  Current detection and identification of micro-organisms is based on either
rather unspecific rapid microscopy or on more accurate complex, time-consuming
procedures. In a medical context, the determination of the bacteria Gram type
is of significant interest. The diagnostic of microbial infection often
requires the identification of the microbiological agent responsible for the
infection, or at least the identification of its family (Gram type), in a
matter of minutes. In this work, we propose to use terahertz frequency range
antennas for the enhanced selective detection of bacteria types. Several
microorganisms are investigated by terahertz time-domain spectroscopy: a fast,
contactless and damage-free investigation method to gain information on the
presence and the nature of the microorganisms. We demonstrate that plasmonic
antennas enhance the detection sensitivity for bacterial layers and allow the
selective recognition of the Gram type of the bacteria.
