PCB Coil Pairs for Small Magnetic Volumes

Here we describe a compact radiofrequency (RF) magnetic field generator designed to generate fields within millimeter-scale volumes. The device consists of printed multilayer circuit board (PCB) coils stacked in a paired parallel configuration. Compared to conventional solenoidal systems, this architecture significantly reduces device size, sample volume, and power requirements. We characterize the RF response of the system, including impedance and scattering parameters, and describe the behavior near ~330 kHz, which overlaps with frequencies common in magnetic nanoparticle heating, magnetic actuation, and other applications requiring localized fields. Electromagnetic modeling is used to evaluate magnetic field amplitude and spatial homogeneity (finding a maximum local deviation from the mean field of 5.5%). The mean B_z field across a 5 mm × 5 mm ROI centered between paired PCBs was 6.3 ± 0.1 mT/A (compared to 6.1 ± 1.0 mT/A measured experimentally). These results demonstrate operating parameters consistent with nanoparticle heating applications for PCB-based coil pairs.