Magnet-Displacement Sensor Using Magneto-Inductive Elements for Sensing Eyelid Movement

We previously constructed an accurate displacement sensor for detection of eyelid movement, using an amorphous magnetic core multivibrator. Improvements in eyelid motion sensors are necessary to achieve independence of the magnetization direction of the cores as well as a broadened visual field. We constructed a second displacement sensor for detection of eyelid movement, this time using amorphous wire magneto-inductive (MI) elements. The elements were formed from tension-annealed zero-magnetostriction amorphous wires. The MI effect and the symmetrical MI characteristics of the elements were used to form thin sensor heads without coils. Inductances change independently of the magnet magnetization directions.