A magnetic tracking system based on highly sensitive integrated hall sensors

A tracking system with five degrees of freedom based on a 2D-array of 16 Hall sensors and a permanent magnet is presented in this paper. The sensitivity of the Hall sensors is increased by integrated micro(-) and external macro(-)flux(-)concentrators. Detection distance larger than 20 cm (during one hour without calibration) is achieved using a magnet of 0.2 cm(3). This corresponds to a resolution of the sensors of 0.05 muT(rms). The position and orientation of the marker is displayed in real time at least 20 times per second. The sensing system is small enough to be hand-held and can be used in a normal environment. This presented tracking system has been successfully applied to follow a small swallowed magnet through the entire human digestive tube. This approach is extremely promising as a new non-invasive diagnostic technique in gastro-enterology.