Chair Electrical Measurements and Sensor Technology
Prof. Dr.-Ing. Olfa Kanoun
Phone+49 (0)371 531 36931
Fax+49 (0)371 531 24529
Main research topics
- Impedance spectroscopy for materials and sensor systems
- Impedance sensors (conductive, capacitive, inductive)
- Battery diagnosis (SoH, SoC, SoF)
- Cable diagnostics and fault localization
- Bio-impedance spectroscopy
- Energy aware wireless sensor system
- Availability and conversion of ambient energy
- Energy management for solar cells
- Vibration energy converters
- Wireless sensor networks for environmental applications
- Flexible sensors based on nanocomposites
- Strain and pressure sensors based on nanocomposites
- Infrared detectors based on nanocomposites
- Sensors at the periphery of human bodies
Extended description of Research topics
The research activities at the chair for measurement and sensor technology (MST) have a strategic focus on the improvement of measurement and sensor principles, the design of smart sensor systems and the model-based signal processing. The research topics are organized in three major topics focusing on impedance spectroscopy, energy aware wireless sensors and flexible sensors based on nanocomposites.
With the aid of impedance spectroscopy the dependence of the complex impedance on frequency is used to detect and investigate effects with variable frequency dependence. This results in an increased amount of measured data containing more information. By the help of advanced data analysis algorithms and model based approaches these information are made accessible. The use of this method in sensor systems exhibits a special challenge due to limited resources, the influence of changing usage conditions and the necessity of non-monitored online signal processing. Our research activities using this method focus on the investigation of cables, biological tissues, materials, energy storage devices and sensor systems. In the field of energy aware wireless techniques and methods are being developed to power systems with ambient energy from the environment. The autonomy of a stationary energy source of an electrical system enables the usability of sensors systems in various usage conditions. This allows a flexible use in harsh fields of application or areas which are difficult to access and reduces the installation and maintenance effort. In mobile applications the space and weight for batteries is being reduced or they will be left out completely.
Ambient sources are investigated for energy supply, such as ambient temperature, light, vibration or air flow. The energy out of those sources is converted into electrical energy which supplies the electrical system. Thereby the focus is on special energy-saving electronics. The circuits shall have various operation modes and profit from often sleep mode. A key role plays the energy management system, which administrates the distribution of energy between storage and application. Depending on the energy balance and the demands of an application, different modes of operation shall be used to minimize the overall consumption.
Nanomaterials such as carbon nanotubes (CNTs) and graphene are promising candidates for different sensor applications. In macroscopic films CNTs form a conductive network at low filler concentration ratios. Carbon nanotubes/graphene oxide nanocomposites showed excellent optical properties and can be used as optical sensor e.g. in the infrared spectrum. The overall resistance of CNT/polymer resistor network changes under applied mechanical load. This effect can be used for applications as strain sensor. Such devices exhibit a higher sensitivity than common metallic strain sensors. Strains in CNT or graphene based flexible sensors can be even measured wirelessly by measuring the change in the complex impedance of a coupled coil.
A highlight in 2014 is the strengthening of the equipment of the chair with a multifunctional impedance spectroscopy equipment combining an atomic force microscope with impedance spectroscopy. This allows us to characterize materials down to the nanoscale with frequencies up to the microwave spectrum by combining electrical properties and topographical properties.
The International Workshop on Impedance Spectroscopy is taking place for the 7th time, which is established and successfully organized by Prof. Kanoun and her staff.