Enhanced Resolution of Passive, Wireless Conductivity Sensors

A passive, wireless sensor has been developed at the University of Texas at Austin to monitor the insitu conductivity of concrete within civil infrastructure systems. Electrical conductivity is one possible indicator of corrosion of embedded reinforcement and thereby provides information on structural performance. The sensors would be attached to the reinforcement cages before placement of the concrete and interrogated as part of a routine inspection over the service life. A new sensor design, a non-contact conductivity sensor, is being developed to minimize the likelihood of damage to the sensor during placement of the concrete; a metal element is positioned above the sensor body but is not connected to the resonant circuit within the sensor. In order to verify the response of the non-contact conductivity sensors, they were submerged in liquids of increasing conductivity. Analysis of the measured data demonstrated that the noncontact conductivity sensors successfully detected conductivity variations in liquids.