A measurement technique for the vibrating wire sensors

Wireless sensor networks are becoming a reality in civil engineering. Various features as the low cost, feasibility of being supplied by energy harvesting techniques such as a low maintenance, make wireless sensor nodes a very attractive solution when compared to wired processing units. Vibrating wire strain gauges are a particular class of force transducers very simple to embed in reinforced concrete. Nevertheless, an optimal control of these sensors for the low-power applications, requires a dedicated measurement principle that differs from the proven techniques. In this work, we propose a strain measurement based on the RMS value of the harmonic response. Theoretical calculations and experimental results are also given to demonstrate its validity.