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https://www.readbyqxmd.com/read/30322214/a-quadrature-single-side-band-mixer-with-passive-negative-resistance-in-software-defined-frequency-synthesizer
#1
Dongsheng Liu, Ang Hu, Kefeng Zhang
Software-defined radio (SDR) is a good solution for complying with the existing and incoming protocols for emerging wireless sensor networks (WSN) and internet of things (IoT) applications. The frequency synthesizer in a SDR tranceiver usually consists of a phase locked loop (PLL) and a post synthesizer. The PLL is the narrow band signal source and the post synthesizer generates wideband outputs by mixing and dividing. Compared with a frequency synthesizer utilizing the wideband PLL, this synthesizer features relatively constant loop parameters and mitigates the requirement for the oscillator...
October 14, 2018: Sensors
https://www.readbyqxmd.com/read/30320065/calibration-update-and-drift-correction-for-electronic-noses-and-tongues
#2
REVIEW
Alisa Rudnitskaya
One of the obstacles to the wider practical use of the multisensor systems for gas and liquid analysis-electronic noses and tongues, is the limited temporal validity of the multivariate calibration models. Frequent recalibration of multisensor systems is often excessively costly and time consuming due to the large number of necessary reference sample and their limited availability. There are several circumstances that can invalidate multivariate calibration model. The most common problem in the case of sensor systems is temporarily drift or gradual change of sensor characteristics occurring during sensor exploitation...
2018: Frontiers in Chemistry
https://www.readbyqxmd.com/read/30314369/mutually-coupled-time-to-digital-converters-tdcs-for-direct-time-of-flight-dtof-image-sensors
#3
Augusto Ronchini Ximenes, Preethi Padmanabhan, Edoardo Charbon
Direct time-of-flight (dTOF) image sensors require accurate and robust timing references for precise depth calculation. On-chip timing references are well-known and understood, but for imaging systems where several thousands of pixels require seamless references, area and power consumption limit the use of more traditional synthesizers, such as phase/delay-locked loops (PLLs/DLLs). Other methods, such as relative timing measurement (start/stop), require constant foreground calibration, which is not feasible for outdoor applications, where conditions of temperature, background illumination, etc...
October 11, 2018: Sensors
https://www.readbyqxmd.com/read/30314335/highly-sensitive-humidity-sensor-based-on-oblique-carbon-nanoplumes
#4
Siqi Qiao, Xiaoyan Peng, Lidan Wang, Shukai Duan, Jin Chu, Pengfei Jia
In this work, we fabricated three carbon nanoplume structured samples under different temperatures using a simple hot filament physical vapor deposition (HFPVD) process, and investigated the role of surface morphology, defects, and graphitic content on relative humidity (RH) sensing performances. The Van der Drift growth model and oblique angle deposition (OAD) technique of growing a large area of uniformly aligned and inclined oblique arrays of carbon nanoplumes (CNPs) on a catalyst-free silicon substrate was demonstrated...
October 11, 2018: Sensors
https://www.readbyqxmd.com/read/30312688/spatiotemporal-model-for-depth-perception-in-electric-sensing
#5
Babak Pourziaei, Gregory M Lewis, Huaxiong Huang, John E Lewis
Electric sensing involves measuring the voltage changes in an actively generated electric field, enabling an environment to be characterized by its electrical properties. It has been applied in a variety of contexts, from geophysics to biomedical imaging. Some species of fish also use an active electric sense to explore their environment in the dark. One of the primary challenges in such electric sensing involves mapping an environment in three-dimensions using voltage measurements that are limited to a two-dimensional sensor array (i...
October 9, 2018: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/30311609/cationic-polymer-based-plasmonic-sensor-array-that-discriminates-proteins
#6
Hongyan Xi, Xin Li, Qingyun Liu, Zhengbo Chen
Breaking the restrictions of a lock-and-key sensing strategy which relies only on the most dominant interactions between the sensing element and target, here, we develop a colorimetric sensor array with three kinds of cationic polymers (polydiallyl dimethylammonium chloride (PDDA), chitosan (CTS), and cetyltrimethylammonium bromide (CTAB)) as nonspecific receptors. Diverse interactions between cationic polymers and proteins make gold nanoparticles (Au NPs) exhibit different aggregation behaviors, resulting in changes in color and absorbance of Au NPs...
October 12, 2018: Analyst
https://www.readbyqxmd.com/read/30309021/multi-frequency-based-direction-of-arrival-estimation-for-2q-level-nested-radar-sonar-arrays
#7
Hao Zhou, Guoping Hu, Junpeng Shi, Ziang Feng
Direction finding is a hot research area in radar and sonar systems. In the case of q ≥ 2, the 2 q th-order cumulant based direction of arrival (DOA) estimation algorithm for the 2q -level nested array can achieve high resolution performance. A virtual 2q th-order difference co-array, which contains O ( N 2 q ) virtual sensors in the form of a uniform linear array (ULA), is yielded and the Gaussian noise is eliminated. However, some virtual elements are separated by the holes among the 2q th-order difference co-array and cannot be fully used...
October 10, 2018: Sensors
https://www.readbyqxmd.com/read/30308937/miniature-spectroscopes-with-two-dimensional-guided-mode-resonant-metal-grating-filters-integrated-on-a-photodiode-array
#8
Yoshiaki Kanamori, Daisuke Ema, Kazuhiro Hane
A small spectroscope with 25 color sensors was fabricated by combining metamaterial color filters and Si photodiodes. The metamaterial color filters consisted of guided-mode resonant metal gratings with subwavelength two-dimensional periodic structures. Transmittance characteristics of the color filters were designed to obtain peak wavelengths proportional to grating periods. For each color sensor, a peak wavelength of the spectral sensitivity could be tuned in the range of visible wavelengths by adjusting each grating period...
October 10, 2018: Materials
https://www.readbyqxmd.com/read/30307857/a-maximum-likelihood-approach-for-depth-field-estimation-based-on-epipolar-plane-images
#9
Alessandro Neri, Marco Carli, Federica Battisti
In this paper, a multi-resolution method for depth estimation from dense image arrays is presented. Recent progress in consumer electronics has enabled the development of low cost hand-held plenoptic cameras. In these systems, multiple views of a scene are captured in a single shot by means of a micro-lens array placed on the focal point of the first camera lens, in front of the imaging sensor. These views can be processed jointly to obtain accurate depth maps. In this contribution, to reduce the computational complexity associated to global optimization schemes based on match cost functions, we make a local estimate based on the maximization of the total log-likelihood spatial density aggregated along the epipolar lines corresponding to each view pair...
February 2019: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
https://www.readbyqxmd.com/read/30303203/multi-segmented-cds-au-nanorods-for-electrochemiluminescence-bioanalysis
#10
Xiao-Lei Huo, Hui Yang, Mei-Xing Li, Wei Zhao, Jing-Juan Xu, Ying Wang, Xi-Liang Luo, Hong-Yuan Chen
In this study, we have developed a programmable electrochemiluminescence (ECL) system based on multi-segmented CdS-Au nanorod arrays with a sequential and highly tunable structure. The nanorod arrays were synthesized by an electrodeposition method using anodic aluminum oxide (AAO) as the template in which the Au and CdS segments were alternately electrodeposited. Compared to pure CdS nanorod arrays, multi-segmented CdS-Au nanorod arrays have showed a better ECL performance, which can be attributed to two factors: the favorable electron transfer and the surface plasma resonance (SPR) effect of the Au segment...
October 10, 2018: Nanoscale
https://www.readbyqxmd.com/read/30302487/an-integrated-adipose-tissue-on-chip-nanoplasmonic-biosensing-platform-for-investigating-obesity-associated-inflammation
#11
Jingyi Zhu, Jiacheng He, Michael Verano, Ayoola T Brimmo, Ayoub Glia, Mohammad A Qasaimeh, Pengyu Chen, Jose O Aleman, Weiqiang Chen
Although many advanced biosensing techniques have been proposed for cytokine profiling, there are no clinically available methods that integrate high-resolution immune cell monitoring and in situ multiplexed cytokine detection together in a biomimetic tissue microenvironment. The primary challenge arises due to the lack of suitable label-free sensing techniques and difficulty for sensor integration. In this work, we demonstrated a novel integration of a localized-surface plasmon resonance (LSPR)-based biosensor with a biomimetic microfluidic 'adipose-tissue-on-chip' platform for an in situ label-free, high-throughput and multiplexed cytokine secretion analysis of obese adipose tissue...
October 10, 2018: Lab on a Chip
https://www.readbyqxmd.com/read/30301980/efficient-and-sensitive-electrically-small-rectenna-for-ultra-low-power-rf-energy-harvesting
#12
Stylianos D Assimonis, Vincent Fusco, Apostolos Georgiadis, Theodoros Samaras
A new electrically small antenna with size ka = 0.415 is presented, fabricated and measured in this work. This is intrinsically matched to 50 Ω, has omni-directional and linear-polarized radiation pattern in the horizontal plane with maximum directivity of 1.75 dBi and simulated radiation efficiency of 93%. The antenna in combination with a low-complex and co-planar rectifier with one single diode forms a high efficient and sensitive electrically small rectenna with ka = 0.53 at 868 MHz (UHF RFID-band in Europe)...
October 9, 2018: Scientific Reports
https://www.readbyqxmd.com/read/30301552/nonlinear-scattering-and-mode-conversion-of-lamb-waves-at-breathing-cracks-an-efficient-numerical-approach
#13
Yanfeng Shen, Carlos E S Cesnik
This article presents an efficient numerical approach to the investigation of nonlinear scattering and mode conversion phenomena of Lamb waves as they interact with breathing cracks. A Local Interaction Simulation Approach (LISA) is adopted, which possesses the versatility to capture arbitrary damage profiles. The stick-slip contact dynamics is implemented in the LISA model via the penalty method, which captures the nonlinear interactions between Lamb waves and breathing cracks. The LISA framework achieves remarkable computational efficiency with its parallel implementation using Compute Unified Device Architecture (CUDA) executed on powerful GPUs...
September 25, 2018: Ultrasonics
https://www.readbyqxmd.com/read/30301258/ltcc-packaged-ring-oscillator-based-sensor-for-evaluation-of-cell-proliferation
#14
Joni Kilpijärvi, Niina Halonen, Maciej Sobocinski, Antti Hassinen, Bathiya Senevirathna, Kajsa Uvdal, Pamela Abshire, Elisabeth Smela, Sakari Kellokumpu, Jari Juuti, Anita Lloyd Spetz
A complementary metal-oxide-semiconductor (CMOS) chip biosensor was developed for cell viability monitoring based on an array of capacitance sensors utilizing a ring oscillator. The chip was packaged in a low temperature co-fired ceramic (LTCC) module with a flip chip bonding technique. A microcontroller operates the chip, while the whole measurement system was controlled by PC. The developed biosensor was applied for measurement of the proliferation stage of adherent cells where the sensor response depends on the ratio between healthy, viable and multiplying cells, which adhere onto the chip surface, and necrotic or apoptotic cells, which detach from the chip surface...
October 7, 2018: Sensors
https://www.readbyqxmd.com/read/30298635/detecting-counterfeit-brandies
#15
Benhua Wang, Jinsong Han, Hao Zhang, Aike Biella, Markus Bender, Kai Seehafer, Uwe Heiko Bunz
A hypothesis free sensor array (optoelectronic tongue) composed of an anionic, a cationic and two neutral poly(para-aryleneethynylene)s (PAE) at pH 3, 7 and 13 discriminate more than 30 spirits (including brandy, Branntwein, Cognac, Spirituose, and Weinbrand). Counterfeits (made by mixing of low quality spirits and caramel colour) and different batches of identical brands of brandies are discriminated. The sensor array works without sample preparation or great instrumental cost and is superior to conventional methods with respect to sample need (10-20 μL), time and effort...
October 8, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/30297843/solution-processes-for-ultrabroadband-and-omnidirectional-graded-index-glass-lenses-with-near-zero-reflectivity-in-high-concentration-photovoltaics
#16
Junwen He, Yuan Yao, Kyu-Tae Lee, Nina Hong, Brent Fisher, Rabab R Bahabry, Jung Woo Lee, Jeonghyun Kim, Seungyong Han, Sanjay V Kalidindi, Jae-Hwan Kim, Sung Bong Kim, Jaewon Choi, Hongwoo Jang, Myeong Namkoong, Scott Burroughs, Muhammad Hussain, Ralph G Nuzzo, John A Rogers
Concentrator photovoltaic (CPV) systems, where incident direct solar radiation is tightly concentrated onto high-efficiency multi-junction solar cells by geometric optical elements, exhibit the highest efficiencies in converting the sun's energy into electric power. Their energy conversion efficiencies are greatly limited, however, due to Fresnel reflection losses occurring at three air/optics interfaces in the most sophisticated dual-stage CPV platforms. This paper describes a facile one-step wet-etching process to create a nanoporous surface with a graded-index profile on both flat and curved glasses, with capabilities of achieving ~99% average transmission efficiency in a wide wavelength range from 380 nm to 1...
October 8, 2018: Scientific Reports
https://www.readbyqxmd.com/read/30297798/battery-operated-integrated-frequency-comb-generator
#17
Brian Stern, Xingchen Ji, Yoshitomo Okawachi, Alexander L Gaeta, Michal Lipson
Optical frequency combs are broadband sources that offer mutually coherent, equidistant spectral lines with unprecedented precision in frequency and timing for an array of applications1 . Frequency combs generated in microresonators through the Kerr nonlinearity require a single-frequency pump laser and have the potential to provide highly compact, scalable and power-efficient devices2,3 . Here we demonstrate a device-a laser-integrated Kerr frequency comb generator-that fulfils this potential through use of extremely low-loss silicon nitride waveguides that form both the microresonator and an integrated laser cavity...
October 8, 2018: Nature
https://www.readbyqxmd.com/read/30296826/fluorescent-gold-nanocluster-based-sensor-array-for-nitrophenol-isomer-discrimination-via-an-integration-of-host-guest-interaction-and-inner-filter-effect
#18
Hongwei Yang, Fengniu Lu, Ye Sun, Zhiqin Yuan, Chao Lu
The rapid discrimination of nitrophenol isomers has been a long-standing challenge because of the tiny structural differences among the isomers. In this study, a fluorescent sensor array based on three different-color emitting gold nanoclusters (Au NCs) that were functionalized with three different ligands and a co-capping ligand β-cyclodextrin (β-CD) has been constructed for the facile discrimination of three nitrophenol isomers via the linear discriminant analysis of isomer-induced fluorescence quenching patterns...
October 9, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/30296220/sparse-convolutional-beamforming-for-ultrasound-imaging
#19
Regev Cohen, Yonina C Eldar
The standard technique used by commercial medical ultrasound systems to form B-mode images is delay and sum (DAS) beamforming. However, DAS often results in limited image resolution and contrast, which are governed by the center frequency and the aperture size of the ultrasound transducer. A large number of elements leads to improved resolution but at the same time increases the data size and the system cost due to the receive electronics required for each element. Therefore, reducing the number of receiving channels while producing high quality images is of great importance...
October 8, 2018: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/30295303/a-novel-and-accurate-microfluidic-assay-of-cd62l-in-bladder-cancer-serum-samples
#20
Gayatri S Phadke, Jennifer E Satterwhite-Warden, Dharamainder Choudhary, John A Taylor, James F Rusling
We report a low-cost, sensitive, bead-based electrochemical immunoarray for soluble L-selectin (or CD62L protein), a potential biomarker for staging bladder cancer. We used a semi-automated modular microfluidic array with online antigen capture on superparamagnetic beads, which were subsequently delivered to a detection chamber housing multiple sensors. The assay was designed to accurately detect CD62L in diluted serum with a limit of detection (LOD) of 0.25 ng mL-1 and a dynamic range of 0.25-100 ng mL-1. The microfluidic array gave significantly better accuracy and higher sensitivity than a standard ELISA kit, which was shown to be subject to significant systematic error at high and low concentration ranges...
October 8, 2018: Analyst
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