Configuring magnetoresistive sensor array for head-sized magnetic particle imaging

Abstract

Magnetoresistive (MR) sensors offer a solution to enable unidirectional detection of sub-pT signal. Magnetic particle imaging (MPI) can benefit from this high sensitivity to challenge its operability under low excitation fields. Here, we built a prototype of brain MPI scanner by using MR sensor array to directly map stray fields of the magnetized magnetic nanoparticles. The array was a 13×13 matrix with 15 mm sensor pitch and installed at 100 mm apart from excitation coil with 200 mm in diameter. We magnetically compensated both the drive field and geomagnetism to position MR sensor at field-free environment. Preliminarily, we were able to detect a 37 mg_Fe ferrofluid sample at 50 mm apart from the array under field amplitudes up to 100 ?T/?₀ at 10 kHz. The resulting noise level appears independent to the applied field, which becomes an advantage to further implement higher drive fields within magnetostimulation safety limits.