Laser Fiber Optic Sensor for Human Biomagnetic Measurements

摘要

The human body produces magnetic fields due to electric current sources generated by the muscles, nerves and other organs. The organs which produce the magnetic fields of interest in biomagnetism are the heart and the brain which generate fields around the chest and the head, respectively. Biomagnetic research has provided significant contributions to the study of magnetic activities in the human body. The presently available diagnostic tool for such applications (e.g: neuromagnetic fields as low as 10 Tesla) is the superconducting quantum interference device (SQUID) magnetometer. However, the SQUID sensor requires cryogenic instrumentation, thereby limiting the conditions under which the magnetometer can be used and contributing to a much high system cost. In order to permit the evaluation of human biomagnetic fields under mission operating conditions, this program involved the development of a compact, sensitive, room-temperature biomagnetic sensor based on a laser- stimulated fiber optic interferometer with magnetostrictive field sensing elements. The overall goal of the Phase II research program was to demonstrate the performance of fiber optic-based magnetic sensors to be used in human magnetocardiography (MCC) and magnetoencephalography (MEG). The Phase II research effort constituted the investigation of the following technical objectives: extension of magnetostrictive/fiber interaction models; improvement of the fiber optic interferometer design; evaluation of methods to increase the magnetostriction-to-fiber strain transfer efficiency; interaction of hybrid micro-optoelectronic magnetometers; application of multiple laye: sensor arrays and gradiometer operation; acquisition of families of simulated biomagnetic test data and optimization of a proof-of-concept system.