A compact and mobile stray-field NMR sensor

Journal of Magnetic Resonance, vol. 369, pp. 107798

Abstract

In this paper, we introduce a compact, single-sided stray field sensor for NMR relaxometry applications. The sensor consists of four main components: the magnet, the RF coil, the spectrometer, and the translation stage. Our proposed magnet, an improved design of the Profile NMR-MOUSE, is designed for low weight, compactness, and magnetic field homogeneity, achieved through various shim strategies using a mixed genetic algorithm. The magnet comprises eight NdFeB blocks, generating a magnetic field of 0.424T within the sensitive region, positioned 12 mm above the magnet surface. For high spatial resolution measurements, we optimized the sensor performance by using a custom-designed rf coil, providing maximum sensitivity, lateral selectivity, and a dead time of less than 20µs. Moreover, we utilized 3D-printed structures to precisely align the sensitive slice within the object, using an experimental approach based on CPMG measurements. The presented setup achieved a spatial resolution of 50µm, with resolution changes proportional to acquisition time. We demonstrate the sensor's versatility and high resolution with measurements on materials such as cosmetics, elastomers, glue, and wood, verifying the good performance of our design, our alignment strategy, and the measuring scheme.

Authors 4

1. Belal M.K. Alnajjar

   University of Stuttgart

   Affiliation as printed

   Institute of Smart Sensors, University of Stuttgart, Stuttgart, Germany. Electronic address: belal.alnajjar@iis.uni-stuttgart.de

2. Jürgen Frick

   University of Stuttgart

   Affiliation as printed

   Materials Testing Institute, University of Stuttgart, Stuttgart, Germany

3. Bernhard Blümich Aachen Institut für Technische und Makromolekulare Chemie

   RWTH Aachen University

   Affiliation as printed

   Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Aachen, Germany

4. Jens Anders

   University of Stuttgart · Center for Integrated Quantum Science and Technology · Institut für Mikroelektronik Stuttgart

   Affiliation as printed

   Institute of Smart Sensors, University of Stuttgart, Stuttgart, Germany; Center for Integrated Quantum Science and Technology (IQ(ST),), Stuttgart, Germany; Institute for Microelectronics Stuttgart (IMS CHIPS), Stuttgart, Germany