A method and device for detecting an accumulation of a solid material in a vessel that contains at least one fluid phase. The system includes a frame, where the frame is encapsulated by a cover. In another embodiment, the method includes providing a reservoir of the powder and applying to said phosphor powder an electrostatic charge opposite to that of said electrostatic charge on the first surface. The method detects a data access to an external storage medium and writes a copy of the accessed data to a storage location other than the external storage medium. The redundant column select line passes through the first, second, third and fourth bit lines.