Design eines Probeneingabemoduls für einen Mikrofluidikchip zur Detektion von Folsäure

The aim of this study was to design, to produce and to evaluate a pre-treatment module for measuring folic acid in human blood by using a microfluidic chip. The measurement of folic acid is done with optical spectroscopy. In human blood, however, the presence of hemoglobin interferes with the optical detection of folic acid. With this in mind, a method which combines the introduction of whole human blood into the microchannel structure of a microfluidic chip, so-called macro-to-micro interface, and the separation of the red blood cells was designed. The cell-reduced suspension can then be analyzed for folic acid.



The separation of red blood cells on a microfluidic chip is based on purely physiological flow effects. Three different processes for creating the chip (hot embossing, milling, polymer prototyping) were investigated. The milled-channel method gave the best results and was therefore preferred for use. Also the effect of channel structure and geometries on the separation efficiency was examined. With the optimized chip it was possible to generate 10 µL of separated (cell-reduced) suspension containing three times less hemoglobin than whole blood. It was shown that the used materials did not adsorb erythrocytes, hemoglobin or folic acid. The macro-to-micro interface was chosen because of the high pressures involved in the separation method. Thus, in this proof of concept study, it was shown that it is possible to separate red blood cells from whole blood in a microfluidic chip for the purpose of measuring folic acid. The production of the microfluidic chips was improved over time.