Self-powered wireless environmental monitoring system for in-service bridges by galloping piezoelectric-triboelectric hybridized energy harvester

The energy harvesting technology for the ubiquitous natural wind enables a desirable solution to the issue of distributed sensors in the bridge environmental sensing Internet of Things(Io T)system being restricted to conventional energy supply.In this work,a self-powered system based on a compact galloping piezoelectric-triboelectric energy harvester(GPTEH)is developed to achieve efficient wind energy harvesting.The GPTEH is constructed on the prototype of a cantilever structure with piezoelectric macro-fiber composite(MFC)sheets and a rectangular bluff body with triboelectric nanogenerators(TENGs).Through a special swing-type structural design with iron blocks inside the bluff body,the GPTEH exhibits preferable aerodynamic behavior and excellent energy conversion efficiency,compared to conventional cantilever kind of piezoelectric wind energy harvester(PWEH).The GPTEH also demonstrates the capability of high output power density(PEH of 23.65 W m^(-2)and TENG of 1.59 W m^(-2)),superior response wind speed(about 0.5 m s^(-1)),and excellent long-term stability(over 14000 cyclic tests).Furthermore,a power management system is developed to efficiently utilize the output energy from GPTEH to power the sensors and wirelessly transmit environmental data to the terminals.The proposed GPTEH-powered system exhibits a great potential for the bridge environmental monitoring and Io T technologies.

A soft-contact hybrid electromagnetic–triboelectric nanogenerator for self-powered water splitting towards hydrogen production

The effective acquisition of hydrogen energy from the ocean offers a promising sustainable solution for increasing global energy shortage.Herein,a self-powered high-efficient hydrogen generation system is proposed by integrating a triboelectric–electromagnetic hybrid nanogenerator(TEHG),power management circuit(PMC),and an electrolytic cell.Under the wind triggering,as-fabricated TEHG can effectively convert breeze energy into electric energy,which demonstrates a high output current of 20.3 mA at a speed rotation of 700 rpm and the maximal output power of 13.8 mW at a load of 10 MΩ.Remarkably,asdesigned self-powered system can perform a steady and continuous water splitting to produce hydrogen(1.5μL·min^(−1))by adding a matching capacitor between the PMC and electrolytic cell.In the circuit,the capacitor can not only function as a charge compensation source for water splitting,but also stabilize the working voltage.Unlike other self-powered water splitting systems,the proposed system does not need catalysts or the complex electrical energy storage/release process,thus improving the hydrogen production efficiency and reducing the cost.This work provides an effective strategy for clean hydrogen energy production and demonstrates the huge potential of the constructed self-powered system toward carbon neutralization.

Linear-grating hybridized electromagnetic-triboelectric nanogenerator for sustainably powering portable electronics

Utilizing a nanogenerator to scavenge mechanical energy from our living environment is an effective method to solve the power source issue of portable electronics. We report a linear-grating hybridized electromagnetic-triboelectric nanogenerator for scavenging the mechanical energy generated from sliding motions to sustainably power certain portable electronics. The hybridized nano- generator consists of a slider and a stator in the structural design, and possesses a 66-segment triboelectric nanogenerator （TENG） and a 9-segment electromagnetic generator （EMG） in the functional design. At a sliding acceleration of 20 m/s2 the hybridized nanogenerator can deliver maximum powers of 102.8 mW for the TENG at a loading resistance of 0.4 Mr2 and 103.3 mW for the EMG at a loading resistance of 6 kf2. With an optimal hybridized combination of the TENG with a transformer and the EMG with a power management circuit, a 10 mF capacitor can be easily charged to 2.8 V in 20 s. A packaged hybridized nanogenerator with a light weight of 140 g and small dimensions of 12 cm× 4 cm× 1.6 cm excels in scavenging low-frequency sliding energy to sustainably power portable electronics.

A hybridized electromagnetic-triboelectric nanogenerator designed for scavenging biomechanical energy in human balance control

For human beings of different ages and physical abilities, the inherent balance control system is ubiquitous and active to prevent falling, especially in motion states. A hybridized electromagnetic-triboelectric nanogenerator (HETNG) is prepared to harvest biomechanical energy during human balance control processes and achieve significant monitoring functions. The HETNG is composed of a symmetrical pendulum structure and a cylinder magnet rolling inside. Four coils are divided into two groups which form into two electromagnetic generators (EMGs). Besides, two spatial electrodes attached to the inner wall constitute a freestanding mode triboelectric nanogenerator (TENG). With a rectification circuit, the HETNG presents a high output power with a peak value of 0.55 W at a load of 160 Ω. Along with human balance control processes during walking, the HETNG can harvest biomechanical energy at different positions on the trunk. Moreover, the HETNG applied in artificial limb has been preliminarily simulated with the positions on thigh and foot, for monitoring the actions of squat and stand up, and lifting the leg up and down. For the elder that walks slowly with a walking aid, the HETNG equipped on the walking aid can help to record the motions of forwarding and unexpected falling, which is useful for calling for help. This work shows the potential of biomechanical energy-driven HETNG for powering portable electronics and monitoring human motions, also shows significant concerns to people lacked action capability or disabled.

Whirligig‑Inspired Hybrid Nanogenerator for Multi‑strategy Energy Harvesting

Portable energy solutions are highly desired in the era of the Internet of Things for powering various distributed micro-electronic devices.At the same time,the energy crisis and catastrophic global warming are becoming serious problems in the world,emphasizing the urgent need for clean and renewable energy.Here,we report a low-cost,high-performance,and portable hand-driven whirligig structured triboelectric–electromagnetic hybrid nanogenerator(whirligig-HNG)for multi-strategy energy harvesting.The whirligig-HNG comprises a dynamic supercoiling TENG via the pulling-strings and inner-distributed EMGs(variable number)in the rotator.The whirligig structure can readily convert linear displacement in low frequency into rotary motion in extremely high frequency.Based on this ingenious design,the whirligig-HNG is capable to harvest the triboelectric energy from the supercoiling/uncoiling process from the pulling strings and simultaneously utilize the high-frequency rotation energy via electromagnetic induction.We have systematically investigated the working mecha-nism of the whirligig-HNG for coupled energy harvesting and compared the individual characteristics of TENG and EMG.The whirligig-HNG is successfully demonstrated to light up more than 100 commercial light-emitting diodes(LEDs)and drive portable electronics.This research presents the enormous potential of whirligig-HNG as a manual and portable power supply for powering various portable electronics.

Stretchable nanogenerators for scavenging mechanical energy

Using stretchable nanogenerators to obtain disordered mechanical energy from the environment is an ideal way to realize wearable power supply equipment and self-power electronic devices,and alleviate the energy crisis.It is of great significance to integrate the stretchability into the nanogenerator,which can fit the complex shape of the target object better and is well suitable for wearable electronics.When applied to the human body,it can directly harvest human body mechanical energy to power wearable electronic devices and get rid of the trouble of charging.This paper systematically reviewed nanogenerators in stretchability,focusing on stretchable triboelectric nanogenerators,stretchable piezoelectric nanogenerators,and stretchable hybrid nanogenerators.Their physical mechanism,material selection,structure design,and output performance are discussed in detail.It is concluded that the fabrication methods of various devices can be broadly categorized into the two most important device types,namely fiber-like and planar.A detailed analysis of representative work and the latest progress in the past decade is performed.It is most important that excellent stretchability and high-power output are the key point to realize application value of stretchable nanogenerators.In addition,we discuss opportunities and challenges,as well as future development direction of stretchable nanogenerators.

Hybrid electromagnetic-triboelectric nanogenerator for harvesting vibration energy

We report a hybrid nanogenerator that includes a triboelectric nanogenerator （TENG） and an electromagnetic generator （EMG） for scavenging mechanical energy. This nanogenerator operates in a hybrid mode using both the triboelectric and electromagnetic induction effects. Under a vibration frequency of 14 Hz, the fabricated TENG can deliver an open-circuit voltage of about 84 V, a short-circuit current of 43 μA, and a maximum power of 1.2 mW （the corresponding power per unit mass and volume are 1.82 mW/g and 3.4 W/m^3, respectively） under a loading resistance of 2 MΩ, whereas the fabricated EMG can produce an opencircuit voltage of about 9.9 V, a short-circuit current of 7 mA, and a maximum power of 17.4 mW （the corresponding power per unit mass and volume are 0.53 mW/g and 3.7 W/m^3, respectively） under a loading resistance of 2 kΩ. Impedance matching between the TENG and EMG can be achieved using a transformer to decrease the impedance of the TENG. Moreover, the energy produced by the hybrid nanogenerator can be stored in a home-made Li-ion battery. This research represents important progress toward practical applications of vibration energy generation for realizing self-charging power cells.

Fully enclosed hybrid electromagnetic-triboelectric nanogenerator to scavenge vibrational energy

We propose a fully enclosed hybrid nanogenerator consisting of five elec- tromagnetic generators （EMGs） and four triboelectric nanogenerators （TENGs）. Under a vibration frequency of 15.5 Hz, one TENG can deliver a high output voltage of approximately 24 V and a low output current of approximately 24 μA, whereas one EMG can deliver a low output voltage of approximately 0.8 V and a high output current of approximately 0.5 mA. By integrating five rectified EMGs in series and four rectified TENGs in parallel, the hybrid nanogenerator can be used to charge a home-made Li-ion battery from 1 to 1.9 V in 6.3 h. By using the hybrid nanogenerator to scavenge the vibrational energy produced by human hands, a temperature-humidity sensor can be sustainably powered by the nanogenerator, which is capable of charging the 200 ~F system power capacitor from 0 to 2 V in 15 s, and sustainably power the sensor in 29 s.

Self-powered versatile shoes based on hybrid nanogenerators

A triboelectric nanogenerator （TENG） and an electromagnetic generator （EMG） were hybridized to harvest the human mechanical energy. By an effective conjunction of triboelectrificafion and electromagnetic induction, the hybridized nanogenerator with a radius of 2 cm and height of 1.2 cm could charge a 1,000 bkF capacitor to 5.09 V after 100 cycles of vibration. This mini-sized hybrid nanogenerator could then be embedded in shoes to serve as an energy cell. Typical outdoor applications--including driving with a Global Positioning System （GPS） device, charging a Li-ion battery and a cell phone--were successfully demonstrated, suggesting its potential application in smart wearable electronics and future suits of soldiers.

Recent progress on flexible nanogenerators toward self-powered systems

The advances in wearable/flexible electronics have triggered tremendous demands for flexible power sources,where flexible nanogenerators,capable of converting mechanical energy into electricity,demonstrate its great potential.Here,recent progress on flexible nanogenerators for mechanical energy harvesting toward self-powered systems,including flexible piezoelectric and triboelectric nanogenerator,is reviewed.The emphasis is mainly on the basic working principle,the newly developed materials and structural design as well as associated typical applications for energy harvesting,sensing,and selfpowered systems.In addition,the progress of flexible hybrid nanogenerator in terms of its applications is also highlighted.Finally,the challenges and future perspectives toward flexible self-powered systems are reviewed.

A wearable noncontact free-rotating hybrid nanogenerator for self-powered electronics

Self-powerability is a new trend in the development of portable devices.Harvesting biomechanical energy to power personal information electronics is of great significance.In this work,we report a wearable noncontact freerotating hybrid nanogenerator(WRG),which is constituted by a triboelectric nanogenerator and an electromagnetic generator.A continuous output over 2 seconds can be achieved during one instantaneous incentive by external force,which is improved by two orders of magnitude compared to other wearable nanogenerators due to its unique mechanical energy storage design.The WRG can be integrated into shoes to generate an output energy of 14.68 mJ in each stepping,which meets the power requirements of most personal information electronics.The wireless sensor,GPS,and smartphone can be powered by the WRG continuously.The WRG is expected to be applied in self-powered information electronics extensively in the future.

Multilayered flexible nanocomposite for hybrid nano- generator enabled by conjunction of piezoelectricity and triboelectricity

We fabricate a flexible hybrid nanogenerator （HNG）, based on multilayered nanocomposite materials, which integrates a piezoelectric nanogenerator （PENG） and a triboelectric nanogenerator （TENG） into a single structure with only two electrodes. The HNG enables enhancement of the electrical output of the nano- generators. An open-circuit voltage of 280 V and a short-circuit current of 25 μA are achieved by a HNG of 2.5 cm × 2.5 cm in size, superior to the performance of previously reported HNGs. In addition, the energy-conversion process of the HNG relies on the working mechanism of both the PENG and TENG. The polarization direction and doping content of BTO are the two major factors that affect the electrical output. Biomechanical energy harvesting from walking motion or the bending of an arm is also demonstrated.

A static-dynamic energy harvester for a self-powered ocean environment monitoring application

Ocean intelligent buoy is important for ocean environment monitoring.With the increase of requisite sensors and transportable data,a long power supply has become a problem to be solved urgently.In this work,a hybrid nanogenerator integrating triboelectric,piezoelectric,electromagnetic,photovoltaic,and thermotropic units is proposed to maximize ocean ambient energy harvesting,which includes static energy(solar and thermal energy)and dynamic energy(wave energy).Compared with a device with a single energy conversion mechanism,this structural design breaks the limit of harvesting time and natural conditions during the energy harvesting process,thereby increasing the harvested energy.Static energy harvesting is realized by the thermoelectric(TG)and photovoltaic(PV)units located inside the device and the PV unit attached to the device surface.Results show that the maximum open-circuit voltage and short-circuit current are 5 V and 41 mA in the external PV and 1.33 V and 49 mA in the internal PV under 30000 Lux illumination,respectively.The open-circuit voltage and short-circuit current of the TG unit are 5 V and 15 m A,respectively.The core component of the dynamic generation unit is the gimbal used to harvest wave energy by the triboelectric nanogenerator(TENG),piezoelectric generator(PENG),and electromagnetic generator.When the frequency is 2.4 Hz,the maximum peak-to-peak power of the TENG,PENG,and EMG are 0.25,1.58,and 13.8 mW,respectively.Finally,an intelligent ocean buoy is fabricated by the integration of an energy harvester,a power management circuit,sensors,a microcontroller,and a wireless communication module.Driven by static and dynamic energy,temperature signal,humidity signal,GPS signal,and sound signal are sent to the receiving terminal wirelessly.The ocean energy harvester proposed in this work is of great significance for ocean energy harvesting and ocean wireless monitoring systems.