Near-Field Inductive-Coupling Link to Power a Three-Dimensional Millimeter-Size Antenna for Brain Implantable Medical Devices.

Abstract

Near-field inductive-coupling link can establish a reliable power source to a batteryless implantable medical device based on Faraday's law of induction. In this paper, the design, modeling, and experimental verification of an inductive-coupling link between an off-body loop antenna and a 0.9 three-dimensional (3-D) bowtie brain implantable antenna is presented. To ensure reliability of the design, the implantable antenna is embedded in the cerebral spinal fluid of a realistic human head model. Exposure, temperature, and propagation simulations of the near electromagnetic fields in a frequency-dispersive head model were carried out to comply with the IEEE safety standards. Concertedly, a fabrication process for the implantable antenna is proposed, which can be extended to devise and miniaturize different 3-D geometric shapes. The performance of the proposed inductive link was tested in a biological environment; in vitro measurements of the fabricated prototypes were carried in a pig's head and piglet. The measurements of the link gain demonstrated in the pig's head and in piglet. The in vitro measurement results showed that the proposed 3-D implantable antenna is suitable for integration with a miniaturized batteryless brain implantable medical device (BIMD).