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Wearable Leg Movement Monitoring System for High-precision Real-Time Metabolic Energy Estimation and Motion Recognition

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Research 2024年第2期2023卷 417-429页

作者： Jinfeng Yuan Yuzhong Zhang Shiqiang Liu Rong Zhu state key laboratory of precision measurement technology and Instruments Department of Precision InstrumentTsinghua UniversityBeijing 100084China

Comprehensive and quantitative assessment of human physical activity in daily life is valuable for healthcare,especially for those who suffer from obesity and neurological disorders or are at high risk of *** wearable devices,e.g.,smartwatches,are insufficient and inaccurate for monitoring highly dynamic limb movements and assessing human ***,we report a new wearable leg movement monitoring system incorporating a custom-made motion sensor with machine learning algorithm to perceive human motion accurately and comprehensively during diverse walking and running *** system enables real-time multimodal perceptions of personal identity,motion state,locomotion speed,and energy expenditure for wearers.A general law of extracting real-time metabolic energy from leg movements is verified although individual gaits show *** addition,we propose a novel sensing configuration combining unilateral lower leg movement velocity with its angular rate to achieve high accuracy and good generalizability while simplifying the wearable *** performances in personal identification(accuracy of 98.7%)and motion-state recognition(accuracy of 93.7%)are *** wearable system also exhibites high-precision real-time estimations of locomotion speed(error of 3.04%to 9.68%)and metabolic energy(error of 4.18%to 14.71%)for new subjects across various time-varying *** wearable system allows reliable leg movement monitoring and quantitative assessment of bodily kinematic and kinetic behaviors during daily activities,as well as safe identity authentication by gait parameters,which would greatly facilitate smart life,personal healthcare,and rehabilitation training.

关键词： smart enable monitoring

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Electrostatic generator enhancements for powering IoT nodes via efficient energy management

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Microsystems & Nanoengineering 2024年第2期10卷 143-152页

作者： Zibo Wu Zeyuan Cao Junchi Teng Rong Ding Jiani Xu Xiongying Ye state key laboratory of precision measurement technology and Instruments Department of Precision InstrumentTsinghua University100084BeijingChina

Electrostatic generators show great potential for powering widely distributed electronic devices in Internet of Things(IoT)***,a critical issue limiting such generators is their high impedance mismatch when coupled to electronics,which results in very low energy utilization ***,we present a high-performance energy management unit(EMU)based on a spark-switch tube and a buck converter with an RF *** optimizing the elements and parameters of the EMU,a maximum direct current output power of 79.2 mW m^(-2)rps^(-1)was reached for a rotary electret generator with the EMU,achieving 1.2 times greater power output than without the ***,the maximum power of the contact-separated triboelectric nanogenerator with an EMU is 1.5 times that without the *** excellent performance is attributed to the various optimizations,including utilizing an ultralow-loss spark-switch tube with a proper breakdown voltage,adding a matched input capacitor to enhance available charge,and incorporating an RF inductor to facilitate the high-speed energy transfer *** on this extremely efficient EMU,a compact self-powered wireless temperature sensor node was demonstrated to acquire and transmit data every 3.5 s under a slight wind speed of 0.5 m/*** work greatly promotes the utilization of electrostatic nanogenerators in practical applications,particularly in IoT nodes.

关键词： IoT power generator

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Metasurface array for single-shot spectroscopic ellipsometry

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Light(Science & Applications) 2024年第5期13卷 835-842页

作者： Shun Wen Xinyuan Xue Shuai Wang Yibo Ni Liqun Sun Yuanmu Yang Department of precision Instrument State Key Laboratory of Precision Measurement Technology and InstrumentsTsinghua UniversityBeijing 100084China

Spectroscopic ellipsometry is a potent method that is widely adopted for the measurement of thin film thickness and refractive *** conventional ellipsometers utilize mechanically rotating polarizers and grating-based spectrometers for spectropolarimetric ***,we demonstrated a compact metasurface array-based spectroscopic ellipsometry system that allows single-shot spectropolarimetric detection and accurate determination of thin film properties without any mechanical *** silicon-based metasurface array with a highly anisotropic and diverse spectral response is combined with iterative optimization to reconstruct the full Stokes polarization spectrum of the light reflected by the thin film with high ***,the film thickness and refractive index can be determined by fitting the measurement results to a proper material model with high *** approach opens up a new pathway towards a compact and robust spectroscopic ellipsometry system for the high throughput measurement of thin film properties.

关键词： properties. spectroscopic film

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Frequency-modulated continuous-wave multiplexed gas sensingbased on optical frequency comb calibration

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Chinese Physics B 2024年第9期33卷 152-163页

作者： Linhua Jia Xinghua Qu Fumin Zhang state key laboratory of precision measurement technology and Instruments Tianjin UniversityTianjin 300072China

Laser absorption spectroscopy has proven to be an effective approach for gas sensing, which plays an important rolein the fields of military, industry, medicine and basic research. This paper presents a multiplexed gas sensing system basedon optical frequency comb (OFC) calibrated frequency-modulated continuous-wave (FMCW) tuning nonlinearity. Thesystem can be used for multi-parameter synchronous measurement of gas absorption spectrum and multiplexed opticalpath. Multi-channel parallel detection is realized by combining wavelength division multiplexing (WDM) and frequencydivision multiplexing (FDM) techniques. By introducing nonlinear optical crystals, broadband spectrum detection is simultaneouslyachieved over a bandwidth of hundreds of nanometers. An OFC with ultra-high frequency stability is used asthe frequency calibration source, which guarantees the measurement accuracy. The test samples involve H13C14N, C_(2)H_(2)and Rb vapor cells of varying densities and 5 parallel measurement experiments are designed. The results show that themeasurement accuracies of spectral absorption line and the optical path are 150 MHz and 20 m, respectively. The schemeoffers the advantages of multiplexed, multi-parameter, wide spectrum and high resolution detection, which can realize theidentification of multi-gas components and the high-precision inversion of absorption lines under different *** proposed sensor demonstrates great potential in the field of high-resolution absorption spectrum measurement for gassensing applications.

关键词： frequency-modulated continuous-wave (FMCW) technology optical frequency comb multiplexing absorption spectroscopy

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Voltage-modulated polymer nanopore field-effect transistor for multi-sized nanoparticle detection

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Nanotechnology and precision Engineering 2024年第3期7卷 79-89页

作者： Feng Zhou Lin Li Qiannan Xue state key laboratory of precision measurement technology and Instruments School of Precision Instruments and Optoelectronics EngineeringTianjin UniversityTianjin 300072China

Solid-state nanopores offer a range of distinct advantages over biological nanopores,such as structural diversity and greater stability and durability;this makes them highly promising for high-resolution nanoparticle *** nanopores can exhibit gating characteristics with stress-responsive switches and can demonstrate specificity toward particular *** inspiration from biological nanopores,this paper introduces a novel polymer nanopore with field-effect characteristics,leveraging a conductive polymer in its construction to showcase intriguing gating ***,in this device,the polymer layer serves as the gate,enabling precise control over the source–drain current response inside and outside the pore by simply adjusting the gate *** unique feature allows fine-tuning of the nanopore’s sensitivity to nanoparticles of varying sizes and facilitates its operation in multiple *** results reveal that the developed polymer nanopore field-effect transistor demonstrates remarkable selectivity in detecting nanoparticles of various sizes under different applied *** proposed single device demonstrates the exceptional ability to detect multiple types of nanoparticle,showcasing its immense potential for a wide range of applications in biological-particle analysis and medical diagnostics.

关键词： Nanopipette Polymer nanopore Voltage modulation Nanoparticle detection

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A novel dual-channel thermo-optic locking method for the whispering gallery mode microresonator

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Chinese Physics B 2024年第5期33卷 438-444页

作者：范文杰刘文耀潘梓文王蓉刘来邢恩博周彦汝唐军刘俊 state key laboratory of Dynamic measurement technology North University of ChinaTaiyuan 030051China Shanxi Province key laboratory of Quantum Sensing and precision measurement North University of ChinaTaiyuan 030051China

Mode locking can be effectively achieved by using the thermo-optic effects in the whispering gallery mode(WGM)optical microcavity,without the help of external ***,it has the advantages of small size,low integration costs,and self-locking,which shows great potential for ***,the conventional single-channel microcavity thermal-locking method that relies solely on internal thermal balance will inevitably be disturbed by the external *** limitation affects the locking time and ***,in this paper,we propose a new method for closed-loop thermal locking of a dual-channel *** thermal locking of the signal laser and the thermal regulation of the control laser are carried out respectively by synchronously drawing a dual-path tapered *** theoretical model of the thermal dynamics of the dual-channel microcavity system is established,and the influence of the control-laser power on the thermal locking of the signal laser is *** deviation between the locking voltage of the signal laser and the set point value is used as a closed-loop feedback parameter to achieve long-term and highly stable mode locking of the signal *** results show that in the 2.63 h thermal-locking test,the locking stability is an order of magnitude higher than that of the single tapered *** solution addresses the issue of thermal locking being disrupted by the external environment,and offers new possibilities for important applications such as spectroscopy and micro-optical sensor devices.

关键词： optical microcavity thermo-optic locking thermal nonlinearity effect

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Ultrafast optical investigation of carrier and spin dynamics in low-dimensional perovskites

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Science China(Technological Sciences) 2024年第1期67卷 2-18页

作者： FU JinYue JIANG Ying FANG HongHua key laboratory for Micro-Nano Physics and technology of Hunan Province School of Physics and ElectronicsHunan UniversityChangsha 410012China state key laboratory of precision measurement technology and Instruments Department of Precision InstrumentTsinghua UniversityBeijing 100084China

Low-dimensional perovskite(PVK)materials have attracted significant research interest,because of their quantum-confined effect,tunable band gap structures,and higher stability than that of three-dimensional(3D)*** semiconductor optoelectronic devices,high speed and small size are closely *** development of high-speed devices requires researchers to fully understand the properties of materials,especially the dynamic processes such as carrier recombination,separation,and transport,which often play a crucial role in the performance of *** an indispensable part of dynamic research,spin relaxation is also of great significance in studying the properties of materials and explore possible *** halide PVK materials have strong spin-orbit coupling(SOC),which provides a basis for information storage and processing by using spin degrees of ***,studying the carrier and spin dynamics of low-dimensional PVKs is an effective way to understand the internal properties of low-dimensional PVKs *** paper summarizes the latest research progress on the ultrafast carrier and spin dynamics in low-dimensional PVKs,to comprehensively understand their carrier and spin behaviors and present an outlook for relevant studies in this area.

关键词： low-dimensional perovskites carrier dynamics spin dynamics optoelectronic devices

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Laser manufacturing of spatial resolution approaching quantum limit

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Light(Science & Applications) 2024年第3期13卷 421-428页

作者： Xiao-Jie Wang Hong-Hua Fang Zhen-Ze Li Dan Wang Hong-Bo Sun state key laboratory of precision measurement technology and Instruments Department of Precision InstrumentTsinghua UniversityBeijing 100084China state key laboratory of Integrated Optoelectronics College of Electronic Science and EngineeringJilin University2699 Qianjin StreetChangchun 130012China

Atomic and close-to-atom scale manufacturing is a promising avenue toward single-photon emitters,single-electron transistors,single-atom memory,and quantum-bit devices for future communication,computation,and sensing *** manufacturing is outstanding to this end for ease of beam manipulation,batch production,and no requirement for *** is,however,suffering from optical diffraction ***,we report a spatial resolution improved to the quantum limit by exploiting a threshold tracing and lock-in method,whereby the two-order gap between atomic point defect complexes and optical diffraction limit is surpassed,and a feature size of<5 nm is *** underlying physics is that the uncertainty of local atom thermal motion dominates electron excitation,rather than the power density slope of the incident *** show that the colour centre yield in hexagonal boron nitride is transformed from stochastic to deterministic,and the emission from individual sites becomes polychromatic to *** a result,single colour centres in the regular array are deterministically created with a unity yield and high positional accuracy,serving as a step forward for integrated quantum technological applications.

关键词： quantum limit resolution

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Spatial light modulation for femtosecond laser manufacturing:Current developments and challenges

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Science China(Technological Sciences) 2024年第1期67卷 60-72页

作者： ZANG Xue LIU ZiTing XU YiShi WANG Yi WANG Qing LI ZhenZe WANG Lei state key laboratory of Integrated Optoelectronics College of Electronic Science and EngineeringJilin UniversityChangchun 130012China state key laboratory of precision measurement and Instruments Department of Precision InstrumentTsinghua UniversityBeijing 100084China

Since the invention of lasers,spatial-light-modulated laser processing has become a powerful tool for various *** enables multidimensional and dynamic modulation of the laser beam,which significantly improves the processing efficiency,accuracy,and flexibility,and presents wider prospects over traditional mechanical technologies for machining three-dimensional,hard,brittle,or transparent *** this review,we introduce:(1)The role of spatial light modulation technology in the development of femtosecond laser manufacturing;(2)the structured light generated by spatial light modulation and its generation methods;and(3)representative applications of spatial-light-modulated femtosecond laser manufacturing,including aberration correction,parallel processing,focal field engineering,and polarization ***,we summarize the present challenges in the field and possible future research.

关键词： femtosecond laser manufacturing spatial light modulation structured light aberration correction parallel processing focal field engineering polarization control

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Design of a high sensitivity and wide range angular rate sensor based on exceptional surface

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Chinese Physics B 2024年第8期33卷 277-286页

作者：丁鑫圣刘文耀王师贤陶煜周彦汝白禹刘来邢恩博唐军刘俊 state key laboratory of Dynamic measurement technology North University of ChinaTaiyuan 030051China Shanxi Province key laboratory of Quantum Sensing and precision measurement North University of ChinaTaiyuan 030051China

It is found that when the parity–time symmetry phenomenon is introduced into the resonant optical gyro system and it works near the exceptional point,the sensitivity can in theory be significantly amplified at low angular ***,in fact,the exceptional point is easily disturbed by external environmental variables,which means that it depends on harsh experimental environment and strong control ability,so it is difficult to move towards practical ***,we propose a new angular rate sensor structure based on exceptional surface,which has the advantages of high sensitivity and high *** system consists of two fiber-optic ring resonators and two optical loop mirrors,and one of the resonators contains a variable ratio coupler and a variable optical *** theoretically analyze the system response,and the effects of phase and coupling ratio on the system ***,compared with the conventional resonant gyro,the sensitivity of this exceptional surface angular rate sensor can be improved by about 300 times at low *** addition,by changing the loss coefficient in the ring resonator,we can achieve a wide range of 600 rad/*** scheme provides a new approach for the development of ultra-high sensitivity and wide range angular rate sensors in the future.

关键词： exceptional surface exceptional points ring resonator angular rate sensing rotational direction recognition wide operating range

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