Publicação
Feasibility study of EWOD-based pumping mechanism for on-chip valvaless microfluidic applications
| Resumo: | When faced with the miniaturization challenges that mechanical micropumps pose, the current state of the art does not offer a fabrication flow that is CMOS compatible with reasonable sample yield (more then 50pc of the working devices after the fabrication flow) nor compatible with high ionic concentration liquids. To fulfill this gap, this thesis aims at studying the possible use of electrowetting on dielectric (EWOD) as the pumping mechanism behind a valveless on-chip micropump. To achieve this goal, the role of ion concentration in EWOD performance was studied by testing phosphate buffer saline (PBS), com-monly used in place of bodily fluids in testing in terms of ion concentration and molarity, and de-ionized water (DIW) through contact angle (CA) measurements, as well as impedance spectroscopy (IS) tests. Simulation algorithms were created to both simulate the frequency-dependance of EWOD performance of the droplets, and to study the influence of design parameters in final pump performance. Microchips were fabricated in a cleanroom environment and assembled to experimentally test the feasibility of the chosen pumping mechanism. The EWOD performance studies revealed that the higher the ion concentration of the droplet, the higher the achieved CA change when applying the same voltage, and the broader the usable frequency range before reaching its cutoff. The testing of the microchips with an optical microscope was successful in proving the possibility of using EWOD as a flow generation method, with electric actuation resulting in a 15 µm oscillatory motion at the outlet’s liquid-air interface. The main focuses of future studies for this project should be the improvement of the fabrication process and the introduction of an element that stimulates directional flow to the device, effectively turning into a micropump. |
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| Autores principais: | Bonito, Renato Miguel Martins |
| Assunto: | Microfluidics Electrowetting on dielectric On-chip micropump Valveless Ionic concentration. |
| Ano: | 2024 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso embargado |
| Instituição associada: | Universidade Nova de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório Institucional da UNL |
| Resumo: | When faced with the miniaturization challenges that mechanical micropumps pose, the current state of the art does not offer a fabrication flow that is CMOS compatible with reasonable sample yield (more then 50pc of the working devices after the fabrication flow) nor compatible with high ionic concentration liquids. To fulfill this gap, this thesis aims at studying the possible use of electrowetting on dielectric (EWOD) as the pumping mechanism behind a valveless on-chip micropump. To achieve this goal, the role of ion concentration in EWOD performance was studied by testing phosphate buffer saline (PBS), com-monly used in place of bodily fluids in testing in terms of ion concentration and molarity, and de-ionized water (DIW) through contact angle (CA) measurements, as well as impedance spectroscopy (IS) tests. Simulation algorithms were created to both simulate the frequency-dependance of EWOD performance of the droplets, and to study the influence of design parameters in final pump performance. Microchips were fabricated in a cleanroom environment and assembled to experimentally test the feasibility of the chosen pumping mechanism. The EWOD performance studies revealed that the higher the ion concentration of the droplet, the higher the achieved CA change when applying the same voltage, and the broader the usable frequency range before reaching its cutoff. The testing of the microchips with an optical microscope was successful in proving the possibility of using EWOD as a flow generation method, with electric actuation resulting in a 15 µm oscillatory motion at the outlet’s liquid-air interface. The main focuses of future studies for this project should be the improvement of the fabrication process and the introduction of an element that stimulates directional flow to the device, effectively turning into a micropump. |
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