Compact, deadtime-free, stray-field NMR sensor

• Applicants: Professor Dr. Jens Anders; Dr. Jürgen Frick
• Subject Area: Physical Chemistry of Solids and Surfaces, Material Characterisation ; Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 450272390

Stray-field NMR is a technique for nondestructive materials testing in the laboratory. It is well established in the scientific community and industry. Primary applications are found in quality control and aging of polymers and related materials, including PE pipes, PVC flooring, car tires, asphalt pavements, human skin, and food products. These materials can, in many cases, be serviced with commercial laboratory-based technology from vendors such as Magritek and Bruker. However, the dead time of the current sensors is too long for useful materials analysis applied to e. g. bound water in building materials such as cement, glass- and carbon-fiber-reinforced polymer composites in windmill wings, and varnish on paintings and musical instruments. Moreover, emerging applications such as the analysis of tangible cultural heritage and outdoor measurements would greatly benefit from improvements concerning the equipment to function in remote locations and under adverse environmental conditions and the identification of relevant correlations between NMR relaxation/diffusion and application parameters. The main scientific goal of this project is to achieve a significant reduction of the dead time of compact stray-field NMR sensors from currently 70 µs to less than 20 µs at 10 mm depth of access. Moreover, we will investigate strategies for miniaturizing the spectrometer, sensor, and mechanical translation stage for depth profiling by shrinking each element and integrating them into a single device. Together with additional research on reducing the power consumption to allow for operation from a car battery, on including a sensor for the precise parallel alignment of the NMR device with the object, and significantly improving the ruggedness of the setup, e. g. by increasing its tolerance to electromagnetic interference, a research instrument will be investigated and prototyped that enables entirely new in-field applications of stray-field NMR. This includes nondestructive materials testing at production lines online, as well as applications in museums, heritage, and excavation sites outdoors. An interdisciplinary team of three PIs will ensure compatibility of the envisioned prototype with in situ and in-field requirements and validate it in laboratory tests and pilot studies.

• DFG Programme: New Instrumentation for Research