The invention relates to a device for detecting charged macromolecules, comprising an ion-sensitive layer, on the surface of which a sample molecule is immobilized in order to detect a target molecule, the sample molecule and target molecules that are to be detected being able to create a specific bond. The inventive device is characterized in that the sample molecules are immobilized at a minimum distance from each other on the ion-sensitive layer such that a redistribution of the zone concentration is induced in the intermolecular interstices during bonding with the target molecule. Also disclosed is a method for detecting charged macromolecules with the aid of the inventive device.