Energy-Autonomous Wireless Implantable Sensors Powered by Piezoelectric Transducers with Magnetic Plucking

Wireless sensors have been increasingly used in various industrial applications especially with the proliferation of the Internet of Things. In this work, an energy-autonomous solution for wireless implantable sensors is developed and illustrated, allowing medical implants to be self-sustained within the human body over long terms. This solution consists of a piezoelectric transducer with a tip magnet mounted on an implantable sensor and a wearable rotating magnetic array which can be driven either by human motion or motors. A complete theoretical model has been established in this work to study the electromechanical dynamics and the wireless power transfer capability. Different magnetic array configurations are explored to increase the power transfer distance and output level. A prototype was fabricated and tested in laboratory conditions along with a power management and control solution to verify the concept and the design. The wireless power transfer solution delivers around 0.28 mW power using a 26.5x1.5x0.3 mm piezoelectric beam, over a large transmission distance 18 mm, demonstrating its capability in implementing energy-autonomous wireless implantable sensors.