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Thermo-responsive poly(ionic liquid) valves for microfluidic devices

Tudor, Alexandru and Saez, Janire and Florea, Larisa and Benito-Lopez, Fernando and Diamond, Dermot (2016) Thermo-responsive poly(ionic liquid) valves for microfluidic devices. In: BioEl2016 3rd International Winterschool on Bioelectronics, 12-19 Mar 2016, Kirchberg am Tirol, Austria.

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Poly(ionic liquid)s (PIL) are a class of ionic liquids that feature polymerizable groups in the cation, the anion or both. They retain most of the properties present in ionic liquids, including ionic conductivity, low vapour pressure and tunable physico-chemical properties. Several phosphonium ionic liquids have been shown to possess a lower critical solution temperature, making them suitable materials for the synthesis of temperature-responsive smart materials.1,2 Herein, we present the synthesis of a thermo-responsive tributylhexyl phosphonium 3-sulfopropyl acrylate (PSPA) crosslinked PIL, followed by its inclusion in a microfluidic device to be used as a temperature controlled valve. After polymerization, the hydrogels were swollen in deionized water and had their temperature-induced shrinking measured with a digital microscope from 20 °C to 70 °C, in 10 °C intervals. Measurements indicate a relative surface contraction of the hydrogels, in deionized water, of 34.04% ± 4.62% (n = 3) at a temperature of 50 °C, and 53.37% ± 12.55% (n = 3) at a temperature of 70 °C. Following this, microfluidic devices were constructed using poly(methyl methacrylate) and pressure sensitive adhesive. After assembly, the chips were fitted on a heating element and connected to a syringe pump with a flow rate of 500 nL·min-1. A flow microsensor was used to analyze the shrinking-swelling efficiency of the PILc hydrogel valves. A temperature of 50 °C was applied to shrink the hydrogels, followed by a temperature of 25 °C to re-swell the hydrogels. The time required for the PILc valve to open was ~6s, allowing water flow (~140 nL·min-1), while the time required for it to close was ~10s. This process was repeated for six times indicating the possibility of using these valves for multiple times. In conclusion, the results confirm the applicability of PSPA hydrogels as thermally controlled valves in microfluidic devices. Furthermore, the next steps of this study will focus on the optimization of the microfluidic device to ensure maximum efficiency in closing and opening the channel, while also increasing the repeatability of the operation.

Item Type:Conference or Workshop Item (Invited Talk)
Event Type:Conference
Uncontrolled Keywords:Polymer Chemistry; Polymers; Stimuli-responsive polymers; Temperature-responsive polymers; ionic liquids; poly(ionic liquid)s
Subjects:Physical Sciences > Organic chemistry
Physical Sciences > Chemistry
DCU Faculties and Centres:DCU Faculties and Schools > Faculty of Science and Health > School of Chemical Sciences
Research Initiatives and Centres > INSIGHT Centre for Data Analytics
Research Initiatives and Centres > National Centre for Sensor Research (NCSR)
Use License:This item is licensed under a Creative Commons Attribution-NonCommercial-Share Alike 3.0 License. View License
ID Code:21181
Deposited On:11 May 2016 10:38 by Alexandru Tudor. Last Modified 11 May 2016 10:38

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