The paper presents a substantial review of the research done on the use of carbon nanotubes to fabricate and utilize nanogenerators. Carbon nanotubes have been one of the leading nanomaterials that have been employed to fabricate dynamic sensing prototypes. The exceptional electromechanical characteristics of carbon nanotubes have led scientists to use them in different physiomechanical forms. The use of carbon nanotubes to form the electrodes of the sensors increases the overall efficiency in terms of sensitivity, robustness and longevity. Among the sensing applications, nanogenerators are devices that have constantly been growing popular due to the continuous shortage of available energy resources in the current world. The focus has been drawn on the fabrication of nanogenerators by combining a range of materials to generate high-quality prototypes. The use of carbon nanotubes to form nanogenerators has been highlighted, where different kinds of pure and composite devices have been developed using carbon nanotubes and utilized for energy-harvesting applications. The paper also highlights some of the challenges that need to be addressed in the current scenario to improve their performances in controlled and real-time situations. 

A critical review of the recent progress on Carbon Nanotubes-based Nanogenerators

Flexible piezoelectric energy harvesters have drawn attention for their potential use as power sources for wearable electronics However, the harnessed energy cannot be directly connected to load systems Power conditioning circuits are extremely needed to achieve conditioned and rectified signals However, there is still no complete overview available, which exhaustively describes and classify the existing AC-DC rectifiers for flexible piezoelectric energy harvesting (F-PEH) In this paper, different rectifiers were investigated, compared, and evaluated The strengths and limitations of the interfaces were addressed based on the results obtained These show that for nanocomposite based F-PEH, the parallel Synchronized Switch Harvesting on Inductor (P-SSHI) resonant rectification technique delivers better performance than the full bridge, voltage doubler and CMOS rectifiers by increasing the electromechanical conversion as well as the power extraction efficiency by 200 % than the standard single-phase full bridge rectifier which has a more stable output than the half wave voltage doubler

AC-DC Single Phase Rectifiers for Nanocomposite based Flexible Piezoelectric Energy Harvesters

Wearable sensors are gaining attention in human health monitoring applications, even if their usability is limited due to battery need. Flexible nanogenerators (NGs) converting biomechanical energy into electrical energy offer an interesting solution, as they can supply the sensors or extend the battery lifetime. Herein, flexible generators based on lead-free barium titanate (BaTiO3) and a polydimethylsiloxane (PDMS) polymer have been developed. A comparative study was performed to investigate the impact of multiwalled carbon nanotubes (MWCNTs) via structural, morphological, electrical, and electromechanical measurements. This study demonstrated that MWCNTs boosts the performance of the NG at the percolation threshold. This enhancement is attributed to the enhanced conductivity that promotes charge transfer and enhanced mechanical property and piezoceramics particles distribution. The nanogenerator delivers a maximum open-circuit voltage (VOC) up to 1.5 V and output power of 40 nW, which is two times higher than NG without MWCNTs. Additionally, the performance can be tuned by controlling the composite thickness and the applied frequency. Thicker NG shows a better performance, which enlarges their potential use for harvesting biomechanical energy efficiently up to 11.22 V under palm striking. The voltage output dependency on temperature was also investigated. The results show that the output voltage changes enormously with the temperature.

/pdf/collaborative-filler-network-for-enhancing-the-performance-25b25rjg.pdf

Collaborative Filler Network for Enhancing the Performance of BaTiO3/PDMS Flexible Piezoelectric Polymer Composite Nanogenerators

Owing to the growing number of personal electronic devices and the resulting growing global energy consumption have necessitated the development of efficient and flexible electronic devices to harvest energy, nanogenerator based on piezoelectric principle is one of those smart devices that offers the required properties, and can converts mechanical energy such as human motion into electrical energy. Piezoelectric nanocomposite based on lead-free BCZT nanoparticles and PDMS polymer has shown excellent piezoelectric property. In this paper, BCZT was synthesized using a sol-gel method to increase the particles piezoelectric coefficient. Different nanogenerators have been realized based on different concentration of BCZT. Nanogenerator with (15 wt. % BCZT) ows outstanding output performance with open circuit voltage of 13 V and output power P=2.218 μW for resistance R=370 kΩ using the shaker device. Keywords—BCZT, flexible nanogenerator, impedance

Lead-Free Ba<inf>0.85</inf>Ca<inf>0.15</inf>Zr<inf>0.1</inf> Ti<inf>0.1</inf>O<inf>3</inf> for High Piezoelectric Performance Flexible Nanogenerator

Flexible and environment friendly piezoelectric nanogenerators are attracting substantial attention due to environmental constraints and ecological considerations of energy harvesting. In this paper, self-poled and bio-flexible piezoelectric nanogenerators (BF -PEN G) were developed based on lead-free BCZT and BCZT-0.02Sn nanoparticles that were synthesized using sol-qel method and embedded with PDMS polymer. To investigate the impact of doping, electrical and mechanical characterizations were conducted as well piezoelectric measurements. The results illustrate that PENG containing BCZT doped with 0.02 Sn shows higher performance comparing to PENG with BCZT. It can generate open circuit voltage of 4V under vibration shaker and 30 V under gentle finger tapping. This good piezoelectric performance is related to the enhanced mechanical behavior in addition to the enhanced conductivity with the integration of Sn within BCZT nanoparticle.

Enhancing electrical and mechanical by Sn doping in BCZT for high performance nanogenerators

Recently, the demand for flexible and wearable nanogenerators (NGs) have been paid great of attention to convert mechanical energy such as human motion into electrical energy. NGs are known by their simple structure and excellent piezoelectric performance after polarization. However, the polarization is very long and unsafe. In order to avoid that, the proposed solution was to dope multiwalled carbon nanotubes (MWCNTs) for better distribution of piezoelectric nanoparticles. In this work, piezoelectric nanocomposite generators were prepared using solution mixing and mold casting. A comparative study was performed to investigate the impact of MWCNTs via morphological and mechanical testing. Both nanogenerators shows good performance due to high uniformity of nanoparticle distribution within the polymer matrix showing the efficiency of the adapted fabrication process. In addition, doping multiwalled carbon nanotube (MWCNTs) within the piezoelectric nanocomposite leads to increase the output voltage by about 20% comparing to the NG without carbon nanotube (CNTs) which corresponds to 6.6 V and a power of ~37.87 μW at a load resistance of about 660 kΩ due to the enhanced distribution of the nanoparticle and better electro-mechanical coupling.

Ajay

Papers

Carbon nanotubes for high performance flexible piezoelectric polymer composite nanogenerators