Magneto-oscillatory localization for small-scale robots

TL;DR

The paper introduces SMOL, a novel magneto-oscillatory localization technique enabling millimeter-scale robots to achieve full six degrees of freedom in deep tissues, overcoming previous limitations of static magnetic methods.

Contribution

SMOL uses oscillation of a resonant cantilever with a magnetic dipole to break symmetry, allowing high-precision 6-DOF localization in biological tissues.

Findings

Achieves sub-millimeter accuracy over 12 cm distance

Supports quasi-continuous 200 Hz refresh rate

Demonstrated in real-time surgical robot control

Abstract

Magnetism is widely used for the wireless localization and actuation of robots and devices for medical procedures. However, current static magnetic localization methods suffer from large required magnets and are limited to only five degrees of freedom due to a fundamental constraint of the rotational symmetry around the magnetic axis. We present the small-scale magneto-oscillatory localization (SMOL) method, which is capable of wirelessly localizing a millimeter-scale tracker with full six degrees of freedom in deep biological tissues. The SMOL device uses the temporal oscillation of a mechanically resonant cantilever with a magnetic dipole to break the rotational symmetry, and exploits the frequency-response to achieve a high signal-to-noise ratio with sub-millimeter accuracy over a large distance of up to 12 centimeters and quasi-continuous refresh rates up to 200 Hz. Integration into real-time closed-loop controlled robots and minimally-invasive surgical tools are demonstrated to reveal the vast potential of the SMOL method.