bluuebunny/crossref_metadata_2025 huggingface dataset:
RF Load Board Tuning With 93K Feature
Authors: Yan Zexin
Published: March 2012

RF load boards are used as interface between DUT (device under test) and ATE tester. Its performance affects correlation with Bench and production yield rate directly. But issues from load board design and production can possibly involve problems. Performance usually is not as good as expected. For mass production different load boards from same design need show similar performance, the tolerance for them is very tight. That's why tuning for RF load board is so important. But tuning itself is not strict forward as school book, no accurate model for micro strip, lump components, and normally no accurate S parameters for DUT. It's time consuming and usually a procedure of trial by error. In this paper, transmission theory, Smith chart tool, which are useful for match circuits design are quickly reviewed. Then introduce how to design match circuits, which structure can be used, how many components are needed, what factors should be considered. Finally by demonstrating an example in real case, author tries to explain how to perform RF load board tuning with 93K ATE tester.
Endpoint Detection in Plasma Etching Using Principal Component Analysis and Support Vector Machine
Authors: Han Yi-Seul , Park Young-Kook , Hong Sang-Jeen , Han Seung-Soo
Published: March 2012

Since semiconductor devices are extremely integrated, process control is much more difficult in semiconductor fabrication. The optical emission spectroscopy (OES) acquires unique wavelength intensity of particles in plasma chamber, and the endpoint can be decided by utilizing its intensity. However, the endpoint detection is difficult because not only of these tremendous amount of data, but also of extremely large amount of noise in OES data. To solve these problems, the OES data of by-products and the data of etchants are classified by SNR. And a combination of Principal Component Analysis (PCA) and Support Vector Machine (SVM) hybrid algorithm is applied to detect endpoint. The PCA was utilized to reduce dimension of the selected data, and SVM algorithm is applied to separates status between before endpoint and after endpoint. The SVM model using SNR and PCA showed excellent performance in real-time endpoint detection in plasma etching.
Endpoint Detection in Low Open Area Ratio Plasma Etching Using Hybrid Method
Authors: Kim Seung-Gyun , Jeon Sung-Ik , Han Yi-Seul , Shin Sung-Hwan , Hong Sang-Jeen , Han Seung-Soo
Published: March 2012

In current semiconductor manufacturing, as the feature size of integrated circuit (IC) devices continuously shrinks, detecting endpoint in low open area plasma etch process is more difficult than before. For endpoint detection, various kinds of sensors are installed in many semiconductor manufacturing equipment, and sensor data sampled with predefined sampling rate. To solve this problem, a combination of Signal to Noise Ratio (SNR), Principal Component Analysis (PCA) and Expanded Hidden Markov model (eHMM) technique is applied to optical emission spectroscopy (OES) signals.
Endpoint Detection Strategy in Bosch Process Using PCA and HMM
Authors: Jeon Sung-Ik , Kim Seung-Gyun , Han Yi-Seul , Shin Sung-Hwan , Han Seung-Soo
Published: March 2012

Bosch process is developed for advanced microstructure devices and etch endpoint detection (EPD) is demanded for 'notching' (as feature profile degradation) or reducing thickness of the underlying stop. One method commonly used to detect plasma process endpoint is utilizing optical emission spectrometry (OES) sensor. OES analyzes the light emitted from plasma source to draw inferences about the chemical and physical state of the plasma process. In this paper, an endpoint detection algorithm conjunction with Principal Component Analysis (PCA) and extended Hidden Markov Model (eHMM) using OES signal in Bosch process is proposed. PCA is used to reduce dimension of data without information loss and eHMM is applied to correctly detect endpoint. In 120 um TSVs, this work shows excellent performance.
Calibration of 25-nm Pitch Grating Reference by X-ray Diffraction
Authors: Ito Yoshiyasu , Omote Kazuhiko
Published: March 2012

We have developed grazing incidence x-ray diffraction pitch calibration system with wavelength of 0.1540593 nm (Cu Kα1 line). In order to ensure consistency of this calibration system with currently used deep ultra violet (DUV) laser diffraction pitch calibration system, we measured average pitch of a 100-nm pitch grating reference for CD-SEM. The average pitch determined by the x-ray diffraction agreed with that determined by the DUV laser diffraction within the range of expanded uncertainty. We measured average pitch of a next generation 25-nm pitch grating for which DUV laser no longer works. We have successfully detected more than ten sharp diffraction peaks corresponding to the 25-nm period. The average pitch of the grating was measured in high-accuracy with expanded uncertainty of 40 pm. The result agreed well with that determined by metrological atomic microscope (AFM) within the range of expanded uncertainty.
In-Line Inspection on Thickness of Sputtered Thin Ta and TaN Films by Spectroscopic Ellipsometry
Authors: Yuan Chao , Kang Xiaoxu , Zuo Qingyun , Zeng Shaohai , Chen Shoumian , Zhao Yuhang
Published: March 2012

An optical method utilizes spectroscopic and ellipsometry(SE) technique is developed to measure thin metal thickness below 300A. Repeated tests have been made on various TaN or Ta films to check the stability. Sheet resistance of the films has been measured by four-point probe to check the correlation. TEM analysis has been made to check the accuracy of the measurement. The results match well with TEM and show good repeatability and reproducibility(R&R) performance for 100A and 200A Ta or TaN film deposited directly on silicon substrate, which indicates the possibility for the process monitor of thin metal films.
A Method of Relative Calibration Developed for very High Consistency of Internal Metrology Standards
Authors: Yang Siyuan F.
Published: March 2012

A method of relative calibration is developed in this work to calibrate the golden Standard wafers (VLSI Standard or self-prepared Standard wafers) from each geographical site to achieve very high consistency across all sites with relevant factors under control which otherwise might affect such calibration processes. These golden wafers from all sites are calibrated against a Master golden wafer which was chosen with the smallest expanded uncertainty. The derived expanded uncertainty of each golden wafer calibrated this way relative to the Master golden wafer has proved to be much smaller than the expanded uncertainty of the Master VLSI Standard wafers which were accredited by National Voluntary Laboratory Accreditation Program and is also traceable to NIST Standards. The very high consistency among all thus calibrated golden wafers from all geographical sites respectively are therefore achieved with almost the same relative accuracy as the one obtained with the Master golden wafer travelling across all sites.
Effect of Finger and Device-Width on Ruggedness of nLDMOS Device under Single-Pulse Unclamped Inductive Switching (UIS) Conditions
Authors: Agarwal Neelam , Sharma Karuna N. , Tsai Jung-Ruey , Basavalingappa Adarsh , Sheu Gene , Yang Shao-Ming
Published: March 2012

This work demonstrates the effect of increasing finger number and width on the ruggedness of the nLDMOS device under test (DUT). The ruggedness or energy handling capability is analyzed by two-dimensional (2-D) and three dimensional (3-D) device and circuit simulations. The set failure criterion in our study and simulation is the device temperature reaching a critical value equal to the melting point of metal-contacts. The maximum energy is calculated by considering the pass-case prior to device failure and time-integrating the drain voltage and current for the avalanche duration. Maximum avalanche energy handling capability is seen to be increased linearly with number of device fingers. UIS test was also performed on width extended multi-finger nLDMOS device structures. The simulated results provided useful approaches to predict real experimental results and contribute to their physical interpretation by identification of the mechanism of device-failure, hot-spot location and continuous temperature extraction.
The Effect of Nitrogen on the Energy Distribution of Hole Traps Generated under Negative Bias Temperature Stress
Authors: Liao Yiming , Ji Xiaoli , Hu Yue , Yan Fen , Shi Yi , Zhang Guan , Guo Qiang
Published: March 2012

Abstract- We use low temperature measure technique to identify the energy distribution profile of recoverable hole traps, created under Negative Bias Temperature stress in PNO pMOSFETs. It is found that the energy distribution profile is quite similar as that in SiO2 devices after long time NBT stress. The results could be explained that the nitrogen in SiO2 gate oxide doesn't generate new type recoverable hole traps distribution within the Si bandgap under NBT stress.
A Study On The Dielectric Intrinsic Breakdown Specification
Authors: Han Kun , Zhao Yong A. , Guo Qiang , Chien Wei-Ting Kary
Published: March 2012

With the introduction of ultra-thin gate oxides (GOXs) and low-k dielectrics into IC manufacturing, some new dielectric failure mechanisms arisen. These changes make the evaluations of dielectric reliability more complex. We propose a new method to accurately define the dielectric intrinsic breakdown specification (Spec) of V-ramp (Voltage ramp) tests. Base on the physical failure process and statistical correlation between V-ramp and TDDB (Time Dependent Dielectric Breakdown) tests, the applicability of our proposed method can be further extended to ultra-thin GOX and low-k dielectrics. A quicker and more accurate judgment on dielectric reliability can be achieved by using our method to better assess dielectric reliability risk.
Worst Case Stress Conditions for Hot Carrier Degradation with Technology Nodes from 0.35µm to 45nm
Authors: Chen Zhaoxing , Ji Xiaoli , Yan Fen , Shi Yi , Song Yongliang , Wu Jeff , Guo Qiang
Published: March 2012

The worst case stress conditions for hot carrier degradation have been investigated in detail at the devices fabricated with CMOS technologies from 0.35µm to 45nm. In nMOSFETs with long channel devices (L>0.18µm), Vg at Ibmax and the lowest temperature is the worst case condition; For short channel devices (0.13 µm ≤ L ≤ 0.18μm), Vg @ Ibmax and Vg=Vd stress conditions result in comparable hot carrier damage; For the very short channel transistors (L<0.13µm), the worst case stress condition has been found to be Vg=Vd instead of Vg@Ibmax. In this case, the higher temperature will induce worse hot carrier degradation. In pMOSFETs, the stress conditions Vg@Igmax is the worst case condition for the long channel devices (L≥0.35µm). As the channel length scaled to sub-0.25µm, the worst case stress condition shifts from Vg@Igmax to VG = VD.
Critical Dimension Measurement Using OCD Spectroscopy for Gate and STI AEI Structures
Authors: Zhang Zhen Sheng , Huang Yi , Feng Yong-Gang , Lee Charles , Gao Hai-Jun , Chen Hui-Ping , Dang Jiang-Tao , Li Hai-Tao , Shi Yaoming , Xu Yiping
Published: March 2012

In this work, optical critical dimension (OCD) spectroscopy was used to monitor the critical dimension for gate and STI AEI (After-Etch Inspection) structures. The reference measurements with CD-SEM (CD Scanning Electron Microscope) and TEM (Transmission Electron Microscopy) were also carried out. The OCD results show high precision, high stability and good correlation. This work demonstrates the capability of the OCD as an important metrology technique for IC process control.
Advanced Inspection Technique for High Aspect Ratio Contact Holes Using e Beam Scan and Voltage Cap in SEM Review
Authors: Liao Hsiang-Chou , Hung Che-Lun , Luoh Tuung , Yang Ling-Wu , Yang Tahone , Chen Kuang-Chao , Lu Chih-Yuan
Published: March 2012

The inspection strategy and technique of high aspect ratio contact modules are demonstrated in this paper. Pre-scan with dark or bright field inspection then reviewing by Vcap condition at contact opening layer is to confirm the HAR contact patterning performance. e beam inspection with feasible conditions right after plug CMP is to monitor the whole contact module and the plugs fill-in performance.
Performance Evaluation of the MOHOS Flash Memory with Fluorinated HfO2 Charge Storage Layer Using Gate Fluorine Ion Implantation
Authors: Chen Yung-Yu , Lei Gen
Published: March 2012

Electrical characteristics improvement of the fluorinated metal/SiO2/HfO2/SiO2/Si (MOHOS) flash memory using gate fluorine ion implantation (GFI) process has been investigated. Si-F or Hf-F bonds formation due to fluorine incorporation can reduce undesirable charges trapping and leakage path creation in the tunneling oxide, which consequently increases the program/erase (P/E) speed and endurance. Moreover, fluorinated flash memory not only enhances P/E efficiency, but also improves the data retention characteristic, which can be explained by more deep-level traps and reduced leakage path due to fluorine incorporation. P/E window closure during endurance stressing is significantly suppressed for the fluorinated flash memory, which can be also ascribed to stronger Si-F or Hf-F bonds formation within the dielectrics due to fluorine incorporation. However, the fluorinated MOHOS flash memory clearly exhibits apparent erase-saturation phenomenon due to higher electric field across on blocking oxide. The results clearly indicate the fluorinated flash memory using GFI process to simultaneously fabricate fluorinated OHO dielectrics becomes a feasible technology for future MOHOS-type nonvolatile flash memory application.
Research of Bilayer Stacked Resistance Switching Memory Structure Based on Pt/NiO/TiO2/Pt
Authors: Rite E. , Zhang Kailiang , Wang Fang , Wei Xiaoying , Liu Kai , Zhao Jinshi
Published: March 2012

The large power consumption and the wide distribution of switching parameters for unipolar resistance switching are major hurdles to non-volatile memory application. In this letter, the stacked structure Pt/NiO/TiO2/Pt was investigated to overcome the mentioned problems. TiO2 thin film was formed on NiO by oxidation of metallic Ti thin film through rapid thermal process (RTP) in oxygen atmosphere. The sharp TiO2 (202) peak and NiO (200) peak observed by the X-ray diffraction measurement. This stacked bilayer structure is favorable for reducing reset current in comparison with single layer structure. This is attributed to a small amount of heat loss during rupturing process of conductive filaments. It is suggested that the conductive filament rupture and rejuvenation was happened at the interface between TiO2 and NiO by controlling switching sequence. Furthermore, the diffused Ti in NiO also can result in stabilization of switching parameters.
Phase Change Memory Modeling: From Chalcogenide Physics to Device Scaling
Authors: Ielmini Daniele
Published: March 2012

Phase change memory (PCM) based on the electrically-induced phase transition in chalcogenide materials is an emerging device capable of fast switching and nonvolatile storage, thus potentially allowing to meet both the specifications of DRAM and Flash devices. To develop fast and scalable PCMs, the conduction and reliability physics must be carefully understood and physically-accurate models must be identified. In this work, recent advances about the physical modeling of PCM devices will be reviewed. The electrical transport mechanisms, needed to predict the scaling dependence of resistance window, will be described. The scaling trend of reset current will be discussed with reference to the existing cell architectures (i.e. mushroom, pore and line cells).
A CMOS Compatible WOx RRAM with Optimized Switching Operations
Authors: Bai Yue , Wu Huaqiang , Chen Hualun , Chen Guanglong , Chen Haoyu , Qian He
Published: March 2012

The tungsten oxide (WOx) RRAM devices using 0.18μm CMOS process are designed, fabricated and characterized. The process flow is completely compatible with CMOS back-end-of-line process which is presented in this paper. In order to understand the switching mechanism and improve the memory cell performance, various process conditions have been studied and compared. The RRAM cell exhibits good memory properties, such as: fast set and reset speed (<20ns), low operation voltage (<4V), high switching uniformity, and good endurance characteristics. It is also observed that different operation conditions can affect the RRAM cell switching properties significantly. The trade-off between performances and tolerable operation conditions is discussed.
Reducing Formation Time of the Inversion Layer by Illumination around a Memory Capacitor
Authors: Jin Lin , Zhang Manhong , Huo Zongliang , Yu Zhaoan , Wang Yong , Chen Junning , Liu Ming
Published: March 2012

Capacitor structures are often used to evaluate the program and erase characteristics of charge trapping memory devices. Due to thermally generation of a few minority carriers, the operation efficiency of memory devices is underestimated for the weak response to the formation of inversion layer. In this paper, illumination around a memory capacitor is introduced. Experiment results show that illumination reduces the formation time of the inversion layer and thus increase the program/erase efficiency. Thereby, it is more accurate to characterize program/erase transients of memory devices with capacitor structures under illumination.
Improvement of Performance of Dye-Sensitized Solar Cell by Using Composite Nanoparticulate Photoelectrode Films
Authors: Liu Lifeng , Li Boyang , Yang Fei , Wang Xu , Wang Yi , Kang Jinfeng , Zhang Xing
Published: March 2012

Photoelectrodes using different nanoparticle size and film thickness of TiO2 were prepared by screen-printing and post annealing method with the objective of optimizing the photovoltaic performance of dye-sensitized solar cells (DSSCs). The effect of nanoparticle size and film thickness of the TiO2 on the performance of DSSCs was investigated. Based on the effect investigation, composite nanoparticulate TiO2 film electrodes were designed and fabricated to improve the photovoltaic performance of the DSSCs. The enhanced conversion efficiency was achieved in the DSSCs by introducing light scattering layer and additional dye adsorption nanoparticle layer to form composite TiO2 films, and by optimizing the nanoparticle size and film thickness. The improvement mechanism was also discussed.
Hydrogenated Microcrystalling Silicon Single-Junction NIP Solar Cells
Authors: Xu Juan , Zhang Kailiang , Yuan Yujie , Geng Xinhua , Wang Fang , Miao Yinping
Published: March 2012

The microstructure properties of hydrogenated microcrystalline silicon solar cells are investigated using Raman spectroscopy and x-ray diffraction. It was found that the increase of grain size and crystalline volume fraction with thickness is the main reason for the deterioration of cell performance as using constant hydrogen dilution technique. In order to adjust grain size and crystalline volume fraction along the growth direction, gradient hydrogen dilution technique has been adopted to control the structural evolution. The experiment results demonstrated that the performance of solar cell can be much improved when there's a higher crystallinity at n/i interface and a lower crystallinity at i/p interface. We have achieved an initial active-area efficiency of 5.7% (Voc=0.47V, Jsc=20.2mA/cm2, FF=60%) for the µc-Si:H single-junction n-i-p solar cells.
Wafer Bonding for Backside Illuminated Image Sensors
Authors: Matthias Thorsten , Uhrmann Thomas , Dragoi Viorel , Wagenleitner Thomas , Lindner Paul
Published: March 2012

Backside illuminated image sensors combine small pixel area with high signal-to-noise ratio. Wafer bonding is a key enabling process step for manufacturing of backside illuminated image sensors. The fully CMOS processed image sensor wafer is bonded to a blank silicon carrier wafer and then back thinned to reveal the photodiodes. As a result the photodiodes are on top of the metal interconnects thereby eliminating any shading of the photosensitive area. Plasma activated fusion wafer bonding enables a room temperature wafer bonding with highest wafer-to-wafer alignment accuracy.
Evaluation of Interfacial State Density of MOS Capacitor with Three-Dimensional Channel by Conductance Method
Authors: Li Wei , Nakajima Kazuhiro , Dou Chunmeng , Kakushima Kuniyuki , Ahmet Parhat , Nishiyama Akira , Sugii Nobuyuki , Tsutsui Kazuo , Kataoka Yoshinori , Natori Kenji , Hattori Takeo , Iwai Hiroshi
Published: March 2012

An investigation of interface state density of three-dimensional channel MOS capacitor was carried out by conductance method. A comparison of Gp/ω of 3D-channel device with planar device was presented. Surface potential distribution of 3D-channel device was explained by simulation. A tendency of interface state density as the height of Fin changes on the flat band condition was obtained.
Influence of Substrate Temperature on Properties of Indium Tin Oxide Thin Films Prepared by DC Magnetron Sputtering
Authors: Xu Juan , Yuan Yujie , Wang Fang , Zhang Kailiang
Published: March 2012

In this paper, the influence of substrate temperature on structure, optical and electrical properties of the Indium tin oxide films has been investigated. ITO films were prepared on eagle 2000 glass substrates by DC reactive magnetron sputtering. The results demonstrated that the electrical properties of ITO films changed significantly with the substrate temperature. The optical transmittance of all samples in the visible range was beyond 80%. By a further study on the transmittance, the optical band gap for ITO from 3.81 to 3.66 can be obtained from mapping by to hv. The ITO grain size was increased with the substrate temperature rising.
New Dynamics of the MEMS Inertial Sensor Market
Authors: Robin Laurent
Published: March 2012

We will present our new market forecast 2010-2016 for MEMS inertial sensors. The consumer and automotive inertial sensors market saw a healthy 15% growth in 2011 to surpass a $2.7 billion business, thanks to the increasing penetration of more motion sensing into more mobile devices and more automotive safety systems in more cars across the globe. The market and technology trends will be detailed. We will focus on the development of sensor combos. The key drivers to integrate several MEMS sensors in a package are to provide cost / size decrease, or to provide new functionalities with sensor fusion. We will see that sensor fusion with specific software brings a lot of the value, because MEMS players are now trying to sell functions rather than sensors. Lastly we will focus on describing the leading players and the hot developments in this area. The development of MEMS combos implies new business models which are shaking the MEMS industry. The complexity of the inertial MEMS supply chain and the major evolutions will be highlighted in this presentation.
MEMS Technology and Market Trends - Change of Supply Chain and Business Models, Focus on MEMS Microphone Market
Authors: Ding Wenbin
Published: March 2012

Yole Développement now expects the sector to see 16% growth in 2011, to reach a $10.0 billion market this year. After three relatively flat years in 2007 to 2009, final figures indicate total MEMS sales jumped some 25% in 2010, to $8.6 billion, thanks largely to the surprisingly fast recovery of the automotive industry and its inventory restocking, as well as the boom in smart phones and tablets with motion sensing. But stronger than anticipated sales of optical MEMS for both telecommunications and consumer applications, and of inertial and RF devices for industrial applications also contributed to the outsize growth. Though growth will now settle down to more sustainable post-recovery rates, we now expect continued stronger demand across these multiple sectors to drive 14% compound annual growth for the MEMS industry for the next five years, to reach a $19.5 billion market by 2016.
Realization of a μPCR System and Its EC Detection Circuits
Authors: Guo Cangran , Wang J. Q. , Zhang Pu , Deng Tao , Guo Xin , Dai T. J. , Liu Zewen
Published: March 2012

A μPCR system and its Electrochemical (EC) detection circuits are presented. The system consists of a μPCR chip packaged on a printed circuit board (PCB), peripheral signal read-out circuits and control circuits. The μPCR chip is realized with MEMS-technology contains an array of 3×4 reaction chamber. A microcontroller unit (MCU) is used in the control system to monitor the reaction procedure (PCR cycling) and handle the signal measurement. A Logarithmic Current Mode Amplifier (LGCMA) is proposed and realized as the EC signal amplification and I-V conversion. The test results shows that the obtained chip presents good Logarithmic DC characteristics within a current change from 1nA to 1μA and the corresponding output is from -4.43V to -3.52V. Thermal cycling experiment was carried to verified the control system, The results show that the variation of temperature is 0.1°C at the stable state.
Next Generation Photovoltaic Cells and System through MEMS Technology
Authors: Nielson Gregory N. , Okandan Murat , Cruz-Campa Jose L. , Resnick P. R. , Sanchez Carlos A. , Sweatt William C. , Lentine Anthony L. , Gupta Vipin P. , Nelson Jeffrey S.
Published: March 2012

We report on the application of MEMS and other microsystem technologies to photovoltaic (PV) cells, modules, and systems to take advantage of the numerous, significant beneficial effects that are realized as the size of solar cells decrease to sub-mm length scales. To demonstrate these effects, we have developed both crystalline silicon and III-V PV cells. These cells are from 2 to 20 microns thick and from 250 microns to one millimeter across. We have demonstrated conversion efficiencies of up to 14.9% for a 14 micron thick crystalline silicon PV cell. This work provides benefits for two broad PV applications: 1) highly flexible PV modules with conversion efficiencies greater than 20%, and 2) commercial/utility scale PV systems using moderate concentration flat plate modules with simple single-axis or coarse dual-axis tracking. Cost models indicate that systems based on these technologies can achieve unsubsidized energy costs of less than $0.10/kWh.
Trace Detection of Energetic Substances Using Silicon Dioxide Microbridge-Based Micro-Calorimetric Sensors
Authors: Ruan Wenzhou , Wang Zheyao , Li Yuanchao , Tan Zhimin , Liu Litian
Published: March 2012

A microbridge based calorimetric sensor is developed for the detection of trace energetic substances by measuring their characteristic temperature change in thermal reactions. The micro-calorimeter is mainly a suspending microbridge made of silicon dioxide (SiO2) and integrated with heating and detecting resistors. It is fabricated based on silicon-on-insulator (SOI) wafers using a front-side releasing method, which is simple, efficient and high-yielding. The tiny microbridge is with an extremely low dimension and achieves low thermal capacity, allows small temperature changes induced by chemical reactions detectable. A limit of detection of sub-100 pg is demonstrated for trinitrotoluene (TNT) by measuring the endothermic and exothermic reactions when heating the preconcentrated TNT to the deflagrating temperature, indicating the ability of the sensors in energetic chemical detection.
RF MEMS Switch and Its Applications
Authors: Liu Zewen , Li Ling
Published: March 2012

RF MEMS (Radio Frequency Microelectromechanical System) has seen an amazing growth in the past 20 years. It has immense commercial and defense potential due to its low loss, low power consumption and superior RF performances. In this article, RF MEMS and its applications are reviewed. Special emphasis is on the RF MEMS switches and MEMS phase shifters investigated in IMETU (Institute of Microelectronics of Tsinghua University). A variety of RF MEMS switches with different configurations are introduced. The MEMS switch present unique properties for the application in future miniaturized antenna and radar system. The prototype illustrates the RF MEMS switch as a fundamental structure in signal path control, structural optimization, and match circuits is very promising to be used in future reconfigurable radar and antenna system, which will address to the application not only in the mobile terminal but also the high end wireless sensor network.
Nano Electro Mechanical Devices for Physical and Chemical Sensing
Authors: Polizzi Jean-Philippe , Duraffourg Laurent , Ollier Eric , Arcamone Julien , Robert Philippe
Published: March 2012

The emergence of MEMS in consumer applications has dramatically increased market perspectives but also puts very strong constraints on cost and integration issues. Addressing these issues through further size reduction is not always relevant as it does not allow maintaining a correct signal to noise ratio (SNR) for the ubiquitous capacitive MEMS sensors. Different solutions are presented here according to the nature of the signal to be sensed: For physical sensors a new concept mixing a micron sized proof mass and a nano-sized detection structure is described. For chemical sensors, the reduction in size actually presents some advantages in terms of high resonant frequency, reduced gas damping, and high sensitivity to applied forces or added mass. Application of nano-resonators to gaz sensing is depicted.
Well Aligned Single-Walled Carbon Nanotube (SWNT) Film as a Building Block for MEMS/NEMS Devices
Authors: Wang Baoming , Rong Hao , Lu Miao
Published: March 2012

SWNTs are among the strongest known fibers with low density, high thermal conductivity, high piezoresistivity, and can survive in 2-300 ° in oxygenic environment and ~ 900 ° in vacuum. Some fundamental MEMS/NEMS components, especially beams and cantilevers, will have broad applications if they are made of aligned dense SWNTs. In this paper, a fabrication process of SWNT nanoscale beams and cantilevers are presented, and some application examples like microfluidic devices are introduced.
Research on Silicon PIN Neutron Dose Detector
Authors: Fan Chao , Yu Min , Yang Fangdong , Tian Dayu , Wang Jinyan , Jin Yufeng
Published: March 2012

Two batches of Si PIN diodes, with different area, are fabricated. The silicon resistivity is 2kΩ•cm and 20kΩ•cm respectively for the two batches. The response of the diodes to 239Pu-Be isotopic neutron source, whose average energy is ~4.5 MeV, is measured. The change of the forward I-V curve after radiation is studied. The experimental results indicate that the diode with high resistivity biased at high level injection is more sensitive to the neutron radiation. It is also shown that, the sensitivity increases as the geometry size increases at low neutron dose, but decreases when the neutron dose gets high enough.
The “systolic volume balance” method for the noninvasive estimation of cardiac output based on pressure wave analysis
Authors: Papaioannou Theodore G. , Vardoulis Orestis , Stergiopulos Nikos
Published: March 2012

Cardiac output (CO) monitoring is essential for the optimal management of critically ill patients. Several mathematical methods have been proposed for CO estimation based on pressure waveform analysis. Most of them depend on invasive recording of blood pressure and require repeated calibrations, and they suffer from decreased accuracy under specific conditions. A new systolic volume balance (SVB) method, including a simpler empirical form (eSVB), was derived from basic physical principles that govern blood flow and, in particular, a volume balance approach for the conservation of mass ejected into and flowed out of the arterial system during systole. The formulas were validated by a one-dimensional model of the systemic arterial tree. Comparisons of CO estimates between the proposed and previous methods were performed in terms of agreement and accuracy using “real” CO values of the model as a reference. Five hundred and seven different hemodynamic cases were simulated by altering cardiac period, arterial compliance, and resistance. CO could be accurately estimated by the SVB method as follows: CO = C × PPao/( T − Psm × Ts/Pm) and by the eSVB method as follows: CO = k × C × PPao/ T, where C is arterial compliance, PPao is aortic pulse pressure, T is cardiac period, Psm is mean systolic pressure, Ts is systolic duration, Pm is mean pressure, and k is an empirical coefficient. SVB applied on aortic pressure waves did not require calibration or empirical correction for CO estimation. An empirical coefficient was necessary for brachial pressure wave analysis. The difference of SVB-derived CO from model CO (for brachial waves) was 0.042 ± 0.341 l/min, and the limits of agreement were −0.7 to 0.6 l/min, indicating high accuracy. The intraclass correlation coefficient and root mean square error between estimated and “real” CO were 0.861 and 0.041 l/min, respectively, indicating very good accuracy. eSVB also provided accurate estimation of CO. An in vivo validation study of the proposed methods remains to be conducted.
NADPH oxidase-derived ROS and the regulation of pulmonary vessel tone
Authors: Frazziano G. , Champion H. C. , Pagano P. J.
Published: March 2012

Pulmonary vessel constriction results from an imbalance between vasodilator and vasoconstrictor factors released by the endothelium including nitric oxide, endothelin, prostanoids, and reactive oxygen species (ROS). ROS, generated by a variety of enzymatic sources (such as mitochondria and NADPH oxidases, a.k.a. Nox), appear to play a pivotal role in vascular homeostasis, whereas elevated levels effect vascular disease. The pulmonary circulation is very sensitive to changes in the partial pressure of oxygen and differs from the systemic circulation in its response to this change. In fact, the pulmonary vessels contract in response to low oxygen tension, whereas systemic vessels dilate. Growing evidence suggests that ROS production and ROS-related pathways may be key factors that underlie this differential response to oxygen tension. A major emphasis of our laboratory is the role of Nox isozymes in cardiovascular disease. In this review, we will focus our attention on the role of Nox-derived ROS in the control of pulmonary vascular tone.
Disruption of group IVA cytosolic phospholipase A2attenuates myocardial ischemia-reperfusion injury partly through inhibition of TNF-α-mediated pathway
Authors: Saito Yukio , Watanabe Kazuhiro , Fujioka Daisuke , Nakamura Takamitsu , Obata Jun-ei , Kawabata Kenichi , Watanabe Yosuke , Mishina Hideto , Tamaru Shun , Kita Yoshihiro , Shimizu Takao , Kugiyama Kiyotaka
Published: March 2012

Group IVA cytosolic phospholipase A2(cPLA2α), which preferentially cleaves arachidonic acid from phospholipids, plays a role in apoptosis and tissue injury. Downstream signals in response to tumor necrosis factor (TNF)-α, a mediator of myocardial ischemia-reperfusion (I/R) injury, involve cPLA2α activation. This study examined the potential role of cPLA2α and its mechanistic link with TNF-α in myocardial I/R injury using cPLA2α knockout (cPLA2α−/−) mice. Myocardial I/R was created with 10-wk-old male mice by 1 h ligation of the left anterior descending coronary artery, followed by 24 h of reperfusion. As a result, compared with wild-type (cPLA2α+/+) mice, cPLA2α−/−mice had a 47% decrease in myocardial infarct size, preservation of echocardiographic left ventricle (LV) function (%fractional shortening: 14 vs. 21%, respectively), and lower content of leukotriene B4and thromboxane B2(62 and 50% lower, respectively) in the ischemic myocardium after I/R. Treatment with the TNF-α inhibitor (soluble TNF receptor II/IgG1 Fc fusion protein, sTNFR:Fc) decreased myocardial I/R injury and LV dysfunction in cPLA2α+/+mice but not cPLA2α−/−mice. sTNFR:Fc also suppressed cPLA2α phosphorylation in the ischemic myocardium after I/R of cPLA2α+/+mice. Similarly, sTNFR:Fc exerted protective effects against hypoxia-reoxygenation (H/R)-induced injury in the cultured cardiomyocytes from cPLA2α+/+mice but not cPLA2α−/−cardiomyocytes. H/R and TNF-α induced cPLA2α phosphorylation in cPLA2α+/+cardiomyocytes, which was reversible by sTNFR:Fc. In cPLA2α−/−cardiomyocytes, TNF-α induced apoptosis and release of arachidonic acid to a lesser extent than in cPLA2α+/+cardiomyocytes. In conclusion, disruption of cPLA2α attenuates myocardial I/R injury partly through inhibition of TNF-α-mediated pathways.
The multifunctional Ca2+/calmodulin-dependent kinase II regulates vascular smooth muscle migration through matrix metalloproteinase 9
Authors: Scott Jason A. , Xie Litao , Li Hui , Li Weiwei , He Julie B. , Sanders Philip N. , Carter A. Brent , Backs Johannes , Anderson Mark E. , Grumbach Isabella M.
Published: March 2012

The multifunctional CaMKII has been implicated in vascular smooth muscle cell (VSMC) migration, but little is known regarding its downstream targets that mediate migration. Here, we examined whether CaMKII regulates migration through modulation of matrix metalloproteinase 9 (MMP9). Using CaMKIIδ−/−mice as a model system, we evaluated migration and MMP9 regulation in vitro and in vivo. After ligation of the common carotid artery, CaMKII was activated in the neointima as determined by oxidation and autophosphorylation. We found that MMP9 was robustly expressed in the neointima and adventitia of carotid-ligated wild-type (WT) mice but was barely detectable in CaMKIIδ−/−mice. The perimeter of the external elastic lamina, a correlate of migration-related outward remodeling, was increased in WT but not in CaMKIIδ−/−mice. Migration induced by serum, platelet-derived growth factor, and tumor necrosis factor-α (TNF-α) was significantly decreased in CaMKIIδ−/−as compared with WT VSMCs, but migration was rescued with adenoviral overexpression of MMP9 in CaMKIIδ−/−VSMCs. Likewise, overexpression of CaMKIIδ in CaMKIIδ−/−VSMCs increased migration, whereas an oxidation-resistant mutant of CaMKIIδ did not. TNF-α strongly induced CaMKII oxidation and autophosphorylation as well as MMP9 activity, mRNA, and protein levels in WT, but not in CaMKIIδ−/−VSMC. Surprisingly, TNF-α strongly induced MMP9 promoter activity in WT and CaMKIIδ−/−VSMC. However, the MMP9 mRNA stability was significantly decreased in CaMKIIδ−/−VSMC. Our data demonstrate that CaMKII promotes VSMC migration through posttranscriptional regulation of MMP9 and suggest that CaMKII effects on MMP9 expression may be a therapeutic pathway in vascular injury.
Cardiac mitochondrial network excitability: insights from computational analysis
Authors: Zhou Lufang , O'Rourke Brian
Published: March 2012

In the heart, mitochondria form a regular lattice and function as a coordinated, nonlinear network to continuously produce ATP to meet the high-energy demand of the cardiomyocytes. Cardiac mitochondria also exhibit properties of an excitable system: electrical or chemical signals can spread within or among cells in the syncytium. The detailed mechanisms by which signals pass among individual elements (mitochondria) across the network are still not completely understood, although emerging studies suggest that network excitability might be mediated by the local diffusion and autocatalytic release of messenger molecules such as reactive oxygen species and/or Ca2+. In this short review, we have attempted to described recent advances in the field of cardiac mitochondrial network excitability. Specifically, we have focused on how mitochondria communicate with each other through the diffusion and regeneration of messenger molecules to initiate and propagate waves or oscillations, as revealed by computational models of mitochondrial network.
The p110δ subunit of PI3K regulates bone marrow-derived eosinophil trafficking and airway eosinophilia in allergen-challenged mice
Authors: Kang Bit Na , Ha Sung Gil , Ge Xiao Na , Reza Hosseinkhani M. , Bahaie Nooshin S. , Greenberg Yana , Blumenthal Malcolm N. , Puri Kamal D. , Rao Savita P. , Sriramarao P.
Published: March 2012

Trafficking and recruitment of eosinophils during allergic airway inflammation is mediated by the phosphatidylinositol 3-kinase (PI3K) family of signaling molecules. The role played by the p110δ subunit of PI3K (PI3K p110δ) in regulating eosinophil trafficking and recruitment was investigated using a selective pharmacological inhibitor (IC87114). Treatment with the PI3K p110δ inhibitor significantly reduced murine bone marrow-derived eosinophil (BM-Eos) adhesion to VCAM-1 as well as ICAM-1 and inhibited activation-induced changes in cell morphology associated with reduced Mac-1 expression and aberrant cell surface localization/distribution of Mac-1 and α4. Infused BM-Eos demonstrated significantly decreased rolling and adhesion in inflamed cremaster muscle microvessels of mice treated with IC87114 compared with vehicle-treated mice. Furthermore, inhibition of PI3K p110δ significantly attenuated eotaxin-1-induced BM-Eos migration and prevented eotaxin-1-induced changes in the cytoskeleton and cell morphology. Knockdown of PI3K p110δ with siRNA in BM-Eos resulted in reduced rolling, adhesion, and migration, as well as inhibition of activation-induced changes in cell morphology, validating its role in regulating trafficking and migration. Finally, in a mouse model of cockroach antigen-induced allergic airway inflammation, oral administration of the PI3K p110δ inhibitor significantly inhibited airway eosinophil recruitment, resulting in attenuation of airway hyperresponsiveness in response to methacholine, reduced mucus secretion, and expression of proinflammatory molecules (found in inflammatory zone-1 and intelectin-1). Overall, these findings indicate the important role played by PI3K p110δ in mediating BM-Eos trafficking and migration by regulating adhesion molecule expression and localization/distribution as well as promoting changes in cell morphology that favor recruitment during inflammation.
Prenatal iodine deficiency results in structurally and functionally immature lungs in neonatal rats
Authors: Godbole Madan M. , Rao Geeta , Paul B. N. , Mohan Vishwa , Singh Preeti , Khare Drirh , Babu Satish , Nath Alok , Singh P. K. , Tiwari Swasti
Published: March 2012

Maternal hypothyroidism affects postnatal lung structure. High prevalence of hypothyroxinemia (low T4, normal T3) in iodine-deficient pregnant women and associated risk for neuropsychological development along with high infant/neonatal mortality ascribed to respiratory distress prompted us to study the effects of maternal hypothyroxinemia on postnatal lung development. Female Sprague Dawley rats were given a low-iodine diet (LID) with 1% KClO4in drinking water for 10 days, to minimize thyroid hormone differences. Half of these rats were continued on iodine-deficient diet; ID (LID with 0.005% KClO4) for 3 mo, whereas the rest were switched to an iodine-sufficient diet; IS [LID + potassium iodide (10 μg iodine/20 g of diet + normal drinking water)]. Pups born to ID mothers were compared with age-matched pups from IS mothers at postnatal days 8 (P8) and 16 (P16) ( n = 6–8/group). ID pups had normal circulating T3 but significantly low T4 levels ( P < 0.05) and concomitantly approximately sixfold higher thyroid hormone receptor-β mRNA in alveolar epithelium. Lung histology revealed larger and irregularly shaped alveoli in ID pups relative to controls. Lung function was assessed at P16 using a double-chambered plethysmograph and observed reduced tidal volume, peak inspiratory and expiratory flow, and dynamic lung compliance in ID pups compared with IS pups. Significant lowering of surfactant protein (SP)-B and SP-C mRNA and protein found in ID pups at P16. ID pups had 16-fold lower matrix metalloproteinase-9 mRNA levels in their alveolar epithelium. In addition, mRNA levels of thyroid transcription factor-1 and SP-D were significantly higher (3-fold) compared with IS pups. At P16, significantly lower levels of SP-B and SP-C found in ID pups may be responsible for immature lung development and reduced lung compliance. Our data suggest that maternal hypothyroxinemia may result in the development of immature lungs that, through respiratory distress, could contribute to the observed high infant mortality in ID neonates.
Dual-energy micro-CT of the rodent lung
Authors: Badea C. T. , Guo X. , Clark D. , Johnston S. M. , Marshall C. D. , Piantadosi C. A.
Published: March 2012

The purpose of this work is to investigate the use of dual-energy micro-computed tomography (CT) for the estimation of vascular, tissue, and air fractions in rodent lungs using a postreconstruction three material decomposition method. Using simulations, we have estimated the accuracy limits of the decomposition for realistic micro-CT noise levels. Next, we performed experiments involving ex vivo lung imaging in which intact rat lungs were carefully removed from the thorax, injected with an iodine-based contrast agent, and then inflated with different volumes of air ( n = 2). Finally, we performed in vivo imaging studies in C57BL/6 mice ( n = 5) using fast prospective respiratory gating in end inspiration and end expiration for three different levels of positive end expiratory pressure (PEEP). Before imaging, mice were injected with a liposomal blood pool contrast agent. The three-dimensional air, tissue, and blood fraction maps were computed and analyzed. The results indicate that separation and volume estimation of the three material components of the lungs are possible. The mean accuracy values for air, blood, and tissue were 93, 93, and 90%, respectively. The absolute accuracy in determining all fraction materials was 91.6%. The coefficient of variation was small (2.5%) indicating good repeatability. The minimum difference that we could detect in material fractions was 15%. As expected, an increase in PEEP levels for the living mouse resulted in statistically significant increases in air fractions at end expiration but no significant changes at end inspiration. Our method has applicability in preclinical pulmonary studies where changes in lung structure and gas volume as a result of lung injury, environmental exposures, or drug bioactivity would have important physiological implications.
Nerve growth factor modulates human rhinovirus infection in airway epithelial cells by controlling ICAM-1 expression
Authors: Othumpangat Sreekumar , Regier Michael , Piedimonte Giovanni
Published: March 2012

Human rhinoviruses (HRV) are the most common agent of upper respiratory infections and an important cause of lower respiratory tract symptoms. Our previous research with other viral pathogens has shown that virus-induced airway inflammation and hyperreactivity involve neurotrophic pathways that also affect tropism and severity of the infection. The goals of this study were to analyze systematically the expression of key neurotrophic factors and receptors during HRV-16 infection of human airway epithelial cells and to test the hypothesis that neurotrophins modulate HRV infection by controlling the expression of a major cellular receptor for this virus, the intercellular adhesion molecule 1 (ICAM-1). Neurotrophins and ICAM-1 expression were analyzed at the mRNA level by real-time PCR and at the protein level by flow cytometry and immunocytochemistry. A small inhibitory RNA (siRNA) or a specific blocking antibody was utilized to suppress nerve growth factor (NGF) expression and measure its effects on viral replication and virus-induced cell death. Nasal and bronchial epithelial cells were most susceptible to HRV-16 infection at 33°C and 37°C, respectively, and a significant positive relationship was noted between expression of NGF and tropomyosin-related kinase A (TrkA) and virus copy number. ICAM-1 expression was dose dependently upregulated by exogenous NGF and significantly downregulated by NGF inhibition with corresponding decrease in HRV-16 replication. NGF inhibition also increased apoptotic death of infected cells. Our results suggest that HRV upregulates the NGF-TrkA pathway in airway epithelial cells, which in turn amplifies viral replication by increasing HRV entry via ICAM-1 receptors and by limiting apoptosis.