LTCC-based broadband double-channel NMR coil with a split-spiral geometry

In the field of nuclear magnetic resonance (NMR), planar spiral detector coils have been exploited for their ease of fabrication with a high tolerance for accommodating flat samples and for the ability to be integrated with microfluidic systems. Additionally, recent studies demonstrated the feasibility of designing such micro planar spirals for broadband operation ^1,2 . Here we explore a novel embodiment of the planar spiral with a third contact added at an intermediary position of the spiral track, which acts as a double-channel NMR detector. The spiral geometry was optimized through simulation so that the inner loop and the full loop correspond to two frequency bands of interest. With the combined microfluidic and NMR devices fabricated for the first time in low-temperature cofired ceramic (LTCC) technology, we demonstrate untuned broadband operation by presenting 1D NMR spectra of 4 isotopes from 125MHz to 500MHz, as well as 2D ¹ H ^-13 C HSQC measurements. The design is easy to use and shows high robustness, demonstrating potential for NMR studies of flow systems with multiple nuclei.