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Air-stable synaptic devices based on bismuth triiodide and carbon nanotubes

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Nano Research 2022年第6期15卷 5435-5442页

作者： Dandan Hao Junyao Zhang Li Li Ben Yang Pu Guo Shiqi Zhang Jia Huang Interdisciplinary Materials Research Center School of Materials Science and EngineeringFrontiers Science Center for Intelligent Autonomous SystemsTongji UniversityShanghai 201804China Translational Research Institute of Brain and Brain-Like Intelligence Shanghai Fourth People’s Hospital Affiliated to Tongji UniversitySchool of Materials Science and EngineeringTongji UniversityShanghai 200434China

Artificial synaptic devices with the functions of emulating important biological synaptic behaviors are playing an increasingly important role in the development of neuromorphic computing systems.Single-walled carbon nanotubes(SWCNTs)with excellent electrical properties and high stability have been studied as active materials for synaptic devices.However,the performance of optical synaptic devices(OSDs)based on pure SWCNTs is limited by the weak light absorption property.Herein,bismuth triiodide(BiI_(3)),an environmentally stable and friendly optoelectronic material,is firstly combined with SWCNTs to fabricate OSDs with decent properties of perceiving and memorizing optical information.The OSDs can exhibit typical synaptic behaviors including excitatory postsynaptic current,paired-pulse facilitation,and short/long-term memory.Distinctively,the photoresponse of the OSD is independent of pulse light wavelength in the range of 365 to 650 nm,different from most of the previously reported OSDs,which usually have wavelength-dependent photo-response.Temperature-dependent photo-response behaviors of the devices are investigated.Importantly,the OSD without encapsulation holds good excitatory post-synaptic current(EPSC)behavior after being stored in the ambient environment for 170 days,indicating reliable environmental stability.Furthermore,an OSD array with nine synaptic devices is employed to mimic the human visual perception and memory functions.These results suggest the feasibility of BiI3/SWCNTs-based OSDs for the simulation of human visual memory.

关键词： semiconducting single-walled carbon nanotubes bismuth triiodide optical synaptic devices stability human visual memory

Ultralight Iontronic Triboelectric Mechanoreceptor with High Specific Outputs for Epidermal Electronics

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Nano-Micro Letters 2022年第6期14卷 1-14页

作者： Hai Lu Wang Zi Hao guo Xiong pu Zhong Lin Wang Beijing Institute of Nanoenergy and Nanosystems Chinese Academy of SciencesBeijing 101400People’s Republic of China School of Nanoscience and Technology University of Chinese Academy of SciencesBeijing 100049People’s Republic of China Center on Nanoenergy Research School of Physical Science and TechnologyGuangxi UniversityNanning 530004People’s Republic of China CUSTech Institute of Technology Wenzhou 325024ZhejiangPeople’s Republic of China School of Materials Science and Engineering Georgia Institute of TechnologyAtlantaGA 30332USA

The pursuit to mimic skin exteroceptive ability has motivated the endeavors for epidermal artificial mechanoreceptors.Artificial mechanoreceptors are required to be highly sensitive to capture imperceptible skin deformations and preferably to be self-powered,breathable,lightweight and deformable to satisfy the prolonged wearing demands.It is still struggling to achieve these traits in single device,as it remains difficult to minimize device architecture without sacrificing the sensitivity or stability.In this article,we present an all-fiber iontronic triboelectric mechanoreceptor(ITM)to fully tackle these challenges,enabled by the high-output mechano-to-electrical energy conversion.The proposed ITM is ultralight,breathable and stretchable and is quite stable under various mechanical deformations.On the one hand,the ITM can achieve a superior instantaneous power density;on the other hand,the ITM shows excellent sensitivity serving as epidermal sensors.Precise health status monitoring is readily implemented by the ITM calibrating by detecting vital signals and physical activities of human bodies.The ITM can also realize acoustic-to-electrical conversion and distinguish voices from different people,and biometric application as a noise dosimeter is demonstrated.The ITM therefore is believed to open new sights in epidermal electronics and skin prosthesis fields.

关键词： Ultralight Iontronic Triboelectric mechanoreceptor Power density Epidermal electronics

Monolayer molecular crystals for low-energy consumption optical synaptic transistors

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Nano Research 2022年第8期15卷 7639-7645页

作者： Zhekun Hua Ben Yang Junyao Zhang Dandan Hao Pu Guo Jie Liu Lang Jiang Jia Huang Interdisciplinary Materials Research Center School of Materials Science and EngineeringFrontiers Science Center for Intelligent Autonomous SystemsTongji UniversityShanghai 201804China Beijing National Laboratory for Molecular Sciences Key Laboratory of Organic SolidsInstitute of ChemistryChinese Academy of SciencesBeijing 100190China Translational Research Institute of Brain and Brain-Like Intelligence Shanghai Fourth People's Hospital Affiliated to Tongji UniversitySchool of Materials Science and EngineeringTongji UniversityShanghai 200434China

Artificial synaptic devices hold great potential in building neuromorphic computers.Due to the unique morphological features,twodimensional organic semiconductors at the monolayer limit show interesting properties when acting as the active layers for organic field-effect transistors.Here,organic synaptic transistors are prepared with 1,4-bis((5’-hexyl-2,2’-bithiophen-5-yl)ethyl)benzene(HTEB)monolayer molecular crystals.Functions similar to biological synapses,including excitatory postsynaptic current(EPSC),pair-pulse facilitation,and short/long-term memory,have been realized.The synaptic device achieves the minimum power consumption of 4.29 fJ at low drain voltage of−0.01 V.Moreover,the HTEB synaptic device exhibits excellent long-term memory with 109 s EPSC estimated retention time.Brain-like functions such as dynamic learning-forgetting process and visual noise reduction are demonstrated by nine devices.The unique morphological features of the monolayer molecular semiconductors help to reveal the device working mechanism,and the synaptic behaviors of the devices can be attributed to oxygen induced energy level.This work shows the potential of artificial neuroelectronic devices based on organic monolayer molecular crystals.

关键词： monolayer molecular crystals synaptic devices organic field-effect transistors optical synaptic transistors

Stretchable iontronics with robust interface bonding between dielectric and ion-conducting elastomers

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Nano Research 2023年第9期16卷 11862-11870页

作者： Zhongpeng Li Panpan Zhang Yangshi Shao Zi-Hao guo Xiong pu School of Chemistry and Chemical Engineering Center on Nanoenergy ResearchSchool of Physical Science and TechnologyGuangxi UniversityNanning 530004China CAS Center for Excellence in Nanoscience Beijing Key Laboratory of Micro-Nano Energy and SensorBeijing Institute of Nanoenergy and NanosystemsChinese Academy of SciencesBeijing 101400China School of Nanoscience and Technology University of Chinese Academy of SciencesBeijing 100049China

Dry ion-conducting elastomers(ICEs)are emerging stretchable and ionic conductive materials that are demonstrated with excellent thermal stability and great promise in multifunctional iontronic devices.Nevertheless,the poor interface between the ICEs and the dielectric material is one of the issues hindering the application of the stretchable iontronic device.Herein,a polydimethylsiloxane(PDMS)based ion-conducting elastomer with dynamic crosslinking structures is reported,which achieves the stretchability of 475%and healing efficiency of 99%.More importantly,a robust interface bonding can be generated between the electrode and the dielectric material,which is beneficial to enhance the performance and lifespan of the flexible iontronic devices.Using this PDMS based ICE as the electrode and PDMS as the dielectric material,two stretchable iontronic devices(triboelectric nanogenerator and capacitive pressure sensor)are realized with overall self-healing and stretchable capabilities.These findings provide a promising strategy to achieve integrate stretchable iontronics or electronics with a robust interface between the electrode and dielectric materials.

关键词： ion-conducting elastomers robust interface iontronics triboelectric nanogenerator pressure sensor

Experimental Investigation of fluid-structure interaction of composite hydrofoils in cavitating flow

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Journal of Hydrodynamics 2022年第2期34卷 207-213页

作者： Hou-sheng Zhang Zhi-Pu Guo Qin Wu Han-zhe Zhang guo-yu Wang School of Mechanical Engineering Beijing Institute of TechnologyBeijing100081China Aviation Engineering School Air Force Engineering UniversityXian710038China

This paper experimentally studies the cavitating fluid-structure interaction of composite hydrofoils with different ply angles.The synchronous measurement system with high-speed camera and for laser Doppler vibrometer(LDV),the feedback pressure regulation system,and the flow rate control system are established.The experimental results of the cavitation evolution show that,compared with the rigid hydrofoil,the composite hydrofoils with+45°ply angle and 0°ply angle accelerate the cavitation inception,and the composite hydrofoil with−45°ply angle delays the cavitation inception.At the same cavitation number,the cloud cavitation of the+45°laminated hydrofoil is the most severe,followed by that of the 0°laminated hydrofoil,and that of the−45°laminated hydrofoil is relatively weak and close to that of the rigid hydrofoil.The analyses of the structural vibration of the composite hydrofoils in different cavitation stages show that the three composite hydrofoils have no significant vibration at the incipient cavitation and the supercavitation,but relatively significant vibration is observed in the sheet and cloud cavitation.The vibration amplitude of the composite hydrofoil with+45°ply angle is the largest,followed by those of the−45°,0°laminated hydrofoils.In the sheet cavitation,the dominant frequencies of the structural vibration velocity of the+45°laminated hydrofoil and the−45°laminated hydrofoil are the first and second modal frequencies,but no explicit dominant frequency is observed for the 0°laminated hydrofoil.In the cloud cavitation,the dominant frequencies of the three composite hydrofoils mainly include the first modal frequency,the second modal frequency,and the cavity shedding frequency.

关键词： Cavitation fluid-structure interaction composite hydrofoil cavity induced vibration

A Hybrid Unsupervised Clustering-Based Anomaly Detection Method

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Tsinghua Science and Technology 2021年第2期26卷 146-153页

作者： guo pu Lijuan Wang Jun Shen Fang Dong School of Cyber Engineering Xidian UniversityXi'an 710126China School of Computing and Information Technology University of WollongongNSW 2522Australia School of Computer Science and Engineering Southeast UniversityNanjing 211189China

In recent years,machine learning-based cyber intrusion detection methods have gained increasing popularity.The number and complexity of new attacks continue to rise;therefore,effective and intelligent solutions are necessary.Unsupervised machine learning techniques are particularly appealing to intrusion detection systems since they can detect known and unknown types of attacks as well as zero-day attacks.In the current paper,we present an unsupervised anomaly detection method,which combines Sub-Space Clustering(SSC)and One Class Support Vector Machine(OCSVM)to detect attacks without any prior knowledge.The proposed approach is evaluated using the well-known NSL-KDD dataset.The experimental results demonstrate that our method performs better than some of the existing techniques.

关键词： unsupervised learning clustering intrusion detection feature selection

Combined Molecular Dynamics Simulation and Rouse Model Analysis of Static and Dynamic Properties of Unentangled Polymer Melts with Different Chain Architectures

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Chinese Journal of Polymer Science 2021年第4期39卷 512-524,I0008页

作者： pu Yao Lu-Kun Feng Hong-Xia guo Beijing National Laboratory for Molecular Sciences Joint Laboratory of Polymer Sciences and MaterialsState Key Laboratory of Polymer Physics and ChemistryInstitute of ChemistryChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

Chain architecture effect on static and dynamic properties of unentangled polymers is explored by molecular dynamics simulation and Rouse mode analysis based on graph theory.For open chains,although they generally obey ideal scaling in chain dimensions,local structure exhibits nonideal behavior due to the incomplete excluded volume(EV)screening,the reduced mean square internal distance(MSID)can be well described by Wittmer'theory for linear chains and the resulting chain swelling is architecture dependent,i.e.,the more branches a bit stronger swelling.For rings,unlike open chains they are compact in term of global sizes.Due to EV effect and nonconcatenated constraints their local structure exhibits a quite different non-Gaussian behavior from open chains,i.e.,reduced MSID curves do not collapse to a single master curve and fail to converge to a chain-length-independent constant,which makes the direct application of Wittmer's theory to rings quite questionable.Deviation from ideality is further evidenced by limited applicability of Rouse prediction to mode amplitude and relaxation time at high modes as well as the non-constant and mode-dependent scaled Rouse mode amplitudes,while the latter is architecture-dependent and even molecular weight dependent for rings.The chain relaxation time is architecture-dependent,but the same scaling dependence on chain dimensions does hold for all studied architectures.Despite mode orthogonality at static state,the role of cross-correlation in orientation relaxation increases with time and the time-dependent coupling parameter rises faster for rings than open chains even at short time scales it is lower for rings.

关键词： Rouse model Unentangled chains Architecture Excluded volume effects

Thulium-doped all-PM fiber chirped pulse amplifier delivering 314 W average power

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High Power Laser Science and Engineering 2023年第6期11卷 77-82页

作者： Bo Ren Can Li Tao Wang Kun guo Jian Wu pu Zhou College of Advanced Interdisciplinary Studies National University of Defense TechnologyChangshaChina Nanhu Laser Laboratory National University of Defense TechnologyChangshaChina Hunan Provincial Key Laboratory of High Energy Laser Technology National University of Defense TechnologyChangshaChina

A high-power all polarization-maintaining(PM) chirped pulse amplification(CPA) system operating in the 2.0 μm range is experimentally demonstrated.Large mode area(LMA) thulium-doped fiber(TDF) with a core/cladding diameter of25/400 μm is employed to construct the main amplifier.Through dedicated coiling and cooling of the LMA-TDF to manage the loss of the higher order mode and thermal effect,a maximum average power of 314 W with a slope efficiency of 52% and polarization extinction ratio of 20 dB is realized.The pulse duration is compressed to 283 fs with a grating pair,corresponding to a calculated peak power of 10.8 MW,considering the compression efficiency of 88% and the estimated Strehl ratio of 89%.Moreover,through characterizing the noise properties of the laser,an integrated relative intensity noise of 0.11% at 100 Hz-1 MHz is obtained at the maximum output power,whereas the laser timing jitter is degraded by the final amplifier from 318 to 410 fs at an integration frequency of 5 kHz to 1 MHz,owing to the self-phase modulation effect-induced spectrum broadening.The root-mean-square of long-term power fluctuation is tested to be0.6%,verifying the good stability of the laser operation.To the best of our knowledge,this is the highest average power of an ultrafast laser realized from an all-PM-fiber TDF-CPA system ever reported.

关键词： chirped pulse amplification high average power thulium-doped fiber laser ultrafast laser

Platinum Atoms Dispersed in Single-chain Polymer Nanoparticles

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Chinese Journal of Polymer Science 2021年第4期39卷 441-446,I0005页

作者： Zhi-Yu Hu Hong-Ting pu Jian-guo Wu Department of Polymeric Materials School of Materials Science&EngineeringTongji UniversityShanghai 201804China Key Laboratory of Advanced Civil Engineering Materials School of Materials Science&EngineeringTongji UniversityShanghai 201804China

The intramolecular cross-linking of single polymer chains can form single-chain nanoparticles(SCNPs),which have many applications.In this study,styrenic copolymers with pendent triphenylphosphine as the coordination site for platinum ions(Pt(Ⅱ))and benzocyclobutene as the latent reactive groups are synthesized.Triphenylphosphine groups in the chains can coordinate Pt(Ⅱ)and aid slight single-chain folding in dilute solution.The intramolecular cross-linking caused by the ring-open reaction of benzocyclobutene completes the single-chain collapse and forms stable SCNPs in dilute solution.Pt(Ⅱ)embedded in SCNPs can be further reduced to platinum atoms(Pt(0)).Pt(0)steadily and atomically dispersed in SCNPs exhibits better catalytic properties than normal polymer carried platinum particles do for the reduction of p-nitrophenol to p-aminophenol.

关键词： Single-chain Polymer nanoparticles Intramolecular cross-linking Platinum Coordination