We are interested in the development, characterization and application of biohybrid systems in neuroscience. The development of biohybrid systems is an interdisciplinary process with close collaboration of biologists and electrical engineers (Institut für Werkstoffe der Elektrotechnik 1, RWTH Aachen University). The systems consist of cells cultured in technical devices. The technical devices consist of multielectrode array (MEA) combined with microfluidic systems. MEAs provide the opportunity to investigate neuronal networks non-invasively for several days or weeks which is not possible with experiments in intact nervous systems. Dependent on the number of electrodes on the MEA signals of different cells can be measured simultaneously. The microfluidic devices consist of channels and chambers of micrometer size. Through these systems smallest amounts of fluid can be conducted. We use primary cell cultures of invertebrate neurons, mainly of the locust Locusta migratoria and the snail Lymnaea stagnalis. Small neuronal networks allow for detailed insight in network activity. Invertebrate neurons are well suited for the investigation of networks at extremely low cell density. The aim of our projects is the development and improvement of neuronal biohybrid systems for the formation of small defined networks consisting of only a small number of neurons.