Corrosion is a major problem for civil infrastructure and is one of the leading factors in infrastructure deterioration.
Techniques such as half-cell potential can be used to periodically monitor corrosion, but can be difficult to reliably
interpret. Wired systems have large installation cost and long-term reliability issues due to wire corrosion. In this paper
an embedded inductively coupled coil sensor able to monitor the corrosion potential of reinforcement steel in concrete is
presented. The sensor is based on a coil resonator whose resonant frequency changes due to the corrosion potential being
applied across a parallel varactor diode. The corrosion potential can be monitored externally using an inductively
coupled coil. An accelerated corrosion test shows that it can measure corrosion potentials with a resolution of less than
10 mV. This sensor will detect corrosion at the initiation stage before observable corrosion has taken place. The wireless
sensor is passive and simple in design, making it an inexpensive, battery less option for long-term monitoring of the
corrosion potential of reinforcing steel.