Micro Blood Pressure Energy Harvester for Intracardiac Pacemaker

This paper presents the design, fabrication, and tests of a microspiral-shaped piezoelectric energy harvester and its associated microfabricated packaging that collects energy from ordinary blood pressure variations in the cardiac environment. This device could become a life-lasting, miniaturized energy source for active implantable medical devices such as leadless pacemakers. We present the concept and tested prototypes of 10 μm thin and ultra-flexible electrodeposited microbellows (6mm diameter, 21mm³ volume) as a new type of implant packaging. It enables direct blood pressure harvesting and permits a high efficiency of energy transfer to a transducer operating in quasi-static mode and hence adaptable and unaffected by frequent heartbeat frequency changes. Spiral-shaped piezoelectric transducers are introduced for their flexibility and large incoming mechanical energy. Non-trivial optimal electrodes placement and best spiral design parameters are studied and discussed. Three types of spiral prototypes (11mm³ volume each) with doubled-sided microstructured electrode patterns are presented and characterized. A power of 3 μJ/cm³/heartbeat and a transduction efficiency of 5.7×10^-3 have been obtained for the best designs at 1.5Hz and we predict that twice as much could be obtained using similar design process and material. Through implementing smart adapted electronic circuits, a potential additional tenfold increase in power output could be achieved, which would be sufficient to power a leadless pacemaker.