Multi-parameter detection for supporting monitoring and control of biogas processes in agriculture

Konferenz: Sensoren und Messsysteme 2014 - Beiträge der 17. ITG/GMA-Fachtagung
03.06.2014 - 04.06.2014 in Nürnberg, Deutschland

Tagungsband: Sensoren und Messsysteme 2014

Seiten: 5Sprache: EnglischTyp: PDF

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Huck, Christina; Poghossian, Arshak; Schoening, Michael J. (Institute of Nano- and Biotechnologies, FH Aachen, Campus Juelich, Juelich, Germany)
Buniatyan, Vahe V. (Department of Microelectronics and Biomedical Devices, State Engineering University of Armenia, Yerevan, Armenia)
Wagner, Patrick (Institute for Materials Research, Hasselt University, Belgium)

The biogas production process is influenced by numerous microbiological, chemical and physical quantities. Disturb-ances known to occur can be due to overload of the biology, lack of macro- and micro-nutrients as well as entry of inhibitors. Process control requires therefore the acquisition of a variety of measures to guarantee a stable process operation, optimization and high yield. In this work, two micro-machined sensor chips for the detection of the early warning indicator dissolved hydrogen and the state variables electrolyte conductivity, pH value and temperature are presented. The first sensor chip is a one-chip integrated, combined amperometric/field-effect sensor for monitoring the dissolved hydrogen concentration. The combination of two different transducer principles might allow a more accurate and reliable measurement of dissolved hydrogen as an early warning indicator of digester failures. The second sensor chip integrates a capacitively coupled four-electrode electrolyte conductivity sensor, a capacitive field-effect pH sensor and a thin-film Pt-temperature sensor. Barium strontium titanate (BST) is utilized as final coating layer of the processed sensor chip. Due to the multifunctional properties of BST, it serves as passivation and protection layer as well as pH-sensitive transducer material at the same time. The results of testing of the two micro-machined sensor chips are presented.