Biomechanical Energy Harvesting Research Articles

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

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

Implanted Carbon Nanotubes Harvest Electrical Energy from Heartbeat for Medical Implants.

Reliability of power supply for current implantable electronic devices is a critical issue for longevity and for reducing the risk of device failure. Energy harvesting is an emerging technology, representing a strategy for establishing autonomous power supply by utilizing biomechanical movements in human body. Here, a novel "Twistron energy cell harvester" (TECH), consisting of coiled carbon nanotube yarn that converts mechanical energy of the beating heart into electrical energy, is presented. The performance of TECH is evaluated in an in vitro artificial heartbeat system which simulates the deformation pattern of the cardiac surface, reaching a maximum peak power of 1.42W kg-1 and average power of 0.39W kg-1 at 60 beats per minute. In vivo implantation of TECH onto the left ventricular surface in a porcine model continuously generates electrical energy from cardiac contraction. The generated electrical energy is used for direct pacing of the heart as documented by extensive electrophysiology mapping. Implanted modified carbon nanotubes are applicable as a source for harvesting biomechanical energy from cardiac motion for power supply or cardiac pacing.

Incorporating MIL‐125 Metal‐Organic Framework for Flexible Triboelectric Nanogenerators and Self‐Powered Sensors for Robotic Grippers

AbstractTriboelectric nanogenerators (TENGs) are getting popular as biomechanical energy harvesters to power small electronic devices and as self‐powered sensors for pressure, motion, vibration, wind, waves, biomedical information, and chemical substance detections. In this study, the TENG is designed with biocompatible materials, and concentrations of its components have been optimized to generate higher power for application as an energy source and tactile sensor. The process involves using metal‐organic frameworks (MOFs), namely MIL‐125, with high charge‐inducing and charge‐trapping capabilities incorporated into the commercial Ecoflex matrix. Electrical characterization demonstrated that the sample with 0.25 wt% MIL‐125 (0.25%MOF/Ecoflex) is the optimal concentration in the matrix with an output of up to 305 V and 13 µA, respectively. Moreover, the proposed flexible TENG converts mechanical energy to electrical, with a maximum power density of 150 µW cm−2 (1.5 W m−2), which is more than twice superior to the pristine Ecoflex‐based counterparts. The TENG shows robust and stable performance without noticeable degradation during continuous 200,000 cyclic testing. Furthermore, 0.25%MOF/Ecoflex TENG can power small electronic devices such as calculators, humidity sensors, and cardiac pacemakers. A robotic gripper trained via machine learning to identify various objects is also successfully developed with a self‐powered 0.25%MOF/Ecoflex TENG sensor.

Biomechanical energy harvesting technologies for wearable electronics: Theories and devices

AbstractWearable biomechanical energy harvesting devices have received a lot of attention recently, benefiting from the rapid advancement of theories and devices in the field of the micro electromechanical system (MEMS). They not only fulfil the requirements for powering wearable electronic devices but also provide an attractive prospect for powering self-powered flexible electronic devices when wearing. In this article, we provide a review of the theories and devices of biomechanical energy harvesting technology for wearable applications. Three different forms of biomechanical energy harvesting mechanisms, including the piezoelectric effect, electromagnetic effect, and electrostatic effect, are investigated in detail. The fundamental principle of converting other types of energy from the biomechanical environment into electrical energy, as well as the most commonly-used analytical theoretical models, are outlined for each process. Therefore, the features, properties, and applications of energy harvesting devices are summarized. In addition, the coupled multi-effect hybrid energy harvesting devices are listed, showing the various possibilities of biomechanical energy harvesting devices for serving as sources, sensors, and actuators. Finally, we present perspectives on the future trends of biomechanical energy harvesting devices for wearable electronics applications.

Using multi-criteria decision-making approach for material alternatives in TiO2/P(VDF-TrFE)/PDMS based hybrid nanogenerator as a wearable device

P(VDF-TrFE)/TiO2/PDMS-based hybrid nanogenerators with excellent piezoelectric performance are of particular interest for the development of sensors, wearable devices, and low-cost biomechanical energy harvesters. In this work, hybrid nanogenerator (HNG) is designed to enhance the energy output by integrating piezoelectric and triboelectric effects. P(VDF-TrFE)/TiO2 nanocomposites are synthesized using electrospinning to design hybrid nanogenerator for energy harvesting from a manual activity. The hybrid nanogenerator device generated 5.36µA current across 10 MΩ resistor and 52V electric voltage. An analysis of the effect of varying TiO2 on hybrid nanogenerators is reported here for the first time. The best material for biomechanical energy harvesting applications is selected using a multi-criteria decision-making (MCDM) based material selection and optimization technique TODIM, along with a sensitivity study. SA-4 type nanocomposite is the most suitable material as per the TODIM approach. This nanogenerator shows better performance than most nanogenerators designed with complex and sophisticated approaches.

Color-tunable, multifunctional photochromic composites for wearable UV monitoring and biomechanical energy harvesting

Color-tunable, multifunctional photochromic composites for wearable UV monitoring and biomechanical energy harvesting

Biomechanical MEMS Electrostatic Energy Harvester for Pacemaker Application: A Study of Optimal Interface Circuit.

The leadless pacemaker is the most recent pacemaker concept, developed to overcome conventional pacemakers' limitations. This technology offers better comfort to the patients, lower risk from implantation, and higher reliability. However, these devices suffer from limited battery lifetime due to the extreme miniaturization required for implantation inside the heart cavities. This work proposes extending the battery lifetime by converting biomechanical heartbeat energy into electricity using an innovative electrostatic MEMS energy harvesting device. Based on theoretical models and experiments, we propose a general approach to choosing the optimal interface circuit which considers the parasitic capacitance of the circuit, as it is an imperfection that significantly affects the power performance. According to the energy consumed by the last generation commercial leadless pacemakers, the proposed MEMS solution with optimal interface circuit experimentally showed the possibility of extending the pacemaker battery lifetime by up to 44%.

Perovskite Nanocrystals Induced Core-Shell Inorganic-Organic Nanofibers for Efficient Energy Harvesting and Self-Powered Monitoring.

The emerging field of wearable electronics requires power sources that are flexible, lightweight, high-capacity, durable, and comfortable for daily use, which enables extensive use in electronic skins, self-powered sensing, and physiological health monitoring. In this work, we developed the core-shell and biocompatible Cs2InCl5(H2O)@PVDF-HFP nanofibers (CIC@HFP NFs) by one-step electrospinning assisted self-assembly method for triboelectric nanogenerators (TENGs). By adopting lead-free Cs2InCl5(H2O) as an inducer, CIC@HFP NFs exhibited β-phase-enhanced and self-aligned nanocrystals within the uniaxial direction. The interface interaction was further investigated by experimental measurements and molecular dynamics, which revealed that the hydrogen bonds between Cs2InCl5(H2O) and PVDF-HFP induced automatically well-aligned dipoles and stabilized the β-phase in the CIC@HFP NFs. The TENG fabricated using CIC@HFP NFs and nylon-6,6 NFs exhibited significant improvement in output voltage (681 V), output current (53.1 μA) and peak power density (6.94 W m-2), with the highest reported output performance among TENGs based on halide-perovskites. The energy harvesting and self-powered monitoring performance were further substantiated by human motions, showcasing its ability to charge capacitors and effectively operate electronics such as commercial LEDs, stopwatches, and calculators, demonstrating its promising application in biomechanical energy harvesting and self-powered sensing.

Porous, Self-Polarized Ferroelectric Polymer Films Exhibiting Behavior Reminiscent of Morphotropic Phase Boundary Induced by Size-Dependent Interface Effect for Self-Powered Sensing.

Piezoelectric poly(vinylidene fluoride) (PVDF) and its copolymer, poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)), have attracted considerable attention due to their potential in flexible, biocompatible energy harvesting and sensing devices. However, their limited piezoelectric performance hinders their widespread application. Inspired by the concept of morphotropic phase boundary (MPB) prevalent in high-performance piezoelectric ceramics, we successfully constructed MPB in the piezoelectric polymer P(VDF-TrFE) through size-dependent interface effects. We provided direct structural evidence using atomic force microscopy-infrared spectroscopy (AFM-IR) and significantly improved the piezoelectric performance of P(VDF-TrFE). The emergence of MPB is attributed to the interface effect induced by electrostatic interactions between ZnO fillers and the -CH2, -CF2, and -CHF groups in P(VDF-TrFE). This interaction drives a concomitant competition between the all-trans β phase (normal ferroelectric) and the 3/1 helical phase (relaxor), resulting in enhanced piezoelectric responses in the transition region. By coupling the MPB effect with a porous structure, we developed a piezoelectric nanogenerator (PENG) that surpasses the electrical output limitation of current P(VDF-TrFE)-based PENGs. The fabricated PENG exhibits superior piezoelectric outputs (6.9 μW/cm2), impressive pressure sensitivity (2.3038 V/kPa), ultrafast response time (4.3 ms), and recovery time (46.4 ms)─notably, without the need for additional poling treatment. In practical applications, the constructed PENG can efficiently generate characteristic signals in response to various human movements and harvest biomechanical energy. This work offers insight into utilizing interface-induced MPB and proposes a simple, scalable approach for developing high-performance self-polarized piezoelectric polymer films for self-powered sensing systems toward human-machine interaction.

Low-dimensional halide perovskite/PVDF nanocomposite with enhanced piezoelectricity as flexible biomechanical energy harvester

Sustainable energy harvesting is the need of the hour, and piezoelectric nanogenerators (PENG) offer tremendous opportunities in this field. We have investigated the mechanical energy harvesting applications of a nanocomposite comprising a low-dimensional halide perovskite (HP) and polyvinylidene fluoride (PVDF). Cs4PbBr6 HP was prepared using mechanochemical synthesis, and a composite film of PVDF with Cs4PbBr6 was utilized as the PENG to scavenge energy from day-to-day human biomechanical activities. The properties and output results of the fabricated devices with changing weight percentages (wt.%) of HP used as nanofillers in the PVDF matrix are compared to those of a pure PVDF. A 6 wt.% concentration of Cs4PbBr6 induces the composite's electroactive β-phase to around 87%. The polarization hysteresis (P-E) loop measurement reveals a remanent polarization of 0.31 µC/cm2. The measured piezoelectric coefficient (d33) is about ⁓12 pm/V, and the piezoelectric amplitude is ∼500 pm for the optimized PENG at the maximum applied bias of ±30 V. The device shows an instantaneous output voltage of ⁓90 V, a current of ⁓3.8 μA, and power of ⁓80 µW across a 5 MΩ resistor. Simple daily human activities like finger tapping, leg-toe pressing, finger bending, heel pressing, and walking are used to generate output voltages using PENG with prospective usage in powering portable electronic devices. The output AC voltage of the device is employed to charge a 10 µF capacitor up to ∼3.5 V and shows exceptional stability over long cycles. The output power generated is adequate for lighting commercial LEDs without any external input. The Cs4PbBr6/PVDF composite films thus demonstrate significant potential to be deployed as high-performance, portable, and wearable mechanical energy harvesting devices.

Flexible Triboelectric Nanogenerators based on Hydrogel/g-C3N4 Composites for Biomechanical Energy Harvesting and Self-Powered Sensing.

Flexible and stretchable triboelectric nanogenerators (TENGs) have been rapidly advanced owing to the demand for portable and wearable electronic devices that can work under universal or motional circumstances. While versatile materials can be applied in a TENG as dielectric materials, flexible and cost-effective electrodes are crucially important for the output performance of TENGs. Herein, we developed a poly(vinyl alcohol) (PVA) hydrogel TENG doped with a novel two-dimensional material, graphitic carbon nitride (g-C3N4), which could act as both a cost-effective flexible electrode and a positive dielectric for TENG with different morphologies. The measured peak-to-peak open-circuit voltage of the TENG reached 80 V at a dopant concentration of 2.7 wt % in single-electrode mode, which is far higher than that of the pristine PVA hydrogel TENG. As a demonstration of the application, the g-C3N4/PVA hydrogel TENG can be adopted as electronic skin to monitor the movement of the human body. Low-frequency mechanical energy-harvesting devices in different morphologies including discoid flake shape, tube shape, and spiral shape in the single-electrode mode or contact-separation mode have been designed, fabricated, and evaluated. All of these merits of the proposed hydrogel TENG after doping two-dimensional (2D) material g-C3N4 have demonstrated their promising potential for versatile applications in biomechanical energy harvesting and self-powered sensing.

Enhancing electrical output and thermal adaptivity in an interlocked core-sheath triboelectric yarn/fabric for intelligent fire-rescue systems

Self-powered flexible electronic textiles designed for fire-rescue functions, especially in high-temperature environments, have attracted considerable attention. However, their practical applications are hindered by limited electrical output and poor thermal adaptability. In this study, we develop an interlocked core-sheath triboelectric yarn (ICSTY) employing a well-established braiding process, which comprises an inner layer of braided conductive yarn and an outer layer of loop-piled polyimide yarn. This unique structural design resulted in the ICSTY exhibiting an enhanced electrical output performance of 16.3 V per length of 15 cm and excellent thermal adaptability across a wide temperature range of 25–250 °C. The woven ICSTY fabric demonstrates outstanding thermal insulation and biomechanical energy harvesting compared with existing firefighting uniforms. Furthermore, it can be seamlessly integrated into a self-powered fire-rescue system for motion monitoring, location acquisition, and escape warnings for trapped firefighters. This exceptional ICSTY holds the potential to significantly impact the future development of intelligent firefighting uniforms.

A Triboelectric Nanogenerator Based on Bamboo Leaf for Biomechanical Energy Harvesting and Self-Powered Touch Sensing

Recently, natural material-based triboelectric nanogenerators (TENGs) have increasingly attracted attention in academic circles. In this work, we have developed an innovative triboelectric nanogenerator (BL-TENG) utilizing bamboo leaves to capture biomechanical energy. Bamboo leaf, as a natural plant material, possesses a diverse array of applications due to its remarkable durability, which surpasses that of many other types of trees. Furthermore, bamboo leaf has the advantages of low cost, widely distributed, non-toxic and environmentally protected. The output power of the BL-TENG (size: 5 cm × 5 cm) is able to generate approximately 409.6 µW and the internal resistance of the BL-TENG is 40 MΩ. Furthermore, the BL-TENG can realize an open-circuit voltage (Voc) of 191 V and a short-circuit current (Isc) of 5 µA, respectively. The biomechanical energy harvesting effect of the BL-TENG device means that it can drive 18 commercial light-emitting diodes (LEDs) through the full-wave bridge rectifier. Furthermore, the BL-TENG can also serve as a self-powered touch sensor to reflect hand touch states. This study proposed a novel plant-based TENG device that can enhance the development of green TENG devices and self-powered sensing systems.

High-Performance All-Textile Triboelectric Nanogenerator toward Intelligent Sports Sensing and Biomechanical Energy Harvesting.

Merging textiles with advanced energy harvesting technology via triboelectric effects brings novel insights into self-powered wearable textile electronics. However, fabrication of a comfortable textile-based triboelectric nanogenerator (TENG) with high outputs remains challenging. Herein, we propose a highly flexible, tailorable, single-electrode all-textile TENG (t-TENG) with both wear comfort and high outputs. A dielectric modulated porous composite coating containing poly(vinylidene fluoride)-hexafluoropropylene copolymer and barium titanate nanoparticles is constructed on conductive fabric to counterpart with highly positive glass fiber fabric through knotted yarn bonding, maintaining the superiority of textiles and strong triboelectricity. Through the synergistic optimization of charge storage via dielectric modulation and charge dissipation offset by electrical poling, remarkable outputs (261 V, 1.5 μA, and 12.7 nC) are obtained from a miniaturized, lightweight t-TENG (2 × 2 cm2, 130 mg) with an instantaneous power density of 654.48 mW·m-2, as well as excellent electrical robustness and device durability over 20,000 cycles. The t-TENG also exhibits a high sensitivity of 3.438 V·kPa-1 in the force region (1-10 N), demonstrating great potential in TENG-based intelligent sports sensing applications for monitoring and correcting the basketball shooting hand and foot arch posture. Furthermore, over 110 light-emitting diode arrays can be lightened up by gently tapping this miniaturized t-TENG. It also offers a wearable power source scheme through integrating the single-electrode device into clothing and utilizing the skin as the grounded electrode, revealing its ease of integration and biomechanical energy harvesting capability. This work provides an attractive paradigm for next-generation textile electronics with well-balanced device performance and wear comfort.

Electricity out of electronic trash: Triboelectric nanogenerators from discarded smartphone displays for biomechanical energy harvesting

In the context of escalating electronic waste (e-waste) generated by the rapid evolution of electronic devices, particularly smartphones/mobiles, the imperative for effective e-waste management to mitigate adverse environmental and health consequences has become increasingly apparent. Herein, novel mobile phone-based triboelectric nanogenerators (M-TENGs) are fabricated from discarded smartphone displays of eight different brands (B1-B8) for harvesting electrical energy. Analytical characterization techniques such as SEM and EDS are employed for morphological investigation. The tribopositivity and tribonegativity of the smartphone display layers are confirmed using the FTIR technique and test materials. The percentage tensile strength of the selected triboactive layers is measured to assess the mechanical durability. The electrical measurements are performed for all eight M-TENG devices, notably the device constructed from B8 smartphone display layers outperforms other brands by generating about three and five times higher voltage and current than the M-TENG device composed of B1 layers. Further, the optimized device is subjected to frequency, force, and stability tests, and also the impact of fluctuating humidity on the device performance is analyzed. Moreover, the M-TENG demonstrates its versatility by efficiently charging commercial electrolytic capacitors, powering LEDs, and effectively harvesting biomechanical energy. Thus, the present study represents a significant step towards mitigating the challenges posed by electronic smartphone waste disposal while simultaneously offering a viable pathway to harvest electricity and power a variety of applications.

Textured nanofibers inspired by nature for harvesting biomechanical energy and sensing biophysiological signals

Flexible electronics are emerging as a promising new platform for wearables; however, their practical utility is hindered by the limited battery life of electronic devices and the need for frequent battery replacements. Here, we report self-powered, flexible, permeable, tough, and lightweight biomechanical energy harvesting and biophysiological sensing devices using textured nanofibers for wearable electronics applications. The textured structure draws inspiration from two major sources of nature: the interior porous structure of jute fibers and the rough bark texture of trees. Interior pores are introduced to the nanofibers to increase compressibility and breathability like jute fibers. The inspiration from the rough bark texture also leads to a wrinkled surface morphology of the nanofibers to expand the surface area and consequently enhance toughness. To design and fabricate such a textured structure, the vapor-induced phase separation mechanism and electrospinning technique are employed within a controllable high humidity environment. Consequently, the textured nanofiber-based devices exhibit a well-rounded performance in electrical, mechanical, and physical properties, specifically demonstrating a significantly enhanced piezoelectric performance with more than two-fold electrical generation. These textured devices not only effectively harvest biomechanical energy from human movement but also demonstrate sensing capability for self-powered multifunctional biophysiological monitoring applications by leveraging the same piezoelectric mechanism. The novel design strategy for the textured nanofibers and their resultant balanced performance promotes the versatility and practical applicability of piezoelectric fibrous energy harvesting and sensing devices, contributing to the development of next-generation flexible and wearable electronics.

A self-powered intracardiac pacemaker in swine model

Harvesting biomechanical energy from cardiac motion is an attractive power source for implantable bioelectronic devices. Here, we report a battery-free, transcatheter, self-powered intracardiac pacemaker based on the coupled effect of triboelectrification and electrostatic induction for the treatment of arrhythmia in large animal models. We show that the capsule-shaped device (1.75 g, 1.52 cc) can be integrated with a delivery catheter for implanting in the right ventricle of a swine through the intravenous route, which effectively converts cardiac motion energy to electricity and maintains endocardial pacing function during the three-week follow-up period. We measure in vivo open circuit voltage and short circuit current of the self-powered intracardiac pacemaker of about 6.0 V and 0.2 μA, respectively. This approach exhibits up-to-date progress in self-powered medical devices and it may overcome the inherent energy shortcomings of implantable pacemakers and other bioelectronic devices for therapy and sensing.

Snake-scale stimulated robust biomimetic composite triboelectric layer for energy harvesting and smart health monitoring

Extreme frictional wear of triboelectric layers severely hinders long-term sustainability of triboelectric nanogenerators (TENGs) for efficient ambient energy harvesting. The state-of-the-art solutions necessitate sophisticated structural designs and complex packaging constraints, impeding the feasibility of TENGs for practical applications. Herein, inspired by the structures and compositions of snake scales, a biomimetic composite (BC) film is fabricated as a wear-resistant triboelectric contact layer. The successful formation of disulfide bond-facilitated cross-linkage of cysteine proteins in the keratin-based BC film promotes excellent mechanical resilience and durability, thereby solving the material abrasion challenges associated with solid-solid triboelectric layers. The BC film, with toothed microstructure, exhibits improved charge transfer, low friction, and consistent long-term stable outputs compared to commercial films. Furthermore, a self-powered BC film-based TENG is integrated into a bicycle for biomechanical energy harvesting, lightening warning signals for safer night ride with stable 300 V electrical output for at least 6 h. Moreover, a smart health monitoring system is further proposed by embedding TENG-based sensors into the bicycle saddle, accurately capturing the rider’s pelvic-saddle interactions on varying terrain slopes. By leveraging the unique biomechanical information, machine learning-assisted user identification and terrain slope data classifications are achieved with high accuracies, laying a foundation for futuristic smart healthcare applications. This work provides a strategy to reduce material abrasion by exploiting the unique characteristics of a biomimetic material, facilitating a basis for efficient environmental energy harvesting and smart sensing.

Multimodal Energy Generation and Intruder Sensing Platform via Aluminum Titanate/Poly‐Glucosamine Composite Film‐Based Hybrid Nanogenerators

AbstractRecently, a new class of portable self‐powered electronic systems is developed that utilizes highly efficient hybrid nanogenerators that convert mechanical energy into electricity to power various sensors/small‐scale electronics. This article proposes aluminum titanate (Al2TiO5) microparticles (AlT MPs) loaded poly‐glucosamine (PGA) composite film‐based high‐performance hybrid nanogenerators (HNG) employed as a self‐powered sensor for signal indication and as an intruder sensing platform. Initially, AlT MPs are synthesized and various concentrations are loaded into PGA. HNGs are fabricated using composite films/ polydimethylsiloxane, and Al as the positive/negative triboelectric layers and electrode film, respectively. The fabricated HNGs operate in the contact‐separation mode and their produced electrical outputs are comparatively studied to determine the most suitable AlT concentration. The optimized HNG produces the highest electrical output of ≈211 V, ≈5.5 µA, and 79.5 µC/m2. The optimized HNG is employed as a biomechanical energy harvester to scavenge energy from various biomechanical movements and power portable electronics utilizing the developed highly efficient power management circuit. Thereafter, multiple HNGs are utilized to fabricate a self‐powered wireless sensing system and real‐time intruder sensing platform. The proposed highly efficient HNG‐based self‐powered wireless sensing platform is a promising technology that can be used on a large scale in various applications.

Graphene Nanoplatelet Integrated Thermally Drawn PVDF Triboelectric Nanocomposite Fibers for Extreme Environmental Conditions

AbstractTriboelectric nanogenerators (TENGs) utilize the synergetic effect of triboelectrification and electrostatic induction to guide electrons through an external circuit, enabling low‐frequency mechanical and biomechanical energy harvesting and self‐powered sensing. Integrating 2D material with a high specific surface area into flexible ferroelectric polymers such as polyvinylidene difluoride (PVDF) has proven to be an efficient strategy to improve the performance of TENG devices. Scalable fabrication of graphene‐integrated PVDF nanocomposite fiber using thermal drawing process is demonstrated for the first time in this study. The open‐circuit voltage and short‐circuit current show 1.41 times and 1.48 times improvement with the integration of 5% graphene in the PVDF fibers, respectively. The TENG fabric shows a maximum power output of 32.14 µW at a matching load of 7 MΩ and a power density of 53.57 mW m−2. The fibers exhibit excellent stability in harsh environmental conditions such as alkaline medium, high/low temperature, multi‐washing cycle, and long‐time usage.