Magnetic Implantable Devices and Materials for the Brain

Understanding the brain's complexity and developing treatments for its disorders necessitates advanced neural technologies. Magnetic fields can deeply penetrate biological tissues-including bone and air-without significant attenuation, offering a compelling approach for wireless, bidirectional neural interfacing. This review explores the rapidly advancing field of magnetic implantable devices and materials designed for modulation and sensing of the brain. Key modulation strategies include: magnetoelectric (ME) materials that convert magnetic into electric fields for stimulation; magnetothermal (MT) effects, where heating of nanoparticles activates thermosensitive ion channels; and magnetomechanical (MM) approaches that use magnetic forces to gate mechanosensitive channels. Methods for magnetic-based detection encompass: implantable magnetoresistive probes for the reference-free measurement of weak local neural magnetic fields; magnetic resonance needles that enhance metabolic profiling; and magnetoelastic systems where external magnetic fields vibrate magnetic implants to sense biophysical and biochemical conditions. The breadth of these magnetic transduction mechanisms promises future technologies that provide less invasive and more precise methods for understanding and regulating brain function.