[Integrated optical sensor for rapid analysis of biological samples].

INTRODUCTION: In the medical diagnostics of bacteria, the rapid detection of pathogenic microorganisms from body fluids is one of the most important tasks. The majority of the modern measuring techniques are based on specific labels bound to the bacteria. However, this strategy usually assumes a rather time-consuming procedure involving several steps (e.g., the widely used enzyme-linked immunosorbent assay normally consists of 5 consecutive steps). Hence, there is an urgent need for the elaboration of rapid, "label-free" techniques, that are often based on Lab-on-a-chip devices. AIM: In this paper, the authors report on the development of a biosensor based on a miniature, integrated optical Mach-Zehnder interferometer. METHOD: Functionalization of the measuring arm of the sensor by antibodies, made the rapid and specific label-free detection of pathogens feasible. RESULTS: Using the combination of the interferometer with a microfluidic system, the device was able to detect Escherichia coli bacteria at concentrations as low as 10(6) colony forming unit/ml within minutes. CONCLUSIONS: This makes the newly developed biosensor a promising device for a wide range of applications, not only in medical microbiology, but microbial forensics, criminal investigations, bio-terrorism threats and in environmental studies as well.