A sub-cc nonlinear piezoelectric energy harvester for powering leadless pacemakers

Abstract

A miniature nonlinear piezoelectric energy harvester is developed to power state of the art leadless cardiac pacemakers from cardiac motions. The energy harvester is integrated in the leadless pacemaker and is connected to the myocardium. The energy harvester converts myocardial motions to electricity to power leadless pacemakers. The energy is stored in a battery or supercapacitor and is used for pacing. The device is composed of a bimorph piezoelectric beam confined in a gray iron frame. The system is assembled at high temperature and operated at the body temperature. The mismatch in the coefficients of thermal expansion of the beam and the frame causes the beam to buckle in body temperature. This intentional buckling makes the beam unstable and improves the power production and robustness of the device. Having high natural frequency is a major problem in microelectromechanical systems energy harvesters. Considering the small size of the energy harvester, 0.5 cm3, the natural frequency is expected to be high. In our design, the natural frequency is lowered significantly using a buckled beam and a proof mass. Since the beam is buckled, the design is bistable and nonlinear, which could increase the output power. In this article, the device is analytically modeled, and the natural frequencies and mode shapes of the energy harvester are analytically derived. The terms corresponding to geometric nonlinearities are included in the electromechanical coupled governing equations. The simulations show that the device generates sufficient electricity to power leadless pacemakers.

A miniaturized endocardial electromagnetic energy harvester for leadless cardiac pacemakers

“…Our investigation on the device's orientation and pacing location dependency of the harvested power underline the importance that the estimated energy output in such patients is not to be overestimated based just on heart rate and a normal cardiac function. Although the described effect may vary with the harvester design, dependencies of the estimated power output on the stimulation pattern of the heart matter and were not considered by others so far [4,6,12]. The bench experiment also showed that the harvested power is well above the target power (4.2 μW) for higher heart rates.…”

“…These mechanisms were developed to either harvest energy from the heart motion, pressure variations in the heart or blood stream. Piezo-electric mechanisms can be utilized to transform a small portion of the cardiac motion or the blood pressure variations into electrical energy [4][5][6][7][8][9]. They rely on a beam structure with a proof mass, which is bent in the presence of heart motion.…”

“…Finally, energy may also be harvested from the blood flow inside the heart by a bi-stable beam coupled to an electromagnetic transducer [13]. These approaches suffer from important limitations such as invasive implantation [7][8][9][10][11], single-axis acceleration dependency [4,5,9,12], risk of blood clot formation [13], too low harvested power [6] or shape and size not adapted to be implanted inside the heart [5,[8][9][10].…”

Single‐chamber leadless pacemaker for atrial synchronous or ventricular pacing

“…10 Our previous studies have demonstrated that electrical energy transduced from ultrasound 67 The energy is then stored in a battery or capacitor of the LP and used for pacing. [72][73][74] Results of initial ex vivo and in vivo studies are encouraging. [72][73][74] Future utilization of LP technology will depend on the development of small size, high energy-density materials with longterm biosafety.…”

“…[72][73][74] Results of initial ex vivo and in vivo studies are encouraging. [72][73][74] Future utilization of LP technology will depend on the development of small size, high energy-density materials with longterm biosafety. 74…”