| Description |
Inherent in the nature of medical implant designs is the need to minimize their size and subsequent impact to their environment of use. Recently, many of the mechanisms used in implants have been constructed on the micro and even nano scales; however, powering these devices still remains a challenge. One of the more elegant solutions to this issue would be to construct a microscale wireless power receiver (or transducer) to deliver the needed power. This work serves to compare the viability of two transducer designs as candidates for their use as such a receiver. In particular the designs both use alternating magnetic fields as the power transmission medium and mechanically couple the magnetic and electric domains. The first design is a longitudinal (extension) mode magnetoelectric laminate comprised of magnetostrictive and piezoelectric layers. The second design is a symmetrically built mechano-magneto-electric transducer consisting of a piezoelectric bimorph with a permanent magnet mounted at its tip. A lumped parameter model was developed for the bending design while an existing model of the longitudinal design was augmented so that the power output of each device could be predicted and compared. Additionally, these models were experimentally validated. A linear numerical optimization was then performed using the models. The optimization was constrained at 2 mm3 maximum size as well as by IEEE and ICNIRP field restrictions to reflect the requirements of a medical implant. iv The results of the optimization showed that a magnetoelectric laminate made of Metglas and PZT layers delivered more power than that of a symmetric mechano-magnetoelectric transducer made of Brass, PZT, and Neodymium. Under IEEE field restrictions this amounted to ~40 mW of power delivery compared to ~4 mW. Under the ICNIRP restrictions, the corresponding power outputs are ~60 μW and ~26 μW respectively. These results indicate that a magnetoelectric laminate, particularly under IEEE conditions, is the more feasible of the two designs for powering microscale implants and efforts should be made to develop such a transducer. |
