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In this work, we present a low-cost sensor system for continuous non-invasive cell growth monitoring, especially for single use bioreactor (SUB) applications. The sensor system is based on a differential transformer. Using this differential setup, the influence of the primary magnetic flux is eliminated from the measuring signal, enabling highly sensitive non-invasive detection of permittivity changes in the culture medium. To evaluate the sensor, E. coli cultivations are performed and the cell density is measured through the polymer foil of a SUB. We found a linear dependency with low data scattering between measuring signal and cell density.

In this work, a novel approach for the detection of mercury vapor in air is presented using differential heat dissipation measurements. Therefore, the temperature difference between an amalgamated and a non-exposed gold film is recorded, while heating both films with identical electrical power. As the amalgam layer lowers the heat dissipation, the amalgamated gold film reaches higher temperatures compared to the non-exposed gold film. Preliminary experiments show a clear dependence of the measured temperature difference on the mercury vapor concentration and the exposition time. Thus, a detection of mercury vapor is generally possible using differential heat dissipation measurements.