Disclosed is an implantable system that comprises a magnetoelectric (ME) antenna, a radio frequency rectifier, and a transmitter. The ME antenna may be characterized by a resonance frequency that changes according to an ambient magnetic field strength. The radio frequency rectifier may be configured to convert radio frequency energy, received by the ME antenna, into a direct current voltage, and to direct the direct current voltage to a storage capacitor. The transmitter may be configured to apply a transmission signal to the ME antenna. A transceiver may communicate with one or more of the implantable systems, to provide radio frequency energy to the implantable devices for energy harvesting, and to receive transmitted information from the implantable systems. The implantable system may be disposed within a brain to detect neuronal activity, by detecting small magnetic fields generated by such neuronal activity.
