Two-dimensional material has been widely investigated for potential applications in sensor and flexible electronics.In this work,a self-powered flexible humidity sensing device based on poly(vinyl alcohol)/Ti_(3)C_(2)...Two-dimensional material has been widely investigated for potential applications in sensor and flexible electronics.In this work,a self-powered flexible humidity sensing device based on poly(vinyl alcohol)/Ti_(3)C_(2)Tx(PVA/MXene)nanofibers film and monolayer molybdenum diselenide(MoSe2)piezoelectric nanogenerator(PENG)was reported for the first time.The monolayer MoSe_(2)-based PENG was fabricated by atmospheric pressure chemical vapor deposition techniques,which can generate a peak output of 35 mV and a power density of42 mW m^(-2).The flexible PENG integrated on polyethylene terephthalate(PET)substrate can harvest energy generated by different parts of human body and exhibit great application prospects in wearable devices.The electrospinned PVA/MXene nanofiber-based humidity sensor with flexible PET substrate under the driven of monolayer MoSe_(2) PENG,shows high response of~40,fast response/recovery time of 0.9/6.3 s,low hysteresis of 1.8%and excellent repeatability.The self-powered flexible humidity sensor yields the capability of detecting human skin moisture and ambient humidity.This work provides a pathway to explore the high-performance humidity sensor integrated with PENG for the self-powered flexible electronic devices.展开更多
Ultra-stable piezoelectric nanogenerator(PENG)driven by environmental actuation sources with all-weather service capability is highly desirable.Here,the PENG based on N doped 4H-SiC nanohole arrays(NHAs)is proposed to...Ultra-stable piezoelectric nanogenerator(PENG)driven by environmental actuation sources with all-weather service capability is highly desirable.Here,the PENG based on N doped 4H-SiC nanohole arrays(NHAs)is proposed to harvest ambient energy under low/high temperature and relative humidity(RH)conditions.Finite element method simulation of N doped 4H-SiC NHAs in compression mode is developed to evaluate the relationship between nanohole diameter and piezoelectric performance.The density of short circuit current of the assembled PENG reaches 313 nA cm^(-2),which is 1.57 times the output of PENG based on N doped 4H-SiC nanowire arrays.The enhancement can be attributed to the existence of nanohole sidewalls in NHAs.All-weather service capability of the PENG is verified after being treated at-80/80℃and 0%/100%RH for 50 days.The PENG is promising to be widely used in practice worldwide to harvest biomechanical energy and mechanical energy.展开更多
Flexible self-powered electromechanical devices,such as piezoelectric nanogenerators(PENGs),which are used in wearable and implantable devices,are emerging as state-of-the-art clean energy sources.In this study,a scal...Flexible self-powered electromechanical devices,such as piezoelectric nanogenerators(PENGs),which are used in wearable and implantable devices,are emerging as state-of-the-art clean energy sources.In this study,a scalable supersonic spraying technique was used to prepare flexible piezocomposite films of polyvinylidene fluoride(PVDF)and hydrothermally synthesized ZnSnO_(3)(ZSO)cubes for PENGs.Raman spectra confirmed that the transformation of the α-phase of PVDF to its β-phase was induced by the shear stress generated between the ZSO particles and PVDF polymer during supersonic spraying.The op-timized sample comprising 0.43 g of ZSO cubes and 1 g of PVDF produced a maximum piezopotential of 41.5 V and a short-circuit current,I_(sc),of 52.5 μA.A maximum power density of 50.6 μW cm-2 was ob-tained at a loading resistance of 0.4 MΩ,which matched the impedance of the PENG.Long-term tapping and bending cycles of N_(tap)=4200 and N_(bend)=600 yielded piezopotentials of 40.5 and 1.7 V,respectively.In addition,electrical poling for 2 h increased the piezopotential to 52 V owing to the alignment of the ferroelectric dipoles in the PVDF.展开更多
Piezoelectric nanogenerators(PENGs)are promising for harvesting renewable and abundant mechanical energy with high efficiency.Up to now,published research studies have mainly focused on increasing the sensitivity and ...Piezoelectric nanogenerators(PENGs)are promising for harvesting renewable and abundant mechanical energy with high efficiency.Up to now,published research studies have mainly focused on increasing the sensitivity and output of PENGs.The technical challenges in relation to practicability,comfort,and antibacterial performance,which are critically important for wearable applications,have not been well addressed.To overcome the limitations,we developed an all-nanofiber PENG(ANF-PENG)with a sandwich structure,in which the middle poly(vinylidene fluoride-co-hexafluoropropylene(P(VDF-HFP))/ZnO electrospun nanofibers serve as the piezoelectric layer,and the above and below electrostatic direct-writing P(VDF-HFP)/ZnO nanofiber membranes with a 110 nm Ag layer on one side that was plated by vacuum coating technique serve as the electrode layer.As the ANF-PENG only has 91μm thick and does not need further encapsulating,it has a high air permeability of 24.97 mm/s.ZnO nanoparticles in ANF-PENG not only improve the piezoelectric output,but also have antibacterial function(over 98%).The multifunctional ANF-PENG demonstrates good sensitivity to human motion and can harvest mechanical energy,indicating great potential applications in flexible self-powered electronic wearables and body health monitoring.展开更多
Wound management is a crucial measure for skin wound healing and is significantly important to maintaining the integrity of skins and their functions.Electrical stimulation at the wound site is a compelling strategy f...Wound management is a crucial measure for skin wound healing and is significantly important to maintaining the integrity of skins and their functions.Electrical stimulation at the wound site is a compelling strategy for skin wound repair.However,there has been an urgent need for wearable and point-of-care electrical stimulation devices that have self-adhesive and mechanical properties comparable to wound tissue.Herein,we develop a bioinspired hybrid patch with self-adhesive and piezoelectric nanogenerator(HPSP)for promoting skin wound healing,which is composed of a mussel-inspired hydrogel matrix and a piezoelectric nanogenerator based on aligned electrospun poly(vinylidene fluoride)nanofibers.The device with optimized modulus and permeability for skin wear can self-adhere to the wound site and locally produce a dynamic voltage caused by motion.We show that the HPSP not only promotes fibroblast proliferation and migration in vitro,but also effectively facilitates the collagen deposition,angiogenesis,and re-epithelialization in vivo with the increased expressions of crucial growth factors.The HPSP reduces the wound closure time of full-thickness skin defects by about 1/3,greatly accelerating the healing process.This patch can serve as wearable and real-time electrical stimulation devices,potentially useful in clinical applications of skin wound healing.展开更多
Recent experiments have demonstrated that nanogenerators fabricated using two-dimensional MoS2 flakes may find potential applications in electromechanical sensing, wearable technology, pervasive computing, and implant...Recent experiments have demonstrated that nanogenerators fabricated using two-dimensional MoS2 flakes may find potential applications in electromechanical sensing, wearable technology, pervasive computing, and implanted devices. In the present study, we theoretically examined the effect of the number of atomic layers in MoS2 flakes on the nanogenerator output. Under a square-wave applied strain, MoS2 flakes with an even number of atomic layers did not exhibit a piezoelectric output, owing to the presence of a projected inversion symmetry. On the other hand, for MoS2 flakes with an odd number of layers, owing to the lack of inversion symmetry, piezoelectric output voltage and current were generated, and decreased with the increase of the number of layers. Furthermore, as MoS2 flakes were only a few atoms thick, the capacitance of the MoS2 nanogenerators was at least an order of magnitude smaller than that of the nanowire- and nanofilm-based nanogenerators, enabling the use of MoS2 nano- generators in high-frequency applications. Our results explain the experimental observations and provide guidance on optimizing and designing two-dimensional nanogenerators.展开更多
Piezoelectric nanogenerators(PENGs)that can harvest mechanical energy from ambient environment have broad prospects for multi-functional applications.Here,multi-layered piezoelectric composites with a porous structure...Piezoelectric nanogenerators(PENGs)that can harvest mechanical energy from ambient environment have broad prospects for multi-functional applications.Here,multi-layered piezoelectric composites with a porous structure based on highly oriented Pb(Zr_(0.52)Ti_(0.48))O_(3)/PVDF(PZT/PVDF)electrospinning fibers are prepared via a laminating method to construct high-performance PENGs.PZT particles as piezoelectric reinforcing phases are embedded in PVDF fibers and facilitate the formation of polarβphase in PVDF.The multi-layered,porous structure effectively promotes the overall polarization and surface bound charge density,resulting in a highly efficient electromechanical conversion.The PENG based on 10 wt%PZT/PVDF composite fibers with a 220µm film thickness outputs an optimal voltage of 62.0 V and a power of 136.9μW,which are 3.4 and 6.5 times those of 10 wt%PZT/PVDF casting film-based PENG,respectively.Importantly,the PENG shows a high sensitivity of 12.4 V·N^(−1),presenting a significant advantage in comparison to PENGs with other porous structures.In addition,the composites show excellent flexibility with a Young’s modulus of 227.2 MPa and an elongation of 262.3%.This study shows a great potential application of piezoelectric fiber composites in flexible energy harvesting devices.展开更多
This paper describes a novel strategy to weaken the piezopotential screening effect by forming Schottky junctions on the ZnO surface through the introduction of Au particles onto the surface. With this approach, the p...This paper describes a novel strategy to weaken the piezopotential screening effect by forming Schottky junctions on the ZnO surface through the introduction of Au particles onto the surface. With this approach, the piezoelectric-energyconversion performance was greatly enhanced. The output voltage and current density of the Au@ZnO nanoarray-based piezoelectric nanogenerator reached 2 V and 1 μA/cm^2, respectively, 10 times higher than the output of pristine ZnO nanoarray-based piezoelectric nanogenerators. We attribute this enhancement to dramatic suppression of the screening effect due to the decreased carrier concentration, as determined by scanning Kelvin probe microscope measurements and impedance analysis. The lowered capacitance of the Au@ZnO nanoarraybased piezoelectric nanogenerator also contributes to the improved output. This work provides a novel method to enhance the performance of piezoelectric nanogenerators and possibly extends to piezotronics and piezophototronics.展开更多
In recent years,piezoelectric nanogenerators(PENGs)have been developed as a promising energyharvesting electronic device.However,the electrodes of most PENGs devices are precious metals,thus increasing the production ...In recent years,piezoelectric nanogenerators(PENGs)have been developed as a promising energyharvesting electronic device.However,the electrodes of most PENGs devices are precious metals,thus increasing the production cost.Here,we propose a flexible transparent PENGs with polyoxometalates(POMs)as the electrodes;it can effectively utilize ambient mechanical energy to generate electricity.Five types of polyoxometalates with different structures and compositions are selected as the electrode materials for PENGs for the first time,and the output performance of different PENGs electrode devices is tested.The PENG device with(NH4)6 P2 Mo18 O62 as the electrode can steadily provide a high electric output with an open-circuit voltage of 2.8 m V and a short-circuit current of 8.5 mA at the bending degree of90°.At the same time,the transmission spectrum shows that the average visible transmittance(AVT)of PENG can reach 31%,thus outperforming the benchmark for window applications.Finally,the working mechanism,force analysis,repeatability,and stability of PENG are systematically evaluated.All the studies show that this flexible transparent device has potential application prospect in wearable electronic devices.展开更多
Piezoelectric nanogenerators(NGs)have been developed for converting mechanical energy into electric energy using ZnO,GaN,ZnSnO3,and PZT nanowires.Due to the unique polarity and non-central symmetry of the wurtzite str...Piezoelectric nanogenerators(NGs)have been developed for converting mechanical energy into electric energy using ZnO,GaN,ZnSnO3,and PZT nanowires.Due to the unique polarity and non-central symmetry of the wurtzite structure,a composite made of using the conical shaped nanowires are used as a simple,cost-effective,and scalable nanogenerator.Based on the finite element methods,the output voltage of the nanogenerator is modeled numerically.The key factors:the spatial location of nanowires,length and dip angle of nanowires,thickness of NG devices,and the physical properties of the polymer inside NGs,which affect the output voltage are studied.The results provide guidance for optimization the output of piezoelectric nanogenerators.展开更多
With the arrival of the era of artificial intelligence(AI)and big data,the explosive growth of data has raised higher demands on computer hardware and systems.Neuromorphic techniques inspired by biological nervous sys...With the arrival of the era of artificial intelligence(AI)and big data,the explosive growth of data has raised higher demands on computer hardware and systems.Neuromorphic techniques inspired by biological nervous systems are expected to be one of the approaches to breaking the von Neumann bottleneck.Piezotronic neuromorphic devices modulate electrical transport characteristics by piezopotential and directly associate external mechanical motion with electrical output signals in an active manner,with the capability to sense/store/process information of external stimuli.In this review,we have presented the piezotronic neuromorphic devices(which are classified into strain-gated piezotronic transistors and piezoelectric nanogenerator-gated field effect transistors based on device structure)and discussed their operating mechanisms and related manufacture techniques.Secondly,we summarized the research progress of piezotronic neuromorphic devices in recent years and provided a detailed discussion on multifunctional applications,including bionic sensing,information storage,logic computing,and electrical/optical artificial synapses.Finally,in the context of future development,challenges,and perspectives,we have discussed how to modulate novel neuromorphic devices with piezotronic effects more effectively.It is believed that the piezotronic neuromorphic devices have great potential for the next generation of interactive sensation/memory/computation to facilitate the development of the Internet of Things,AI,biomedical engineering,etc.展开更多
Piezoelectricity is the electric charge which accumulates in certain materials in response to mechanical stimuli,while piezoelectric nanogenerators(PENGs)converting mechanical energy into electricity can be widely use...Piezoelectricity is the electric charge which accumulates in certain materials in response to mechanical stimuli,while piezoelectric nanogenerators(PENGs)converting mechanical energy into electricity can be widely used for energy harvesting and self-powered systems.The group IV-VI monochalcogenides may exhibit strong piezoelectricity because of their puckered C_(2v)symmetry and electronic structure,making them promising for flexible PENG.Herein,we investigated the synthesis and piezoelectric properties of multilayer SnSe nanosheets grown by chemical vapor deposition(CVD).The SnSe nanosheets exhibited high single-crystallinity,large area,and good stability.The strong layer-dependent in-plane piezoelectric coefficient of SnSe nanosheets showed a saturated trend to be~110 pm/V,which overcomes the weak piezoelectric response or odd-even effects in other layered nanosheets.A high energy conversion efficiency of 9.3%and a maximum power density of 538 mW/cm^(2)at 1.03%strain have been demonstrated in a SnSe-based PENG.Based on the enhanced piezoelectricity of SnSe and attractive output performance of the nanogenerator,a self-powered sensor for human motion monitoring is further developed.These results demonstrate the strong piezoelectricity in high quality CVD-grown SnSe nanosheets,allowing for application in flexible smart piezoelectric sensors and advanced microelectromechanical devices.展开更多
Energy harvesting plays a crucial role in modern society.In the past years,solar energy,owing to its renewable,green,and infinite attributes,has attracted increasing attention across a broad range of applications from...Energy harvesting plays a crucial role in modern society.In the past years,solar energy,owing to its renewable,green,and infinite attributes,has attracted increasing attention across a broad range of applications from small-scale wearable electronics to large-scale energy powering.However,the utility of solar cells in providing a stable power supply for vari-ous electrical appliances in practical applications is restricted by weather conditions.To address this issue,researchers have made many efforts to integrate solar cells with other types of energy harvesters,thus developing hybrid energy har-vesters(HEHs),which can harvest energy from the ambient environment via different working mechanisms.In this re-view,four categories of energy harvesters including solar cells,triboelectric nanogenerators(TENGs),piezoelectric nanogenerators(PENGs),and thermoelectric generators(TEGs)are introduced.In addition,we systematically summar-ize the recent progress in solar cell-based hybrid energy harvesters(SCHEHs)with a focus on their structure designs and the corresponding applications.Three hybridization designs through unique combinations of TENG,PENG,and TEG with solar cells are elaborated in detail.Finally,the main challenges and perspectives for the future development of SCHEHs are discussed.展开更多
The utilization of piezoelectric nanogenerator(PENG)based on halide perovskite materials has demonstrated significant promise for energy harvesting applications.However,the challenge of synthesizing halide perovskite ...The utilization of piezoelectric nanogenerator(PENG)based on halide perovskite materials has demonstrated significant promise for energy harvesting applications.However,the challenge of synthesizing halide perovskite materials with both high output performance and stability using a straightforward process persists as a substantial obstacle.Herein,we present the fabrication of CsPbI_(3) nanorods(NRs)exhibiting highly uniform orientation within polyvinylidene fluoride(PVDF)fibers through a simple texture engineering approach,marking the instance of enhancing PENG performance in this manner.The resultant composite fibers showcase a short-circuit current density(I_(sc))of 0.78μAcm^(-2) and an open-circuit voltage(V_(oc)) of 81V,representing a 2.5 fold increase compared to the previously reported highest value achieved without the electric poling process.This outstanding output performance is ascribed to the orientation of CsPbI_(3) NRs facilitated by texture engineering and dipole poling via the self-polarization effect.Additionally,the PENG exhibits exceptional thermal and water stability,rendering it suitable for deployment in diverse and challenging environmental conditions.Our findings underscore the significant potential of textured CsPbI_(3) NRs composite fibers for powering low-power consumer electronics,including commercial LEDs and electronic watches.展开更多
Nanofibrous acoustic energy harvesters(NAEHs)have emerged as promising wearable platforms for efficient noise-to-electricity conversion in distributed power energy systems and wearable sound amplifiers for assistive l...Nanofibrous acoustic energy harvesters(NAEHs)have emerged as promising wearable platforms for efficient noise-to-electricity conversion in distributed power energy systems and wearable sound amplifiers for assistive listening devices.However,their reallife efficacy is hampered by low power output,particularly in the low-frequency range(<1 kHz).This study introduces a novel approach to enhance the performance of NAEHs by applying machine learning(ML)techniques to guide the synthesis of electrospun polyvinylidene fluoride(PVDF)/polyurethane(PU)nanofibers,optimizing their application in wearable NAEHs.We use a feed-forward neural network along with solving an optimization problem to find the optimal input values of the electrospinning(applied voltage,nozzle-collector distance,electrospinning time,and drum rotation speed)to generate maximum output performance(acoustic-to-electricity conversion efficiency).We first prepared a dataset to train the network to predict the output power given the input variables with high accuracy.Upon introducing the neural network,we fix the network and then solve an optimization problem using a genetic algorithm to search for the input values that lead to the maximum energy harvesting efficiency.Our ML-guided wearable PVDF/PU NAEH platform can deliver a maximal acoustoelectric power density output of 829μW/cm^(3) within the surrounding noise levels.In addition,our system can function stably in a broad frequency(0.1-2 kHz)with a high energy conversion efficiency of 66%.Sound recognition analysis reveals a robust correlation exceeding 0.85 among lexically akin terms with varying sound intensities,contrasting with a diminished correlation below 0.27 for words with disparate semantic connotations.Overall,this work provides a previously unexplored route to utilize ML in advancing wearable NAEHs with excellent practicability.展开更多
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 p...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.展开更多
The combination of new intelligent materials and structure technology is becoming an effective way in energy havesting and self-powered sensing. In this work, we demonstrate a magnetically levitated/piezoelectric/trib...The combination of new intelligent materials and structure technology is becoming an effective way in energy havesting and self-powered sensing. In this work, we demonstrate a magnetically levitated/piezoelectric/triboelectric hybrid generator, which does not use complex structure and has high steady output performance. It includes three parts: magnetically levitated generator(MLG), piezoelectric generator(PNG), triboelectric nanogenerator(TENG). The peak power of each is 135 μW, 22 mW and3.6 mW, which are obtained at 1 MΩ, 10 kΩ and 1 kΩ, respectively. The hybrid generator can completely light up light-emitting diodes(LEDs) under the vibration frequency of 20 Hz and the vibration amplitude of 10 mm. It also can charge a 470 μF capacitor.On this basis, we have integrated the hybrid generaor as a power supply into a self-powered tempreature sensing system. The combination of three generators can not only broaden the operating range, but also increase the operating length and sensitivity.This work will extend the application of self-powered sensor in automatic production line and promote the development of industrial control technology.展开更多
Monitoring various medical information distributed throughout the body is of great importance in early clinic diagnosis and treatment of disease.To discover abnormal medical signals and find their causes in good time,...Monitoring various medical information distributed throughout the body is of great importance in early clinic diagnosis and treatment of disease.To discover abnormal medical signals and find their causes in good time,the human body should be monitored continuously and accurately.To meet the requirements,various battery-less and self-powered information acquisition techniques are invented.In this review,the recent advances in self-powered medical information sensors(SMIS)with different functions,structure design,and electric performance are summarized and discussed.The SMIS mainly involves triboelectric nanogenerator(TENG),piezoelectric nanogenerator(PENG),pyroelectric nanogenerator(PyNG)/thermoelectric generator(TEG)and solar cell.Additionally,this review also analyzed the remaining challenges and prospected the development direction of SMIS in future.展开更多
基金supported by the National Natural Science Foundation of China(51777215)National Natural Science Foundation of China(51775306)+1 种基金Beijing Municipal Natural Science Foundation(4192027)the Graduate Innovation Fund of China University of Petroleum(YCX2020097)。
文摘Two-dimensional material has been widely investigated for potential applications in sensor and flexible electronics.In this work,a self-powered flexible humidity sensing device based on poly(vinyl alcohol)/Ti_(3)C_(2)Tx(PVA/MXene)nanofibers film and monolayer molybdenum diselenide(MoSe2)piezoelectric nanogenerator(PENG)was reported for the first time.The monolayer MoSe_(2)-based PENG was fabricated by atmospheric pressure chemical vapor deposition techniques,which can generate a peak output of 35 mV and a power density of42 mW m^(-2).The flexible PENG integrated on polyethylene terephthalate(PET)substrate can harvest energy generated by different parts of human body and exhibit great application prospects in wearable devices.The electrospinned PVA/MXene nanofiber-based humidity sensor with flexible PET substrate under the driven of monolayer MoSe_(2) PENG,shows high response of~40,fast response/recovery time of 0.9/6.3 s,low hysteresis of 1.8%and excellent repeatability.The self-powered flexible humidity sensor yields the capability of detecting human skin moisture and ambient humidity.This work provides a pathway to explore the high-performance humidity sensor integrated with PENG for the self-powered flexible electronic devices.
基金This work was supported by the National Science Fund for Distinguished Young Scholars(No.52025041)the National Natural Science Foundation of China(No.51974021,51902020,51904021)+2 种基金the Fundamental Research Funds for the Central Universities of NO.FRF-TP-18-045A1 and FRF-TP-19-004B2Zthe National Postdoctoral Program for Innovative Talents(BX20180034)This project is supported by open foundation of Guangxi Key Laboratory of Processing for Non-ferrous Metals and Featured Materials,Guangxi University(Grant No.2021GXYSOF12).
文摘Ultra-stable piezoelectric nanogenerator(PENG)driven by environmental actuation sources with all-weather service capability is highly desirable.Here,the PENG based on N doped 4H-SiC nanohole arrays(NHAs)is proposed to harvest ambient energy under low/high temperature and relative humidity(RH)conditions.Finite element method simulation of N doped 4H-SiC NHAs in compression mode is developed to evaluate the relationship between nanohole diameter and piezoelectric performance.The density of short circuit current of the assembled PENG reaches 313 nA cm^(-2),which is 1.57 times the output of PENG based on N doped 4H-SiC nanowire arrays.The enhancement can be attributed to the existence of nanohole sidewalls in NHAs.All-weather service capability of the PENG is verified after being treated at-80/80℃and 0%/100%RH for 50 days.The PENG is promising to be widely used in practice worldwide to harvest biomechanical energy and mechanical energy.
基金National Research Foundation of Korea(NRF)Grant funded by the Korea government(MSIT)(Nos.NRF-2020R1A5A1018153 and 2022M3J1A106422611)The authors acknowledge King Saud University,Riyadh,Saudi Arabia,for funding this work through Researchers Supporting Project number(No.RSP2023R30).
文摘Flexible self-powered electromechanical devices,such as piezoelectric nanogenerators(PENGs),which are used in wearable and implantable devices,are emerging as state-of-the-art clean energy sources.In this study,a scalable supersonic spraying technique was used to prepare flexible piezocomposite films of polyvinylidene fluoride(PVDF)and hydrothermally synthesized ZnSnO_(3)(ZSO)cubes for PENGs.Raman spectra confirmed that the transformation of the α-phase of PVDF to its β-phase was induced by the shear stress generated between the ZSO particles and PVDF polymer during supersonic spraying.The op-timized sample comprising 0.43 g of ZSO cubes and 1 g of PVDF produced a maximum piezopotential of 41.5 V and a short-circuit current,I_(sc),of 52.5 μA.A maximum power density of 50.6 μW cm-2 was ob-tained at a loading resistance of 0.4 MΩ,which matched the impedance of the PENG.Long-term tapping and bending cycles of N_(tap)=4200 and N_(bend)=600 yielded piezopotentials of 40.5 and 1.7 V,respectively.In addition,electrical poling for 2 h increased the piezopotential to 52 V owing to the alignment of the ferroelectric dipoles in the PVDF.
基金The authors acknowledge the financial support from the National Natural Science Foundation of China(No.52073224)Textile Vision Basic Research Program of China(No.J202110)+3 种基金Advanced manufacturing technology project of Xi’an Science and Technology Bureau,China(21XJZZ0019)Scientific Research Project of Shaanxi Provincial Education Department,China(No.22JC035)Key Research and Development Program of Xianyang Science and Technology Bureau,China(No.2021ZDYF-GY-0035)Research Fund for the Doctoral Program of Xi’an Polytechnic University(No.BS202006).
文摘Piezoelectric nanogenerators(PENGs)are promising for harvesting renewable and abundant mechanical energy with high efficiency.Up to now,published research studies have mainly focused on increasing the sensitivity and output of PENGs.The technical challenges in relation to practicability,comfort,and antibacterial performance,which are critically important for wearable applications,have not been well addressed.To overcome the limitations,we developed an all-nanofiber PENG(ANF-PENG)with a sandwich structure,in which the middle poly(vinylidene fluoride-co-hexafluoropropylene(P(VDF-HFP))/ZnO electrospun nanofibers serve as the piezoelectric layer,and the above and below electrostatic direct-writing P(VDF-HFP)/ZnO nanofiber membranes with a 110 nm Ag layer on one side that was plated by vacuum coating technique serve as the electrode layer.As the ANF-PENG only has 91μm thick and does not need further encapsulating,it has a high air permeability of 24.97 mm/s.ZnO nanoparticles in ANF-PENG not only improve the piezoelectric output,but also have antibacterial function(over 98%).The multifunctional ANF-PENG demonstrates good sensitivity to human motion and can harvest mechanical energy,indicating great potential applications in flexible self-powered electronic wearables and body health monitoring.
基金We thank the funding support from the National Natural Science Foundation of China(Nos.51973075 and 51525302)Program for HUST Academic Frontier Youth Team(2015-01)The authors thank HUST Analytical and Testing Center for their supports on the facilities.
文摘Wound management is a crucial measure for skin wound healing and is significantly important to maintaining the integrity of skins and their functions.Electrical stimulation at the wound site is a compelling strategy for skin wound repair.However,there has been an urgent need for wearable and point-of-care electrical stimulation devices that have self-adhesive and mechanical properties comparable to wound tissue.Herein,we develop a bioinspired hybrid patch with self-adhesive and piezoelectric nanogenerator(HPSP)for promoting skin wound healing,which is composed of a mussel-inspired hydrogel matrix and a piezoelectric nanogenerator based on aligned electrospun poly(vinylidene fluoride)nanofibers.The device with optimized modulus and permeability for skin wear can self-adhere to the wound site and locally produce a dynamic voltage caused by motion.We show that the HPSP not only promotes fibroblast proliferation and migration in vitro,but also effectively facilitates the collagen deposition,angiogenesis,and re-epithelialization in vivo with the increased expressions of crucial growth factors.The HPSP reduces the wound closure time of full-thickness skin defects by about 1/3,greatly accelerating the healing process.This patch can serve as wearable and real-time electrical stimulation devices,potentially useful in clinical applications of skin wound healing.
基金This work was supported by the ＂Thousands Talents＂ Program for Pioneer Team, China, and Researcher and his Innovation the National Natural Science Foundation of China （No. 51432005）
文摘Recent experiments have demonstrated that nanogenerators fabricated using two-dimensional MoS2 flakes may find potential applications in electromechanical sensing, wearable technology, pervasive computing, and implanted devices. In the present study, we theoretically examined the effect of the number of atomic layers in MoS2 flakes on the nanogenerator output. Under a square-wave applied strain, MoS2 flakes with an even number of atomic layers did not exhibit a piezoelectric output, owing to the presence of a projected inversion symmetry. On the other hand, for MoS2 flakes with an odd number of layers, owing to the lack of inversion symmetry, piezoelectric output voltage and current were generated, and decreased with the increase of the number of layers. Furthermore, as MoS2 flakes were only a few atoms thick, the capacitance of the MoS2 nanogenerators was at least an order of magnitude smaller than that of the nanowire- and nanofilm-based nanogenerators, enabling the use of MoS2 nano- generators in high-frequency applications. Our results explain the experimental observations and provide guidance on optimizing and designing two-dimensional nanogenerators.
基金The authors gratefully acknowledge the financial support from the National Natural Science Foundation of China(No.51772267)the Key R&D Program of Zhejiang Province(No.2020C01004).
文摘Piezoelectric nanogenerators(PENGs)that can harvest mechanical energy from ambient environment have broad prospects for multi-functional applications.Here,multi-layered piezoelectric composites with a porous structure based on highly oriented Pb(Zr_(0.52)Ti_(0.48))O_(3)/PVDF(PZT/PVDF)electrospinning fibers are prepared via a laminating method to construct high-performance PENGs.PZT particles as piezoelectric reinforcing phases are embedded in PVDF fibers and facilitate the formation of polarβphase in PVDF.The multi-layered,porous structure effectively promotes the overall polarization and surface bound charge density,resulting in a highly efficient electromechanical conversion.The PENG based on 10 wt%PZT/PVDF composite fibers with a 220µm film thickness outputs an optimal voltage of 62.0 V and a power of 136.9μW,which are 3.4 and 6.5 times those of 10 wt%PZT/PVDF casting film-based PENG,respectively.Importantly,the PENG shows a high sensitivity of 12.4 V·N^(−1),presenting a significant advantage in comparison to PENGs with other porous structures.In addition,the composites show excellent flexibility with a Young’s modulus of 227.2 MPa and an elongation of 262.3%.This study shows a great potential application of piezoelectric fiber composites in flexible energy harvesting devices.
基金This work was supported by the National Basic Research Program of China （No. 2013CB932602）, the Program of Introducing Talents of Discipline to Universities （No. B14003）, National Natural Science Foundation of China （Nos. 51527802 and 51232001）,Beijing Municipal Science ＆ Technology Commission, the Fundamental Research Funds for Central Universities.
文摘This paper describes a novel strategy to weaken the piezopotential screening effect by forming Schottky junctions on the ZnO surface through the introduction of Au particles onto the surface. With this approach, the piezoelectric-energyconversion performance was greatly enhanced. The output voltage and current density of the Au@ZnO nanoarray-based piezoelectric nanogenerator reached 2 V and 1 μA/cm^2, respectively, 10 times higher than the output of pristine ZnO nanoarray-based piezoelectric nanogenerators. We attribute this enhancement to dramatic suppression of the screening effect due to the decreased carrier concentration, as determined by scanning Kelvin probe microscope measurements and impedance analysis. The lowered capacitance of the Au@ZnO nanoarraybased piezoelectric nanogenerator also contributes to the improved output. This work provides a novel method to enhance the performance of piezoelectric nanogenerators and possibly extends to piezotronics and piezophototronics.
基金supported by the National Natural Science Foundation of China (21871041, 21801038, and 21771095)the Natural Science Foundation of Jilin Province (20180101298JC), the Talent Development Foundation of Jilin Province+4 种基金the China Postdoctoral Science Foundation, China funded project (2018M630312, 2019T120227)the Fundamental Research Funds for the Central Universities, China (2412018QD003)the Technology Foundation for Selected Overseas Chinese Scholars of Personnel Ministry of China, ChinaScience and Technology Activities Project Preferential Funding for Selected Overseas Chinese Scholars of Jilin Province Human Resources and Social Bureau, Chinathe Science and Technology Research Foundation of the Thirteenth Five Years of Jilin Educational Committee, China (JJKH20190271KJ)
文摘In recent years,piezoelectric nanogenerators(PENGs)have been developed as a promising energyharvesting electronic device.However,the electrodes of most PENGs devices are precious metals,thus increasing the production cost.Here,we propose a flexible transparent PENGs with polyoxometalates(POMs)as the electrodes;it can effectively utilize ambient mechanical energy to generate electricity.Five types of polyoxometalates with different structures and compositions are selected as the electrode materials for PENGs for the first time,and the output performance of different PENGs electrode devices is tested.The PENG device with(NH4)6 P2 Mo18 O62 as the electrode can steadily provide a high electric output with an open-circuit voltage of 2.8 m V and a short-circuit current of 8.5 mA at the bending degree of90°.At the same time,the transmission spectrum shows that the average visible transmittance(AVT)of PENG can reach 31%,thus outperforming the benchmark for window applications.Finally,the working mechanism,force analysis,repeatability,and stability of PENG are systematically evaluated.All the studies show that this flexible transparent device has potential application prospect in wearable electronic devices.
文摘Piezoelectric nanogenerators(NGs)have been developed for converting mechanical energy into electric energy using ZnO,GaN,ZnSnO3,and PZT nanowires.Due to the unique polarity and non-central symmetry of the wurtzite structure,a composite made of using the conical shaped nanowires are used as a simple,cost-effective,and scalable nanogenerator.Based on the finite element methods,the output voltage of the nanogenerator is modeled numerically.The key factors:the spatial location of nanowires,length and dip angle of nanowires,thickness of NG devices,and the physical properties of the polymer inside NGs,which affect the output voltage are studied.The results provide guidance for optimization the output of piezoelectric nanogenerators.
基金financially supported by the National Natural Science Foundation of China(52073031,22008151)the National Key Research and Development Program of China(2021YFB3200304)+2 种基金Beijing Nova Program(Z211100002121148)Fundamental Research Funds for the Central Universities(E0EG6801X2)the‘Hundred Talents Program’of the Chinese Academy of Sciences。
文摘With the arrival of the era of artificial intelligence(AI)and big data,the explosive growth of data has raised higher demands on computer hardware and systems.Neuromorphic techniques inspired by biological nervous systems are expected to be one of the approaches to breaking the von Neumann bottleneck.Piezotronic neuromorphic devices modulate electrical transport characteristics by piezopotential and directly associate external mechanical motion with electrical output signals in an active manner,with the capability to sense/store/process information of external stimuli.In this review,we have presented the piezotronic neuromorphic devices(which are classified into strain-gated piezotronic transistors and piezoelectric nanogenerator-gated field effect transistors based on device structure)and discussed their operating mechanisms and related manufacture techniques.Secondly,we summarized the research progress of piezotronic neuromorphic devices in recent years and provided a detailed discussion on multifunctional applications,including bionic sensing,information storage,logic computing,and electrical/optical artificial synapses.Finally,in the context of future development,challenges,and perspectives,we have discussed how to modulate novel neuromorphic devices with piezotronic effects more effectively.It is believed that the piezotronic neuromorphic devices have great potential for the next generation of interactive sensation/memory/computation to facilitate the development of the Internet of Things,AI,biomedical engineering,etc.
基金supported by the grants from Research Grants Council of Hong Kong(Nos.GRF PolyU 153025/19P,SRFS2122-5S02,and AoE/P-701/20)PolyU Otto Poon Charitable Foundation Research Institute for Smart Energy(No.Q-CDBD).
文摘Piezoelectricity is the electric charge which accumulates in certain materials in response to mechanical stimuli,while piezoelectric nanogenerators(PENGs)converting mechanical energy into electricity can be widely used for energy harvesting and self-powered systems.The group IV-VI monochalcogenides may exhibit strong piezoelectricity because of their puckered C_(2v)symmetry and electronic structure,making them promising for flexible PENG.Herein,we investigated the synthesis and piezoelectric properties of multilayer SnSe nanosheets grown by chemical vapor deposition(CVD).The SnSe nanosheets exhibited high single-crystallinity,large area,and good stability.The strong layer-dependent in-plane piezoelectric coefficient of SnSe nanosheets showed a saturated trend to be~110 pm/V,which overcomes the weak piezoelectric response or odd-even effects in other layered nanosheets.A high energy conversion efficiency of 9.3%and a maximum power density of 538 mW/cm^(2)at 1.03%strain have been demonstrated in a SnSe-based PENG.Based on the enhanced piezoelectricity of SnSe and attractive output performance of the nanogenerator,a self-powered sensor for human motion monitoring is further developed.These results demonstrate the strong piezoelectricity in high quality CVD-grown SnSe nanosheets,allowing for application in flexible smart piezoelectric sensors and advanced microelectromechanical devices.
基金We are grateful for financial support from the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)via Germany’s Excellence Strategy-EXC 2089/1-390776260(e-conversion)and via the International Research Training Group 2022 the Alberta/Technical University of Munich International Graduate School for Environmentally Responsible Functional Materials(ATUMS),TUM.
文摘Energy harvesting plays a crucial role in modern society.In the past years,solar energy,owing to its renewable,green,and infinite attributes,has attracted increasing attention across a broad range of applications from small-scale wearable electronics to large-scale energy powering.However,the utility of solar cells in providing a stable power supply for vari-ous electrical appliances in practical applications is restricted by weather conditions.To address this issue,researchers have made many efforts to integrate solar cells with other types of energy harvesters,thus developing hybrid energy har-vesters(HEHs),which can harvest energy from the ambient environment via different working mechanisms.In this re-view,four categories of energy harvesters including solar cells,triboelectric nanogenerators(TENGs),piezoelectric nanogenerators(PENGs),and thermoelectric generators(TEGs)are introduced.In addition,we systematically summar-ize the recent progress in solar cell-based hybrid energy harvesters(SCHEHs)with a focus on their structure designs and the corresponding applications.Three hybridization designs through unique combinations of TENG,PENG,and TEG with solar cells are elaborated in detail.Finally,the main challenges and perspectives for the future development of SCHEHs are discussed.
基金This work was supported by the National Science Fund for Distinguished Young Scholars(No.52025041)the National Natural Science Foundation of China(Nos.51974021,51902020,52250091)+2 种基金the Fundamental Research Funds for the Central Universities(NO.FRF-TP-20-02C2)the open foundation of Guangxi Key Laboratory of Processing for Non-ferrous Metals and Featured Materials,Guangxi University(No.2021GXYSOF12)the Interdisciplinary Research Project for Young Teachers of USTB(Fundamental Research Funds for the Central Universities,FRF-IDRY-21-028).
文摘The utilization of piezoelectric nanogenerator(PENG)based on halide perovskite materials has demonstrated significant promise for energy harvesting applications.However,the challenge of synthesizing halide perovskite materials with both high output performance and stability using a straightforward process persists as a substantial obstacle.Herein,we present the fabrication of CsPbI_(3) nanorods(NRs)exhibiting highly uniform orientation within polyvinylidene fluoride(PVDF)fibers through a simple texture engineering approach,marking the instance of enhancing PENG performance in this manner.The resultant composite fibers showcase a short-circuit current density(I_(sc))of 0.78μAcm^(-2) and an open-circuit voltage(V_(oc)) of 81V,representing a 2.5 fold increase compared to the previously reported highest value achieved without the electric poling process.This outstanding output performance is ascribed to the orientation of CsPbI_(3) NRs facilitated by texture engineering and dipole poling via the self-polarization effect.Additionally,the PENG exhibits exceptional thermal and water stability,rendering it suitable for deployment in diverse and challenging environmental conditions.Our findings underscore the significant potential of textured CsPbI_(3) NRs composite fibers for powering low-power consumer electronics,including commercial LEDs and electronic watches.
基金supported by Amirkabir University of Technology and the Terasaki Institute for Biomedical Innovationsupported by the U.S.DOE,Office of Science,Basic Energy Sciences,Materials Sciences and Engineering Division.
文摘Nanofibrous acoustic energy harvesters(NAEHs)have emerged as promising wearable platforms for efficient noise-to-electricity conversion in distributed power energy systems and wearable sound amplifiers for assistive listening devices.However,their reallife efficacy is hampered by low power output,particularly in the low-frequency range(<1 kHz).This study introduces a novel approach to enhance the performance of NAEHs by applying machine learning(ML)techniques to guide the synthesis of electrospun polyvinylidene fluoride(PVDF)/polyurethane(PU)nanofibers,optimizing their application in wearable NAEHs.We use a feed-forward neural network along with solving an optimization problem to find the optimal input values of the electrospinning(applied voltage,nozzle-collector distance,electrospinning time,and drum rotation speed)to generate maximum output performance(acoustic-to-electricity conversion efficiency).We first prepared a dataset to train the network to predict the output power given the input variables with high accuracy.Upon introducing the neural network,we fix the network and then solve an optimization problem using a genetic algorithm to search for the input values that lead to the maximum energy harvesting efficiency.Our ML-guided wearable PVDF/PU NAEH platform can deliver a maximal acoustoelectric power density output of 829μW/cm^(3) within the surrounding noise levels.In addition,our system can function stably in a broad frequency(0.1-2 kHz)with a high energy conversion efficiency of 66%.Sound recognition analysis reveals a robust correlation exceeding 0.85 among lexically akin terms with varying sound intensities,contrasting with a diminished correlation below 0.27 for words with disparate semantic connotations.Overall,this work provides a previously unexplored route to utilize ML in advancing wearable NAEHs with excellent practicability.
基金This work is supported by HKSAR The Research Grants Council Early Career Scheme(Grant no.24206919)HKSAR Innovation and Technology Support Programme Tier 3(Grant no.ITS/085/18)+2 种基金The Chinese University of Hong Kong Direct Grant(Grant no.4055086)Shun Hing Institute of Advanced Engineering(Grant no.RNE-p5-18)City University of Hong Kong(Grant No.9610423).
文摘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.
基金supported by the National Natural Science Foundation of China(Grant Nos.61525107,51422510&51605449)the National High Technology Research and Development Program of China(Grant No.2015AA042601)
文摘The combination of new intelligent materials and structure technology is becoming an effective way in energy havesting and self-powered sensing. In this work, we demonstrate a magnetically levitated/piezoelectric/triboelectric hybrid generator, which does not use complex structure and has high steady output performance. It includes three parts: magnetically levitated generator(MLG), piezoelectric generator(PNG), triboelectric nanogenerator(TENG). The peak power of each is 135 μW, 22 mW and3.6 mW, which are obtained at 1 MΩ, 10 kΩ and 1 kΩ, respectively. The hybrid generator can completely light up light-emitting diodes(LEDs) under the vibration frequency of 20 Hz and the vibration amplitude of 10 mm. It also can charge a 470 μF capacitor.On this basis, we have integrated the hybrid generaor as a power supply into a self-powered tempreature sensing system. The combination of three generators can not only broaden the operating range, but also increase the operating length and sensitivity.This work will extend the application of self-powered sensor in automatic production line and promote the development of industrial control technology.
基金National Key R&D Project from Minister of Science and Technology,Grant/Award Number:2016YFA0202703National Natural Science Foundation of China,Grant/Award Numbers:21801019,31571006,61875015,81601629。
文摘Monitoring various medical information distributed throughout the body is of great importance in early clinic diagnosis and treatment of disease.To discover abnormal medical signals and find their causes in good time,the human body should be monitored continuously and accurately.To meet the requirements,various battery-less and self-powered information acquisition techniques are invented.In this review,the recent advances in self-powered medical information sensors(SMIS)with different functions,structure design,and electric performance are summarized and discussed.The SMIS mainly involves triboelectric nanogenerator(TENG),piezoelectric nanogenerator(PENG),pyroelectric nanogenerator(PyNG)/thermoelectric generator(TEG)and solar cell.Additionally,this review also analyzed the remaining challenges and prospected the development direction of SMIS in future.
