Search

Here, a highly sensitive triboelectric bending sensor in non-contact mode operation, less sensitive to strain, is demonstrated by designing multiple triangular prisms at both sides of the polydimethylsiloxane film. The sensor can detect bending in a strained condition (up to 20%) as well as bending direction with quite high linear sensitivity (~0.12/degree) up to 120°, due to the electrostatic induction effect between Al and poly (glycerol sebacate) methacrylate. Further increase of the bending angle to 135° significantly increases the sensitivity to 0.16/degree, due to the contact electrification between them. The sensors are attached on the top and bottom side of the proximal interphalangeal and wrist, demonstrating a directional bending sensor with an enhanced sensitivity. [ABSTRACT FROM AUTHOR]

The demand for energy harvesting technologies has been increasing over the years attributed to its significance to low power applications. One of the key problems associated with the vibration-based harvester is the fact that these harvesters generate low usable power while maximum peak power can only be attained when the device frequency matches the source frequency. In this study, triboelectric mechanism was investigated in combination with the piezoelectric mechanism in order to enhance the performance of the harvester. Triboelectric mechanism functions in a way that two dissimilar materials were placed in contact and then separated in order to generate surface charges and electric potential between them. Main design factors such as materials, surface area, structure, effective length, and etc. play a significant part in the enhancement of the performance. This study proposed two distinct designs of dual cantilevered structure and touch-based triboelectric energy harvester and evaluated the efficiency of the output between both structures. In addition, the effect of extension and surface area of triboelectric materials was investigated while the influence of these factors on the performance of the harvester was evaluated. The highest value of peak power obtained for dual cantilevered hybrid harvester was 650 µW across a load of 160 kΩ and frequency of 26 Hz. On the other hand, touch-based energy harvester produced an output peak power of 1220 µW across a load of 400 kΩ at 25 Hz. Achieving these power outputs may be able to power up electronics such as smartwatches, hearing aid and etc. Future studies on reliable low power applications to further advance the green power technology will be investigated.

Abstract Energy harvesting devices based on the triboelectric effect have attracted great attention because of their higher output performance compared to other nanogenerators, which have been utilized in various wearable applications. Based on the working mechanism, the triboelectric performance is mainly proportional to the surface charge density of the triboelectric materials. Various approaches, such as modification of the surface functional group and dielectric composition of the triboelectric materials, have been employed to enhance the surface charge density, leading to improvements in triboelectric performances. Notably, tuning the dielectric properties of triboelectric materials can significantly increase the surface charge density because the surface charge is proportional to the relative permittivity of the triboelectric material. The relative dielectric constant is modified by dielectric polarization, such as electronic, vibrational (or atomic), orientation (or dipolar), ionic, and interfacial polarization. Therefore, such polarization represents a critical factor toward improving the dielectric constant and consequent triboelectric performance. In this review, we summarize the recent insights on the improvement of triboelectric performance via enhanced dielectric polarization.

Wearable self-powered sensors represent a theme of interest in the literature due to the progress in the Internet of Things and implantable devices. The integration of different materials to harvest energy from body movement or the environment to power up sensors or act as an active component of the detection of analytes is a frontier to be explored. This review describes the most relevant studies of the integration of nanogenerators in wearables based on the interaction of piezoelectric and triboelectric devices into more efficient and low-cost harvesting systems to power up batteries or to use the generated power to identify multiple analytes in self-powered sensors and biosensors.

With the rapid development of wireless communication and micro-power technologies, smart wearable devices with various functionalities appear more and more in our daily lives. Nevertheless, they normally possess short battery life and need to be recharged with external power sources with a long charging time, which seriously affects the user experience. To help extend the battery life or even replace it, a non-resonant piezoelectric–electromagnetic–triboelectric hybrid energy harvester is presented to effectively harvest energy from low-frequency human motions. In the designed structure, a moving magnet is used to simultaneously excite the three integrated energy collection units (i.e., piezoelectric, electromagnetic, and triboelectric) with a synergistic effect, such that the overall output power and energy-harvesting efficiency of the hybrid device can be greatly improved under various excitations. The experimental results show that with a vibration frequency of 4 Hz and a displacement of 200 mm, the hybrid energy harvester obtains a maximum output power of 26.17 mW at 70 kΩ for one piezoelectric generator (PEG) unit, 87.1 mW at 500 Ω for one electromagnetic generator (EMG) unit, and 63 μW at 140 MΩ for one triboelectric nanogenerator (TENG) unit, respectively. Then, the generated outputs are adopted for capacitor charging, which reveals that the performance of the three-unit integration is remarkably stronger than that of individual units. Finally, the practical energy-harvesting experiments conducted on various body parts such as wrist, calf, hand, and waist indicate that the proposed hybrid energy harvester has promising application potential in constructing a self-powered wearable system as the sustainable power source. [ABSTRACT FROM AUTHOR]

• Electrically conductive ceramic/polymer nanocomposites were fabricated. • The content of conductive carbon black (CB) nanoparticles was varied. • A Turbiscan and a rheometer were used to assess the dispersion of nanocomposites. • A universal percolation network with imperfect/tunneling interfaces was confirmed. • The electrical conductivity considerably improved with increasing contents of CB. A book-shaped all-in-one energy harvester module with a piezo-triboelectric hybrid structure as a next-generation eco-friendly energy source was manufactured based on flexible piezoceramic nanofibers with enhanced current characteristics obtained by controlling the added amount of carbon black (CB). To prepare flexible piezoceramic nanofibers with favorable current properties, 0.78Bi 0.5 Na 0.5 TiO 3 −0.22SrTiO 3 (BNT-ST) piezoelectric ceramics were composited with CB, a highly conductive material, and then electrospun with a poly(vinylidene fluorideco–trifluoroethylene) polymer. The prepared CB/BNT-ST nanofibers were modularized into piezoelectric energy harvester modules (PEHMs) with interdigitated electrodes, yielding an improved output performance with a high voltage of 10.1 V and high current of 2.02 nA. A book-shaped triboelectric energy harvester module (TEHM) was manufactured with polydimethylsiloxane on one side and the CB/BNT-ST nanofibers on the other side, affording an improved output performance with a high voltage of 391 V and high current of 130 μA. A book-shaped all-in-one hybrid energy harvester module (HEHM) was then manufactured by fitting PEHMs at both ends of the book-shaped TEHMs. As a result of optimizing the output performance by connecting HEHM multiple layers, a high voltage and current of 1043 V and 579 μA were observed, respectively, and charging of a 1.0 μF capacitor was completed in 25 s. Furthermore, in simulated energy harvesting experiments using the all-in-one HEHM, LED light bulbs were clearly illuminated in real time, and an electronic calculator was operated without charging. This work suggests the application potential of the all-in-one HEHM as the next generation of eco-friendly flexible energy sources. [ABSTRACT FROM AUTHOR]

Scavenging mechanical vibration energy by combining triboelectric nanogenerators (TENGs) and electromagnetic generators (EMGs) is a renewable and low-carbon way to generate electric power. In this paper, we fabricate a cylindrical structure hybrid nanogenerator based on spring structure to effectively scavenge vibration energy. The introduction of spring structure not only enhances the space utilization, but also supports the moving magnet. Owing to its innovative structure, the instantaneous output power of TENG and EMG are 0.88 mW at a load of 10 MΩ and 216.7 mW at a load of 60 Ω, respectively. With the aids of a power management circuit, the hybrid nanogenerator can provide continuous power for two hygrothermographs connected in series. In addition, a self-powered wireless acceleration sensing monitoring system (SWAM) is developed to measure the acceleration signals of vibration sources. This study provides a novel guideline for harvesting mechanical vibration energy. [ABSTRACT FROM AUTHOR]

This paper investigates an approach to impact vibration energy harvesting using a triboelectric mechanism under harmonic and random excitation. The harvester consists of a clamped–clamped beam with a stiff plate in the middle to realize the impact electrification process when subjected to external vibrations. The harvester uses stiffening in the clamped–clamped beam introduced by the impact between two triboelectric layers to increase the frequency bandwidth. A piecewise theoretical model is used to model the harvester for two scenarios of motions, before and after impact. The harvester is tested experimentally under different harmonic excitation to validate the theoretical model. The outcomes show a good agreement between both experimental and theoretical results. Higher bandwidth is achieved at a lower gap separation distance. The operating bandwidth of the energy harvester increased from 4.4 Hz to 17.8 Hz with an RMS output voltage level of 7 V and an output power density of 7mW∕m2at 1.4 g excitation level and 100μmgap. The model is extended and validated experimentally under random excitation. The simulated power spectral densities are in good agreement with the experimental results.

Valuable jewels, documents, and files left in hotel rooms by guests can be stolen at any time by an unauthorized person. This could have a serious psychological and economic impact on the guests. The house/hotel owners should make efforts to prevent theft from occurring. In this study, a self-powered sliding-mode triboelectric nanogenerator (TENG) is used as a sensor on a drawer. It is fixed to the side of the drawer and works in the lateral sliding mode. The electricity generated by the device during the push–pull action of the draw is ~125 V and F~12.5 µA. An analysis of the electrical performance was carried out using PET, paper, and nitrile as sliding materials. The electrical output from the device is used to notify the guest or hotel owner of any theft by an unidentified individual via Arduino and node MCU devices. Finally, this device can be helpful at night and can be extended using different materials.

The self-powered triboelectric touch panel has garnered considerable research attention due to its potential to reduce system energy consumption and its applications in human-machine interfaces, e-skin, and the Internet of Things. Current methods for achieving triboelectric-based touch positioning in an M × N detection pixel array typically require signal amplitude comparison across at least M + N signal channels, thereby limiting lightweight design possibilities. In contrast, our novel "resistor ladder" approach necessitates only 4 signal channels for touch positioning. This method leverages a lookup table correlating touch positions with amplitude ratios from different channels, rendering it insensitive to signal amplitude and significantly enhancing robustness. We fabricated a transparent touch panel using PET tribomaterial, where the surface roughness was enhanced through plasma treatment. The panel successfully demonstrated touch positioning for 128 taps within a 4 × 4 pixel detection array and sliding positioning using a predefined lookup table. To further enhance device robustness, a 2D convolutional neural network was implemented, which achieved an impressive touch positioning accuracy of 97.7% even under artificially introduced signal defects. This study represents an initial exploration of amplitude-insensitive touch and sliding positioning methods, significantly reducing the number of required signal channels and enhancing the robustness of triboelectric touch panels.

Biosensors have emerged as vital tools for the detection and monitoring of essential biological information. However, their efficiency is often constrained by limitations in the power supply. To address this challenge, energy harvesting systems have gained prominence. These off-grid, independent systems harness energy from the surrounding environment, providing a sustainable solution for powering biosensors autonomously. This continuous power source overcomes critical constraints, ensuring uninterrupted operation and seamless data collection. In this article, a comprehensive review of recent literature on energy harvesting-based biosensors is presented. Various techniques and technologies are critically examined, including optical, mechanical, thermal, and wireless power transfer, focusing on their applications and optimization. Furthermore, the immense potential of these energy harvesting-driven biosensors is highlighted across diverse fields, such as medicine, environmental surveillance, and biosignal analysis. By exploring the integration of energy harvesting systems, this review underscores their pivotal role in advancing biosensor technology. These innovations promise improved efficiency, reduced environmental impact, and broader applicability, marking significant progress in the field of biosensors., (© 2024 Wiley‐VCH GmbH.)

Electronic skins (E-Skins) are crucial for future robotics and wearable devices to interact with and perceive the real world. Prior research faces challenges in achieving comprehensive tactile perception and versatile functionality while keeping system simplicity for lack of multimodal sensing capability in a single sensor. Two kinds of tactile sensors, transient voltage artificial neuron (TVAN) and sustained potential artificial neuron (SPAN), featuring self-generated zero-biased signals are developed to realize synergistic sensing of multimodal information (vibration, material, texture, pressure, and temperature) in a single device instead of complex sensor arrays. Simultaneously, machine learning with feature fusion is applied to fully decode their output information and compensate for the inevitable instability of applied force, speed, etc, in real applications. Integrating TVAN and SPAN, the formed E-Skin achieves holistic touch awareness in only a single unit. It can thoroughly perceive an object through a simple touch without strictly controlled testing conditions, realize the capability to discern surface roughness from 0.8 to 1600 µm, hardness from 6HA to 85HD, and correctly distinguish 16 objects with temperature variance from 0 to 80 °C. The E-skin also features a simple and scalable fabrication process, which can be integrated into various devices for broad applications., (© 2024 Wiley‐VCH GmbH.)

Fluoropolymers, including polytetrafluoroethylene (PTFE, Teflon), polyvinylidene difluoride (PVDF), and fluorine kautschuk materials (FKMs, Viton) are critical polymers for applications ranging from non-stick coatings, corrosion resistant seals, semiconductor manufacturing, membranes, and energy harvesting technologies. However, the synthesis of these fluoropolymers requires the use of per- and polyfluorinated alkyl substances (PFAS) known colloquially as "forever chemicals," and as such there is a pressing need to develop alternative technologies that can serve the end-use of fluoropolymers without the environmental cost of using PFAS. Further, fluoropolymers themselves fall under the PFAS umbrella. Here, alternative mechanical-to-electrical energy harvesting polymers are reviewed and benchmarked against the leading fluoropolymer energy harvesters. These alternative technologies include nonfluoropolymer piezoelectric polymers, triboelectric nanogenerators (TENGs), ferroelectric elastomers, and flexoelectric polymers. A vision towards sustainable, non-fluoropolymer-based energy harvesting is provided., (© 2024 The Authors. Small published by Wiley‐VCH GmbH.)

Natural biopolymer materials have been of interest in wearable energy harvester technology, especially in biocompatible triboelectric nanogenerators (BTENGs), due to their biodegradable, biocompatible, nontoxic and excellent antibacterial properties. Nevertheless, obstacles concerning economical and biocompatible utilization of triboelectric nanogenerators (TENGs) continue to prevail. The natural biopolymer, chitosan (CS), is composed of a long biopolymer chain of N-acetyl glucosamine. It enables exciting opportunities for low-cost, biodegradable triboelectric nanogenerator (TENG) applications. However, the electrical output performance of CS based on TENGs is low when compared with devices constructed from synthetic polymers. Hence, to enhance electrical output performance, BaTiO3 nano-powders (BT-NPs) were embedded into the CS as dielectric material, in order to improve electrical properties by increasing the dielectric constant of the composite film. A flexible hybrid piezo/triboelectric nanogenerator, designed by BT-NPs embedded into CS (BT-NPs/CS) composite film, was constructed successfully. The effects of the BaTiO3 nano-powder (BT-NP) content on the output performance were explored systematically. The device with 5 wt% BT-NPs in CS, and a 160-μm-thick film, exhibited maximum open-circuit voltage (VOC) and transferred short-circuit current (ISC) of 110.8 V and 10 µA, respectively, as well as maximum power output of 431.8 µW. Practical and application demonstrations also were investigated, namely charged capacitors for storing energy, testing voltage stability and driving commercial LEDs. This work exhibited high electrical performance enhancement of BT-NPs/CS nanocomposite film, which demonstrated better material modification. [ABSTRACT FROM AUTHOR]

This study develops a full‐textile triboelectric bending sensor using an elastic conductive filament and a textile fabric as a tribopair, separated by two short spacer filaments between them. Bending triggers a triboelectric conversion. Such a sensor device can report bending angles in real time, with high sensitivity (0.0611 V deg−1) and linearity (goodness of fit above 0.986). By integrating multiple devices at the exact location, the sensor assembly can detect bending in different directions. This sensor device can be directly prepared on clothes, just using the clothes as one of the tribocomponents, and the preparation is simple, simply sewing the conductive filament to the targeted location on the clothes. The presence of sensors has little effect on the air permeability and fabric softness. In addition, the device is washable and can be used for multiple cycles without losing sensing ability. As a demonstration, the sensor is directly made on gloves and elbow pads to detect the finger bending and elbow joint movements successfully. Moreover, a two‐channel bending sensor is attached to the human wrist to report wrist bending direction. Such a simple sensor design has great potential to develop low‐cost, flexible, wearable bending devices for various applications. [ABSTRACT FROM AUTHOR]

The Triboelectric nanogenerators (TENGs) are Fabricated by contact between two surfaces of different materials and convert of electric loads between them. In such structures, the two contacting layers should be radically different in terms of their electric property so that one of the layers could induce positive electrical charge while the other induces a negative charge. The application of force on and friction between the two layers induce positive and negative charges. Through the electrodes in external load, the electrical charges flow as electric current. In the present study, TEGN structures fabricated of polyethylene terephthalate polymers (PET) act as electron acceptor while Polyamide (KAPTON) and polydimethylsiloxane (PDMS) act as electron donator. The resulting outputs are compared consequently. Considering the fact that the two materials are relatively identical in terms of electron donation as they are in contact with PET, the generators fabricated of KAPTON could generate 400% more power under identical conditions. Therefore, one may conclude that KAPTON could be more suitable for development of self-power system as they are more available and more environmentally compatible. [ABSTRACT FROM AUTHOR]

The unique characteristics of graphene have generated a lot of interest in the research community. A concept of utilizing graphene and its derivatives in the development of energy harvesters has just appeared in recent decades. This paper focuses on the application of reduced graphene oxide (rGO), a graphene derivative, in the development of wearable mechanical energy-harvesters to enable self-powered wearable sensing systems. Harvesting of energy has been a state-of-the-art phenomenon due to the ever-increasing requirement of power to run the sensing systems. Flexible systems that used rGO to gather energy with intensities ranging from a few microwatts to a few hundreds of microwatts have been used. Some examples are presented, focusing on the class of piezoelectric and triboelectric-based energy harvesters, with descriptions of their material composition, manufacturing methods, operating principle, and performance. Finally, the challenges and drawbacks of rGO-based energy harvesters are discussed, along with some of the potential solutions. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerators (TENG) work on the principle of tribo and contact electrification, which is a common phenomenon observed in daily life. TENGs are moving closer to commercialization, particularly for small scale energy harvesting and self-powered sensing. The toys and games industry has attracted a large audience recently with the introduction of digital toys. In this paper we embedded TENGs to power up a toy and operate during its specific application. We have modified two potential electronic demonstrator applications using TENG for lobster toy (LT-TENG) and stress ball (SB-TENG) device. The LT-TENG device generates a maximum electrical response of 60 V/2 µ A, with a power of 55 µ W and power density of 0.065 µ W m ^−2 at a load resistance value of 10 MΩ. Similarly, the SB-TENG device made of aluminum and PDMS as the triboelectric layers generates a maximum electrical output response of 800 V and 4 µ A peak to peak current with an instantaneous power of 6 mW and a power density of 3.5 mW m ^−2 respectively at a load resistance of 10 MΩ. In addition, the layers of the TENGs are packed with polyethylene to maintain the performance of the nanogenerator under harsh environmental conditions, especially with humid environments. The water resistance studies proved that the packed SB-TENG is impervious to water. The LT-TENG device is accompanied by four LEDs, and the device lights up upon actuating the handle. The SB is connected with the measuring instrument to record the quantity of force at which the SB is pressed. The adopted approach paves the way to convert these traditional toys into battery-free electronic designs and its commercialization.

A triboelectric power generator/energy harvester is an attractive option for mechanical energy harvesting for smart, wearable applications. This paper reports on the fabrication and evaluation of the energy harvesting performance of Polytetrafluoroethylene/Polyvinylidene Fluoride (PTFE/PVDF) fibre prepared using a one-step electrospinning technique. Different concentrations (0, 1, 2, 3, and 4%wt.) of the 1 μm PTFE powder in the electrospun PVDF fibre were investigated. The electrospun fibre was assembled into a nonwoven fabric mat and tested in the vertical contact separation triboelectric mode by constructing a sandwich structure with electrodes in a book-shaped assembly. The voltage output from the cyclical compressive test for fibres with 4%wt. PTFE in PVDF was five times greater than it was for the 100% PVDF electrospun fibres. The influence of adding nylon fabric as a triboelectric donor material within the assembly was explored. The output of the 4%wt. PTFE/PVDF sample was then tested with and without nylon fabric at different frequencies (3–12 Hz). The results show a further 80% increase in the output voltage with the additional nylon fabric included, and the harvester was able to illuminate up to 95 LEDs.

In recent years, energy harvesters using pendulum systems have often been applied in ultra-low-frequency environments, such as ocean waves, human motion, and structural vibration. To illustrate the research progress in pendulum-type energy harvesting, a comprehensive review is provided in the present study. Specifically, single- and double-pendulum energy harvesters based on different energy-conversion mechanisms are separately grouped. In addition, different improvement techniques and design schemes used in studies on pendulum energy harvesters are summarized. Theoretical studies have explored the dynamic characteristics of single and double pendulums. Various key aspects, including the fundamental mechanisms, optimization methods, core structures, and applications, to improve the performance of single- and double-pendulum energy harvesters are discussed. Finally, several potential research directions and applications are proposed.

Commonly encountered problems in the manipulation of objects with robotic hands are the contact force control and the setting of approaching motion. Microelectromechanical systems (MEMS) sensors on robots offer several solutions to these problems along with new capabilities. In this review, we analyze tactile, force and/or pressure sensors produced by MEMS technologies including off-the-shelf products such as MEMS barometric sensors. Alone or in conjunction with other sensors, MEMS platforms are considered very promising for robots to detect the contact forces, slippage and the distance to the objects for effective dexterous manipulation. We briefly reviewed several sensing mechanisms and principles, such as capacitive, resistive, piezoresistive and triboelectric, combined with new flexible materials technologies including polymers processing and MEMS-embedded textiles for flexible and snake robots. We demonstrated that without taking up extra space and at the same time remaining lightweight, several MEMS sensors can be integrated into robotic hands to simulate human fingers, gripping, hardness and stiffness sensations. MEMS have high potential of enabling new generation microactuators, microsensors, micro miniature motion-systems (e.g., microrobots) that will be indispensable for health, security, safety and environmental protection.

Abstract Cyberattack is one of the severe threats in the digital world as it encompasses everything related to personal information, health, finances, intellectual properties, and even national security. Password‐based authentication is the most practiced authentication system, however, is vulnerable to several attacks such as dictionary attack, shoulder surfing attack, and guessing attack. Here, a new keystroke dynamics‐based hybrid nanogenerator for biometric authentication and identification integrated with artificial intelligence (AI) is reported. Keystroke dynamics offer behavioral and contextual information that can distinguish and authorize the individuals based on their typing rhythms. The hybrid electromagnetic‐triboelectric nanogenerators/sensors efficiently convert the keystroke mechanical energy into electrical signals, which are fed into an artificial neural network based AI system. The self‐powered hybrid sensors‐based biometric authentication system integrated with a neural network achieves an accuracy of 99% and offers a promising hybrid security layer against password vulnerability.

There has been a significant increase in the number of total knee replacement (TKR) surgeries over the past few years, particularly among active young and elderly people suffering from knee pain. Continuous and optimal monitoring of the load on the knee is highly desirable for designing more reliable knee implants. This paper focuses on designing a smart knee implant consisting of a triboelectric energy harvester and a frontend electronic system to process the harvested signal for monitoring the knee load. The harvester produces an AC signal with peak voltages ranging from 10 V to 150 V at different values of knee cyclic loads. This paper demonstrates the measurement results of a PCB prototype of the frontend electronic system fabricated to verify the functionality and feasibility of the proposed approach for a small range of cycling load. The frontend electronic system consists of a voltage processing unit to attenuate high peak voltages, a rectifier and a regulator to convert the input AC signal into a stabilized DC signal. The DC voltage signal provides biasing for the delta-sigma analog-to-digital converter (ADC). Thus, the output of the triboelectric harvester acts as both the power signal that is rectified/regulated and data signal that is digitized. The power consumption of the proposed PCB design is approximately $5.35~\mu \text{W}$. Next, the frontend sensor circuitry is improved to accommodate a wider range of cyclic load. These results demonstrate that triboelectric energy harvesting is a promising technique for self-monitoring the load inside knee implants. [ABSTRACT FROM AUTHOR]

Continuous monitoring of knee implants after total knee replacement (TKR) surgery can play a significant role in increasing the patients’ satisfaction rate and extending the lifespan for those implants. The purpose of this study is to optimize the design parameters of the triboelectric energy harvesting mechanism to be embedded in knee implants and act as a battery-less health monitoring sensor. Triboelectric mechanisms convert mechanical energy into electricity, providing both power to operate and information about loads transmitted to the knee from daily life activities. Three different triboelectric energy harvesters were designed and fabricated with different sizes of micro-patterns as design parameters. The harvesters are tested under the simulated walking activity of normal humans. Results show that the harvester with the smaller micro-patterns size is better for energy harvesting. Testing at higher frequencies, all harvesters show an increase in the voltage generated. Moreover, by increasing the amplitude of the applied axial load, a higher voltage is generated. Exploring a different design parameter, which is the harvester’s material, and comparing to the previously reported baseline, Titanium-based harvester shows superior from Aluminum-based harvester’s performance. Also, a single-degree-of-freedom model is used to model the harvester. Higher applied load results in a higher contact area and more voltage generation. These findings show the promising potential of embedded triboelectric transducers to be utilized as self-powered health monitoring sensors for knee implants and similar applications. [ABSTRACT FROM AUTHOR]

Cyberattack is one of the severe threats in the digital world as it encompasses everything related to personal information, health, finances, intellectual properties, and even national security. Password‐based authentication is the most practiced authentication system, however, is vulnerable to several attacks such as dictionary attack, shoulder surfing attack, and guessing attack. Here, a new keystroke dynamics‐based hybrid nanogenerator for biometric authentication and identification integrated with artificial intelligence (AI) is reported. Keystroke dynamics offer behavioral and contextual information that can distinguish and authorize the individuals based on their typing rhythms. The hybrid electromagnetic‐triboelectric nanogenerators/sensors efficiently convert the keystroke mechanical energy into electrical signals, which are fed into an artificial neural network based AI system. The self‐powered hybrid sensors‐based biometric authentication system integrated with a neural network achieves an accuracy of 99% and offers a promising hybrid security layer against password vulnerability. [ABSTRACT FROM AUTHOR]

Triboelectric electronic skins (E‐skins) can be used as primary interactive devices for human–machine interfaces (HMIs). However, devices for seamless on‐skin operations must be soft and deformable, and attachable to and compatible with the skin. In this paper, a substrate‐free, skin‐compatible, skin‐attachable, mechanically deformable, and self‐powered E‐tattoo sticker consisting of carbon nanotubes (CNTs) and silk nanofibers (SNFs) is presented. The E‐tattoo can be imperceptibly tattooed on the skin and removed with water. When the device touches naked skin, triboelectric signals are generated. Because of the micro‐to‐nano hierarchical pores (with high surface‐to‐volume ratios), contact‐induced electrification generates a power density of ≈6 mW m−2 and pressure sensitivity of ≈0.069 kPa−1. The power generated on the tattooed skin can activate small electronic devices. Moreover, whole‐body joint movements can be monitored and tactile movements can be mapped by reading the generated electrical signals. The presented E‐tattoo system can promote the development of flexible energy and sensor systems for self‐powered, energy‐autonomous, imperceptible E‐skin devices for HMIs and artificial intelligent robotics and prostheses. [ABSTRACT FROM AUTHOR]

Triboelectricity in materials has emerged as an innovative and increasingly researched approach for acoustic sensing. Despite its promise, the field has faced significant challenges due to limited working bandwidth and sensitivity. As a result, we have developed a dual-symmetry triboelectric acoustic sensor (DS-TAS), featuring an expansive working bandwidth from 20 Hz to 200 kHz, exceptional sensitivity of 6.67 V/Pa, and a detection limit as low as 0.002 Pa. Moreover, the DS-TAS has been successfully integrated into a real-time, multi-directional ultrasonic radar system, achieving an impressively minimal detection error of less than 5 mm. This breakthrough in acoustic sensing performance positions the DS-TAS as a significant milestone for the field, with broad applications ranging from human-machine interaction to voice recognition. [Display omitted] • The sensor demonstrates a multifaceted performance spectrum. • It holds a remarkable sensitivity of 6.67 V/Pa with a wide sensing range of 0.002 Pa to 0.02 Pa. • A real-time multidirectional ultrasonic radar localization scanning system has been developed. [ABSTRACT FROM AUTHOR]

In the post-Moore's Law era, there is a growing trend towards the development of advanced electronic devices that combine sensory perception, data storage, and computation for various applications. Two-dimensional semiconductor transistors, which utilize charge storage mechanisms, present a promising avenue for future information devices. Here, we introduce a neuromorphic triboelectric charge-trapping MoTe 2 transistor with stacked high- k dielectric structure, aiming to facilitate mechano-driven logic-in-memory for neuromorphic computation. By gating through triboelectric potential, the device demonstrates superior electrical performance, including an impressive switching ratio (>105), minimal off-state current (∼0.6 pA), and robust cyclic stability. By modulating the trapped charges in the stack gate structure via tribopotential modulation, the conductivity state of the MoTe 2 channel can be readily controlled, realizing an exceptional mechano-driven nonvolatile memory with a retention time of up to 104 seconds, consistent switching behavior over 100 cycles, and multi-level data storage capabilities at 8 levels. Furthermore, a mechano-driven programmable inverter can be achieved by connecting a load resistor in series. The triboelectric charge-trapping transistor also possesses the capacity to emulate typical synaptic characteristics at low energy levels (∼147 fJ). Leveraging the finely tunable conductivity through tribopotential, we demonstrate a mechano-assisted artificial neural network capable of recognizing handwritten digits with an accuracy rate of approximately 88.59%. These findings underscore the significant potential of the triboelectric charge-trapping transistor in mechanical-assisted real-time interaction, energy-efficient data storage, and neuromorphic computing. [Display omitted] • We propose a mechano-driven logic-in-memory based on neuromorphic triboelectric charge-trapping MoTe 2 transistor. • Gating by triboelectric potential, the neuromorphic device exhibits excellent electrical performance. • A mechano-assisted artificial neural network is demonstrated to recognize handwritten digits. [ABSTRACT FROM AUTHOR]

As pillars of the fourth industrial revolution, portable electronic devices and the Internet of Things are rapidly expanding. A sustainable energy supply for these devices is crucial to the sustainability of this network. It has been less than two decades since a triboelectric nanogenerator (TENG) was first introduced as a sustainable solution, and the development of these devices is accelerating rapidly. Material, structure, application, and performance optimization of these devices are all studied. The introduction of the MXene family in recent years has led to the development of TENG devices using these 2D materials. Various types of MXene behavior have been reported due to its diversity and customization, as well as its structural features caused by its 2D structure. These advantages have led MXene to its use as electrodes, electron trappers, and friction layers in TENG devices, both independently and as a complex. This article reviews studies on MXene-based TENG devices. The first part examines studies around three axes: MXene type, fabrication method, and application. The second section ranks and compares the performance parameters of these studies, and the third section provides details on the studies conducted. Finally, gaps and research opportunities in this field are highlighted, providing guidance for the future research. [Display omitted] • Reviews research directions on MXene-based triboelectric nanogenerators. • Analysis performance of different MXene-based TENG configurations and compositions. • Highlights open questions and future opportunities for MXene-based TENGs. [ABSTRACT FROM AUTHOR]

After decades of development, flexible force sensors (FFS) with excellent performance have been widely used in health monitoring, sport detection, soft robotics, electronic skin, human-machine interface. Researchers have concentrated on new materials and sophisticated structures for better performance and few have reported on functionality. The functional flexible force sensors (F-FFSs) will greatly enhance their practicality and is what needs to be considered as FFSs move from the laboratory to daily life. This paper is the first to review the functionalities of FFSs and to describe them, such as harsh environment stability, waterproofing, electromagnetic shielding, self-healing and antibacterial function. F-FFS offers great marginal benefits and will be an important development direction in the future. Finally, some questions and perspectives on the application aspects of FFSs will also be presented. [Display omitted] • The mechanisms of four types of flexible sensors and the current research status are outlined. • The advantages and disadvantages of the four types of flexible sensors are summarized and analyzed. • The functionality of flexible sensors is comprehensively reviewed, and its development prospect is prospectively analyzed. • Several representative functionality were analyzed in depth. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis and characteristics of the pure MXene using freeze dry method. • MXene based piezo-resistive device for stress sensing. • MXene based tribo-electric device for TENG application. • MXene based self-powered electrical readout device. In present work, MXene based piezo-resistive stress sensor device is fabricated using a freeze-dry method. The device was tested to measure the mechanical stress, sensitivity, and triboelectric response by converting them into electrical signals as readout. With high electrical conductivity, mechanical flexibility, and piezo-resistive characteristics, MXene-based device offers novel sensing and triboelectric-related applications. This study showed an extensive characterization after fabricating the sensor using a simple and scalable process to ensure their performance in terms of sensitivity, stability, and repeatability. Using pure MXene layer as the core material, this paper pioneers an interesting investigation focusing on stress monitoring by piezoresistive stress sensor and triboelectric nanogenerator. [ABSTRACT FROM AUTHOR]

Triboelectrification has been a well-known phenomenon for a long time. Although there are numerous debates regarding the actual mechanism involved in this, there are few interesting works uncovering its unique signatures. In this work, triboelectrification of needle punched nonwoven structures has been explored from a few important perspectives. The effect of linear density of constituent fibre on the triboelectric charge generation ability of needle punched nonwoven structures has been investigated. Further, the influence of antistatic agent on the triboelectric charge generation has been enlightened. An attempt has also been made to correlate the structural parameters of nonwoven with its triboelectrification performance. This research work not only reveals the triboelectrification phenomenon of this fibrous structure but also it is a food for novel thoughts on triboelectric charge generation process. [Display omitted] • Effect of fibre fineness on triboelectrification of needle punched nonwovens is studied. • Influence of scouring treatment on triboelectrification of needle punched nonwovens is investigated in a systematic manner. • Applications associated with triboelectrification of needle punched nonwoven are demonstrated. [ABSTRACT FROM AUTHOR]

In an era marked by a growing demand for sustainable energy solutions and resilient disaster management systems, the convergence of innovative technologies holds the promise of addressing multifaceted challenges. This manuscript explores the multifunctional capabilities of the "smart maracas", a novel triboelectric nanogenerator (TENG) designed to harvest mechanical energy and simultaneously serve as an earthquake sensor. The smart maracas is a striking example of the potential of TENGs to harness mechanical motion for practical applications. The device converts mechanical energy into electrical power through meticulous engineering, opening avenues for self-sustaining power sources in various domains. The manuscript outlines the device's structural design, working principle, and real-time applications, spanning bio-mechanical energy harvesting, vibrational energy scavenging, rotational energy harvesting, and a unique sensing application for door monitoring. A pivotal aspect of this research revolves around the smart maracas' role as an earthquake sensor. Rigorous experiments were conducted to assess the device's responsiveness to simulated seismic forces. Notably, a linear relationship with an R² value of 0.9989 was established between the voltage generated by the smart maracas and seismic acceleration. This remarkable correlation underscores the device's precision and reliability in detecting seismic events, opening doors for cost-effective earthquake monitoring solutions. [Display omitted] • Reusing laboratory falcon tube wastes for sustainable energy and sensing technology. • Plasma ion etching on PTFE balls and Hot water treatment on aluminum enhanced device performance. • SM-TENG Integrates artistry, engineering, energy generation, recycling, and disaster management. • Real-time applications in bio-mechanical, vibrational, and rotational energy harvesting. • SM-TENG expands functionality to door security, multi-directional vibration, and seismic sensing applications. [ABSTRACT FROM AUTHOR]

Mechanical energy harvesting technology converting mechanical energy wasted in our surroundings to electrical energy has been regarded as one of the critical technologies for self-powered sensor network and Internet of Things (IoT). Although triboelectric energy harvesters based on contact electrification have attracted considerable attention due to their various advantages compared to other technologies, a further improvement of the output performance is still required for practical applications in next-generation IoT devices. In recent years, numerous studies have been carried out to enhance the output power of triboelectric energy harvesters. The previous research approaches for enhancing the triboelectric charges can be classified into three categories: i) materials type, ii) device structure, and iii) surface modification. In this review article, we focus on various mechanisms and methods through the surface modification beyond the limitations of structural parameters and materials, such as surficial texturing/patterning, functionalization, dielectric engineering, surface charge doping and 2D material processing. This perspective study is a cornerstone for establishing next-generation energy applications consisting of triboelectric energy harvesters from portable devices to power industries.

Abstract The present work describes the hybridization of two different energy harvesters works simultaneously in a single package. By applying simultaneous mechanical force, two components such as triboelectric nanogenerator (TENG) and electromagnetic generator (EMG) independently produce power. The hybrid device was made with a polymeric cylinder composed of Kapton in the inner wall; a copper coil wound outside the cylinder and neodymium magnet and small bits of paper housed inside it. The paper flakes having the dimension of 5 mm × 5 mm, which are triboelectric positive slides over the negative triboelectric layer Kapton. The potential difference between the two different triboelectric material leads to the generation of electric power. The triboelectric component generates the maximum output with the voltage of ≈ 20 V and the current of 300 nA. The magnet inside the cylinder moves simultaneously along with the paper made the production of electric flux in the coil. The alternating magnetic flux induces the current in the outer coil as per the Lenz’s law. The maximum output generated from the EMG component with the obtained voltage of 2 V and the maximum current of 10 mA. Further, to analyze the actual working behavior of the device, commercial capacitor charging behavior was analyzed. The TENG component runs the consistent charging behavior, whereas the EMG component offers a rapid charging behavior, under hybrid mode both the merits can be utilized. The device has had placed in a backpack, and the biomechanical energy from human motions such as walking, running and jumping had been demonstrated. This study confirms that the proposed hybrid generator is capable of powering small electronic devices such as global positioning system (GPS), flashlights and potentially be able to use as an active MEMS/NEMS-based self-powered sensor.

This paper provides a technical analysis of energy harvesting (EH) in the field of power and energy sector, including different aspects of harvesting energy, individual case history, control strategies of harvesting in the field of power and energy sector together with the current trend and future aspects of it. EH is comparatively a new concept which is growing very fast since the 20th century and catching new generation research approaches. This paper not only describes the past and current scenarios of harvesting energy with radio frequency (RF) and renewables but also gives author’s own anticipation of the upcoming future trends of it by comparing the case histories.

Wearable technology represents a new technological paradigm for promoting physical activity, enabling monitoring of performances and athletic gestures. In addition, they can be employed for remote health monitoring applications, allowing continuous acquisition of users’ vital signs directly at home, emergency alerting, and computer-assisted rehabilitation. Commonly, these devices depend on batteries which are not the better option since researchers aim for dispositive who need minimal human intervention. Energy harvesting devices can be useful to extract energy from the human body, especially by integrating them into the garments, giving health monitoring devices enough energy for their independent operation. This review work focuses on the main new wearable technologies and devices to scavenge energy from the human body. First, the most suitable energy sources exploitable for wearable applications are investigated. Afterward, an overview of the main harvesting technologies (piezoelectric, triboelectric, thermoelectric, solar fabrics, and hybrid solution) is presented. In detail, we focused on flexible and thin textiles with energy harvesting capability, allowing easy integration into clothes fabric. Furthermore, comparative analyses of each harvesting technology are proposed, providing useful insights related to the best technologies for developing future self-sustainable wearable devices. Finally, a comparison between our review work and similar ones is introduced, highlighting its strengths in completeness and specificity.

Abstract Rapid advancements of artificial intelligence of things (AIoT) technology pave the way for developing a digital‐twin‐based remote interactive system for advanced robotic‐enabled industrial automation and virtual shopping. The embedded multifunctional perception system is urged for better interaction and user experience. To realize such a system, a smart soft robotic manipulator is presented that consists of a triboelectric nanogenerator tactile (T‐TENG) and length (L‐TENG) sensor, as well as a poly(vinylidene fluoride) (PVDF) pyroelectric temperature sensor. With the aid of machine learning (ML) for data processing, the fusion of the T‐TENG and L‐TENG sensors can realize the automatic recognition of the grasped objects with the accuracy of 97.143% for 28 different shapes of objects, while the temperature distribution can also be obtained through the pyroelectric sensor. By leveraging the IoT and artificial intelligence (AI) analytics, a digital‐twin‐based virtual shop is successfully implemented to provide the users with real‐time feedback about the details of the product. In general, by offering a more immersive experience in human–machine interactions, the proposed remote interactive system shows the great potential of being the advanced human–machine interface for the applications of the unmanned working space.

Abstract In the dawn of energy crisis and rising challenges in powering distributed low energy portable devices, nanogenerators, a class of mechanical energy harvesters is gaining increasing interest in fundamental research and commercial applications. Nanogenerators harvest energy by transducing mechanical energy into electric energy, the performance is highly related to the mechanical and electrical properties of the materials and devices. A typical nanogenerator consists of a substrate, a functional triboelectric active layer, electrode, and separator, which overall built‐up a three dimensional (3D) structure. 3D printing with its ability to form complex 3D structures possess coveted advantages in the development of nanogenerators. In this review, we introduce the importance of 3D structures for nanogenerators and explicitly discuss the different 3D printing methods and the ink formulation to tackle the challenges in 3D structured nanogenerators. Additionally, the principle and application of 4D printing in nanogenerator fabrication are critically highlighted.

Rapid advancements of artificial intelligence of things (AIoT) technology pave the way for developing a digital‐twin‐based remote interactive system for advanced robotic‐enabled industrial automation and virtual shopping. The embedded multifunctional perception system is urged for better interaction and user experience. To realize such a system, a smart soft robotic manipulator is presented that consists of a triboelectric nanogenerator tactile (T‐TENG) and length (L‐TENG) sensor, as well as a poly(vinylidene fluoride) (PVDF) pyroelectric temperature sensor. With the aid of machine learning (ML) for data processing, the fusion of the T‐TENG and L‐TENG sensors can realize the automatic recognition of the grasped objects with the accuracy of 97.143% for 28 different shapes of objects, while the temperature distribution can also be obtained through the pyroelectric sensor. By leveraging the IoT and artificial intelligence (AI) analytics, a digital‐twin‐based virtual shop is successfully implemented to provide the users with real‐time feedback about the details of the product. In general, by offering a more immersive experience in human–machine interactions, the proposed remote interactive system shows the great potential of being the advanced human–machine interface for the applications of the unmanned working space. [ABSTRACT FROM AUTHOR]

Summary: With the growing demand for wearable electronic devices, triboelectric nanogenerators (TENGs) provide an effective solution by harvesting human body motions and converting them into electricity. Tribomaterial is one key element for the output performance and application of TENGs. In this study, biomaterial eggshell membrane (ESM) was investigated for use as a piezoelectric‐enhanced positive tribomaterial. ESM not only exhibits excellent piezoelectricity due to the amount of hydrogen bonds, but it is also biocompatible and pollution free. The piezoelectricities of raw eggshell membrane (RESM), heated eggshell membrane (HESM), and carbonized eggshell membrane (CESM) were analyzed and compared. Porous expanded polytetrafluoroethylene (ePTFE) was fabricated and used as a negative tribomaterial in the TENG due to its strong electron‐acquisition ability. Pairing ESM with an ePTFE resulted in a novel piezoelectric‐enhanced triboelectric bio‐nanogenerator (P‐TENG) with an excellent energy harvesting ability, high‐efficiency output performance, and sensitive human motion monitoring. By comparing ePTFE paired with RESM, HESM, and CESM, the CESM/ePTFE P‐TENG showed the best output performance due to CESM's piezoelectric enhancement. This bio‐P‐TENG as a wearable electric device has great potential in biomedical applications. [ABSTRACT FROM AUTHOR]

The increasing interest in harvesting mechanical energy from day-to-day activities is gaining huge interest among researchers. We have fabricated a triboelectric nanogenerator (TENG) made of aluminum and PDMS film acting as positive and negative triboelectric layers. The layers are arranged in an arc-shaped structure with an air gap of 1 cm between the layers of the device. The PDMS layer is made by blending the polymer solution with the hardener in an appropriate ratio and dried to make the transparent and flexible polymer film. The device shows a maximum electrical response of 110 V and 260 nA voltage and current with the power density of 2.9 mW/m2 at 100 MΩ load resistance. Further, the device has been used for lighting green LEDs and charging commercial capacitors. An Arduino board was connected with LED and buzzer, which was triggered by the TENG device. This shows that with the proper usage of electronic components TENG can be used for self-powered sensors and with IoT applications. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerator (TENG) development is undergoing rapid progress utilizing the state‐of‐the‐art 3D‐printing technologies. Herein a critical analysis of the latest developments in 3D‐printed wearable and implantable TENGs that can be used to energize small portable electronic and biomedical devices is presented. Recent progress in 3D‐printed triboelectric nanogenerator (3DP‐TENG) materials and architectural formations, as well as their performance, is evaluated for powering systems that implement physiological monitoring, multifunctional sensing, electronic energizing, noise canceling, dust filtering, and self‐healing. Furthermore, the review explicitly focuses on the 3D‐printing approaches used to form stable and robust 3DP‐TENGs. In addition, the key challenges to improving the performance of 3DP‐TENGs for optimal energy harvesting are discussed, and a roadmap is given for research and translation to commercial markets in the next decade.

Since 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. [ABSTRACT FROM AUTHOR]

Energy harvesting devices based on the triboelectric effect have attracted great attention because of their higher output performance compared to other nanogenerators, which have been utilized in various wearable applications. Based on the working mechanism, the triboelectric performance is mainly proportional to the surface charge density of the triboelectric materials. Various approaches, such as modification of the surface functional group and dielectric composition of the triboelectric materials, have been employed to enhance the surface charge density, leading to improvements in triboelectric performances. Notably, tuning the dielectric properties of triboelectric materials can significantly increase the surface charge density because the surface charge is proportional to the relative permittivity of the triboelectric material. The relative dielectric constant is modified by dielectric polarization, such as electronic, vibrational (or atomic), orientation (or dipolar), ionic, and interfacial polarization. Therefore, such polarization represents a critical factor toward improving the dielectric constant and consequent triboelectric performance. In this review, we summarize the recent insights on the improvement of triboelectric performance via enhanced dielectric polarization. [ABSTRACT FROM AUTHOR]

• 3D-printed titanium device integrates triboelectric generators into knee prosthesis. • Stiffness of 3D printed prototype less than predicted value in finite element model. • Fatigue failure occurred prematurely during simulated gait loading. • Triboelectric generators embedded in device were able to generate sufficient power. • Stiffness and fatigue strength affected by internal porosity and surface roughness. Instrumented implants have the potential to detect abnormal loading patterns which could be deleterious to implant longevity, indicating a need for intervention which could reduce the need for more complicated revision surgeries. Reliably powering such devices has been one obstacle preventing widespread usage of instrumented implants in clinical populations. This study presents a 3D-printed titanium interpositional device designed to integrate triboelectric generators (TEGs) into a commercially available total knee replacement (TKR). The device's stiffness, durability, and efficacy as a TEG housing were determined. Surprisingly, the stiffness of the 3D printed prototype was 73% less than what was calculated in a corresponding computational model, and under long-term durability testing failed after approximately 30,000 cycles of simulated gait loading. Under cyclical compressive loading, TEGs embedded in the device were able to generate 10.05 μW of power which is sufficient to run the frontend electronics for a load measurement system. The stiffness discrepancy between the computational and experimental models and the premature fatigue failure are suspected to be a result of internal porosity, unfused material and surface roughness of the 3D printed metal. Further refinements in design and manufacturing of the compliant device are required to improve its durability and TEG power output. [ABSTRACT FROM AUTHOR]