Wireless 3D Surgical Navigation and Tracking System With 100μm Accuracy Using Magnetic-Field Gradient-Based Localization

Abstract

This paper describes a high-resolution 3D navigation and tracking system using magnetic field gradients, that can replace X-Ray fluoroscopy in highprecision surgeries. Monotonically varying magnetic fields in X, Y and Z directions are created in the field-of-view (FOV) to produce magnetic field gradients, which encode each spatial point uniquely. Highly miniaturized, wireless and battery-less devices, capable of measuring their local magnetic field, are designed to sense the gradient field. One such device can be attached to an implant inside the body and another to a surgical tool, such that both can simultaneously measure and communicate the magnetic field at their respective locations to an external receiver. The relative location of the two devices on a real-time display can enable precise surgical navigation without using X-Rays. A prototype device is designed consisting of a micro-chip fabricated in 65nm CMOS technology, a 3D magnetic sensor and an inductor-coil. Planar electromagnetic coils are designed for creating the 3D magnetic field gradients in a 20x20x10cm 3 of scalable FOV. Unambiguous and orientation-independent spatial encoding is achieved by: (i) using the gradient in the total field magnitude instead of only the Z-component; and (ii) using a combination of the gradient fields to correct for the nonlinearity and non-monotonicity in X and Y gradients. The resultant X and Y FOV yield ≥90% utilization of their respective coil-span. The system is tested in vitro to demonstrate a localization accuracy of <100µm in 3D, the highest reported to the best of our knowledge.

A Low-Cost, Open-Source-based Optical Surgical Navigation System Using Stereoscopic Vision

“…To address this, researchers have explored various techniques for surgical navigation, including mechanical tracking, electromagnetic tracking, ultrasound tracking, and more. In particular, Sharma et al proposed adopting electromagnetic tracking for performing implant surgery utilizing monotonic variations in magnetic fields along the X, Y, and Z axes (Sharma et al (2021)). By attaching microchips to an implant within the body and another to a surgical tool, the devices concurrently measured and relayed magnetic field information from their respective locations to an external receiver.…”

Integrated Sensors for Soft Medical Robotics

“…Furthermore, the size of permanent magnets used needs to be large enough to emit a sufficient magnetic field for a centimeterscale precision captured by the HESs, thus limiting the miniaturization and multiplexing capability of ingestible devices. Inspired by the magnetic resonance imaging (MRI) technology, Sharma et al [135,146] developed a novel tracking system that internally placed a 3D HES device inside the WCE to avoid the risk of magnetic interferences, as well as improving the spatial resolution and FOV. The magnetic source was generated by a set of wearable 3D electromagnets that emit monotonical magnetic field gradients in each orthogonal axis, where each spatial point in the FOV can be subsequently encoded by distinct field density magnitudes (Figure 7c-e).…”

Gradiometer-Based Magnetic Localization for Medical Tools

“…Promising advances have been made in medical tool localization with the use of Hall-effect sensors [6], [7]. Sharma et al developed a localization system in which the sensor is attached to a non-magnetic medical device [8]. By applying fast current bursts to the individual coils, they were able to determine the position of the sensor with high accuracy.…”