A non-invasive and handheld detector for characterizing steel rebars in concrete

We present a portable handheld detector system for non-invasive inspection of steel rebars in concrete structures using pulsed eddy current. A pair of solenoid coils is used for pulse excitation and signal acquisition, respectively. The electronic system comprises of a microcontroller board (for triggering excitation pulse, digitizing and recording received signal, communication with mobile device and computation of depth and thickness of sample), amplifying circuit (to generate high current pulse), acquisition circuit (to amplify and perform signal conditioning of received signal prior to digitization). Features computed from the received time-domain signal are processed on-board for estimating the depth and diameter of the rebars.