Multi-parametric, label-free and non-contact approach to bacteria single-cells and biofilm formation detection

Understanding the mechanism of biofilm formation is essential to progress in the field of microbiology and infection control. Here we demonstrate a new approach to detect bacterial single cell and biofilms using label-free and non-contact methods. Multimode measurements using Kelvin probe, digital holographic tomography and infrared microscopy were performed on E. coli cells. The proposed analysis provides the multi-parametric detection of bacteria based on contact potential difference, refractive index data and infrared spectra related to electrical, optical, morphological, and chemical properties of the single cells. Moreover, it is the first attempt to use the Kelvin Probe and contact potential difference measurements for bacteria sensing. The obtained results confirmed that it is possible to use the mentioned above techniques for examination of the biofilm formation. Furthermore, it was confirmed that after only 24 hours E. coli bacteria formed biofilm on the analyzed surfaces without the presence of any nutrients.