Self-powered Motion Research Articles

A Self-powered Kinetic Motion Sensor Fabricated from Electrospun MOF-5/PVDF-TrFE Composites Piezoelectric Nanogenerators

A Self-powered Kinetic Motion Sensor Fabricated from Electrospun MOF-5/PVDF-TrFE Composites Piezoelectric Nanogenerators

Metal coordination bond and rough interface enhanced triboelectric nanogenerator aiming for multiple complex conditions

Triboelectric nanogenerator (TENG) is widely used in the fields of sustainable green energy harvesting, self-powered motion parameter and tactile sensing, However, it still fails to meet the requirements under various complex conditions, such as low temperatures, self healing after destruction, punching, long-term placement, soaking in acid or alkali solution, scorch, continuous work. Herein, based on metal coordination, Zr4+ ions are introduced to enhance the first network k-carrageenan (k-CG) for achieving double enhancement in mechanics and electricity of the gel electrode layer, poly (N-hydroxyl acrylamide)/k-CG (PKZ) double network organic conductive gel enhanced by multiple hydrogen bonds and metal coordination bond is designed, and the gel exhibits high tensile strength, high conductivity, fast self-recovery, excellent self-repairing and low-temperature resistance. Based on simple sandpaper templates with different mesh numbers Ecoflex film with rough surfaces is designed for efficient triboelectric contact interface, and TENG with PKZ double network organic conductive gel as electrode layer is constructed, and possesses excellent resistant to multiple complex conditions. With high short-circuit current, open-circuit voltage and output power, the TENG is capable of powering electronic devices, and it can also be sensitive and stable sensing in writing recognition, real-time monitoring of motion parameters involving acceleration, speed and distance. The TENG is stable and reliable for sustainable green energy harvesting, motion parameter and tactile sensing in multiple complex environments. Thus, we provide novel ideas for designing energy harvesting and sensing for future wearable electronics under multiple complex conditions.

MXene Hybridized Polymer with Enhanced Electromagnetic Energy Harvest for Sensitized Microwave Actuation and Self-Powered Motion Sensing

HighlightsAn alternative electromagnetic attenuation pathway is proposed in the MXene-polymer hybrid structure, distinct from conduction loss, for generalizing the results to a wider range of electromagnetic-thermal driven soft materials and devices.By efficiently harvesting and converting electromagnetic energy, the response time of the hybrid polymer to microwave exhibits 87% reduction with merely 0.15 wt% MXene.A new mode of self-powered motion sensing based on deformation-driven piezoelectric effect is developed, enhancing the material’s intelligence.

A hybrid triboelectric-piezoelectric-electromagnetic generator with the high output performance for vibration energy harvesting of high-speed railway vehicles

With the rapid development of intelligent high-speed train, people's travel becomes more convenient, time-saving and comfortable. However, the increase in the number of equipped electronic facilities also brings more power consumption. While the ultra-high voltage drive power system cannot directly drive its numerous devices and the vibrational energy of high-speed trains is completely abandoned. Herein, a hybrid triboelectric-piezoelectric-electromagnetic generator (HTG) is proposed to drive the signal and sensing devices of high-speed train by in-situ harvesting the corresponding vibration energy. Compared with commercial polyformaldehyde film, the output power of triboelectric nanogenerator with the polyformaldehyde nanofiber film prepared by electrospinning technology is improved by 130 times. Furthermore, thanks to the high space utilization and output performance, the HTG has achieved a power-density of the order of kW/m3, which is an improvement of 1–3 orders of magnitude compared to previous research work on vibration energy collection. Importantly, the self-powered wireless motion monitoring system based on HTG can realize real-time monitoring and transmission of motion information such as speed, frequency and displacement. This finding not only gives an important way to efficiently harvest vibration energy, but also provides new ideas for the design of more economical, comfortable and intelligent high-speed trains.

Piezoelectric-electromagnetic wearable harvester for energy harvesting and motion monitoring

This paper proposes a piezoelectric-electromagnetic wearable harvester (PEWH). The device is used to harvest the energy generated when the upper limb swings and can perform the function of motion monitoring. The main structure of PEWH consists of the piezoelectric power generation module and electromagnetic sensing module. Among them, the piezoelectric sheet in the piezoelectric module deforms and outputs electric energy, and the magnetic ball in the electromagnetic module moves to generate induced electromotive force to achieve sensing and energy supply. Through experimental testing, PEWH output performance is optimal when the spring wire diameter is 0.8 mm and the distance between the spring connector where the spring located and the position of the top of the shaft is 65 mm. At a vibration excitation frequency of 2 Hz, the device’s output voltage reaches a peak-to-peak value of 57.84Vpp, accompanied by a maximum power of 115.52mW. A range of application experiments were conducted to confirm the output performance of the device, which can power 82 LEDs and the temperature and humidity sensor. The prototype can be worn on the arm to enable monitoring of the current movement status. PEWH can effectively capture the energy generated by human movement for self-powered and self-sensing motion detection.

Bio-inspired e-skin with integrated antifouling and comfortable wearing for self-powered motion monitoring and ultra-long-range human-machine interaction

Electronic skin (e-skin) inspired by the sensory function of the skin demonstrates broad application prospects in health, medicine, and human–machine interaction. Herein, we developed a self-powered all-fiber bio-inspired e-skin (AFBI E-skin) that integrated functions of antifouling, antibacterial, biocompatibility and breathability. AFBI E-skin was composed of three layers of electrospun nanofibrous films. The superhydrophobic outer layer Poly(vinylidene fluoride)-silica nanofibrous films (PVDF-SiO2 NFs) possessed antifouling properties against common liquids in daily life and resisted bacterial adhesion. The polyaniline nanofibrous films (PANI NFs) were used as the electrode layer, and it had strong “static” antibacterial capability. Meanwhile, the inner layer Polylactic acid nanofibrous films (PLA NFs) served as a biocompatible substrate. Based on the triboelectric nanogenerator principle, AFBI E-skin not only enabled self-powered sensing but also utilized the generated electrical stimulation for “dynamic” antibacterial. The “dynamic-static” synergistic antibacterial strategy greatly enhanced the antibacterial effect. AFBI E-skin could be used for self-powered motion monitoring to obtain a stable signal output even when water was splashed on its surface. Finally, based on AFBI E-skin, we constructed an ultra-long-range human-machine interaction control system, enabling synchronized hand gestures between human hand and robotic hand in any internet-covered area worldwide theoretically. AFBI E-skin exhibited vast application potential in fields like smart wearable electronics and intelligent robotics.

Multifunctional organohydrogels enabling sensitive strain sensing and self-powered triboelectricity

Hydrogels have broad application prospects in portable strain sensors and triboelectric nanogenerators (TENG), and have attracted great attention in the field of wearable electronic devices and energy transfer devices. However, the development of multifunctional gels that can meet a variety of application scenarios is still a challenging problem. In this study, a multifunctional poly(acrylamide-co-2-acrylamide-2-methylpropanesulfonic acid)/lignosulfonate/Zr4+ organohydrogel noted as “P(AM-co-AMPS)/LS/Zr4+” was fabricated based on dynamic metal coordination bonds and hydrogen bonds, which could be used as flexible strain sensor and TENG electrode material. The organohydrogel based strain sensor could monitor both large and tiny human movements due to the high sensitivity (GF = 4.37, up to 200 %) and circulation stability. The assembled organohydrogel-based triboelectric nanogenerator (O-TENG) could generate an open-circuit voltage of 70.47 V and a short-circuit current of 25.21 μA. It is worth mentioning that the O-TENG could light up 44 LED bulbs by tapping with the palm at −20 °C, and the electronic output performance of the O-TENG after self-healing was unaffected. Additionally, the O-TENG exhibited enormous potentials in the biomechanical energy harvesting and self-powered motion sensors in the areas of human movements detection, human–computer interaction, electronic skin and self-powered devices.

Graphene-Doped Thermoplastic Polyurethane Nanocomposite Film-Based Triboelectric Nanogenerator for Self-Powered Sport Sensor.

Triboelectric nanogenerators (TENGs), as novel electronic devices for converting mechanical energy into electrical energy, are better suited as signal-testing sensors or as components within larger wearable Internet of Things (IoT) or Artificial Intelligence (AI) systems, where they handle small-device power supply and signal acquisition. Consequently, TENGs hold promising applications in self-powered sensor technology. As global energy supplies become increasingly tight, research into self-powered sensors has become critical. This study presents a self-powered sport sensor system utilizing a triboelectric nanogenerator (TENG), which incorporates a thermoplastic polyurethane (TPU) film doped with graphene and polytetrafluoroethylene (PTFE) as friction materials. The graphene-doped TPU nanocomposite film-based TENG (GT-TENG) demonstrates excellent working durability. Furthermore, the GT-TENG not only consistently powers an LED but also supplies energy to a sports timer and an electronic watch. It serves additionally as a self-powered sensor for monitoring human movement. The design of this self-powered motion sensor system effectively harnesses human kinetic energy, integrating it seamlessly with sport sensing capabilities.

Recent Advances in Wearable Textile-Based Triboelectric Nanogenerators.

We review recent results on textile triboelectric nanogenerators (T-TENGs), which function both as harvesters of mechanical energy and self-powered motion sensors. T-TENGs can be flexible, breathable, and lightweight. With a combination of traditional and novel manufacturing methods, including nanofibers, T-TENGs can deliver promising power output. We review the evolution of T-TENG device structures based on various textile material configurations and fabrication methods, along with demonstrations of self-powered systems. We also provide a detailed analysis of different textile materials and approaches used to enhance output. Additionally, we discuss integration capabilities with supercapacitors and potential applications across various fields such as health monitoring, human activity monitoring, human-machine interaction applications, etc. This review concludes by addressing the challenges and key research questions that remain for developing viable T-TENG technology.

Wearable self-powered motion sensor based on biomass carbon-dots/polyvinyl alcohol film

The functionalized polymer with scalable properties presents a promising option for flexible triboelectric nanogenerators designed for detecting human motion. In this study, a novel method to fabricate tribopositive composite film was proposed by incorporating high permittivity N-doped orange peel-based carbon dots (O-CDs) into the highly cross-linked polyvinyl alcohol (PVA). The O-CDs/PVA sensor showed elevated electrical output with the raised content of O-CDs until 1.5 wt. % with a peak voltage of 3.5 V. The response characteristics under various external force conditions were tested, and the maximum peak voltage and current reached 3.92 V and 28.6 A under the force of 50 N. Moreover, O-CDs/PVA sensors present superior high-output stability, durability, and accurate distinction to different movement states, even the vocal cord vibration. By introducing the support vector machine learning algorithm, intelligent gesture recognition was achieved. This work paves a facile, feasible, and scalable pathway to the self-powered human motion sensor device.

Highly Moisture-Resistant Flexible Thin-Film-Based Triboelectric Nanogenerator for Environmental Energy Harvesting and Self-Powered Tactile Sensing.

Triboelectric nanogenerator (TENG) has been demonstrated as a sustainable energy utilization method for waste mechanical energy and self-powered system. However, the charge dissipation of frictional layer materials in a humid environment severely limits their stable energy supply. In this work, a new method is reported for preparing polymer film as a hydrophobic negative friction material by solution blending poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and polyvinyl chloride (PVC), doping with titanium dioxide (TiO2) nanoparticles, and further surface patterning modification. The P-TENG composed of the PVDF-HFP/PVC/TiO2 composite film with optimized hydrophobic performance (WCA = 124°) achieved an output voltage of 235 V and a short-circuit current of 35 μA, which is approximately three times that of the bare PVDF-HFP-based TENG. Under charge excitation, the transferred charge of the P-TENG can reach 35 nC. When the external load resistance is 5.5 MΩ, the output peak power density can reach 1.4 W m-2. Meanwhile, the hydrophobic surface layer with a rough surface structure enables the device to overcome the influence of water molecules on charge transfer in a humid environment, quickly recover, and maintain a high output. The P-TENG can effectively monitor finger flexibility and strength and realize real-time evaluation of the exercise state and hand fatigue of the elderly and rehabilitation trainers. It has broad application prospects in self-powered intelligent motion sensing, soft robotics, human-machine interaction, and other fields.

Application of triboelectric nanogenerator in self-powered motion detection devices: A review

Among today’s bustling lifestyles, the demand for autonomous, durable, and low-maintenance healthcare systems has surged, surpassing that of earlier periods. Nanostructured and environmentally friendly materials employed in nanogenerator technology offer a novel avenue for biomedical applications by harnessing biomechanical energy. Triboelectric Nanogenerators (TENGs) have emerged as comprehensive solutions, furnishing self-sustaining, eco-conscious, and compact devices. Recognizing the immense potential of TENGs, this paper presents a comprehensive overview of its motion detection. Our analysis delves into the versatility of TENG-based motion detection systems, providing wearable, user-friendly solutions powered by human motion. Recent advancements in triboelectric devices are cataloged, elucidating their structural intricacies, capabilities, performance metrics, and future prospects. In addition, the article also outlines the applications of different TENGs in motion monitoring, including contact, non-contact, and single-electrode mode. The evolution of intelligent wearable technologies has extended our capacities in communication, healthcare, and various other domains beyond our biological limits. Apart from the Internet of Things, the concept of Internet of bodies or beings is poised for rapid advancement, promising further transformation of our lifestyles. Conclusively, we present insights into forthcoming opportunities and plausible strategies to address anticipated hurdles.

Synergistic effect of microscopic buckle and macroscopic coil for self-powered organ motion sensor

Although soft mechano-electrochemical energy harvesters have attracted considerable attention as wearable sensors, they face challenges, including low output performance, high Young’s modulus and low energy-conversion efficiency. To address these limitations, we introduce a novel design featuring macroscopically coiled and microscopically buckled fibres to improve the mechano-electrochemical energy-harvesting capability, thereby maximising capacitance change and affording higher electrical output. The harvester achieved a gravimetric peak current density of 121 A/kg and a peak power density of 16 W/kg. Moreover, the harvester showed enhanced stretchability under a strain of over 400 %, low Young’s modulus of 0.2 MPa and an energy conversion efficiency of 0.33 %. Furthermore, when implanted in a pig’s bladder, it showed minimal impact during expansion and contraction thanks to its softness and provided real-time electrical output in response to static and dynamic volume changes.

Free-standing graphene oxide/carboxymethyl cellulose paper-based triboelectric nanogenerator for self-powered motion sensor

Triboelectric nanogenerators (TENG) are innovative energy-harnessing devices that serve as potential power sources for small portable electronics, operating on the principle of electrostatic induction. In this study, we demonstrate the fabrication of paper-like flexible graphene oxide/carboxymethyl cellulose (GO/CMC) composite film and their use as a tribo-positive layer in the TENG with fluorinated ethylene propylene (FEP) film as the tribo-negative layer. The GO/CMC TENG possesses high-energy harvesting performance compared to the bare CMC-based TENG that is due to the increase in surface charge of CMC due to the inclusion of GO sheets, as analyzed using Kelvin probe force microscopy (KPFM). The GO/CMC TENG device demonstrates an output voltage of 97 V and a short-circuit current of 1.2 µA, achieving a peak power of 41.4 µW, notably higher compared to state-of-the-art TENG devices. As a proof-of-concept, we also demonstrated the practical applicability of the GO/CMC TENG in day-to-day life for monitoring the human body motions and to drive portable electric devices, which ensures their candidature towards next-generation self-powered systems.

Self-Powered Hybrid Motion and Health Sensing System Based on Triboelectric Nanogenerators.

Triboelectric nanogenerator (TENG) represents an effective approach for the conversion of mechanical energy into electrical energy and has been explored to combine multiple technologies in past years. Self-powered sensors are not only free from the constraints of mechanical energy in the environment but also capable of efficiently harvesting ambient energy to sustain continuous operation. In this review, the remarkable development of TENG-based human body sensing achieved in recent years is presented, with a specific focus on human health sensing solutions, such as body motion and physiological signal detection. The movements originating from different parts of the body, such as body, touch, sound, and eyes, are systematically classified, and a thorough review of sensor structures and materials is conducted. Physiological signal sensors are categorized into non-implantable and implantable biomedical sensors for discussion. Suggestions for future applications of TENG-based biomedical sensors are also indicated, highlighting the associated challenges.

A molybdenum-disulfide nanocomposite film-based stretchable triboelectric nanogenerator for wearable biomechanical energy harvesting and self-powered human motion monitoring

Triboelectric nanogenerators (TENGs) are receiving significant interest in the wearable electronics industry owing to their distinct ability to capture ambient energy, particularly from human endeavors. Because they can serve as renewable sources of energy and multifunctional sensing devices. Herein, a stretchable TENG (S-TENG) based on micropatterned fabric-coated molybdenum disulfide (MoS2) and an Ecoflex nanocomposite as the electron-acceptor layer is newly developed for harvesting biomechanical energy to power wearable electronics and enable self-powered sensing. Incorporating the MoS2 monolayer in the composite creates microchannels on the surfaces, improving the conductivity of the composite by facilitating ion transport. Moreover, the incorporation of the monolayer provides an additional triboelectric output by increasing the contact area, enhancing the dielectric constant, and modulating the surface charge density. The use of knitted fabric materials enhances the extensibility (230 %) of the composite film. A thorough investigation was conducted to assess the electric output performance, resulting in the attainment of a maximum peak power density of 11 W/m2. This power density is sufficient to provide electricity to a typical electronic equipment with low power consumption. Regarding passive sensing, the suggested S-TENG may be used as a pressure sensor, with a high sensitivity of 17.18 V/kPa. Furthermore, active sensing enables the identification of dynamic movements in the joints of the human body by establishing a relation between gestures and the corresponding electrical signals. This study presents an innovative approach for developing a wearable S-TENG that exhibits dual-mode energy-harvesting and sensing capabilities, including the use in biomedical applications and human-machine systems.

Active self-powered human motion assist system

Harvesting human energy currently occurs to power wearable devices or monitor human signs, these applications make the energy harvester less applicable to and seldom used for assisting human motion. However, there is a high demand for using such collected energy with the assistance of human motion. This paper presents a novel energy harvester that is designed to collect negative work, assist human motion, and realize self-powering. An active self-powered human motion assist system (HMAS) is developed. The system consists of a human motion assist device, a flexible rack, an electronic circuit module, and a supercapacitor. The HMAS can collect negative work from the human body, provide the user with additional motion assistance, and reduce stamina consumption. A series of experiments verify that HMAS has a high negative work collection power and a high energy conversion efficiency. The average output power is 0.93 W measured by the negative work collection test bed at a simulated knee bend angle of 40° and a frequency of 2 Hz. The energy conversion efficiency is up to 48.2%. Human motion assistance experiments verify that HMAS can provide volunteers with up to 2.57% assisting moment and minimize the metabolic cost of volunteers by 6.07% compared to without wearing HMAS. This research work is proposed to contribute to the development of active self-powered exoskeleton technology. This technology can be practically applied in the fields of rehabilitation therapy, logistics transportation, and military combat.

Biodegradable and flame-retardant cellulose-based wearable triboelectric nanogenerator for mechanical energy harvesting in firefighting clothing

Integrating flexible triboelectric nanogenerators (TENGs) into firefighting clothing offers exciting opportunities for wearable portable electronics in personal protective technology. However, it is still a grand challenge to produce eco-friendly TENGs from biodegradable and low-cost natural polymers for mechanical-energy harvesting and self-powered sensing. Herein, conductive polypyrrole (PPy) and natural chitosan (CS)/phytic acid (PA) tribonegative materials were employed onto the Lycra fabric (LC) in turn to assemble the biodegradable and flame-retardant single-electrode mode LC/PPy/CS/PA TENG (abbreviated as LPCP-TENG). The resultant LPCP-TENG exhibits truly wearable breathability (1378.6 mm/s), elasticity (breaking elongation 291 %), and shape adaptivity performance that can produce an open circuit voltage of 0.3 V with 2 N contact pressure at a working frequency of 5 Hz with a limiting oxygen index of 35.2 %. Furthermore, facile monitoring for human motion of firefighters on fireground is verified by LPCP-TENG when used as self-powered flexible tactile sensor. In addition, degradation experiments have shown that waste LPCP-TENG can be fully degraded in soil within 120 days. This work broadens the applicational range of wearable TENG to reduce the environmental effects of abandoned TENG, exhibiting prosperous applications prospects in the field of wearable power source and self-powered motion detection sensor for personal protection application on fireground.

Discrete ZnO p-n homojunction piezoelectric arrays for self-powered human motion monitoring

Zinc oxide (ZnO), as a typical piezoelectric semiconductor, has gained significant attention in the field of wearable electromechanical coupling. However, the presence of an intrinsic screening effect becomes a bottleneck in developing high-performance ZnO-based piezoelectric devices. To address this limitation, we propose the formation of p-n homojunction by La doping in ZnO nanorods (NRs) as well as discrete structural design to improve their electrical output and flexibility. The enhanced performance and the mechanism behind it are explored and revealed in terms of morphology, structure, built-in electric field, depletion layer width, and junction capacitance, respectively. Benefitting from the excellent electromechanical coupling performance of the developed devices, different human motions can be recognized and classified with the aid of machine learning. These findings provide a new insight into the impact of doping on the output performance of piezoelectric semiconductor devices, thus facilitating advancements in piezoelectric device design and application exploration.

Self-powered flexible piezoelectric motion sensor with spatially aligned InN nanowires

The power output of piezoelectric sensors based on nanowires (NWs) is governed by various factors, but largely depends on the alignment of the NWs. However, aligning the NWs has proved to be difficult. We successfully developed self-powered and flexible piezoelectric motion sensors (PMSs) with InN NWs as a response medium. The device performance was maximized by spatially controlling the alignment of the InN NWs by applying a magnetic field, which was the first step in the development of the NW-PMSs. The output voltage of the PMS with the InN NWs aligned along the bending direction was measured to be 3.05 V, which was a significant improvement of 2.44 times compared to that with randomly-distributed NWs. A systematic analysis of the extent to which the performance of the PMSs depend on the device parameters, such as the length of the NWs, bending frequency, operation time (up to 30 days), relative humidity, and bending cycle, indicates that the device performance is sufficient for real-life applications. For example, attachment of the self-powered PMSs to human joints such as the finger, wrist, elbow, and knee revealed that these motion sensors are highly effective, thereby indicating the possibility of detecting the various motions of the human body. The self-powered PMSs developed in this work are expected to contribute to rehabilitation, disease prevention, and human–machine interaction.