A removal composition and process for removing low-k dielectric material, etch stop material, andor metal stack material from a rejected microelectronic device structure having same thereon. The apparatus includes a bio material reacting unit, an optical source unit, and a detecting unit. The second gear is disengagable from the first gear by action of the cam assembly, which is adapted to disengage the second gear from the first gear through eccentric rotation of the cam assembly. The synchronization is accomplished by periodically scanning the database to see if any data has changed.