Liquid-phase tuning of porous PVDF-TrFE film on flexible substrate for energy harvesting

Adv Materials Technologies

Chen

Liu

et al. 2018

Self Cite

Self‐sustainable energy generation represents a new frontier to significantly extend the lifetime and effectiveness of implantable biomedical devices. In this work, a piezoelectric energy harvester design is employed to utilize the bending of the lead of a cardiac pacemaker or defibrillator for generating electrical energy with minimal risk of interfering with cardiovascular functions. The proposed energy harvester combines flexible porous polyvinylidene fluoride–trifluoroethylene thin film with a buckled beam array design for potentially harvesting energy from cardiac motion. Systematic in vitro experimental evaluations are performed by considering complex parameters in practical implementations. Under various mechanical inputs and boundary conditions, the maximum electrical output of this energy harvester yields an open circuit voltage (peak to peak) of 4.5 V and a short circuit current (peak to peak) of 200 nA, and that energy is sufficient to self‐power a typical pacemaker for 1 d. A peak power output of 49 nW is delivered at an optimal resistor load of 50 MΩ. The scalability of the design is also discussed, and the reported results demonstrate the energy harvester's capability of providing significant electrical energy directly from the motions of pacemaker leads, suggesting a paradigm for biomedical energy harvesting in vivo.

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Piezoelectric Buckled Beam Array on a Pacemaker Lead for Energy Harvesting

Adv Materials Technologies

Chen

Liu

et al. 2018

Self Cite

“…The piezoelectric coefficients of β‐phase of PVDF‐TrFE were found 20–30 pC N −1 ( d 33 ) and 16–18 pC N −1 ( d 31 ), which are sufficient to generate useful levels of electrical outputs . Recent studies showed the piezoelectric output has been enhanced by threefold through the optimization of PVDF‐TrFE porous structure and electromechanical coupling efficiency compared to solid PVDF‐TrFE thin film . Specifically, the mechanical flexibility of the porous PVDF‐TrFE thin film can be tuned by controlling the porous structure, such as the pore diameter and porosity, through the water vapor phase separation method .…”

Section: Methodsmentioning

confidence: 99%

Flexible Porous Piezoelectric Cantilever on a Pacemaker Lead for Compact Energy Harvesting

Adv Materials Technologies

Han

Xü

et al. 2018

Self Cite

ventricular dysrhythmias, and congestive heart failure. [1] Currently, lithium-based batteries provide the power for operations of implantable biomedical devices, such as cardiac pacemakers and AICD. Although the advances in microelectronics technology reduce the internal current drain concurrently allowing for a smaller volume and greater reliability of implantable biomedical devices, the batteries used in those devices only have a few years operating lifetime. Patients are still exposed to health risks associated with doing periodic surgeries to replace the depleted lithium-based batteries of the implantable biomedical devices. Therefore, energy consumption and battery replacement are key to the lifetime and effectiveness of implantable biomedical devices. This work represents an effort in tackling the challenges in extending the lifetime of the batteries for such biomedical devices as cardiac pacemakers and AICDs.Given the advances in low power consumption in implantable biomedical devices (such as 0.3 µW for cardiac activity sensing, [2] 10-100 µW for pacemakers, [3,4] 100-2000 µW for cochlear implant, [5] and 1-10 mW for neural recording [6] ), it is desirable to make them self-sustainable by having their own renewable power supply. One promising way to provide this alternative power source is by means of energy harvesting, i.e., to convert the source energy to electrical energy in order to power implantable biomedical devices. Emerging new approaches on energy harvesting for powering biomedical devices are discussed in the literature. [7][8][9][10][11] In recent development, in vivo studies have been conducted to further advance the energy harvesting capabilities of these devices in living systems. [12,13] For example, a piezoelectric energy harvesting device using single crystalline (1-x) Pb(Mg 1/3 Nb 2/3 )O 3-x PbTiO 3 (PMN-PT) was implanted into the heart of a live rat and the device was then used to show functional electrical stimulation of the heart. [14] Heartbeats of pigs were also used to power wireless communication systems, [15] of which the integration with energy harvesting devices would allow for further implementation into implantable medical devices. Moreover, implantable triboelectric nanogenerators (iTENG) have been employed to convert the mechanical energy from the contraction from breathing of a rat to electricity, which was then used to power a pacemaker. [16] In another application, Self-sustainable energy generation represents a new frontier to greatly extend the lifetime and effectiveness of implantable biomedical devices, such as cardiac pacemakers and defibrillators. However, there is a lack of promising technologies which can efficiently convert the mechanical energy of the beating heart to electrical energy with minimal risk of interfering with the cardiovascular functions. Here a unique design is presented based on existing pacemaker leads tailored for compact energy harvesting. This new design incorporates flexible porous polyvinylidene fluoride-trifluoroethylene thin film withi...

“…Following the spin-coating process, the liquid-phase PVDF-TrFE/SWCNT layer was then immediately transferred into the humidity chamber where the relative humility was maintained at a constant 90% (at 37°C) for more than 4 hours. 1920 Throughout this step, the water droplets were able to enter the polymer-rich matrix and form the mesoporous structures in Figure 1(B) and (C). Due to the principle of pore formation in the PVDF-TrFE film, the majority of single-wall carbon nanotubes (SWCNTs) were embedded in the wall of mesoporous structure, but few SWCNT bundles can still be observed shown in Figure 1(D).…”

Section: Introductionmentioning

confidence: 99%

Tunable Buckled Beams with Mesoporous PVDF-TrFE/SWCNT Composite Film for Energy Harvesting

Xü

Liu

ACS Appl. Mater. Interfaces

et al. 2018

By incorporating mesoporous piezoelectric materials and tuning mechanical boundary conditions a simple beam structure can significantly take advantage of limited mechanical displacements for energy harvesting. Specifically, we employed a mesoporous PVDF-TrFE composite thin film mixed with single wall carbon nanotubes to improve the formation of the crystalline phase in this piezoelectric polymer. The film was then patterned on a thin buckled beam to form a compact energy harvester, which was used to study the effects of two boundary conditions, including the end rotation angle and the location of a mechanical stop along the beam. We carefully designed controlled experiments using mesoporous PVDF-TrFE film and PVDF-TrFE/SWCNT composite films, both of which were tested under two cases of boundary conditions, namely, the rotation of the end-angle and the addition of a mechanical stop. The voltage and current of the energy harvester under these two boundary conditions were respectively increased by approximately 160.1% and 200.5% compared to the results of its counterpart without imposing any boundary conditions. Thereby, our study offers a promising platform for efficiently powering implantable and wearable devices for harnessing energy from the human body which would otherwise have been wasted.