Improving the SNR of UMR sensor using LC resonator

Abstract

Single-sided or unilateral magnetic resonance (UMR) technology has various benefits, such as an open structure, low cost, portability, and nondestructive measurement, in contrast to the conventional closed magnet structure. UMR is widely used in material analysis, well logging, and biomedicine. However, its development is constrained by its poor signal-to-noise ratio (SNR). To enhance the SNR of UMR sensor, a surface coil of LC resonator is added on the Radio Frequency (RF) coil. First, a method of calculating the current in the RF coil including LC resonator is derived. Next, the equivalent AC resistance of the coil is calculated using the partial-element equivalent-circuit (PEEC) method. Finally, the SNR of a UMR sensor incorporating LC resonator is analyzed, and its sensitivity map is provided. Experimental comparisons are made between the UMR sensor with and without a LC resonator. Results show that the SNR of the UMR can be enhanced by up to three times after the LC resonator is loaded. The SNR improves within 30 mm of the coil surface, and this beneficial effect steadily diminishes as the distance increases. This study offers a useful method for improving the signal of UMR sensors.