Multicoils-based inductive links dedicated to power up implantable medical devices: Modeling, design and experimental results

We present in this paper a new topology of inductively-coupled links based on a monolithic multi-coils receiver. A model is built to characterize the proposed structure using Matlab and is verified employing simulation tools under ADS electromagnetic environment. This topology accounts for the losses associated with the receiver micro-coil including substrate and oxide layers. The geometry of micro-coils significantly desensitizes the link to both angular and side misalignments. A custom fabrication process using 1 micron metal thickness is also presented by which two sets of micro-coils varying in the number of coils are realized. The first set possesses one coil 4 mm of diameter and represents a power efficiency close to 4% while the second set possesses multi-coils with an efficiency of 18%. The resulting optimized link can deliver up to 50 mW of power to power up an implantable device either sensor or stimulator. The experimental results for the prototypes are remarkably in agreement with those obtained from simulated models and circuits.