MEMS NUCLEAR MAGNETIC RESONANCE MICROCOIL

Abstract

NMR is one of the important analytic tools which is used to obtain certain information such as metabolic concentrations in neural or muscular tissues. In some other important applications such as proton decoupling, it is necessary to design NMR transmitters/receivers capable of operating at multiple frequencies, while maintaining a good performance at each frequency. In this work, a new nuclear magnetic resonance (NMR) receiver microcoil based on MEMS technology is proposed. The designed structure uses MEMS microswitches with low contact resistance and NMR-based actuation mechanism. The proposed device can detect carbon (13C), proton (1H), and phosphorus (31p) nucleus with larmor frequencies of 96.36[Formula: see text]MHz, 383[Formula: see text]MHz, and 155.11[Formula: see text]MHz at 9 T magnetic field, respectively. The designed microcoil achieves three important goals: (1) Getting high SNR, high Q and high filling factor which are key parameters in NMR performance, by changing number of turns. (2) Turning into the array of microcoils to obtain better SNR. (3) Turning into two or three microcoils inside of each other for simultaneous detection. The MEMS microswitch in this paper uses static magnetic field of the NMR for its operation ([Formula: see text]T) which simplifies the switch mechanism. This switch is small (150[Formula: see text][Formula: see text]m[Formula: see text][Formula: see text][Formula: see text]50[Formula: see text][Formula: see text]m[Formula: see text][Formula: see text][Formula: see text]6[Formula: see text][Formula: see text]m), scattering parameters of 43.2[Formula: see text]db isolation and 0.0059 insertion loss and maximum displacement of 2.03[Formula: see text][Formula: see text]m due to the magnetostatic actuation. In this work, the models and investigations are conducted using finite element simulations in COMSOL Multiphysics. The switch scattering parameters are obtained by HFSS 12.0.