Disclosed is a device for detecting bioelectric signals from spheroids comprising a measuring chamber having a measuring chamber wall which encloses a volume, which is open at least at one side, is composed of an electrically non-conducting material, and has, in at least one measuring region, an inner cross section, which corresponds as far as possible to the largest cross section of a spheroid, comprising at least a number of electrodes which are disposed in a common plane inside said measuring chamber wall and each electrode has a freely accessible electrode surface which is oriented towards the measuring region, and comprising an impedance measuring arrangement which is connected to the electrodes. The device and the method can be used to test substances in 3D biological in-vitro (three-dimensional) cell aggregates.