- 标题
- 摘要
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- 实验方案
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Scanning Surface Plasmon Microscope for Sensing Lipid Array and Au Film Defect
摘要： We demonstrated a scanning radially-polarized surface plasmon microscopy (SSPM) with submicron lateral resolution and high refractive index sensitivity. According to the captured images, SSPM could be used to verify the quality of deposited Au film and Au structure on surface plasmon sensing chip. The defect on the SPR chip, which disturbed the plasmonic wave around the focal point, could be easily detected by our system. Moreover, the application of SSPM in imaging lipid array was showed in this article. The 1, 2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC) array was made by dip-pen nanolithography. The results indicated that SSPM system could be used in comparing the thickness of DOPC array. Because of the high sensitivity and high spatial resolution of the system, we expected the SSPM to be used in measuring the properties of nanogold array structures and apply to digital-array biosensors in nanoscale.
关键词： 1,2-Dioleoyl-sn-glycero-3-phosphocholine,Scanning surface plasmon microscope,lipid array,nanostructure
更新于2025-09-23 15:22:29
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Fabrication and characterization of VOC sensor array based on SnO2 and ZnO nanoparticles functionalized by metalloporphyrins
摘要： A volatile organic compound (VOC) sensor array based on metal oxide nanoparticles (MOX NPs) functionalized by metalloporphyrins (MPPs) was demonstrated. The VOC sensor array was composed of four single sensors based on SnO2 NPs/cobalt-porphyrin, SnO2 NPs/zinc-porphyrin, SnO2 NPs/nickel-porphyrin and ZnO NPs/cobalt-porphyrin. The MOX NP/MPP-based sensors were fabricated by drop-casting the MOX NPs dispersion and MPPs solution onto a MEMS platform. The fabricated sensor successfully detected toluene at a concentration as low as 20 ppb, which is below the limit detection concentration of previously reported porphyrin-based VOC sensor arrays. We also confirmed the selectivity between benzene, toluene, ethylbenzene, and xylene (BTEX) by using principal component analysis in contrast to previous studies on MOX/MPP-based sensor. BTEX was classified from 1 to 9 ppm at a resolution of 2 ppm, and the sensor array showed stable performance even after considerable impact.
关键词： Gas sensor array,Porphyrin,Principle component analysis,Metal oxide,Volatile organic compound
更新于2025-09-23 15:22:29
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A true-time-delay transmit/receive module for X-band subarray phased arrays
摘要： This letter presents the implementation of a 6-bit true-time-delay (TTD) transmit/receive (T/R) module in X-band. Improved phase linearity is achieved by using thin film coplanar waveguide transmission lines than traditional microstrip lines or lumped LC components of the most other TTD designs. In order to meet the requirement of the large dynamic temperature range in practice, the hybrid coupler reflective phase shifters with varactor diodes are adopted in long-time-delay units as temperature compensations for thermal phase drift. Experimental results of this TTD T/R module are carried out within a bandwidth of 1.2 GHz at X-band. The gain flatness is better than 1 dB and RMSE of the phase errors is less than 7° in all the transmitting and receiving delay states.
关键词： true time delay (TTD),receive module,phased array,coplanar waveguide,phase shifter
更新于2025-09-23 15:22:29
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Perpendicular-Corporate Feed in a Four-Layer Circularly-Polarized Parallel-Plate Slot Array
摘要： This paper presents a design for the perpendicular-corporate feed in a four-layer circularly-polarized parallel-plate slot array antenna. We place a dielectric layer with adequate permittivity in the region between the coupling-aperture and the radiating-slot layers to remove x-shaped cavity walls completely in the radiating part of a conventional planar corporate-feed waveguide slot array antenna. To address fabrication constraints, the dielectric layer consists of PTFE and air. It excites a strong standing wave in the region and so provides 2 × 2-element subarrays with uniform excitation. None of the slot layers are in electrical contact due to air gaps between the slot layers. The four-layer structure with apertures for circular polarization contributes to wideband design for axial ratios because of the eigenmodes in the desired band. We realize an 11.9% bandwidth for axial ratios of less than 3.0 dB as confirmed by measurements in the 60 GHz band. At the design frequency, the measured realized gain is 32.7 dBi with an antenna efficiency of 75.5%.
关键词： slot array,perpendicular-corporate feed,circularly-polarization,parallel plates
更新于2025-09-23 15:22:29
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Secure Point-to-Multipoint Communication Using the Spread Spectrum Assisted Orthogonal Frequency Diverse Array in Free Space
摘要： Wireless communication security has been increasingly important nowadays. Directional modulation (DM) is seen as a promising wireless physical layer security technology. Traditional DM is a transmit-side technology that projects digitally modulated information signals in the desired directions (or at the desired locations) while simultaneously distorting the constellation formats of the same signals in other directions (or at all other locations). However, these directly exposed digitally modulated information signals are easily intercepted by eavesdroppers along the desired directions (or around the desired locations). A new DM scheme for secure point-to-multipoint communication based on the spread spectrum assisted orthogonal frequency diverse array (short for SS-OFDA-M-DM) is proposed in this paper. It can achieve point-to-multipoint secure communication for multiple cooperative receivers at different locations. In the proposed SS-OFDA-M-DM scheme, only cooperative users that use specific DM receivers with right spread spectrum parameters can retrieve right symbols. Eavesdroppers without knowledge of spread spectrum parameters cannot intercept useful signals directly at the desired locations. Moreover, they cannot receive normal symbols at other locations either even if the right spread spectrum parameters are known. Numerical simulation results verify the validity of our proposed scheme.
关键词： Frequency diverse array,Spread spectrum,Directional modulation,Secure point-to-multipoint communication
更新于2025-09-23 15:22:29
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Amplitude Modulation-based Electrical Stimulation for Encoding Multipixel Spatiotemporal Visual Information in Retinal Neural Activities
摘要： Retinal implants have been developed as a promising way to restore partial vision for the blind. The observation and analysis of neural activities can offer valuable insights for successful prosthetic electrical stimulation. Retinal ganglion cell (RGC) activities have been investigated to provide knowledge on the requirements for electrical stimulation, such as threshold current and the effect of stimulation waveforms. To develop a detailed 'stimulation strategy' for faithful delivery of spatiotemporal visual information to the brain, it is essential to examine both the temporal and spatial characteristics of RGC responses, whereas previous studies were mainly focused on one or the other. In this study, we investigate whether the spatiotemporal visual information can be decoded from the RGC network activity evoked by patterned electrical stimulation. Along with a thorough characterization of spatial spreading of stimulation current and temporal information encoding, we demonstrated that multipixel spatiotemporal visual information can be accurately decoded from the population activities of RGCs stimulated by amplitude-modulated pulse trains. We also found that the details of stimulation, such as pulse amplitude range and pulse rate, were crucial for accurate decoding. Overall, the results suggest that useful visual function may be restored by amplitude modulation-based retinal stimulation.
关键词： Degenerated Retina,Electrical Stimulation,Retinal Ganglion Cells,Retinal Implant,Spike Train Decoding,Microelectrode Array
更新于2025-09-23 15:22:29
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Non-parametric Physiological Classification of Retinal Ganglion Cells in the Mouse Retina
摘要： Retinal ganglion cells, the sole output neurons of the retina, exhibit surprising diversity. A recent study reported over 30 distinct types in the mouse retina, indicating that the processing of visual information is highly parallelised in the brain. The advent of high density multi-electrode arrays now enables recording from many hundreds to thousands of neurons from a single retina. Here we describe a method for the automatic classification of large-scale retinal recordings using a simple stimulus paradigm and a spike train distance measure as a clustering metric. We evaluate our approach using synthetic spike trains, and demonstrate that major known cell types are identified in high-density recording sessions from the mouse retina with around 1,000 retinal ganglion cells. A comparison across different retinas reveals substantial variability between preparations, suggesting pooling data across retinas should be approached with caution. As a parameter-free method, our approach is broadly applicable for cellular physiological classification in all sensory modalities.
关键词： classification,retinal ganglion cells,light responses,spike distance,multi-electrode array
更新于2025-09-23 15:22:29
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A Versatile Silicon-Silicon Nitride Photonics Platform for Enhanced Functionalities and Applications
摘要： Silicon photonics is one of the most prominent technology platforms for integrated photonics and can support a wide variety of applications. As we move towards a mature industrial core technology, we present the integration of silicon nitride (SiN) material to extend the capabilities of our silicon photonics platform. Depending on the application being targeted, we have developed several integration strategies for the incorporation of SiN. We present these processes, as well as key components for dedicated applications. In particular, we present the use of SiN for athermal multiplexing in optical transceivers for datacom applications, the nonlinear generation of frequency combs in SiN micro-resonators for ultra-high data rate transmission, spectroscopy or metrology applications and the use of SiN to realize optical phased arrays in the 800–1000 nm wavelength range for Light Detection And Ranging (LIDAR) applications. These functionalities are demonstrated using a 200 mm complementary metal-oxide-semiconductor (CMOS)-compatible pilot line, showing the versatility and scalability of the Si-SiN platform.
关键词： transceiver,silicon photonics,Kerr nonlinearity,optical phased array,Coarse Wavelength Division Multiplexing (CWDM),multiplexing,LIDAR,silicon nitride,beam steering,frequency comb,grating coupler
更新于2025-09-23 15:22:29
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Spatial-Based Chipless RFID System
摘要： Conventional techniques in chipless RFID systems are incapable of fully overcoming the key challenges of modern identification applications, including high data capacity, low tag cost and reliable operation. The idea of electromagnetic (EM) imaging in chipless RFID systems is a promising technique that shows many advantages over other conventional approaches. This paper reviews conventional chipless RFID technology and provides a comprehensive analysis of advanced millimeter wave spatial-based (also known as image-based) chipless RFID systems with an optimized MIMO-SAR technique for high-resolution image acquisition and a quick reading process.
关键词： Multiple-input multiple-output (MIMO),Millimeter wave (mmwave),Chipless radio frequency identification (RFID),EM imaging,Virtual antenna array,Synthetic aperture radar (SAR)
更新于2025-09-23 15:22:29
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Phased Transmitarray Antennas for 1-D Beam Scanning
摘要： A transmitarray antenna (TAA) fed by a phased array antenna (PAA) for one-dimensional (1-D) beam scanning is proposed at 10 GHz in this letter. The TAA is composed of two types of elements, i.e., the hexagonal subwavelength low-pass elements as well as the pure dielectric ones. The PAA feed is a 1-D printed dipole array loaded with the short-circuited dummy ones. The proposed PAA-fed TAA, with a feeding distance to TAA diameter ratio (H/D) of mere 0.375, achieves a peak simulated gain of 25.6 dBi at 0o scanning (corresponding to peak aperture efficiency of 57.5%) and a 3.13 dB gain drop for ±30o beam scanning, along with a ~2-dB beam crossover. The measured results agree reasonably well with the simulated ones, validating the proposed design.
关键词： periodic structures,phased array antennas,transmitarray antennas,Beam scanning
更新于2025-09-23 15:22:29