Characteristics of a bending beam force sensor array element

Results are reported for a low-compliance force sensor which is based on the change of magnetic properties of FeSiB amorphous ribbon when stressed and compressed. The signal is sensed via a magnetostrictive delay line, which makes it possible for arrays of sensors to be formed very simply. The sensor has a balanced structure consisting of two amorphous ribbons mounted on opposite faces of a bending beam and two conductors carrying identical pulsed exciting currents, arranged symmetrically about a point on the delay line, the conductors being orthogonal to it. When the sensor is loaded, one ribbon is under tension and the other one compressed, so that the passive magnetic circuit linking exciting currents and the delay line becomes unbalanced, to a degree depending on the tension and compression, and a nonzero output pulse is produced. Two small field magnets could be close to the sensing point and the receiving coil of the delay line, in order to maximize the detected signal. Input and output of the sensor are the force on the bending beam and the peak value of the detected signal