_Appl. Sci._**2015**, \(5\), 1412-1430; doi:10.3390/app5041412  
_applied sciences_  
**ISSN 2076-3417**  
www.mdpi.com/journal/applsci  
Enhancement of Spatial Resolution Using a Metamaterial Sensor in Nondestructive Evaluation \({}^{\dagger}\)  
**[PERSON] \({}^{1,\star}\), [PERSON] \({}^{2,\star}\), [PERSON] \({}^{1,3}\), [PERSON] \({}^{1}\) and [PERSON] \({}^{4}\)**  
\({}^{1}\) Nondestructive Testing Department, National Institute of R&D for Technical Physics,  
Iasi 700050, Romania; E-Mails: [EMAIL_ADDRESS] (R.S.); [EMAIL_ADDRESS] (N.I.)  
\({}^{2}\) CRISMAT Laboratory, Ecole Nationale Superieure d'Ingenieurs de Caen, Universite de Caen Basse Normandie, 6 Blvd Marechal Juin, Caen 14050, France  
\({}^{3}\) Faculty of Physics, University Al.I. Cuza, 11 Carol I Blvd, Iasi 700506, Romania  
\({}^{4}\) Faculty of Electrical Engineering, University of Zilina, Univerzitna 1,  
Zilina 010 26, Slovakia; E-Mail: [EMAIL_ADDRESS]  
\({}^{\dagger}\) This paper is an extended version of paper published in the 6 th International Conference on Emerging Technologies in Non-destructive Testing, ETNDT6 held in Brussels, 27-29 May 2015.  
\({}^{\star}\) Authors to whom correspondence should be addressed: E-Mails: [EMAIL_ADDRESS] (A.S.);  
[EMAIL_ADDRESS] (A.B.); Tel.: +40-232-430680 (A.S.); +33-231-452610 (A.B.);  
Fax: +40-232-231132 (A.S.); +33-231-951600 (A.B.).  
Academic Editor: [PERSON]  
_Received: 17 September 2015 / Accepted: 11 November 2015 / Published: 27 November 2015_  
**Abstract:** The current stage of non-destructive evaluation techniques imposes the development of new electromagnetic methods that are based on high spatial resolution and increased sensitivity. Printed circuit boards, integrated circuit boards, composite materials with polymeric matrix containing conductive fibers, as well as some types of biosensors are devices of interest in using such evaluation methods. In order to achieve high performance, the work frequencies must be either radiofrequencies or microwaves. At these frequencies, at the dielectric/conductor interface, plasmon polaritons can appear, propagating between conductive regions as evanescent waves. Detection of these waves, containing required information, can be done using sensors with metamaterial lenses. We propose in this paper the enhancement of the spatial resolution using electromagnetic methods, which can be accomplished in this case using evanescent waves that appear in the current study in slits of materials such as the spaces between carbon fibers in Carbon Fibers Reinforced Plastics or in materials of interest in the nondestructive evaluation field with industrial applications, where microscopic cracks are present. We propose herein a unique design of the metamaterials for use in nondestructive evaluation based on Conical Swiss Rolls configurations, which assure the robust concentration/focusing of the incident electromagnetic waves (practically impossible to be focused using classical materials), as well as the robust manipulation of evanescent waves. Applying this testing method, spatial resolution of approximately \(\lambda\)/2000 can be achieved. This testing method can be successfully applied in a variety of applications of paramount importance such as defect/damage detection in materials used in a variety of industrial applications, such as automotive and aviation technologies.  
**Keywords:** nondestructive evaluation; metamaterials lens; metallic strip gratings; fiber reinforced plastic composites; evanescent waves