Catalogus : Recensies
Recensies
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Ingo Kühne Resonante mikromechanische Energiewandler Volume 8 ISBN: 978-3-8322-8291-2 Prijs: 49,80 € / 99,60 SFR |
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| This work focuses on the investigation of resonantly driven micromechanical energy harvesters. They are based on electromechanically coupled spring-mass-systems, converting mechanical vibrations into electrical energy by employing appropriate physical transduction mechanisms, such as the inductive, the piezoelectric and the capacitive principle. These three approaches are compared to each other, especially with respect to electrical energy density, scaling behaviour and microtechnological fabricability. Theoretical considerations lead to the decision to implement both a capacitive and a piezoelectric micromechanical energy harvester. The capacitive energy transducer essentially consists of a mass suspended by silicon springs. This mass simultaneously serves as a movable electrode. A fixed counter electrode completes the variable capacitor. In order to function properly, the parallel-plate capacitor needs to be based electrically. In contrast to existing state of the art a new approach is introduced, employing two different electrode materials with a large difference in their work functions. A periodical mechanical excitation leads to a variation of the electrical energy content within the biased capacitor, thus inducing a current flow, which can be used for driving an external electrical load. For the piezoelectric energy harvester, the concept of a piezoelectric diaphragm with a mass attached to the surface was used and devices were implemented. A mechanical excitation leads to a periodic deflection of the diaphragm caused by the stiffly coupled inertial mass and, thus, to a changing mechanical stress distribution within the diaphragm. This, in turn, induces a periodic charge separation within the piezoelectric diaphragm. The energy generated in this way can be consumed by an external electrical load with appropriate impedance matching. Theoretical model descriptions are established for both types of energy harvesters based on systems of state space equations. On the basis of these models appropriate concepts for the realisation of the energy harvester with MEMS technology are conceived. The capacitive energy transducer consists of a stack of three hermetically bonded wafers (Pyrex-SOI-Pyrex, 100 mm). The piezoelectric energy harvester is manufactured on standard 150 mm wafers. Finally, both types of energy harvesters are characterised by means of impedance measurements and by comprehensive shaker tests. The results prove the functionality of the developed energy harvesters and verify the validity of the respective model description. | |
| Bron: Rezension: 09.11.2009 ETDE - Energy Database des Leibniz-Instituts für Informationsinfrastruktur (FIZ Karlsruhe), production no.: DE09GA154 | |
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