We report on the development of a new technology for the fabrication of Micro-Electro-Mechanical-System (MEMS) strain sensors to realize a novel type of crackmeter for health monitoring of ageing civil infrastructures. The fabrication of micromachined silicon MEMS sensors based on a Silicon On Insulator (SOI) technology, designed according to a Double Ended Tuning Fork (DETF) geometry is presented, using a novel process which includes a gap narrowing procedure suitable to fabricate sensors with low motional resistance. In order to employ these sensors for crack monitoring, techniques suited for bonding the MEMS sensors on a steel surface ensuring good strain transfer from steel to silicon and a packaging technique for the bonded sensors are proposed, conceived for realizing a low-power crackmeter for ageing infrastructure monitoring. Moreover, the design of a possible crackmeter geometry suited for detection of crack contraction and expansion with a resolution of 10 and very low power consumption requirements (potentially suitable for wireless operation) is presented. In these sensors, the small crackmeter range for the first field use is related to long-term observation on existing cracks in underground tunnel test sections.
Key Words
structural monitoring; cracks; MEMS; wireless.
Address
Matteo Ferri and Fulvio Mancarella; Institute of Microelectronics and Microsystems (IMM), National Research Council of Italy, Via Gobetti 101, I-40129 Bologna, Italy Ashwin Seshia, James Ransley and Kenichi Soga; Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, UK Jan Zalesky; Czech Technical University in Prague, Faculty of Civil Engineering, Thakurova 7, 166 29 Prague, Czech Republic Alberto Roncaglia; Institute of Microelectronics and Microsystems (IMM), National Research Council of Italy, Via Gobetti 101, I-40129 Bologna, Italy
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