A device for fragmenting ions by collision induced dissociation, the device intended to be used together with a planar ion mobility apparatus, the device including a first conductive grid having a plurality of first openings, the first conductive grid configured for electric interconnection to a first electric potential, and a second conductive grid having a plurality of second openings, the second conductive grid configured for electric interconnection to a second electric potential, the first and second conductive grids being electrically insulated from each other.