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uni'wissen 02-2013_ENG

Measurement and control technology is like riding a bicycle: Once you succeed in coor- dinating sight and steering with each other, the process works,” says Prof. Dr. Leo Reindl, head of the Laboratory for Electrical Instrumentation at the Department of Microsystems Engineering of the University of Freiburg. “The better you can get the sensor – the sight – and the actor – the steering – to work together, the more efficiently the system will function.” Developers see great potential in regulation – that is, the coordination between sensor and ac- tor – for making daily life easier, protecting the environment, saving energy, and making work routines safer. “In a world with limited material and energy resources and environmental bur- dens, regulation is the only way to achieve an optimal process. We need sensors and comput- ers for these regulators that we can embed into the process.” Driving a car, for example, has be- come much safer thanks to the integration of roughly 100 regulators for airbags, autonomous cruise control and lane departure warning sys- tems, blind spot monitors, and breaking assis- tants. According to the German automobile club ADAC, the number of deaths due to automobile accidents has sunk continuously since 1970, de- spite the fact that traffic density has increased in the same period. But the field of research Reindl is focusing on is more complex: He is studying how processes can be regulated optimally even when sensor “In a world with limited material and energy resources and environmental burdens, regulation is the only way to achieve an optimal process” and actor are not connected by a cable. Under normal circumstances, the cable maintains the flow of information between sensor and actor and also provides the energy the actor needs to control the system. However, oftentimes it is ei- ther too expensive or simply impossible to link the two elements by cable, because they are in motion or are located too far apart from each other. This is the case, for instance, when one needs to determine the current position of a ro- bot in a building, obtain information on the state of precision workpieces being transported on a conveyor belt, measure the temperature of a high-tension power line or the pressure in an au- tomobile tire, or take measurements inside of a living organism. In addition, cables are inconve- nient when one is monitoring the structural integ- rity of bridges or buildings or analyzing soil composition for agriculture. In these cases, it is necessary to use sensors that transmit data by radio. This presents new challenges for the sys- tem, especially with regard to ensuring a suffi- cient supply of energy. Harvesting Energy from the Environment When the cable is missing, so is the power. There are two ways to solve this problem: attach- ing a battery or enabling the system to harvest energy directly from the environment with the help of a miniature power station. Promising can- didates are light energy, thermal energy, vibra- tional energy, and the electromagnetic radiation present everywhere on Earth. In order to devel- 17