A Novel Wireless Charging Technique for Low-Power Devices Based on Wiegand Transducer

During last decade biomedical devices have become more and more performing, covering an increasing number of usages. In particular, subcutaneous devices represent one of the most invasive yet innovative application; their battery management is one of the most challenging topics because, once implanted, they can be handled only through surgery, so wireless charge is the only way to feed subcutaneous systems with appreciable energy in a controlled manner. But differently from conventional consumer devices, in this scenario the energy delivered necessarily runs into human body and tissues, so the main challenge consists in maximizing the "energy delivered versus energy dissipated in tissues" ratio, in order to guarantee human safety first while also conveying an appreciable amount of energy to the implanted device. After analyzing the state-of-the-art of the principal techniques, this article proposes a novel architecture for low-power wireless charging, based on a Wiegand sensor used as a transducer in order to fulfill all the requirements from both electrical and medical points of view; such architecture is implemented inside an IC prototype in 0.35- $\mu \text{m}$ lithography that acts as an ultralow-power DC-DC buck converter and battery manager.