Application of low-field nuclear magnetic resonance technology in multinuclide measurements and equipment development

Nuclear Magnetic Resonance (NMR) technology plays a key role in many fields such as medical imaging, chemical analysis and the petroleum industry. In chemical analysis and industrial testing, the ability to measure multiple nuclides quickly and accurately is essential for productivity and quality control. Especially in key areas such as petrochemicals, materials science and environmental monitoring, there is a growing demand for equipment that can measure multiple nuclides simultaneously. However, conventional high-field NMR devices are bulky and costly, limiting their widespread use in specific application scenarios. To address these challenges, a low-field NMR-based multinuclide measurement instrument has been successfully developed in this study, which is capable of accurately measuring four nuclides, namely hydrogen (H), sodium (Na), lithium (Li), and fluorine (F), in low-field environments, and is highly integrated and suitable for a wide range of practical applications such as laboratories, on-site inspections, and industrial production lines, and supports automated data acquisition, analysis, and remote monitoring. It supports automated data acquisition, analysis and remote monitoring.

In the field of petroleum energy and civil construction materials, low-field NMR technology equipment can quickly and accurately measure and characterise the hydrogen signal, which is widely used in the structural analysis and water content determination of porous media materials, especially in pore permeability saturation testing, which supports the optimisation of the performance of petroleum extraction and civil construction materials by detecting the pore structure and permeability of the materials ^[1][2]. In the field of oil drilling fluids, accurate measurement of sodium (Na) ion concentration is essential to ensure drilling fluid performance. This method utilises low-field NMR technology for the non-destructive detection of Na ions in drilling fluids to safeguard the stability and efficiency of drilling fluids. In addition, during the optimisation of cement formulations, the device is able to accurately determine the change in concentration of Na ions in seawater-configured cementitious materials, thereby improving the strength and durability of the cement ^[3][4][5][6]. For lithium (Li), a key component in battery materials, the device is able to effectively detect lithium ion signals under low-field conditions, supporting battery R&D and materials science research to ensure continued improvement in battery performance and lifetime ^[7]. Fluoride (F) content is also important in the toothpaste, pharmaceutical and materials industries, and the device can quickly determine fluoride content to help optimise product formulations and ensure product quality and safety.

The electronic spectrometer system uses multiple independent RF transmitter channels, each capable of transmitting RF pulse signals with different frequencies, amplitudes or phases to suit different sample characteristics and measurement needs. The system integrates MRF (Magnetic Resonance Fingerprinting) technology and intelligent multi-classification algorithms into the host computer, which automatically captures the sample's magnetic resonance signal patterns, such as T1 and T2 relaxation times, and applies them to different field strengths and pulse sequences. With the multi-classification algorithm, the system is able to recognise and differentiate between different signal patterns, each representing a group of samples with similar properties.