillary microfluidics |
| title_full | Diffusion-free valve for preprogrammed immunoassay with capillary microfluidics |
| title_fullStr | Diffusion-free valve for preprogrammed immunoassay with capillary microfluidics |
| title_full_unstemmed | Diffusion-free valve for preprogrammed immunoassay with capillary microfluidics |
| title_short | Diffusion-free valve for preprogrammed immunoassay with capillary microfluidics |
| title_sort | diffusion free valve for preprogrammed immunoassay with capillary microfluidics |
| url | https://doi.org/10.1038/s41378-023-00568-2 |
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