Methods and devices including amorphous magnetic microwires are provided for biomedical energy transfer for diagnosis or therapy, to promote cellular growth, or to deliver pharmaceutical agents. Applications of the technology include in sensors, actuators, and therapeutic coatings, and for increasing the amount, directionality, or length of nerve growth. The technology also can be utilized for nerve regeneration, hyperthermic treatment of tumors, vascular theranostics, probing a nerve, stimulating a nerve, sensing a biological condition, catheterization, and micro-actuation.