Microfluidic systems and structures are of interest in many technical application areas, for example in medical engineering and biotechnology. For the cultivation of plant cells, however, they are still rarely used, although there is great potential for the production and extraction of secondary metabolites for drug production. However, many of these metabolites are of interest to pharmaceutics. But often their biotechnological production in batch cultures does not meet with success because the dynamic interaction between different types of cells which is necessary for the metabolite formation in the plant is not imaged technically. Scientists at KIT have developed a microfluidic reactor that overcomes this limitation and thus facilitates the development of biotechnological processes. The reactor enables the development of pharmaceutically active contents via plant cell fermentation. In addition to the production of agents against diseases such as cancer and Alzheimer's, pest control agents are a further field of application. With the aid of the microfluidic bioreactor using polymer-based modules coupled to one another, the scientists are technically mimicking complex plant tissues. In each individual module, a cell type or a certain phase of production is processed. The modules are linked via channels. The resulting substances, including metabolic products of a certain cell type, can thus enter the next module and be further processed there without the different types of cells mixing with one another. The target substance can ultimately be extracted from the flow. The individual modules can be combined in different ways, similar to an assembly kit system. The micro-reactor can be used as a process-optimising tool before the stage of large-scale application in order to gain insights regarding the effectiveness and the toxicological properties of the planned target substance in analyses in advance.