Wireless, passive, resonant-circuit, inductively coupled, inductive strain sensor

This paper presents a non-contact, wireless, passive, inductively coupled strain sensor. The sensor itself is a parallel-connected LC tank circuit. Small geometric changes in a stressed solenoidal inductor were predicted to affect its inductance and as a consequence the resonant frequency of the LC circuit. Using a gate dip meter as a sensitive detector, this was experimentally confirmed. There was found to be a consistent relationship between relative strain with shifted resonant frequency independent of whether the sensor was embedded or not.