The focus of this project is to find a suitable method to determine the mixing ratio inbinary fluid mixtures in continuous-flow microfluidic systems because of thedifficulties in doing so for mixtures containing compressible fluids. Refractive indexand relative static permittivity are both properties that could be suitable, but methodsmeasuring the refractive index scales badly for microsystems. A microfluidic chip for measuring capacitance was placed on a PCB together with amixing structure with strain-relieved fluid and electrical interfaces. This PCB was builtinto a rig with two piston pumps and a backpressure regulator to makemeasurements of the relative static permittivity of air, ethanol, methanol, acetonitrile,liquid and gaseous carbon dioxide, as well as of several mixtures of ethanol andcarbon dioxide using a Network Analyzer. Several other measuring techniques were tried, but the Network Analyzer wassuperior in accuracy, stability and frequency range. It produced values within 4% ofthe theoretical, and the discrepancy could be explained by the approximations in theparallel plate capacitor formula, the capacitance contributions of the external parts ofthe system and surface roughness. The Network Analyzer is a good tool to determinethe mixing ratio in binary fluid mixtures in continuous-flow microfluidic systems.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:uu-324869 |
| Date | January 2017 |
| Creators | Wilson, Anton |
| Publisher | Uppsala universitet, Mikrosystemteknik |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | UPTEC F, 1401-5757 ; 17031 |
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