Self-powered Motion Research Articles

Radio Waveguide-Double Ratchet Rotors Work in Unison on a Surface to Convert Heat into Power.

Synchronizing thousands of 100% efficient rotors in a macrodevice for harvesting noise is unapprehended. Thermodynamically, realizing a thermal gradient at the atomic scale is critical. Harvesting free thermal energy or noise by resonance has a hidden clause; either externally activating a directed self-powered motion or constructing a nanoscale power supply. To accomplish this, we combined two rotor concepts, Brownian rotor, BR, and power stroke, PS, rotors available in living systems in two planes of a single molecule. Quantum tunneling images reveal how a radio-wave guided synchronization of PS-BR combination tweaks rotational dynamics of a rotor to bypass the necessity of temperature gradient (ΔT). Live imaging of thermal noise movement as electron density between a pair of molecular planes helped in optimizing the rotor design. The rotor's monolayer harvests heat from the liquid's Brownian noise and electromagnetic noise, together delivering a finite, usable power. The chip supplies the power if we wet the surface or shine electric noise.

Ultrathin Biocompatible Electrospun Fiber Films for Self-Powered Human Motion Sensor

In recent years, triboelectric nanogenerator (TENG) has been proven to be an effective and simple solution for self-powered wearable sensing, and a wide variety of materials and methods have been applied to TENG based sensors. In this study, an ultrathin fiber film with nanoporous brain-like structure (BUF) was obtained by cold-pressing the electrospun biocompatible fiber mats, and a wearable TENG sensor based on the BUF films that could sensitively detect human motion was demonstrated. This simply designed self-powered sensor was composed of Kapton as the shell and ultrathin, biocompatible poly L-lactic acid and ethyl cellulose (EC) fiber films as the triboelectric layers, prepared by convenient electrospinning method and cold-pressing. Compared to as-spun fiber mats, cold-pressed fiber membranes not only acquire overall compact structure but also remained porous surface morphology, which improved the triboelectric outputs and operational stability of TENG. Three TENGs were fabricated to evaluate the effects of different triboelectric layers on triboelectric outputs, and the BUF-TENG had the maximum triboelectric outputs (19 V, 630 nA at 3.5 Hz) and longer life than as-spun fiber mats based TENG. The BUF-TENG had linear relationship between triboelectric outputs and frequency, and sensitivities of 32.4, 0.94 and 0.22 V Hz−1 in the range of 0.1–0.35, 0.35–2 and 2–3.5 Hz, respectively. Moreover, a self-powered sensor based on the BUF-TENG was proposed to sensitively detect human walking state and limbs motion. With convenient preparation process and biocompatible materials, the BUF-TENG sensor could be a potential self-powered wearable and portable sensor in future health care and monitoring field.

Development of In-Situ Poled Nanofiber Based Flexible Piezoelectric Nanogenerators for Self-Powered Motion Monitoring

Energy harvesting technologies have found significant importance over the past decades due to the increasing demand of energy and self-powered design of electronic and implantable devices. Herein, we demonstrate the design and application of in situ poled highly flexible piezoelectric poly vinylidene fluoride (PVDF) graphene oxide (GO) hybrid nanofibers in aligned mode for multifaceted applications from locomotion sensors to self-powered motion monitoring. Here we exploited the simplest and most versatile method, called electrospinning, to fabricate the in situ poled nanofibers by transforming non-polar α-phase of PVDF to polar β- phase structures for enhanced piezoelectricity under high bias voltage. The flexible piezoelectric device fabricated using the aligned mode generates an improved output voltage of 2.1 V at a uniform force of 12 N. The effective piezoelectric transduction exhibited by the proposed system was tested for its multiple efficacies as a locomotion detector, bio-e-skin, smart chairs and so on.

Ultralow Quiescent Power-Consumption Wake-Up Technology Based on the Bionic Triboelectric Nanogenerator.

Wake‐up circuits in smart microsystems make huge contributions to energy conservation of electronic networks in unmanned areas, which still require higher pressure‐triggering sensitivity and lower power consumption. In this work, a bionic triboelectric nanogenerator (bTENG) is developed to serve as a self‐powered motion sensor in the wake‐up circuit, which captures slight mechanical disturbances and overcomes the drawback of conventional self‐powered motion sensors in the wake‐up circuit that the circuit can only be triggered when a considerable pressure is applied on the sensor. The bTENG mimics the structure of plants and the addition of the leaf‐shaped tentacle structures can increase the electrical outputs by four times, which largely extends the detection range of the wake‐up circuit. The bTENG can detect both noncontact and contact mechanical disturbances; and voltages generated from both situations can trigger the wake‐up system. Moreover, the specially designed circuit that is compatible with the bTENG can help more accurately control the wake‐up system and prolong the battery life of the electronic networks to 12.4 times. An intrusion detection system is established in the wake‐up circuit to distinguish human motion and judge the scene. This work opens new horizons for wake‐up technologies, and provides new routes for persistent sensing.

Multifunctional Water Drop Energy Harvesting and Human Motion Sensor Based on Flexible Dual-Mode Nanogenerator Incorporated with Polymer Nanotubes.

In the world of increasing energy consumption, nanogenerators have shown great potential for energy harvesting and self-powered portable electronics. Herein, a flexible and dual-mode triboelectric nanogenerator (TENG) combining both vertical contact-separation and single electrical modes has been developed to convert environmental mechanical energy into electricity using highly encapsulated and multifunctional strategies. By introducing the polymer melt wetting technique, polymer nanotubes are fabricated on the surface of the TENG, which provides self-cleaning and hydrophobic features beneficial for water drop energy harvesting using the device. In such mechanical energy harvesting, the maximum output power of 0.025 mW and the open-circuit voltage of 41 V can be achieved. By designing the dimensions of the device, the dual-mode TENG is utilized as a self-powered sensor to detect human body motions such as phalanges' movement of fingers. The fabricated dual-mode TENG promotes the development of energy-harvesting and self-powered human motion sensors for artificial intelligent prosthetics, human kinematics, and human body recovery treatment.

Skin-conformal BaTiO3/ecoflex-based piezoelectric nanogenerator for self-powered human motion monitoring

Skin-conformability and lead-free piezo-materials are important for piezoelectric nanogenerator (PENG)-based wearable electronics. Here, a skin-conformal BaTiO3/Ecoflex-based PENG was fabricated by incorporating BaTiO3 particles into an Ecoflex matrix. Due to the inherent elongation of Ecoflex, appropriate thickness of the BTO&Ecoflex film, and optimized polarization, the fabricated device exhibited suitable skin-conformability and high output performance. The output voltage/current reached 8.9 V/49.7 nA with a load resistance of 200 MΩ (effective area: 1.0 cm × 1.0 cm). Due to its suitable skin-conformability and high output performance, the device can be attached to an elbow as an active sensor for the monitoring of joints. In this way, it is promising for medical research and human-machine interaction (HMI) applications. This study is significant for the development of skin-conformal lead-free PENGs.

Self-powered eye motion sensor based on triboelectric interaction and near-field electrostatic induction for wearable assistive technologies

Abstract Triboelectric nanogenerators show great potential as flexible motion transducers for wearable human-machine interfaces (HMI). The present research explores a new configuration named Non-Attached Electrode-Dielectric Triboelectric Sensor (NEDTS) and its application in specialized HMI to support people with disabilities in daily life. In this topology, the conductive electrodes are not bonded to the dielectric materials by any coating or sputtering process. Instead, due to the triboelectric interaction between the two elements in motion, voltage is generated in a separate conductor by non-contact electrostatic induction. This allows a near field remote sensing using triboelectric/electrostatic coupling. By applying the mentioned sensing technique, an Orbicularis Oculi muscle motion sensor has been developed to monitor voluntary and involuntary eye blinks. The new transducer is integrated into a portable HMI for hands-free computer cursor control to assist people with mobility impairment. The conceived device was also tested in other applications as hands-free remote car and drone control, and for monitoring driving behaviour. Additionally, a PDMS-based eyelid motion sensor has been tested to feature other virtues of the NEDTS when sensing unconventional motion dynamics.

Corrosion-resistant and high-performance crumpled-platinum-based triboelectric nanogenerator for self-powered motion sensing

In recent years, triboelectric nanogenerators (TENGs) have drawn great attention as an ideal candidate for the self-powered systems. Methods of enhancing the output performance of the TENG have been extensively studied. However, environmental corrosion of materials still remains an obstacle to its further application. In this work, we proposed the crumpled Pt based TENG with high output performance and corrosion resistance. The device showed maximum voltage of 175.2 V, maximum current of 11.03 μA and maximum output power density of 0.518 mW/cm2. The device also exhibited the excellent reliability under harsh environment and stability in corrosive environment. Furthermore, we demonstrated that the TENG can be easily integrated into gloves to collect human body energy and perform motion detection. This crumpled Pt based TENG can be used as a power supply and sensor device for flexible self-powered systems.

Noncontact triboelectric nanogenerator for human motion monitoring and energy harvesting

Monitoring human motion and harvesting its energy is an interesting and important topic. Triboelectric nanogenerators (TENGs) have shown their potential for signal detecting and energy harvesting. In this paper, a noncontact paper-based TENG is creatively proposed to be used as a self-powered human motion monitoring sensor and also to be used for human motion energy harvesting. The noncontact mode avoids the requirement of direct physical contact between the TENG and the human subject, which fascinates the application of TENG and can increase its service life. It is found that the walking gait cycle (leg raising and falling), moving direction, walking or running speed and moving path can be reflected by the output voltage signals directly and clearly. Noncontact human motion energy harvesting is also achieved by using this TENG with a rectification circuit. It is also surprisingly found that this TENG is able to detect human motion even through a building wall, and the output voltage is strong enough to be captured by a normal multimeter without any additional amplification circuit. This study opens up a new method for self-powered noncontact human movement detecting and monitoring.

A tri-state prismatic modular robotic system

Strut-type modular robots adopt an idealized truss mechanism composed of linear extensible struts (i.e., robotic modules) jointed by connector nodes. Conceptually, each strut is capable of passively rotating around its connected node, and all the struts linked by a same node share and intersect at a common center of rotation. Unfortunately, these two requirements pose difficulties in mechanically implementing such an ideal point-like compliant connector node. Meanwhile, motions of extensible struts composed of off-the-shelf prismatic actuators can be constrained in a parallel or networked robotic structure, leading to the stuck of the robotic structure and the failure of a given task. To tentatively tackle these issues, a tri-state (three-state) modular prismatic robotic system is designed with the ability to be rigid, back-drivable to external forces and to undertake self-powered motion. Two modular robotic concepts of (i) rigid node attachment and (ii) neighbor actuation are introduced and demonstrated. Specifically speaking, modular robotic structures are constituted of prismatic actuators linked by rigid connector nodes. Instead of placing revolute joints on the nodes, a passive revolute joint is in the middle of two prismatic actuators to deliver compliance. This arrangement removes many of the inherent limitations of complex connection joints and avoids the difficulty of designing and implementing point-like complaint connector nodes. In terms of neighbor actuation, modules are demonstrated that they have the ability to be self-powered or passively controlled from external forces applied by their neighboring modules. This allows robotic modules in a parallel or networked structure to change states to release physical constraints and prevent the whole structure from getting stuck. In this paper, the tri-state capability of the prismatic modules and the neighbor actuation of parallel modules are first experimentally demonstrated. Then, two physical modular robots are built and control algorithms are implemented. Experimental results validate the efficacy of the control strategy and substantiate communication and locomotion capabilities of the modular robots. Finally, a more complex robotic structure is established in a robot simulator to demonstrate that the tri-state prismatic actuators can be applied to release physical constraints of the modular robot during a locomotion task.

Facile fabrication of triboelectric nanogenerator based on low-cost thermoplastic polymeric fabrics for large-area energy harvesting and self-powered sensing

Triboelectric nanogenerator (TENG) which can work as novel power provider and self-powered sensor has been in rapid development in recent years. Unfortunately, fabricating large-area TENG through a low-cost, facile, continuous and environmentally friendly method still remains a challenge but highly desired. Herein, via melt blowing technique, a low-cost, durable and large-area fabric-based triboelectric nanogenerator (FB-TENG) was fabricated. Such FB-TENG comprises of polypropylene non-woven fabrics (PP-NWF), commercial polyamide 66 fabrics (PA-66-F) and conductive fabrics (Ni@fabrics). Furthermore, it has remarkable stability even when working for a long time, showing multifunctional applications. For example, on the one hand, as a power provider, FB-TENG can drive miniature electronic products. On the other hand, as a self-powered sensor with extremely short response time, FB-TENG can collect pedestrian volume and monitor pugilism training precisely. This work paves a new way for developing FB-TENG through a low-cost, facile, continuous and environmentally friendly method, showing potential applications including self-powered motion tracking, tactile sensing and remote wireless training monitoring system.

High-performance stretchable PZT particles/Cu@Ag branch nanofibers composite piezoelectric nanogenerator for self-powered body motion monitoring

The development of stretchable nanogenerators has attracted intensive attentions for their promising applications in wearable electronics recently. Here, a newly high-performance stretchable PZT particles/Cu@Ag branch nanofibers (BNFs) nanocomposite piezoelectric generator (NCPG) is reported. The uniform mixture of PZT particles and Cu@Ag BNFs is blended into silicone rubber matrix that exhibits remarkably piezoelectric, mechanical and electrical characteristics. Owing to the similar molding method and the identical elastic matrix, the piezoelectric layer and the electrode layers could be completely integrated into stretchable NCPG based on all-in-one structure, which reveals high output performances (Vpeak–peak ≈ 61 V, Ipeak–peak ≈ 1.1 μA, 22.36 μw cm−3). The generated electricity is utilized to directly light five green emitting diodes (LEDs) and to drive a digital thermometer after stored in capacitor under the mechanical tensile strain stimulation. Moreover, the stretchable NCPG could act as a self-powered body motion sensor for distinguishing the bending angles and frequencies of the knee joint. This work provides a novel design idea for stretchable nanogenerators and shows great potential applications in artificial intelligence, medical diagnosis and movement entertainment.

Seesaw structured triboelectric nanogenerator with enhanced output performance and its applications in self-powered motion sensing

As the world entering the era of internet of things (IoTs), billions of sensor nodes call for the energy for the new era, which is important application of entropy in energy science. Energy harvesting and self-powered technology based on triboelectric nanogenerator (TENG) have been widely recognized as effective solution to providing “random” energy for the “random” units in IoTs. Contact-separation mode, which is one of the most fundamental working mode of TENG, has shown promising potential in mechanical energy harvester and self-powered sensors. In this work, a seesaw structured triboelectric nanogenerator (SS-TENG) is proposed based on contact-separation mode. This structure can largely enhance the relative motion velocity between two tribo-surfaces, and hence improve the output performance of the device. Furthermore, the electric signals of the SS-TENG can be tuned by structure modification to be asymmetric, which can be utilized to monitor the motion direction and velocity of passing objects as well as movement of human foot. After employing C programming, the output signals can be identified and logically analyzed through electric circuits or computers, enabling visual display of sensing results for practical applications. Therefore, this work not only provides a new way of performance enhancement for TENG but also proposes a novel strategy for self-powered motion sensing, showing great potential in the fields of mechanical energy scavenging, traffic monitoring, healthcare sensing, sports rehabilitation, and corrective exercise.

Ionogel-based, highly stretchable, transparent, durable triboelectric nanogenerators for energy harvesting and motion sensing over a wide temperature range

Hydrogel-based triboelectric nanogenerators (H-TENGs) have shown great promise in wearable electronics as soft, stretchable and sustainable power sources. However, H-TENGs can only be used in a narrow temperature range for a short duration due to freezing and evaporation of water. Here, an ionogel-based triboelectric nanogenerator (I-TENG) is designed to significantly broaden the application temperature range and duration while retaining all the superior properties of H-TENGs. The ionogel network constructed by dipole-dipole and ion-dipole interactions exhibits high stretchability (~800%) and ionic conductivity (1.1 mS cm−1). The corresponding I-TENG retains high stretchability (>400%), transparency (>90%), and anti-fatigue resistance (resisting 1000 cycles of 100% stretching) with stable electrical performance for 1 month. The I-TENG shows an instantaneous peak power density of 1.3 W m−2 and efficiently harvests biomechanical energy to drive an electronic watch. Additionally, the I-TENG serves as a self-powered human motion sensor to inspect the bending angle of an elbow. More importantly, the I-TENG retains high stretchability and electrical performance over a wide temperature range from −20 to 100 °C. This work provides a new strategy to design and tailor TENGs that will be very useful for diverse applications, including wearable electronics, electronic skin, and artificial intelligence.

A mathematical model of the locomotion of bacteria near an inclined solid substrate: effects of different waveforms and rheological properties of couple-stress slime

Morphological mutations in bacterial cell make them the most miscellaneous microscopic group. Their non-flagellated species known as gliding bacteria exhibit self-powered motion and leave an adhesive trail of slime. The self-propelled motion in some gliding bacteria is achieved as a result of backward surface wave in the cell envelope. Motivated by this fact, an undulating surface on a layer of couple-stress fluid is used to model the motion of such gliding bacteria. Five different wave profiles, namely, sawtooth, sinusoidal, triangular, trapezoidal, and square profiles are used to model the waveform of the undulating wave in the outer cell surface. The inclination of the surface is also integrated into the model. The flow equations are set up under the lubrication assumption. Stream function is derived as an elementary function of an organism’s speed, undulation amplitude, and couple-stress parameter with its flow rate. Speed of the glider and flow rate (satisfying equilibrium conditions) are computed by employing modified Newton–Raphson method. These refined values are further utilized to compute the power dissipation. Effects of different waveforms, inclination angle, gravitational and couple-stress parameters on the speed of the microorganism and rate of energy expended are also quantified. Slime velocity is also plotted for fixed glider. In addition, making use of the obtained realistic set of values of the organism’s speed, flow rate, occlusion parameter, and couple-stress parameter, streamline patterns of the slime are plotted and discussed in detail.

TriboMotion: A Self-Powered Triboelectric Motion Sensor in Wearable Internet of Things for Human Activity Recognition and Energy Harvesting

Human physical activity recognition is widely used in medical diagnosis, well-being management, and rehabilitation treatment. In spite of various Internet of Things (IoT) designs available in the literature, power resources often limit the lifetime of IoT. Regarding this weakness, this paper develops a new motion sensor system in wearable IoT (WIoT) for human physical activity recognition without any signal conditioning circuits. The triboelectricity-based physical model is explored in designing the motion sensor. It enables to collect motion signals caused by physical activities without any power supply. In addition, the triboelectric structure can be used as an energy harvester for motion harvesting due to its high output voltage in random low-frequency motion and a relatively stable voltage when involving continuous activities. Such a new design lays the foundations for constructing the next generation self-powered WIoT systems. Our new design has been extensively evaluated, where most common activities including sitting and standing, walking, climbing upstairs and downstairs, and running are used. The experimental results demonstrate that our system can achieve similar comparable performance as the state of the art for physical activity recognition at an average successful accuracy of over 80%. At the same time, our system reduces more than 25% energy consumption of the entire sensing hardware system which includes the sensor, microcontroller, and corresponding circuits.

All-in-one filler-elastomer-based high-performance stretchable piezoelectric nanogenerator for kinetic energy harvesting and self-powered motion monitoring

Flexible nanogenerators with advantages of conformal structure and easy assembly have become an appealing research field for wearable electronics recently. Here, an all-in-one filler-elastomer-based high-performance stretchable piezoelectric nanogenerator (SPENG) is reported. By mechanically shearing and uniformly dispersing high weight compositions of PZT particles and Ag-coated glass microspheres fillers into the identical solid state silicone rubber matrixes, the piezoelectric layer and electrode layers are prepared, respectively, and the SPENG can be fabricated in an all-in-one structure with tight adhesion and reliable durability, which is very important to the tension sensing and energy harvesting for the limb motion with large strain and variable degree of freedom. The stretchable energy harvester exhibits excellent output performances (Voc≈20 V, Isc≈0.55μA, 3.93μW/cm3) and can respond to different external stimulations (such as stretched, clustered, folded, twisted, etc.). The SPENG can be not only mounted on a joint to efficiently capture and convert random body kinetic energy into electricity as a power supply for portable electronics, but also used as the self-powered tension and gesture sensors to monitor dynamic motions. This work has demonstrated a great progress in stretchable electronics and energy harvesting technology, which may have important prospects in artificial intelligence and individualized medical care.

Stretchable and Wearable Triboelectric Nanogenerator Based on Kinesio Tape for Self-Powered Human Motion Sensing.

Recently, wearable, self-powered, active human motion sensors have attracted a great deal of attention for biomechanics, physiology, kinesiology, and entertainment. Although some progress has been achieved, new types of stretchable and wearable devices are urgently required to promote the practical application. In this article, targeted at self-powered active human motion sensing, a stretchable, flexible, and wearable triboelectric nanogenerator based on kinesio tapes (KT-TENG) haven been designed and investigated systematically. The device can effectively work during stretching or bending. Both the short-circuit transferred charge and open-circuit voltage exhibit an excellent linear relationship with the stretched displacements and bending angles, enabling its application as a wearable self-powered sensor for real-time human motion monitoring, like knee joint bending and human gestures. Moreover, the KT-TENG shows good stability and durability for long-term operation. Compared with the previous works, the KT-TENG without a macro-scale air gap inside, or stretchable triboelectric layers, possesses various advantages, such as simple fabrication, compact structure, superior flexibility and stability, excellent conformable contact with skin, and wide-range selection of triboelectric materials. This work provides a new prospect for a wearable, self-powered, active human motion sensor and has numerous potential applications in the fields of healthcare monitoring, human-machine interfacing, and prosthesis developing.

Uniformly assembled vanadium doped ZnO microflowers/ bacterial cellulose hybrid paper for flexible piezoelectric nanogenerators and self-powered sensors

As good alternatives for conventional rigid piezoelectric materials, piezoelectric nanocomposites combining piezoelectric materials and flexible polymer matrix demonstrate great potential for flexible nanogenerators. Rational design of the hybrid structure is important for performance optimization of piezoelectric nanocomposite. Here, we designed a hybrid piezoelectric paper through uniform assembly of vanadium doped ZnO (V-ZnO) mircoflowers in bacterial cellulose (BC) matrix by a in situ synthesis method. Different from pure ZnO where the c-axis of crystalline need to be oriented in order to get improved piezoelectric output, V-ZnO demonstrate ferroelectric property, which is prerequisite for poling with external high voltage in enhancing the output performance. The resultant hybrid paper demonstrated excellent flexibility and was used to fabricate flexible piezoelectric nanogenerators (PENGs). With excellent mechanical strength and durability, the V-ZnO/BC hybrid paper-based PENGs can work as self-powered motion sensors, which are capable of monitoring page-turning motions when integrated with pages of books. The V-ZnO/BC hybrid paper based PENGs are lightweight and inexpensive, which demonstrate promising applications for self-powered sensor networks and wearable electronics.

Self-Powered Multifunctional Motion Sensor Enabled by Magnetic-Regulated Triboelectric Nanogenerator.

With the fast development of the Internet of Things, the requirements of system miniaturization and integration have accelerated research on multifunctional sensors. Based on the triboelectric nanogenerator, a self-powered multifunctional motion sensor (MFMS) is proposed in this work, which is capable of detecting the motion parameters, including direction, speed, and acceleration of linear and rotary motions, simultaneously. The MFMS consists of a triboelectric nanogenerator (TENG) module, a magnetic regulation module, and an acrylic shell. The TENG module is formed by placing a free-standing magnetic disk (MD) on a polytetrafluorethylene (PTFE) plate with six copper electrodes. The movement of the MFMS causes the MD to slide on the PTFE plate and hence excites the electrodes to produce a voltage output. The carefully designed six copper electrodes (an inner circle electrode, an outer circle electrode, and four arc electrodes between them) can distinguish eight directions of movement with the acceleration and determine the rotational speed and direction as well. Besides, the magnetic regulation module is applied here by fixing a magnetic cylinder (MC) in the shell, right under the center of the PTFE plate. Due to the magnetic attraction applied by the MC, the MD will automatically return to the center to prepare for the next round of detection, which makes the proposed sensor much more applicable in practice.