Novel applications of magnetic materials and technologies for medicine

Abstract

We analyze the applications of the magnetocaloric effect (MCE) achieved with advanced magnetic materials and technologies. New results such as the use of MCE-based composite material for ‘smart’ coating of implants, which allows for a controlled release of drugs over time. The material is comprised of two layers: the one manifesting a large MCE and the other made of a temperature-responsive polymer containing the drug. The latter is released by the polymer if the temperature induced by magnetic field (due to MCE) is changed. The polymer undergoes sharp phase transition in response to the slight temperature drop of ∼1–3 °C (down to 34–36 °C in the body). Local cooling is achieved with FeRh alloy, one of the most perspective MCE materials with the first order phase transition. It is critically important to take into account several peculiarities of phase transition and MCE behavior in these series of alloys. Recent studies on high-purity samples showed an ‘irreversible’ effect of MCE indicating that the temperature of FeRh does not return to its initial value after the full cycle of the magnetic field during dynamic MCE measurements. A theoretical explanation based on ab initio calculations has been provided. Magnetic hyperthermia in oncology is rapidly developing therapeutic modality. Recent experiments have shown that Mn-Zn ferrite emerges as a cost-effective material for this method compared with currently used magnetite nanoparticles. We present our achievements on magnetically guided capsule endoscopy. The advances in magnetically guided capsule endoscopy are also discussed. We provide the experimental setup for the computer-controlled system of magnetic field sources that create necessary forces to control the position of the capsule in five degrees of freedom in a given area. The system has the feedback on the position and is designed to monitor the endoscopic capsule during gastrointestinal tract examination.