Gradient-Field Frequency Encoding for 1D Localization of Magneto-Mechanical Resonators

Abstract

Magneto-mechanical resonators (MMRs) have emerged as promising passive sensors for wireless localization and remote inductive sensing in industrial and medical environments. However, fundamental limits on achievable localization accuracy using the spatial sensitivity profiles of receive coils remain a key challenge. In this work, we demonstrate that an MMR - comprising two permanent magnets in an anti-parallel arrangement - exhibits a measurable shift in its mechanical resonance frequency in response to an externally applied magnetic field, a property we exploit for spatial encoding. We derive and experimentally validate a method that maps frequency shifts of 1D positions within a known magnetic gradient field, demonstrating accurate localization along a linear trajectory. This gradient-field frequency encoding approach constitutes a conceptually distinct alternative to conventional sensitivity encoding with receiver coil arrays, with the potential to simplify hardware requirements while improving localization accuracy.