Disputas: Zhaochu Yang
M.Sc. Zhaochu Yang ved Matematisk institutt vil forsvare sin avhandling for graden ph.d.: Microfluidic sensing and power generation with coplanar interdigital capacitors
Tid og sted for prøveforelesning
Professor Yumei Wen, Chongqing University
Senior Research Scientist Conor O'Mahony, Tyndall National Institute
Førsteamanuensis Murat Tutkun, Universitetet i Oslo
Leder av disputas
Professor John Grue, Matematisk institutt, Universitet i Oslo
- Professor Einar Halvorsen, Institutt for mikro- og nanosystemteknologi, Høgskolen i Buskerud og Vestfold
- Førsteamanuensis Tao Dong, Institutt for mikro- og nanosystemteknologi, Høgskolen i Buskerud og Vestfold
- Professor Atle Jensen, Matematisk institutt, Universitetet i Oslo
Transduction and sensing for microfluids have attracted numerous interests from the diverse research fields. Interdigital capacitance comprising of interdigital electrodes (IDEs) and thin insulation film provides a feasible solution for microfluidic transduction. This thesis explores the promising applications of interdigital capacitance for microfluidic generation and sensing.
The fluidic electrostatic energy harvester employing conductive droplet rolling through interdigital capacitor is demonstrated in this work. A very thin electret PTFE (Polytetrafluoroethylene) film was achieved with charges embedded during the sputtering process. Mercury droplets as well as ionic liquid marbles rolling across the interdigital capacitor are demonstrated to generate power. With a 1.2-mm mercury droplet rolling across the interdigital capacitor of the prototype, a maximum output power was obtained at 0.18 μW and the peak value of the output voltage was 1.5 V, which is in a suitable range to be dealt with by power conversion electronics and energy storage.
A prototype of microfluidic flow pattern sensor, which is capable of detecting presence of different flow patterns, e.g., droplet flow, short slug flow and long slug flow of olive oil-water two-phase flow in microchannels, has been demonstrated. Time-dependent capacitance variation corresponding to each flow pattern were obtained from the prototype, which can be used to determine both velocity and size of the flow regime due to that the sensing length of the sensor is known. This microfluidic flow sensor can identify typical two-phase flow patterns, comprising of two immiscible fluids whose relative permittivities are remarkably different, no matter liquid-liquid flow, or gas-liquid flow, even vapor-liquid flow.
It is consequently concluded that interdigital capacitance is very promising for microfluidic generation and sensing, owing to the coplanar configuration, which is compatible to the general microfabrication processes, and its sensing capability of non-invasive feature during operation.
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