Development of a jaw-position measuring system using magneto-impedance (MI) sensor

An accurate linear position sensor was devised by applying magneto-impedance (MI) sensors for the vertical dimension measurements of dentures. A theoretical equation was generated to describe the distribution of magnetic flux density to the arrayed direction between a columnar magnet and arrayed MI sensors. Calculations made show that, in order to assure the linear relation between position and generated magnetic field, the distances between each measuring point should be as small as possible. Results indicate that when a ferrite magnet with 10 mm diameter and 1 mm thick is placed in 30 mm distance from the sensor board, the accuracy of the position was 0.1% in the full scale of 20 mm. The developed sensor gives position according to jaw movement.