Impedance spectroscopy measurements in microfluidic environment

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Dr. Juhász László
Department of Electron Devices


In accordance with the monumental progression of microelectronics, the user disciplines of its toolbar are also accomplished serious developments in the last decades. The con-tinuous crossings of the technological limitations lead to the radical integration and miniaturization of the applied devices. Within the MEMS devices, belongs to this cate-gory, the bioanalytical devices, which also use microfluidics and sensors.

Beside the developments of the industry, the pollution of the environment also got in the center of attention. The contamination caused greenhouse effect, and the transformation of our environment, helped the spread of weeds. The higher concentration of soot, and pollens in the air caused the deterioration of the air quality, which in this case helped the increase of the allergic and upper respiratory diseases. To solve this problem, and repair the purity of the air, several countries commit themselves with agreements, and help its fulfillments with tenders.

It shows the importance of the topic, that while the Hungarian government with the PM10 reduction program, the organization of European countries, called Euripides2, encourages the improvement of the air quality, with tender sources.

During my work, I joined the air quality monitoring project, of the Institute of Technical Physics and Materials Science. I got to know the method of electrochemical impedance spectroscopy, and according to this, the potentiostat of the institute. I got a deeper in-sight of the microfluidic, and measurement technology which can be implemented in the institute.

Designed and followed through the manufacturing of microfluidic chips, and planned, and applied fitting measurement techniques to them, in aware of the related literature, the available equipment and the technological opportunities.

Tested different opportunities, both technological, microfluidic and measurement point of views. Verified the operability of the opportunities, and in aware of its advantages and disadvantages, applied new solutions, in the design of the chips, and the develop-ment of the system.

In my thesis I present these fluidic, and measurement opportunities, their realization, and efficiency. During the measurements, from the project’s point of view, I experi-enced positive and negative features, so I made changes to use, or eliminate them in the future.

From a technological point of view, I designed and tested glass, silicon, polymer and their combinations, to optimize it to the project.

From a microfluidic point of view, I tested different focusing methods and its efficien-cy, and expanded the applied fluid manipulating methods with sorting, since this kind of variety of the particles size and structure, have advantages to integrate it into the device.

From a measurement point of view, I tested the operability of the system, with potenti-ostat, its substitution, and because of the occurring noise, concentrated to noise filtering, so I also tested with measurement assemblies using the principle of lock-in amplifiers.


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