Biomechanical Energy Harvesting Research Articles

Evaluation Methodology of a Smart Clothing Biomechanical Energy Harvesting System for Mountain Rescuers.

The article presents a methodology developed for the evaluation of biomechanical energy harvesting systems that permits avoiding long-duration outdoor tests while providing realistic input signals and preserving uniform conditions across repeated tests. It consists of two stages: transducer output signal recording and power conversion and storage system measurements. The proposed approach was applied to assess the usefulness of a commercial electromagnetic transducer for supplying a Global Positioning System (GPS) receiver used as an active component of a smart clothing dedicated for mountain rescuers. Electrical power yield measurements have been presented together with ergonomic tests results. They all involved diverse physical activities performed by mountain rescuers that simulated their true operations, but were conducted in a training room for the sake of standardization. By providing reliable data on the transducer’s performance under realistic use conditions, the proposed evaluation procedure revealed that the true energy yield was much smaller not only with respect to the manufacturer’s assertions, but also substantially lower than what was expected based on an independent review which used unrealistic and non-uniform excitations. On the other hand, ergonomics ratings given by potential end users were very high, which demonstrates that the evaluated transducer can still be useful for supplying active cloth components with a lower power demand. The study also revealed that transducer location and orientation strongly affect its performance, which must be taken into account at the first stage of the evaluation procedure. Moreover, physical activity type and conditions (such as motion speed and ground tilt) influence the output power and should be carefully considered when composing a typical case scenario for the second stage.

Super-stretchable multi-sensing triboelectric nanogenerator based on liquid conductive composite

Abstract Stretchable triboelectric nanogenerators (TENGs) attract much attentions in the field of wearable electronics owing to their unique capabilities of ambient energy harvesting, especially from human activities, serving as sustainable power source as well as functional sensing device. The essential challenge of super-stretchable triboelectric nanogenerator (SS-TENG) is to overcome the non-stretchable drawback of conventional electrodes and endow them with remarkable extension capability. In this work, we developed a carbon nanotubes (CNT)-silicone rubber liquid composite with outstanding conductivity and fluidity, which provides an essential opportunity to realize a SS-TENG with the remarkable capability of 900% stretchable deformation. This newly developed SS-TENG successfully achieved the integration of bio-mechanical energy harvesting and multi-functional sensing. The electric output performance was comprehensively investigated and a maximum power density of 21.7 W/m2 was obtained, which is large enough to power common low-power-consumption electronic devices. As for passive sensing, the proposed SS-TENG can be utilized as a strain gauge with good sensitivity (gauge factor (GF) of 11.4) and low hysteresis (degree of hysteresis (DH) of 0.71%). Moreover, as for active sensing, the detection of dynamic motions of human body joints was realized due to the correlation between gesture and corresponding electrical signal. Eventually, a self-powered wearable keyboard based on SS-TENG arrays with outstanding conformability on curved surfaces was demonstrated, which reveals a promising potential of the proposed liquid conductive composite and the developed SS-TENG for self-powered wearable electronic applications, especially in the healthcare field.

Enhanced energy harvesting ability of polydimethylsiloxane-BaTiO3-based flexible piezoelectric nanogenerator for tactile imitation application

The development of wearable piezoelectric nanogenerator (PENG) has recently drawn extensive attention, especially in selecting lead-free piezoelectric materials with high piezoelectric coefficients. Barium Titanate (BTO) is a kind of environment-friendly piezoelectric ceramics. PENGs derived from BTO based piezo-fillers have recently attracted broad concern. However, the exploration of flexible electrodes and the application of wearable PENGs functioned with imitating tactile have usually been ignored in the pursuit of high output performance. Herein, The porous piezoelectric fillers composed of 0.82Ba(Ti0.89Sn0.11)O3-0.18(Ba0.7Ca0.3)TiO3 are prepared by a freeze-drying method, and then the polydimethylsiloxane (PDMS) is filled into the micropores of the piezoelectric ceramics, forming a distinctive 3D interconnected structure with evenly distributed inorganic piezoelectric materials. Both doping and structure modification can boost the output performance of the BTO-based PENG, from which the rational doping plays a major role in enhancing the electrical output in the current PENG system. To realize fully flexible piezoelectric nanogenerator (PENG), sliver nanowires network integrated with PDMS is adopted as the flexible electrodes, which was fabricated by the techniques combining vacuum filtration with subsequent dry transfer process. The PENG can deliver a maximum open-circuit voltage (VOC) of 39 V and short-circuit (ISC) current of 2.9 μA under a vertical force of 35 N at 2 Hz, with the maximum instantaneous power of 24.2 μW. Moreover, the device can effectively exhibit electric output signal whenever subjected to external pressing or bending stress. The output performance of the PENG at via vertical pressing stress is higher than that bending stress, which is also confirmed by COMSOL simulation. The PENG can not only be employed to harvest biomechanical energy such as digital joints movement, but also display a potential for a tactile perception. This work has established a deep association between lead-free ceramic and wearable imitated touch reception sensors by virtue of flexible PENG, which will paint a magnificent picture for flexible electronics.

Implantable Cardiac Kirigami-Inspired Lead-Based Energy Harvester Fabricated by Enhanced Piezoelectric Composite Film.

Harvesting biomechanical energy to power implantable electronics such as pacemakers has been attracting great attention in recent years because it replaces conventional batteries and provides a sustainable energy solution. However, current energy harvesting technologies that directly interact with internal organs often lack flexibility and conformability, and they usually require additional implantation surgeries that impose extra burden to patients. To address this issue, here a Kirigami inspired energy harvester, seamlessly incorporated into the pacemaker lead using piezoelectric composite films is reported, which not only possesses great flexibility but also requires no additional implantation surgeries. This lead-based device allows for harvesting energy from the complex motion of the lead caused by the expansion-contraction of the heart. The device's Kirigami pattern has been designed and optimized to attain greatly improved flexibility which is validated via finite element method (FEM) simulations, mechanical tensile tests, and energy output tests where the device shows a power output of 2.4µW. Finally, an in vivo test using a porcine model reveals that the device can be implanted into the heart straightforwardly and generates voltages up to ≈0.7V. This work offers a new strategy for designing flexible energy harvesters that power implantable electronics.

Recent Progress on Bio-mechanical Energy Harvesting System from the Human Body: Comprehensive Review

Energy harvesting is a powerful technique to produce clean and renewable energy with better infrastructure improvement. The exhaustive review of recent progress and development in bio-mechanical energy harvesting (BMEH) techniques from human body is discussed in this manuscript. The BMEH from the human body is categorized into three parts, namely, piezoelectric energy harvesting (PEEH), triboelectric energy harvesting (TEEH), and Electro-magnetic Energy harvesting (EMEH). Each energy harvesting system is discussed with working principles with mathematical equations; each energy harvesting progress is discussed with a few work demonstrations. The applications of each energy harvesting from the recent research work are addressed in detail. The summary of each energy harvester from the human body or motion with advantages, limitations, performance metrics, current methods, and implemented human body parts are highlighted with Tabulation. The critical challenges/issues with possible solutions are also discussed.

Piezoelectric nanogenerator based on flexible PDMS–BiMgFeCeO6 composites for sound detection and biomechanical energy harvesting

Piezoelectric nanogenerators are dependent on a piezoelectric material for the conversion of mechanical stress into useful electrical energy.

Flexible triboelectric nanogenerator based on polyester conductive cloth for biomechanical energy harvesting and self-powered sensors.

As a new nanotechnology of mechanical energy harvesting and self-powered sensing, triboelectric nanogenerators (TENGs) have been explored as a new path of using various low-frequency disordered mechanical energies in the surrounding environment to provide power and/or sensing. However, the research of TENGs that provide full flexibility and environmental friendliness is still limited. Herein, a flexible single-electrode TENG (S-TENG) based on polyester conductive cloth as the working electrode is developed to harvest human motion energy for powering light emitting diodes (LEDs) and portable electronics. The flat conductive cloth was wrapped in a flexible elastomer. Defatted cowhide was firstly selected as a friction positive charge material for TENGs. When the size of the fabricated S-TENG is 40 × 100 mm2, high output performance has been achieved and it can generate an open-circuit voltage of 534 V and a power density of 230 mW m-2 at an operation frequency of 3.0 Hz. After integrating with a rectifier, the S-TENG can power 240 LEDs, charge various capacitors, and drive an electronic watch or a calculator. Moreover, the S-TENG can harvest the biomechanical energy of wrist movement, hand tapping, and human walking. Meanwhile, the S-TENG as a self-powered sensor can be employed to monitor subtle signals of human physiological activities, such as finger motion, facial masseter activity, and diaphragmatic breathing. Additionally, the S-TENG can be attached to clothes (such as wool coats, polyamide sweaters) to harvest the energy of cuff movement. Therefore, this work provides new insights for clean power sources of skin-mounted electronics and promotes the development of a sustainable energy supply for wearable and portable electronics.

Flexible, Self-Poled and Ultra-Sensitive Lead-Free Piezocomposite Nanogenerator for Biomechanical Energy Harvesting

Flexible, Self-Poled and Ultra-Sensitive Lead-Free Piezocomposite Nanogenerator for Biomechanical Energy Harvesting

Hybrid PDMS-TiO2-stainless steel textiles for triboelectric nanogenerators

• Electrophoretic deposition is employed to prepare hybrid textiles for tTENGs. • The tTENG possesses V oc ~ 110 V, I sc ~ 30 μA, Q ~ 9nC and P ~ 1.05 W m −2 . • Real-time biomechanical energy harvesting is realized on the worn tTENG. • A wireless communication via infrared rays is achieved by the wearable tTENG. Electrophoretic deposition is employed to deposit flower-like TiO 2 (F-TiO 2 ) particles onto stainless steel textiles to obtain a Fe@F-TiO 2 /PDMS hybrid textile as the negative tribo-material. The electrophoresis process enables adjustable deposit amounts and three-dimensional and uniform deposits of flower TiO 2 . The textile triboelectric nanogenerators (tTENGs) fabricated from the Fe@F-TiO 2 /PDMS hybrid textile working in conjunction with cotton and silk exhibit excellent performances. The tTENG generates a voltage of 120 V, a current of 25 μA and an output power of 0.85 W m −2 with the cotton and 110 V, 30 μA and 1.05 W m −2 with the silk. The flower-like TiO 2 is significant for the high performance of the tTENG, being attributed to the tailored surface and improved permittivity. Wearable tTENGs exhibit good durability after 8,000 cycles and power 58 light emitting diodes. By utilizing the worn tTENG, real-time biomechanical energy harvesting is realized; furthermore, a wireless communication via infrared rays is achieved, confirmed by the successfully receiving of the wireless signal and lighting up of the indicator LED. This work demonstrates high-performance hybrid textiles prepared by electrophoretic deposition and tTENGs for applications in wearable real-time energy harvesters and wireless communication units.

Design of a Human Lower Limbs Exoskeleton for Biomechanical Energy Harvesting and Assist Walking

Powered exoskeletons are used to assist walking, but carrying a huge power supply system will bring inconvenience to humans. Passive exoskeletons lack control and accurate energy management. The muscles of the leg work periodically during walking. When the legs are swinging down after they are lifted to the highest point, it is gravity that works on the human body, and it does not require extra energy. Therefore, this article describes a wearable human lower limb energy harvesting and transmission exoskeleton (EHTE) to achieve biomechanical energy during walking; to achieve the energy harvest, management, and migration. The EHTE is mounted on the thigh and the flat spiral springs are used to create the energy from leg swings. The springs periodically store and release energy, to reduce the energy consumed by human muscles, improving walking efficiency. A prototype device is designed to evaluate its performance. The test shows that the EHTE can provide nearly 7 N force for the contralateral ankle joint. The results demonstrate that the EHTE can provide physical support for patients with lower limb dyskinesia and improve their mobility independently.

Modeling and design of V-shaped piezoelectric vibration energy harvester with stopper for low-frequency broadband and shock excitation

Broadband low-frequency vibration and shock energies are ubiquitous such as biomechanical motion, which can be harvested to power wearable electronics. This paper proposes a compact design of V-shaped piezoelectric vibration energy harvester (V-PVEH) with impact stopper. To demonstrate V-PVEH having high power density, Euler beam model is proposed for qualitative comparison between V-PVEH and cantilevered piezoelectric vibration energy harvester (C-PVEH). FEA model in COMSOL for V-PVEH structure design is proposed especially for the stress check. Modal analysis, two bimorphs connection style, tip mass thickness, and acceleration amplitude are discussed in the experimental vibration validation. A peak voltage of 11.5 V at a low resonant frequency of 12 Hz and a maximum power of 0.442 mW are shown in experiments under the excitation of 0.1 g. A lumped parameters model with nonlinearity analysis for impact induced broadband and shock input is discussed comprehensively. The stopper design in V-PVEH can not only limit the vibration amplitude and prevent overload, but also form broadband of 8−15 Hz and generate large voltage output of 5−19 V when impact occurs at an acceleration of 0.4 g. Except for resonating excitation, biomechanical shock energy harvesting with ultra-low frequency of 1 Hz is testified for wearable V-PVEH to charge a 10 μF capacitor to 10 V in 5 s by stamping feet. Above all, V-PVEH with stopper is believed to show good performance in broadband low-frequency vibration and biomechanical shock energy harvesting.

Recent Trend in Biomechanical Energy Harvesting

In this literature different biomechanical energy harvesters are reviewed. In the past years a lot of work reported on energy harvesting. Energy crisis is the main issue in front of human so it is essential to find new promising ways to fulfil the need of electricity. Wearable smart devices and small sensor require low electrical power so to power them biomechanical energy harvesters comes into picture. The innovative work done by the researchers in developing new biomechanical energy harvester is discussed and summarized.

Stretchable and Shape‐Adaptable Triboelectric Nanogenerator Based on Biocompatible Liquid Electrolyte for Biomechanical Energy Harvesting and Wearable Human–Machine Interaction

AbstractThe significant demand of sustainable power sources has been triggered by the development of wearable electronics (e.g., electronic skin, human health monitors, and intelligent robotics). However, tensile strain limitation and low conformability of existing power sources cannot match their development. Herein, a stretchable and shape‐adaptable liquid‐based single‐electrode triboelectric nanogenerator (LS‐TENG) based on potassium iodide and glycerol (KI‐Gly) liquid electrolyte as work electrode is developed for harvesting human motion energy to power wearable electronics. The LS‐TENG demonstrates high output performances (open‐circuit voltage of 300 V, short‐circuit current density of 17.5 mA m–2, and maximum output power of 2.0 W m–2) and maintains the stable output performances without deterioration under 250% tension stretching and after 10 000 cycles of repeated contact‐separation motion. Moreover, the LS‐TENG can harvest biomechanical energy, including arm shaking, human walking, and hand tapping, to power commercial electronics without extra power sources. The LS‐TENG attached on different joints of body enables to work as self‐powered human motion monitor. Furthermore, a flexible touch panel based on the LS‐TENG combined with a microcontroller is explored for human–machine interactions. Consequently, the stretchable and shape‐adaptable LS‐TENG based on KI‐Gly electrolyte would act as an exciting platform for biomechanical energy harvesting and wearable human–machine interaction.

A Fully Functional Universal Self‐Chargeable Power Module for Portable/Wearable Electronics and Self‐Powered IoT Applications

AbstractRealization of self‐charging, miniaturized, portable, high output, and sustainable energy harvesting devices with wide application areas and good storage under a realistic environment remains a challenge. Herein, a universal self‐chargeable power module (USPM) is presented that can efficiently harvest human bio‐mechanical energy, ocean wave blue energy, and automobile vibration energy. By implementing a multiple spring‐based mechanical coupling design, the hybrid electromagnetic‐triboelectric generator shows high performance despite miniaturization under very low acceleration (≤1 g) and low frequency (≤6 Hz) vibration. The electromagnetic performance is further optimized by using a soft magnetic material‐based flux concentrator while electrospun nanofibers enhance the triboelectric performance. The USPM is a compactly designed device including a power management circuit, a battery charging circuit, built‐in rechargeable storage, and a USB‐C outlet, providing a direct current power of maximum 34.11 mW. Experimental results show remarkable performance in the context of harvesting biomechanical energy from walking, running, cycling and demonstrates real‐time charging of smartphones, earbuds, and smart bands. Similarly, it demonstrates the capability of harvesting blue energy and powering a wireless water health monitoring system using a polyaniline/laser‐induced graphene/polydimethylsiloxane based pH sensor. Moreover, it successfully scavenges automobile vibration energy and demonstrates a self‐powered wireless in‐car environment monitoring system.

Breathable, washable and wearable woven-structured triboelectric nanogenerators utilizing electrospun nanofibers for biomechanical energy harvesting and self-powered sensing

With the rapid advancement in wearable electronics, energy harvesting devices based on triboelectric nanogenerators (TENGs) have been intensively investigated for providing sustainable power supply for them. However, the fabrication of wearable TENGs still remains great challenges, such as flexibility, breathability and washability. Here, a route to develop a new kind of woven-structured triboelectric nanogenerator (WS-TENG) with a facile, low-cost, and scalable electrospinning technique is reported. The WS-TENG is fabricated with commercial stainless-steel yarns wrapped by electrospun polyamide 66 nanofiber and poly(vinylidenefluoride-co-trifluoroethylene) nanofiber, respectively. Triggered by diversified friction materials under a working principle of freestanding mode, the open-circuit voltage, short-circuit current and maximum instantaneous power density from the WS-TENG can reach up to 166 V, 8.5 µA and 93 mW/m 2 , respectively. By virtue of high flexibility, desirable breathability, washability and excellent durability, the fabricated WS-TENG is demonstrated to be a reliable power textile to light up 58 light-emitting diodes (LED) connected serially, charge commercial capacitors and drive portable electronics. A smart glove with stitched WS-TENGs is made to detect finger motion in different circumstances. The work presents a new approach for self-powered textiles with potential applications in biomechanical energy harvesting, wearable electronics and human motion monitoring. A brand-new type of nanofiber-based triboelectric nanogenerator with simple woven-fabric structure, remarkable breathability and washability, diversified triggering materials and reliable durability was designed and realized by utilizing novel core-shell yarns composed of functional nanofiber coating layer and core electrode yarn by a versatile electrospinning and scalable weaving strategy for the first time, and its promising potentials for harvesting biomechanical energy and self-powered sensing applications were demonstrated. • A brand-new type of nanofiber-based TENG with woven fabric structure was prepared by an electrospinning and weaving strategy. • The obtained WS-TENGs possess remarkable air and moisture permeability, robust durability and good washability. • The WS-TENGs can be triggered by diverse frictional materials and influential factors on output performance were studied. • Fixed at different positions of human body, WS-TENGs show application potential for biomechanical energy harvesting. • A smart-glove with stitched WS-TENGs was fabricated to demonstrate the capacity for self-powered sensing application.

Dielectric and ferroelectric properties of PVDF thin film for biomechanical energy harvesting

Abstract The energy crisis has been global havoc due to increasing demand in energy sectors which further have a serious impact on declining fossil fuels. There is a quest to develop green alternative sources of energy such as biomass, geothermal, photovoltaics. The piezoelectric nanogenerator has also been a fascinating technology to harvest small level mechanical energy to an electrical output. The vibration energy from walking, rail/air vehicles, tires, sound waves are converted efficiently to usable energy. This report shows the fabrication of PVDF thin film using the solvent casting route. The various properties like structural, morphology, dielectric, piezoelectric, and ferroelectric are analyzed. Further, a piezoelectric nanogenerator was fabricated and results of poled and unpoled films have been investigated. The device output was utilized to light up a LED and charge a commercial capacitor.

Exo-shoe triboelectric nanogenerator: Toward high-performance wearable biomechanical energy harvester

Abstract Among various daily human motions, walking is considered the most natural and strongest one. In this study, the exo-shoe TENG (ES-TENG) with the rationally designed bi-directional gearbox is developed to generate extended and enhanced output performance during daily walking. This bi-directional gearbox effectively converts the whole stroke of a reciprocating and low frequency (1 Hz) natural stepping motion into uni-directional high-speed rotation (700 rpm). The proposed ES-TENG exhibits more than ten times enhancement of the output performance with effective motion transformation. Although the normal stepping motion is not interrupted by the ES-TENG, the specific power of the ES-TENG could reach up to 13 µW/g through a single daily stepping motion. Real-time self-powered environmental monitoring and charging wearable electronics are demonstrated as proof-of-concept applications. Furthermore, the voltage multiplier circuit is used to generate a boosted open-circuit voltage of more than 3 kV, which shows the potential electric treatment applications of the ES-TENG. The ES-TENG provides the potential of biomechanical energy harvesting with a broad range of applications through the generation of highly enhanced output performance under natural daily stepping motions.

Interface induced performance enhancement in flexible BaTiO3/PVDF-TrFE based piezoelectric nanogenerators

Nanocomposites consisting of a flexible piezoelectric polymer and a reinforcing phase have shown great potential for constructing high-performance piezoelectric nanogenerators (PENGs). However, the weak interface and poor dispersion of piezoelectric reinforcing phase significantly impair the electromechanical properties (e.g., effective stress/strain, piezoelectric coefficients) of the nanocomposites, thus severely restricting the performance enhancement of the PENGs. In this study, we hydrothermally synthesized the piezoelectric reinforcing phase of BaTiO3 nanowires, and grafted a layer of high-modulus polymethyl methacrylate (PMMA) onto the nanowire surface via surface-initiated polymerization. The PMMA coating layer forms a strong interface between BaTiO3 nanowires and the polymer matrix [i.e., poly(vinylidenefluoride-co-trifluoroethylene)], which efficiently improves dispersion of the BaTiO3 nanowires and stress transfer at the interface, therefore resulting in an enhanced output performance in the fibrous nanocomposite PENGs. The output voltage and current of the PMMA encapsulated BaTiO3 ([email protected]3) nanowires-based PENG can reach to 12.6 V and 1.30 μA, with a maximum output power of 4.25 μW, which is 2.2 times and 7.6 times higher than the PENG with unmodified BaTiO3 nanowires and the PENG without BaTiO3 nanowires, respectively. Furthermore, the flexible PENG exhibits great stability that could continuously generate stable electrical pulses for 6000 cycles without any decline. This study provides a feasible approach of interface tailoring for achieving high-performance piezoelectric nanocomposite and shows the promising potential of the fibrous nanocomposites in biomechanical energy harvesters and smart wearable sensors.

Smart Insole for Robust Wearable Biomechanical Energy Harvesting in Harsh Environments

Footfall contains the highest harvestable biomechanical energy from the human body, which can attain 67 W, showing great potential as a pervasive and sustainable power source for wearable bioelectronics in the era of the Internet of Things. Developing an effective technology for robust and efficient energy harvesting from human walking remains highly desired. Here, we present a waterproof smart insole, based on a triboelectric nanogenerator, for highly efficient and robust human biomechanical energy harvesting. This insole was rationally designed as a composite structure to fully utilize the pressure distribution of a footfall for wearable electricity generation and to deliver a power output reaching 580 μW. The insole was additionally able to withstand use in harsh environments, including pluvial conditions, without affecting the power output consistency. A total of 260 light-emitting diodes were lit up with perspiring feet and water on the floor, and a capacitor of 88 μF was charged to 2.5 V in 900 s. This work represents a practical approach to developing a highly efficient and robust smart insole that can be used as a sustainable power source for wearable bioelectronics.

Organogel electrode enables highly transparent and stretchable triboelectric nanogenerators of high power density for robust and reliable energy harvesting

Rapid advancements in stretchable and multifunctional next-generation electronics have raised great demand in development of transparent, stretchable and reliable power sources. Here, an organogel electrode, consisted of Poly(4-acryloylmorpholine) frame and low polarity propylene carbonate swelling solvent, was prepared for constructing a new kind of organogel ionic electrode based triboelectric nanogenerator (TENG), called Og-TENG, which not only possessed high transparence (95%) and stretchability (~387%), but also exhibited excellent electric reliability and mechanical robustness (foldable and twistable) under daily working temperature range (−20°C- 45 °C). The electric performance of Og-TENG is extraordinary, reaching a high instantaneous power density of 4.03 W/m2. The rational design of organogel electrode endowed the Og-TENG with excellent anti-freezing and solvent retention properties. Moreover, the good compatibility between organogel and triboelectric elastomer improved the interface adhesion and further made Og-TENG as a high reliable device under mechanical deformations as compared to high polarity gels based TENGs. The Og-TENG was demonstrated in harvesting bio-mechanical energies and detecting human gestures. This work provides a new strategy to prepare transparent and stretchable TENGs of high power density for reliable and robust energy harvesting in daily working temperature range, exhibiting promising potentials in development of stretchable and multifunctional next-generation electronics.