Cell-based biosensors can simulate the effect of various substances, such as drugs, on the human body in the laboratory. Depending on the measuring principle, though, producing them can be expensive. As a result, they are often not used. Cost factors for sensors that perform measurements electrically are the expensive electrode material and complex production. Fraunhofer scientists are now producing biosensors with graphene electrodes cheaply and simply in roll-to-roll printing. A system prototype for mass production already exists.
Cell-based biosensors measure changes in cell cultures via electrical signals. This is done by means of electrodes which are mounted inside the Petri dish or the wells of a so-called well plate. If added viruses destroy a continuous cell layer on the electrodes, for example, the electrical resistance measured between the electrodes is reduced. In this way, the effect of vaccines or drugs (for example) can be tested: the more effective the active ingredient is, the smaller the number of cells that are destroyed by the viruses and the lower the measured resistance change will be. Also toxicity tests, such as on cosmetic products, can function according to the same principle and may replace animal experiments in the future. Another advantage: If biosensors are linked to an evaluation unit, measurements can be continuous and automated.
Conductive, biocompatible, printable
The preparation of the described biosensors is expensive and complex, though: the electrodes are made of a biocompatible and electrically conductive material, such as gold or platinum. The production of microelectrodes requires a complicated lithographic process. The result: The laboratories often do not buy these biosensors because of the high costs, and the examination of the cell cultures continues to be performed manually under a microscope. As an alternative to precious metals, however, graphene can now be used as a material for the electrodes. The advantages of the carbon material: it is electrically conductive, biocompatible and, if in the form of an ink, can be printed on surfaces.
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