Designing and building a low-cost portable FT-NMR spectrometer in 2019: A modern challenge

Abstract

Abstract High-field Fourier-Transform Nuclear Magnetic Resonance (FT-NMR) spectroscopy is a high performance spectroscopic technique that is essential in many analytical fields. The non-destructive nature of NMR makes it a preferred means of analyzing chemical and biological environments. Compact benchtop NMR spectrometers are low-cost alternatives to conventional high-field and high-resolution spectrometers. A research laboratory may want to develop its own compact FT-NMR spectrometer (home-built benchtop NMR) with a very low financial cost (∼10 k€). But why? First of all, to use it punctually as an additional channel (nucleus X) to a high-resolution spectrometer, and also to be able to couple it with complementary physics instruments such as an optical microscope to study spin diffusion in semiconductors, for instance. In addition, a home-built NMR spectrometer can be used with a low-field permanent magnet for the quantification of species that does not necessarily require high-resolution, avoiding the need for weekly and expensive cryogenic services. Outside the research laboratory, this portable NMR can be used for the in situ analysis of outdoor natural environments. Finally, this compact spectrometer is naturally dedicated to the teaching of NMR technique and is open to the study of the basic electronic functions that constitute an NMR spectrometer. The main question then arises: how to build a robust Home-Built” NMR? In this article, we describe the realization of an NMR instrument based on electronic components and boards (LNA, ADC, FPGA, ARM, DDS…) easily commercially available, allowing one to obtain a benchtop NMR instrument presenting both a high acquisition dynamics and a good signal-to-noise ratio.