The development of MEMS strain sensors suited to be employed in the realization of crackmeters for health monitoring of ageing infrastructures is reported. The realized sensors are micromachined silicon resonant structures based on a Silicon On Insulator (SOI) technology, designed according to a Double Ended Tuning Fork (DETF) geometry. Their operating principle relies on the vibrating wire concept, whose implementation in this case consists of a micrometric silicon beam driven into vibration by an applied electrostatic force. The sensors are conceived for employment on a crackmeter steel bar to be used in crack movement monitoring, that should be able to detect crack contraction, expansion or sliding movements within the range 10-100 µm, with high resolution and very low power consumption requirements (suited for potential wireless operation). In the paper, the MEMS sensors design and fabrication is described, along with possible packaging solutions for their effective integration on a crackmeter steel bar, designed in order to match the defined specifications in terms of measurement range.
16 Sep 2009
Volume: 6 Issue: 4 Pages: 225-238
Smart Structures and Systems