On-Chip Nuclear Magnetic Resonance

Abstract

Nuclear magnetic resonance (NMR) is one of the prime modalities for probing molecular structure in the biomedical context and analyzing bulk material properties for quality control, food product analysis, and nondestructive testing. Conventional state-of-the-art NMR spectroscopy systems utilize bulky superconducting magnets, have a room-filling size, and cost millions of euros. Over the past decade, advances in permanent magnet technology have led to the availability of benchtop NMR spectrometers and even smaller NMR relaxometers for analyzing bulk material properties and performing immunoassays. With the availability of these smaller NMR magnets, NMR electronics have entered the focus of attention as a key component for miniaturized, portable NMR devices. Here, the on-chip NMR approach, in which all required electronics are realized on a single integrated circuit, allows for a realization in an ultra-small form factor and offers great promise for reducing the overall system cost. In this chapter, a comprehensive and self-contained overview of the on-chip NMR approach in the biomedical context will be given. After an introduction into the topic, the physical origin of the NMR signal will be discussed together with means of exciting and detecting it. This is followed by a review of conventional NMR electronics, including its key performance metrics. In the main part of this chapter, the NMR-on-a-chip approach is introduced, and its advantages and disadvantages are highlighted. Finally, the chapter is concluded with a summary and an outlook on the possibility of enhancing the achievable performance of the NMR-on-a-chip approach with on-chip dynamic nuclear polarization (DNP) capabilities.