A Novel Energy Harvesting Circuit for RF Surface Coils in the MRI System.

ABSTRACT

RF surface coils are commonly used as receivers in Magnetic Resonance Imaging (MRI) systems to acquire sensitive signals from the human body. These coils rely on cables for power and transferring information from the patient to the computer for processing. Higher image quality and faster scan times are possible by using an array of surface coils, and there is a constant need for high-density surface coil arrays. Each array element utilizes at least three cables and, increasing the number of elements in the array also increases the number of cables, making the cable bundle bulkier. This makes the placement of cables complicated for the operators and may cause patient harm when improperly positioned. Wireless technologies can eliminate cables, and this paper proposes a novel design for harvesting the ambient RF energy present during the transmit phase of the MRI system operation. After introducing the surface coil's building blocks, the importance of the decoupler as a mechanism for safety and image quality is detailed. The paper presents the analysis and design of an RF energy harvesting circuit that couples to the decoupler circuit. Its performance is tested both in simulation and the Philips Ingenia 3.0 T MRI system. The results show that the circuit successfully harvests energy, up to 1 W, during the MRI's transmit phase without any adverse effects on the decoupler or surface coil. To make energy harvesting (EH) beneficial, a new GaN -based FET switch that consumes low power is also proposed.