Biosensors are used wherever exact monitoring of analytes is relevant in the smooth operation of chemical processes, for instance in environmental, food and biomedical applications. These sensors use a biological component, such as bacteria, which responds to the concentration of a chemical substance by generating optical or electronic signals. The Institute for Applied Biology of the KIT has developed an electronic biosensor unique because of its easy application and high accuracy, which make it clearly different from conventional electronic and optical biosensors. The invention allows inexpensive detection of substances by means of a current transmitted without a mediator to a low-cost graphite electrode. The scientists have developed special bacteria with a "sense" for tracing specific substances, such as the arabinose sugar. These bacteria live on a special type of respiration in which electrons are not transmitted to oxygen, as in humans, but to electrodes. When these organisms breathe, they produce an electric current. The scientists have advanced these bacterial strains so as to make them breathe more or less in the presence, and as a function, of the concentration of specific substances and, in this way, also produce more or less current. As bacteria are able to detect a multitude of different substances, these sensors are extremely flexible. It is only necessary to connect "genetically" the information for detection and the module for respiration. This principle can also be extrapolated to a large number of other analytes, which makes the sensor useful in a variety of ways. The scientists are working on developments up to the quantitative detection of fatty acids. This would allow the sensor to be used in biogas generation. In that case, specific fatty acids would be a clear signal of a process disturbance, which could cause high costs. However, so far there has not been an established inexpensive solution for the detection of these fatty acids.