The research in the area of microelectronic fluidic (MEF) devices for biomedical applications is rapidly growing. As faults in these devices can have severe personal implications, a system is presented which includes fault-tolerance with respect to the systhesized biomaterials (peptides). It can employ purity detection of peptides via current tests of control electrodes of impedance measurements using direct sensing electrodes near the peptide collector area. In the case of purity problems, the location is marked, and repeated synthesis at another collector side is initiated.