A flexible single-crystalline PMN-PT piezoelectric energy harvester is demonstrated to achieve a self-powered artificial cardiac pacemaker. The energy-harvesting device generates a short-circuit current of 0.223 mA and an open-circuit voltage of 8.2 V, which are enough not only to meet the standard for charging commercial batteries but also for stimulating the heart without an external power source.

We developed a three-dimensional spring-type piezoelectric energy harvester using a dip-coating method and multi-directional electrode deposition. The energy harvester consists of a bilayered structure composed of a surface electrode and a ferroelectric polymer, on a conventional spring which has two rolesthe core electrode and the mechanical substrate for the ferroelectric polymer. The energy harvester generated an output voltage of up to 88 mV as a function of cycling compression stress, which leads to a piezoelectric constant of 28.55 pC N 21 for unpoled P(VDF-TrFE) films. Since the spring structure significantly decreases the resonance frequency of the harvester, the springtype energy harvester can effectively generate electricity using low-frequency vibration energy abundant in the nature.Vibration-based energy harvesting (VEH) devices have attracted great interest for use as sustainable and clean electric power supplies for wireless sensor networks that enable health monitoring of important infrastructures such as power plants, bridges and remote power grids. [1][2][3] Since there are abundant vibration sources with a low frequency (between 1 and 200 Hz) in nature, 4 low frequency vibrations are of high interest and are targeted in VEH device design for a wide range of potential applications. [5][6][7][8][9][10] Several approaches exist to convert vibrations to electrical power including electromagnetic, electrostatic and piezoelectric conversion, among which piezoelectric energy harvesting systems (PEHSs) have received the most attention. This is because they directly convert applied mechanical energy into electricity, leading to a simpler device design in comparison to other mechanisms, which require complex geometries and numerous additional components. 1 However, PEHSs are facing challenges such as low output power and high resonance frequency. 8 As the resonant frequency

A self‐powered artificial pacemaker is demonstrated using a high‐performance flexible piezoelectric PMN‐PT thinfilm energy harvester. As reported by K. J. Lee and co‐workers on page 4880, a PMN‐PT harvesting device can convert slight mechanical movements to high electric power and provides functional electrical stimulation of a living heart.

We investigated the effects of annealing temperature and vacuum treatment on the crystallinity and ferroelectric properties of solution‐casted poly(vinylidenefluoride‐co‐trifluoroethylene), P(VDF‐TrFE), thick films. We varied the annealing temperature from 70°C to 150°C and achieved high‐quality ferroelectric thick films annealed at 130°C. Ferroelectric domains and their properties were confirmed using X‐ray diffraction, Fourier transform infrared spectroscopy with attenuated total reflection mode and ferroelectric/piezoelectric measurement systems. Drying and/or annealing in the vacuum allowed for the improvement of crystallinity and ferroelectric/piezoelectric properties. Importantly, the piezoelectric coefficient, d33, of our optimal P(VDF‐TrFE) films after sufficient poling treatment was 36 pC/N and our P(VDF‐TrFE) power generator produced an output voltage of ∼6 V under periodic bending and unbending motions. POLYM. ENG. SCI., 54:466–471, 2014. © 2013 Society of Plastics Engineers

Here, we demonstrate a novel process to convert TiO 2 nanotubes into ferroelectric nanohoneycombs, comprised of vertically aligned PbTiO 3 nanotubes. Tube bottom opening process enabled effective infiltration of lead acetate precursor into the nanotubes. Nanohoneycombs, which were converted via additional lead supplement process, showed uniform conversion and well-defined ferroelectric properties with the effective piezoelectric coefficient of approximately 20 pm/V, which was measured by piezoresponse force microscopy.