Complementary Split-Ring Resonator (CSRR)-Loaded Sensor Array to Detect Multiple Cracks: Shapes, Sizes, and Positions on Metallic Surface

Abstract

Single-resonance-based radio frequency (RF) resonators cannot detect multiple cracks simultaneously nor localize the position of a crack. To address these drawbacks, we propose a complementary split-ring resonator (CSRR)-loaded array. In this array, there are four channels and each channel consists of three CSRRs, forming a 4×3 sensing array that is developed in the ground plane of a microstrip line using a low-cost FR4 substrate. A voltage-controlled oscillator (VCO) generates three discrete frequencies: 1.88 GHz, 2.60 GHz, and 3.61 GHz to each channel, which is sequentially selected using a single-pole four-throw (SP4T) switch. The transmitted RF signals are converted into the DC voltage levels and are interpreted by a microcontroller. Aluminum sheets with cracks embedded in the surface are used to demonstrate the detection of cracks of various shapes, sizes and locations/orientations (horizontal, diagonal, and vertical) with simulations and measurements. The detection of the minimum detectable crack (Wc×Lc×Dc = 1 mm × 10 mm × 0.1 mm) is experimentally verified. Full-length longer cracks (Lc = 100 mm) are also detected using our proposed detection system with the SP4T switch in addition to our proposed algorithm that scans the CSRRs of each selected channel.

Detection of Surface Cracks in Metals Using Microwave and Millimeter-Wave Nondestructive Testing Techniques—A Review

“…Open-resonators employ inefficient EM radiating elements designed to concentrate the field in the proximity of the main radiating structure to increase the sensitivity and resolution [67], [68], [69], [70], [71], [72], [73], [74], [75], [76], [77], [78], [79], [80], [81], [82]. These methods were successfully demonstrated to detect 8-and 2-µm-wide fatigue cracks in steel in 1973 [67] and 1975 [68].…”

Detection of Reinforced Concrete Blocks Using Two-Port Microwave CSRR Sensor

“…This is due to the dramatic advancement in electronics from chips to system level as well as in the design of sensory elements. Moreover, design and development of sensors technology have played a major role in tackling a wide range of engineering and science problems, including medical diagnostics [1]- [2] and biosensing applications [3]- [5], defects in metallic objects, for example in aircraft fuselage [6]- [9] and structural materials [10]- [12], among others. Concrete blocks are considered artificial man-made stone type mass products and are very essential building units in engineering construction, for instance, buildings, bridges, and roads.…”

“…We highlight here that some of the earlier introduced sensing modalities were either large in size and often limited in their resolution. It is worth noting here that earlier studies have focused on development of radio-frequency/microwave sensors in order to detect cracks within metallic surfaces and subsurfaces [6]- [9]. Due to the nature of metallic surfaces and materials, high reflectivity signature is expected from such surfaces and thus detection of small abnormalities in metallic surfaces is quite straightforward and more noticeable.…”

A novel characterization method for water trees based on the transmission characteristics of complementary split ring resonators

“…The complementary split ring resonator (CSRR) can be used in the detection of biomolecules [18], metal cracks [19, 20], liquid concentration [21] and material defects [22] because of high sensitivity. The fabrication of the CSRR sensor is simple, and the cost is low.…”