Wireless Electronic Structural Surveillance Sensors Using Inductively Coupled Sacrificial Transducers

摘要

In order to monitor the corrosion of the steel reinforcement in concrete we developed our low cost, wireless, battery free, Electronic Structural Surveillance (ESS) corrosion sensors. The ESS sensors use an unpowered embedded resonant L-C tag read by an external reader using an inductively coupled impedance measurement. Our previous embedded sensors use a steel wire which corrodes when the conditions in the concrete promote corrosion. Such a sacrificial transducer in its native environment is the most direct method of monitoring corrosion. In the previous generation design, this transducer was connected directly to the sensor, hence breaching the hermetic seal protecting the sensor circuit. A new transduction scheme will be discussed which incorporates a fully exposed sacrificial transducer element that is inductively coupled to the sensor resonant circuitry, hence providing a non-contact interaction. The strength of the interaction of the fully exposed, sacrificial transduction layer is set by flux screening and mutual inductance effects. This design also allows the transducer to make use of a variety of materials and morphologies.