A Self-Powered Magneto-Acoustic Tracking Transducer

Abstract

Acoustic telemetry is widely used for many tracking applications. Objects or subjects are tracked by attaching an acoustic transmitter onto them or having them wear them. The acoustic signal is then detected by different microphones to determine the location of the tagged target. The size and the weight of the tag determine the size of the target that can be tracked. In the case of small-sized tags, about 80% of the volume is consumed by the battery and electronics, while less than 20% by the actual acoustic transducer. Here, we propose a self-powered acoustic tracking transducer that utilizes a magnetic frequency up-converter that directly converts the low-frequency motions of a target to a high-frequency acoustic signal. The intensity of the output signal is enhanced by realizing a bistable cantilever design by local crystallization of an amorphous metal transducer. A micro device has been realized with dimensions of 8×13×38 mm3 and a weight of 1.3 g. The measurement results show that the transducer up-converts a low-frequency of 7 Hz to 15 kHz, directly and without the need for an external power source.