A low-power high-sensitivity single-chip receiver for NMR microscopy.

Area of Science:

• Electrical Engineering
• Biomedical Engineering
• Materials Science

Background:

• Nuclear Magnetic Resonance (NMR) microscopy requires sensitive detection coils and integrated receivers for high-resolution imaging.
• Previous NMR microscopy systems faced limitations in achievable image signal-to-noise ratio (SNR) and image artifacts due to coil sensitivity profiles.

Purpose of the Study:

• To present a fully-integrated receiver for NMR microscopy applications fabricated in 0.13μm CMOS technology.
• To investigate the relationship between detection coil spin sensitivity and image SNR in NMR microscopy.
• To address and correct image artifacts caused by inhomogeneous sensitivity profiles of planar detection coils.

Main Methods:

• Co-integration of a 10-turn planar detection coil and a quadrature, low-Intermediate Frequency (IF) downconversion receiver on a single chip.
• Operation from a single 1.5V supply with low power dissipation (18mW).
• Derivation and validation of analytical expressions for image SNR and sensitivity correction in Computed Tomography Imaging (CTI) MR experiments.

Main Results:

• Measured time-domain spin sensitivity of 3×10^13 (1)H spins/Hz at 7 Tesla.
• Achieved isotropic resolutions of 9.6μm and 5μm with single-shot SNRs of 37 and 15, respectively.
• Successful acquisition of sensitivity-corrected images in a 7T spectroscopy magnet within reasonable imaging times (4.4h and 24h).

Conclusions:

• The developed integrated receiver chip significantly improves spin sensitivity for NMR microscopy.
• The derived analytical expressions provide a framework for optimizing NMR microscopy imaging parameters and correcting artifacts.
• This work demonstrates the potential of integrated CMOS technology for advancing high-resolution NMR microscopy applications.