Micro Surface Defects Detection by Bacterial Cell Suspension

摘要

Recent developments have shown that the use of bacterial cell suspension may be a non-destructive testing technique viable to detect micro surface defects in engineering materials. This new NDT technique explores the wide range of properties of bacterial cells, such as small dimension, high penetration capacity, motility, adherence, reproducibility and death, and also susceptibility to electric and magnetic fields and the possibility to stain them with fluorescent dyes. The generic methodology to perform this NDT technique is similar to the one used in dye penetrant and magnetic particles techniques. In fact, bacterial cells preferentially adhere to surface irregularities, such as roughness, cracks and voids, allowing the identification of these defects in inspected surfaces. This communication presents results on the application of the technique in samples of different engineering materials to detect artificial micro defects, using two types of bacteria, in the presence or not of magnetic and electric fields. The technique was also validated in micro fabricated samples. The experimental results show that it is possible to identify artificial defects with 20 μm width and 4 μm of depth in AISI 304L, AA1100 and copper.