Comparability of responses to neuroactive compounds and spatially and temporally resolved delivery of soluble factors are two major key features for pharmacological assays. Here, we describe the fabrication and the use of a device for long-term growth of twin neuronal networks and for their controlled biochemicalstimulation. The device is formed by a PDMS microfl uidic chamber coupled to a fl at Microelectrode Array (MEA), which provides the electrophysiological readout of the pharmacological stimulation. A partial physical barrier divides the chamber in two sub-compartments, where two functionally independent but fl uidically connected neuronal networks can be grown. This platform improves biological comparability between cultures and allows to perform selective and temporally controlled stimulations to neurons, running parallel pharmacological tests on the same device.