Miniaturization and Optimization of NMR Shimsets Allow Efficient Field Shimming

We present a finite element method (FEM)-based framework for the joint optimization of nuclear magnetic resonance (NMR) cells, encompassing both the radio frequency (RF) coil and integrated shim systems. This approach enables systematic design with respect to sensitivity, RF isolation, and magnetic field homogeneity, ensuring efficient operation under demanding high-field conditions. As a proof of concept, we demonstrate a four-channel parallel NMR spectroscopy probe, where each channel incorporates a stripline-based RF detector confined by ground planes for intrinsic shielding and reduced interchannel coupling. Localized shimsets (x, y, z, and z²) are codesigned with the RF coils to achieve high field homogeneity within each sample volume. At a proton Larmor frequency of 650 MHz (15.2 T), the optimized detectors exhibit a quality factor (Q) of 53 and residual interchannel coupling between -25 dB and -80 dB. The integrated shim systems achieve line widths as low as 2.8 Hz and resolve selected J-couplings while operating with currents in the range of -3 mA to 16 mA. These results highlight the potential of FEM-guided NMR cell optimization for enabling advanced multichannel probe architectures.