CMOS 3D Hall probe for magnetic field measurement in MRI scanner

This paper presents a 3D Hall probe integrated in a 0.35μm CMOS technology and dedicated to the measurement of the magnetic field gradients in a MRI scanner. It features a 3D Hall device and three instrumentation chains which suppress the MRI main magnetic field and amplify dedicated magnetic field gradients. The unique relationship between the space coordinates in the scanner bore and the magnetic field gradients allows determining accurately the location of the Hall probe inside the bore. First experimental results show that the proposed 3D Hall probe could be used for a MRI tracking system with a sub-millimeter spatial resolution. It is a first step towards the instrumentation of MRI-compatible minimally-invasive surgical tools.