Analysis of One-Dimensional Compression under a Wide Range of Stress with Densely Arrayed BPM

In this paper,the densely arrayed bonded particle model is proposed for simulation of granular materials with discrete element method(DEM)considering particle crushing.This model can solve the problem of pore calculation after the grains are crushed,and reduce the producing time of specimen.In this work,several one-dimensional compressing simulations are carried out to investigate the effect of particle crushing on mechanical properties of granular materials under a wide range of stress.The results show that the crushing process of granular materials can be divided into four different stages according to er-logσy curves.At the end of the second stage,there exists a yield point,after which the physical and mechanical properties of specimens will change significantly.Under extremely high stress,particle crushing will wipe some initial information of specimens,and specimens with different initial gradings and void ratios present some similar characteristics.Particle crushing has great influence on grading,lateral pressure coefficient and compressibility of granular materials,and introduce extra irreversible volume deformation,which is necessary to be considered in modelling of granular materials in wide stress range.

Design and fabrication of multi-channel photodetector array monolithic with arrayed waveguide grating

We have provided optical simulations of the evanescently coupled waveguide photodiodes integrated with a 13- channels AWGs. The photodiode could exhibit high internal efficiency by appropriate choice of layers geometry and refrac- tive index. Aseamless joint structure has been designed and fabricated for integrating the output waveguides of AWGs with the evanescently coupled waveguide photodiode array. The highest simulation quantum efficiency could achieve 92% when the matching layer thickfiess of the PD is 120 nm and the insertion length is 2 μm. The fabricated PD with 320-nm-thick match.ing layer and 2-μm-length insertion matching layer present a responsivity of 0.87 A/W.

A 32-channel 100 GHz wavelength division multiplexer by interleaving two silicon arrayed waveguide gratings

A 32-channel wavelength division multiplexer with 100 GHz spacing is designed and fabricated by interleaving two silicon arrayed waveguide gratings(AWGs).It has a parallel structure consisting of two silicon 16-channel AWGs with200 GHz spacing and a Mach-Zehnder interferometer(MZI)with 200 GHz free spectral range.The 16 channels of one silicon AWG are interleaved with those of the other AWG in spectrum,but with an identical spacing of 200 GHz.For the composed wavelength division multiplexer,the experiment results reveal 32 wavelength channels in C-band,a wavelength spacing of 100 GHz,and a channel crosstalk lower than-15 dB.

Improved Performance of a Wavelength-Tunable Arrayed Waveguide Grating in Silicon on Insulator

The improved performance of a wavelength-tunable arrayed waveguide grating (AWG) is demonstrated, including the crosstalk, insertion loss and the wavelength tuning efficiency. A reduced impact of the fabrication process on the AWG is achieved by the design of bi-level tapers. The wavelength tuning of the AWG is achieved according to the thermo-optic effect of silicon, and uniform heating of the silicon waveguide layer is achieved by optimizing the heater design. The fabricated AWG shows a minimum crosstalk of 16 dB, a maximum insertion loss of 3.91 dB and a wavelength tuning efficiency of 8.92 nm/W, exhibiting a ～8 dB improvement of crosstalk, ～2.1 dB improvement of insertion loss and ～5 nm/W improvement of wavelength tuning efficiency, compared to our previous reported results.

Novel wavelength-accurate InP-based arrayed waveguide grating

A 13-channel, InP-based arrayed waveguide grating （AWG） is designed and fabricated in which the on-chip loss of the central channel is about -5 dB and the crosstalk is less than -23 dB in the center of the spectrum response. However, the central wavelength and channel spacing are deviated from the design values. To improve their accuracy, an optimized design is adopted to compensate the process error. As a result, the central wavelength 1549.9 nm and channel spacing 1.59 nm are obtained in the experiment, while their design values are 1549.32 nm and 1.6 nm, respectively. The route capability and thermo-optic characteristic of the AWG are also discussed in detail.

Design and Fabrication of a 400 GHz InP-Based Arrayed Waveguide Grating with Flattened Spectral Response

A four-channel 400 GHz channel spacing InP-based arrayed waveguide grating with a flattened wavelength re- sponse by employing a multimode interference coupler at the input waveguide of the filter is prepared. The fabricated devices show a flattened spectral response with a broadened 3-dB bandwidth up to 3.5 nm, interchan- nel non-uniformity of 〈0. 7dB and excellent match to the simulation results.

Near Infrared Fluorescence Enhancement by Local Surface Plasmon Resonance from Arrayed Gold Nanoblocks

The near infrared (NIR) fluorescence enhancement by local surface plasmon resonanoce from arrayed gold (Au) nanoblocks was investigated by NIR fluorescent dyes, IR780, immobilized in hydrophobic DNA thin film on glass substrates, to clarify the gap mode effect on the fluorescence enhancement. In the substrate with Dimer type Au nanoblock arrangement, average total fluorescence intensity was larger by 10.0, 2.4, and 12.4 times for non-polarized, P- and S- polarization as compared with that on a glass substrate alone, respectively. These findings suggested that enhancement of excitation light intensity at nanogap in the Dimer type Au nanoblock arrangement affected the fluorescence intensity. Average total fluorescence intensity, on the other hand, was smaller by 0.63 times as compared with that on a glass substrate alone in the checkerboard type Au array. It is suggested that the fluorescence quenching was caused by the energy transfer from the excited state of IR780 to Au nanoblocks or by the increased deactivation of excited dye molecules induced by resonance with Au nanoblocks at the checkerboard arrangement. We have firstly achieved the NIR fluorescence enhancement by LSPR due to the gap mode.

Ultralow cross talk arrayed waveguide grating integrated with tunable microring filter array

The silicon-based arrayed waveguide grating(AWG)is widely used due to its compact footprint and its compatibility with the mature CMOS process.However,except for AWGs with ridged waveguides of a few micrometers of cross section,any small process error will cause a large phase deviation in other AWGs,resulting in an increasing cross talk.In this paper,an ultralow cross talk AWG via a tunable microring resonator(MRR)filter is demonstrated on the SOI platform.The measured insertion loss and minimum adjacent cross talk of the designed AWG are approximately 3.2 and-45.1 d B,respectively.Compared with conventional AWG,its cross talk is greatly reduced.

Arrayed piezoresistive and inertial measurement unit sensor-integrated assistant training tennis racket for multipoint hand pressure monitoring and representative action recognition

Technology-assisted ball training systems have become a research hotspot due to their ability to provide quantitative data for guiding athletes to address their areas of improvement.However,traditional tennis training systems still have some limitations;for instance,they are subjective,expensive,heavy,and time-consuming.In this research,an assistant training tennis racket,which consists of arrayed flexible sensors and an inertial measurement unit,has been proposed to comprehensively analyze the representative actions’force and acceleration.Consisting of MXene as the sensitive material and melamine sponge as the substrate(named MMSS),the flexible sensor exhibited an excellent sensitivity of 5.35 kPa^(-1)(1.1-22.2 kPa)due to the formation of a 3D conductive network.Moreover,the sensor retained a high sensitivity of 0.6 k Pa-1in an ultrawide measurement range(22.2-266 kPa).In addition to recognizing the type of hitting action,an artificial intelligence algorithm was introduced to accurately differentiate the five typical motion behaviors with an accuracy rate of 98.2%.This study not only proposes a comprehensive assistant training tennis racket for improving the techniques of tennis enthusiasts but also a new information processing scheme for intelligent sensing and distinction of different movements,which can offer significant application potential in sports big data collection and the Internet of things.

核型分析联合其他遗传学检测技术在高龄孕妇产前诊断中的应用

目的探讨核型分析联合单核苷酸多态性微阵列技术(single nucleotide polymorphism array,SNP array)或荧光原位杂交技术(fluorescence in situ hybridization,FISH)或细菌人工染色体微珠标记技术(BACs on Beads,BoBs)在高龄孕妇产前诊断中的应用价值。方法回顾性研究因高龄行产前诊断的930例孕妇,全部行核型分析,联合BoBs检测420例,联合SNP array检测343例,联合FISH检测167例,分析其染色体结果及妊娠结局。结果930例胎儿中,核型异常192例(20.7%),三体综合征中以21-三体居多,性染色体异常中以克氏征居多。在核型联合其他检测中,联合SNP array检测可显著提高胎儿染色体异常检出率,差异有统计学意义(χ^(2)=6.191,P=0.013)。对于染色体嵌合体的诊断,核型联合FISH检测可更精准地确定嵌合类型及比例。孤立性高龄胎儿染色体异常风险相对较低,高龄合并无创高危胎儿染色体异常率最高,在高龄合并超声软指标中,随超声软指标数目增多,染色体异常率随之升高(P=0.001)。高龄孕妇年龄与核型异常、非整倍体尤其21三体的发生率呈正相关(P<0.05)。结论孤立性高龄孕妇胎儿染色体异常风险相对较低,高龄合并无创高危胎儿染色体异常的风险高,随超声软指标数目增多、孕妇年龄增长胎儿染色体异常的风险增加,核型联合FISH检测可更精准地确定嵌合类型及比例,核型分析联合其他检测尤其与SNP array技术可显著提高染色体异常检出率,有利于遗传咨询及再生育指导,是高龄孕妇首选的产前诊断方案。

Toward optical coherence tomography on a chip: in vivo three-dimensional human retinal imaging using photonic integrated circuit-based arrayed waveguide gratings

In this work,we present a significant step toward in vivo ophthalmic optical coherence tomography and angiography on a photonic integrated chip.The diffraction gratings used in spectral-domain optical coherence tomography can be replaced by photonic integrated circuits comprising an arrayed waveguide grating.Two arrayed waveguide grating designs with 256 channels were tested,which enabled the first chip-based optical coherence tomography and angiography in vivo three-dimensional human retinal measurements.Design 1 supports a bandwidth of 22nm,with which a sensitivity of up to 91 dB(830μW) and an axial resolution of 10.7 pm was measured.Design 2 supports a bandwidth of 48 nm,with which a sensitivity of 90 dB(480μW) and an axial resolution of 6.5μm was measured.The silicon nitride-based integrated optical waveguides were fabricated with a fully CMOS-compatible process,which allows their monolithic co-integration on top of an optoelectronic silicon chip.As a benchmark for chip-based optical coherence tomography,tomograms generated by a commercially available clinical spectral-domain optical coherence tomography system were compared to those acquired with on-chip gratings.The similarities in the tomograms demonstrate the significant clinical potential for further integration of optical coherence tomography on a chip system.

Integrated scanning spectrometer with a tunable micro-ring resonator and an arrayed waveguide grating

Integrated spectrometers with both wide optical bandwidths and high spectral resolutions are required in applications such as spectral domain optical coherence tomography(SD-OCT).Here we propose a compact integrated scanning spectrometer by using a tunable micro-ring resonator(MRR)integrated with a single arrayed waveguide grating for operation in the 1265-1335-nm range.The spectral resolution of the spectrometer is determined by the quality factor of the MRR,and the optical bandwidth is defined by the free spectral range of the arrayed waveguide grating.The spectrometer is integrated with on-chip germanium photodetectors,which enable direct electrical readout.A 70-nm optical bandwidth and a 0.2-nm channel spacing enabled by scanning the MRR across one free spectral range are demonstrated,which offer a total of350 wavelength channels with 31-kHz wavelength scanning speed.The integrated spectrometer is applied to measure different spectra and the interference signals from an SD-OCT system,which shows its great potential for future applications in sensing and imaging systems.

Design and Fabrication of Polymer Arrayed Waveguide Grating

In this paper, based on the principle of Arrayed Waveguide Grating (AWG)theory, some important parameters are optimized for polymer AWG around the central wavelength of1.55μm with the wavelength spacing of 1.6 nm. Then, a 9 X 9 polymer AWG is designed and thefabricating process are described . The cladding material is poly-methyl-methacrylate-co-glyciclylmethacrylate (PMMA-GMA) and the core material is the mixture of PMMA-GMA and bis-phonel-A epoxy. Inorder to obtain a better shape of the waveguide after the Reactive Ion Etching (RIE) using oxygen,an aluminum mask is used on polymer instead of conventional photoresist as mask in the fabricationprocess. The measuring results indicate that the fabricated optical waveguide achieves single-modetransmission.

Characterization of Birefringence and Dispersion Properties in an Arrayed Waveguide Grating

We have characterized polarization dependent loss(PDL), differential group delay(DGD), and chromatic dispersion of an AWG and a simple method was proposed to estimate the chromatic dispersion from the measured DGD of the device.

Analysis of fabrication results for 17×17 polymer arrayed waveguide grating multiplexers with flat spectral responses

Based on transmission theory, a 17 x 17 polymer arrayed waveguide grating （AWG） multiplexer para meter optimization is performed, and the influence of the fabrication results on the transmission characteristics are analyzed. In this paper, we mainly discuss three of the main errors in the fabrication of polymer AWG devices. One is 3n 1, which is caused by the tuning of the core refractive index n 1, the second is 8b, which results from the rotating-coating of the core thickness b, and the other is the non-ideal core cross-section, which is caused by steam redissolution. The effects of the above fabrication errors on the transmission characteristics of the AWG device are investigated, and compensation techniques are proposed. By comparing the theoretical simulation and experimental results, the shift in the transmission spectrum is reduced by 0.028 nm, the 3 dB bandwidth is increased by about 0.036 nm, the insertion loss is reduced by about 3 dB for the central channel and 4.5 dB for the edge channels, and the crosstalk is reduced by 1.5 dB.

16 channel 200 GHz arrayed waveguide grating based on Si nanowire waveguides

A 16 channel arrayed waveguide grating demultiplexer with 200 GHz channel spacing based on Si nanowire waveguides is designed. The transmission spectra response simulated by transmission function method shows that the device has channel spacing of 1.6 nm and crosstalk of 31 dB. The device is fabricated by 193 nm deep UV lithography in silicon-on-substrate. The demultiplexing characteristics are observed with crosstalk of 5-8 dB, central channel＇s insertion loss of 2.2 dB, flee spectral range of 24.7 nm and average channel spacing of 1.475 nm. The cause of the spectral distortion is analyzed specifically.

Detection of dynamic strain using an SOA-fiber ring laser and an arrayed waveguide grating demodulator

In this letter,a fiber Bragg grating(FBG)dynamic strain sensing system using a semiconductor optical amplifier(SOA)-fiber ring laser(FRL)and an arrayed waveguide grating(AWG)demodulator is proposed.Due to the characteristics of SOA,it can act as the gain medium as well as light source.The AWG module is used as the wavelength demodulator.It is shown that SOA-based FRL sensors can accurately respond to 1.5μεdynamic strain signal with high frequency up to 120 k Hz and almost no distortion in the waveforms.Experimental results show that the system can be used for acoustic testing,such as underwater ultrasonic detection and external impact monitoring.In addition,the simultaneous dual-channel demodulated system is investigated in detail to verify the multiplexing.This dynamic strain sensing system can be widely utilized in structural health monitoring because of its high stability,low cost and good multiplexability.

Low-Complexity Reconstruction of Covariance Matrix in Hybrid Uniform Circular Array

Spatial covariance matrix(SCM) is essential in many multi-antenna systems such as massive multiple-input multiple-output(MIMO). For multi-antenna systems operating at millimeter-wave bands, hybrid analog-digital structure has been widely adopted to reduce the cost of radio frequency chains.In this situation, signals received at the antennas are unavailable to the digital receiver, and as a consequence, traditional sample average approach cannot be used for SCM reconstruction in hybrid multi-antenna systems. To address this issue, beam sweeping algorithm(BSA) which can reconstruct the SCM effectively for a hybrid uniform linear array, has been proposed in our previous works. However, direct extension of BSA to a hybrid uniform circular array(UCA)will result in a huge computational burden. To this end, a low-complexity approach is proposed in this paper. By exploiting the symmetry features of SCM for the UCA, the number of unknowns can be reduced significantly and thus the complexity of reconstruction can be saved accordingly. Furthermore, an insightful analysis is also presented in this paper, showing that the reduction of the number of unknowns can also improve the accuracy of the reconstructed SCM. Simulation results are also shown to demonstrate the proposed approach.

Recent Advances in In-Memory Computing:Exploring Memristor and Memtransistor Arrays with 2D Materials

The conventional computing architecture faces substantial chal-lenges,including high latency and energy consumption between memory and processing units.In response,in-memory computing has emerged as a promising alternative architecture,enabling computing operations within memory arrays to overcome these limitations.Memristive devices have gained significant attention as key components for in-memory computing due to their high-density arrays,rapid response times,and ability to emulate biological synapses.Among these devices,two-dimensional(2D)material-based memristor and memtransistor arrays have emerged as particularly promising candidates for next-generation in-memory computing,thanks to their exceptional performance driven by the unique properties of 2D materials,such as layered structures,mechanical flexibility,and the capability to form heterojunctions.This review delves into the state-of-the-art research on 2D material-based memristive arrays,encompassing critical aspects such as material selection,device perfor-mance metrics,array structures,and potential applications.Furthermore,it provides a comprehensive overview of the current challenges and limitations associated with these arrays,along with potential solutions.The primary objective of this review is to serve as a significant milestone in realizing next-generation in-memory computing utilizing 2D materials and bridge the gap from single-device characterization to array-level and system-level implementations of neuromorphic computing,leveraging the potential of 2D material-based memristive devices.

Simulation and fabrication of in vitro microfluidic microelectrode array chip for patterned culture and electrophysiological detection of neurons

To enable the detection and modulation of modularized neural networks in vitro,this study proposes a microfluidic microelectrode array chip for the cultivation,compartmentalization,and control of neural cells.The chip was designed based on the specific structure of neurons and the requirements for detection and modulation.Finite-element analysis of the chip’s flow field was conducted using the COMSOL Multiphysics software,and the simulation results show that the liquid within the chip can flow smoothly,ensuring stable flow fields that facilitate the uniform growth of neurons within the microfluidic channels.By employing MEMS technology in combination with nanomaterial modification techniques,the microfluidic microelectrode array chip was fabricated successfully.Primary hippocampal neurons were cultured on the chip,forming a well-defined neural network.Spontaneous electrical activity of the detected neurons was recorded,exhibiting a 23.7%increase in amplitude compared to neuronal discharges detected on an open-field microelectrode array.This study provides a platform for the precise detection and modulation of patterned neuronal growth in vitro,potentially serving as a novel tool in neuroscience research.