Triboelectric Energy Harvesting Devices Research Articles

Advances in Bioresorbable Triboelectric Nanogenerators.

With the growing demand for next-generation health care, the integration of electronic components into implantable medical devices (IMDs) has become a vital factor in achieving sophisticated healthcare functionalities such as electrophysiological monitoring and electroceuticals worldwide. However, these devices confront technological challenges concerning a noninvasive power supply and biosafe device removal. Addressing these challenges is crucial to ensure continuous operation and patient comfort and minimize the physical and economic burden on the patient and the healthcare system. This Review highlights the promising capabilities of bioresorbable triboelectric nanogenerators (B-TENGs) as temporary self-clearing power sources and self-powered IMDs. First, we present an overview of and progress in bioresorbable triboelectric energy harvesting devices, focusing on their working principles, materials development, and biodegradation mechanisms. Next, we examine the current state of on-demand transient implants and their biomedical applications. Finally, we address the current challenges and future perspectives of B-TENGs, aimed at expanding their technological scope and developing innovative solutions. This Review discusses advancements in materials science, chemistry, and microfabrication that can advance the scope of energy solutions available for IMDs. These innovations can potentially change the current health paradigm, contribute to enhanced longevity, and reshape the healthcare landscape soon.

A study on the design parameters for water–solid triboelectric energy harvesting with a channel device

This study demonstrates a channel device to harvest energy from water flow in a channel, which can fix the water droplet’s shape and speed. By using this device configuration, design parameters like material thickness, water droplet’s speed and length, and electrode length were able to analyze independently. An electrical output is generated when different Teflon thicknesses coated on the top and bottom electrodes of the channel. The device with the overall thinnest Teflon layers can produce the highest short circuit current of 2.346 ± 0.018 nA and open-circuit voltage of 2.01 ± 0.01 V. Furthermore, the short circuit current increases with the water droplet speed in the channel. However, short circuit current output remains unchanged when the electrode and the water droplet’s length changes. For potential device application, the channel device can produce a direct current – like short circuit current output with a long duration (~1s) of constant current (Ipk = 2.358 nA). This was achieved simply by using a long electrode and water droplet length of 25 mm. The findings in this study not only provide information to understand the design parameters in water–solid triboelectric energy harvesting devices but also helpful for future device design to generate a constant current output.

Materials‐Related Strategies for Highly Efficient Triboelectric Energy Generators

AbstractSince 2012, triboelectric energy harvesting technologies have received a substantial amount of attention as they constitute one of the most efficient ways of transforming vibrational and frictional energy into electrical energy, regardless of location and environmental conditions. One of the most significant advantages of this technology is in the suitability of a very wide range of materials that can be readily incorporated into devices. In order to achieve efficient energy harvesting performance, advances in materials science and nanotechnology have been applied to develop high‐performance triboelectric energy harvesters, which have witnessed a tremendous growth in popularity. However, even though a large number of materials, including polymers, metals, inorganic and composite materials, have been separately studied for triboelectric energy harvesting applications, the key features of these different classes of materials have never been presented together or summarized, to provide valuable insight for future materials development in this field. Here, a comprehensive review of the up‐to‐date materials‐driven progress of triboelectric energy harvesting devices is provided, with emphasis on the study of materials‐related operating mechanisms and emergent materials design strategies for highly efficient triboelectric devices. The discussion includes several issues and challenges that need to be addressed for further improvement of triboelectric devices.

Nylon‐11 nanowires for triboelectric energy harvesting

AbstractTriboelectric energy harvesting from ambient mechanical sources relies on motion‐generated surface charge transfer between materials with different electron affinities. In order to achieve highly efficient energy harvesting performance, choosing materials with a high surface charge density is crucial, and odd‐numbered polyamides (Nylons), such as Nylon‐11, are particularly promising due to their strong electron‐donating characteristics and the possibility to achieve dipolar alignment leading to high surface potential. The use of Nylon‐11 as a material for triboelectric energy harvesting has been rather limited due to the extreme processing conditions required for film fabrication, and the high‐voltage poling process required for dipole alignment. However, several methods to achieve “self‐poled” Nylon‐11 nanowires via facile nanoconfinement techniques have been demonstrated recently, leading to highly efficient Nylon‐11 nanowire‐based triboelectric nanogenerators. Here, we review the most recent advances in the fabrication of Nylon‐11 nanowires, with a focus on how nanoconfinement‐based fabrication methods can be used to control phase and crystallinity. These growth methods lead to self‐poled nanowires without the requirement for subsequent electrical poling, facilitating their integration into triboelectric energy harvesting devices. Strategies to fabricate Nylon‐11 nanowires for applications in triboelectric devices can be extended to other polymeric families as well.image

Experimental study of resistive load for impedance matching of triboelectric energy harvester fabricated with patterned polydimethylsiloxane polymer layer

Impedance matching of the power source with the external load is one of the imperative parameters of any electronic system for the optimized power transfer from the power source to the load. Mismatch in impedance of power source and the external load may cause a drastic reduction in the power transfer due to reflections. In this paper, a systematic experimental study of load matching between energy harvester and load resistance has been presented. The experimental results showed output voltage without external load condition is 68.46 V with the output current of 14.59 µA, consequently instantaneous power of 0.937 mW. Under the optimum load of 4 MΩ, the output power reduced to 0.248 mW. A rigorous experimental study has been carried out under the frequency and force of 4.5 Hz and 2.8 N, respectively. The triboelectric energy harvester device has also been demonstrated for the potential applications of the self-sustained system.

Performance enhancement of the triboelectric energy harvester by forming rough surface polymer film using poly-dimethyl-siloxane +25 wt% water solution

In this paper, an experimental study of performance enhancement of the triboelectric energy harvester (TEH) by using rough surface poly-dimethyl-siloxane (PDMS) polymer film as one of the tribo layer has been presented. A parallel plate vertical-separation mode type TEH has been fabricated with rough surface morphology PDMS polymer film. Rough surface morphology is formed by spin coating diluted PDMS formed of Dow Corning 10:1 PDMS solution +25wt% water on the FR4 PCB board. FR4 substrate with single side copper clad has been utilised to realise bottom electrode. A cantilever structure is implemented utilising 50 μm thin copper foil, as top electrode, attached beneath a Kapton film. The device performance measurements showed the peak output voltage of 39.69 V and peak to peak voltage of 53.75 V. As a proof of concept, self-powered light emitting diodes (LED) system with 26 serially connected LEDs has been demonstrated with manual tapping on the TEH device.

Body-Integrated Self-Powered System for Wearable and Implantable Applications.

The human body has an abundance of available energy from the mechanical movements of walking, jumping, and running. Many devices such as electromagnetic, piezoelectric, and triboelectric energy harvesting devices have been demonstrated to convert body mechanical energy into electricity, which can be used to power various wearable and implantable electronics. However, the complicated structure, high cost of production/maintenance, and limitation of wearing and implantation sites restrict the development and commercialization of the body energy harvesters. Here, we present a body-integrated self-powered system (BISS) that is a succinct, highly efficient, and cost-effective method to scavenge energy from human motions. The biomechanical energy of the moving human body can be harvested through a piece of electrode attached to skin. The basic principle of the BISS is inspired by the comprehensive effect of triboelectrification between soles and floor and electrification of the human body. We have proven the feasibility of powering electronics using the BISS in vitro and in vivo. Our investigation of the BISS exhibits an extraordinarily simple, economical, and applicable strategy to harvest energy from human body movements, which has great potential for practical applications of self-powered wearable and implantable electronics in the future.

Remarkable Output Power Density Enhancement of Triboelectric Nanogenerators via Polarized Ferroelectric Polymers and Bulk MoS2 Composites.

Performance enhancement of triboelectric nanogenerators (TENGs) has been largely limited by the relatively low output current density. Thus, extensive research efforts have been made to increase the output current density. In this respect, this work presents a method to effectively increase output current density of TENGs by adopting polarized ferroelectric polymers and MoS2 composite. Specifically, by compositing bulk MoS2 flakes with both Nylon-11 and PVDF-TrFE, respectively, charge density of each triboelectric charging surface was significantly increased. In addition, proper polarization of both ferroelectric composite layers has also led to an additional increase in the charge density. A combination of them synergistically increases the surface charge density, generating huge output current and the power output density. By optimizing the fabrication process, the output voltage and current density up to ∼145 V and ∼350 μA/cm2 are achieved, respectively. Consequently, the TENG exhibits a recordable output power density of ∼50 mW/cm2, which is one of the highest output power densities reported to date. The method introduced in this work can greatly increase the output current density of TENGs, facilitating the development of high-performance triboelectric energy harvesting devices.

A sandpaper assisted micro-structured polydimethylsiloxane fabrication for human skin based triboelectric energy harvesting application

This paper reports a sandpaper based inexpensive and simple fabrication process of functional micro-structured PDMS (Polydimethylsiloxane) film to be used as a triboelectric layer. The micro-structured PDMS film was replicated directly from the low surface energy sandpaper template without the use of any surfactant coating, high vacuum or high-pressure equipment. A human skin and PDMS interaction based triboelectric generator (TEG) is demonstrated using as-fabricated micro-structured PDMS film. In our proposed TEG harvester, electrical energy is produced by continual contact-separation processes between PDMS and human skin. Four different micro-structures were compared with flat film and the influences of surface structures on the electrical output of the harvester are systematically studied. Results show that the existence of micro-structures on the PDMS films effectively enlarges the contact area and provides more surfaces for charge storage and hence improve the output performance of TEG. The as-fabricated prototype can produce peak-peak open-circuit voltage up to 103V and 4.8mW/m2 of peak power density, which is exceptionally attractive for the fabrication of self-powered and portable devices. This stable PDMS film with functional micro-structures, which is fabricated using reusable sandpaper template facilitates robust and large-scale fabrication, and has potential for future applications in triboelectric energy harvesting devices.

(Invited) Flexible Piezo-, Tribo-Electric Energy Harvesting Devices for Self-Powered Nanosensor Systems

Flexible devices have been drawn a great attention as next-generation electronic devices. Especially for flexible and wearable system, the challenge to achieve such systems are the development of functional and flexible new materials and unique integration method of conventional devices into flexible ones including high performances. Nevertheless, such nanosystem also requires a power source to make the entire package small, sustainable and even long lasting. In this regards, harvesting energy from the environment is a choice for powering nanosystems. As for the goal, it is desired to explore flexible and wearable devices for scavenging energy around our surroundings, thus it can supply the power to nanosensor system without consuming much battery or to supporting battery life. Here, we will present some approaches for converting mechanical energy into electric energy using piezoelectric or triboelectric effects. This technology may make it possible to harvest energy from certain mechanical movements or human activity. Moreover, self-powered nano-sensor systems have been fabricated by combining the energy harvesting technology which ensures its compatibility and perspective. The presentation will be continuously dedicated to recent developments and improvements of energy harvesting technology towards self-powered nano-systems such as mobile electronics and wearable healthcare.

Performance enhancement for the triboelectric energy harvester by using interfacial micro-dome array structures

Interfacial micro-dome array structures are proposed to enhance the performance of triboelectric energy harvester (TEH) devices. With the designed process flow for the demonstration of the interfacial micro-dome array structures, open-circuit voltage (Voc) is found to be improved about 2 times compared with the previously reported micro-pyramid array TEH device. The modeling, simulation, visualization experiment, and electrical measurements are conducted and analyzed to clarify the impact of the different interfacial microarray structures in the TEH devices. We conclude that the proposed micro-dome array TEH device indeed can result in the best output power density, Voc, pressure sensing sensitivity, and pressure sensing range.

Inductively coupled plasma surface modification of polyethylene terephthalate and application in a triboelectric generator

We herein report our investigation into the effect of plasma-induced surface modification of a polyethylene terephthalate (PET) surface on the output performance of a triboelectric generator (TEG). The PET surface was subjected to plasma treatment using a CF4/CH4/Ar gas mixture (25–75% CF4) to increase the surface roughness and triboelectric charge density. Plasma diagnostics were then performed using optical emission spectroscopy and a double Langmuir probe, while analysis of the surface roughness and surface characteristics was performed using atomic force microscopy and X-ray photoelectron spectroscopy, respectively. Following plasma treatment, we prepared a triboelectric energy harvester device, and demonstrated an outstanding improvement in TEG short-circuit current measurements.

Comment on “An ultrathin stretchable triboelectric nanogenerator with coplanar electrode for energy harvesting and gesture sensing” by X. Chen, Y. Song, H. Chen, J. Zhang and H. Zhang, Journal of Materials Chemistry A, 2017, 5, 12361

The electrostatic charge issue in skin-contact type triboelectric energy harvesting devices can be overcome by an appropriate choice of materials.

High output piezo/triboelectric hybrid generator.

Recently, piezoelectric and triboelectric energy harvesting devices have been developed to convert mechanical energy into electrical energy. Especially, it is well known that triboelectric nanogenerators have a simple structure and a high output voltage. However, whereas nanostructures improve the output of triboelectric generators, its fabrication process is still complicated and unfavorable in term of the large scale and long-time durability of the device. Here, we demonstrate a hybrid generator which does not use nanostructure but generates much higher output power by a small mechanical force and integrates piezoelectric generator into triboelectric generator, derived from the simultaneous use of piezoelectric and triboelectric mechanisms in one press-and-release cycle. This hybrid generator combines high piezoelectric output current and triboelectric output voltage, which produces peak output voltage of ~370 V, current density of ~12 μA·cm−2, and average power density of ~4.44 mW·cm−2. The output power successfully lit up 600 LED bulbs by the application of a 0.2 N mechanical force and it charged a 10 μF capacitor to 10 V in 25 s. Beyond energy harvesting, this work will provide new opportunities for developing a small, built-in power source in self-powered electronics such as mobile electronics.

Investigation of contact electrification based broadband energy harvesting mechanism using elastic PDMS microstructures

Triboelectric energy harvesting has recently garnered a lot of interest because of its easy fabrication and high power output. Contact electrification depends on the chemical properties of contacting materials. Another important factor in contact electrification mechanism is surfaces’ elastic and topographical characteristics. One of the biggest limitations of resonant mechanism based devices is their narrow operating bandwidth. This paper presents a broadband mechanism which utilizes stiffness induced in the cantilever motion due to contact between two triboelectric surfaces. We have conducted experiments using polydimethylsiloxane (PDMS) micropad patterns to study the effect of micropad array configuration on the performance of triboelectric energy harvesting devices. The maximum power output measured from the device was observed to be 0.69 μW at an acceleration of 1 g. Due to the non-linearity introduced by contact separation mechanism, the bandwidth of the triboelectric energy harvester was observed to be increased by 63% at an acceleration level of 1 g. A hybrid energy harvesting mechanism has also been demonstrated by compounding the triboelectric energy harvester with a piezoelectric bimorph.