MEMS Components for NMR Atomic Sensors

This paper introduces a batch fabrication method to manufacture micro-electromechanical system (MEMS) components for nuclear magnetic resonance (NMR) atomic sensors, such as NMR gyroscope (NMRG) and NMR magnetometer (NMRM). The components presented are: 1) micro-coils generating the magnetic field with the magnetic field homogeneity of H = 354 ppm; 2) spherical micro-fabricated atomic cells confining alkali metal and noble gases; 3) micro-heaters keeping the alkali metal in a vapor state while minimizing residual magnetic fields; and 4) origamilike silicon structures with integrated optical reflectors preserving 90.9% of the light polarization. The introduced design utilized a glassblowing process, origamilike folding, and a more traditional MEMS fabrication. We presented an analytical model of imperfections, including errors associated with microfabrication of MEMS components. In light of the developed error model, phenomenological dynamic model describing NMR sensors, and experimental evaluation of components, we predicted the effect of errors on performance of NMRG and NMRM. We concluded that with a realistic design, a 5-mrad angular misalignment between coils and folded mirrors, and a 100-μm linear misalignment between folded coils, it would be feasible to achieve an NMRG with ARW 0.1 deg/rt-hr and an NMRM with sensitivity on the order of 10 fT/rt-Hz.