Measuring movement and location in enclosed spaces using 3-axis anisotropic magneto resistive sensor array

Understanding the physiology of body systems through in vivo distance and positional measurement in narrow enclosed spaces presents several major challenges. A technique using a 3-axis anisotropic magneto resistive (AMR) sensor array is reported which has been developed to provide continuous real-time monitoring of the position of the gastro-oesophageal squamo-columnar junction (SCJ) for the study of the pathology of the upper gastrointestinal (GI) tract. A technical review is provided of the AMR sensor array for the measurement of mm distances to provide positional information in vivo. The device is used to measure distance along a string of sensors relative to a small magnet that is endoscopically clipped on to the SCJ. The probe consists of an array of 32 sensors mounted on a flexible printed circuit board within a silicone tube and provides a total measurement distance of 217 mm.