Designing Microfluidic Control Components

by Wijngaart, Wouter van

Abstract (Summary)
This work is a microfluidic engineering study. Its overall goal is to create new components and applications through the downscaling of fluidics and to solve technological bottlenecks in this field for better performance of existing solutions. Three specific application areas within microfluidics are studied. A first area is liquid diffuser micropumps. The work focuses on solving one of the main bottlenecks for such micropumps, namely reliability. A new pump design with enhanced bubble tolerance is presented, featuring as the first pump of its kind bidirectional pumping of both gas and liquid with the same device. Moreover, a deeper insight of the flow behaviour in the micropump chamber is given. The device can pump a wide variety of liquids that are of interest in biotechnical applications, and pumping of beads and living cells was shown. The second area this work focuses on is handling and control of on-chip nanolitre liquid volumes. Specifically, a flow-through filter device for bead handling was designed and fabricated. A novel fluidic interface design, a new fabrication method for hydrophobic control elements and a novel fluidic control method are presented, allowing spatial and temporal control of parallel on-chip processes with a minimal device interface. The fabricated devices were successfully used for SNP (single nucleotide polymorphism) analysis with pyrosequencing techniques. The third part of the work is in the area of micro gas handling devices. A novel pneumatic-tomechanical-vibration energy converter concept, intended for wireless energy supply, is presented. The other work performed in the micro gas handling field focuses on cost efficient design of microvalves for large pneumatic energy control. A novel electrostatic large-stroke valve actuator for the control of large pneumatic pressures is presented and investigated. The combination of pressure balancing and flexible electrode structures form the key to the actuator performance. Measurements on test structures confirm the modelled actuator behaviour and predict a significant performance increase compared to earlier electrostatic valve actuators. Another part of the work uses analytic flow predictions and FEA (finite element analysis) to study the gas flow through microvalve nozzles. A novel design, consisting of multiple boss elements and orifices, is proposed. The design allows optimisation of the valveā€™s flow capacity and reduces the actuator stroke that is required. Wouter van der Wijngaart, Microsystem Technology, Department of Signals, Sensors and Systems (S3), Royal Institute of Technology (KTH), SE-10044 Stockholm, Sweden
Bibliographical Information:


School:Kungliga Tekniska högskolan

School Location:Sweden

Source Type:Doctoral Dissertation

Keywords:actuation; beads; bubble; CFD (computational fluid dynamics); diffuser; DNA; electrostatic; energy conversion; FEA (finite element analysis),


Date of Publication:01/01/2002

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