A self-biased magnetoelectric wireless power transfer receiver targeting biomedical implants

The use of magnetoelectric (ME) devices in the field of wireless power transfer (WPT) is attractive due to their smaller size and lower operating frequencies compared to traditional coils. Their use may be particularly valuable to charge devices in space constrained applications, such as biomedical implants, where the power must also be transferred through lossy media. However, ME devices require a relatively large DC magnetic field bias for optimal performance. Supplying this DC bias with permanent magnets or electromagnets is impractical in many applications and may cause safety concerns in the case of biomedical devices. To solve this problem, this paper presents an approach for self-biased ME structures using the magnetization grading effect. We investigate the operation and experimentally characterize the voltage and power output of multi-layer self-biased ME laminates. We demonstrate devices made of Metglas, Ni, and PZT of 0.05 cm(3) in size that can generate similar to 250 mu W from an applied 100 mu T RMS AC field with no DC field bias. This size, power, and AC magnetic field combination makes these laminates attractive for powering biomedical implants.