Thermal flow sensors rely on temperature sensors, to evaluate the flow dependent temperature distribution around one or more heat sources. Three main types of thermal flow sensors can be distinguished: calorimetric flow sensors, hot-wire or hot-film sensors, and time-of-flight flow sensors. A starting point of this work was a calorimetric flow sensor, that exploits miniaturized thermistors made of amorphous germanium (aGe) as temperature sensors. These thermistors exhibit a very high temperature coefficient of resistance (TCR) of about -2 %/K. Therefore, they seem to be a good alternative to common metal resistors characterized by much lower TCR. One goal of this work was to investigate the suitability of aGe-thermistors for other types of thermal flow sensors, such as hot-film sensors. Another aim was to find out, whether the properties of the existing calorimetric flow sensor could be improved by implementing alternative operating modes with appropriate electronic circuits.