Effects of process parameters on the molding quality of the micro-needle array

NASA Astrophysics Data System (ADS)

Qiu, Z. J.; Ma, Z.; Gao, S.

2016-07-01

Micro-needle array, which is used in medical applications, is a kind of typical injection molded products with microstructures. Due to its tiny micro-features size and high aspect ratios, it is more likely to produce short shots defects, leading to poor molding quality. The injection molding process of the micro-needle array was studied in this paper to find the effects of the process parameters on the molding quality of the micro-needle array and to provide theoretical guidance for practical production of high-quality products. With the shrinkage ratio and warpage of micro needles as the evaluation indices of the molding quality, the orthogonal experiment was conducted and the analysis of variance was carried out. According to the results, the contribution rates were calculated to determine the influence of various process parameters on molding quality. The single parameter method was used to analyse the main process parameter. It was found that the contribution rate of the holding pressure on shrinkage ratio and warpage reached 83.55% and 94.71% respectively, far higher than that of the other parameters. The study revealed that the holding pressure is the main factor which affects the molding quality of micro-needle array so that it should be focused on in order to obtain plastic parts with high quality in the practical production.

Oligonucleotide-arrayed TFT photosensor applicable for DNA chip technology.

PubMed

Tanaka, Tsuyoshi; Hatakeyama, Keiichi; Sawaguchi, Masahiro; Iwadate, Akihito; Mizutani, Yasushi; Sasaki, Kazuhiro; Tateishi, Naofumi; Takeyama, Haruko; Matsunaga, Tadashi

2006-09-05

A thin film transistor (TFT) photosensor fabricated by semiconductor integrated circuit (IC) technology was applied to DNA chip technology. The surface of the TFT photosensor was coated with TiO2 using a vapor deposition technique for the fabrication of optical filters. The immobilization of thiolated oligonucleotide probes onto a TiO2-coated TFT photosensor using gamma-aminopropyltriethoxysilane (APTES) and N-(gamma-maleimidobutyloxy) sulfosuccinimide ester (GMBS) was optimized. The coverage value of immobilized oligonucleotides reached a plateau at 33.7 pmol/cm2, which was similar to a previous analysis using radioisotope-labeled oligonucleotides. The lowest detection limits were 0.05 pmol/cm2 for quantum dot and 2.1 pmol/cm2 for Alexa Fluor 350. Furthermore, single nucleotide polymorphism (SNP) detection was examined using the oligonucleotide-arrayed TFT photosensor. A SNP present in the aldehyde dehydrogenase 2 (ALDH2) gene was used as a target. The SNPs in ALDH2*1 and ALDH2*2 target DNA were detected successfully using the TFT photosensor. DNA hybridization in the presence of both ALDH2*1 and ALDH2*2 target DNA was observed using both ALDH2*1 and ALDH2*2 detection oligonucleotides-arrayed TFT photosensor. Use of the TFT photosensor will allow the development of a disposable photodetecting device for DNA chip systems. (c) 2006 Wiley Periodicals, Inc.

Review on thin-film transistor technology, its applications, and possible new applications to biological cells

NASA Astrophysics Data System (ADS)

Tixier-Mita, Agnès; Ihida, Satoshi; Ségard, Bertrand-David; Cathcart, Grant A.; Takahashi, Takuya; Fujita, Hiroyuki; Toshiyoshi, Hiroshi

2016-04-01

This paper presents a review on state-of-the-art of thin-film transistor (TFT) technology and its wide range of applications, not only in liquid crystal displays (TFT-LCDs), but also in sensing devices. The history of the evolution of the technology is first given. Then the standard applications of TFT-LCDs, and X-ray detectors, followed by state-of-the-art applications in the field of chemical and biochemical sensing are presented. TFT technology allows the fabrication of dense arrays of independent and transparent microelectrodes on large glass substrates. The potential of these devices as electrical substrates for biological cell applications is then described. The possibility of using TFT array substrates as new tools for electrical experiments on biological cells has been investigated for the first time by our group. Dielectrophoresis experiments and impedance measurements on yeast cells are presented here. Their promising results open the door towards new applications of TFT technology.

CdSe TFT AMLCDE manufacturing process

NASA Astrophysics Data System (ADS)

Pritchard, Annette M.

1995-06-01

Active Matrix Liquid Crystal Displays, AMLCDs, based on Cadmium Selenide Thin Film Transistors, have been developed by Litton for a number of defence/avionics applications. Fabrication processed for the thin film transistor (TFT) arrays, color filters and liquid crystal cell assembly have been developed which enable the end product to meet the difficult environmental and performance specifications of military applications, while maintaining focus on cost and yield issues. The fabrication of the AMLCD products is now transitioning into a new production facility which has been designed specifically to meet the requirements of the defence/avionics marketplace.

Mercuric iodide medical imagers for low-exposure radiography and fluoroscopy

NASA Astrophysics Data System (ADS)

Zentai, George; Partain, Larry; Pavlyuchkova, Raisa; Proano, Cesar; Breen, Barry N.; Taieb, A.; Dagan, Ofer; Schieber, Michael; Gilboa, Haim; Thomas, Jerry

2004-05-01

Photoconductive polycrystalline mercuric iodide deposited on flat panel thin film transistor (TFT) arrays is being developed for direct digital X-ray detectors that can perform both radiographic and fluoroscopic medical imaging. The mercuric iodide is either vacuum deposited by Physical Vapor Deposition (PVD) or coated onto the array by a wet Particle-In-Binder (PIB) process. The PVD deposition technology has been scaled up to the 20 cm x 25 cm size required in common medical imaging applications. A TFT array with a pixel pitch of 127 microns is used for these imagers. Arrays of 10 cm x 10 cm size have been used to evaluate performance of mercuric iodide imagers. Radiographic and fluoroscopic images of diagnostic quality at up to 15 pulses per second were demonstrated. As we previously reported, the resolution is limited to the TFT array Nyquist frequency of ~3.9 lp/mm (127 micron pixel pitch). Detective Quantum Efficiency (DQE) has been measured as a function of spatial frequency for these imagers. The DQE is lower than the theoretically calculated value due to some additional noise sources of the electronics and the array. We will retest the DQE after eliminating these noise sources. Reliability and stress testing was also began for polycrystalline mercuric iodide PVD and PIB detectors. These are simplified detectors based upon a stripe electrode or circular electrode structure. The detectors were stressed under various voltage bias, temperature and time conditions. The effects of the stress tests on the detector dark current and sensitivity were determined.

Method of fabrication of display pixels driven by silicon thin film transistors

DOEpatents

Carey, Paul G.; Smith, Patrick M.

1999-01-01

Display pixels driven by silicon thin film transistors are fabricated on plastic substrates for use in active matrix displays, such as flat panel displays. The process for forming the pixels involves a prior method for forming individual silicon thin film transistors on low-temperature plastic substrates. Low-temperature substrates are generally considered as being incapable of withstanding sustained processing temperatures greater than about 200.degree. C. The pixel formation process results in a complete pixel and active matrix pixel array. A pixel (or picture element) in an active matrix display consists of a silicon thin film transistor (TFT) and a large electrode, which may control a liquid crystal light valve, an emissive material (such as a light emitting diode or LED), or some other light emitting or attenuating material. The pixels can be connected in arrays wherein rows of pixels contain common gate electrodes and columns of pixels contain common drain electrodes. The source electrode of each pixel TFT is connected to its pixel electrode, and is electrically isolated from every other circuit element in the pixel array.

Toward active-matrix lab-on-a-chip: programmable electrofluidic control enabled by arrayed oxide thin film transistors.

PubMed

Noh, Joo Hyon; Noh, Jiyong; Kreit, Eric; Heikenfeld, Jason; Rack, Philip D

2012-01-21

Agile micro- and nano-fluidic control is critical to numerous life science and chemical science synthesis as well as kinetic and thermodynamic studies. To this end, we have demonstrated the use of thin film transistor arrays as an active matrix addressing method to control an electrofluidic array. Because the active matrix method minimizes the number of control lines necessary (m + n lines for the m×n element array), the active matrix addressing method integrated with an electrofluidic platform can be a significant breakthrough for complex electrofluidic arrays (increased size or resolution) with enhanced function, agility and programmability. An amorphous indium gallium zinc oxide (a-IGZO) semiconductor active layer is used because of its high mobility of 1-15 cm(2) V(-1) s(-1), low-temperature processing and transparency for potential spectroscopy and imaging. Several electrofluidic functionalities are demonstrated using a simple 2 × 5 electrode array connected to a 2 × 5 IGZO thin film transistor array with the semiconductor channel width of 50 μm and mobility of 6.3 cm(2) V(-1) s(-1). Additionally, using the TFT device characteristics, active matrix addressing schemes are discussed as the geometry of the electrode array can be tailored to act as a storage capacitor element. Finally, requisite material and device parameters are discussed in context with a VGA scale active matrix addressed electrofluidic platform.

Defect Analysis of Roll-to-Roll SAIL Manufactured Flexible Display Backplanes

DTIC Science & Technology

2011-01-01

tenting defect through the SAIL process Figure 5: Flexible backplane electrical tester Figure 6: R2R optical inspection system Figure 7: TEM of TFT ...Analysis of Roll-to-Roll SAIL Manufactured Flexible Display...Marcia Almanza-Workman, Robert A. Garcia, HanJun Kim, Ohseung Kwon, Frank Jeffrey HP Laboratories HPL-2011-35 SAIL, flexible displays, roll-to-roll HP

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Po-Tsun, E-mail: ptliu@mail.nctu.edu.tw; Chang, Chih-Hsiang; Chang, Chih-Jui

This study investigates the instability induced by bias temperature illumination stress (NBTIS) for an amorphous indium-tungsten-oxide thin film transistor (a-IWO TFT) with SiO{sub 2} backchannel passivation layer (BPL). It is found that this electrical degradation phenomenon can be attributed to the generation of defect states during the BPL process, which deteriorates the photo-bias stability of a-IWO TFTs. A method proposed by adding an oxygen-rich a-IWO thin film upon the a-IWO active channel layer could effectively suppress the plasma damage to channel layer during BPL deposition process. The bi-layer a-IWO TFT structure with an oxygen-rich back channel exhibits superior electrical reliabilitymore » of device under NBTIS.« less

Pentacene-based organic thin film transistors, integrated circuits, and active matrix displays on polymeric substrates

NASA Astrophysics Data System (ADS)

Sheraw, Christopher Duncan

2003-10-01

Organic thin film transistors are attractive candidates for a variety of low cost, large area commercial electronics including smart cards, RF identification tags, and flat panel displays. Of particular interest are high performance organic thin film transistors (TFTs) that can be fabricated on flexible polymeric substrates allowing low-cost, lightweight, rugged electronics such as flexible active matrix displays. This thesis reports pentacene organic thin film transistors fabricated on flexible polymeric substrates with record performance, the fastest photolithographically patterned organic TFT integrated circuits on polymeric substrates reported to date, and the fabrication of the organic TFT backplanes used to build the first organic TFT-driven active matrix liquid crystal display (AMLCD), also the first AMLCD on a flexible substrate, ever reported. In addition, the first investigation of functionalized pentacene derivatives used as the active layer in organic thin film transistors is reported. A low temperature (<110°C) process technology was developed allowing the fabrication of high performance organic TFTs, integrated circuits, and large TFT arrays on flexible polymeric substrates. This process includes the development of a novel water-based photolithographic active layer patterning process using polyvinyl alcohol that allows the patterning of organic semiconductor materials for elimination of active layer leakage current without causing device degradation. The small molecule aromatic hydrocarbon pentacene was used as the active layer material to fabricate organic TFTs on the polymeric material polyethylene naphthalate with field-effect mobility as large as 2.1 cm2/V-s and on/off current ratio of 108. These are the best values reported for organic TFTs on polymeric substrates and comparable to organic TFTs on rigid substrates. Analog and digital integrated circuits were also fabricated on polymeric substrates using pentacene TFTs with propagation delay as low as 38 musec and clocked digital circuits that operated at 1.1 kHz. These are the fastest photolithographically patterned organic TFT circuits on polymeric substrates reported to date. Finally, 16 x 16 pentacene TFT pixel arrays were fabricated on polymeric substrates and integrated with polymer dispersed liquid crystal to build an AMLCD. The pixel arrays showed good optical response to changing data signals when standard quarter-VGA display waveforms were applied. This result marks the first organic TFT-driven active matrix liquid crystal display ever reported as well as the first active matrix liquid crystal display on a flexible polymeric substrate. Lastly, functionalized pentacene derivatives were used as the active layer in organic thin film transistor materials. Functional groups were added to the pentacene molecule to influence the molecular ordering so that the amount of pi-orbital overlap would be increased allowing the potential for improved field-effect mobility. The functionalization of these materials also improves solubility allowing for the possibility of solution-processed devices and increased oxidative stability. Organic thin film transistors were fabricated using five different functionalized pentacene active layers. Devices based on the pentacene derivative triisopropylsilyl pentacene were found to have the best performance with field-effect mobility as large as 0.4 cm 2/V-s.

Very low temperature materials and self-alignment technology for amorphous hydrated silicon thin film transistors fabricated on transparent large area plastic substrates

NASA Astrophysics Data System (ADS)

Yang, Chien-Sheng

The purpose of this research has been to (1) explore materials prepared using plasma enhanced chemical vapor deposition (PECVD) at 110sp°C for amorphous silicon thin film transistors (TFT's) fabricated on low temperature compatible, large area flexible polyethylene terephthalate (PET) substrates, and (2) develop full self-alignment technology using selective area n+ PECVD for source/drain contacts of amorphous silicon TFT's. For item (1), silicon nitride films, as gate dielectrics of TFT's, were deposited using SiHsb4+NHsb3, SiHsb4+NHsb3+Nsb2, SiHsb4+NHsb3+He, or SiHsb4+NHsb3+Hsb2 gases. Good quality silicon nitride films can be deposited using a SiHsb4+NHsb3 gas with high NHsb3/SiHsb4 ratios, or using a SiHsb4+NHsb3+Nsb2 gas with moderate NHsb3/SiHsb4 ratios. A chemical model was proposed to explain the Nsb2 dilution effect. This model includes calculations of (a) the electron energy distribution function in a plasma, (b) rate constants of electron impact dissociation, and (3) the (NHsbx) / (SiHsby) ratio in a plasma. The Nsb2 dilution was shown to have a effect of shifting the electron energy distribution into high energy, thus enhancing the (NHsbx) / (SiHsbyrbrack ratio in a plasma and promoting the deposition of N-rich silicon nitride films, which leads to decreased trap state density and a shift in trap state density to deeper in the gap. Amorphous silicon were formed successfully at 110sp°C on large area glass and plastic(PET) substrates. Linear mobilities are 0.33 and 0.12 cmsp2/Vs for TFT's on glass and plastic substrates, respectively. ON/OFF current ratios exceed 10sp7 for TFT's on glass and 10sp6 for TFT's on PET. For item (2), a novel full self-alignment process was developed for amorphous silicon TFT's. This process includes (1) back-exposure using the bottom gate metal as the mask, and (2) selective area n+ micro-crystalline silicon PECVD for source/drain contacts of amorphous silicon TFT's. TFT's fabricated using the full self-alignment process showed linear mobilities ranging from 0.5 to 1.0 cmsp2/Vs.

Wireless thin film transistor based on micro magnetic induction coupling antenna.

PubMed

Jun, Byoung Ok; Lee, Gwang Jun; Kang, Jong Gu; Kim, Seunguk; Choi, Ji-Woong; Cha, Seung Nam; Sohn, Jung Inn; Jang, Jae Eun

2015-12-22

A wireless thin film transistor (TFT) structure in which a source/drain or a gate is connected directly to a micro antenna to receive or transmit signals or power can be an important building block, acting as an electrical switch, a rectifier or an amplifier, for various electronics as well as microelectronics, since it allows simple connection with other devices, unlike conventional wire connections. An amorphous indium gallium zinc oxide (α-IGZO) TFT with magnetic antenna structure was fabricated and studied for this purpose. To enhance the induction coupling efficiency while maintaining the same small antenna size, a magnetic core structure consisting of Ni and nanowires was formed under the antenna. With the micro-antenna connected to a source/drain or a gate of the TFT, working electrical signals were well controlled. The results demonstrated the device as an alternative solution to existing wire connections which cause a number of problems in various fields such as flexible/wearable devices, body implanted devices, micro/nano robots, and sensors for the 'internet of things' (IoT).

Wireless thin film transistor based on micro magnetic induction coupling antenna

PubMed Central

Jun, Byoung Ok; Lee, Gwang Jun; Kang, Jong Gu; Kim, Seunguk; Choi, Ji-Woong; Cha, Seung Nam; Sohn, Jung Inn; Jang, Jae Eun

2015-01-01

A wireless thin film transistor (TFT) structure in which a source/drain or a gate is connected directly to a micro antenna to receive or transmit signals or power can be an important building block, acting as an electrical switch, a rectifier or an amplifier, for various electronics as well as microelectronics, since it allows simple connection with other devices, unlike conventional wire connections. An amorphous indium gallium zinc oxide (α-IGZO) TFT with magnetic antenna structure was fabricated and studied for this purpose. To enhance the induction coupling efficiency while maintaining the same small antenna size, a magnetic core structure consisting of Ni and nanowires was formed under the antenna. With the micro-antenna connected to a source/drain or a gate of the TFT, working electrical signals were well controlled. The results demonstrated the device as an alternative solution to existing wire connections which cause a number of problems in various fields such as flexible/wearable devices, body implanted devices, micro/nano robots, and sensors for the ‘internet of things’ (IoT). PMID:26691929

Wireless thin film transistor based on micro magnetic induction coupling antenna

NASA Astrophysics Data System (ADS)

Jun, Byoung Ok; Lee, Gwang Jun; Kang, Jong Gu; Kim, Seunguk; Choi, Ji-Woong; Cha, Seung Nam; Sohn, Jung Inn; Jang, Jae Eun

2015-12-01

A wireless thin film transistor (TFT) structure in which a source/drain or a gate is connected directly to a micro antenna to receive or transmit signals or power can be an important building block, acting as an electrical switch, a rectifier or an amplifier, for various electronics as well as microelectronics, since it allows simple connection with other devices, unlike conventional wire connections. An amorphous indium gallium zinc oxide (α-IGZO) TFT with magnetic antenna structure was fabricated and studied for this purpose. To enhance the induction coupling efficiency while maintaining the same small antenna size, a magnetic core structure consisting of Ni and nanowires was formed under the antenna. With the micro-antenna connected to a source/drain or a gate of the TFT, working electrical signals were well controlled. The results demonstrated the device as an alternative solution to existing wire connections which cause a number of problems in various fields such as flexible/wearable devices, body implanted devices, micro/nano robots, and sensors for the ‘internet of things’ (IoT).

Combination with anti-tit-for-tat remedies problems of tit-for-tat.

PubMed

Yi, Su Do; Baek, Seung Ki; Choi, Jung-Kyoo

2017-01-07

One of the most important questions in game theory concerns how mutual cooperation can be achieved and maintained in a social dilemma. In Axelrod's tournaments of the iterated prisoner's dilemma, Tit-for-Tat (TFT) demonstrated the role of reciprocity in the emergence of cooperation. However, the stability of TFT does not hold in the presence of implementation error, and a TFT population is prone to neutral drift to unconditional cooperation, which eventually invites defectors. We argue that a combination of TFT and anti-TFT (ATFT) overcomes these difficulties in a noisy environment, provided that ATFT is defined as choosing the opposite to the opponent's last move. According to this TFT-ATFT strategy, a player normally uses TFT; turns to ATFT upon recognizing his or her own error; returns to TFT either when mutual cooperation is recovered or when the opponent unilaterally defects twice in a row. The proposed strategy provides simple and deterministic behavioral rules for correcting implementation error in a way that cannot be exploited by the opponent, and suppresses the neutral drift to unconditional cooperation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Multi-oxide active layer deposition using Applied Materials Pivot array coater for high-mobility metal oxide TFT

NASA Astrophysics Data System (ADS)

Park, Hyun Chan; Scheer, Evelyn; Witting, Karin; Hanika, Markus; Bender, Marcus; Hsu, Hao Chien; Yim, Dong Kil

2015-11-01

By controlling a thin indium tin oxide (ITO), indium zinc oxide interface layer between gate insulator and indium gallium zinc oxide (IGZO), the thin-film transistor (TFT) performance can reach higher mobility as conventional IGZO as well as superior stability. For large-area display application, Applied Materials static PVD array coater (Applied Materials GmbH & Co. KG, Alzenau, Germany) using rotary targets has been developed to enable uniform thin layer deposition in display industry. Unique magnet motion parameter optimization in Pivot sputtering coater is shown to provide very uniform thin ITO layer to reach TFT performance with high mobility, not only on small scale, but also on Gen8.5 (2500 × 2200 mm glass size) production system.

How Suspicion Grows: Effects of Population Size on Cooperation

DTIC Science & Technology

2014-09-01

suspicious tit-for-tat TFT tit-for-tat TF2T tit-for-two-tats xiii THIS PAGE INTENTIONALLY LEFT BLANK xiv Executive Summary People in a group typically...theoretic model mathematically tractable, we restrict each individual to four strategies: tit-for-two-tats (TF2T), tit-for-tat ( TFT ), suspicious-tit...stranger, TF2T will begin by cooperation twice, TFT by cooperating once, and STFT by defecting once. After the initial moves, in each encounter, the

Experimental analysis for fabrication of high-aspect-ratio piezoelectric ceramic structure by micro-powder injection molding process

NASA Astrophysics Data System (ADS)

Han, Jun Sae; Gal, Chang Woo; Park, Jae Man; Kim, Jong Hyun; Park, Seong Jin

2018-04-01

Aspect ratio effects in the micro-powder injection molding process were experimentally analyzed for fabrication of high-aspect-ratio piezoelectric ceramic structure. The mechanisms of critical defects have been studied according to individual manufacturing steps. In the molding process, incomplete filling phenomenon determines the critical aspect ratios of a micro pattern. According to mold temperature, an incomplete filling phenomenon has been analyzed with respect to different pattern sizes and aspect ratio. In demolding and drying process, the capillary behavior of sacrificial polymeric mold insert determines the critical aspect ratio of a micro pattern. With respect to pattern dimensions, slumping behavior has been analyzed. Based on our current systems, micro PZT feature has stability when it has lower aspect ratio than 5. Under optimized processing conditions, 20 μm and 40 μm ceramic rod array feature which has 5 of aspect ratio were successfully fabricated by the developed process. Further modification points to fabricate the smaller and higher feature were specifically addressed.

Combined membrane bioreactor (MBR) and reverse osmosis (RO) system for thin-film transistor-liquid crystal display TFT-LCD, industrial wastewater recycling.

PubMed

Chen, T K; Chen, J N

2004-01-01

In TFT-LCD industry, water plays a variety of roles as a cleaning agent and reaction solvent. As good quality water is increasingly a scarce resource and wastewater treatment costs rises, the once-through use of industrial water is becoming uneconomical and environmentally unacceptable. Instead, recycling of TFT-LCD industrial wastewater is become more attractive from both an economic and environmental perspective. This research is mainly to explore the capacity of TFT-LCD industrial wastewater recycling by the process combined with membrane bioreactor and reverse osmosis processes. Over the whole experimental period, the MBR process achieved a satisfactory organic removal. The COD could be removed with an average of over 97.3%. For TOC and BOD5 items, the average removal efficiencies were 97.8 and 99.4% respectively. The stable effluent quality and satisfactory removal performance were ensured by the efficient interception performance of the UF membrane device incorporated with biological reactor. Moreover, the MBR effluent did not contain any suspended solids and the SDI value was under 3. After treatment of RO, excellent water quality of permeate were under 5 mg/l, 2.5 mg/l and 150 micros/cm for COD, TOC and conductivity respectively. The treated water can be recycled for the cooling tower make-up water or other purposes.

Defect reduction in overgrown semi-polar (11-22) GaN on a regularly arrayed micro-rod array template

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Y.; Bai, J.; Hou, Y.

2016-02-15

We demonstrate a great improvement in the crystal quality of our semi-polar (11-22) GaN overgrown on regularly arrayed micro-rod templates fabricated using a combination of industry-matched photolithography and dry-etching techniques. As a result of our micro-rod configuration specially designed, an intrinsic issue on the anisotropic growth rate which is a great challenge in conventional overgrowth technique for semi-polar GaN has been resolved. Transmission electron microscopy measurements show a different mechanism of defect reduction from conventional overgrowth techniques and also demonstrate major advantages of our approach. The dislocations existing in the GaN micro-rods are effectively blocked by both a SiO{sub 2}more » mask on the top of each GaN micro-rod and lateral growth along the c-direction, where the growth rate along the c-direction is faster than that along any other direction. Basal stacking faults (BSFs) are also effectively impeded, leading to a distribution of BSF-free regions periodically spaced by BSF regions along the [-1-123] direction, in which high and low BSF density areas further show a periodic distribution along the [1-100] direction. Furthermore, a defect reduction model is proposed for further improvement in the crystalline quality of overgrown (11-22) GaN on sapphire.« less

A cascade method for TFT-LCD defect detection

NASA Astrophysics Data System (ADS)

Yi, Songsong; Wu, Xiaojun; Yu, Zhiyang; Mo, Zhuoya

2017-07-01

In this paper, we propose a novel cascade detection algorithm which focuses on point and line defects on TFT-LCD. At the first step of the algorithm, we use the gray level difference of su-bimage to segment the abnormal area. The second step is based on phase only transform (POT) which corresponds to the Discrete Fourier Transform (DFT), normalized by the magnitude. It can remove regularities like texture and noise. After that, we improve the method of setting regions of interest (ROI) with the method of edge segmentation and polar transformation. The algorithm has outstanding performance in both computation speed and accuracy. It can solve most of the defect detections including dark point, light point, dark line, etc.

Assessment of Manual Operation Time for the Manufacturing of Thin Film Transistor Liquid Crystal Display: A Bayesian Approach

NASA Astrophysics Data System (ADS)

Shen, Chien-wen

2009-01-01

During the processes of TFT-LCD manufacturing, steps like visual inspection of panel surface defects still heavily rely on manual operations. As the manual inspection time of TFT-LCD manufacturing could range from 4 hours to 1 day, the reliability of time forecasting is thus important for production planning, scheduling and customer response. This study would like to propose a practical and easy-to-implement prediction model through the approach of Bayesian networks for time estimation of manual operated procedures in TFT-LCD manufacturing. Given the lack of prior knowledge about manual operation time, algorithms of necessary path condition and expectation-maximization are used for structural learning and estimation of conditional probability distributions respectively. This study also applied Bayesian inference to evaluate the relationships between explanatory variables and manual operation time. With the empirical applications of this proposed forecasting model, approach of Bayesian networks demonstrates its practicability and prediction accountability.

Design, optimization and evaluation of a "smart" pixel sensor array for low-dose digital radiography

NASA Astrophysics Data System (ADS)

Wang, Kai; Liu, Xinghui; Ou, Hai; Chen, Jun

2016-04-01

Amorphous silicon (a-Si:H) thin-film transistors (TFTs) have been widely used to build flat-panel X-ray detectors for digital radiography (DR). As the demand for low-dose X-ray imaging grows, a detector with high signal-to-noise-ratio (SNR) pixel architecture emerges. "Smart" pixel is intended to use a dual-gate photosensitive TFT for sensing, storage, and switch. It differs from a conventional passive pixel sensor (PPS) and active pixel sensor (APS) in that all these three functions are combined into one device instead of three separate units in a pixel. Thus, it is expected to have high fill factor and high spatial resolution. In addition, it utilizes the amplification effect of the dual-gate photosensitive TFT to form a one-transistor APS that leads to a potentially high SNR. This paper addresses the design, optimization and evaluation of the smart pixel sensor and array for low-dose DR. We will design and optimize the smart pixel from the scintillator to TFT levels and validate it through optical and electrical simulation and experiments of a 4x4 sensor array.

Achieving high field-effect mobility in amorphous indium-gallium-zinc oxide by capping a strong reduction layer.

PubMed

Zan, Hsiao-Wen; Yeh, Chun-Cheng; Meng, Hsin-Fei; Tsai, Chuang-Chuang; Chen, Liang-Hao

2012-07-10

An effective approach to reduce defects and increase electron mobility in a-IGZO thin-film transistors (a-IGZO TFTs) is introduced. A strong reduction layer, calcium, is capped onto the back interface of a-IGZO TFT. After calcium capping, the effective electron mobility of a-IGZO TFT increases from 12 cm(2) V(-1) s(-1) to 160 cm(2) V(-1) s(-1). This high mobility is a new record, which implies that the proposed defect reduction effect is key to improve electron transport in oxide semiconductor materials. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pixel electronic noise as a function of position in an active matrix flat panel imaging array

NASA Astrophysics Data System (ADS)

Yazdandoost, Mohammad Y.; Wu, Dali; Karim, Karim S.

2010-04-01

We present an analysis of output referred pixel electronic noise as a function of position in the active matrix array for both active and passive pixel architectures. Three different noise sources for Active Pixel Sensor (APS) arrays are considered: readout period noise, reset period noise and leakage current noise of the reset TFT during readout. For the state-of-the-art Passive Pixel Sensor (PPS) array, the readout noise of the TFT switch is considered. Measured noise results are obtained by modeling the array connections with RC ladders on a small in-house fabricated prototype. The results indicate that the pixels in the rows located in the middle part of the array have less random electronic noise at the output of the off-panel charge amplifier compared to the ones in rows at the two edges of the array. These results can help optimize for clearer images as well as help define the region-of-interest with the best signal-to-noise ratio in an active matrix digital flat panel imaging array.

Theoretical investigation of the noise performance of active pixel imaging arrays based on polycrystalline silicon thin film transistors.

PubMed

Koniczek, Martin; Antonuk, Larry E; El-Mohri, Youcef; Liang, Albert K; Zhao, Qihua

2017-07-01

Active matrix flat-panel imagers, which typically incorporate a pixelated array with one a-Si:H thin-film transistor (TFT) per pixel, have become ubiquitous by virtue of many advantages, including large monolithic construction, radiation tolerance, and high DQE. However, at low exposures such as those encountered in fluoroscopy, digital breast tomosynthesis and breast computed tomography, DQE is degraded due to the modest average signal generated per interacting x-ray relative to electronic additive noise levels of ~1000 e, or greater. A promising strategy for overcoming this limitation is to introduce an amplifier into each pixel, referred to as the active pixel (AP) concept. Such circuits provide in-pixel amplification prior to readout as well as facilitate correlated multiple sampling, enhancing signal-to-noise and restoring DQE at low exposures. In this study, a methodology for theoretically investigating the signal and noise performance of imaging array designs is introduced and applied to the case of AP circuits based on low-temperature polycrystalline silicon (poly-Si), a semiconductor suited to manufacture of large area, radiation tolerant arrays. Computer simulations employing an analog circuit simulator and performed in the temporal domain were used to investigate signal characteristics and major sources of electronic additive noise for various pixel amplifier designs. The noise sources include photodiode shot noise and resistor thermal noise, as well as TFT thermal and flicker noise. TFT signal behavior and flicker noise were parameterized from fits to measurements performed on individual poly-Si test TFTs. The performance of three single-stage and three two-stage pixel amplifier designs were investigated under conditions relevant to fluoroscopy. The study assumes a 20 × 20 cm 2 , 150 μm pitch array operated at 30 fps and coupled to a CsI:Tl x-ray converter. Noise simulations were performed as a function of operating conditions, including sampling mode, of the designs. The total electronic additive noise included noise contributions from each circuit component. The total noise results were found to exhibit a strong dependence on circuit design and operating conditions, with TFT flicker noise generally found to be the dominant noise contributor. For the single-stage designs, significantly increasing the size of the source-follower TFT substantially reduced flicker noise - with the lowest total noise found to be ~574 e [rms]. For the two-stage designs, in addition to tuning TFT sizes and introducing a low-pass filter, replacing a p-type TFT with a resistor (under the assumption in the study that resistors make no flicker noise contribution) resulted in significant noise reduction - with the lowest total noise found to be ~336 e [rms]. A methodology based on circuit simulations which facilitates comprehensive explorations of signal and noise characteristics has been developed and applied to the case of poly-Si AP arrays. The encouraging results suggest that the electronic additive noise of such devices can be substantially reduced through judicious circuit design, signal amplification, and multiple sampling. This methodology could be extended to explore the noise performance of arrays employing other pixel circuitry such as that for photon counting as well as other semiconductor materials such as a-Si:H and a-IGZO. © 2017 American Association of Physicists in Medicine.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scheuermann, James R., E-mail: James.Scheuermann@stonybrook.edu; Goldan, Amir H.; Zhao, Wei

Purpose: Active matrix flat panel imagers (AMFPI) have limited performance in low dose applications due to the electronic noise of the thin film transistor (TFT) array. A uniform layer of avalanche amorphous selenium (a-Se) called high gain avalanche rushing photoconductor (HARP) allows for signal amplification prior to readout from the TFT array, largely eliminating the effects of the electronic noise. The authors report preliminary avalanche gain measurements from the first HARP structure developed for direct deposition onto a TFT array. Methods: The HARP structure is fabricated on a glass substrate in the form of p-i-n, i.e., the electron blocking layermore » (p) followed by an intrinsic (i) a-Se layer and finally the hole blocking layer (n). All deposition procedures are scalable to large area detectors. Integrated charge is measured from pulsed optical excitation incident on the top electrode (as would in an indirect AMFPI) under continuous high voltage bias. Avalanche gain measurements were obtained from samples fabricated simultaneously at different locations in the evaporator to evaluate performance uniformity across large area. Results: An avalanche gain of up to 80 was obtained, which showed field dependence consistent with previous measurements from n-i-p HARP structures established for vacuum tubes. Measurements from multiple samples demonstrate the spatial uniformity of performance using large area deposition methods. Finally, the results were highly reproducible during the time course of the entire study. Conclusions: We present promising avalanche gain measurement results from a novel HARP structure that can be deposited onto a TFT array. This is a crucial step toward the practical feasibility of AMFPI with avalanche gain, enabling quantum noise limited performance down to a single x-ray photon per pixel.« less

Development of solid-state avalanche amorphous selenium for medical imaging.

PubMed

Scheuermann, James R; Goldan, Amir H; Tousignant, Olivier; Léveillé, Sébastien; Zhao, Wei

2015-03-01

Active matrix flat panel imagers (AMFPI) have limited performance in low dose applications due to the electronic noise of the thin film transistor (TFT) array. A uniform layer of avalanche amorphous selenium (a-Se) called high gain avalanche rushing photoconductor (HARP) allows for signal amplification prior to readout from the TFT array, largely eliminating the effects of the electronic noise. The authors report preliminary avalanche gain measurements from the first HARP structure developed for direct deposition onto a TFT array. The HARP structure is fabricated on a glass substrate in the form of p-i-n, i.e., the electron blocking layer (p) followed by an intrinsic (i) a-Se layer and finally the hole blocking layer (n). All deposition procedures are scalable to large area detectors. Integrated charge is measured from pulsed optical excitation incident on the top electrode (as would in an indirect AMFPI) under continuous high voltage bias. Avalanche gain measurements were obtained from samples fabricated simultaneously at different locations in the evaporator to evaluate performance uniformity across large area. An avalanche gain of up to 80 was obtained, which showed field dependence consistent with previous measurements from n-i-p HARP structures established for vacuum tubes. Measurements from multiple samples demonstrate the spatial uniformity of performance using large area deposition methods. Finally, the results were highly reproducible during the time course of the entire study. We present promising avalanche gain measurement results from a novel HARP structure that can be deposited onto a TFT array. This is a crucial step toward the practical feasibility of AMFPI with avalanche gain, enabling quantum noise limited performance down to a single x-ray photon per pixel.

Array servo scanning micro EDM of 3D micro cavities

NASA Astrophysics Data System (ADS)

Tong, Hao; Li, Yong; Yi, Futing

2011-05-01

Micro electro discharge machining (Micro EDM) is a non-traditional processing technology with the special advantages of low set-up cost and few cutting force in machining any conductive materials regardless of their hardness. As well known, die-sinking EDM is unsuitable for machining the complex 3D micro cavity less than 1mm due to the high-priced fabrication of 3D microelectrode itself and its serous wear during EDM process. In our former study, a servo scanning 3D micro-EDM (3D SSMEDM) method was put forward, and our experiments showed it was available to fabricate complex 3D micro-cavities. In this study, in order to improve machining efficiency and consistency accuracy for array 3D micro-cavities, an array-servo-scanning 3D micro EDM (3D ASSMEDM) method is presented considering the complementary advantages of the 3D SSMEDM and the array micro electrodes with simple cross-section. During 3D ASSMEDM process, the array cavities designed by CAD / CAM system can be batch-manufactured by servo scanning layer by layer using array-rod-like micro tool electrodes, and the axial wear of the array electrodes is compensated in real time by keeping discharge gap. To verify the effectiveness of the 3D ASSMEDM, the array-triangle-micro cavities (side length 630 μm) are batch-manufactured on P-doped silicon by applying the array-micro-electrodes with square-cross-section fabricated by LIGA process. Our exploratory experiment shows that the 3D ASSMEDM provides a feasible approach for the batch-manufacture of 3D array-micro-cavities of conductive materials.

Flexible amorphous silicon PIN diode x-ray detectors

NASA Astrophysics Data System (ADS)

Marrs, Michael; Bawolek, Edward; Smith, Joseph T.; Raupp, Gregory B.; Morton, David

2013-05-01

A low temperature amorphous silicon (a-Si) thin film transistor (TFT) and amorphous silicon PIN photodiode technology for flexible passive pixel detector arrays has been developed using active matrix display technology. The flexible detector arrays can be conformed to non-planar surfaces with the potential to detect x-rays or other radiation with an appropriate conversion layer. The thin, lightweight, and robust backplanes may enable the use of highly portable x-ray detectors for use in the battlefield or in remote locations. We have fabricated detector arrays up to 200 millimeters along the diagonal on a Gen II (370 mm x 470 mm rectangular substrate) using plasma enhanced chemical vapor deposition (PECVD) a-Si as the active layer and PECVD silicon nitride (SiN) as the gate dielectric and passivation. The a-Si based TFTs exhibited an effective saturation mobility of 0.7 cm2/V-s, which is adequate for most sensing applications. The PIN diode material was fabricated using a low stress amorphous silicon (a-Si) PECVD process. The PIN diode dark current was 1.7 pA/mm2, the diode ideality factor was 1.36, and the diode fill factor was 0.73. We report on the critical steps in the evolution of the backplane process from qualification of the low temperature (180°C) TFT and PIN diode process on the 150 mm pilot line, the transfer of the process to flexible plastic substrates, and finally a discussion and demonstration of the scale-up to the Gen II (370 x 470 mm) panel scale pilot line.

Morphological Influence of Solution-Processed Zinc Oxide Films on Electrical Characteristics of Thin-Film Transistors.

PubMed

Lee, Hyeonju; Zhang, Xue; Hwang, Jaeeun; Park, Jaehoon

2016-10-19

We report on the morphological influence of solution-processed zinc oxide (ZnO) semiconductor films on the electrical characteristics of ZnO thin-film transistors (TFTs). Different film morphologies were produced by controlling the spin-coating condition of a precursor solution, and the ZnO films were analyzed using atomic force microscopy, X-ray diffraction, X-ray photoemission spectroscopy, and Hall measurement. It is shown that ZnO TFTs have a superior performance in terms of the threshold voltage and field-effect mobility, when ZnO crystallites are more densely packed in the film. This is attributed to lower electrical resistivity and higher Hall mobility in a densely packed ZnO film. In the results of consecutive TFT operations, a positive shift in the threshold voltage occurred irrespective of the film morphology, but the morphological influence on the variation in the field-effect mobility was evident. The field-effect mobility in TFTs having a densely packed ZnO film increased continuously during consecutive TFT operations, which is in contrast to the mobility decrease observed in the less packed case. An analysis of the field-effect conductivities ascribes these results to the difference in energetic traps, which originate from structural defects in the ZnO films. Consequently, the morphological influence of solution-processed ZnO films on the TFT performance can be understood through the packing property of ZnO crystallites.

Morphological Influence of Solution-Processed Zinc Oxide Films on Electrical Characteristics of Thin-Film Transistors

PubMed Central

Lee, Hyeonju; Zhang, Xue; Hwang, Jaeeun; Park, Jaehoon

2016-01-01

We report on the morphological influence of solution-processed zinc oxide (ZnO) semiconductor films on the electrical characteristics of ZnO thin-film transistors (TFTs). Different film morphologies were produced by controlling the spin-coating condition of a precursor solution, and the ZnO films were analyzed using atomic force microscopy, X-ray diffraction, X-ray photoemission spectroscopy, and Hall measurement. It is shown that ZnO TFTs have a superior performance in terms of the threshold voltage and field-effect mobility, when ZnO crystallites are more densely packed in the film. This is attributed to lower electrical resistivity and higher Hall mobility in a densely packed ZnO film. In the results of consecutive TFT operations, a positive shift in the threshold voltage occurred irrespective of the film morphology, but the morphological influence on the variation in the field-effect mobility was evident. The field-effect mobility in TFTs having a densely packed ZnO film increased continuously during consecutive TFT operations, which is in contrast to the mobility decrease observed in the less packed case. An analysis of the field-effect conductivities ascribes these results to the difference in energetic traps, which originate from structural defects in the ZnO films. Consequently, the morphological influence of solution-processed ZnO films on the TFT performance can be understood through the packing property of ZnO crystallites. PMID:28773973

Exposure to volatile organic compounds and kidney dysfunction in thin film transistor liquid crystal display (TFT-LCD) workers.

PubMed

Chang, Ta-Yuan; Huang, Kuei-Hung; Liu, Chiu-Shong; Shie, Ruei-Hao; Chao, Keh-Ping; Hsu, Wen-Hsin; Bao, Bo-Ying

2010-06-15

Many volatile organic compounds (VOCs) are emitted during the manufacturing of thin film transistor liquid crystal displays (TFT-LCDs), exposure to some of which has been reported to be associated with kidney dysfunction, but whether such an effect exists in TFT-LCD industry workers is unknown. This cross-sectional study aimed to investigate the association between exposure to VOCs and kidney dysfunction among TFT-LCD workers. The results showed that ethanol (1811.0+/-1740.4 ppb), acetone (669.0+/-561.0 ppb), isopropyl alcohol (187.0+/-205.3 ppb) and propylene glycol monomethyl ether acetate (PGMEA) (102.9+/-102.0 ppb) were the four dominant VOCs present in the workplace. The 63 array workers studied had a risk of kidney dysfunction 3.21-fold and 3.84-fold that of 61 cell workers and 18 module workers, respectively. Workers cumulatively exposed to a total level of isopropyl alcohol, PGMEA and propylene glycol monomethyl ether> or =324 ppb-year had a significantly higher risk of kidney dysfunction (adjusted OR=3.41, 95% CI=1.14-10.17) compared with those exposed to <25 ppb-year after adjustment for potential confounding factors. These findings indicated that array workers might be the group at greatest risk of kidney dysfunction within the TFT-LCD industry, and cumulative exposure to specific VOCs might be associated with kidney dysfunction. Crown Copyright 2010. Published by Elsevier B.V. All rights reserved.

Flexible AMOLED backplane using pentacene TFT

NASA Astrophysics Data System (ADS)

Song, Chung Kun; Ryu, Gi Seong

2005-01-01

In this paper we fabricated a panel consisting of an array of organic TFTs (OTFT) and organic LEDs (OLED) in order to demonstrate the possible application of OTFTs to flexible active matrix OLED (AMOLED). The panel was composed of 64×64 pixels on 4 inch size PET substrate in which each pixel had one OTFT integrated with one green OLED. The panel successfully demonstrated to display some letters and pictures by emitting green light with luminance of 20 cd/m2 at 6 V, which was controlled by the gate voltage of OTFT. In addition we also developed fabrication processes for pentacene TFT with PVP gate on PET substrate. The OTFTs produced the maximum mobility of 1.2 cm2/V"sec and on/off current ratio of 2×106.

A Fully Integrated Materials Framework for Enabling the Wireless Detection of Micro-defects in Aging and Battle-worn Structures

DTIC Science & Technology

2012-05-01

field-programmable gate array (FPGA) uses digital signal processing (DSP) algorithms to decode echo-location information from the backscattered signal ...characterizing and understanding of the physical properties of the BST and PZT thin films. Using microwave reflection spectroscopy, the complex...acoustic data, , would be encoded in the reflected MW signal by means of phase modulation (PM). By using high-Q resonators as the reactive

Low-temperature fabrication of sputtered high-k HfO2 gate dielectric for flexible a-IGZO thin film transistors

NASA Astrophysics Data System (ADS)

Yao, Rihui; Zheng, Zeke; Xiong, Mei; Zhang, Xiaochen; Li, Xiaoqing; Ning, Honglong; Fang, Zhiqiang; Xie, Weiguang; Lu, Xubing; Peng, Junbiao

2018-03-01

In this work, low temperature fabrication of a sputtered high-k HfO2 gate dielectric for flexible a-IGZO thin film transistors (TFTs) on polyimide substrates was investigated. The effects of Ar-pressure during the sputtering process and then especially the post-annealing treatments at low temperature (≤200 °C) for HfO2 on reducing the density of defects in the bulk and on the surface were systematically studied. X-ray reflectivity, UV-vis and X-ray photoelectron spectroscopy, and micro-wave photoconductivity decay measurements were carried out and indicated that the high quality of optimized HfO2 film and its high dielectric properties contributed to the low concentration of structural defects and shallow localized defects such as oxygen vacancies. As a result, the well-structured HfO2 gate dielectric exhibited a high density of 9.7 g/cm3, a high dielectric constant of 28.5, a wide optical bandgap of 4.75 eV, and relatively low leakage current. The corresponding flexible a-IGZO TFT on polyimide exhibited an optimal device performance with a saturation mobility of 10.3 cm2 V-1 s-1, an Ion/Ioff ratio of 4.3 × 107, a SS value of 0.28 V dec-1, and a threshold voltage (Vth) of 1.1 V, as well as favorable stability under NBS/PBS gate bias and bending stress.

Servo scanning 3D micro EDM for array micro cavities using on-machine fabricated tool electrodes

NASA Astrophysics Data System (ADS)

Tong, Hao; Li, Yong; Zhang, Long

2018-02-01

Array micro cavities are useful in many fields including in micro molds, optical devices, biochips and so on. Array servo scanning micro electro discharge machining (EDM), using array micro electrodes with simple cross-sectional shape, has the advantage of machining complex 3D micro cavities in batches. In this paper, the machining errors caused by offline-fabricated array micro electrodes are analyzed in particular, and then a machining process of array servo scanning micro EDM is proposed by using on-machine fabricated array micro electrodes. The array micro electrodes are fabricated on-machine by combined procedures including wire electro discharge grinding, array reverse copying and electrode end trimming. Nine-array tool electrodes with Φ80 µm diameter and 600 µm length are obtained. Furthermore, the proposed process is verified by several machining experiments for achieving nine-array hexagonal micro cavities with top side length of 300 µm, bottom side length of 150 µm, and depth of 112 µm or 120 µm. In the experiments, a chip hump accumulates on the electrode tips like the built-up edge in mechanical machining under the conditions of brass workpieces, copper electrodes and the dielectric of deionized water. The accumulated hump can be avoided by replacing the water dielectric by an oil dielectric.

Efficient Defect Engineering for Solution Combustion Processed In-Zn-O thin films for high performance transistors

NASA Astrophysics Data System (ADS)

Liang, Xiaoci; Wang, Chengcai; Liang, Jun; Liu, Chuan; Pei, Yanli

2017-09-01

The oxygen related defects in the solution combustion-processed InZnO vitally affect the field-effect mobility and on-off characteristics in thin film transistors (TFTs). We use photoelectron spectroscopy to reveal that these defects can be well controlled by adjusting the atmosphere and flow rate during the combustion reaction, but are hardly affected by further post-annealing after the reaction. In device performance, the threshold voltage of the InZnO-TFTs was regulated in a wide range from 3.5 V to 11.0 V. To compromise the high field-effect mobility and good subthreshold properties, we fabricate the TFTs with double active layers of InZnO to achieve vertical gradience in defect distribution. The resulting TFT exhibits much higher field-effect mobility as 17.5 cm2 · V-1 · s-1, a low reversed sub-threshold slope as 0.35 V/decade, and a high on-off ratio as 107. The presented understandings and methods on defect engineering are efficient in improving the device performance of TFTs made from the combustion reaction process.

Transparent Fingerprint Sensor System for Large Flat Panel Display.

PubMed

Seo, Wonkuk; Pi, Jae-Eun; Cho, Sung Haeung; Kang, Seung-Youl; Ahn, Seong-Deok; Hwang, Chi-Sun; Jeon, Ho-Sik; Kim, Jong-Uk; Lee, Myunghee

2018-01-19

In this paper, we introduce a transparent fingerprint sensing system using a thin film transistor (TFT) sensor panel, based on a self-capacitive sensing scheme. An armorphousindium gallium zinc oxide (a-IGZO) TFT sensor array and associated custom Read-Out IC (ROIC) are implemented for the system. The sensor panel has a 200 × 200 pixel array and each pixel size is as small as 50 μm × 50 μm. The ROIC uses only eight analog front-end (AFE) amplifier stages along with a successive approximation analog-to-digital converter (SAR ADC). To get the fingerprint image data from the sensor array, the ROIC senses a capacitance, which is formed by a cover glass material between a human finger and an electrode of each pixel of the sensor array. Three methods are reviewed for estimating the self-capacitance. The measurement result demonstrates that the transparent fingerprint sensor system has an ability to differentiate a human finger's ridges and valleys through the fingerprint sensor array.

Transparent Fingerprint Sensor System for Large Flat Panel Display

PubMed Central

Seo, Wonkuk; Pi, Jae-Eun; Cho, Sung Haeung; Kang, Seung-Youl; Ahn, Seong-Deok; Hwang, Chi-Sun; Jeon, Ho-Sik; Kim, Jong-Uk

2018-01-01

In this paper, we introduce a transparent fingerprint sensing system using a thin film transistor (TFT) sensor panel, based on a self-capacitive sensing scheme. An armorphousindium gallium zinc oxide (a-IGZO) TFT sensor array and associated custom Read-Out IC (ROIC) are implemented for the system. The sensor panel has a 200 × 200 pixel array and each pixel size is as small as 50 μm × 50 μm. The ROIC uses only eight analog front-end (AFE) amplifier stages along with a successive approximation analog-to-digital converter (SAR ADC). To get the fingerprint image data from the sensor array, the ROIC senses a capacitance, which is formed by a cover glass material between a human finger and an electrode of each pixel of the sensor array. Three methods are reviewed for estimating the self-capacitance. The measurement result demonstrates that the transparent fingerprint sensor system has an ability to differentiate a human finger’s ridges and valleys through the fingerprint sensor array. PMID:29351218

Chemically amplified i-line positive resist for next-generation flat panel display

NASA Astrophysics Data System (ADS)

Lee, Hsing-Chieh; Lu, Ying-Hao; Huang, Shin-Yih; Lan, Wei-Jen; Hanabata, Makoto

2017-03-01

Traditional diazonaphthoquinone (DNQ) positive photoresists are widely used for TFT-LCD array process. Current LTPS technology has more than 600ppi resolution is required for small or middle-sized TFT liquid crystal display panels. One of the ways to enhance resolution is to apply i-line single exposure system instead of traditional g/h/ibroadband exposure system. We have been developing i-line chemically amplified photoresist ECA 200 series for the next generation flat panel display (FPD). ECA 200 consists of three components: a phenol resin, a photo acid generator and dissolution enhancer. We applied two different types of dissolution enhancers with two different kinds of protected groups to our resist materials. As a result, we achieved higher sensitivity, higher resolution, less footing of the resist profile and reduced standing wave effect compared with traditional DNQ photoresists. In addition, we have found further property of photoresist that does not need post exposure bake (PEB) process. This resist has a great advantage at most of current panel plants without PEB process.

A front-end wafer-level microsystem packaging technique with micro-cap array

NASA Astrophysics Data System (ADS)

Chiang, Yuh-Min

2002-09-01

The back-end packaging process is the remaining challenge for the micromachining industry to commercialize microsystem technology (MST) devices at low cost. This dissertation presents a novel wafer level protection technique as a final step of the front-end fabrication process for MSTs. It facilitates improved manufacturing throughput and automation in package assembly, wafer level testing of devices, and enhanced device performance. The method involves the use of a wafer-sized micro-cap array, which consists of an assortment of small caps micro-molded onto a material with adjustable shapes and sizes to serve as protective structures against the hostile environments during packaging. The micro-cap array is first constructed by a micromachining process with micro-molding technique, then sealed to the device wafer at wafer level. Epoxy-based wafer-level micro cap array has been successfully fabricated and showed good compatibility with conventional back-end packaging processes. An adhesive transfer technique was demonstrated to seal the micro cap array with a MEMS device wafer. No damage or gross leak was observed while wafer dicing or later during a gross leak test. Applications of the micro cap array are demonstrated on MEMS, microactuators fabricated using CRONOS MUMPS process. Depending on the application needs, the micro-molded cap can be designed and modified to facilitate additional component functions, such as optical, electrical, mechanical, and chemical functions, which are not easily achieved in the device by traditional means. Successful fabrication of a micro cap array comprised with microlenses can provide active functions as well as passive protection. An optical tweezer array could be one possibility for applications of a micro cap with microlenses. The micro cap itself could serve as micro well for DNA or bacteria amplification as well.

Process for the detection of micro-cracks

DOEpatents

Lapinski, Norman; Sather, Allen

1979-01-01

A process for the nondestructive testing of ceramic objects to detect the presence of defects and micro-cracks in the surface in which a solution of silver nitrate is applied to the surface of the object which penetrates into the surface defects, drying the object so that the silver nitrate remains in the defects, and preparing an X-ray radiograph whereby any defects and micro-cracks will appear in the radiograph.

Current progress and technical challenges of flexible liquid crystal displays

NASA Astrophysics Data System (ADS)

Fujikake, Hideo; Sato, Hiroto

2009-02-01

We focused on several technical approaches to flexible liquid crystal (LC) display in this report. We have been developing flexible displays using plastic film substrates based on polymer-dispersed LC technology with molecular alignment control. In our representative devices, molecular-aligned polymer walls keep plastic-substrate gap constant without LC alignment disorder, and aligned polymer networks create monostable switching of fast-response ferroelectric LC (FLC) for grayscale capability. In the fabrication process, a high-viscosity FLC/monomer solution was printed, sandwiched and pressed between plastic substrates. Then the polymer walls and networks were sequentially formed based on photo-polymerization-induced phase separation in the nematic phase by two exposure processes of patterned and uniform ultraviolet light. The two flexible backlight films of direct illumination and light-guide methods using small three-primary-color light-emitting diodes were fabricated to obtain high-visibility display images. The fabricated flexible FLC panels were driven by external transistor arrays, internal organic thin film transistor (TFT) arrays, and poly-Si TFT arrays. We achieved full-color moving-image displays using the flexible FLC panel and the flexible backlight film based on field-sequential-color driving technique. Otherwise, for backlight-free flexible LC displays, flexible reflective devices of twisted guest-host nematic LC and cholesteric LC were discussed with molecular-aligned polymer walls. Singlesubstrate device structure and fabrication method using self-standing polymer-stabilized nematic LC film and polymer ceiling layer were also proposed for obtaining LC devices with excellent flexibility.

Spontaneous assembly of chemically encoded two-dimensional coacervate droplet arrays by acoustic wave patterning

PubMed Central

Tian, Liangfei; Martin, Nicolas; Bassindale, Philip G.; Patil, Avinash J.; Li, Mei; Barnes, Adrian; Drinkwater, Bruce W.; Mann, Stephen

2016-01-01

The spontaneous assembly of chemically encoded, molecularly crowded, water-rich micro-droplets into periodic defect-free two-dimensional arrays is achieved in aqueous media by a combination of an acoustic standing wave pressure field and in situ complex coacervation. Acoustically mediated coalescence of primary droplets generates single-droplet per node micro-arrays that exhibit variable surface-attachment properties, spontaneously uptake dyes, enzymes and particles, and display spatial and time-dependent fluorescence outputs when exposed to a reactant diffusion gradient. In addition, coacervate droplet arrays exhibiting dynamical behaviour and exchange of matter are prepared by inhibiting coalescence to produce acoustically trapped lattices of droplet clusters that display fast and reversible changes in shape and spatial configuration in direct response to modulations in the acoustic frequencies and fields. Our results offer a novel route to the design and construction of ‘water-in-water' micro-droplet arrays with controllable spatial organization, programmable signalling pathways and higher order collective behaviour. PMID:27708286

Nitrogen anion doping as a strategy to suppress negative gate-bias illumination instability of ZnSnO thin film transistor

NASA Astrophysics Data System (ADS)

Li, Jun; Fu, Yi-Zhou; Huang, Chuan-Xin; Zhang, Jian-Hua; Jiang, Xue-Yin; Zhang, Zhi-Lin

2016-04-01

This work presents a strategy of nitrogen anion doping to suppress negative gate-bias illumination instability. The electrical performance and negative gate-bias illumination stability of the ZnSnON thin film transistors (TFTs) are investigated. Compared with ZnSnO-TFT, ZnSnON-TFT has a 53% decrease in the threshold voltage shift under negative bias illumination stress and electrical performance also progresses obviously. The stability improvement of ZnSnON-TFT is attributed to the reduction in ionized oxygen vacancy defects and the photodesorption of oxygen-related molecules. It suggests that anion doping can provide an effective solution to the adverse tradeoff between field effect mobility and negative bias illumination stability.

A Simple Method for High-Performance, Solution-Processed, Amorphous ZrO2 Gate Insulator TFT with a High Concentration Precursor

PubMed Central

Cai, Wei; Zhu, Zhennan; Wei, Jinglin; Fang, Zhiqiang; Zheng, Zeke; Zhou, Shangxiong; Peng, Junbiao; Lu, Xubing

2017-01-01

Solution-processed high-k dielectric TFTs attract much attention since they cost relatively little and have a simple fabrication process. However, it is still a challenge to reduce the leakage of the current density of solution-processed dielectric TFTs. Here, a simple solution method is presented towards enhanced performance of ZrO2 films by intentionally increasing the concentration of precursor. The ZrO2 films not only exhibit a low leakage current density of 10−6 A/cm2 at 10 V and a breakdown field of 2.5 MV/cm, but also demonstrate a saturation mobility of 12.6 cm2·V−1·s−1 and a Ion/Ioff ratio of 106 in DC pulse sputtering IGZO-TFTs based on these films. Moreover, the underlying mechanism of influence of precursor concentration on film formation is presented. Higher concentration precursor results in a thicker film within same coating times with reduced ZrO2/IGZO interface defects and roughness. It shows the importance of thickness, roughness, and annealing temperature in solution-processed dielectric oxide TFT and provides an approach to precisely control solution-processed oxide films thickness. PMID:28825652

A Simple Method for High-Performance, Solution-Processed, Amorphous ZrO₂ Gate Insulator TFT with a High Concentration Precursor.

PubMed

Cai, Wei; Zhu, Zhennan; Wei, Jinglin; Fang, Zhiqiang; Ning, Honglong; Zheng, Zeke; Zhou, Shangxiong; Yao, Rihui; Peng, Junbiao; Lu, Xubing

2017-08-21

Solution-processed high-k dielectric TFTs attract much attention since they cost relatively little and have a simple fabrication process. However, it is still a challenge to reduce the leakage of the current density of solution-processed dielectric TFTs. Here, a simple solution method is presented towards enhanced performance of ZrO₂ films by intentionally increasing the concentration of precursor. The ZrO₂ films not only exhibit a low leakage current density of 10 -6 A/cm² at 10 V and a breakdown field of 2.5 MV/cm, but also demonstrate a saturation mobility of 12.6 cm²·V -1 ·s -1 and a I on /I off ratio of 10⁶ in DC pulse sputtering IGZO-TFTs based on these films. Moreover, the underlying mechanism of influence of precursor concentration on film formation is presented. Higher concentration precursor results in a thicker film within same coating times with reduced ZrO₂/IGZO interface defects and roughness. It shows the importance of thickness, roughness, and annealing temperature in solution-processed dielectric oxide TFT and provides an approach to precisely control solution-processed oxide films thickness.

MBR/RO/ozone processes for TFT-LCD industrial wastewater treatment and recycling.

PubMed

Chen, T K; Ni, C H; Chan, Y C; Lu, M C

2005-01-01

This research is mainly to explore the treatment capacity for TFT-LCD industrial wastewater recycling by the processes combined with membrane bioreactor (MBR), reverse osmosis (RO) and ozone(O3). The organic wastewater from the TFT-LCD industry was selected as the target. MBR, RO and ozone plants were established for evaluation. An MBR plant consisted of a 2-stage anoxic/aerobic bioreactor and an immersed UF membrane unit was employed. The effluent of MBR was conducted into the RO system then into the ozone system. The RO system consisted of a spiral membrane in the vessel. One bubble column, 75 cm high and diameter 5 cm, were used as the ozonation reactor. On the bottom of ozonation reactor is a porous diffuser for releasing gas, with an aperture of 100 microm (0.1 cm). Over the whole experimental period, the MBR process achieved a satisfactory organic removal. The COD could be removed with an average of over 98.5%. For the TOC item, the average removal efficiency was 97.4%. The stable effluent quality and satisfactory removal performance were ensured by the efficient interception performance of an immersed UF membrane device incorporated with the biological reactor. Moreover, the MBR effluent did not contain any suspended solids and the SDI value was under 3. After the treatment of RO, excellent water quality was found. The water quality of permeate was under 5 mg/I, 2 mg/l and 50 micros/cm for COD, TOC and conductivity respectively. The treated water can be recycled and reused for the cooling tower make-up water or other purposes. After the treatment of ozone, the treated water quality was under 5 mg/l and 0.852 mg/l for COD and TOC respectively. The test results of MBR, MBR/RO and MBR/RO/ozone processes were compared as possible appropriate treatment technologies applied in TFT-LCD industrial wastewater reuse and recycling.

Amorphous In-Ga-Zn-O Thin Film Transistor Current-Scaling Pixel Electrode Circuit for Active-Matrix Organic Light-Emitting Displays

NASA Astrophysics Data System (ADS)

Chen, Charlene; Abe, Katsumi; Fung, Tze-Ching; Kumomi, Hideya; Kanicki, Jerzy

2009-03-01

In this paper, we analyze application of amorphous In-Ga-Zn-O thin film transistors (a-InGaZnO TFTs) to current-scaling pixel electrode circuit that could be used for 3-in. quarter video graphics array (QVGA) full color active-matrix organic light-emitting displays (AM-OLEDs). Simulation results, based on a-InGaZnO TFT and OLED experimental data, show that both device sizes and operational voltages can be reduced when compare to the same circuit using hydrogenated amorphous silicon (a-Si:H) TFTs. Moreover, the a-InGaZnO TFT pixel circuit can compensate for the drive TFT threshold voltage variation (ΔVT) within acceptable operating error range.

The Influence of Hafnium Doping on Density of States in Zinc Oxide Thin-Film Transistors Deposited via Atomic Layer Deposition.

PubMed

Ding, Xingwei; Qin, Cunping; Song, Jiantao; Zhang, Jianhua; Jiang, Xueyin; Zhang, Zhilin

2017-12-01

Thin-film transistors (TFTs) with atomic layer deposition (ALD) HfZnO (HZO) as channel layer and Al 2 O 3 as gate insulator were successfully fabricated. Compared with ZnO-TFT, the stability of HZO-TFT was obviously improved as Hf doping can suppress the generation of oxygen related defects. The transfer characteristics of TFTs at different temperatures were also investigated, and temperature stability enhancement was observed for the TFT with Hf doping. The density of states (DOS) was calculated based on the experimentally obtained E a , which can explain the experimental observation. A high-field effect mobility of 9.4 cm 2 /Vs, a suitable turn-on voltage of 0.26 V, a high on/off ratio of over 10 7 and a steep sub-threshold swing of 0.3 V/decade were obtained in HZO-TFT. The results showed that temperature stability enhancement in HfZnO thin-film transistors are attributed to the smaller DOS.

The Influence of Hafnium Doping on Density of States in Zinc Oxide Thin-Film Transistors Deposited via Atomic Layer Deposition

NASA Astrophysics Data System (ADS)

Ding, Xingwei; Qin, Cunping; Song, Jiantao; Zhang, Jianhua; Jiang, Xueyin; Zhang, Zhilin

2017-01-01

Thin-film transistors (TFTs) with atomic layer deposition (ALD) HfZnO (HZO) as channel layer and Al2O3 as gate insulator were successfully fabricated. Compared with ZnO-TFT, the stability of HZO-TFT was obviously improved as Hf doping can suppress the generation of oxygen related defects. The transfer characteristics of TFTs at different temperatures were also investigated, and temperature stability enhancement was observed for the TFT with Hf doping. The density of states (DOS) was calculated based on the experimentally obtained E a, which can explain the experimental observation. A high-field effect mobility of 9.4 cm2/Vs, a suitable turn-on voltage of 0.26 V, a high on/off ratio of over 107 and a steep sub-threshold swing of 0.3 V/decade were obtained in HZO-TFT. The results showed that temperature stability enhancement in HfZnO thin-film transistors are attributed to the smaller DOS.

Effects of various gate materials on electrical degradation of a-Si:H TFT in industrial display application

NASA Astrophysics Data System (ADS)

Ho, Ching-Yuan; Chang, Yaw-Jen

2016-02-01

Both aluminum (Al) and copper (Cu), acting as transmission lines in the hydrogenated amorphous silicon of a thin film transistor (a-Si:H TFT), were studied to investigate electrical degradation including electron-migration (EM) and threshold voltage (Vt) stability and recovery performance. Under long-term current stress, the Cu material exhibited excellent resistance to EM properties, but a passivated SiNx crack was observed due to fast heat conductivity. By applying electrical stress on the gate and drain for 5 × 104 s, the power-law time dependency of the threshold voltage shift (ΔVt) indicated that the defective state creation dominated the TFT device's instability. The presence of drain stress increased the overall ΔVt because the high longitudinal field induced impact ionization and then, enhanced hot-carrier-induced electron trapping within the gate SiNx dielectric. An annealing effect prompted a stressed a-Si:H TFT back to virgin status. This study proposes better ΔVt stability and excellent resistance against electron-migration in a Cu gate device which can be considered as a candidate for a transmission line on prolonged TFT applications.

Experimental research on micro-pit defects of SUS 430 stainless steel strip in cold rolling process

NASA Astrophysics Data System (ADS)

Li, Changsheng; Li, Miao; Zhu, Tao; Huo, Gang

2013-05-01

In order to improve surface glossiness of stainless steel strip in tandem cold rolling, experimental research on micro-pit defects of SUS 430 ferrite stainless steel was investigated in laboratory. The surface morphology of micro-pit defects was observed by SEM. The effects of micro-pit defects on rolling reduction, roll surface roughness and emulsion parameters were analyzed. With the pass number increasing, the quantity and surface of micro-pit defects were reduced, uneven peak was decreased and gently along rolling direction, micro-pit defects had equally distributed tendency along tranverse direction. The micro-pit defects were increased with the roll surface roughness increase. The defects ratio was declined with larger gradient at pass number 1 to 3, but gentle slope at pass number 4 to 5. The effects of temperature 55° and 63°, concentration 3% and 6% of emulsion on micro-pit effects had not obvious difference. Maintain of micro-pit was effected by rolling oil or air in the micro-pit, the quality of oil was much more than the air in the micro-pit in lubrication rolling.

TiN/Al2O3/ZnO gate stack engineering for top-gate thin film transistors by combination of post oxidation and annealing

NASA Astrophysics Data System (ADS)

Kato, Kimihiko; Matsui, Hiroaki; Tabata, Hitoshi; Takenaka, Mitsuru; Takagi, Shinichi

2018-04-01

Control of fabrication processes for a gate stack structure with a ZnO thin channel layer and an Al2O3 gate insulator has been examined for enhancing the performance of a top-gate ZnO thin film transistor (TFT). The Al2O3/ZnO interface and the ZnO layer are defective just after the Al2O3 layer formation by atomic layer deposition. Post treatments such as plasma oxidation, annealing after the Al2O3 deposition, and gate metal formation (PMA) are promising to improve the interfacial and channel layer qualities drastically. Post-plasma oxidation effectively reduces the interfacial defect density and eliminates Fermi level pinning at the Al2O3/ZnO interface, which is essential for improving the cut-off of the drain current of TFTs. A thermal effect of post-Al2O3 deposition annealing at 350 °C can improve the crystalline quality of the ZnO layer, enhancing the mobility. On the other hand, impacts of post-Al2O3 deposition annealing and PMA need to be optimized because the annealing can also accompany the increase in the shallow-level defect density and the resulting electron concentration, in addition to the reduction in the deep-level defect density. The development of the interfacial control technique has realized the excellent TFT performance with a large ON/OFF ratio, steep subthreshold characteristics, and high field-effect mobility.

Fabrication of polymer micro-lens array with pneumatically diaphragm-driven drop-on-demand inkjet technology.

PubMed

Xie, Dan; Zhang, Honghai; Shu, Xiayun; Xiao, Junfeng

2012-07-02

The paper reports an effective method to fabricate micro-lens arrays with the ultraviolet-curable polymer, using an original pneumatically diaphragm-driven drop-on-demand inkjet system. An array of plano convex micro-lenses can be formed on the glass substrate due to surface tension and hydrophobic effect. The micro-lens arrays have uniform focusing function, smooth and real planar surface. The fabrication process showed good repeatability as well, fifty micro-lenses randomly selected form 9 × 9 miro-lens array with an average diameter of 333.28μm showed 1.1% variations. Also, the focal length, the surface roughness and optical property of the fabricated micro-lenses are measured, analyzed and proved satisfactory. The technique shows great potential for fabricating polymer micro-lens arrays with high flexibility, simple technological process and low production cost.

Fabrication of amorphous IGZO thin film transistor using self-aligned imprint lithography with a sacrificial layer

NASA Astrophysics Data System (ADS)

Kim, Sung Jin; Kim, Hyung Tae; Choi, Jong Hoon; Chung, Ho Kyoon; Cho, Sung Min

2018-04-01

An amorphous indium-gallium-zinc-oxide (a-IGZO) thin film transistor (TFT) was fabricated by a self-aligned imprint lithography (SAIL) method with a sacrificial photoresist layer. The SAIL is a top-down method to fabricate a TFT using a three-dimensional multilayer etch mask having all pattern information for the TFT. The sacrificial layer was applied in the SAIL process for the purpose of removing the resin residues that were inevitably left when the etch mask was thinned by plasma etching. This work demonstrated that the a-IGZO TFT could be fabricated by the SAIL process with the sacrificial layer. Specifically, the simple fabrication process utilized in this study can be utilized for the TFT with a plasma-sensitive semiconductor such as the a-IGZO and further extended for the roll-to-roll TFT fabrication.

Highly stable field emission from ZnO nanowire field emitters controlled by an amorphous indium–gallium–zinc-oxide thin film transistor

NASA Astrophysics Data System (ADS)

Li, Xiaojie; Wang, Ying; Zhang, Zhipeng; Ou, Hai; She, Juncong; Deng, Shaozhi; Xu, Ningsheng; Chen, Jun

2018-04-01

Lowering the driving voltage and improving the stability of nanowire field emitters are essential for them to be applied in devices. In this study the characteristics of zinc oxide (ZnO) nanowire field emitter arrays (FEAs) controlled by an amorphous indium–gallium–zinc-oxide thin film transistor (a-IGZO TFT) were studied. A low driving voltage along with stabilization of the field emission current were achieved. Modulation of field emission currents up to three orders of magnitude was achieved at a gate voltage of 0–32 V for a constant anode voltage. Additionally, a-IGZO TFT control can dramatically reduce the emission current fluctuation (i.e., from 46.11 to 1.79% at an emission current of ∼3.7 µA). Both the a-IGZO TFT and ZnO nanowire FEAs were prepared on glass substrates in our research, demonstrating the feasibility of realizing large area a-IGZO TFT-controlled ZnO nanowire FEAs.

The excuse principle can maintain cooperation through forgivable defection in the Prisoner's Dilemma game

PubMed Central

Krams, Indrikis; Kokko, Hanna; Vrublevska, Jolanta; Āboliņš-Ābols, Mikus; Krama, Tatjana; Rantala, Markus J.

2013-01-01

Reciprocal altruism describes a situation in which an organism acts in a manner that temporarily reduces its fitness while increasing another organism's fitness, but there is an ultimate fitness benefit based on an expectation that the other organism will act in a similar manner at a later time. It creates the obvious dilemma in which there is always a short-term benefit to cheating, therefore cooperating individuals must avoid being exploited by non-cooperating cheaters. This is achieved by following various decision rules, usually variants of the tit-for-tat (TFT) strategy. The strength of TFT, however, is also its weakness—mistakes in implementation or interpretation of moves, or the inability to cooperate, lead to a permanent breakdown in cooperation. We show that pied flycatchers (Ficedula hypoleuca) use a TFT with an embedded ‘excuse principle’ to forgive the neighbours that were perceived as unable to cooperate during mobbing of predators. The excuse principle dramatically increases the stability of TFT-like behavioural strategies within the Prisoner's Dilemma game. PMID:23864603

Localization of multiple defects using the compact phased array (CPA) method

NASA Astrophysics Data System (ADS)

Senyurek, Volkan Y.; Baghalian, Amin; Tashakori, Shervin; McDaniel, Dwayne; Tansel, Ibrahim N.

2018-01-01

Array systems of transducers have found numerous applications in detection and localization of defects in structural health monitoring (SHM) of plate-like structures. Different types of array configurations and analysis algorithms have been used to improve the process of localization of defects. For accurate and reliable monitoring of large structures by array systems, a high number of actuator and sensor elements are often required. In this study, a compact phased array system consisting of only three piezoelectric elements is used in conjunction with an updated total focusing method (TFM) for localization of single and multiple defects in an aluminum plate. The accuracy of the localization process was greatly improved by including wave propagation information in TFM. Results indicated that the proposed CPA approach can locate single and multiple defects with high accuracy while decreasing the processing costs and the number of required transducers. This method can be utilized in critical applications such as aerospace structures where the use of a large number of transducers is not desirable.

Fabrication of a 3D micro/nano dual-scale carbon array and its demonstration as the microelectrodes for supercapacitors

NASA Astrophysics Data System (ADS)

Jiang, Shulan; Shi, Tielin; Gao, Yang; Long, Hu; Xi, Shuang; Tang, Zirong

2014-04-01

An easily accessible method is proposed for the fabrication of a 3D micro/nano dual-scale carbon array with a large surface area. The process mainly consists of three critical steps. Firstly, a hemispherical photoresist micro-array was obtained by the cost-effective nanoimprint lithography process. Then the micro-array was transformed into hierarchical structures with longitudinal nanowires on the microstructure surface by oxygen plasma etching. Finally, the micro/nano dual-scale carbon array was fabricated by carbonizing these hierarchical photoresist structures. It has also been demonstrated that the micro/nano dual-scale carbon array can be used as the microelectrodes for supercapacitors by the electrodeposition of a manganese dioxide (MnO2) film onto the hierarchical carbon structures with greatly enhanced electrochemical performance. The specific gravimetric capacitance of the deposited micro/nano dual-scale microelectrodes is estimated to be 337 F g-1 at the scan rate of 5 mV s-1. This proposed approach of fabricating a micro/nano dual-scale carbon array provides a facile way in large-scale microstructures’ manufacturing for a wide variety of applications, including sensors and on-chip energy storage devices.

Manufacture of high aspect ratio micro-pillar wall shear stress sensor arrays

NASA Astrophysics Data System (ADS)

Gnanamanickam, Ebenezer P.; Sullivan, John P.

2012-12-01

In the field of experimental fluid mechanics the measurement of unsteady, distributed wall shear stress has proved historically challenging. Recently, sensors based on an array of flexible micro-pillars have shown promise in carrying out such measurements. Similar sensors find use in other applications such as cellular mechanics. This work presents a manufacturing technique that can manufacture micro-pillar arrays of high aspect ratio. An electric discharge machine (EDM) is used to manufacture a micro-drilling tool. This micro-drilling tool is used to form holes in a wax sheet which acts as the mold for the micro-pillar array. Silicone rubber is cast in these molds to yield a micro-pillar array. Using this technique, micro-pillar arrays with a maximum aspect ratio of about 10 have been manufactured. Manufacturing issues encountered, steps to alleviate them and the potential of the process to manufacture similar micro-pillar arrays in a time-efficient manner are also discussed.

Amorphous silicon thin film transistor active-matrix organic light-emitting diode displays fabricated on flexible substrates

NASA Astrophysics Data System (ADS)

Nichols, Jonathan A.

Organic light-emitting diode (OLED) displays are of immense interest because they have several advantages over liquid crystal displays, the current dominant flat panel display technology. OLED displays are emissive and therefore are brighter, have a larger viewing angle, and do not require backlights and filters, allowing thinner, lighter, and more power efficient displays. The goal of this work was to advance the state-of-the-art in active-matrix OLED display technology. First, hydrogenated amorphous silicon (a-Si:H) thin film transistor (TFT) active-matrix OLED pixels and arrays were designed and fabricated on glass substrates. The devices operated at low voltages and demonstrated that lower performance TFTs could be utilized in active-matrix OLED displays, possibly allowing lower cost processing and the use of polymeric substrates. Attempts at designing more control into the display at the pixel level were also made. Bistable (one bit gray scale) active-matrix OLED pixels and arrays were designed and fabricated. Such pixels could be used in novel applications and eventually help reduce the bandwidth requirements in high-resolution and large-area displays. Finally, a-Si:H TFT active-matrix OLED pixels and arrays were fabricated on a polymeric substrate. Displays fabricated on a polymeric substrates would be lightweight; flexible, more rugged, and potentially less expensive to fabricate. Many of the difficulties associated with fabricating active-matrix backplanes on flexible substrates were studied and addressed.

Numerical simulation of offset-drain amorphous oxide-based thin-film transistors

NASA Astrophysics Data System (ADS)

Jeong, Jaewook

2016-11-01

In this study, we analyzed the electrical characteristics of amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) with an offset-drain structure by technology computer aided design (TCAD) simulation. When operating in a linear region, an enhancement-type TFT shows poor field-effect mobility because most conduction electrons are trapped in acceptor-like defects in an offset region when the offset length (L off) exceeds 0.5 µm, whereas a depletion-type TFT shows superior field-effect mobility owing to the high free electron density in the offset region compared with the trapped electron density. When operating in the saturation region, both types of TFTs show good field-effect mobility comparable to that of a reference TFT with a large gate overlap. The underlying physics of the depletion and enhancement types of offset-drain TFTs are systematically analyzed.

Study of a new type anode of OLED by MIC poly-Si

NASA Astrophysics Data System (ADS)

Li, Yang; Meng, Zhiguo; Wu, Chunya; Man, Wong; Hoi, Kwok Sing; Xiong, Shaozhen

2007-11-01

In this paper, a boron-doped poly-Si crystallized by solution-based metal induced (S-MIC) as the anode of organic light emitting diode (OLED) was studied. The semi-transparent and semi-reflective anode of OLED systemized with the high reflectivity of Al cathode could form a micro-cavity structure with a low Q to improve the efficiency. The maximum luminance efficiency of red OLED made by Alq3: DCJTB (1.5wt %)( 30nm) with the poly-Si anode is 2.66cd/A, higher than that of the OLED with the ITO anodes by 30%. In order to improve the device performance, some key to optimize the character of MIC poly-Si thin film are analyzed theoretically. A new kind of TFT/OLED coupling structure in AMOLED was proposed, in which the pixel electrode of OLED was made by the same poly-Si thin film with its driver TFT's drain electrode. So that this coupling structure will simplify the AMOLED processes flow.

Enhanced Light Stability of InGaZnO Thin-Film Transistors by Atomic-Layer-Deposited Y2O3 with Ozone.

PubMed

Jung, Hanearl; Kim, Woo-Hee; Park, Bo-Eun; Woo, Whang Je; Oh, Il-Kwon; Lee, Su Jeong; Kim, Yun Cheol; Myoung, Jae-Min; Gatineau, Satoko; Dussarrat, Christian; Kim, Hyungjun

2018-01-17

We report the effect of Y 2 O 3 passivation by atomic layer deposition (ALD) using various oxidants, such as H 2 O, O 2 plasma, and O 3 , on In-Ga-Zn-O thin-film transistors (IGZO TFTs). A large negative shift in the threshold voltage (V th ) was observed in the case of the TFT subjected to the H 2 O-ALD Y 2 O 3 process; this shift was caused by a donor effect of negatively charged chemisorbed H 2 O molecules. In addition, degradation of the IGZO TFT device performance after the O 2 plasma-ALD Y 2 O 3 process (field-effect mobility (μ) = 8.7 cm 2 /(V·s), subthreshold swing (SS) = 0.77 V/dec, and V th = 3.7 V) was observed, which was attributed to plasma damage on the IGZO surface adversely affecting the stability of the TFT under light illumination. In contrast, the O 3 -ALD Y 2 O 3 process led to enhanced device stability under light illumination (ΔV th = -1 V after 3 h of illumination) by passivating the subgap defect states in the IGZO surface region. In addition, TFTs with a thicker IGZO film (55 nm, which was the optimum thickness under the current investigation) showed more stable device performance than TFTs with a thinner IGZO film (30 nm) (ΔV th = -0.4 V after 3 h of light illumination) by triggering the recombination of holes diffusing from the IGZO surface to the insulator-channel interface. Therefore, we envisioned that the O 3 -ALD Y 2 O 3 passivation layer suggested in this paper can improve the photostability of TFTs under light illumination.

Digital radiology using active matrix readout: amplified pixel detector array for fluoroscopy.

PubMed

Matsuura, N; Zhao, W; Huang, Z; Rowlands, J A

1999-05-01

Active matrix array technology has made possible the concept of flat panel imaging systems for radiography. In the conventional approach a thin-film circuit built on glass contains the necessary switching components (thin-film transistors or TFTs) to readout an image formed in either a phosphor or photoconductor layer. Extension of this concept to real time imaging--fluoroscopy--has had problems due to the very low noise required. A new design strategy for fluoroscopic active matrix flat panel detectors has therefore been investigated theoretically. In this approach, the active matrix has integrated thin-film amplifiers and readout electronics at each pixel and is called the amplified pixel detector array (APDA). Each amplified pixel consists of three thin-film transistors: an amplifier, a readout, and a reset TFT. The performance of the APDA approach compared to the conventional active matrix was investigated for two semiconductors commonly used to construct active matrix arrays--hydrogenated amorphous silicon and polycrystalline silicon. The results showed that with amplification close to the pixel, the noise from the external charge preamplifiers becomes insignificant. The thermal and flicker noise of the readout and the amplifying TFTs at the pixel become the dominant sources of noise. The magnitude of these noise sources is strongly dependent on the TFT geometry and its fabrication process. Both of these could be optimized to make the APDA active matrix operate at lower noise levels than is possible with the conventional approach. However, the APDA cannot be made to operate ideally (i.e., have noise limited only by the amount of radiation used) at the lowest exposure rate required in medical fluoroscopy.

Brightness field distributions of microlens arrays using micro molding.

PubMed

Cheng, Hsin-Chung; Huang, Chiung-Fang; Lin, Yi; Shen, Yung-Kang

2010-12-20

This study describes the brightness field distributions of microlens arrays fabricated by micro injection molding (μIM) and micro injection-compression molding (μICM). The process for fabricating microlens arrays used room-temperature imprint lithography, photoresist reflow, electroforming, μIM, μICM, and optical properties measurement. Analytical results indicate that the brightness field distribution of the molded microlens arrays generated by μICM is better than those made using μIM. Our results further demonstrate that mold temperature is the most important processing parameter for brightness field distribution of molded microlens arrays made by μIM or μICM.

A comparative study of n-channel low temperature poly-Si thin-film transistors with a body terminal or a lightly-doped-drain structure

NASA Astrophysics Data System (ADS)

Wu, Yanwen; Wang, Mingxiang; Wang, Huaisheng; Zhang, Dongli

2018-02-01

Hot-carrier (HC) induced degradation is a critical reliability issue of n-channel low temperature poly-Si thin-film transistors (TFTs) in TFT-based circuits. In this work, a kind of four-terminal TFT, which has an additional p+-doped lateral body terminal connecting to the floating channel, is systematically compared to conventional n-channel TFT and lightly-doped-drain (LDD) TFT. We demonstrate that the four-terminal TFT can provide similar advantages to that of the LDD TFT such as kink current suppression and DC HC degradation immunity, much superior immunity to the dynamic HC degradation, but without any tradeoffs in device performance and process complexity of the LDD TFT. It has high performance, as well as excellent reliability under both DC and AC conditions.

Effect of defect creation and migration on hump characteristics of a-InGaZnO thin film transistors under long-term drain bias stress with light illumination

NASA Astrophysics Data System (ADS)

Cho, Yong-Jung; Kim, Woo-Sic; Lee, Yeol-Hyeong; Park, Jeong Ki; Kim, Geon Tae; Kim, Ohyun

2018-06-01

We investigated the mechanism of formation of the hump that occurs in the current-voltage I-V characteristics of amorphous InGaZnO (a-IGZO) thin film transistors (TFTs) that are exposed to long-term drain bias stress under illumination. Transfer characteristics showed two-stage degradation under the stress. At the beginning of the stress, the I-V characteristics shifted in the negative direction with a degradation of subthreshold slope, but the hump phenomenon developed over time in the I-V characteristics. The development of the hump was related to creation of defects, especially ionized oxygen vacancies which act as shallow donor-like states near the conduction-band minimum in a-IGZO. To further investigate the hump phenomenon we measured a capacitance-voltage C-V curve and performed two-dimensional device simulation. Stretched-out C-V for the gate-to-drain capacitance and simulated electric field distribution which exhibited large electric field near the drain side of TFT indicated that VO2+ were generated near the drain side of TFT, but the hump was not induced when VO2+ only existed near the drain side. Therefore, the degradation behavior under DBITS occurred because VO2+ were created near the drain side, then were migrated to the source side of the TFT.

Enhancement of a-IGZO TFT Device Performance Using a Clean Interface Process via Etch-Stopper Nano-layers

NASA Astrophysics Data System (ADS)

Chung, Jae-Moon; Zhang, Xiaokun; Shang, Fei; Kim, Ji-Hoon; Wang, Xiao-Lin; Liu, Shuai; Yang, Baoguo; Xiang, Yong

2018-05-01

To overcome the technological and economic obstacles of amorphous indium-gallium-zinc-oxide (a-IGZO)-based display backplane for industrial production, a clean etch-stopper (CL-ES) process is developed to fabricate a-IGZO-based thin film transistor (TFT) with improved uniformity and reproducibility on 8.5th generation glass substrates (2200 mm × 2500 mm). Compared with a-IGZO-based TFT with back-channel-etched (BCE) structure, a newly formed ES nano-layer ( 100 nm) and a simultaneous etching of a-IGZO nano-layer (30 nm) and source-drain electrode layer are firstly introduced to a-IGZO-based TFT device with CL-ES structure to improve the uniformity and stability of device for large-area display. The saturation electron mobility of 8.05 cm2/V s and the V th uniformity of 0.72 V are realized on the a-IGZO-based TFT device with CL-ES structure. In the negative bias temperature illumination stress and positive bias thermal stress reliability testing under a ± 30 V bias for 3600 s, the measured V th shift of CL-ES-structured device significantly decreased to - 0.51 and + 1.94 V, which are much lower than that of BCE-structured device (- 3.88 V, + 5.58 V). The electrical performance of the a-IGZO-based TFT device with CL-ES structure implies that the economic transfer from a silicon-based TFT process to the metal oxide semiconductor-based process for LCD fabrication is highly feasible.

Optical residual stress measurement in TFT-LCD panels

NASA Astrophysics Data System (ADS)

Wang, Wei-Chung; Sung, Po-Chi

2017-06-01

The residual stress of the glass substrate might be one of causes to produce the non-uniform light distribution defect, i.e. Mura, in thin film transistor-liquid crystal display (TFT-LCD) panels. Glass is a birefringent material with very low birefringence. Furthermore, the thinner and thinner thickness request from the market makes the traditional photoelasticity almost impossible to measure the residual stresses produced in thin glass plates. Recently, a low-level stress measurement method called transmissivity extremities theory of photoelasticity (TEToP) was successfully developed to measure the residual stress in glass plate. Besides, to measure the stress of the glass plate in the TFT-LCD panel whose rear surface may has different kinds of coatings, an advanced reflection photoelasticity was also developed. In this paper, three commercially available glass plates with 0.33mm nominal thickness and three glass circular disks with different coatings were inspected to verify the feasibility of the TEToP and the advanced reflection photoelasticity, respectively.

Low temperature sputter-deposited ZnO films with enhanced Hall mobility using excimer laser post-processing

NASA Astrophysics Data System (ADS)

Tsakonas, C.; Kuznetsov, V. L.; Cranton, W. M.; Kalfagiannis, N.; Abusabee, K. M.; Koutsogeorgis, D. C.; Abeywickrama, N.; Edwards, P. P.

2017-12-01

We report the low temperature (T  <  70 °C) fabrication of ZnO thin films (~140 nm) with Hall mobility of up to 17.3 cm2 V-1 s-1 making them suitable for thin film transistor (TFT) applications. The films were deposited by rf magnetron sputtering at T  <  70 °C and subsequently laser processed in ambient temperature in order to modify the Hall mobility and carrier concentration. Medium-to-low energy laser radiation densities and a high number of pulses were used to avoid damaging the films. Laser annealing of the films after aging in the lab under 25%-35% relative humidity and at an average illuminance of 120 lux resulted in an overall higher mobility and relatively low carrier concentration in comparison to the non-aged films that were laser processed immediately after deposition. A maximum overall measured Hall mobility of 17.3 cm2 V-1 s-1 at a carrier density of 2.3  ×  1018 cm-3 was measured from a 1 GΩ as deposited and aged film after the laser treatment. We suggest that the aging of non-processed films reduces structural defects mainly at grain boundaries by air species chemisorption, with concomitant increase in thermal conductivity so that laser processing can have an enhancing effect. Such a processing combination can act synergistically and produce suitable active layers for TFT applications with low temperature processing requirements.

Micro-bridge defects: characterization and root cause analysis

NASA Astrophysics Data System (ADS)

Santoro, Gaetano; Van den Heuvel, Dieter; Braggin, Jennifer; Rosslee, Craig; Leray, Philippe J.; Cheng, Shaunee; Jehoul, Christiane; Schreutelkamp, Robert; Hillel, Noam

2010-03-01

Defect review of advanced lithography processes is becoming more and more challenging as feature sizes decrease. Previous studies using a defect review SEM on immersion lithography generated wafers have resulted in a defect classification scheme which, among others, includes a category for micro-bridges. Micro-bridges are small connections between two adjacent lines in photo-resist and are considered device killing defects. Micro-bridge rates also tend to increase as feature sizes decrease, making them even more important for the next technology nodes. Especially because micro-bridge defects can originate from different root causes, the need to further refine and split up the classification of this type of defect into sub groups may become a necessity. This paper focuses on finding the correlation of the different types of micro-bridge defects to a particular root cause based on a full characterization and root cause analysis of this class of defects, by using advanced SEM review capabilities like high quality imaging in very low FOV, Multi Perspective SEM Imaging (MPSI), tilted column and rotated stage (Tilt&Rotation) imaging and Focused Ion Beam (FIB) cross sectioning. Immersion lithography material has been mainly used to generate the set of data presented in this work even though, in the last part of the results, some EUV lithography data will be presented as part of the continuing effort to extend the micro-bridge defect characterization to the EUV technology on 40 nm technology node and beyond.

The art of war: beyond memory-one strategies in population games.

PubMed

Lee, Christopher; Harper, Marc; Fryer, Dashiell

2015-01-01

We show that the history of play in a population game contains exploitable information that can be successfully used by sophisticated strategies to defeat memory-one opponents, including zero determinant strategies. The history allows a player to label opponents by their strategies, enabling a player to determine the population distribution and to act differentially based on the opponent's strategy in each pairwise interaction. For the Prisoner's Dilemma, these advantages lead to the natural formation of cooperative coalitions among similarly behaving players and eventually to unilateral defection against opposing player types. We show analytically and empirically that optimal play in population games depends strongly on the population distribution. For example, the optimal strategy for a minority player type against a resident TFT population is ALLC, while for a majority player type the optimal strategy versus TFT players is ALLD. Such behaviors are not accessible to memory-one strategies. Drawing inspiration from Sun Tzu's the Art of War, we implemented a non-memory-one strategy for population games based on techniques from machine learning and statistical inference that can exploit the history of play in this manner. Via simulation we find that this strategy is essentially uninvadable and can successfully invade (significantly more likely than a neutral mutant) essentially all known memory-one strategies for the Prisoner's Dilemma, including ALLC (always cooperate), ALLD (always defect), tit-for-tat (TFT), win-stay-lose-shift (WSLS), and zero determinant (ZD) strategies, including extortionate and generous strategies.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taheri, M; Teslich, N; Lu, J P

An in situ method for studying the role of laser energy on the microstructural evolution of polycrystalline Si is presented. By monitoring both laser energy and microstructural evolution simultaneously in the dynamic transmission electron microscope, information on grain size and defect concentration can be correlated directly with processing conditions. This proof of principle study provides fundamental scientific information on the crystallization process that has technological importance for the development of thin film transistors. In conclusion, we successfully developed a method for studying UV laser processing of Si films in situ on nanosecond time scales, with ultimate implications for TFT applicationmore » improvements. In addition to grain size distribution as a function of laser energy density, we found that grain size scaled with laser energy in general. We showed that nanosecond time resolution allowed us to see the nucleation and growth front during processing, which will help further the understanding of microstructural evolution of poly-Si films for electronic applications. Future studies, coupled with high resolution TEM, will be performed to study grain boundary migration, intergranular defects, and grain size distribution with respect to laser energy and adsorption depth.« less

Manufacturing PDMS micro lens array using spin coating under a multiphase system

NASA Astrophysics Data System (ADS)

Sun, Rongrong; Yang, Hanry; Rock, D. Mitchell; Danaei, Roozbeh; Panat, Rahul; Kessler, Michael R.; Li, Lei

2017-05-01

The development of micro lens arrays has garnered much interest due to increased demand of miniaturized systems. Traditional methods for manufacturing micro lens arrays have several shortcomings. For example, they require expensive facilities and long lead time, and traditional lens materials (i.e. glass) are typically heavy, costly and difficult to manufacture. In this paper, we explore a method for manufacturing a polydimethylsiloxane (PDMS) micro lens array using a simple spin coating technique. The micro lens array, formed under an interfacial tension dominated system, and the influence of material properties and process parameters on the fabricated lens shape are examined. The lenses fabricated using this method show comparable optical properties—including surface finish and image quality—with a reduced cost and manufacturing lead time.

Enhancement of a-IGZO TFT Device Performance Using a Clean Interface Process via Etch-Stopper Nano-layers.

PubMed

Chung, Jae-Moon; Zhang, Xiaokun; Shang, Fei; Kim, Ji-Hoon; Wang, Xiao-Lin; Liu, Shuai; Yang, Baoguo; Xiang, Yong

2018-05-29

To overcome the technological and economic obstacles of amorphous indium-gallium-zinc-oxide (a-IGZO)-based display backplane for industrial production, a clean etch-stopper (CL-ES) process is developed to fabricate a-IGZO-based thin film transistor (TFT) with improved uniformity and reproducibility on 8.5th generation glass substrates (2200 mm × 2500 mm). Compared with a-IGZO-based TFT with back-channel-etched (BCE) structure, a newly formed ES nano-layer (~ 100 nm) and a simultaneous etching of a-IGZO nano-layer (30 nm) and source-drain electrode layer are firstly introduced to a-IGZO-based TFT device with CL-ES structure to improve the uniformity and stability of device for large-area display. The saturation electron mobility of 8.05 cm 2 /V s and the V th uniformity of 0.72 V are realized on the a-IGZO-based TFT device with CL-ES structure. In the negative bias temperature illumination stress and positive bias thermal stress reliability testing under a ± 30 V bias for 3600 s, the measured V th shift of CL-ES-structured device significantly decreased to - 0.51 and + 1.94 V, which are much lower than that of BCE-structured device (- 3.88 V, + 5.58 V). The electrical performance of the a-IGZO-based TFT device with CL-ES structure implies that the economic transfer from a silicon-based TFT process to the metal oxide semiconductor-based process for LCD fabrication is highly feasible.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crowder, M.A.; Sposili, R.S.; Cho, H.S.

Nonhydrogenated, n-channel, low-temperature-processed, single-crystal Si thin-film transistors (TFT`s) have been fabricated on Si thin films prepared via sequential lateral solidification (SLS). The device characteristics of the resulting SLS TFT`s exhibit properties and a level of performance that are superior to polycrystalline Si-based TFT`s and are comparable to similar devices fabricated on silicon-on-insulator (SOI) substrates or bulk-Si wafers. The authors attribute these high-performance device characteristics to the absence of high-angle grain-boundaries within the active channel portion of the TFT`s.

Isotropic differential phase contrast microscopy for quantitative phase bio-imaging.

PubMed

Chen, Hsi-Hsun; Lin, Yu-Zi; Luo, Yuan

2018-05-16

Quantitative phase imaging (QPI) has been investigated to retrieve optical phase information of an object and applied to biological microscopy and related medical studies. In recent examples, differential phase contrast (DPC) microscopy can recover phase image of thin sample under multi-axis intensity measurements in wide-field scheme. Unlike conventional DPC, based on theoretical approach under partially coherent condition, we propose a new method to achieve isotropic differential phase contrast (iDPC) with high accuracy and stability for phase recovery in simple and high-speed fashion. The iDPC is simply implemented with a partially coherent microscopy and a programmable thin-film transistor (TFT) shield to digitally modulate structured illumination patterns for QPI. In this article, simulation results show consistency of our theoretical approach for iDPC under partial coherence. In addition, we further demonstrate experiments of quantitative phase images of a standard micro-lens array, as well as label-free live human cell samples. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A 128×96 Pixel Stack-Type Color Image Sensor: Stack of Individual Blue-, Green-, and Red-Sensitive Organic Photoconductive Films Integrated with a ZnO Thin Film Transistor Readout Circuit

NASA Astrophysics Data System (ADS)

Seo, Hokuto; Aihara, Satoshi; Watabe, Toshihisa; Ohtake, Hiroshi; Sakai, Toshikatsu; Kubota, Misao; Egami, Norifumi; Hiramatsu, Takahiro; Matsuda, Tokiyoshi; Furuta, Mamoru; Hirao, Takashi

2011-02-01

A color image was produced by a vertically stacked image sensor with blue (B)-, green (G)-, and red (R)-sensitive organic photoconductive films, each having a thin-film transistor (TFT) array that uses a zinc oxide (ZnO) channel to read out the signal generated in each organic film. The number of the pixels of the fabricated image sensor is 128×96 for each color, and the pixel size is 100×100 µm2. The current on/off ratio of the ZnO TFT is over 106, and the B-, G-, and R-sensitive organic photoconductive films show excellent wavelength selectivity. The stacked image sensor can produce a color image at 10 frames per second with a resolution corresponding to the pixel number. This result clearly shows that color separation is achieved without using any conventional color separation optical system such as a color filter array or a prism.

A Novel Machine Vision System for the Inspection of Micro-Spray Nozzle

PubMed Central

Huang, Kuo-Yi; Ye, Yu-Ting

2015-01-01

In this study, we present an application of neural network and image processing techniques for detecting the defects of an internal micro-spray nozzle. The defect regions were segmented by Canny edge detection, a randomized algorithm for detecting circles and a circle inspection (CI) algorithm. The gray level co-occurrence matrix (GLCM) was further used to evaluate the texture features of the segmented region. These texture features (contrast, entropy, energy), color features (mean and variance of gray level) and geometric features (distance variance, mean diameter and diameter ratio) were used in the classification procedures. A back-propagation neural network classifier was employed to detect the defects of micro-spray nozzles. The methodology presented herein effectively works for detecting micro-spray nozzle defects to an accuracy of 90.71%. PMID:26131678

A Novel Machine Vision System for the Inspection of Micro-Spray Nozzle.

PubMed

Huang, Kuo-Yi; Ye, Yu-Ting

2015-06-29

In this study, we present an application of neural network and image processing techniques for detecting the defects of an internal micro-spray nozzle. The defect regions were segmented by Canny edge detection, a randomized algorithm for detecting circles and a circle inspection (CI) algorithm. The gray level co-occurrence matrix (GLCM) was further used to evaluate the texture features of the segmented region. These texture features (contrast, entropy, energy), color features (mean and variance of gray level) and geometric features (distance variance, mean diameter and diameter ratio) were used in the classification procedures. A back-propagation neural network classifier was employed to detect the defects of micro-spray nozzles. The methodology presented herein effectively works for detecting micro-spray nozzle defects to an accuracy of 90.71%.

Healing of damaged metal by a pulsed high-energy electromagnetic field

NASA Astrophysics Data System (ADS)

Kukudzhanov, K. V.; Levitin, A. L.

2018-04-01

The processes of defect (intergranular micro-cracks) transformation are investigated for metal samples in a high-energy short-pulsed electromagnetic field. This investigation is based on a numerical coupled model of the impact of high-energy electromagnetic field on the pre-damaged thermal elastic-plastic material with defects. The model takes into account the melting and evaporation of the metal and the dependence of its physical and mechanical properties on the temperature. The system of equations is solved numerically by finite element method with an adaptive mesh using the arbitrary Euler–Lagrange method. The calculations show that the welding of the crack and the healing of micro-defects under treatment by short pulses of the current takes place. For the macroscopic description of the healing process, the healing and damage parameters of the material are introduced. The healing of micro-cracks improves the material healing parameter and reduces its damage. The micro-crack shapes practically do not affect the time-dependence of the healing and damage under the treatment by the current pulses. These changes are affected only by the value of the initial damage of the material and the initial length of the micro-crack. The time-dependence of the healing and the damage is practically the same for all different shapes of micro-defects, provided that the initial lengths of micro-cracks and the initial damages are the same for these different shapes of defects.

Zinc Oxide Thin-Film Transistors

NASA Astrophysics Data System (ADS)

Fortunato, E.; Barquinha, P.; Pimentel, A.; Gonçalves, A.; Marques, A.; Pereira, L.; Martins, R.

ZnO thin film transistors (ZnO-TFT) have been fabricated by rf magnetron sputtering at room temperature with a bottom-gate configuration. The ZnO-TFT operates in the enhancement mode with a threshold voltage of 21 V, a field effect mobility of 20 cm2/Vs, a gate voltage swing of 1.24 V/decade and an on/off ratio of 2×105. The ZnO-TFT present an average optical transmission (including the glass substrate) of 80 % in the visible part of the spectrum. The combination of transparency, high channel mobility and room temperature processing makes the ZnO-TFT a very promising low cost optoelectronic device for the next generation of invisible and flexible electronics. Moreover, the processing technology used to fabricate this device is relatively simple and it is compatible with inexpensive plastic/flexible substrate technology.

Reliable 6 PEP LTPS device for AMOLED's

NASA Astrophysics Data System (ADS)

Chou, Cheng-Wei; Wang, Pei-Yun; Hu, Chin-Wei; Chang, York; Chuang, Ching-Sang; Lin, Yusin

2013-09-01

This study presents a TFT structure which has less photo process and higher cost competitiveness in AMOLED display markets. A novel LTPS based 6 masks TFT structure for bottom emission AMOLED display is demonstrated in this paper. High field effect mobility (PMOS < 80 cm2/Vs ) and high reliability (PBTS △Vth< 0.02V @ 50oC VG=15V 10ks) was accomplished without the high temperature and rapid thermal annealing (RTA) activation process. Furthermore, a 14-inch AMOLED TV was achieved on the proposed 6-pep TFT backplane using the Gen. 3.5 mass production factory.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Po-Tsun; Shieh, Han-Ping; Chou, Yi-Teh

This work presents the electrical characteristics of the nitrogenated amorphous InGaZnO thin film transistor (a-IGZO:N TFT). The a-IGZO:N film acting as a channel layer of a thin film transistor (TFT) device was prepared by dc reactive sputter with a nitrogen and argon gas mixture at room temperature. Experimental results show that the in situ nitrogen incorporation to IGZO film can properly adjust the threshold voltage and enhance the ambient stability of a TFT device. Furthermore, the a-IGZO:N TFT has a 44% increase in the carrier mobility and electrical reliability and uniformity also progress obviously while comparing with those not implementingmore » a nitrogen doping process.« less

Extension of optical lithography by mask-litho integration with computational lithography

NASA Astrophysics Data System (ADS)

Takigawa, T.; Gronlund, K.; Wiley, J.

2010-05-01

Wafer lithography process windows can be enlarged by using source mask co-optimization (SMO). Recently, SMO including freeform wafer scanner illumination sources has been developed. Freeform sources are generated by a programmable illumination system using a micro-mirror array or by custom Diffractive Optical Elements (DOE). The combination of freeform sources and complex masks generated by SMO show increased wafer lithography process window and reduced MEEF. Full-chip mask optimization using source optimized by SMO can generate complex masks with small variable feature size sub-resolution assist features (SRAF). These complex masks create challenges for accurate mask pattern writing and low false-defect inspection. The accuracy of the small variable-sized mask SRAF patterns is degraded by short range mask process proximity effects. To address the accuracy needed for these complex masks, we developed a highly accurate mask process correction (MPC) capability. It is also difficult to achieve low false-defect inspections of complex masks with conventional mask defect inspection systems. A printability check system, Mask Lithography Manufacturability Check (M-LMC), is developed and integrated with 199-nm high NA inspection system, NPI. M-LMC successfully identifies printable defects from all of the masses of raw defect images collected during the inspection of a complex mask. Long range mask CD uniformity errors are compensated by scanner dose control. A mask CD uniformity error map obtained by mask metrology system is used as input data to the scanner. Using this method, wafer CD uniformity is improved. As reviewed above, mask-litho integration technology with computational lithography is becoming increasingly important.

Optimal Micro-Jet Flow Control for Compact Air Vehicle Inlets

NASA Technical Reports Server (NTRS)

Anderson, Bernhard H.; Miller, Daniel N.; Addington, Gregory A.; Agrell, Johan

2004-01-01

The purpose of this study on micro-jet secondary flow control is to demonstrate the viability and economy of Response Surface Methodology (RSM) to optimally design micro-jet secondary flow control arrays, and to establish that the aeromechanical effects of engine face distortion can also be included in the design and optimization process. These statistical design concepts were used to investigate the design characteristics of "low mass" micro-jet array designs. The term "low mass" micro-jet may refers to fluidic jets with total (integrated) mass flow ratios between 0.10 and 1.0 percent of the engine face mass flow. Therefore, this report examines optimal micro-jet array designs for compact inlets through a Response Surface Methodology.

Quantification of micro-CT images of textile reinforcements

NASA Astrophysics Data System (ADS)

Straumit, Ilya; Lomov, Stepan V.; Wevers, Martine

2017-10-01

VoxTex software (KU Leuven) employs 3D image processing, which use the local directionality information, retrieved using analysis of local structure tensor. The processing results in a voxel 3D array, with each voxel carrying information on (1) material type (matrix; yarn/ply, with identification of the yarn/ply in the reinforcement architecture; void) and (2) fibre direction for fibrous yarns/plies. The knowledge of the material phase volume and known characterisation of the textile structure allows assigning to the voxels (3) fibre volume fraction. This basic voxel model can be further used for different type of the material analysis: Internal geometry and characterisation of defects; permeability; micromechanics; mesoFE voxel models. Apart from the voxel based analysis, approaches to reconstruction of the yarn paths are presented.

Hydrophilic/hydrophobic surface modification impact on colloid lithography: Schottky-like defects, dislocation, and ideal distribution

NASA Astrophysics Data System (ADS)

Burtsev, Vasilii; Marchuk, Valentina; Kugaevskiy, Artem; Guselnikova, Olga; Elashnikov, Roman; Miliutina, Elena; Postnikov, Pavel; Svorcik, Vaclav; Lyutakov, Oleksiy

2018-03-01

Nano-spheres lithography is actually considered as a powerful tool to manufacture various periodic structures with a wide potential in the field of nano- and micro-fabrication. However, during self-assembling of colloid microspheres, various defects and mismatches can appear. In this work the size and quality of single-domains of closed-packed polystyrene (PS), grown up on thin Au layers modified by hydrophilic or hydrophobic functional groups via diazonium chemistry was studied. The effects of the surface modification on the quality and single-domain size of polystyrene (PS) microspheres array were investigated and discussed. Modified surfaces were characterized using the AFM and wettability tests. PS colloidal suspension was deposited using the drop evaporation method. Resulted PS microspheres array was characterized using the SEM, AFM and confocal microscopy technique.

Micromirror array nanostructures for anticounterfeiting applications

NASA Astrophysics Data System (ADS)

Lee, Robert A.

2004-06-01

The optical characteristics of pixellated passive micro mirror arrays are derived and applied in the context of their use as reflective optically variable device (OVD) nanostructures for the protection of documents from counterfeiting. The traditional design variables of foil based diffractive OVDs are shown to be able to be mapped to a corresponding set of design parameters for reflective optical micro mirror array (OMMA) devices. The greatly increased depth characteristics of micro mirror array OVDs provides an opportunity for directly printing the OVD microstructure onto the security document in-line with the normal printing process. The micro mirror array OVD architecture therefore eliminates the need for hot stamping foil as the carrier of the OVD information, thereby reducing costs. The origination of micro mirror array devices via a palette based data format and a combination electron beam lithography and photolithography techniques is discussed via an artwork example and experimental tests. Finally the application of the technology to the design of a generic class of devices which have the interesting property of allowing for both application and customer specific OVD image encoding and data encoding at the end user stage of production is described. Because of the end user nature of the image and data encoding process these devices are particularly well suited to ID document applications and for this reason we refer this new OVD concept as biometric OVD technology.

Aluminum-based one- and two-dimensional micro fin array structures: high-throughput fabrication and heat transfer testing

NASA Astrophysics Data System (ADS)

Primeaux, Philip A.; Zhang, Bin; Zhang, Xiaoman; Miller, Jacob; Meng, W. J.; KC, Pratik; Moore, Arden L.

2017-02-01

Microscale fin array structures were replicated onto surfaces of aluminum 1100 and aluminum 6061 alloy (Al1100/Al6061) sheet metals through room-temperature instrumented roll molding. Aluminum-based micro fin arrays were replicated at room temperature, and the fabrication process is one with high throughput and low cost. One-dimensional (1D) micro fin arrays were made through one-pass rolling, while two-dimensional (2D) micro fin arrays were made by sequential 90° cross rolling with the same roller sleeve. For roll molding of 1D micro fins, fin heights greater than 600 µm were achieved and were shown to be proportional to the normal load force per feature width. At a given normal load force, the fin height was further shown to scale inversely with the hardness of the sheet metal. For sequential 90° cross rolling, morphologies of roll molded 2D micro fin arrays were examined, which provided clues to understand how plastic deformation occurred under cross rolling conditions. A series of pool boiling experiments on low profile Al micro fin array structures were performed within Novec 7100, a widely used commercial dielectric coolant. Results for both horizontal and vertical surface orientations show that roll molded Al micro fin arrays can increase heat flux at fixed surface temperature as compared to un-patterned Al sheet. The present results further suggest that many factors beyond just increased surface area can influence heat transfer performance, including surface finish and the important multiphase transport mechanisms in and around the fin geometry. These factors must also be considered when designing and optimizing micro fin array structures for heat transfer applications.

Laser direct-write and crystallization of FeSi II micro-dot array for NIR light-emitting device application

NASA Astrophysics Data System (ADS)

Narazaki, Aiko; Kurosaki, Ryozo; Sato, Tadatake; Kawaguchi, Yoshizo; Niino, Hiroyuki

2007-02-01

We printed FeSi II micro-dot array on various kinds of substrates utilizing laser-induced forward transfer (LIFT). An amorphous FeSi II was deposited by sputtering on a transparent plate as a source film. A single KrF excimer laser pulse through a mask-projection system was imaged with a small micrometer-sized grid pattern onto a film/plate interface, resulting in the deposition of FeSi II micro-dot array on a facing substrate with a high number density of 10 4 mm -2. FeSi II in the β crystalline phase is a promising eco-friendly semiconductor because of NIR electroluminescence used for optical networking as well as abundant components reserve on the earth and non-toxicity. However, the β-FeSi II film fabrication generally required high-temperature multi-processes which hamper its integration and performance reproducibility. Using the LIFT of micro-dot array, we succeeded in room-temperature preparation of β-FeSi II. Micro-Raman spectroscopy confirmed the β crystalline phase in the micro-dots deposited on an unheated silica glass substrate. Thus, the LIFT is useful for integrating functional micro-dot array accompanied by the crystallization at lower temperatures.

Instabilities of Damage and Surface Degradation Mechanisms in Brittle Material Structural Systems

DTIC Science & Technology

1992-03-15

I INTRODUCTION AND SCOPE 1.1 General Brittle materials such as rock and concrete contain a multitude of defects in the form of micro-voids and/or...micro-cracks even before any external load is applied. The term "structure" is associated with such defects . During a loading- unloading process, these...voids/cracks may undergo irreversible growth and new ones may nucleate. The ultimate coalescence of such defects may result in macro- crack initiation

Optimal Micro-Vane Flow Control for Compact Air Vehicle Inlets

NASA Technical Reports Server (NTRS)

Anderson, Bernhard H.; Miller, Daniel N.; Addington, Gregory A.; Agrell, Johan

2004-01-01

The purpose of this study on micro-vane secondary flow control is to demonstrate the viability and economy of Response Surface Methodology (RSM) to optimally design micro-vane secondary flow control arrays, and to establish that the aeromechanical effects of engine face distortion can also be included in the design and optimization process. These statistical design concepts were used to investigate the design characteristics of "low unit strength" micro-effector arrays. "Low unit strength" micro-effectors are micro-vanes set at very low angles-of-incidence with very long chord lengths. They were designed to influence the near wall inlet flow over an extended streamwise distance, and their advantage lies in low total pressure loss and high effectiveness in managing engine face distortion. Therefore, this report examines optimal micro-vane secondary flow control array designs for compact inlets through a Response Surface Methodology.

High performance MoS2 TFT using graphene contact first process

NASA Astrophysics Data System (ADS)

Chang Chien, Chih-Shiang; Chang, Hsun-Ming; Lee, Wei-Ta; Tang, Ming-Ru; Wu, Chao-Hsin; Lee, Si-Chen

2017-08-01

An ohmic contact of graphene/MoS2 heterostructure is determined by using ultraviolet photoelectron spectroscopy (UPS). Since graphene shows a great potential to replace metal contact, a direct comparison of Cr/Au contact and graphene contact on the MoS2 thin film transistor (TFT) is made. Different from metal contacts, the work function of graphene can be modulated. As a result, the subthreshold swing can be improved. And when Vg

Stable and High-Performance Flexible ZnO Thin-Film Transistors by Atomic Layer Deposition.

PubMed

Lin, Yuan-Yu; Hsu, Che-Chen; Tseng, Ming-Hung; Shyue, Jing-Jong; Tsai, Feng-Yu

2015-10-14

Passivation is a challenging issue for the oxide thin-film transistor (TFT) technologies because it requires prolonged high-temperature annealing treatments to remedy defects produced in the process, which greatly limits its manufacturability as well as its compatibility with temperature-sensitive materials such as flexible plastic substrates. This study investigates the defect-formation mechanisms incurred by atomic layer deposition (ALD) passivation processes on ZnO TFTs, based on which we demonstrate for the first time degradation-free passivation of ZnO TFTs by a TiO2/Al2O3 nanolaminated (TAO) film deposited by a low-temperature (110 °C) ALD process. By combining the TAO passivation film with ALD dielectric and channel layers into an integrated low-temperature ALD process, we successfully fabricate flexible ZnO TFTs on plastics. Thanks to the exceptional gas-barrier property of the TAO film (water vapor transmission rate (WVTR)<10(-6) g m(-2) day(-1)) as well as the defect-free nature of the ALD dielectric and ZnO channel layers, the TFTs exhibit excellent device performance with high stability and flexibility: field-effect mobility>20 cm2 V(-1) s(-1), subthreshold swing<0.4 V decade(-1) after extended bias-stressing (>10,000 s), air-storage (>1200 h), and bending (1.3 cm radius for 1000 times).

Advanced Micro-Polycrystalline Silicon Films Formed by Blue-Multi-Laser-Diode Annealing

NASA Astrophysics Data System (ADS)

Noguchi, Takashi; Chen, Yi; Miyahira, Tomoyuki; de Dieu Mugiraneza, Jean; Ogino, Yoshiaki; Iida, Yasuhiro; Sahota, Eiji; Terao, Motoyasu

2010-03-01

Semiconductor blue-multi-laser-diode annealing (BLDA) for amorphous Si film was performed to obtain a film containing uniform polycrystalline silicon (poly-Si) grains as a low temperature poly-Si (LTPS) process used for thin-film transistor (TFT). By adopting continuous wave (CW) mode at the 445 nm wavelength of the BLDA system, the light beam is efficiently absorbed into the thin amorphous silicon film of 50 nm thickness and can be crystallized stably. By adjusting simply the laser power below 6 W with controlled beam shape, the isotropic Si grains from uniform micro-grains to arbitral grain size of polycrystalline phase can be obtained with reproducible by fixing the scan speed at 500 mm/s. As a result of analysis using electron microscopy and atomic force microscopy (AFM), uniform distributed micro-poly-Si grains of smooth surface were observed at a power condition below 5 W and the preferred crystal orientation of (111) face was confirmed. As arbitral grain size can be obtained stably and reproducibly merely by controlling the laser power, BLDA is promising as a next-generation LTPS process for AM OLED panel including a system on glass (SoG).

Application of Ultrasonic Phased Array Technology to the Detection of Defect in Composite Stiffened-structures

NASA Astrophysics Data System (ADS)

Zhou, Yuan-Qi; Zhan, Li-Hua

2016-05-01

Composite stiffened-structure consists of the skin and stringer has been widely used in aircraft fuselage and wings. The main purpose of the article is to detect the composite material reinforced structure accurately and explore the relationship between defect formation and structural elements or curing process. Based on ultrasonic phased array inspection technology, the regularity of defects in the manufacture of composite materials are obtained, the correlation model between actual defects and nondestructive testing are established. The article find that the forming quality of deltoid area in T-stiffened structure is obviously improved by pre-curing, the defects of hat-stiffened structure are affected by the mandrel. The results show that the ultrasonic phased array inspection technology can be an effectively way for the detection of composite stiffened-structures, which become an important means to control the defects of composite and improve the quality of the product.

Successful demonstration of a comprehensive lithography defect monitoring strategy

NASA Astrophysics Data System (ADS)

Peterson, Ingrid B.; Breaux, Louis H.; Cross, Andrew; von den Hoff, Michael

2003-07-01

This paper describes the validation of the methodology, the model and the impact of an optimized Lithography Defect Monitoring Strategy at two different semiconductor manufacturing factories. The lithography defect inspection optimization was implemented for the Gate Module at both factories running 0.13-0.15μm technologies on 200mm wafers, one running microprocessor and the other memory devices. As minimum dimensions and process windows decrease in the lithography area, new technologies and technological advances with resists and resist systems are being implemented to meet the demands. Along with these new technological advances in the lithography area comes potentially unforeseen defect issues. The latest lithography processes involve new resists in extremely thin, uniform films, exposing the films under conditions of highly optimized focus and illumination, and finally removing the resist completely and cleanly. The lithography cell is defined as the cluster of process equipment that accomplishes the coating process (surface prep, resist spin, edge-bead removal and soft bake), the alignment and exposure, and the developing process (post-exposure bake, develop, rinse) of the resist. Often the resist spinning process involves multiple materials such as BARC (bottom ARC) and / or TARC (top ARC) materials in addition to the resist itself. The introduction of these new materials with the multiple materials interfaces and the tightness of the process windows leads to an increased variety of defect mechanisms in the lithography area. Defect management in the lithography area has become critical to successful product introduction and yield ramp. The semiconductor process itself contributes the largest number and variety of defects, and a significant portion of the total defects originate within the lithography cell. From a defect management perspective, the lithography cell has some unique characteristics. First, defects in the lithography process module have the widest range of sizes, from full-wafer to suboptical, and with the largest variety of characteristics. Some of these defects fall into the categories of coating problems, focus and exposure defects, developer defects, edge-bead removal problems, contamination and scratches usually defined as lithography macro defects as shown in Figure 1. Others fall into the category of lithography micro defects, Figure 2. They are characterized as having low topography such as stains, developer spots, satellites, are very small such as micro-bridging, partial micro-bridging, micro-bubbles, CD variation and single isolated missing or deformed contacts or vias. Lithography is the only area of the fab besides CMP in which defect excursions can be corrected by reworking the wafers. The opportunity to fix defect problems without scrapping wafers is best served by a defect inspection strategy that captures the full range of all relevant defect types with a proper balance between the costs of monitoring and inspection and the potential cost of yield loss. In the previous paper [1] it was shown that a combination of macro inspection and high numerical aperture (NA) brightfield imaging inspection technology is best suited for the application in the case of the idealized fab modeled. In this paper we will report on the successful efforts in implementing and validating the lithography defect monitoring strategy at two existing 200 mm factories running 0.15 μm and 0.13 μm design rules.

Research on the Micro Sheet Stamping Process Using Plasticine as Soft Punch

PubMed Central

Wang, Xiao; Zhang, Di; Gu, Chunxing; Shen, Zongbao; Liu, Huixia

2014-01-01

Plasticine is widely used in the analysis of metal forming processes, due to its excellent material flow ability. In this study, plasticine is used as the soft punch to fabricate array micro-channels on metal sheet in the micro sheet stamping process. This is because plasticine can produce a large material flow after being subjected to force and through the material flow, the plasticine can cause the sheet to fill into the micro-channels of the rigid die, leading to the generation of micro-channels in the sheet. The distribution of array micro-channels was investigated as well as the influence of load forces on the sheet deformations. It was found that the depth of micro-channels increases as the load force increases. When the load force reaches a certain level, a crack can be observed. The micro sheet stamping process was also investigated by the method of numerical simulation. The obtained experimental and numerical results for the stamping process showed that they were in good agreement. Additionally, from the simulation results, it can be seen that the corner region of the micro-channel-shape work piece has a risk to crack due to the existence of maximum von Mises stress and significant thinning. PMID:28788668

Low-Temperature UV-Assisted Fabrication of Metal Oxide Thin Film Transistor

NASA Astrophysics Data System (ADS)

Zhu, Shuanglin

Solution processed metal oxide semiconductors have attracted intensive attention in the last several decades and have emerged as a promising candidate for the application of thin film transistor (TFT) due to their nature of transparency, flexibility, high mobility, simple processing technique and potential low manufacturing cost. However, metal oxide thin film fabricated by solution process usually requires a high temperature (over 300 °C), which is above the glass transition temperature of some conventional polymer substrates. In order to fabricate the flexible electronic device on polymer substrates, it is necessary to find a facile approach to lower the fabrication temperature and minimize defects in metal oxide thin film. In this thesis, the electrical properties dependency on temperature is discussed and an UV-assisted annealing method incorporating Deep ultraviolet (DUV)-decomposable additives is demonstrated, which can effectively improve electrical properties solution processed metal oxide semiconductors processed at temperature as low as 220 °C. By studying a widely used indium oxide (In2O3) TFT as a model system, it is worth noted that compared with the sample without UV treatment, the linear mobility and saturation mobility of UV-annealing sample are improved by 56% and 40% respectively. Meanwhile, the subthreshold swing is decreased by 32%, indicating UV-treated device could turn on and off more efficiently. In addition to pure In2O3 film, the similar phenomena have also been observed in indium oxide based Indium-Gallium-Zinc Oxide (IGZO) system. These finding presented in this thesis suggest that the UV assisted annealing process open a new route to fabricate high performance metal oxide semiconductors under low temperatures.

Review of the potential of a wireless MEMS and TFT microsystems for the measurement of pressure in the GI tract.

PubMed

Arshak, A; Arshak, K; Waldron, D; Morris, D; Korostynska, O; Jafer, E; Lyons, G

2005-06-01

Telemetry capsules have existed since the 1950s and were used to measure temperature, pH or pressure inside the gastrointestinal (GI) tract. It was hoped that these capsules would replace invasive techniques in the diagnosis of function disorders in the GI tract. However, problems such as signal loss and uncertainty of the pills position limited their use in a clinical setting. In this paper, a review of the capabilities of MicroElectroMechanical Systems (MEMS) and thick film technology (TFT) for the fabrication of a wireless pressure sensing microsystem is presented. The circuit requirements and methods of data transfer are examined. The available fabrication methods for MEMS sensors are also discussed and examples of wireless sensors are given. Finally the limitations of each technology are examined.

Ontology-based, Tissue MicroArray oriented, image centered tissue bank

PubMed Central

Viti, Federica; Merelli, Ivan; Caprera, Andrea; Lazzari, Barbara; Stella, Alessandra; Milanesi, Luciano

2008-01-01

Background Tissue MicroArray technique is becoming increasingly important in pathology for the validation of experimental data from transcriptomic analysis. This approach produces many images which need to be properly managed, if possible with an infrastructure able to support tissue sharing between institutes. Moreover, the available frameworks oriented to Tissue MicroArray provide good storage for clinical patient, sample treatment and block construction information, but their utility is limited by the lack of data integration with biomolecular information. Results In this work we propose a Tissue MicroArray web oriented system to support researchers in managing bio-samples and, through the use of ontologies, enables tissue sharing aimed at the design of Tissue MicroArray experiments and results evaluation. Indeed, our system provides ontological description both for pre-analysis tissue images and for post-process analysis image results, which is crucial for information exchange. Moreover, working on well-defined terms it is then possible to query web resources for literature articles to integrate both pathology and bioinformatics data. Conclusions Using this system, users associate an ontology-based description to each image uploaded into the database and also integrate results with the ontological description of biosequences identified in every tissue. Moreover, it is possible to integrate the ontological description provided by the user with a full compliant gene ontology definition, enabling statistical studies about correlation between the analyzed pathology and the most commonly related biological processes. PMID:18460177

Enhanced ZnO Thin-Film Transistor Performance Using Bilayer Gate Dielectrics.

PubMed

Alshammari, Fwzah H; Nayak, Pradipta K; Wang, Zhenwei; Alshareef, Husam N

2016-09-07

We report ZnO TFTs using Al2O3/Ta2O5 bilayer gate dielectrics grown by atomic layer deposition. The saturation mobility of single layer Ta2O5 dielectric TFT was 0.1 cm(2) V(-1) s(-1), but increased to 13.3 cm(2) V(-1) s(-1) using Al2O3/Ta2O5 bilayer dielectric with significantly lower leakage current and hysteresis. We show that point defects present in ZnO film, particularly VZn, are the main reason for the poor TFT performance with single layer dielectric, although interfacial roughness scattering effects cannot be ruled out. Our approach combines the high dielectric constant of Ta2O5 and the excellent Al2O3/ZnO interface quality, resulting in improved device performance.

A fully roll-to-roll gravure-printed carbon nanotube-based active matrix for multi-touch sensors

PubMed Central

Lee, Wookyu; Koo, Hyunmo; Sun, Junfeng; Noh, Jinsoo; Kwon, Kye-Si; Yeom, Chiseon; Choi, Younchang; Chen, Kevin; Javey, Ali; Cho, Gyoujin

2015-01-01

Roll-to-roll (R2R) printing has been pursued as a commercially viable high-throughput technology to manufacture flexible, disposable, and inexpensive printed electronic devices. However, in recent years, pessimism has prevailed because of the barriers faced when attempting to fabricate and integrate thin film transistors (TFTs) using an R2R printing method. In this paper, we report 20 × 20 active matrices (AMs) based on single-walled carbon nanotubes (SWCNTs) with a resolution of 9.3 points per inch (ppi) resolution, obtained using a fully R2R gravure printing process. By using SWCNTs as the semiconducting layer and poly(ethylene terephthalate) (PET) as the substrate, we have obtained a device yield above 98%, and extracted the key scalability factors required for a feasible R2R gravure manufacturing process. Multi-touch sensor arrays were achieved by laminating a pressure sensitive rubber onto the SWCNT-TFT AM. This R2R gravure printing system overcomes the barriers associated with the registration accuracy of printing each layer and the variation of the threshold voltage (Vth). By overcoming these barriers, the R2R gravure printing method can be viable as an advanced manufacturing technology, thus enabling the high-throughput production of flexible, disposable, and human-interactive cutting-edge electronic devices based on SWCNT-TFT AMs. PMID:26635237

Replication fidelity improvement of PMMA microlens array based on weight evaluation and optimization

NASA Astrophysics Data System (ADS)

Jiang, Bing-yan; Shen, Long-jiang; Peng, Hua-jiang; Yin, Xiang-lin

2007-12-01

High replication fidelity is a prerequisite of high quality plastic microlens array in injection molding. But, there's not an economical and practical method to evaluate and improve the replication fidelity until now. Based on part weight evaluation and optimization, this paper presents a new method of replication fidelity improvement. Firstly, a simplified analysis model of PMMA micro columns arrays (5×16) with 200μm diameter was set up. And then, Flow (3D) module of Moldflow MPI6.0 based on Navier-Stokes equations was used to calculate the weight of the micro columns arrays in injection molding. The effects of processing parameters (melt temperature, mold temperature, injection time, packing pressure and packing time) on the part weight were investigated in the simulations. The simulation results showed that the mold temperature and the injection time have important effects on the filling of micro columns; the optimal mold temperature and injection time for better replication fidelity could be determined by the curves of mold temperature vs part weight and injection time vs part weight. At last, the effects of processing parameters on part weight of micro columns array were studied experimentally. The experimental results showed that the increase of melt temperature and mold temperature can make the packing pressure transfer to micro cavity more effectively through runner system, and increase the part weight. From the observation results of the image measuring apparatus, it was discovered that the higher the part weight, the better the filling of the microstructures. In conclusion, part weight can be used to evaluate the replication fidelity of micro-feature structured parts primarily; which is an economical and practical method to improve the replication fidelity of microlens arrays based on weight evaluation and optimization.

Micro-CT Sections and Histological Sections of Mouse Skull Defects Implanted with Cartilage Grown in a Rotating Bioreactor

NASA Astrophysics Data System (ADS)

Duke, P. J.; Montufar-Solis, D.; Nguyen, H. C.; Cody, D. D.

2008-06-01

Using cartilage to replace/repair bone is advantageous as no scaffolding is required to form the implant which disappears as bone is formed during the endochondral process. Previously, we demonstrated that cartilage spheroids, grown in a rotating bioreactor, (Synthecon, Inc.) and implanted into a 2 mm skull defect, contributed to healing of the defect. In this report, skulls with or without implants were subjected to microCT scans, and sections from these scans were compared to histological sections of the defect region of demineralized skulls from the same experiment. The area of the defect staining for bone in histological sections of demineralized skulls was the same region shown as mineralized in CT sections. Defects without implants were shown in serial CT sections and histological sections, to be incompletely healed. This study demonstrates that microCT scans are an important corollary to histological studies evaluating the use of implants in healing of bony defects. Supported in part by NIH/NIDCR Training Grant T35 DE07252 and by Cancer Center Support Grant (CA-16672).

Initial steps toward the realization of large area arrays of single photon counting pixels based on polycrystalline silicon TFTs

NASA Astrophysics Data System (ADS)

Liang, Albert K.; Koniczek, Martin; Antonuk, Larry E.; El-Mohri, Youcef; Zhao, Qihua; Jiang, Hao; Street, Robert A.; Lu, Jeng Ping

2014-03-01

The thin-film semiconductor processing methods that enabled creation of inexpensive liquid crystal displays based on amorphous silicon transistors for cell phones and televisions, as well as desktop, laptop and mobile computers, also facilitated the development of devices that have become ubiquitous in medical x-ray imaging environments. These devices, called active matrix flat-panel imagers (AMFPIs), measure the integrated signal generated by incident X rays and offer detection areas as large as ~43×43 cm2. In recent years, there has been growing interest in medical x-ray imagers that record information from X ray photons on an individual basis. However, such photon counting devices have generally been based on crystalline silicon, a material not inherently suited to the cost-effective manufacture of monolithic devices of a size comparable to that of AMFPIs. Motivated by these considerations, we have developed an initial set of small area prototype arrays using thin-film processing methods and polycrystalline silicon transistors. These prototypes were developed in the spirit of exploring the possibility of creating large area arrays offering single photon counting capabilities and, to our knowledge, are the first photon counting arrays fabricated using thin film techniques. In this paper, the architecture of the prototype pixels is presented and considerations that influenced the design of the pixel circuits, including amplifier noise, TFT performance variations, and minimum feature size, are discussed.

Self-aligned top-gate amorphous indium zinc oxide thin-film transistors exceeding low-temperature poly-Si transistor performance.

PubMed

Park, Jae Chul; Lee, Ho-Nyeon; Im, Seongil

2013-08-14

Thin-film transistor (TFT) is a key component of active-matrix flat-panel displays (AMFPDs). These days, the low-temperature poly silicon (LTPS) TFTs are to match with advanced AMFPDs such as the active matrix organic light-emitting diode (AMOLED) display, because of their high mobility for fast pixel switching. However, the manufacturing process of LTPS TFT is quite complicated, costly, and scale-limited. Amorphous oxide semiconductor (AOS) TFT technology is another candidate, which is as simple as that of conventioanl amorphous (a)-Si TFTs in fabrication but provides much superior device performances to those of a-Si TFTs. Hence, various AOSs have been compared with LTPS for active channel layer of the advanced TFTs, but have always been found to be relatively inferior to LTPS. In the present work, we clear the persistent inferiority, innovating the device performaces of a-IZO TFT by adopting a self-aligned coplanar top-gate structure and modifying the surface of a-IZO material. Herein, we demonstrate a high-performance simple-processed a-IZO TFT with mobility of ∼157 cm(2) V(-1) s(-1), SS of ∼190 mV dec(-1), and good bias/photostabilities, which overall surpass the performances of high-cost LTPS TFTs.

Damage localization in aluminum plate with compact rectangular phased piezoelectric transducer array

NASA Astrophysics Data System (ADS)

Liu, Zenghua; Sun, Kunming; Song, Guorong; He, Cunfu; Wu, Bin

2016-03-01

In this work, a detection method for the damage in plate-like structure with a compact rectangular phased piezoelectric transducer array of 16 piezoelectric elements was presented. This compact array can not only detect and locate a single defect (through hole) in plate, but also identify multi-defects (through holes and surface defect simulated by an iron pillar glued to the plate). The experiments proved that the compact rectangular phased transducer array could detect the full range of plate structures and implement multiple-defect detection simultaneously. The processing algorithm proposed in this paper contains two parts: signal filtering and damage imaging. The former part was used to remove noise from signals. Continuous wavelet transform was applicable to signal filtering. Continuous wavelet transform can provide a plot of wavelet coefficients and the signal with narrow frequency band can be easily extracted from the plot. The latter part of processing algorithm was to implement damage detection and localization. In order to accurately locate defects and improve the imaging quality, two images were obtained from amplitude and phase information. One image was obtained with the Total Focusing Method (TFM) and another phase image was obtained with the Sign Coherence Factor (SCF). Furthermore, an image compounding technique for compact rectangular phased piezoelectric transducer array was proposed in this paper. With the proposed technique, the compounded image can be obtained by combining TFM image with SCF image, thus greatly improving the resolution and contrast of image.

Aging characteristics of blue InGaN micro-light emitting diodes at an extremely high current density of 3.5 kA cm-2

NASA Astrophysics Data System (ADS)

Tian, Pengfei; Althumali, Ahmad; Gu, Erdan; Watson, Ian M.; Dawson, Martin D.; Liu, Ran

2016-04-01

The aging characteristics of blue InGaN micro-light emitting diodes (micro-LEDs) with different sizes have been studied at an extremely high current density 3.5 kA cm-2 for emerging micro-LED applications including visible light communication (VLC), micro-LED pumped organic lasers and optogenetics. The light output power of micro-LEDs first increases and then decreases due to the competition of Mg activation in p-GaN layer and defect generation in the active region. The smaller micro-LEDs show less light output power degradation compared with larger micro-LEDs, which is attributed to the lower junction temperature of smaller micro-LEDs. It is found that the high current density without additional junction temperature cannot induce significant micro-LED degradation at room temperature but the combination of the high current density and high junction temperature leads to strong degradation. Furthermore, the cluster LEDs, composed of a micro-LED array, have been developed with both high light output power and less light output degradation for micro-LED applications in solid state lighting and VLC.

Visualization of Subsurface Defects in Composites using a Focal Plane Array Infrared Camera

NASA Technical Reports Server (NTRS)

Plotnikov, Yuri A.; Winfree, William P.

1999-01-01

A technique for enhanced defect visualization in composites via transient thermography is presented in this paper. The effort targets automated defect map construction for multiple defects located in the observed area. Experimental data were collected on composite panels of different thickness with square inclusions and flat bottom holes of different depth and orientation. The time evolution of the thermal response and spatial thermal profiles are analyzed. The pattern generated by carbon fibers and the vignetting effect of the focal plane array camera make defect visualization difficult. An improvement of the defect visibility is made by the pulse phase technique and the spatial background treatment. The relationship between a size of a defect and its reconstructed image is analyzed as well. The image processing technique for noise reduction is discussed.

Presence of the β-triketone herbicide tefuryltrione in drinking water sources and its degradation product in drinking waters.

PubMed

Kamata, Motoyuki; Asami, Mari; Matsui, Yoshihiko

2017-07-01

Triketone herbicides are becoming popular because of their herbicidal activity against sulfonylurea-resistant weeds. Among these herbicides, tefuryltrione (TFT) is the first registered herbicide for rice farming, and recently its distribution has grown dramatically. In this study, we developed analytical methods for TFT and its degradation product 2-chloro-4-methylsulfonyl-3-[(tetrahydrofuran-2-yl-methoxy) methyl] benzoic acid (CMTBA). TFT was found frequently in surface waters in rice production areas at concentrations as high as 1.9 μg/L. The maximum observed concentration was lower than but close to 2 μg/L, which is the Japanese reference concentration of ambient water quality for pesticides. However, TFT was not found in any drinking waters even though the source waters were purified by conventional coagulation and filtration processes; this was due to chlorination, which transforms TFT to CMTBA. The conversion rate of TFT to CMBA on chlorination was almost 100%, and CMTBA was stable in the presence of chlorine. Moreover, CMTBA was found in drinking waters sampled from household water taps at a similar concentration to that of TFT in the source water of the water purification plant. Although the acceptable daily intake and the reference concentration of CMTBA are unknown, the highest concentration in drinking water exceeded 0.1 μg/L, which is the maximum allowable concentration for any individual pesticide and its relevant metabolites in the European Union Drinking Directive. Copyright © 2017 Elsevier Ltd. All rights reserved.

Advanced in-production hotspot prediction and monitoring with micro-topography

NASA Astrophysics Data System (ADS)

Fanton, P.; Hasan, T.; Lakcher, A.; Le-Gratiet, B.; Prentice, C.; Simiz, J.-G.; La Greca, R.; Depre, L.; Hunsche, S.

2017-03-01

At 28nm technology node and below, hot spot prediction and process window control across production wafers have become increasingly critical to prevent hotspots from becoming yield-limiting defects. We previously established proof of concept for a systematic approach to identify the most critical pattern locations, i.e. hotspots, in a reticle layout by computational lithography and combining process window characteristics of these patterns with across-wafer process variation data to predict where hotspots may become yield impacting defects [1,2]. The current paper establishes the impact of micro-topography on a 28nm metal layer, and its correlation with hotspot best focus variations across a production chip layout. Detailed topography measurements are obtained from an offline tool, and pattern-dependent best focus (BF) shifts are determined from litho simulations that include mask-3D effects. We also establish hotspot metrology and defect verification by SEM image contour extraction and contour analysis. This enables detection of catastrophic defects as well as quantitative characterization of pattern variability, i.e. local and global CD uniformity, across a wafer to establish hotspot defect and variability maps. Finally, we combine defect prediction and verification capabilities for process monitoring by on-product, guided hotspot metrology, i.e. with sampling locations being determined from the defect prediction model and achieved prediction accuracy (capture rate) around 75%

Development of Individually Addressable Micro-Mirror-Arrays for Space Applications

NASA Technical Reports Server (NTRS)

Dutta, Sanghamitra B.; Ewin, Audrey J.; Jhabvala, Murzy; Kotecki, Carl A.; Kuhn, Jonathan L.; Mott, D. Brent

2000-01-01

We have been developing a 32 x 32 prototype array of individually addressable Micro-Mirrors capable of operating at cryogenic temperature for Earth and Space Science applications. Micro-Mirror-Array technology has the potential to revolutionize imaging and spectroscopy systems for NASA's missions of the 21st century. They can be used as programmable slits for the Next Generation Space Telescope, as smart sensors for a steerable spectrometer, as neutral density filters for bright scene attenuation etc. The, entire fabrication process is carried out in the Detector Development Laboratory at NASA, GSFC. The fabrication process is low temperature compatible and involves integration of conventional CMOS technology and surface micro-machining used in MEMS. Aluminum is used as the mirror material and is built on a silicon substrate containing the CMOS address circuit. The mirrors are 100 microns x l00 microns in area and deflect by +/- 10 deg induced by electrostatic actuation between two parallel plate capacitors. A pair of thin aluminum torsion straps allow the mirrors to tilt. Finite-element-analysis and closed form solutions using electrostatic and mechanical torque for mirror operation were developed and the results were compared with laboratory performance. The results agree well both at room temperature and at cryogenic temperature. The development demonstrates the first cryogenic operation of two-dimensional Micro-Mirrors with bi-state operation. Larger arrays will be developed meeting requirements for different science applications. Theoretical analysis, fabrication process, laboratory test results and different science applications will be described in detail.

Fatigue testing of low-cost fiberglass composite wind turbine blade materials

NASA Technical Reports Server (NTRS)

Hofer, K. E.; Bennett, L. C.

1981-01-01

The static and fatigue behavior of transverse filament tape (TFT) fiberglass/epoxy and TFT/polyester composites was established by the testing of specimens cut from panels fabricated by a filament winding process used for the construction of large experimental wind turbine blades.

Scaling behavior of fully spin-coated TFT

NASA Astrophysics Data System (ADS)

Mondal, Sandip; Kumar, Arvind; Rao, K. S. R. Koteswara; Venkataraman, V.

2017-05-01

We studied channel scaling behavior of fully spin coated, low temperature solution processed thin film transistor (TFT) fabricated on p++ - Si (˜1021 cm-3) as bottom gate. The solution processed, spin coated 40 nm thick amorphous Indium Gallium Zinc Oxide (a-IGZO) and 50 nm thick amorphous zirconium di-oxide (a-ZrO2) has been used as channel and low leakage dielectric at 350°C respectively. The channel scaling effect of the TFT with different width/length ratio (W/L= 2.5, 5 and 15) for same channel length (L = 10 μm) has been demonstrated. The lowest threshold voltage (Vth) is 6.25 V for the W/L=50/10. The maximum field effect mobility (μFE) has been found to be 0.123 cm2/Vs from W/L of 50/10 with the drain to source voltage (VD) of 10V and 20V gate to source voltage (VG). We also demonstrated that there is no contact resistance effect on the mobility of the fully sol-gel spin coated TFT.

Carbon Nanotube Thin Film Transistors for Flat Panel Display Application.

PubMed

Liang, Xuelei; Xia, Jiye; Dong, Guodong; Tian, Boyuan; Peng, Lianmao

2016-12-01

Carbon nanotubes (CNTs) are promising materials for both high performance transistors for high speed computing and thin film transistors for macroelectronics, which can provide more functions at low cost. Among macroelectronics applications, carbon nanotube thin film transistors (CNT-TFT) are expected to be used soon for backplanes in flat panel displays (FPDs) due to their superior performance. In this paper, we review the challenges of CNT-TFT technology for FPD applications. The device performance of state-of-the-art CNT-TFTs are compared with the requirements of TFTs for FPDs. Compatibility of the fabrication processes of CNT-TFTs and current TFT technologies are critically examined. Though CNT-TFT technology is not yet ready for backplane production line of FPDs, the challenges can be overcome by close collaboration between research institutes and FPD manufacturers in the short term.

Amorphous silicon and organic thin film transistors for electronic applications

NASA Astrophysics Data System (ADS)

Zhou, Lisong

Recently, flexible thin film electronics has attracted huge research interest, and as now, many prototypes are being developed and demonstrated by companies around the world, including displays, logic circuit, and solar cells. Flexible electronics offers many potential advantages: it can not only generate new functions like flexible displays or solar cells, also allow very low cost manufacturing through the use of cheap polymeric substrates and roll-to-roll fabrication. a-Si:H TFT fabrications are compatible with flexible polyimide substrate materials. With the interests in the space environment, for the first time, we tested the performance changes of flexible a-Si:H TFTs, on polyimide substrates, due to irradiation and mechanical stress. Significant changes were found on TFTs after irradiation with fast electrons, which, however, was essentially removed by post-irradiation thermal annealing. On the other hand, few changes were found in TFTs by mechanical stress. These preliminary results indicate that it can be readily engineered for space applications. Furthermore, for the first time, we designed and fabricated ungated n+ muC-Si and gated a-Si:H strain sensors on flexible polyimide substrates. Compared with commercial metallic foil strain sensors, ungated muC-Si sensors and gated a-Si:H sensors are two orders of magnitude smaller in area and consume two orders or magnitude less power. Integration with a-Si:H TFTs can also allow large arrays of strain sensors to be fabricated. To take advantage of lower glass-transition-temperature polymeric substrate materials, reduced processing temperature is desired. The 150°C low-temperature deposition process is achieved by using hydrogen dilution in the PECVD process. The TFT performance and bias stability property are tested similar to that of a 250°C process. These results suggest its viability for practical applications. For even lower process temperature, we have considered organic TFTs. As a practical demonstration, we integrated pentacene TFTs with OLEDs in a simple display. Pentacene TFT passivation techniques were researched, and a PVA and parylene bilayer structure was used. We designed and demonstrated 48 x 48-pixel active matrix OTFTOLED displays, and to our best knowledge, they are the largest on glass substrates and the first on flexible PET substrates. Device performance, uniformity and stability are also compared. These results demonstrate that pentacene TFTs are viable candidates for active-matrix OLED displays and other flexible electronics applications.

Design for low-power and reliable flexible electronics

NASA Astrophysics Data System (ADS)

Huang, Tsung-Ching (Jim)

Flexible electronics are emerging as an alternative to conventional Si electronics for large-area low-cost applications such as e-paper, smart sensors, and disposable RFID tags. By utilizing inexpensive manufacturing methods such as ink-jet printing and roll-to-roll imprinting, flexible electronics can be made on low-cost plastics just like printing a newspaper. However, the key elements of exible electronics, thin-film transistors (TFTs), have slower operating speeds and less reliability than their Si electronics counterparts. Furthermore, depending on the material property, TFTs are usually mono-type -- either p- or n-type -- devices. Making air-stable complementary TFT circuits is very challenging and not applicable to most TFT technologies. Existing design methodologies for Si electronics, therefore, cannot be directly applied to exible electronics. Other inhibiting factors such as high supply voltage, large process variation, and lack of trustworthy device modeling also make designing larger-scale and robust TFT circuits a significant challenge. The major goal of this dissertation is to provide a viable solution for robust circuit design in exible electronics. I will first introduce a reliability simulation framework that can predict the degraded TFT circuits' performance under bias-stress. This framework has been validated using the amorphous-silicon (a-Si) TFT scan driver for TFT-LCD displays. To reuse the existing CMOS design ow for exible electronics, I propose a Pseudo-CMOS cell library that can make TFT circuits operable under low supply voltage and which has post-fabrication tunability for reliability and performance enhancement. This cell library has been validated using 2V self-assembly-monolayer (SAM) organic TFTs with a low-cost shadow-mask deposition process. I will also demonstrate a 3-bit 1.25KS/s Flash ADC in a-Si TFTs, which is based on the proposed Pseudo-CMOS cell library, and explore more possibilities in display, energy, and sensing applications.

Giant Enhancement of Defect-Bound Exciton Luminescence and Suppression of Band-Edge Luminescence in Monolayer WSe2-Ag Plasmonic Hybrid Structures.

PubMed

Johnson, Alex D; Cheng, Fei; Tsai, Yutsung; Shih, Chih-Kang

2017-07-12

We have investigated how the photoluminescence (PL) of WSe 2 is modified when coupled to Ag plasmonic structures at low temperature. Chemical vapor deposition (CVD) grown monolayer WSe 2 flakes were transferred onto a Ag film and a Ag nanotriangle array that had a 1.5 nm Al 2 O 3 capping layer. Using low-temperature (7.5 K) micro-PL mapping, we simultaneously observed enhancement of the defect-bound exciton emission and quenching of the band edge exciton emission when the WSe 2 was on a plasmonic structure. The enhancement of the defect-bound exciton emission was significant with enhancement factors of up to ∼200 for WSe 2 on the nanotriangle array when compared to WSe 2 on a 1.5 nm Al 2 O 3 capped Si substrate with a 300 nm SiO 2 layer. The giant enhancement of the luminescence from the defect-bound excitons is understood in terms of the Purcell effect and increased light absorption. In contrast, the surprising result of luminescence quenching of the bright exciton state on the same plasmonic nanostructure is due to a rather unique electronic structure of WSe 2 : the existence of a dark state below the bright exciton state.

Decreased microRNA levels lead to deleterious increases in neuronal M2 muscarinic receptors in Spinal Muscular Atrophy models

PubMed Central

O'Hern, Patrick J; do Carmo G. Gonçalves, Inês; Brecht, Johanna; López Soto, Eduardo Javier; Simon, Jonah; Chapkis, Natalie; Lipscombe, Diane; Kye, Min Jeong; Hart, Anne C

2017-01-01

Spinal Muscular Atrophy (SMA) is caused by diminished Survival of Motor Neuron (SMN) protein, leading to neuromuscular junction (NMJ) dysfunction and spinal motor neuron (MN) loss. Here, we report that reduced SMN function impacts the action of a pertinent microRNA and its mRNA target in MNs. Loss of the C. elegans SMN ortholog, SMN-1, causes NMJ defects. We found that increased levels of the C. elegans Gemin3 ortholog, MEL-46, ameliorates these defects. Increased MEL-46 levels also restored perturbed microRNA (miR-2) function in smn-1(lf) animals. We determined that miR-2 regulates expression of the C. elegans M2 muscarinic receptor (m2R) ortholog, GAR-2. GAR-2 loss ameliorated smn-1(lf) and mel-46(lf) synaptic defects. In an SMA mouse model, m2R levels were increased and pharmacological inhibition of m2R rescued MN process defects. Collectively, these results suggest decreased SMN leads to defective microRNA function via MEL-46 misregulation, followed by increased m2R expression, and neuronal dysfunction in SMA. DOI: http://dx.doi.org/10.7554/eLife.20752.001 PMID:28463115

Low-temperature sol-gel oxide TFT with a fluoropolymer dielectric to enhance the effective mobility at low operation voltage

NASA Astrophysics Data System (ADS)

Yu, Shang-Yu; Wang, Kuan-Hsun; Zan, Hsiao-Wen; Soppera, Olivier

2017-06-01

In this article, we propose a solution-processed high-performance amorphous indium-zinc oxide (a-IZO) thin-film transistor (TFT) gated with a fluoropolymer dielectric. Compared with a conventional IZO TFT with a silicon nitride dielectric, a fluoropolymer dielectric effectively reduces the operation voltage to less than 3 V and greatly increases the effective mobility 40-fold. We suggest that the dipole layer formed at the dielectric surface facilitates electron accumulation and induces the electric double-layer effect. The dipole-induced hysteresis effect is also investigated.

Retinal instrument

DOEpatents

Britton, Charles L; D& #x27; Urso, Brian R; Chaum, Edward; Simpson, John T; Baba, Justin S; Ericson, M. Nance; Warmack, Robert J

2013-04-23

In one embodiment, the present invention provides a method of removing scar tissue from an eye that includes inserting a device including an array of micro-rods into an eye, wherein at least one glass micro-rod of the array of glass micro-rods includes a sharp feature; contacting a scar tissue with the array of micro-rods; and removing the array of micro-rods and the scar tissue from the eye. In another embodiment, the present invention provides a medical device for engaging a tissue including and an array of glass micro-rods, wherein at least one glass micro-rod of the array of glass micro-rods includes a sharp feature opposite a base of the array of glass micro-rods that is connected to the cannula, wherein the sharp feature of the at least one micro-rod is angled from a plane that is normal to a face of the base of the array of glass micro-rods.

Reduction of solar vector magnetograph data using a microMSP array processor

NASA Technical Reports Server (NTRS)

Kineke, Jack

1990-01-01

The processing of raw data obtained by the solar vector magnetograph at NASA-Marshall requires extensive arithmetic operations on large arrays of real numbers. The objectives of this summer faculty fellowship study are to: (1) learn the programming language of the MicroMSP Array Processor and adapt some existing data reduction routines to exploit its capabilities; and (2) identify other applications and/or existing programs which lend themselves to array processor utilization which can be developed by undergraduate student programmers under the provisions of project JOVE.

Growth and analysis of micro and nano CdTe arrays for solar cell applications

NASA Astrophysics Data System (ADS)

Aguirre, Brandon Adrian

CdTe is an excellent material for infrared detectors and photovoltaic applications. The efficiency of CdTe/CdS solar cells has increased very rapidly in the last 3 years to ˜20% but is still below the maximum theoretical value of 30%. Although the short-circuit current density is close to its maximum of 30 mA/cm2, the open circuit voltage has potential to be increased further to over 1 Volt. The main limitation that prevents further increase in the open-circuit voltage and therefore efficiency is the high defect density in the CdTe absorber layer. Reducing the defect density will increase the open-circuit voltage above 1 V through an increase in the carrier lifetime and concentration to tau >10 ns and p > 10 16 cm-3, respectively. However, the large lattice mismatch (10%) between CdTe and CdS and the polycrystalline nature of the CdTe film are the fundamental reasons for the high defect density and pose a difficult challenge to solve. In this work, a method to physically and electrically isolate the different kinds of defects at the nanoscale and understand their effect on the electrical performance of CdTe is presented. A SiO2 template with arrays of window openings was deposited between the CdTe and CdS to achieve selective-area growth of the CdTe via close-space sublimation. The diameter of the window openings was varied from the micro to the nanoscale to study the effect of size on nucleation, grain growth, and defect density. The resulting structures enabled the possibility to electrically isolate and individually probe micrometer and nanoscale sized CdTe/CdS cells. Electron back-scattered diffraction was used to observe grain orientation and defects in the miniature cells. Scanning and transmission electron microscopy was used to study the morphology, grain boundaries, grain orientation, defect structure, and strain in the layers. Finally, conducting atomic force microscopy was used to study the current-voltage characteristics of the solar cells. An important part of this work was the ability to directly correlate the one-to-one relationship between the electrical performance and defect structure of individual nanoscale cells. This method is general and can be applied to other material systems to study the electrical-microstructure relationship on a one-to-one basis with nanoscale resolution.

Investigation of the evolution of nitrogen defects in flash-lamp-annealed InGaZnO films and their effects on transistor characteristics

NASA Astrophysics Data System (ADS)

Eom, Tae-Yil; Ahn, Chee-Hong; Kang, Jun-Gu; Saad Salman, Muhammad; Lee, Sun-Young; Kim, Yong-Hoon; Lee, Hoo-Jeong; Kang, Chan-Mo; Kang, Chiwon

2018-06-01

In this study, we show the evolution of nitrogen defects during a sol–gel reaction in flash-lamp-annealed InGaZnO (IGZO) films and their effects on the device characteristics of their thin-film transistors (TFTs). The flash lamp annealing (FLA) of the IGZO TFT for 16 s helps achieve a mobility of approximately 7 cm2 V‑1 s‑1. However, further extension of the annealing time results only in drastic increases in carrier concentration and off-current. The X-ray photoelectron spectroscopy (XPS) analysis of the N 1s peak unravels the presence of oxygen-vacancy-associated nitrogen defects and their evolution with annealing time, which is possibly responsible for the increase in carrier concentration.

Genes for 2,4,5-Trichlorophenoxyacetic Acid Metabolism in Burkholderia cepacia AC1100: Characterization of the tftC and tftD Genes and Locations of the tft Operons on Multiple Replicons

PubMed Central

Hübner, Anette; Danganan, Clyde E.; Xun, Luying; Chakrabarty, A. M.; Hendrickson, William

1998-01-01

Burkholderia cepacia AC1100 uses the chlorinated aromatic compound 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) as a sole source of carbon and energy. The enzyme which converts the first intermediate in the pathway, 2,4,5-trichlorophenol, to 5-chlorohydroquinone has been purified and consists of two subunits of 58 and 22 kDa, encoded by the tftC and tftD genes (48). A degenerate primer was designed from the N terminus of the 58-kDa polypeptide and used to isolate a clone containing the tftC and tftD genes from a genomic library of AC1100. The derived amino acid sequences of tftC and tftD show significant homology to the two-component monooxygenases HadA of Burkholderia pickettii, HpaBC of Escherichia coli, and HpaAH of Klebsiella pneumonia. Expression of the tftC and tftD genes appeared to be induced when they were grown in the presence of 2,4,5-T, as shown by RNA slot blot and primer extension analyses. Three sets of cloned tft genes were used as probes to explore the genomic organization of the pathway. Pulsed-field gel electrophoresis analyses of whole chromosomes of B. cepacia AC1100 demonstrated that the genome is comprised of five replicons of 4.0, 2.7, 0.53, 0.34, and 0.15 Mbp, designated I to V, respectively. The tft genes are located on the smaller replicons: the tftAB cluster is on replicon IV, tftEFGH is on replicon III, and copies of the tftC and the tftCD operons are found on both replicons III and IV. When cells were grown in the absence of 2,4,5-T, the genes were lost at high frequency by chromosomal deletions and rearrangements to produce 2,4,5-T-negative mutants. In one mutant, the tftA and tftB genes translocated from one replicon to another, with the concomitant loss of tftEFGH and one copy of tftCD. PMID:9603818

Fabrication of an a-IGZO thin film transistor using selective deposition of cobalt by the self-assembly monolayer (SAM) process.

PubMed

Cho, Young-Je; Kim, HyunHo; Park, Kyoung-Yun; Lee, Jaegab; Bobade, Santosh M; Wu, Fu-Chung; Choi, Duck-Kyun

2011-01-01

Interest in transparent oxide thin film transistors utilizing ZnO material has been on the rise for many years. Recently, however, IGZO has begun to draw more attention due to its higher stability and superior electric field mobility when compared to ZnO. In this work, we address an improved method for patterning an a-IGZO film using the SAM process, which employs a cost-efficient micro-contact printing method instead of the conventional lithography process. After a-IGZO film deposition on the surface of a SiO2-layered Si wafer, the wafer was illuminated with UV light; sources and drains were then patterned using n-octadecyltrichlorosilane (OTS) molecules by a printing method. Due to the low surface energy of OTS, cobalt was selectively deposited on the OTS-free a-IGZO surface. The selective deposition of cobalt electrodes was successful, as confirmed by an optical microscope. The a-IZGO TFT fabricated using the SAM process exhibited good transistor performance: electric field mobility (micro(FE)), threshold voltage (V(th)), subthreshold slope (SS) and on/off ratio were 2.1 cm2/Vs, 2.4 V, 0.35 V/dec and 2.9 x 10(6), respectively.

Low-Temperature, Solution-Processed, Transparent Zinc Oxide-Based Thin-Film Transistors for Sensing Various Solvents.

PubMed

You, Hsin-Chiang; Wang, Cheng-Jyun

2017-02-26

A low temperature solution-processed thin-film transistor (TFT) using zinc oxide (ZnO) film as an exposed sensing semiconductor channel was fabricated to detect and identify various solution solvents. The TFT devices would offer applications for low-cost, rapid and highly compatible water-soluble detection and could replace conventional silicon field effect transistors (FETs) as bio-sensors. In this work, we demonstrate the utility of the TFT ZnO channel to sense various liquids, such as polar solvents (ethanol), non-polar solvents (toluene) and deionized (DI) water, which were dropped and adsorbed onto the channel. It is discussed how different dielectric constants of polar/non-polar solvents and DI water were associated with various charge transport properties, demonstrating the main detection mechanisms of the thin-film transistor.

Effects of structure and oxygen flow rate on the photo-response of amorphous IGZO-based photodetector devices

NASA Astrophysics Data System (ADS)

Jang, Jun Tae; Ko, Daehyun; Choi, Sungju; Kang, Hara; Kim, Jae-Young; Yu, Hye Ri; Ahn, Geumho; Jung, Haesun; Rhee, Jihyun; Lee, Heesung; Choi, Sung-Jin; Kim, Dong Myong; Kim, Dae Hwan

2018-02-01

In this study, we investigated how the structure and oxygen flow rate (OFR) during the sputter-deposition affects the photo-responses of amorphous indium-gallium-zinc-oxide (a-IGZO)-based photodetector devices. As the result of comparing three types of device structures with one another, which are a global Schottky diode, local Schottky diode, and thin-film transistor (TFT), the IGZO TFT with the gate pulse technique suppressing the persistent photoconductivity (PPC) is the most promising photodetector in terms of a high photo-sensitivity and uniform sensing characteristic. In order to analyze the IGZO TFT-based photodetectors more quantitatively, the time-evolution of sub-gap density-of-states (DOS) was directly observed under photo-illumination and consecutively during the PPC-compensating period with applying the gate pulse. It shows that the increased ionized oxygen vacancy (VO2+) defects under photo-illumination was fully recovered by the positive gate pulse and even overcompensated by additional electron trapping. Based on experimentally extracted sub-gap DOS, the origin on PPC was successfully decomposed into the hole trapping and the VO ionization. Although the VO ionization is enhanced in lower OFR (O-poor) device, the PPC becomes more severe in high OFR (O-rich) device because the hole trapping dominates the PPC in IGZO TFT under photo-illumination rather than the VO ionization and more abundant holes are trapped into gate insulator and/or interface in O-rich TFTs. Similarly, the electron trapping during the PPC-compensating period with applying the positive gate pulse becomes more prominent in O-rich TFTs. It is attributed to more hole/electron traps in the gate insulator and/or interface, which is associated with oxygen interstitials, or originates from the ion bombardment-related lower quality gate oxide in O-rich devices.

X-ray tomography of powder injection moulded micro parts using synchrotron radiation

NASA Astrophysics Data System (ADS)

Heldele, R.; Rath, S.; Merz, L.; Butzbach, R.; Hagelstein, M.; Haußelt, J.

2006-05-01

Powder injection moulding is one of the most promising replication methods for the mass production of metal and ceramic micro parts. The material for injection moulding, a so-called feedstock, consists of thermoplastic binder components and inorganic filler with approximately equal volume fractions. Injection moulding of the feedstock leads to a green part that can be processed to a dense metal or ceramic micro part by debinding and sintering. During the injection moulding process extremely high shear rates are applied. This promotes the separation of powder and binder leading to a particle density variation in the green part causing anisotropic shrinkage during post-processing. The knowledge of introducing density gradients and defects would consequently allow the optimization of the feedstock, the moulding parameters and the validation of a simulation tool based on the Dissipative Particle Dynamics which is currently under development, as well. To determine the particle density and defect distribution in micro parts synchrotron radiation tomography in absorption mode was used. Due to its parallel and monochromatic character a quantitative reconstruction, free of beam hardening artifacts, is possible. For the measurement, bending bars consisting of dispersed fused silica particles in a polymeric matrix were used. The presented results using this set-up show that crucial defects and density variations can be detected.

Conducting glasses recovered from thin film transistor liquid crystal display wastes for dye-sensitized solar cell cathodes.

PubMed

Chen, C-C; Chang, F-C; Peng, C Y; Wang, H Paul

2015-01-01

Transparent conductive glasses such as thin film transistor (TFT) array and colour filter glasses were recovered from the TFT-liquid crystal display panel wastes by dismantling and sonic cleaning. Noble metals (i.e. platinum (Pt)) and indium tin oxide (ITO) are generally used in the cathode of a dye-sensitized solar cell (DSSC). To reduce the DSSC cost, Pt was replaced with nano nickel-encapsulated carbon-shell (Ni@C) nanoparticles, which were prepared by carbonization of Ni²⁺-β-cyclodextrin at 673 K for 2 h. The recovered conductive glasses were used in the DSSC electrodes in the substitution of relatively expensive ITO. Interestingly, the efficiency of the DSSC having the Ni@C-coated cathode is as high as 2.54%. Moreover, the cost of the DSSC using the recovered materials can be reduced by at least 24%.

A Flexible Annular-Array Imaging Platform for Micro-Ultrasound

PubMed Central

Qiu, Weibao; Yu, Yanyan; Chabok, Hamid Reza; Liu, Cheng; Tsang, Fu Keung; Zhou, Qifa; Shung, K. Kirk; Zheng, Hairong; Sun, Lei

2013-01-01

Micro-ultrasound is an invaluable imaging tool for many clinical and preclinical applications requiring high resolution (approximately several tens of micrometers). Imaging systems for micro-ultrasound, including single-element imaging systems and linear-array imaging systems, have been developed extensively in recent years. Single-element systems are cheaper, but linear-array systems give much better image quality at a higher expense. Annular-array-based systems provide a third alternative, striking a balance between image quality and expense. This paper presents the development of a novel programmable and real-time annular-array imaging platform for micro-ultrasound. It supports multi-channel dynamic beamforming techniques for large-depth-of-field imaging. The major image processing algorithms were achieved by a novel field-programmable gate array technology for high speed and flexibility. Real-time imaging was achieved by fast processing algorithms and high-speed data transfer interface. The platform utilizes a printed circuit board scheme incorporating state-of-the-art electronics for compactness and cost effectiveness. Extensive tests including hardware, algorithms, wire phantom, and tissue mimicking phantom measurements were conducted to demonstrate good performance of the platform. The calculated contrast-to-noise ratio (CNR) of the tissue phantom measurements were higher than 1.2 in the range of 3.8 to 8.7 mm imaging depth. The platform supported more than 25 images per second for real-time image acquisition. The depth-of-field had about 2.5-fold improvement compared to single-element transducer imaging. PMID:23287923

Interpretation and Regulation of Electronic Defects in IGZO TFTs Through Materials & Processes

NASA Astrophysics Data System (ADS)

Mudgal, Tarun

The recent rise in the market for consumer electronics has fueled extensive research in the field of display. Thin-Film Transistors (TFTs) are used as active matrix switching devices for flat panel displays such as LCD and OLED. The following investigation involves an amorphous metal-oxide semiconductor that has the potential for improved performance over current technology, while maintaining high manufacturability. Indium-Gallium-Zinc-Oxide (IGZO) is a semiconductor material which is at the onset of commercialization. The low-temperature large-area deposition compatibility of IGZO makes it an attractive technology from a manufacturing standpoint, with an electron mobility that is 10 times higher than current amorphous silicon technology. The stability of IGZO TFTs continues to be a challenge due to the presence of defect states and problems associated with interface passivation. The goal of this dissertation is to further the understanding of the role of defect states in IGZO, and investigate materials and processes needed to regulate defects to the level at which the associated influence on device operation is controlled. The relationships between processes associated with IGZO TFT operation including IGZO sputter deposition, annealing conditions and back-channel passivation are established through process experimentation, materials analysis, electrical characterization, and modeling of electronic properties and transistor behavior. Each of these components has been essential in formulating and testing several hypotheses on the mechanisms involved, and directing efforts towards achieving the goal. Key accomplishments and quantified results are summarized as follows: • XPS analysis identified differences in oxygen vacancies in samples before and after oxidizing ambient annealing at 400 °C, showing a drop in relative integrated area of the O-1s peak from 32% to 19%, which experimentally translates to over a thousand fold decrease in the channel free electron concentration. • Transport behavior at cryogenic temperatures identified variable range hopping as the electron transport mechanism at temperature below 130 K, whereas at temperature greater than 130 K, the current vs temperature response followed an Arrhenius relationship consistent with extended state transport. • Refinement of an IGZO material model for TCAD simulation, which consists of oxygen vacancy donors providing an integrated space charge concentration NVO = +5e15 cm-3, and acceptor-like band-tail states with a total integrated ionized concentration of NTA = -2e18 cm-3. An intrinsic electron mobility was established to be micron = 12.7 cm2/V·s. • A SPICE-compatible 2D on-state operation model for IGZO TFTs has been developed which includes the integration of drain-impressed deionization of band-tail states and results in a 2D modification of free channel charge. The model provides an exceptional match to measured data and TCAD simulation, with model parameters for channel mobility (microch = 12 cm2/V·s) and threshold voltage (V T = 0.14 V) having a close match to TCAD analogs. • TCAD material and device models for bottom-gate and double-gate TFT configurations have been developed which depict the role of defect states on device operation, as well as provide insight and support of a presented hypothesis on DIBL like device behavior associated with back-channel interface trap inhomogeneity. This phenomenon has been named Trap Associated Barrier Lowering (TABL). • A process integration scheme has been developed that includes IGZO back-channel passivation with PECVD SiO2, furnace annealing in O2 at 400 °C, and a thin capping layer of alumina deposited via atomic layer deposition. This process supports device stability when subjected to negative and positive bias stress conditions, and thermal stability up to 140 °C. It also enables TFT operation at short channel lengths (Leff 3 microm) with steep subthreshold characteristics (SS 120 mV/dec). The details of these contributions in the interpretation and regulation of electronic defect states in IGZO TFTs is presented, along with the support of device characteristics that are among the best reported in the literature. Additional material on a complementary technology which utilizes flash-lamp annealing of amorphous silicon will also be described. Flash-Lamp Annealed Polycrystalline Silicon (FLAPS) has realized n-channel and p-channel TFTs with promising results, and may provide an option for future applications with the highest performance demands. IGZO is rapidly emerging as the candidate to replace a-Si:H and address the performance needs of display products produced by large panel manufacturing.

Combustion synthesized indium-tin-oxide (ITO) thin film for source/drain electrodes in all solution-processed oxide thin-film transistors

NASA Astrophysics Data System (ADS)

Tue, Phan Trong; Inoue, Satoshi; Takamura, Yuzuru; Shimoda, Tatsuya

2016-06-01

We report combustion solution synthesized (SCS) indium-tin-oxide (ITO) thin film, which is a well-known transparent conductive oxide, for source/drain (S/D) electrodes in solution-processed amorphous zirconium-indium-zinc-oxide TFT. A redox-based combustion synthetic approach is applied to ITO thin film using acetylacetone as a fuel and metal nitrate as oxidizer. The structural and electrical properties of SCS-ITO precursor solution and thin films were systematically investigated with changes in tin concentration, indium metal precursors, and annealing conditions such as temperature, time, and ambient. It was found that at optimal conditions the SCS-ITO thin film exhibited high crystalline quality, atomically smooth surface (RMS ~ 4.1 Å), and low electrical resistivity (4.2 × 10-4 Ω cm). The TFT using SCS-ITO film as the S/D electrodes showed excellent electrical properties with negligible hysteresis. The obtained "on/off" current ratio, subthreshold swing factor, subthreshold voltage, and field-effect mobility were 5 × 107, 0.43 V/decade, 0.7 V, and 2.1 cm2/V s, respectively. The performance and stability of the SCS-ITO TFT are comparable to those of the sputtered-ITO TFT, emphasizing that the SCS-ITO film is a promising candidate for totally solution-processed oxide TFTs.

a-Si:H TFT-silicon hybrid low-energy x-ray detector

DOE PAGES

Shin, Kyung -Wook; Karim, Karim S.

2017-03-15

Direct conversion crystalline silicon X-ray imagers are used for low-energy X-ray photon (4-20 keV) detection in scientific research applications such as protein crystallography. In this paper, we demonstrate a novel pixel architecture that integrates a crystalline silicon X-ray detector with a thin-film transistor amorphous silicon pixel readout circuit. We describe a simplified two-mask process to fabricate a complete imaging array and present preliminary results that show the fabricated pixel to be sensitive to 5.89-keV photons from a low activity Fe-55 gamma source. Furthermore, this paper presented can expedite the development of high spatial resolution, low cost, direct conversion imagers formore » X-ray diffraction and crystallography applications.« less

Full-frame, programmable hyperspectral imager

DOE Office of Scientific and Technical Information (OSTI.GOV)

Love, Steven P.; Graff, David L.

A programmable, many-band spectral imager based on addressable spatial light modulators (ASLMs), such as micro-mirror-, micro-shutter- or liquid-crystal arrays, is described. Capable of collecting at once, without scanning, a complete two-dimensional spatial image with ASLM spectral processing applied simultaneously to the entire image, the invention employs optical assemblies wherein light from all image points is forced to impinge at the same angle onto the dispersing element, eliminating interplay between spatial position and wavelength. This is achieved, as examples, using telecentric optics to image light at the required constant angle, or with micro-optical array structures, such as micro-lens- or capillary arrays,more » that aim the light on a pixel-by-pixel basis. Light of a given wavelength then emerges from the disperser at the same angle for all image points, is collected at a unique location for simultaneous manipulation by the ASLM, then recombined with other wavelengths to form a final spectrally-processed image.« less

Restoring speech perception with cochlear implants by spanning defective electrode contacts.

PubMed

Frijns, Johan H M; Snel-Bongers, Jorien; Vellinga, Dirk; Schrage, Erik; Vanpoucke, Filiep J; Briaire, Jeroen J

2013-04-01

Even with six defective contacts, spanning can largely restore speech perception with the HiRes 120 speech processing strategy to the level supported by an intact electrode array. Moreover, the sound quality is not degraded. Previous studies have demonstrated reduced speech perception scores (SPS) with defective contacts in HiRes 120. This study investigated whether replacing defective contacts by spanning, i.e. current steering on non-adjacent contacts, is able to restore speech recognition to the level supported by an intact electrode array. Ten adult cochlear implant recipients (HiRes90K, HiFocus1J) with experience with HiRes 120 participated in this study. Three different defective electrode arrays were simulated (six separate defective contacts, three pairs or two triplets). The participants received three take-home strategies and were asked to evaluate the sound quality in five predefined listening conditions. After 3 weeks, SPS were evaluated with monosyllabic words in quiet and in speech-shaped background noise. The participants rated the sound quality equal for all take-home strategies. SPS with background noise were equal for all conditions tested. However, SPS in quiet (85% phonemes correct on average with the full array) decreased significantly with increasing spanning distance, with a 3% decrease for each spanned contact.

MEMS floating element sensor array for wall shear stress measurement under a turbulent boundary layer

NASA Astrophysics Data System (ADS)

Zong, Zhaowang

A novel electrochromic thin film transistor (EC-TFT) was fabricated and characterized in this work. This concept relies on ion transport to control gating. The channel material is tungsten oxide (WOx), produced by reactive magnetron sputtering. In its oxidized state WO3 is a transparent, wide band gap insulator (> 3 eV). However upon intercalation of light ions (H+, Li+) the material becomes both electrically conducting and opaque to visible light. This allows the EC-TFT to generate a complementary optical response. We optimized the fabrication of individual layers of the EC-TFT, and found that controlling the stoichiometry of WOx is a key step. Using RF magnetron sputtering, it was found that there is a narrow window to obtain material capable of reversible switching. Fully oxidized films proved it is difficult to intercalate ions efficiently. In contrast, insufficient oxygen produced films that were always in a metallic like state. Best results were obtained with the sputter power set at 200 W using O2 fractions of 42%-46% in argon. In the preliminary studies, the device was tested in a two-step fashion. First, devices were placed in solution and cyclic voltammetry was used to set the level of ion intercalation. Samples were then removed from the electrolyte, dried, and the source/drain current was measured on a probe station. This demonstrated the concept of the EC-TFT, showing that the transistor could be turned on and off reversely with a current ratio of Ion/Ioff ~ 1000, and showed significant color change during the intercalation. However, the conductivity in off state was too high to be a promising transistor, the two step approach made the data rather noisy, it was difficult to make good contacts and this was not an in situ measurement. In order to get the in situ measurement, macrodevices with large electrodes were fabricated and characterized, which made it easier to make electrical contacts. However, after the initial cycle the macrodevices were always in on state and could not be turned off because of the dielectric. In addition, it showed no significant color change. The top source/drain structure showed similar behavior as the bottom configuration. It was found that in these configurations the supply of electrons was insufficient to allow intercalation, and permanent defects in the Al2O3 dielectric developed to compensate. To address these issues, 3-terminal devices were fabricated and characterized simultaneously. These devices showed similar behaviors with the preliminary 2-step device. The IDS increased with decreasing gate biasing with a low threshold voltage -0.8 V. In addition, we observed the color changing. However, the conduction through the electrolyte resulted very low on/off ratio (<5). In conclusion, it is the conduction through the electrolyte contributes to the low on/off ratio.

Prototype of IGZO-TFT preamplifier and analog counter for pixel detector

NASA Astrophysics Data System (ADS)

Shimazoe, K.; Koyama, A.; Takahashi, H.; Shindoh, T.; Miyoshi, H.

2017-02-01

IGZO-TFT (Indium Galium Zinc Oxide-Thin Film Transistor) is a promising technology for controlling large display areas and large area sensors because of its very low leakage current in the off state and relatively low cost. IGZO has been used as a switching gate for a large area flat-panel detector. The photon counting capability for X-ray medical imaging has been investigated and expected for low-dose exposure and material determination. Here the design and fabrication of a charge sensitive preamplifier and analog counter using IGZO-TFT processes and its performance are reported for the first time to be used for radiation photon counting applications.

A novel method for fabrication of continuous-relief optical elements

NASA Astrophysics Data System (ADS)

Guo, Xiaowei; Du, Jinglei; Chen, Mingyong; Ma, Yanqin; Zhu, Jianhua; Peng, Qinjun; Guo, Yongkang; Du, Chunlei

2005-08-01

A novel method for the fabrication of continuous micro-optical components is presented in this paper. It employs a computer controlled spatial-light-modulator (SLM) as a switchable projection mask and silver-halide sensitized gelatin (SHSG) as recording material. By etching SHSG with enzyme solution, the micro-optical components with relief modulation can be generated through special processing procedures. The principles of digital SLM-based lithography and enzyme etching SHSG are discussed in detail, and microlens arrays, micro axicon-lens arrays and gratings with good profile were achieved. This method is simple, cheap and the aberration in processing procedures can be in-situ corrected in the step of designing mask, so it is a practical method to fabricate continuous profile for low-volume production.

Low-Temperature, Solution-Processed, Transparent Zinc Oxide-Based Thin-Film Transistors for Sensing Various Solvents

PubMed Central

You, Hsin-Chiang; Wang, Cheng-Jyun

2017-01-01

A low temperature solution-processed thin-film transistor (TFT) using zinc oxide (ZnO) film as an exposed sensing semiconductor channel was fabricated to detect and identify various solution solvents. The TFT devices would offer applications for low-cost, rapid and highly compatible water-soluble detection and could replace conventional silicon field effect transistors (FETs) as bio-sensors. In this work, we demonstrate the utility of the TFT ZnO channel to sense various liquids, such as polar solvents (ethanol), non-polar solvents (toluene) and deionized (DI) water, which were dropped and adsorbed onto the channel. It is discussed how different dielectric constants of polar/non-polar solvents and DI water were associated with various charge transport properties, demonstrating the main detection mechanisms of the thin-film transistor. PMID:28772592

Electroless-plated Ni pattern with catalyst printing on indium-gallium-zinc oxide surface

NASA Astrophysics Data System (ADS)

Onoue, Miki; Ogura, Shintaro; Kusaka, Yasuyuki; Fukuda, Nobuko; Yamamoto, Noritaka; Kojima, Keisuke; Chikama, Katsumi; Ushijima, Hirobumi

2017-05-01

Electroless plated metals have been used for wiring and electrodes in the manufacture of electronic devices. To obtain plated patterns, etching and photoresist are generally used. However, through catalyst patterning by printing, we can obtain metal patterns without etching and photoresists by electroless plating. Solution-processed indium-gallium-zinc oxide (IGZO) has received significant attention for showing high performance and ease of preparation in air atmosphere. In this study, we prepared an electroless plated pattern by catalyst printing as electrodes of IGZO TFT. There are few reports on the application of plated metal electrodes prepared by catalyst printing to the source and drain electrodes of IGZO TFT. The prepared IGZO TFT exhibits a typical current-voltage (I-V) curve. The plated electrodes caused many problems such as performance degradation. However, our result showed that the plated metal electrodes can drive IGZO TFT. In addition, we confirm plated metal growth into the catalyst layer by cross sectional scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM/EDS) of the plated Ni. We discuss the relevance of the measured work function (WF) of the electrode materials and the performance of IGZO TFT.

Friction Stir Weld Inspection Through Conductivity Imaging Using Shaped Field MWM(Registered Trademark) - Arrays

NASA Technical Reports Server (NTRS)

Goldfine, Neil; Grundy, David; Zilberstein, Vladimir; Kinchen, David G.; McCool, Alex (Technical Monitor)

2002-01-01

Friction Stir Welds (FSW) of Al 2195-T8 and Al 2219-T8, provided by Lockheed Martin Michoud Operations, were inspected for lack-of-penetration (LOP) defects using a custom designed MWM-Array, a multi-element eddy-current sensor. MWM (registered trademark) electrical conductivity mapping demonstrated high sensitivity to LOP as small as 0.75 mm (0.03 in.), as confirmed by metallographic data that characterized the extent of LOP defects. High sensitivity and high spatial resolution was achieved via a 37-element custom designed MWM-Array allowing LOP detection using the normalized longitudinal component of the MWM measured conductivity. This permitted both LOP detection and correlation of MWM conductivity features with the LOP defect size, as changes in conductivity were apparently associated with metallurgical features within the near-surface layer of the LOP defect zone. MWM conductivity mapping reveals information similar to macro-etching as the MWM-Array is sensitive to small changes in conductivity due to changes in microstructure associated with material thermal processing, in this case welding. The electrical conductivity measured on the root side of FSWs varies across the weld due to microstructural differences introduced by the FSW process, as well as those caused by planar flaws. Weld metal, i.e., dynamically recrystallized zone (DXZ), thermomechanically affected zone (TMZ), heat-affected zone (HAZ), and parent metal (PM) are all evident in the conductivity maps. While prior efforts had met with limited success for NDE (Nondestructive Evaluation) of dissimilar alloy, Al2219 to Al2195 FSW, the new custom designed multi-element MWM-Array achieved detection of all LOP defects even in dissimilar metal welds.

High Stability Induced by the TiN/Ti Interlayer in Three-Dimensional Si/Ge Nanorod Arrays as Anode in Micro Lithium Ion Battery.

PubMed

Yue, Chuang; Yu, Yingjian; Wu, Zhenguo; Sun, Shibo; He, Xu; Li, Juntao; Zhao, Libo; Wu, Suntao; Li, Jing; Kang, Junyong; Lin, Liwei

2016-03-01

Three-dimensional (3D) Si/Ge-based micro/nano batteries are promising lab-on-chip power supply sources because of the good process compatibility with integrated circuits and Micro/Nano-Electro-Mechanical System technologies. In this work, the effective interlayer of TiN/Ti thin films were introduced to coat around the 3D Si nanorod (NR) arrays before the amorphous Ge layer deposition as anode in micro/nano lithium ion batteries, thus the superior cycling stability was realized by reason for the restriction of Si activation in this unique 3D matchlike Si/TiN/Ti/Ge NR array electrode. Moreover, the volume expansion properties after the repeated lithium-ion insertion/extraction were experimentally investigated to evidence the superior stability of this unique multilayered Si composite electrode. The demonstration of this wafer-scale, cost-effective, and Si-compatible fabrication for anodes in Li-ion micro/nano batteries provides new routes to configurate more efficient 3D energy storage systems for micro/nano smart semiconductor devices.

Exposure-dependent incorporation of trifluridine into DNA of tumors and white blood cells in tumor-bearing mouse.

PubMed

Yamashita, Fumiaki; Komoto, Ikumi; Oka, Hiroaki; Kuwata, Keizo; Takeuchi, Mayuko; Nakagawa, Fumio; Yoshisue, Kunihiro; Chiba, Masato

2015-08-01

Trifluridine (TFT) is an antitumor component of a novel nucleoside antitumor agent, TAS-102, which consists of TFT and tipiracil hydrochloride (thymidine phosphorylase inhibitor). Incorporation of TFT into DNA is a probable mechanism of antitumor activity and hematological toxicity. The objective of this study was to examine the TFT incorporation into tumor- and white blood cell-DNA, and to elucidate the mechanism of TFT-related effect and toxicity. TFT effect on the colony formation of mouse bone marrow cells was also investigated. Pharmacokinetics of TFT was determined in nude mice after single oral administration of TAS-102, while the antitumor activity and body weight change were evaluated in the tumor-bearing nude mice after multiple oral administrations for 2 weeks. TFT concentrations in the blood- and tumor-DNA were determined by LC/MS/MS. The colony formation was evaluated by CFU-GM assay. TFT systemic exposure in plasma increased dose-dependently. The tumor growth rate and body weight gain decreased dose-dependently, but TFT concentrations in the DNA of tumor tissues and white blood cells increased dose-dependently. TFT inhibited colony formation of bone marrow cells in a concentration-dependent manner. A significant relationship between systemic exposure of TFT and pharmacological effects including the antitumor activity and body weight change was well explained by the TFT incorporation into DNA. TFT inhibited proliferations of mouse bone marrow cells and human colorectal carcinoma cells implanted to nude mice dose-dependently. The highest tolerable TFT exposure provides the highest antitumor activity, and the hematological toxicity may serve as a potential surrogate indicator of TAS-102 efficacy.

The novel thymidylate synthase inhibitor trifluorothymidine (TFT) and TRAIL synergistically eradicate non-small cell lung cancer cells.

PubMed

Azijli, Kaamar; van Roosmalen, Ingrid A M; Smit, Jorn; Pillai, Saravanan; Fukushima, Masakazu; de Jong, Steven; Peters, Godefridus J; Bijnsdorp, Irene V; Kruyt, Frank A E

2014-06-01

TRAIL, a tumor selective anticancer agent, may be used for the treatment of non-small cell lung cancer (NSCLC). However, TRAIL resistance is frequently encountered. Here, the combined use of TRAIL with trifluorothymidine (TFT), a thymidylate synthase inhibitor, was examined for sensitizing NSCLC cells to TRAIL. Interactions between TRAIL and TFT were studied in NSCLC cells using growth inhibition and apoptosis assays. Western blotting and flow cytometry were used to investigate underlying mechanisms. The combined treatment of TFT and TRAIL showed synergistic cytotoxicity in A549, H292, H322 and H460 cells. For synergistic activity, the sequence of administration was important; TFT treatment followed by TRAIL exposure did not show sensitization. Combined TFT and TRAIL treatment for 24 h followed by 48 h of TFT alone was synergistic in all cell lines, with combination index values below 0.9. The treatments affected cell cycle progression, with TRAIL inducing a G1 arrest and TFT, a G2/M arrest. TFT activated Chk2 and reduced Cdc25c levels known to cause G2/M arrest. TRAIL-induced caspase-dependent apoptosis was enhanced by TFT, whereas TFT alone mainly induced caspase-independent death. TFT increased the expression of p53 and p21/WAF1, and p53 was involved in the increase of TRAIL-R2 surface expression. TFT also caused downregulation of cFLIP and XIAP and increased Bax expression. TFT enhances TRAIL-induced apoptosis in NSCLC cells by sensitizing the apoptotic machinery at different levels in the TRAIL pathway. Our findings suggest a possible therapeutic benefit of the combined use of TFT and TRAIL in NSCLC.

Simulation Study of the Localization of a Near-Surface Crack Using an Air-Coupled Ultrasonic Sensor Array

PubMed Central

Delrue, Steven; Aleshin, Vladislav; Sørensen, Mikael; De Lathauwer, Lieven

2017-01-01

The importance of Non-Destructive Testing (NDT) to check the integrity of materials in different fields of industry has increased significantly in recent years. Actually, industry demands NDT methods that allow fast (preferably non-contact) detection and localization of early-stage defects with easy-to-interpret results, so that even a non-expert field worker can carry out the testing. The main challenge is to combine as many of these requirements into one single technique. The concept of acoustic cameras, developed for low frequency NDT, meets most of the above-mentioned requirements. These cameras make use of an array of microphones to visualize noise sources by estimating the Direction Of Arrival (DOA) of the impinging sound waves. Until now, however, because of limitations in the frequency range and the lack of integrated nonlinear post-processing, acoustic camera systems have never been used for the localization of incipient damage. The goal of the current paper is to numerically investigate the capabilities of locating incipient damage by measuring the nonlinear airborne emission of the defect using a non-contact ultrasonic sensor array. We will consider a simple case of a sample with a single near-surface crack and prove that after efficient excitation of the defect sample, the nonlinear defect responses can be detected by a uniform linear sensor array. These responses are then used to determine the location of the defect by means of three different DOA algorithms. The results obtained in this study can be considered as a first step towards the development of a nonlinear ultrasonic camera system, comprising the ultrasonic sensor array as the hardware and nonlinear post-processing and source localization software. PMID:28441738

Trifluorothymidine resistance is associated with decreased thymidine kinase and equilibrative nucleoside transporter expression or increased secretory phospholipase A2.

PubMed

Temmink, Olaf H; Bijnsdorp, Irene V; Prins, Henk-Jan; Losekoot, Nienke; Adema, Auke D; Smid, Kees; Honeywell, Richard J; Ylstra, Bauke; Eijk, Paul P; Fukushima, Masakazu; Peters, Godefridus J

2010-04-01

Trifluorothymidine (TFT) is part of the novel oral formulation TAS-102, which is currently evaluated in phase II studies. Drug resistance is an important limitation of cancer therapy. The aim of the present study was to induce resistance to TFT in H630 colon cancer cells using two different schedules and to analyze the resistance mechanism. Cells were exposed either continuously or intermittently to TFT, resulting in H630-cTFT and H630-4TFT, respectively. Cells were analyzed for cross-resistance, cell cycle, protein expression, and activity of thymidine phosphorylase (TP), thymidine kinase (TK), thymidylate synthase (TS), equilibrative nucleoside transporter (hENT), gene expression (microarray), and genomic alterations. Both cell lines were cross-resistant to 2'-deoxy-5-fluorouridine (>170-fold). Exposure to IC(75)-TFT increased the S/G(2)-M phase of H630 cells, whereas in the resistant variants, no change was observed. The two main target enzymes TS and TP remained unchanged in both TFT-resistant variants. In H630-4TFT cells, TK protein expression and activity were decreased, resulting in less activated TFT and was most likely the mechanism of TFT resistance. In H630-cTFT cells, hENT mRNA expression was decreased 2- to 3-fold, resulting in a 5- to 10-fold decreased TFT-nucleotide accumulation. Surprisingly, microarray-mRNA analysis revealed a strong increase of secretory phospholipase-A2 (sPLA2; 47-fold), which was also found by reverse transcription-PCR (RT-PCR; 211-fold). sPLA2 inhibition reversed TFT resistance partially. H630-cTFT had many chromosomal aberrations, but the exact role of sPLA2 in TFT resistance remains unclear. Altogether, resistance induction to TFT can lead to different mechanisms of resistance, including decreased TK protein expression and enzyme activity, decreased hENT expression, as well as (phospho)lipid metabolism. Mol Cancer Ther; 9(4); 1047-57. (c)2010 AACR.

Alumina nanoparticle/polymer nanocomposite dielectric for flexible amorphous indium-gallium-zinc oxide thin film transistors on plastic substrate with superior stability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lai, Hsin-Cheng; Pei, Zingway, E-mail: zingway@dragon.nchu.edu.tw; Graduate Institute of Optoelectronic Engineering, National Chung Hsing University, Taichung 40227, Taiwan

In this study, the Al{sub 2}O{sub 3} nanoparticles were incorporated into polymer as a nono-composite dielectric for used in a flexible amorphous Indium-Gallium-Zinc Oxide (a-IGZO) thin-film transistor (TFT) on a polyethylene naphthalate substrate by solution process. The process temperature was well below 100 °C. The a-IGZO TFT exhibit a mobility of 5.13 cm{sup 2}/V s on the flexible substrate. After bending at a radius of 4 mm (strain = 1.56%) for more than 100 times, the performance of this a-IGZO TFT was nearly unchanged. In addition, the electrical characteristics are less altered after positive gate bias stress at 10 V for 1500 s. Thus, this technology ismore » suitable for use in flexible displays.« less

Phased Array Probe Optimization for the Inspection of Titanium Billets

NASA Astrophysics Data System (ADS)

Rasselkorde, E.; Cooper, I.; Wallace, P.; Lupien, V.

2010-02-01

The manufacturing process of titanium billets can produce multiple sub-surface defects that are particularly difficult to detect during the early stages of production. Failure to detect these defects can lead to subsequent in-service failure. A new and novel automated quality control system is being developed for the inspection of titanium billets destined for use in aerospace applications. The sensors will be deployed by an automated system to minimise the use of manual inspections, which should improve the quality and reliability of these critical inspections early on in the manufacturing process. This paper presents the first part of the work, which is the design and the simulation of the phased array ultrasonic inspection of the billets. A series of phased array transducers were designed to optimise the ultrasonic inspection of a ten inch diameter billet made from Titanium 6Al-4V. A comparison was performed between different probes including a 2D annular sectorial array.

Amorphous silicon thin-film transistor active-matrix for reflective cholesteric liquid crystal displays

NASA Astrophysics Data System (ADS)

Nahm, Jeong-Yeop

Reflective cholesteric liquid crystal displays (Ch-LCDs) have advantages, such as, high brightness, low power consumption, and wide viewing angle, since they do not need any polarizer, color filter, and backlight. Furthermore, due to their bistability Ch-LCDs can retain their images virtually forever without additional power consumption. But conventional passive-matrix addressing of Ch-LCDs allows only a slow image updating speed. Active-matrix addressing should allow fast image updating or video-rate operation. However, because the threshold voltage of cholesteric, liquid crystal is high (>20V), the switching devices for active-matrix addressing should satisfy required characteristics even under high bias conditions. In order to investigate the applicability of hydrogenated amorphous silicon thin film transistors (a-Si:H TFTs) for the switching devices of active-matrix (AM) Ch-LCDs, the characteristics of conventional and gate offset high voltage a-Si:H TTFs were examined under high bias conditions. And it was concluded that high OFF-current of conventional a-Si:H TFTs and low ON-current of gate offset high voltage a-Si:H TFTs were main problems for reflective AM Ch-LCD applications. In order to improve the TFT characteristics under high bias conditions, we propose two new a-Si:H TFT structures called gate planarized (GP) and buried field plate (BFP) high voltage a-Si:H TFTs. Firstly, in the GP a-Si:H TFTs, we used a thick spin-coated benzocyclobutene (BCB) layer beneath a thin hydrogenated amorphous silicon nitride (a-SiNx:H) layer for gate insulator. The GP a-Si:H TFT showed normal TFT characteristic up to VGS = VDS = ˜100 V without any device failure. But TFT ON-current of GP a-Si:H TFT was reduced due to the introduction of the thick low dielectric BCB layer. Secondly, in the BFP a-Si:H TFT, an offset region and a buried field plate were introduced between the drain/source and gate electrodes to reduce the electric field in the pinch-off region. For this BFP a-Si:H TFT, a low OFF-current (1.04 pA) and a high ON/OFF-current ratio (5.68 x 106) up to VGS = VDS = ˜30 V were obtained. Based on our a-Si:H TFTs studies, we designed an a-Si:H TFT active-matrix panel and fabricated the AM Ch-LCDs either by optimizing a-Si:H TFT processing or adopting the GP a-Si:H TFT technology. The fabricated a-Si:H TFT active-matrix panels can be operated at the voltage of 50 and 60V, applied to the data and gate lines, respectively. With the a-Si:H TFT active-matrix panels, the AM Ch-LCDs were fabricated and operated with the frame rate of 60 Hz and the maximum contrast ratio of ˜30.

Thin-Film Transistors Fabricated Using Sputter Deposition of Zinc Oxide

NASA Astrophysics Data System (ADS)

Xiao, Nan

2013-01-01

Development of thin film transistors (TFTs) with conventional channel layer materials, such as amorphous silicon (a-Si) and polysilicon (poly-Si), has been extensively investigated. A-Si TFT currently serves the large flat panel industry; however advanced display products are demanding better TFT performance because of the associated low electron mobility of a-Si. This has motivated interest in semiconducting metal oxides, such as Zinc Oxide (ZnO), for TFT backplanes. This work involves the fabrication and characterization of TFTs using ZnO deposited by sputtering. An overview of the process details and results from recently fabricated TFTs following a full-factorial designed experiment will be presented. Material characterization and analysis of electrical results will be described. The investigated process variables were the gate dielectric and ZnO sputtering process parameters including power density and oxygen partial pressure. Electrical results showed clear differences in treatment combinations, with certain I-V characteristics demonstrating superior performance to preliminary work. A study of device stability will also be discussed.

Projection display technologies for the new millennium

NASA Astrophysics Data System (ADS)

Kahn, Frederic J.

2000-04-01

Although analog CRTs continue to enable most of the world's electronic projection displays such as US consumer rear projection televisions, discrete pixel (digital) active matrix LCD and DLP reflective mirror array projectors have rapidly created large nonconsumer markets--primarily for business. Recent advances in image quality, compactness and cost effectiveness of digital projectors have the potential to revolutionize major consumer and entertainment markets as well. Digital penetration of the mainstream consumer projection TV market will begin in the hear 2000. By 2005 digital projection HDTVs could take the major share of the consumer HDTV projection market. Digital projection is expected to dominate both the consumer HDTV and the cinema market by 2010, resulting in potential shipments for all projection markets exceeding 10 M units per year. Digital projection is improving at a rate 10X faster than analog CRT projectors and 5X faster than PDP flat panels. Continued rapid improvement of digital projection is expected due to its relative immaturity and due to the wide diversity of technological improvements being pursued. Key technology enablers are the imaging panels, light sources and micro-optics. Market shares of single panel projectors, MEMs panels, LCOS panels and low T p-Si TFT LCD panel variants are expected to increase.

Improved electrical performance and bias stability of solution-processed active bilayer structure of indium zinc oxide based TFT.

PubMed

Seo, Jin-Suk; Bae, Byeong-Soo

2014-09-10

We fabricated active single- and bilayer structure thin film transistors (TFTs) with aluminum or gallium doped (IZO:Al or IZO:Ga) and undoped indium zinc oxide (IZO) thin film layers using an aqueous solution process. The electrical performance and bias stability of these active single- and bilayer structure TFTs were investigated and compared to reveal the effects of Al/Gal doping and bilayer structure. The single-layer structure IZO TFT shows a high mobility of 19 cm(2)/V · s with a poor positive bias stability (PBS) of ΔVT + 3.4 V. However, Al/Ga doped in IZO TFT reduced mobility to 8.5-9.9 cm(2)/V · s but improved PBS to ΔVT + 1.6-1.7 V due to the reduction of oxygen vacancy. Thus, it is found the bilayer structure TFTs with a combination of bottom- and top-layer compositions modify both the mobility and bias stability of the TFTs to be optimized. The bilayer structure TFT with an IZO:X bottom layer possess high mobility and an IZO bottom layer improves the PBS.

Window-assisted nanosphere lithography for vacuum micro-nano-electronics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Nannan; Institute of Electronic Engineering, Chinese Academy of Engineering Physics, Mianyang, 621900; Pang, Shucai

2015-04-15

Development of vacuum micro-nano-electronics is quite important for combining the advantages of vacuum tubes and solid-state devices but limited by the prevailing fabricating techniques which are expensive, time consuming and low-throughput. In this work, window-assisted nanosphere lithography (NSL) technique was proposed and enabled the low-cost and high-efficiency fabrication of nanostructures for vacuum micro-nano-electronic devices, thus allowing potential applications in many areas. As a demonstration, we fabricated high-density field emitter arrays which can be used as cold cathodes in vacuum micro-nano-electronic devices by using the window-assisted NSL technique. The details of the fabricating process have been investigated. This work provided amore » new and feasible idea for fabricating nanostructure arrays for vacuum micro-nano-electronic devices, which would spawn the development of vacuum micro-nano-electronics.« less

Involvement of concentrative nucleoside transporter 1 in intestinal absorption of trifluorothymidine, a novel antitumor nucleoside, in rats.

PubMed

Okayama, Takashige; Yoshisue, Kunihiro; Kuwata, Keizo; Komuro, Masahito; Ohta, Shigeru; Nagayama, Sekio

2012-02-01

ααα-Trifluorothymidine (TFT), an anticancer nucleoside analog, is a potent thymidylate synthase inhibitor. TFT exerts its antitumor activity primarily by inducing DNA fragmentation after incorporation of the triphosphate form of TFT into the DNA. Although an oral combination of TFT and a thymidine phosphorylase inhibitor has been clinically developed, there is little information regarding TFT absorption. Therefore, we investigated TFT absorption in the rat small intestine. After oral administration of TFT in rats, more than 75% of the TFT was absorbed. To identify the uptake transport system, uptake studies were conducted by using everted sacs prepared from rat small intestines. TFT uptake was saturable, significantly reduced under Na(+)-free conditions, and strongly inhibited by the addition of an endogenous pyrimidine nucleoside. From these results, we suggested the involvement of concentrative nucleoside transporters (CNTs) in TFT absorption into rat small intestine. In rat small intestines, the mRNAs coding for rat CNT1 (rCNT1) and rCNT2, but not for rCNT3, were predominantly expressed. To investigate the roles of rCNT1 and rCNT2 in TFT uptake, we conducted uptake assays by using Xenopus laevis oocytes injected with rCNT1 complementary RNA (cRNA) and rCNT2 cRNA. TFT uptake by X. laevis oocytes injected with rCNT1 cRNA, and not rCNT2 cRNA, was significantly greater than that by water-injected oocytes. In addition, in situ single-pass perfusion experiments performed using rat jejunum regions showed that thymidine, a substrate for CNT1, strongly inhibited TFT uptake. In conclusion, TFT is absorbed via rCNT1 in the intestinal lumen in rats.

Optimal Control of Shock Wave Turbulent Boundary Layer Interactions Using Micro-Array Actuation

NASA Technical Reports Server (NTRS)

Anderson, Bernhard H.; Tinapple, Jon; Surber, Lewis

2006-01-01

The intent of this study on micro-array flow control is to demonstrate the viability and economy of Response Surface Methodology (RSM) to determine optimal designs of micro-array actuation for controlling the shock wave turbulent boundary layer interactions within supersonic inlets and compare these concepts to conventional bleed performance. The term micro-array refers to micro-actuator arrays which have heights of 25 to 40 percent of the undisturbed supersonic boundary layer thickness. This study covers optimal control of shock wave turbulent boundary layer interactions using standard micro-vane, tapered micro-vane, and standard micro-ramp arrays at a free stream Mach number of 2.0. The effectiveness of the three micro-array devices was tested using a shock pressure rise induced by the 10 shock generator, which was sufficiently strong as to separate the turbulent supersonic boundary layer. The overall design purpose of the micro-arrays was to alter the properties of the supersonic boundary layer by introducing a cascade of counter-rotating micro-vortices in the near wall region. In this manner, the impact of the shock wave boundary layer (SWBL) interaction on the main flow field was minimized without boundary bleed.

Processing and characterization of high resolution GaN/InGaN LED arrays at 10 micron pitch for micro display applications

NASA Astrophysics Data System (ADS)

Dupré, Ludovic; Marra, Marjorie; Verney, Valentin; Aventurier, Bernard; Henry, Franck; Olivier, François; Tirano, Sauveur; Daami, Anis; Templier, François

2017-02-01

We report the fabrication process and characterization of high resolution 873 x 500 pixels emissive arrays based on blue or green GaN/InGaN light emitting diodes (LEDs) at a reduced pixel pitch of 10 μm. A self-aligned process along with a combination of damascene metallization steps is presented as the key to create a common cathode which is expected to provide good thermal dissipation and prevent voltage drops between center and side of the micro LED matrix. We will discuss the challenges of a self-aligned technology related to the choice of a good P contact metal and will present our solutions for the realization of the metallic interconnections between the GaN contacts and the higher levels of metallization at such a small pixel pitch. Enhanced control of each technological step allows scalability of the process up to 4 inch LED wafers and production of high quality LED arrays. The very high brightness (up to 107 cd.m-2) and good external quantum efficiency (EQE) of the resulting device make these kind of micro displays suitable for augmented reality or head up display applications.

Spatial distribution of structural defects in Cz-seeded directionally solidified silicon ingots: An etch pit study

NASA Astrophysics Data System (ADS)

Lantreibecq, A.; Legros, M.; Plassat, N.; Monchoux, J. P.; Pihan, E.

2018-02-01

The PV properties of wafers processed from Cz-seeded directionally solidified silicon ingots suffer from variable structural defects. In this study, we draw an overview on the types of structural defects encountered in the specific case of full 〈1 0 0〉 oriented growth. We found micro twins, background dislocations, and subgrains boundaries. We discuss the possible links between thermomechanical stresses and growth processes with spatial evolution of both background dislocation densities and subgrain boundaries length.

Sputtered boron indium oxide thin-film transistors

NASA Astrophysics Data System (ADS)

Stewart, Kevin A.; Gouliouk, Vasily; Keszler, Douglas A.; Wager, John F.

2017-11-01

Boron indium oxide (BIO) is studied for thin-film transistor (TFT) channel layer applications. Sputtered BIO thin films exhibit an amorphous phase over a wide range of B2O3/In2O3 ratios and remain amorphous up to 500 °C. The band gap decreases linearly with decreasing boron content, whereas device performance generally improves with decreasing boron content. The best amorphous BIO TFT exhibits a field-effect mobility of 10 cm2 V-1 s-1, turn-on voltage of 2.5 V, and sub-threshold swing of 0.72 V/dec. Decreasing the boron content to 12.5% leads to a polycrystalline phase, but further increases the mobility up to 20-40 cm2 V-1 s-1. TCAD simulation results suggest that the reason for higher performance after increasing the anneal temperature from 200 to 400 °C is due to a lower defect density in the sub-bandgap region of the BIO channel layer.

No strategy is evolutionarily stable in the repeated prisoner's dilemma.

PubMed

Lorberbaum, J

1994-05-21

Following the influential work of Axelrod, the repeated Prisoner's Dilemma game has become the theoretical gold standard for understanding the evolution of co-operative behavior among unrelated individuals. Using the game, several authors have found that a reciprocal strategy known as Tit for Tat (TFT) has done quite well in a wide range of environments. TFT strategists start out co-operating and then do what the other player did on the previous move. Despite the success of TFT and similar strategies in experimental studies of the game, Boyd & Lorberbaum (1987, Nature, Lond. 327, 58) have shown that no pure strategy, including TFT, is evolutionarily stable in the sense that each can be invaded by the joint effect of two invading strategies when long-term interaction occurs in the repeated game and future moves are discounted. Farrell & Ware (1989, Theor. Popul. Biol. 36, 161) have since extended these results to include finite mixes of pure strategies as well. Here, it is proven that no strategy is evolutionarily stable when long-term relationships are maintained in the repeated Prisoner's Dilemma and future moves are discounted. Namely, it is shown each completely probabilistic strategy (i.e. one that both co-operates and defects with positive probability after every sequence of behavior) may be invaded by a single deviant strategy. This completes the proof started by Boyd and Lorberbaum and extended by Farrell and Ware. This paper goes on to prove that no reactive strategy with a memory restricted to the opponent's preceding move is evolutionarily stable when there is no discounting of future moves. This is true despite the success of a more forgiving variant of TFT called GTFT in a recent tournament among reactive strategies conducted by Nowak & Sigmund (1992, Nature 355, 250) where future moves were not discounted. GTFT, for example, may be invaded by a pair of reactive mutants. Since no strategy is evolutionarily stable when future moves are discounted in the repeated game, the restriction of strategy types to those actually maintained by mutation and phenotypic and environmental variability in natural populations may be the key to understanding the evolution of co-operation. However, the result presented here that the somewhat realistic reactive strategies are also not evolutionarily stable at least in the non-discounted game suggests something else may be going on. For one, the proof that no reactive strategy is evolutionarily stable ironically shows the robustness of TFT-like strategies.(ABSTRACT TRUNCATED AT 400 WORDS)

Defect-induced infrared electroluminescence from radial GaInP/AlGaInP quantum well nanowire array light- emitting diodes

NASA Astrophysics Data System (ADS)

Hussain, Laiq; Karimi, Mohammad; Berg, Alexander; Jain, Vishal; Borgström, Magnus T.; Gustafsson, Anders; Samuelson, Lars; Pettersson, Håkan

2017-12-01

Radial GaInP/AlGaInP nanowire array light-emitting diodes (LEDs) are promising candidates for novel high-efficiency solid state lighting due to their potentially large strain-free active emission volumes compared to planar LEDs. Moreover, by proper tuning of the diameter of the nanowires, the fraction of emitted light extracted can be significantly enhanced compared to that of planar LEDs. Reports so far on radial growth of nanowire LED structures, however, still point to significant challenges related to obtaining defect-free radial heterostructures. In this work, we present evidence of optically active growth-induced defects in a fairly broad energy range in vertically processed radial GaInP/AlGaInP quantum well nanowire array LEDs using a variety of complementary experimental techniques. In particular, we demonstrate strong infrared electroluminescence in a spectral range centred around 1 eV (1.2 μm) in addition to the expected red light emission from the quantum well. Spatially resolved cathodoluminescence studies reveal a patchy red light emission with clear spectral features along the NWs, most likely induced by variations in QW thickness, composition and barriers. Dark areas are attributed to infrared emission generated by competing defect-assisted radiative transitions, or to trapping mechanisms involving non-radiative recombination processes. Possible origins of the defects are discussed.

High density pixel array and laser micro-milling method for fabricating array

NASA Technical Reports Server (NTRS)

McFall, James Earl (Inventor); Wiener-Avnear, Eliezer (Inventor)

2003-01-01

A pixel array device is fabricated by a laser micro-milling method under strict process control conditions. The device has an array of pixels bonded together with an adhesive filling the grooves between adjacent pixels. The array is fabricated by moving a substrate relative to a laser beam of predetermined intensity at a controlled, constant velocity along a predetermined path defining a set of grooves between adjacent pixels so that a predetermined laser flux per unit area is applied to the material, and repeating the movement for a plurality of passes of the laser beam until the grooves are ablated to a desired depth. The substrate is of an ultrasonic transducer material in one example for fabrication of a 2D ultrasonic phase array transducer. A substrate of phosphor material is used to fabricate an X-ray focal plane array detector.

A Furan-Thiophene-Based Quinoidal Compound: A New Class of Solution-Processable High-Performance n-Type Organic Semiconductor.

PubMed

Xiong, Yu; Tao, Jingwei; Wang, Ruihao; Qiao, Xiaolan; Yang, Xiaodi; Wang, Deliang; Wu, Hongzhuo; Li, Hongxiang

2016-07-01

The furan-thiophene-based quinoidal organic semiconductor, TFT-CN, is designed and synthesized. TFT-CN displays a high electron mobility of 7.7 cm(2) V(-1) s(-1) , two orders of magnitude higher than the corresponding thiophene-based derivative. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Trifluorothymidine exhibits potent antitumor activity via the induction of DNA double-strand breaks.

PubMed

Suzuki, Norihiko; Nakagawa, Fumio; Nukatsuka, Mamoru; Fukushima, Masakazu

2011-05-01

TAS-102 is an oral anticancer drug composed of trifluorothymidine (TFT) and TPI (an inhibitor of thymidine phosphorylase that strongly inhibits the biodegradation of TFT). Similar to 5-fluorouracil (5FU) and 5-fluoro-2'-deoxyuridine (FdUrd), TFT also inhibits thymidylate synthase (TS), a rate-limiting enzyme of DNA biosynthesis, and is incorporated into DNA. TFT exhibits an anticancer effect on colorectal cancer cells that have acquired 5FU and/or FdUrd resistance as a result of the overexpression of TS. Therefore, we examined the mode of action of TFT-induced DNA damage after its incorporation into DNA. When HeLa cells were treated with TFT, the number of ring-open aldehyde forms at apurinic/apyrimidinic sites increased in a dose-dependent manner, although we previously reported that no detectable excisions of TFT paired to adenine were observed using uracil DNA glycosylases, thymine DNA glycosylase or methyl-CpG binding domain 4 and HeLa whole cell extracts. To investigate the functional mechanism of TFT-induced DNA damage, we measured the phosphorylation of ATR, ATM, BRCA2, chk1 and chk2 in nuclear extracts of HeLa cells after 0, 24, 48 or 72 h of exposure to an IC(50) concentration of TFT, FdUrd or 5FU using Western blot analysis or an enzyme-linked immunosorbent assay (ELISA). Unlike FdUrd and 5FU, TFT resulted in an earlier phosphorylation of ATR and chk1 proteins after only 24 h of exposure, while phosphorylated ATM, BRCA2 and chk2 proteins were detected after more than 48 h of exposure to TFT. These results suggest that TFT causes single-strand breaks followed by double-strand breaks in the DNA of TFT-treated cells. TFT (as TAS-102) showed a more potent antitumor activity than oral 5FU on CO-3 colon cancer xenografts in mice, and such antitumor potency was supported by the increased number of double-strand breaks occurring after single-strand breaks in the DNA of the TFT-treated tumors. These results suggest that TFT causes single-strand breaks after its incorporation into DNA followed by double-strand breaks, resulting in DNA damage. This effect of TFT on DNA may explain its potent anticancer activity in cancer therapy.

Trifluorothymidine exhibits potent antitumor activity via the induction of DNA double-strand breaks

PubMed Central

SUZUKI, NORIHIKO; NAKAGAWA, FUMIO; NUKATSUKA, MAMORU; FUKUSHIMA, MASAKAZU

2011-01-01

TAS-102 is an oral anticancer drug composed of trifluorothymidine (TFT) and TPI (an inhibitor of thymidine phosphorylase that strongly inhibits the biodegradation of TFT). Similar to 5-fluorouracil (5FU) and 5-fluoro-2′-deoxyuridine (FdUrd), TFT also inhibits thymidylate synthase (TS), a rate-limiting enzyme of DNA biosynthesis, and is incorporated into DNA. TFT exhibits an anticancer effect on colorectal cancer cells that have acquired 5FU and/or FdUrd resistance as a result of the overexpression of TS. Therefore, we examined the mode of action of TFT-induced DNA damage after its incorporation into DNA. When HeLa cells were treated with TFT, the number of ring-open aldehyde forms at apurinic/apyrimidinic sites increased in a dose-dependent manner, although we previously reported that no detectable excisions of TFT paired to adenine were observed using uracil DNA glycosylases, thymine DNA glycosylase or methyl-CpG binding domain 4 and HeLa whole cell extracts. To investigate the functional mechanism of TFT-induced DNA damage, we measured the phosphorylation of ATR, ATM, BRCA2, chk1 and chk2 in nuclear extracts of HeLa cells after 0, 24, 48 or 72 h of exposure to an IC50 concentration of TFT, FdUrd or 5FU using Western blot analysis or an enzyme-linked immunosorbent assay (ELISA). Unlike FdUrd and 5FU, TFT resulted in an earlier phosphorylation of ATR and chk1 proteins after only 24 h of exposure, while phosphorylated ATM, BRCA2 and chk2 proteins were detected after more than 48 h of exposure to TFT. These results suggest that TFT causes single-strand breaks followed by double-strand breaks in the DNA of TFT-treated cells. TFT (as TAS-102) showed a more potent antitumor activity than oral 5FU on CO-3 colon cancer xenografts in mice, and such antitumor potency was supported by the increased number of double-strand breaks occurring after single-strand breaks in the DNA of the TFT-treated tumors. These results suggest that TFT causes single-strand breaks after its incorporation into DNA followed by double-strand breaks, resulting in DNA damage. This effect of TFT on DNA may explain its potent anticancer activity in cancer therapy. PMID:22977515

Development of an automation technique for the establishment of functional lipid bilayer arrays

NASA Astrophysics Data System (ADS)

Hansen, J. S.; Perry, M.; Vogel, J.; Vissing, T.; Hansen, C. R.; Geschke, O.; Emnéus, J.; Nielsen, C. H.

2009-02-01

In the present work, a technique for establishing multiple black lipid membranes (BLMs) in arrays of micro structured ethylene tetrafluoroethylene (ETFE) films, and supported by a micro porous material was developed. Rectangular 8 × 8 arrays with apertures having diameters of 301 ± 5 µm were fabricated in ETFE Teflon film by laser ablation using a carbon dioxide laser. Multiple lipid membranes could be formed across the micro structured 8 × 8 array ETFE partitions. Success rates for the establishment of cellulose-supported BLMs across the multiple aperture arrays were above 95%. However, the time course of the membrane thinning process was found to vary considerably between multiple aperture bilayer experiments. An airbrush partition pretreatment technique was developed to increase the reproducibility of the multiple lipid bilayers formation during the time course from the establishment of the lipid membranes to the formation of bilayers. The results showed that multiple lipid bilayers could be reproducible formed across the airbrush-pretreated 8 × 8 rectangular arrays. The ionophoric peptide valinomycin was incorporated into established membrane arrays, resulting in ionic currents that could be effectively blocked by tetraethylammonium. This shows that functional bimolecular lipid membranes were established, and furthermore outlines that the established lipid membrane arrays could host functional membrane-spanning molecules.

Solving the integration problem of one transistor one memristor architecture with a Bi-layer IGZO film through synchronous process

NASA Astrophysics Data System (ADS)

Chang, Che-Chia; Liu, Po-Tsun; Chien, Chen-Yu; Fan, Yang-Shun

2018-04-01

This study demonstrates the integration of a thin film transistor (TFT) and resistive random-access memory (RRAM) to form a one-transistor-one-resistor (1T1R) configuration. With the concept of the current conducting direction in RRAM and TFT, a triple-layer stack design of Pt/InGaZnO/Al2O3 is proposed for both the switching layer of RRAM and the channel layer of TFT. This proposal decreases the complexity of fabrication and the numbers of photomasks required. Also, the robust endurance and stable retention characteristics are exhibited by the 1T1R architecture for promising applications in memory-embedded flat panel displays.

High-performance low-cost back-channel-etch amorphous gallium-indium-zinc oxide thin-film transistors by curing and passivation of the damaged back channel.

PubMed

Park, Jae Chul; Ahn, Seung-Eon; Lee, Ho-Nyeon

2013-12-11

High-performance, low-cost amorphous gallium-indium-zinc oxide (a-GIZO) thin-film-transistor (TFT) technology is required for the next generation of active-matrix organic light-emitting diodes. A back-channel-etch structure is the most appropriate device structure for high-performance, low-cost a-GIZO TFT technology. However, channel damage due to source/drain etching and passivation-layer deposition has been a critical issue. To solve this problem, the present work focuses on overall back-channel processes, such as back-channel N2O plasma treatment, SiOx passivation deposition, and final thermal annealing. This work has revealed the dependence of a-GIZO TFT characteristics on the N2O plasma radio-frequency (RF) power and frequency, the SiH4 flow rate in the SiOx deposition process, and the final annealing temperature. On the basis of these results, a high-performance a-GIZO TFT with a field-effect mobility of 35.7 cm(2) V(-1) s(-1), a subthreshold swing of 185 mV dec(-1), a switching ratio exceeding 10(7), and a satisfactory reliability was successfully fabricated. The technology developed in this work can be realized using the existing facilities of active-matrix liquid-crystal display industries.

Micro-hole array fluorescent sensor based on AC-Dielectrophoresis (DEP) for simultaneous analysis of nano-molecules

NASA Astrophysics Data System (ADS)

Kim, Hye Jin; Kang, Dong-Hoon; Lee, Eunji; Hwang, Kyo Seon; Shin, Hyun-Joon; Kim, Jinsik

2018-02-01

We propose a simple fluorescent bio-chip based on two types of alternative current-dielectrophoretic (AC-DEP) force, attractive (positive DEP) and repulsive (negative DEP) force, for simultaneous nano-molecules analysis. Various radius of micro-holes on the bio-chip are designed to apply the different AC-DEP forces, and the nano-molecules are concentrated inside the micro-hole arrays according to the intensity of the DEP force. The bio-chip was fabricated by Micro Electro Mechanical system (MEMS) technique, and was composed of two layers; a SiO2 layer and Ta/Pt layer were accomplished for an insulation layer and a top electrode with micro-hole arrays to apply electric fields for DEP force, respectively. Each SiO2 and Ta/Pt layers were deposited by thermal oxidation and sputtering, and micro-hole arrays were fabricated with Inductively Coupled Plasma (ICP) etching process. For generation of each positive and negative DEP at micro-holes, we applied two types of sine-wave AC voltage with different frequency range alternately. The intensity of the DEP force was controlled by the radius of the micro-hole and size of nano-molecule, and calculated with COMSOL multi-physics. Three types of nano-molecules labelled with different fluorescent dye were used and the intensity of nano-molecules was examined by the fluorescent optical analysis after applying the DEP force. By analyzing the fluorescent intensities of the nano-molecules, we verify the various nano-molecules in analyte are located successfully inside corresponding micro-holes with different radius according to their size.

Numerical simulation and experimental research on interaction of micro-defects and laser ultrasonic signal

NASA Astrophysics Data System (ADS)

Guo, Hualing; Zheng, Bin; Liu, Hui

2017-11-01

In the present research, the mechanism governing the interaction between laser-generated ultrasonic wave and the micro-defects on an aluminum plate has been studied by virtue of numerical simulation as well as practical experiments. Simulation results indicate that broadband ultrasonic waves are caused mainly by surface waves, and that the surface waves produced by micro-defects could be utilized for the detection of micro-defects because these waves reflect as much information of the defects as possible. In the research, a laser-generated ultrasonic wave testing system with a surface wave probe has been established for the detection of micro-defects, and the surface waves produced by the defects with different depths on an aluminum plate have been tested by using the system. The interaction between defect depth and the maximum amplitude of the surface wave and that between defect depth and the center frequency of the surface wave have also been analyzed in detail. Research results indicate that, when the defect depth is less than half of the wavelength of the surface wave, the maximum amplitude and the center frequency of the surface wave are in linear proportion to the defect depth. Sound consistency of experimental results with theoretical simulation indicates that the system as established in the present research could be adopted for the quantitative detection of micro-defects.

Correlation between structural and opto-electronic characteristics of crystalline Si microhole arrays for photonic light management

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sontheimer, Tobias, E-mail: tobias.sontheimer@helmholtz-berlin.de; Schnegg, Alexander; Lips, Klaus

2013-11-07

By employing electron paramagnetic resonance spectroscopy, transmission electron microscopy, and optical measurements, we systematically correlate the structural and optical properties with the deep-level defect characteristics of various tailored periodic Si microhole arrays, which are manufactured in an easily scalable and versatile process on nanoimprinted sol-gel coated glass. While tapered microhole arrays in a structured base layer are characterized by partly nanocrystalline features, poor electronic quality with a defect concentration of 10{sup 17} cm{sup −3} and a high optical sub-band gap absorption, planar polycrystalline Si layers perforated with periodic arrays of tapered microholes are composed of a compact crystalline structure and amore » defect concentration in the low 10{sup 16} cm{sup −3} regime. The low defect concentration is equivalent to the one in planar state-of-the-art solid phase crystallized Si films and correlates with a low optical sub-band gap absorption. By complementing the experimental characterization with 3-dimensional finite element simulations, we provide the basis for a computer-aided approach for the low-cost fabrication of novel high-quality structures on large areas featuring tailored opto-electronic properties.« less

Method for formation of thin film transistors on plastic substrates

DOEpatents

Carey, Paul G.; Smith, Patrick M.; Sigmon, Thomas W.; Aceves, Randy C.

1998-10-06

A process for formation of thin film transistors (TFTs) on plastic substrates replaces standard thin film transistor fabrication techniques, and uses sufficiently lower processing temperatures so that inexpensive plastic substrates may be used in place of standard glass, quartz, and silicon wafer-based substrates. The process relies on techniques for depositing semiconductors, dielectrics, and metals at low temperatures; crystallizing and doping semiconductor layers in the TFT with a pulsed energy source; and creating top-gate self-aligned as well as back-gate TFT structures. The process enables the fabrication of amorphous and polycrystalline channel silicon TFTs at temperatures sufficiently low to prevent damage to plastic substrates. The process has use in large area low cost electronics, such as flat panel displays and portable electronics.

Micro heat barrier

DOEpatents

Marshall, Albert C.; Kravitz, Stanley H.; Tigges, Chris P.; Vawter, Gregory A.

2003-08-12

A highly effective, micron-scale micro heat barrier structure and process for manufacturing a micro heat barrier based on semiconductor and/or MEMS fabrication techniques. The micro heat barrier has an array of non-metallic, freestanding microsupports with a height less than 100 microns, attached to a substrate. An infrared reflective membrane (e.g., 1 micron gold) can be supported by the array of microsupports to provide radiation shielding. The micro heat barrier can be evacuated to eliminate gas phase heat conduction and convection. Semi-isotropic, reactive ion plasma etching can be used to create a microspike having a cusp-like shape with a sharp, pointed tip (<0.1 micron), to minimize the tip's contact area. A heat source can be placed directly on the microspikes. The micro heat barrier can have an apparent thermal conductivity in the range of 10.sup.-6 to 10.sup.-7 W/m-K. Multiple layers of reflective membranes can be used to increase thermal resistance.

Biological treatment of thin-film transistor liquid crystal display (TFT-LCD) wastewater.

PubMed

Lei, C N; Whang, L M; Lin, H L

2008-01-01

The amount of pollutants produced during manufacturing processes of TFT-LCD (thin-film transistor liquid crystal display) substantially increases due to an increasing production of the opto-electronic industry in Taiwan. The total amount of wastewater from TFT-LCD manufacturing plants is expected to exceed 200,000 CMD in the near future. Typically, organic solvents used in TFT-LCD manufacturing processes account for more than 33% of the total TFT-LCD wastewater. The main components of these organic solvents are composed of the stripper (dimethyl sulphoxide (DMSO) and monoethanolamine (MEA)), developer (tetra-methyl ammonium hydroxide (TMAH)) and chelating agents. These compounds are recognized as non-or slow-biodegradable organic compounds and little information is available regarding their biological treatability. In this study, the performance of an A/O SBR (anoxic/oxic sequencing batch reactor) treating synthetic TFT-LCD wastewater was evaluated. The long-term experimental results indicated that the A/O SBR was able to achieve stable and satisfactory removal performance for DMSO, MEA and TMAH at influent concentrations of 430, 800, and 190 mg/L, respectively. The removal efficiencies for all three compounds examined were more than 99%. In addition, batch tests were conducted to study the degradation kinetics of DMSO, MEA, and TMAH under aerobic, anoxic, and anaerobic conditions, respectively. The organic substrate of batch tests conducted included 400 mg/L of DMSO, 250 mg/L of MEA, and 120 mg/L of TMAH. For DMSO, specific DMSO degradation rates under aerobic and anoxic conditions were both lower than 4 mg DMSO/g VSS-hr. Under anaerobic conditions, the specific DMSO degradation rate was estimated to be 14 mg DMSO/g VSS-hr, which was much higher than those obtained under aerobic and anoxic conditions. The optimum specific MEA and TMAH degradation rates were obtained under aerobic conditions with values of 26.5 mg MEA/g VSS-hr and 17.3 mg TMAH/g VSS-hr, respectively. Compared to aerobic conditions, anaerobic biodegradation of MEA and TMAH was much less significant with values of 5.6 mg MEA/g VSS-hr and 0 mg TMAH/g VSS-hr, respectively. In summary, biological treatment of TFT-LCD wastewater containing DMSO, MEA, and TMAH is feasible, but appropriate conditions for optimum biodegradation of DMSO, MEA, and TMAH are crucial and require carefully operational consideration. Copyright IWA Publishing 2008.

JPRS Report, Science & Technology, China, High-Performance Computer Systems

DTIC Science & Technology

1992-10-28

microprocessor array The microprocessor array in the AP85 system is com- posed of 16 completely identical array element micro - processors . Each array element...microprocessors and capable of host machine reading and writing. The memory capacity of the array element micro - processors as a whole can be expanded...transmission functions to carry out data transmission from array element micro - processor to array element microprocessor, from array element

Analysis of current driving capability of pentacene TFTs for OLEDs

NASA Astrophysics Data System (ADS)

Ryu, Gi Seong; Byun, Hyun Sook; Xu, Yong Xian; Pyo, Kyung Soo; Choe, Ki Beom; Song, Chung Kun

2005-01-01

The flexible display and the application of Roll-To-Roll process is difficult because high temperature process of a-Si;H TFT and poly-Si TFT limited the use of plastic substrate. We proposed AMOLED using Pentacene TFT (OTFT) to fabricate flexible display. The first stage for OTFT application to OLED, we analyzed OTFT as driving device of OLED. The process performed on glass and plastic (PET) substrate that is coated ITO and PVP is used for gate insulator. The field effect mobility of the fabricated OTFT is 0.1~0.3cm2/V"sec and Ion/Ioff current ratio is 103~105. OLED is fabricated with two stories structure of TPD and Alq3, and we can observe the light at 5V by the naked eye. The wavelength of observed lights is 530nm ~550nm. We can confirm the driving of OLED due to OTFT using Test panel and observe OLED control by gate voltage of OTFT. Also, we verify designed structure and process, and make a demonstration fabricating 64 by 64 backplane based on Test panel.

Low-temperature fabrication of an HfO2 passivation layer for amorphous indium-gallium-zinc oxide thin film transistors using a solution process.

PubMed

Hong, Seonghwan; Park, Sung Pyo; Kim, Yeong-Gyu; Kang, Byung Ha; Na, Jae Won; Kim, Hyun Jae

2017-11-24

We report low-temperature solution processing of hafnium oxide (HfO 2 ) passivation layers for amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs). At 150 °C, the hafnium chloride (HfCl 4 ) precursor readily hydrolyzed in deionized (DI) water and transformed into an HfO 2 film. The fabricated HfO 2 passivation layer prevented any interaction between the back surface of an a-IGZO TFT and ambient gas. Moreover, diffused Hf 4+ in the back-channel layer of the a-IGZO TFT reduced the oxygen vacancy, which is the origin of the electrical instability in a-IGZO TFTs. Consequently, the a-IGZO TFT with the HfO 2 passivation layer exhibited improved stability, showing a decrease in the threshold voltage shift from 4.83 to 1.68 V under a positive bias stress test conducted over 10,000 s.

Xanthomonas euvesicatoria type III effector XopQ interacts with tomato and pepper 14-3-3 isoforms to suppress effector-triggered immunity.

PubMed

Teper, Doron; Salomon, Dor; Sunitha, Sukumaran; Kim, Jung-Gun; Mudgett, Mary Beth; Sessa, Guido

2014-01-01

Effector-triggered immunity (ETI) to host-adapted pathogens is associated with rapid cell death at the infection site. The plant-pathogenic bacterium Xanthomonas euvesicatoria (Xcv) interferes with plant cellular processes by injecting effector proteins into host cells through the type III secretion system. Here, we show that the Xcv effector XopQ suppresses cell death induced by components of the ETI-associated MAP kinase cascade MAPKKKα MEK2/SIPK and by several R/avr gene pairs. Inactivation of xopQ by insertional mutagenesis revealed that this effector inhibits ETI-associated cell death induced by avirulent Xcv in resistant pepper (Capsicum annuum), and enhances bacterial growth in resistant pepper and tomato (Solanum lycopersicum). Using protein-protein interaction studies in yeast (Saccharomyces cerevisiae) and in planta, we identified the tomato 14-3-3 isoform SlTFT4 and homologs from other plant species as XopQ interactors. A mutation in the putative 14-3-3 binding site of XopQ impaired interaction of the effector with CaTFT4 in yeast and its virulence function in planta. Consistent with a role in ETI, TFT4 mRNA abundance increased during the incompatible interaction of tomato and pepper with Xcv. Silencing of NbTFT4 in Nicotiana benthamiana significantly reduced cell death induced by MAPKKKα. In addition, silencing of CaTFT4 in pepper delayed the appearance of ETI-associated cell death and enhanced growth of virulent and avirulent Xcv, demonstrating the requirement of TFT4 for plant immunity to Xcv. Our results suggest that the XopQ virulence function is to suppress ETI and immunity-associated cell death by interacting with TFT4, which is an important component of ETI and a bona fide target of XopQ. © 2013 The Authors The Plant Journal © 2013 John Wiley & Sons Ltd.

Low temperature fabrication of CuxO thin-film transistors and investigation on the origin of low field effect mobility

NASA Astrophysics Data System (ADS)

Shijeesh, M. R.; Jayaraj, M. K.

2018-04-01

Cuprous (Cu2O) and cupric (CuO) oxide thin films have been deposited by radio frequency magnetron sputtering with two different oxygen partial pressures. The as-deposited copper oxide films were subjected to post-annealing at 300 °C for 30 min to improve the microstructural, morphological, and optical properties of thin films. Optical absorption studies revealed the existence of a large number of subgap states inside CuO films than Cu2O films. Cu2O and CuO thin film transistors (TFTs) were fabricated in an inverted staggered structure by using a post-annealed channel layer. The field effect mobility values of Cu2O and CuO TFTs were 5.20 × 10-4 cm2 V-1 s-1 and 2.33 × 10-4 cm2 V-1 s-1, respectively. The poor values of subthreshold swing, threshold voltage, and field effect mobility of the TFTs were due to the charge trap density at the copper oxide/dielectric interface as well as defect induced trap states originated from the oxygen vacancies inside the bulk copper oxide. In order to study the distribution of the trap states in the Cu2O and CuO active layer, the temperature dependent transfer characteristics of transistors in the temperature range between 310 K and 340 K were studied. The observed subgap states were found to be decreasing exponentially inside the bandgap, with CuO TFT showing higher subgap states than Cu2O TFT. The high-density hole trap states in the CuO channel are one of the plausible reasons for the lower mobility in CuO TFT than in Cu2O TFT. The origin of these subgap states was attributed to the impurities or oxygen vacancies present in the CuO channel layer.

Pulsed direct flame deposition and thermal annealing of transparent amorphous indium zinc oxide films as active layers in field effect transistors.

PubMed

Kilian, Daniel; Polster, Sebastian; Vogeler, Isabell; Jank, Michael P M; Frey, Lothar; Peukert, Wolfgang

2014-08-13

Indium-zinc oxide (IZO) films were deposited via flame spray pyrolysis (FSP) by pulsewise shooting a Si/SiO2 substrate directly into the combustion area of the flame. Based on UV-vis measurements of thin-films deposited on glass substrates, the optimal deposition parameters with respect to low haze values and film thicknesses of around 100 nm were determined. Thermal annealing of the deposited films at temperatures between 300 and 700 °C was carried out and staggered bottom gate thin-film transistors (TFT) were fabricated. The thin films were investigated by scanning electron microscopy, atomic force microscopy, X-ray diffraction, Fourier transformed infrared spectroscopy, and room-temperature photoluminescence measurements. The outcome of these investigations lead to two major requirements in order to implement a working TFT: (i) organic residues from the deposition process need to be removed and (ii) the net free charge carrier concentration has to be minimized by controlling the trap states in the semiconductor. The optimal annealing temperature was 300 °C as both requirements are fulfilled best in this case. This leads to field effect transistors with a low hysteresis, a saturation mobility of μSat = 0.1 cm(2)/(V s), a threshold voltage of Vth = -18.9 V, and an Ion/Ioff ratio on the order of 10(7). Depending on thermal treatment, the defect density changes significantly strongly influencing the transfer characteristics of the device.

Micro-Machined High-Frequency (80 MHz) PZT Thick Film Linear Arrays

PubMed Central

Zhou, Qifa; Wu, Dawei; Liu, Changgeng; Zhu, Benpeng; Djuth, Frank; Shung, K. Kirk

2010-01-01

This paper presents the development of a micro-machined high-frequency linear array using PZT piezoelectric thick films. The linear array has 32 elements with an element width of 24 μm and an element length of 4 mm. Array elements were fabricated by deep reactive ion etching of PZT thick films, which were prepared from spin-coating of PZT solgel composite. Detailed fabrication processes, especially PZT thick film etching conditions and a novel transferring-and-etching method, are presented and discussed. Array designs were evaluated by simulation. Experimental measurements show that the array had a center frequency of 80 MHz and a fractional bandwidth (−6 dB) of 60%. An insertion loss of −41 dB and adjacent element crosstalk of −21 dB were found at the center frequency. PMID:20889407

Compact self-aligning assemblies with refractive microlens arrays made by contactless embossing

NASA Astrophysics Data System (ADS)

Schulze, Jens; Ehrfeld, Wolfgang; Mueller, Holger; Picard, Antoni

1998-04-01

The hybrid integration of microlenses and arrays of microlenses in micro-optical systems is simplified using contactless embossing of microlenses (CEM) in combination with LIGA microfabrication. CEM is anew fabrication technique for the production of precise refractive microlens arrays. A high precision matrix of holes made by LIGA technique is used as a compression molding tool to form the microlenses. The tool is pressed onto a thermoplastic sample which is heated close to the glass transformation temperature of the material. The material bulges into the openings of the molding tool due to the applied pressure and forms lens-like spherical structures. The name refers to the fact that the surface of the microlens does not get in contact with the compression molding tool during the shaping process and optical quality of the surface is maintained. Microlenses and arrays of microlenses with lens diameters from 30 micrometers up to 700 micrometers and numerical aperture values of up to 0.25 have been fabricated in different materials. Cost-effectiveness in the production process, excellent optical performance and the feature of easy replication are the main advantages of this technique. The most promising feature of this method is the possibility to obtain self- aligned assemblies then can be further integrated into a micro-optical bench setup. The CEM fabrication method in combination with LIGA microfabrication considerably enhances the hybrid integration in micro-optical devices which results in a more cost-effective production of compact micro-opto-electro-mechanical systems.

Intentional defect array wafers: their practical use in semiconductor control and monitoring systems

NASA Astrophysics Data System (ADS)

Emami, Iraj; McIntyre, Michael; Retersdorf, Michael

2003-07-01

In the competitive world of semiconductor manufacturing today, control of the process and manufacturing equipment is paramount to success of the business. Consistent with the need for rapid development of process technology, is a need for development wiht respect to equipment control including defect metrology tools. Historical control methods for defect metrology tools included a raw count of defects detected on a characterized production or test wafer with little or not regard to the attributes of the detected defects. Over time, these characterized wafers degrade with multiple passes on the tools and handling requiring the tool owner to create and characterize new samples periodically. With the complex engineering software analysis systems used today, there is a strong reliance on the accuracy of defect size, location, and classification in order to provide the best value when correlating the in line to sort type of data. Intentional Defect Array (IDA) wafers were designed and manufacturered at International Sematech (ISMT) in Austin, Texas and is a product of collaboration between ISMT member companies and suppliers of advanced defect inspection equipment. These wafers provide the use with known defect types and sizes in predetermined locations across the entire wafer. The wafers are designed to incorporate several desired flows and use critical dimensions consistent with current and future technology nodes. This paper briefly describes the design of the IDA wafer and details many practical applications in the control of advanced defect inspection equipment.

Low Earth orbital atomic oxygen micrometeoroid, and debris interactions with photovoltaic arrays

NASA Technical Reports Server (NTRS)

Banks, Bruce A.; Rutledge, Sharon K.; Degroh, Kim K.

1991-01-01

Polyimide Kapton solar array blankets can be protected from atomic oxygen in low earth orbit if SiO sub x thin film coatings are applied to their surfaces. The useful lifetime of a blanket protected in this manner strongly depends on the number and size of defects in the protective coatings. Atomic oxygen degradation is dominated by undercutting at defects in protective coatings caused by substrate roughness and processing rather than micrometeoroid or debris impacts. Recent findings from the Long Duration Exposure Facility (LDEF) and ground based studies show that interactions between atomic oxygen and silicones may cause grazing and contamination problems which may lead to solar array degradation.

Effects of Ga:N addition on the electrical performance of zinc tin oxide thin film transistor by solution-processing.

PubMed

Ahn, Byung Du; Jeon, Hye Ji; Park, Jin-Seong

2014-06-25

This paper addressed the effect of gallium nitrate hydrate addition on thin film transistor (TFT) performance and positive bias stability of amorphous zinc tin oxide (ZTO) TFTs by solution processing, Further, the mechanisms responsible for chemical properties and electronic band structure are explored. A broad exothermic peak accompanied by weight loss appeared in the range from about 350 to 570 °C for the ZTO solution; the thermal reaction of the Ga-ZTO:N solution was completed at 520 °C. This is because the gallium nitrate hydrate precursor promoted the decomposition and dehydroxylation reaction for Zn(CH3COO)2·2H2O and/or SnCl2·2H2O precursors. The concentrations of carbon and chloride in gallium nitrate hydrate added ZTO films annealed at 400 °C have a lower value (C 0.65, Cl 0.65 at. %) compared with those of ZTO films (C 3.15, Cl 0.82 at. %). Absorption bands at 416, 1550, and 1350 cm(-1) for GaZTO:N films indicated the presence of ZnGa2O4, N-H, and N═O groups by Fourier transform infrared spectroscopy measurement, respectively. As a result, an inverted staggered Ga-ZTO:N TFT exhibited a mobility of 4.84 cm(2) V(-1) s(-1) in the saturation region, a subthreshold swing of 0.35 V/decade, and a threshold gate voltage (Vth) of 0.04 V. In addition, the instability of Vth values of the ZTO TFTs under positive bias stress conditions was suppressed by adding Ga and N from 13.6 to 3.17 V, which caused a reduction in the oxygen-related defects located near the conduction band.

Suppression of TFT leakage current effect on active matrix displays by employing a new circular switch

NASA Astrophysics Data System (ADS)

Lee, Jae-Hoon; Park, Hyun-Sang; Jeon, Jae-Hong; Han, Min-Koo

2008-03-01

We have proposed a new poly-Si TFT pixel, which can suppress TFT leakage current effect on active matrix organic diode (AMOLED) displays, by employing a new circular switching TFT and additional signal line for compensating the leakage current. When the leakage current of switching TFT is increased, the VGS of the current driving TFT in the proposed pixel is not altered by the variable data voltages due to the circular switching TFT. Our simulation results show that OLED current variation of the proposed pixel can be suppressed less than 3%, while that of conventional pixel exceeds 30%. The proposed pixel may be suitable to suppress the leakage current effect on AMOLED display.

Embossing of optical document security devices

NASA Astrophysics Data System (ADS)

Muke, Sani

2004-06-01

Embossing in the transparent window area of polymer banknotes, such as those seen on the Australian, New Zealand and Romanian currencies, have enormous potential for the development of novel optical security devices. The intaglio printing process can provide an efficient means for embossing of optical security structures such as micro lenses. Embossed micro lens arrays in the transparent window of a polymer banknote can be folded over a corresponding printed image array elsewhere on the note to reveal a series of moire magnified images. Analysis of samples of embossed micro lenses showed that the engraving side and impression side had a similar embossed profile. The embossed micro lens profiles were modelled using Optalix-LX commercial optical ray tracing software in order to determine the focal length of the lenses and compare with the focal length of desired embossed lenses. A fundamental understanding of how the polymer deforms during the embossing process is critical towards developing a micro lens embossing tool which can achieve the desired embossed micro lenses. This work also looks at extending the early research of the Intaglio Research Group (IRG) to better understand the embossibility of polymer substrates such as biaxially oriented polypropylene (BOPP).

Longitudinal in vivo evaluation of bone regeneration by combined measurement of multi-pinhole SPECT and micro-CT for tissue engineering

NASA Astrophysics Data System (ADS)

Lienemann, Philipp S.; Metzger, Stéphanie; Kiveliö, Anna-Sofia; Blanc, Alain; Papageorgiou, Panagiota; Astolfo, Alberto; Pinzer, Bernd R.; Cinelli, Paolo; Weber, Franz E.; Schibli, Roger; Béhé, Martin; Ehrbar, Martin

2015-05-01

Over the last decades, great strides were made in the development of novel implants for the treatment of bone defects. The increasing versatility and complexity of these implant designs request for concurrent advances in means to assess in vivo the course of induced bone formation in preclinical models. Since its discovery, micro-computed tomography (micro-CT) has excelled as powerful high-resolution technique for non-invasive assessment of newly formed bone tissue. However, micro-CT fails to provide spatiotemporal information on biological processes ongoing during bone regeneration. Conversely, due to the versatile applicability and cost-effectiveness, single photon emission computed tomography (SPECT) would be an ideal technique for assessing such biological processes with high sensitivity and for nuclear imaging comparably high resolution (<1 mm). Herein, we employ modular designed poly(ethylene glycol)-based hydrogels that release bone morphogenetic protein to guide the healing of critical sized calvarial bone defects. By combined in vivo longitudinal multi-pinhole SPECT and micro-CT evaluations we determine the spatiotemporal course of bone formation and remodeling within this synthetic hydrogel implant. End point evaluations by high resolution micro-CT and histological evaluation confirm the value of this approach to follow and optimize bone-inducing biomaterials.

Fabrication of Amorphous Indium Gallium Zinc Oxide Thin Film Transistor by using Focused Ion Beam

NASA Astrophysics Data System (ADS)

Zhu, Wencong

Compared with other transparent semiconductors, amorphous indium gallium zinc oxide (a-IGZO) has both good uniformity and high electron mobility, which make it as a good candidate for displays or large-scale transparent circuit. The goal of this research is to fabricate alpha-IGZO thin film transistor (TFT) with channel milled by focused ion beam (FIB). TFTs with different channel geometries can be achieved by applying different milling strategies, which facilitate modifying complex circuit. Technology Computer-Aided Design (TCAD) was also introduced to understand the effect of trapped charges on the device performance. The investigation of the trapped charge at IGZO/SiO2 interface was performed on the IGZO TFT on p-Silicon substrate with thermally grown SiO2 as dielectric. The subgap density-of-state model was used for the simulation, which includes conduction band-tail trap states and donor-like state in the subgap. The result shows that the de-trapping and donor-state ionization determine the interface trapped charge density at various gate biases. Simulation of IGZO TFT with FIB defined channel on the same substrate was also applied. The drain and source were connected intentionally during metal deposition and separated by FIB milling. Based on the simulation, the Ga ions in SiO2 introduced by the ion beam was drifted by gate bias and affects the saturation drain current. Both side channel and direct channel transparent IGZO TFTs were fabricated on the glass substrate with coated ITO. Higher ion energy (30 keV) was used to etch through the substrate between drain and source and form side channels at the corner of milled trench. Lower ion energy (16 keV) was applied to stop the milling inside IGZO thin film and direct channel between drain and source was created. Annealing after FIB milling removed the residual Ga ions and the devices show switch feature. Direct channel shows higher saturation drain current (~10-6 A) compared with side channel (~10-7 A) because of its shorter channel length and wider width, however, it also exhibit higher gate leakage current (>10-7 A) than side channel (<10-7 A) due to larger Ga ion implantation and diffusion region in SiO2 after annealing. Hysteresis window increase and positive VON shift were also observed due to the interface trap density increase and carrier density suppression both by Ga ions. Laser interference lithography was applied to define the IGZO active region, which gives more flexibility on TFT channel dimension and circuit modification. He-Cd laser with 325 nm wavelength was used to define 2D array of IGZO islands with period of 2.5 im. Logic gate array was designed and fabricated by combining this 2D array of IGZO islands and FIB direct channel milling. After annealing, device shows on-off feature, but high temperature (400 °C) release more free carrier and results in negative shift of VON. The row selection voltage was also introduced in the design of logic gate array to act as switch of input signals to each row separately. However, due to the long input signal sweeping time, the leakage current cannot be overlooked. The idea can be verified by AC or short pulse input signal.

Array Automated Assembly Task Low Cost Silicon Solar Array Project, Phase 2

NASA Technical Reports Server (NTRS)

Rhee, S. S.; Jones, G. T.; Allison, K. L.

1978-01-01

Progress in the development of solar cells and module process steps for low-cost solar arrays is reported. Specific topics covered include: (1) a system to automatically measure solar cell electrical performance parameters; (2) automation of wafer surface preparation, printing, and plating; (3) laser inspection of mechanical defects of solar cells; and (4) a silicon antireflection coating system. Two solar cell process steps, laser trimming and holing automation and spray-on dopant junction formation, are described.

Pulse Thermal Processing for Low Thermal Budget Integration of IGZO Thin Film Transistors

DOE PAGES

Noh, Joo Hyon; Joshi, Pooran C.; Kuruganti, Teja; ...

2014-11-26

Pulse thermal processing (PTP) has been explored for low thermal budget integration of indium gallium zinc oxide (IGZO) thin film transistors (TFTs). The IGZO TFTs are exposed to a broadband (0.2-1.4 m) arc lamp radiation spectrum with 100 pulses of 1 msec pulse width. The impact of radiant exposure power on the TFT performance was analyzed in terms of the switching characteristics and bias stress reliability characteristics, respectively. The PTP treated IGZO TFTs with power density of 3.95 kW/cm 2 and 0.1 sec total irradiation time showed comparable switching properties, at significantly lower thermal budget, to furnace annealed IGZO TFT.more » The typical field effect mobility FE, threshold voltage VT, and sub-threshold gate swing S.S were calculated to be 7.8 cm 2/ V s, 8.1 V, and 0.22 V/ decade, respectively. The observed performance shows promise for low thermal budget TFT integration on flexible substrates exploiting the large-area, scalable PTP technology.« less

Pulse Thermal Processing for Low Thermal Budget Integration of IGZO Thin Film Transistors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Noh, Joo Hyon; Joshi, Pooran C.; Kuruganti, Teja

Pulse thermal processing (PTP) has been explored for low thermal budget integration of indium gallium zinc oxide (IGZO) thin film transistors (TFTs). The IGZO TFTs are exposed to a broadband (0.2-1.4 m) arc lamp radiation spectrum with 100 pulses of 1 msec pulse width. The impact of radiant exposure power on the TFT performance was analyzed in terms of the switching characteristics and bias stress reliability characteristics, respectively. The PTP treated IGZO TFTs with power density of 3.95 kW/cm 2 and 0.1 sec total irradiation time showed comparable switching properties, at significantly lower thermal budget, to furnace annealed IGZO TFT.more » The typical field effect mobility FE, threshold voltage VT, and sub-threshold gate swing S.S were calculated to be 7.8 cm 2/ V s, 8.1 V, and 0.22 V/ decade, respectively. The observed performance shows promise for low thermal budget TFT integration on flexible substrates exploiting the large-area, scalable PTP technology.« less

Characteristics of Reduced Graphene Oxide Quantum Dots for a Flexible Memory Thin Film Transistor.

PubMed

Kim, Yo-Han; Lee, Eun Yeol; Lee, Hyun Ho; Seo, Tae Seok

2017-05-17

Reduced graphene oxide quantum dot (rGOQD) devices in formats of capacitor and thin film transistor (TFT) were demonstrated and examined as the first trial to achieve nonambipolar channel property. In addition, through a gold nanoparticle (Au NP) layer embedded between the rGOQD active channel and dielectric layer, memory capacitor and TFT performances were realized by capacitance-voltage (C-V) hysteresis and gate program, erase, and reprogram biases. First, capacitor structure of the rGOQD memory device was constructed to examine memory charging effect featured in hysteretic C-V behavior with a 30 nm dielectric layer of cross-linked poly(vinyl alcohol). For the intervening Au NP charging layer, self-assembled monolayer (SAM) formation of the Au NP was executed to utilize electrostatic interaction by a dip-coating process under ambient environments with a conformal fabrication uniformity. Second, the rGOQD memory TFT device was also constructed in the same format of the Au NPs SAMs on a flexible substrate. Characteristics of the rGOQD TFT output showed novel saturation curves unlike typical graphene-based TFTs. However, The rGOQD TFT device reveals relatively low on/off ratio of 10 1 and mobility of 5.005 cm 2 /V·s. For the memory capacitor, the flat-band voltage shift (ΔV FB ) was measured as 3.74 V for ±10 V sweep, and for the memory TFT, the threshold voltage shift (ΔV th ) by the Au NP charging was detected as 7.84 V. In summary, it was concluded that the rGOQD memory device could accomplish an ideal graphene-based memory performance, which could have provided a wide memory window and saturated output characteristics.

Application of multi-tone mask technology in photolithographic fabrication of color filter components in LCD

NASA Astrophysics Data System (ADS)

Takada, Yoshihiro; Fukui, Matoko; Sai, Tsunehiro

2008-11-01

Recent progresses in the photoresists and photolithography for LCD industry applications have been primarily driven by the following two factors: advancement in the material performances (high resolution, high contrast ratio, low dielectric constant) for higher display quality, and cost reduction in the fabrication process. Along with crucial demand for cost competitiveness by improving production efficiency, environmental consciousness has been a major priority at fabrication process design to minimize the amount of waste produced. Having said the above, integration of two or more fabrication processes into a single process by using multi-tone mask technology has been the interest of research, due to its obvious advantage of reducing fabrication processes and cost. For example, multi-tone mask technology application has been widely employed on the TFT side to reduce the different types of photomasks being used. Similar trend has been employed on the CF side as well, where application of multi-tone mask technology is being investigated to integrate fabrication of multiple CF micro-components into a single process. In this presentation, we demonstrate a new approach of fabricating photospacer and peripheral CF components (MVA protrusion, sub-photospacers) in a single integrated process through multi-tone mask technology.

Method for formation of thin film transistors on plastic substrates

DOEpatents

Carey, P.G.; Smith, P.M.; Sigmon, T.W.; Aceves, R.C.

1998-10-06

A process for formation of thin film transistors (TFTs) on plastic substrates replaces standard thin film transistor fabrication techniques, and uses sufficiently lower processing temperatures so that inexpensive plastic substrates may be used in place of standard glass, quartz, and silicon wafer-based substrates. The process relies on techniques for depositing semiconductors, dielectrics, and metals at low temperatures; crystallizing and doping semiconductor layers in the TFT with a pulsed energy source; and creating top-gate self-aligned as well as back-gate TFT structures. The process enables the fabrication of amorphous and polycrystalline channel silicon TFTs at temperatures sufficiently low to prevent damage to plastic substrates. The process has use in large area low cost electronics, such as flat panel displays and portable electronics. 5 figs.

Mode of action of trifluorothymidine (TFT) against DNA replication and repair enzymes.

PubMed

Suzuki, Norihiko; Emura, Tomohiro; Fukushima, Masakazu

2011-07-01

Trifluorothymidine (TFT) is well known to be converted to TFT-monophosphate by thymidine kinase and to inhibit thymidylate synthase. In addition, TFT-triphosphate (TFT-TP) is also incorporated into DNA, resulting in cytocidal effects. However, the precise mechanism of TFT-induced DNA damage is still unclear. Therefore, we investigated the modes of action of TFT against DNA replication and repair enzymes, as compared with those of 5FU and FdUrd. When HeLa cells were treated with TFT at a concentration of 1 µM (IC50 value), the concentration of TFT in the DNA was calculated as 62.2±0.9 pmol/1x106 cells for 4 h. On the other hand, following treatment of the cells with FdUrd (0.5 µM) and 5FU (10 µM) at their IC50 doses, the drug concentrations in the DNA were 7.53, and 0.17 pmol/1 x 10⁶ cells for 4 h, respectively. These results show the markedly greater degree of incorporation of TFT into the DNA of the HeLa cells compared with that of 5FU (approximately more than 300-fold for 4 h) or FdUrd (approximately more than 8-fold for 4 h). The primer extension assay demonstrated that TFT-TP was also incorporated into the T-sites of the growing DNA strand, however, it competed only weakly with thymidine triphosphate. The DNA glycosylase assay was performed using commercially available DNA glycosylase and fractionated HeLa cell extracts obtained by gel filtration. There was no detectable excision of the TFT pairing to adenine by uracil DNA glycosylase (UDG), thymine DNA glycosylase (TDG), methyl-CpG binding domain 4 (MBD4) or the fractionated HeLa cell extracts, however, TDG and MBD4 were able to excise the TFT pairing to guanine. Additional data indicate that small-interfering RNA-mediated knockdown of TDG or MBD4 significantly increased the resistance to the cytotoxic effects of FdUrd, but not to that of TFT. These studies show the greater degree of incorporation of TFT into the DNA than that of 5FU or FdUrd, and that such a high degree of incorporation of TFT residues into the DNA might be related to exhibit potent cytotoxic activity to be refractory to cleavage by these DNA glycosylases; thus, the DNA-directed cytotoxic effect of the compound is quite different from that of 5FU.

Transplantation of mature adipocyte-derived dedifferentiated fat cells into three-wall defects in the rat periodontium induces tissue regeneration.

PubMed

Suzuki, Daigo; Akita, Daisuke; Tsurumachi, Niina; Kano, Koichiro; Yamanaka, Katsuyuki; Kaneko, Tadashi; Kawano, Eisuke; Iguchi, Shinya; Toriumi, Taku; Arai, Yoshinori; Matsumoto, Taro; Sato, Shuichi; Honda, Masaki

2017-01-01

The transplantation of dedifferentiated fat (DFAT) cells in combination with poly(d,l-lactic-co-glycolic acid) (PLGA) scaffolds has previously been proven as an effective approach in promoting periodontal tissue regeneration in a rat fenestration defect model. The aim of this study was to assess the regenerative potential of DFAT cells in a rat model of three-wall periodontal bone defect. Three-wall bone defects were created bilaterally on the mesial side of rat maxillary first molars and were either left untreated or treated by implantation of PLGA scaffolds with DFAT cells or PLGA alone. Four weeks after surgery, the tissues were processed for micro-computed tomography (micro-CT) and histomorphometric examination. Micro-CT revealed that the PLGA/DFAT group had significantly higher rates of bone regeneration than the other groups, while histomorphometric analysis showed that the PLGA/DFAT group had significantly higher densities of collagen fiber bundles in acellular and cellular cementum than the PLGA group. Moreover, the results indicate that the placement of the PLGA scaffold prevented the downgrowth of the junctional epithelium. These findings suggest that DFAT cells contribute to tissue regeneration in three-wall periodontal defects, while PLGA provides space necessary for periodontal tissue restoration.

Mechanistic aspects of thioflavin-T self-aggregation and DNA binding: evidence for dimer attack on DNA grooves.

PubMed

Biancardi, A; Biver, T; Burgalassi, A; Mattonai, M; Secco, F; Venturini, M

2014-10-07

Thioflavin-T (TFT) is a fluorescent marker widely employed in biomedical research but the mechanism of its binding to polynucleotides has been poorly understood. This paper presents a study of the mechanisms of TFT self-aggregation and binding to DNA. Relaxation kinetics of TFT solutions show that the cyanine undergoes dimerization followed by dimer isomerisation. The interaction of TFT with DNA has been investigated using static methods, such as spectrophotometric and spectrofluorometric titrations under different conditions (salt content, temperature), fluorescence quenching, viscometric experiments and the T-jump relaxation method. The combined use of these techniques enabled us to show that the TFT monomer undergoes intercalation between the DNA base pairs and external binding according to a branched mechanism. Moreover, it has also been observed that, under dye excess conditions, the TFT dimer binds to the DNA grooves. The molecular structures of intercalated TFT and the groove-bound TFT dimer are obtained by performing QM/MM MD simulations.

Thought Field Therapy (TFT) as a treatment for anxiety symptoms: a randomized controlled trial.

PubMed

Irgens, Audun; Dammen, Toril; Nysæter, Tor Erik; Hoffart, Asle

2012-01-01

To investigate whether thought field therapy (TFT) has an impact on anxiety symptoms in patients with a variety of anxiety disorders. Forty-five patients were randomized to either TFT (n = 23) or a waiting list (n = 22) condition. The wait-list group was reassessed and compared with the TFT group two and a half months after the initial evaluation. After the reassessment, the wait-list patients received treatment with TFT. All 45 patients were followed up one to two weeks after TFT treatment, as well as at three and 12 months after treatment. Patients with an anxiety disorder, mostly outpatients. TFT aims to influence the body's bioenergy field by tapping on specific points along energy meridians, thereby relieving anxiety and other symptoms. Symptom Checklist 90-Revised, Hospital Anxiety and Depression Scale, the Sheehan Disability Scale. Repeated-measures analysis of variance was used to compare the TFT and the wait-list group. The TFT group had a significantly better outcome on two measures of anxiety and one measure of function. Follow-up data for all patients taken together showed a significant decrease in all symptoms during the one to two weeks between the pretreatment and the post-treatment assessments. The significant improvement seen after treatment was maintained at the three- and 12-month assessments. The results suggest that TFT may have an enduring anxiety-reducing effect. Copyright © 2012 Elsevier Inc. All rights reserved.

Ambient effect on thermal stability of amorphous InGaZnO thin film transistors

NASA Astrophysics Data System (ADS)

Xu, Jianeng; Wu, Qi; Xu, Ling; Xie, Haiting; Liu, Guochao; Zhang, Lei; Dong, Chengyuan

2016-12-01

The thermal stability of amorphous InGaZnO thin film transistors (a-IGZO TFTs) with various ambient gases was investigated. The a-IGZO TFTs in air were more thermally stable than the devices in the ambient argon. Oxygen, rather than nitrogen and moisture, was responsible for this improvement. Furthermore, the thermal stability of the a-IGZO TFTs improved with the increasing oxygen content in the surrounding atmosphere. The related physical mechanism was examined, indicating that the higher ambient oxygen content induced more combinations of the oxygen vacancies and adsorbed oxygen ions in the a-IGZO, which resulted in the larger defect formation energy. This larger defect formation energy led to the smaller variation in the threshold voltage for the corresponding TFT devices.

Micro-optics for simultaneous multi-spectral imaging applied to chemical/biological and IED detection

NASA Astrophysics Data System (ADS)

Hinnrichs, Michele

2012-06-01

Using diffractive micro-lenses configured in an array and placed in close proximity to the focal plane array will enable a small compact simultaneous multispectral imaging camera. This approach can be applied to spectral regions from the ultraviolet (UV) to the long-wave infrared (LWIR). The number of simultaneously imaged spectral bands is determined by the number of individually configured diffractive optical micro-lenses (lenslet) in the array. Each lenslet images at a different wavelength determined by the blaze and set at the time of manufacturing based on application. In addition, modulation of the focal length of the lenslet array with piezoelectric or electro-static actuation will enable spectral band fill-in allowing hyperspectral imaging. Using the lenslet array with dual-band detectors will increase the number of simultaneous spectral images by a factor of two when utilizing multiple diffraction orders. Configurations and concept designs will be presented for detection application for biological/chemical agents, buried IED's and reconnaissance. The simultaneous detection of multiple spectral images in a single frame of data enhances the image processing capability by eliminating temporal differences between colors and enabling a handheld instrument that is insensitive to motion.

The Tomato 14-3-3 Protein TFT4 Modulates H+ Efflux, Basipetal Auxin Transport, and the PKS5-J3 Pathway in the Root Growth Response to Alkaline Stress1[C][W

PubMed Central

Xu, Weifeng; Jia, Liguo; Shi, Weiming; Baluška, František; Kronzucker, Herbert J.; Liang, Jiansheng; Zhang, Jianhua

2013-01-01

Alkaline stress is a common environmental stress, in particular in salinized soils. Plant roots respond to a variety of soil stresses by regulating their growth, but the nature of the regulatory pathways engaged in the alkaline stress response (ASR) is not yet understood. Previous studies show that PIN-FORMED2, an auxin (indole-3-acetic acid [IAA]) efflux transporter, PKS5, a protein kinase, and DNAJ HOMOLOG3 (J3), a chaperone, play key roles in root H+ secretion by regulating plasma membrane (PM) H+-ATPases directly or by targeting 14-3-3 proteins. Here, we investigated the expression of all 14-3-3 gene family members (TOMATO 14-3-3 PROTEIN1 [TFT1]–TFT12) in tomato (Solanum lycopersicum) under ASR, showing the involvement of four of them, TFT1, TFT4, TFT6, and TFT7. When these genes were separately introduced into Arabidopsis (Arabidopsis thaliana) and overexpressed, only the growth of TFT4 overexpressors was significantly enhanced when compared with the wild type under stress. H+ efflux and the activity of PM H+-ATPase were significantly enhanced in the root tips of TFT4 overexpressors. Microarray analysis and pharmacological examination of the overexpressor and mutant plants revealed that overexpression of TFT4 maintains primary root elongation by modulating PM H+-ATPase-mediated H+ efflux and basipetal IAA transport in root tips under alkaline stress. TFT4 further plays important roles in the PKS5-J3 signaling pathway. Our study demonstrates that TFT4 acts as a regulator in the integration of H+ efflux, basipetal IAA transport, and the PKS5-J3 pathway in the ASR of roots and coordinates root apex responses to alkaline stress for the maintenance of primary root elongation. PMID:24134886

Enhancement of the Device Performance and the Stability with a Homojunction-structured Tungsten Indium Zinc Oxide Thin Film Transistor.

PubMed

Park, Hyun-Woo; Song, Aeran; Choi, Dukhyun; Kim, Hyung-Jun; Kwon, Jang-Yeon; Chung, Kwun-Bum

2017-09-14

Tungsten-indium-zinc-oxide thin-film transistors (WIZO-TFTs) were fabricated using a radio frequency (RF) co-sputtering system with two types of source/drain (S/D)-electrode material of conducting WIZO (homojunction structure) and the indium-tin oxide (ITO) (heterojunction structure) on the same WIZO active-channel layer. The electrical properties of the WIZO layers used in the S/D electrode and the active-channel layer were adjusted through oxygen partial pressure during the deposition process. To explain enhancements of the device performance and stability of the homojunction-structured WIZO-TFT, a systematic investigation of correlation between device performance and physical properties at the interface between the active layer and the S/D electrodes such as the contact resistance, surface/interfacial roughness, interfacial-trap density, and interfacial energy-level alignments was conducted. The homojunction-structured WIZO-TFT exhibited a lower contact resistance, smaller interfacial-trap density, and flatter interfacial roughness than the WIZO-TFT with the heterojunction structure. The 0.09 eV electron barrier of the homojunction-structured WIZO-TFT is lower than the 0.21 eV value that was obtained for the heterojunction-structured WIZO-TFT. This reduced electron barrier may be attributed to enhancements of device performance and stability, that are related to the carrier transport.

The effect of a source-contacted light shield on the electrical characteristics of an LTPS TFT

NASA Astrophysics Data System (ADS)

Kim, Miryeon; Sun, Wookyung; Kang, Jongseuk; Shin, Hyungsoon

2017-08-01

The electrical characteristics of a low-temperature polycrystalline silicon thin-film transistor (TFT) with a source-contacted light shield (SCLS) are observed and analyzed. Compared with that of a conventional TFT without a light shield (LS), the on-current of the TFT with an SCLS is lower because the SCLS blocks the fringing electric field from the drain to the active layer. Furthermore, the gate-to-source capacitance (C gs) of the TFT with an SCLS in the off and saturation regions is higher than that of a conventional TFT, which is due to the gate-to-LS capacitance (C g-LS). The electrical characteristics of the TFT with an SCLS are thoroughly investigated by two-dimensional device simulations, and a semi-empirical C g-LS model for SPICE simulation is proposed and verified.

The Electrochemical Behavior of Mo-Ta Alloy in Phosphoric Acid Solution for TFT-LCD Application.

PubMed

Lee, Sang-Hyuk; Kim, Byoung O; Seo, Jong Hyun

2015-10-01

Molybdenum-tantalum alloy thin film is a suitable material for the higher corrosion resistance and low resistivity for gate and data metal lines. In this study, Mo-Ta alloy thin films were prepared by using a DC magnetron co-sputtering system on a glass substrate. An abrupt increase in the etching rates of low Mo-Ta alloys was observed. From the observed impedance analysis, the defect densities in the MoTa oxide films increased from 5.4 x 10(21) (cm(-3)) to 8.02 x 10(21) (cm(-3)) up to the 6 at% of tantalum level; and above the 6 at% of tantalum level, the defect densities decreased. This electrochemical behavior is explained by the mechanical instability of the MoTa oxide film.

Rapid fabrication of a micro-ball lens array by extrusion for optical fiber applications.

PubMed

Shen, S C; Huang, J C

2009-07-20

Batch-fabrication of a micro-ball lens array (MBA) could not only reduce micro assembly costs but also replace conventional ball lenses or costly GRINs (Gradient Refractive Index) without compromising performance. Compared with conventional half-spherical micro-lenses, the MBA is a spherical micro-lens that can focus light in all directions, thus providing the flexibility required for optical applications. Current MBAs are made of SU-8 photoresist by an extrusion process rather than the traditional thermal reflow process. The aim of this study was to develop a new process for MBA batch-fabrication, performed at ambient temperature, by spin-coating SU-8 onto a silicon-wafer surface, which serves as an extrusion plate, and extruding it through a nozzle to form an MBA. The nozzle consists of a nozzle orifice and nozzle cavity, the former being defined and made from SU-8 photoresist using ultra-violet (UV) lithography, which results in good mechanical properties. In this paper, the fabrication of 4 x 4 MBAs with diameters ranging from 60 to 550 um is described. Optical measurements indicated a diameter variance within 3% and a maximum coupling efficiency of approximately 62% when the single mode fiber (SMF) was placed at a distance of 10 um from the MBA. The results of this study proved that MBA fabrication by the extrusion process can enhance the coupling efficiency.

Electrical properties of solution processed highly transparent ZnO TFT with organic gate dielectric

NASA Astrophysics Data System (ADS)

Pandya, Nirav C.; Joshi, Nikhil G.; Trivedi, U. N.; Joshi, U. S.

2013-02-01

All oxide thin film transistors (TFT) with zinc oxide active layer were fabricated by chemical solution deposition (CSD) using aqueous solutions on glass substrate. Thin film transistors (TFTs) with amorphous zinc oxide as channel layers and poly-vinyl alcohol as dielectric layers were fabricated at low temperatures by chemical solution deposition (CSD). Atomic force microscopy (AFM) confirmed nano grain size with fairly smooth surface topography. Very small leakage currents were achieved in the transfer curves, while soft saturation was observed in the output current voltage (I-V) characteristics of the device. Optical transmission of better than 87% in the visible region was estimated, which is better than the organic gate insulator based ZnO TFTs reported so far. Our results offer lot of promise to TFT based display and optoelectronics.

Plasma-Sprayed Titanium Patterns for Enhancing Early Cell Responses

NASA Astrophysics Data System (ADS)

Shi, Yunqi; Xie, Youtao; Pan, Houhua; Zheng, Xuebin; Huang, Liping; Ji, Fang; Li, Kai

2016-06-01

Titanium coating has been widely used as a biocompatible metal in biomedical applications. However, the early cell responses and long-term fixation of titanium implants are not satisfied. To obviate these defects, in this paper, micro-post arrays with various widths (150-1000 μm) and intervals (100-300 μm) were fabricated on the titanium substrate by template-assisted plasma spraying technology. In vitro cell culture experiments showed that MC3T3-E1 cells exhibited significantly higher osteogenic differentiation as well as slightly improved adhesion and proliferation on the micro-patterned coatings compared with the traditional one. The cell number on the pattern with 1000 µm width reached 130% after 6 days of incubation, and the expressions of osteopontin (OPN) as well as osteocalcin (OC) were doubled. No obvious difference was found in cell adhesion on various size patterns. The present micro-patterned coatings proposed a new modification method for the traditional plasma spraying technology to enhance the early cell responses and convenience for the bone in-growth.

Microfabricated instruments and methods to treat recurrent corneal erosions

DOEpatents

Britton, Jr., Charles L.; D'urso, Brian R.; Chaum, Edward; Simpson, John T.; Baba, Justin S.; Ericson, M. Nance; Warmack, Robert J.

2015-06-02

In one embodiment, the present invention provides a device and method for treating recurrent corneal erosion. In one embodiment, the method includes the steps of contacting an epithelium layer of a cornea with an array of glass micro-rods including a plurality of sharp features having a length that penetrates a Bowman's layer of the eye, wherein the plurality of sharp features of the array of glass micro-rods produces a plurality of punctures in the Bowman's layer of the eye that are of micro-scale or less. In another embodiment, the present invention provides a method and device for drug delivery. In one embodiment, the device includes an array of glass micro-rods, wherein at least one glass micro-rod of the array of glass micro-rods includes a sharp feature opposite a base of the array of glass micro-rods, wherein the sharp feature includes a treated surface for delivering a chemical compound to the eye.

Microfabricated instruments and methods to treat recurrent corneal erosion

DOEpatents

Britton, Charles L; D& #x27; Urso, Brian R; Chaum, Edward; Simpson, John T; Baba, Justin S; Ericson, M. Nance; Warmack, Robert J

2013-11-26

In one embodiment, the present invention provides a device and method for treating recurrent corneal erosion. In one embodiment, the method includes the steps of contacting an epithelium layer of a cornea with an array of glass micro-rods including a plurality of sharp features having a length that penetrates a Bowman's layer of the eye, wherein the plurality of sharp features of the array of glass micro-rods produces a plurality of punctures in the Bowman's layer of the eye that are of micro-scale or less. In another embodiment, the present invention provides a method and device for drug delivery. In one embodiment, the device includes an array of glass micro-rods, wherein at least one glass micro-rod of the array of glass micro-rods includes a sharp feature opposite a base of the array of glass micro-rods, wherein the sharp feature includes a treated surface for delivering a chemical compound to the eye.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Jun, E-mail: lijun_yt@163.com; Key Laboratory of Advanced Display and System Applications, Ministry of Education, Shanghai University, Shanghai 200072; Huang, Chuan-Xin

Graphical abstract: This work reports the Ba content on thin film transistor based on a novel BaZnSnO semiconductor using solution process. - Highlights: • No reports about BaZnSnO thin film using solution process. • BaZnSnO thin film transistor (TFT) was firstly fabricated. • BaZnSnO-TFT shows a acceptable performace. • Influence of Ba content on BaZnSnO-TFT. - Abstract: A novel BaZnSnO semiconductor is fabricated using solution process and the influence of Ba addition on the structure, the chemical state of oxygen and electrical performance of BaZnSnO thin films are investigated. A high performance BaZnSnO-based thin film transistor with 15 mol% Bamore » is obtained, showing a saturation mobility of 1.94 cm{sup 2}/V s, a threshold voltage of 3.6 V, an on/off current ratio of 6.2 × 10{sup 6}, a subthreshold swing of 0.94 V/decade, and a good bias stability. Transistors with solution processed BaZnSnO films are promising candidates for the development of future large-area, low-cost and high-performance electronic devices.« less

FPGA Control System for the Automated Test of MicroShutters

NASA Technical Reports Server (NTRS)

Lyness, Eric; Rapchun, David A.; Moseley, S. Harvey

2008-01-01

The James Webb Space Telescope, scheduled to replace the Hubble in 2013, must simultaneously observe hundreds of faint galaxies. This requirement has led to the development of a programmable transmission mask which can be adapted to admit light from an arbitrary pattern of galaxies into its spectrograph. This programmable mask will contain a large array of micro-electromechanical (MEMs) devices called MicroShutters. These microscopic shutters physically open and close like the shutter on a camera, except each shutter is microscopic in size and an array 365 by 171 is used to select the objects under spectroscopic observation at a given time, and to block the unwanted background light from other areas. NASA developed and is currently refining the exceptionally difficult process of manufacturing these shutters. This paper describes how the authors used LabVIEW FPGA and a reconfigurable I/O board to control the shutters in a test chamber and how the flexibility of the system allows us to continue to modify the control algorithms as NASA optimizes the performance of the MicroShutter arrays.

The superiority of the two-thumb over the two-finger technique for single-rescuer infant cardiopulmonary resuscitation.

PubMed

Lee, Sang Yoon; Hong, Jun Young; Oh, Je Hyeok; Son, Sun-Han

2017-03-21

The two-finger technique (TFT) using the index-middle fingers of the right hand (TFT-R23) was recently confirmed to produce deeper chest compression depth (CCD) compared with the TFT using any other fingers. This study was carried out to confirm whether the TFT-R23 would be as effective as the two-thumb technique (TTT). In addition, individual finger strengths were measured to identify the reasons why the TTT and TFT-R23 produced deeper CCD than any other methods. This prospective randomized cross-over trial compared TTT with TFT-R23. A total of 37 doctors conducted 2 min single-rescuer cardiopulmonary resuscitation using TTT and TFT-R23 in a random order using a 3-month-old sized infant manikin laid on the floor. The chest compression to ventilation ratio was set to 15 : 2. In addition, finger strengths were measured using a pinch meter. The actual CCD of the TTT was significantly deeper than that of the TFT-R23 (41.3±1.3 vs. 39.8±1.5 mm, P<0.001). Although the hands-off time of the TTT was significantly longer than that of the TFT-R23 (55.6±5.7 vs. 53.6±5.8 s, P=0.002), the mean difference was only 2.0±3.7 s (95% confidence interval: 0.755-3.245). The finger strength of the TTT was significantly higher than that of TFT-R23 (23.8±10.1 vs. 13.7±5.1 kg, P<0.001). The TTT produced deeper CCD compared with that of the TFT-R23 because the finger strength of the TTT was significantly higher than that of the TFT-R23.

The effect of annealing ambient on the characteristics of an indium-gallium-zinc oxide thin film transistor.

PubMed

Park, Soyeon; Bang, Seokhwan; Lee, Seungjun; Park, Joohyun; Ko, Youngbin; Jeon, Hyeongtag

2011-07-01

In this study, the effects of different annealing conditions (air, O2, N2, vacuum) on the chemical and electrical characteristics of amorphous indium-gallium-zinc oxide (a-IGZO) thin film transistors (TFT) were investigated. The contact resistance and interface properties between the IGZO film and the gate dielectric improved after an annealing treatment. However, the chemical bonds in the IGZO bulk changed under various annealing atmospheres, which, in turn, altered the characteristics of the TFTs. The TFTs annealed in vacuum and N2 ambients exhibited undesired switching properties due to the high carrier concentration (>10(17) cm(-3)) of the IGZO active layer. In contrast, the IGZO TFTs annealed in air and oxygen ambients displayed clear transfer characteristics due to an adequately adjusted carrier concentration in the operating range of the TFT. Such an optimal carrier concentration arose through the stabilization of unstable chemical bonds in the IGZO film. With regard to device performance, the TFTs annealed in O2 and air exhibited saturation mobility values of 8.29 and 7.54 cm2/Vs, on-off ratios of 7.34 x 10(8) and 3.95 x 10(8), and subthreshold swing (SS) values of 0.23 and 0.19 V/decade, respectively. Therefore, proper annealing ambients contributed to internal modifications in the IGZO structure and led to an enhancement in the oxidation state of the metal. As a result, defects such as oxygen vacancies were eliminated. Oxygen annealing is thus effective for controlling the carrier concentration of the active layer, decreasing electron traps, and enhancing TFT performance.

Methods for fabricating a micro heat barrier

DOEpatents

Marshall, Albert C.; Kravitz, Stanley H.; Tigges, Chris P.; Vawter, Gregory A.

2004-01-06

Methods for fabricating a highly effective, micron-scale micro heat barrier structure and process for manufacturing a micro heat barrier based on semiconductor and/or MEMS fabrication techniques. The micro heat barrier has an array of non-metallic, freestanding microsupports with a height less than 100 microns, attached to a substrate. An infrared reflective membrane (e.g., 1 micron gold) can be supported by the array of microsupports to provide radiation shielding. The micro heat barrier can be evacuated to eliminate gas phase heat conduction and convection. Semi-isotropic, reactive ion plasma etching can be used to create a microspike having a cusp-like shape with a sharp, pointed tip (<0.1 micron), to minimize the tip's contact area. A heat source can be placed directly on the microspikes. The micro heat barrier can have an apparent thermal conductivity in the range of 10.sup.-6 to 10.sup.-7 W/m-K. Multiple layers of reflective membranes can be used to increase thermal resistance.

Micro-computed Tomography versus the Cross-sectioning Method to Evaluate Dentin Defects Induced by Different Mechanized Instrumentation Techniques.

PubMed

Stringheta, Carolina Pessoa; Pelegrine, Rina Andréa; Kato, Augusto Shoji; Freire, Laila Gonzales; Iglecias, Elaine Faga; Gavini, Giulio; Bueno, Carlos Eduardo da Silveira

2017-12-01

The objective of this study was to compare the methods of micro-computed tomography (micro-CT) and cross-sectioning followed by stereomicroscopy in assessing dentinal defects after instrumentation with different mechanized systems. Forty mesial roots of mandibular molars were scanned and divided into 4 groups (n = 10): Group R, Reciproc; Group PTN, ProTaper Next; Group WOG, WaveOne Gold; Group PDL, ProDesign Logic. After instrumentation, the roots were once again submitted to a micro-CT scan, and then sectioned at 3, 6, and 9 mm from the apex, and assessed for the presence of complete and incomplete dentinal defects under a stereomicroscope. The nonparametric Kruskal-Wallis, Friedman, and Wilcoxon tests were used in the statistical analysis. The study used a significance level of 5%. The total number of defects observed by cross-sectioning followed by stereomicroscopy was significantly higher than that observed by micro-CT, in all of the experimental groups (P ≤ .05). All of the defects identified in the postoperative period were already present in the corresponding preoperative period. There was no significant difference among the instrumentation systems as to the median numbers of defects, for either cross-sectioning followed by stereomicroscopy or micro-CT, at all the root levels (P > .05). In the micro-CT analysis, no significant difference was found between the median numbers of pre- and postinstrumentation defects, regardless of the instrumentation system (P > .05). None of the evaluated instrumentation systems led to the formation of new dentin defects. All of the defects identified in the stereomicroscopic analysis were already present before instrumentation, or were absent at both time points in the micro-CT analysis, indicating that the formation of new defects resulted from the sectioning procedure performed before stereomicroscopy and not from instrumentation. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Use of thin film transistor liquid crystal display (TFT-LCD) waste glass in the production of ceramic tiles.

PubMed

Lin, Kae-Long

2007-09-05

In this study, we employ the following operating conditions: varied pressure (25 kgf/cm(2)), sintering temperature (900-1200 degrees C), sintering time (6h), percentage of thin film transistor liquid crystal display (TFT-LCD) waste glass by weight (0-50%) and temperature rising at a rate of 5 degrees C/min, to fabricate clay tiles. The sintering characteristics of the clay blended with TFT-LCD waste glass tiles are examined to evaluate the feasibility of the reuse of TFT-LCD waste glass. TFT-LCD waste glass contains large amounts of glass. The TCLP leaching concentrations all met the ROC EPAs current regulatory thresholds. The addition of TFT-LCD waste glass to the mixture, increased the apparent weight loss. The incorporation of 50% TFT-LCD waste glass resulted in a significant increase in the porosity ratio of the specimens compared to the porosity ratio of the ceramic tile containing TFT-LCD waste glass. The main constituent in both the clay tile and the clay with TFT-LCD waste glass samples is quartz. Increasing the temperature resulted in an increase in the flexural strength and resistance to abrasion in the tiles. The porosity ratio decreases as shrinkage increases. The relation between the porosity ratio and the hardness of the tiles used in the study is also shown.

PINPIN a-Si:H based structures for X-ray image detection using the laser scanning technique

NASA Astrophysics Data System (ADS)

Fernandes, M.; Vygranenko, Y.; Vieira, M.

2015-05-01

Conventional film based X-ray imaging systems are being replaced by their digital equivalents. Different approaches are being followed by considering direct or indirect conversion, with the later technique dominating. The typical, indirect conversion, X-ray panel detector uses a phosphor for X-ray conversion coupled to a large area array of amorphous silicon based optical sensors and a couple of switching thin film transistors (TFT). The pixel information can then be readout by switching the correspondent line and column transistors, routing the signal to an external amplifier. In this work we follow an alternative approach, where the electrical switching performed by the TFT is replaced by optical scanning using a low power laser beam and a sensing/switching PINPIN structure, thus resulting in a simpler device. The optically active device is a PINPIN array, sharing both front and back electrical contacts, deposited over a glass substrate. During X-ray exposure, each sensing side photodiode collects photons generated by the scintillator screen (560 nm), charging its internal capacitance. Subsequently a laser beam (445 nm) scans the switching diodes (back side) retrieving the stored charge in a sequential way, reconstructing the image. In this paper we present recent work on the optoelectronic characterization of the PINPIN structure to be incorporated in the X-ray image sensor. The results from the optoelectronic characterization of the device and the dependence on scanning beam parameters are presented and discussed. Preliminary results of line scans are also presented.

Low dose digital X-ray imaging with avalanche amorphous selenium

NASA Astrophysics Data System (ADS)

Scheuermann, James R.; Goldan, Amir H.; Tousignant, Olivier; Léveillé, Sébastien; Zhao, Wei

2015-03-01

Active Matrix Flat Panel Imagers (AMFPI) based on an array of thin film transistors (TFT) have become the dominant technology for digital x-ray imaging. In low dose applications, the performance of both direct and indirect conversion detectors are limited by the electronic noise associated with the TFT array. New concepts of direct and indirect detectors have been proposed using avalanche amorphous selenium (a-Se), referred to as high gain avalanche rushing photoconductor (HARP). The indirect detector utilizes a planar layer of HARP to detect light from an x-ray scintillator and amplify the photogenerated charge. The direct detector utilizes separate interaction (non-avalanche) and amplification (avalanche) regions within the a-Se to achieve depth-independent signal gain. Both detectors require the development of large area, solid state HARP. We have previously reported the first avalanche gain in a-Se with deposition techniques scalable to large area detectors. The goal of the present work is to demonstrate the feasibility of large area HARP fabrication in an a-Se deposition facility established for commercial large area AMFPI. We also examine the effect of alternative pixel electrode materials on avalanche gain. The results show that avalanche gain > 50 is achievable in the HARP layers developed in large area coaters, which is sufficient to achieve x-ray quantum noise limited performance down to a single x-ray photon per pixel. Both chromium (Cr) and indium tin oxide (ITO) have been successfully tested as pixel electrodes.

Note: A resonating reflector-based optical system for motion measurement in micro-cantilever arrays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sathishkumar, P.; Punyabrahma, P.; Sri Muthu Mrinalini, R.

A robust, compact optical measurement unit for motion measurement in micro-cantilever arrays enables development of portable micro-cantilever sensors. This paper reports on an optical beam deflection-based system to measure the deflection of micro-cantilevers in an array that employs a single laser source, a single detector, and a resonating reflector to scan the measurement laser across the array. A strategy is also proposed to extract the deflection of individual cantilevers from the acquired data. The proposed system and measurement strategy are experimentally evaluated and demonstrated to measure motion of multiple cantilevers in an array.

Fabrication of a Micro-Needle Array Electrode by Thermal Drawing for Bio-Signals Monitoring

PubMed Central

Ren, Lei; Jiang, Qing; Chen, Keyun; Chen, Zhipeng; Pan, Chengfeng; Jiang, Lelun

2016-01-01

A novel micro-needle array electrode (MAE) fabricated by thermal drawing and coated with Ti/Au film was proposed for bio-signals monitoring. A simple and effective setup was employed to form glassy-state poly (lactic-co-glycolic acid) (PLGA) into a micro-needle array (MA) by the thermal drawing method. The MA was composed of 6 × 6 micro-needles with an average height of about 500 μm. Electrode-skin interface impedance (EII) was recorded as the insertion force was applied on the MAE. The insertion process of the MAE was also simulated by the finite element method. Results showed that MAE could insert into skin with a relatively low compression force and maintain stable contact impedance between the MAE and skin. Bio-signals, including electromyography (EMG), electrocardiography (ECG), and electroencephalograph (EEG) were also collected. Test results showed that the MAE could record EMG, ECG, and EEG signals with good fidelity in shape and amplitude in comparison with the commercial Ag/AgCl electrodes, which proves that MAE is an alternative electrode for bio-signals monitoring. PMID:27322278

Fabrication of a Micro-Needle Array Electrode by Thermal Drawing for Bio-Signals Monitoring.

PubMed

Ren, Lei; Jiang, Qing; Chen, Keyun; Chen, Zhipeng; Pan, Chengfeng; Jiang, Lelun

2016-06-17

A novel micro-needle array electrode (MAE) fabricated by thermal drawing and coated with Ti/Au film was proposed for bio-signals monitoring. A simple and effective setup was employed to form glassy-state poly (lactic-co-glycolic acid) (PLGA) into a micro-needle array (MA) by the thermal drawing method. The MA was composed of 6 × 6 micro-needles with an average height of about 500 μm. Electrode-skin interface impedance (EII) was recorded as the insertion force was applied on the MAE. The insertion process of the MAE was also simulated by the finite element method. Results showed that MAE could insert into skin with a relatively low compression force and maintain stable contact impedance between the MAE and skin. Bio-signals, including electromyography (EMG), electrocardiography (ECG), and electroencephalograph (EEG) were also collected. Test results showed that the MAE could record EMG, ECG, and EEG signals with good fidelity in shape and amplitude in comparison with the commercial Ag/AgCl electrodes, which proves that MAE is an alternative electrode for bio-signals monitoring.

Patterning nanowire and micro-nanoparticle array on micropillar-structured surface: Experiment and modeling.

PubMed

Lin, Chung Hsun; Guan, Jingjiao; Chau, Shiu Wu; Chen, Shia Chung; Lee, L James

2010-08-04

DNA molecules in a solution can be immobilized and stretched into a highly ordered array on a solid surface containing micropillars by molecular combing technique. However, the mechanism of this process is not well understood. In this study, we demonstrated the generation of DNA nanostrand array with linear, zigzag, and fork-zigzag patterns and the microfluidic processes are modeled based on a deforming body-fitted grid approach. The simulation results provide insights for explaining the stretching, immobilizing, and patterning of DNA molecules observed in the experiments.

Detection of human microRNAs across miRNA Array and Next Generation DNA Sequencing Platforms

EPA Science Inventory

microRNA (miRNAs) are non-coding RNA molecules between 19 and 30 nucleotides in length that are believed to regulate approximately 30 per cent of all human genes. They act as negative regulators of their gene targets in many biological processes. Recent developments in microar...

In vivo and in vitro studies of borate based glass micro-fibers for dermal repairing.

PubMed

Zhou, Jie; Wang, Hui; Zhao, Shichang; Zhou, Nai; Li, Le; Huang, Wenhai; Wang, Deping; Zhang, Changqing

2016-03-01

Full-thickness skin defects represent urgent clinical problem nowadays. Wound dressing materials are hotly needed to induce dermal reconstruction or to treat serious skin defects. In this study, the borate bioactive glass (BG) micro-fibers were fabricated and compared with the traditional material 45S5 Bioglass(®) (SiG) micro-fibers. The morphology, biodegradation and bioactivity of BG and SiG micro-fibers were investigated in vitro. The wound size reduction and angiogenic effects of BG and SiG micro-fibers were evaluated by the rat full-thickness skin defect model and Microfil technique in vivo. Results indicated that the BG micro-fibers showed thinner fiber diameter (1 μm) and better bioactivity than the SiG micro-fibers did. The ionic extracts of BG and SiG micro-fibers were not toxic to human umbilical vein endothelial cells (HUVECs). In vivo, the BG micro-fiber wound dressings obviously enhanced the formation of blood vessel, and resulted in a much faster wound size reduction than the SiG micro-fibers, or than the control groups, after 9 days application. The good skin defect reconstruction ability of BG micro-fibers contributed to the B element in the composition, which results in the better bioactivity and angiogenesis. As shown above, the novel bioactive borate glass micro-fibers are expected to provide a promising therapeutic alternative for dermal reconstruction or skin defect repair. Copyright © 2015 Elsevier B.V. All rights reserved.

Role of deposition and annealing of the top gate dielectric in a-IGZO TFT-based dual-gate ion-sensitive field-effect transistors

NASA Astrophysics Data System (ADS)

Kumar, Narendra; Sutradhar, Moitri; Kumar, Jitendra; Panda, Siddhartha

2017-03-01

The deposition of the top gate dielectric in thin film transistor (TFT)-based dual-gate ion-sensitive field-effect transistors (DG ISFETs) is critical, and expected not to affect the bottom gate TFT characteristics, while providing a higher pH sensitive surface and efficient capacitive coupling between the gates. Amorphous Ta2O5, in addition to having good sensing properties, possesses a high dielectric constant of ˜25 making it well suited as the top gate dielectric in a DG ISFET by providing higher capacitive coupling (ratio of C top/C bottom) leading to higher amplification. To avoid damage of the a-IGZO channel reported to be caused by plasma exposure, deposition of Ta2O5 by e-beam evaporation followed by annealing was investigated in this work to obtain sensitivity over the Nernst limit. The deteriorated bottom gate TFT characteristics, indicated by an increase in the channel conductance, confirmed that plasma exposure is not the sole contributor to the changes. Oxygen vacancies at the Ta2O5/a-IGZO interface, which emerged during processing, increased the channel conductivity, became filled by optimum annealing in oxygen at 400 °C for 1 h, which was confirmed by an x-ray photoelectron spectroscopy depth profiling analysis. The obtained pH sensitivity of the TFT-based DG ISFET was 402 mV pH-1, which is about 6.8 times the Nernst limit (59 mV pH-1). The concept of capacitive coupling was also demonstrated by simulating an a-IGZO-based DG TFT structure. Here, the exposure of the top gate dielectric to the electrolyte without applying any top gate bias led to changes in the measured threshold voltage of the bottom gate TFT, and this obviated the requirement of a reference electrode needed in conventional ISFETs and other reported DG ISFETs. These devices, with high sensitivities and requiring low volumes (˜2 μl) of analyte solution, could be potential candidates for utilization as chemical sensors and biosensors.

Time delay and integration array (TDI) using charge transfer device technology. Phase 2, volume 1: Technical

NASA Technical Reports Server (NTRS)

1977-01-01

The 20x9 TDI array was developed to meet the LANDSAT Thematic Mapper Requirements. This array is based upon a self-aligned, transparent gate, buried channel process. The process features: (1) buried channel, four phase, overlapping gate CCD's for high transfer efficiency without fat zero; (2) self-aligned transistors to minimize clock feedthrough and parasitic capacitance; and (3) transparent tin oxide electrode for high quantum efficiency with front surface irradiation. The requirements placed on the array and the performance achieved are summarized. This data is the result of flat field measurements only, no imaging or dynamic target measurements were made during this program. Measurements were performed with two different test stands. The bench test equipment fabricated for this program operated at the 8 micro sec line time and employed simple sampling of the gated MOSFET output video signal. The second stand employed Correlated Doubled Sampling (CDS) and operated at 79.2 micro sec line time.

Stability of amorphous silicon thin film transistors and circuits

NASA Astrophysics Data System (ADS)

Liu, Ting

Hydrogenated amorphous silicon thin-film transistors (a-Si:H TFTs) have been widely used for the active-matrix addressing of flat panel displays, optical scanners and sensors. Extending the application of the a-Si TFTs from switches to current sources, which requires continuous operation such as for active-matrix organic light-emitting-diode (AMOLED) pixels, makes stability a critical issue. This thesis first presents a two-stage model for the stability characterization and reliable lifetime prediction for highly stable a-Si TFTs under low gate-field stress. Two stages of the threshold voltage shift are identified from the decrease of the drain saturation current under low-gate field. The first initial stage dominates up to hours or days near room temperature. It can be characterized with a stretched-exponential model, with the underlying physical mechanism of charge trapping in the gate dielectric. The second stage dominates in the long term and then saturates. It corresponds to the breaking of weak bonds in the amorphous silicon. It can be modeled with a "unified stretched exponential fit," in which a thermalization energy is used to unify experimental measurements of drain current decay at different temperatures into a single curve. Two groups of experiments were conducted to reduce the drain current instability of a-Si TFTs under prolonged gate bias. Deposition conditions for the silicon nitride (SiNx) gate insulator and the a-Si channel layer were varied, and TFTs were fabricated with all reactive ion etching steps, or with all wet etching steps, the latter in a new process. The two-stage model that unites charge trapping in the SiNx gate dielectric and defect generation in the a-Si channel was used to interpret the experimental results. We identified the optimal substrate temperature, gas flow ratios, and RF deposition power densities. The stability of the a-Si channel depends also on the deposition conditions for the underlying SiNx gate insulator. TFTs made with wet etching are more stable than TFTs made with reactive ion etching. Combining the various improvements raised the extrapolated 50% decay time of the drain current of back channel passivated dry-etched TFTs under continuous operation at 20°C from 3.3 x 104 sec (9.2 hours) to 4.4 x 107 sec (1.4 years). The 50% lifetime can be further improved by ˜2 times through wet etching process. Two assumptions in the two-stage model were revisited. First, the distribution of the gap state density in a-Si was obtained with the field-effect technique. The redistribution of the gap state density after low-gate field stress supports the idea that defect creation in a-Si dominates in the long term. Second, the drain-bias dependence of drain current degradation was measured and modeled. The unified stretched exponential was validated for a-Si TFTs operating in saturation. Finally, a new 3-TFT voltage-programmed pixel circuit with an in-pixel current source is presented. This circuit is largely insensitive to the TFT threshold voltage shift. The fabricated pixel circuit provides organic light-emitting diode (OLED) currents ranging from 25 nA to 2.9 microA, an on/off ratio of 116 at typical quarter graphics display resolution (QVGA) display timing. The overall conclusion of this thesis research is that the operating life of a-Si TFTs can be quite long, and that these transistors can expect to find yet more applications in large area electronics.

A mixed solution-processed gate dielectric for zinc-tin oxide thin-film transistor and its MIS capacitance

NASA Astrophysics Data System (ADS)

Kim, Hunho; Kwack, Young-Jin; Yun, Eui-Jung; Choi, Woon-Seop

2016-09-01

Solution-processed gate dielectrics were fabricated with the combined ZrO2 and Al2O3 (ZAO) in the form of mixed and stacked types for oxide thin film transistors (TFTs). ZAO thin films prepared with double coatings for solid gate dielectrics were characterized by analytical tools. For the first time, the capacitance of the oxide semiconductor was extracted from the capacitance-voltage properties of the zinc-tin oxide (ZTO) TFTs with the combined ZAO dielectrics by using the proposed metal-insulator-semiconductor (MIS) structure model. The capacitance evolution of the semiconductor from the TFT model structure described well the threshold voltage shift observed in the ZTO TFT with the ZAO (1:2) gate dielectric. The electrical properties of the ZTO TFT with a ZAO (1:2) gate dielectric showed low voltage driving with a field effect mobility of 37.01 cm2/Vs, a threshold voltage of 2.00 V, an on-to-off current ratio of 1.46 × 105, and a subthreshold slope of 0.10 V/dec.

A mixed solution-processed gate dielectric for zinc-tin oxide thin-film transistor and its MIS capacitance

PubMed Central

Kim, Hunho; Kwack, Young-Jin; Yun, Eui-Jung; Choi, Woon-Seop

2016-01-01

Solution-processed gate dielectrics were fabricated with the combined ZrO2 and Al2O3 (ZAO) in the form of mixed and stacked types for oxide thin film transistors (TFTs). ZAO thin films prepared with double coatings for solid gate dielectrics were characterized by analytical tools. For the first time, the capacitance of the oxide semiconductor was extracted from the capacitance-voltage properties of the zinc-tin oxide (ZTO) TFTs with the combined ZAO dielectrics by using the proposed metal-insulator-semiconductor (MIS) structure model. The capacitance evolution of the semiconductor from the TFT model structure described well the threshold voltage shift observed in the ZTO TFT with the ZAO (1:2) gate dielectric. The electrical properties of the ZTO TFT with a ZAO (1:2) gate dielectric showed low voltage driving with a field effect mobility of 37.01 cm2/Vs, a threshold voltage of 2.00 V, an on-to-off current ratio of 1.46 × 105, and a subthreshold slope of 0.10 V/dec. PMID:27641430

Impact of active layer thickness of nitrogen-doped In–Sn–Zn–O films on materials and thin film transistor performances

NASA Astrophysics Data System (ADS)

Li, Zhi-Yue; Yang, Hao-Zhi; Chen, Sheng-Chi; Lu, Ying-Bo; Xin, Yan-Qing; Yang, Tian-Lin; Sun, Hui

2018-05-01

Nitrogen-doped indium tin zinc oxide (ITZO:N) thin film transistors (TFTs) were deposited on SiO2 (200 nm)/p-Si〈1 0 0〉 substrates by RF magnetron sputtering at room temperature. The structural, chemical compositions, surface morphology, optical and electrical properties as a function of the active layer thickness were investigated. As the active layer thickness increases, Zn content decreases and In content increases gradually. Meanwhile, Sn content is almost unchanged. When the thickness of the active layer is more than 45 nm, the ITZO:N films become crystallized and present a crystal orientation along InN(0 0 2) plan. No matter what the thickness is, ITZO:N films always display a high transmittance above 80% in the visible region. Their optical band gaps fluctuate between 3.4 eV and 3.62 eV. Due to the dominance of low interface trap density and high carrier concentration, ITZO:N TFT shows enhanced electrical properties as the active layer thickness is 35 nm. Its field-effect mobility, on/off radio and sub-threshold swing are 17.53 cm2 V‑1 · s‑1, 106 and 0.36 V/dec, respectively. These results indicate that the suitable thickness of the active layer can enhance the quality of ITZO:N films and decrease the defects density of ITZO:N TFT. Thus, the properties of ITZO:N TFT can be optimized by adjusting the thickness of the active layer.

Accelerated Evolution in the Death Galaxy

NASA Astrophysics Data System (ADS)

Austin, Robert; Tung, Chih-Kuan; Gong, Xiu-Quing; Lambert, Guillaume; Liao, David

2010-03-01

We recall 4 main guiding principles of evolution: 1) instability of defections, 2) stress induced non-random mutations, 3) genetic heterogeneity, and 4) fragmented populations. Our previous preliminary experiments have been relatively simple 1-D stress experiments. We are proceeding with 2-D experiments whose design is guided by these principles. Our new experiment we have dubbed the Death Galaxy because of it's use of these design principles. The ``galaxy'' name comes from the fact that the structure is designed as an interconnected array of micro-ecologies, these micro-ecologies are similar to the stars that comprise an astronomical galaxy, and provide the fragmented small populations. A gradient of the antibiotic Cipro is introduced across the galaxy, and we will present results which show how bacterial evolution resulting in resistance to Cipro is accelerated by the physics principles underlying the device.

A micro-machined source transducer for a parametric array in air.

PubMed

Lee, Haksue; Kang, Daesil; Moon, Wonkyu

2009-04-01

Parametric array applications in air, such as highly directional parametric loudspeaker systems, usually rely on large radiators to generate the high-intensity primary beams required for nonlinear interactions. However, a conventional transducer, as a primary wave projector, requires a great deal of electrical power because its electroacoustic efficiency is very low due to the large characteristic mechanical impedance in air. The feasibility of a micro-machined ultrasonic transducer as an efficient finite-amplitude wave projector was studied. A piezoelectric micro-machined ultrasonic transducer array consisting of lead zirconate titanate uni-morph elements was designed and fabricated for this purpose. Theoretical and experimental evaluations showed that a micro-machined ultrasonic transducer array can be used as an efficient source transducer for a parametric array in air. The beam patterns and propagation curves of the difference frequency wave and the primary wave generated by the micro-machined ultrasonic transducer array were measured. Although the theoretical results were based on ideal parametric array models, the theoretical data explained the experimental results reasonably well. These experiments demonstrated the potential of micro-machined primary wave projector.

Solid-state flat panel imager with avalanche amorphous selenium

NASA Astrophysics Data System (ADS)

Scheuermann, James R.; Howansky, Adrian; Goldan, Amir H.; Tousignant, Olivier; Levéille, Sébastien; Tanioka, K.; Zhao, Wei

2016-03-01

Active matrix flat panel imagers (AMFPI) have become the dominant detector technology for digital radiography and fluoroscopy. For low dose imaging, electronic noise from the amorphous silicon thin film transistor (TFT) array degrades imaging performance. We have fabricated the first prototype solid-state AMFPI using a uniform layer of avalanche amorphous selenium (a-Se) photoconductor to amplify the signal to eliminate the effect of electronic noise. We have previously developed a large area solid-state avalanche a-Se sensor structure referred to as High Gain Avalanche Rushing Photoconductor (HARP) capable of achieving gains of 75. In this work we successfully deposited this HARP structure onto a 24 x 30 cm2 TFT array with a pixel pitch of 85 μm. An electric field (ESe) up to 105 Vμm-1 was applied across the a-Se layer without breakdown. Using the HARP layer as a direct detector, an X-ray avalanche gain of 15 +/- 3 was achieved at ESe = 105 Vμm-1. In indirect mode with a 150 μm thick structured CsI scintillator, an optical gain of 76 +/- 5 was measured at ESe = 105 Vμm-1. Image quality at low dose increases with the avalanche gain until the electronic noise is overcome at a constant exposure level of 0.76 mR. We demonstrate the success of a solid-state HARP X-ray imager as well as the largest active area HARP sensor to date.

Investigation into Generation of Micro Features by Localised Electrochemical Deposition

NASA Astrophysics Data System (ADS)

Debnath, Subhrajit; Laskar, Hanimur Rahaman; Bhattacharyya, B.

2017-11-01

With the fast advancement of technology, localised electrochemical deposition (LECD) is becoming very advantageous in generating high aspect ratio micro features to meet the steep demand in modern precision industries of the present world. Except many other advantages, this technology is highly uncomplicated and economical for fabricating metal micro-parts with in micron ranges. In the present study, copper micro-columns have been fabricated utilizing LECD process. Different process parameters such as voltage, frequency, duty ratio and electrolyte concentration, which affect the deposition performance have been identified and their effects on deposition performances such as deposition rate, height and diameter of the micro-columns have been experimentally investigated. Taguchi's methodology has been used to study the effects as well as to obtain the optimum values of process parameters so that localised deposition with best performance can be achieved. Moreover, the generated micro-columns were carefully observed under optical and scanning electron microscope from where the surface quality of the deposited micro-columns has been studied qualitatively. Also, an array of copper micro-columns has been fabricated on stainless steel (SS-304) substrate for further exploration of LECD process capability.

Differential activation of cell death and autophagy results in an increased cytotoxic potential for trifluorothymidine compared to 5-fluorouracil in colon cancer cells.

PubMed

Bijnsdorp, Irene V; Peters, Godefridus J; Temmink, Olaf H; Fukushima, Masakazu; Kruyt, Frank A

2010-05-15

Trifluorothymidine (TFT) is part of the oral drug formulation TAS-102. Both 5-fluorouracil (5-FU) and TFT can inhibit thymidylate synthase and be incorporated into DNA. TFT shows only moderate cross-resistance to 5-FU. Therefore, we examined whether mechanistic differences in cell death could underlie their different modes of action in colorectal cancer cell lines (WiDR, Lovo92 and Colo320). Drug cytotoxicity was determined by SRB- and clonogenic assays, cell death by flow cytometry (PI and annexin V), caspase cleavage by Western blotting and activity assays and in vivo activity in the hollow fiber assay. The IC(50) values of TFT were 1-6 fold lower than for 5-FU, and clonogenic survival was less than 0.9% at 3 muM TFT, while 2-20% of the cells still survived after 20 muM 5-FU. In general, TFT was a more potent inducer of apoptosis than 5-FU, although the contribution of caspases varied between the used cell lines and necrosis-like cell death was detected. Accordingly, both drugs induced caspase (Z-VAD) independent cell death and lysosomal cathepsin B was involved. Activation of autophagy recovery mechanisms was only triggered by 5-FU, but not by TFT as determined by LC3B expression and cleavage. Inhibition of autophagy by 3-MA in 5-FU exposed cells reduced cell survival. Also, in vivo TFT (as TAS-102) caused more cell death than a 5-FU formulation. We conclude that TFT and 5-FU induce cell death via both caspase-dependent and independent mechanisms. The TFT was more potent than 5-FU, because it induces higher levels of cell death and does not elicit an autophagic survival response in the cancer cell lines. This provides a strong molecular basis for further application of TFT in cancer therapy.

Treatment of TFT-LCD wastewater containing ethanolamine by fluidized-bed Fenton technology.

PubMed

Anotai, Jin; Chen, Chia-Min; Bellotindos, Luzvisminda M; Lu, Ming-Chun

2012-06-01

The objectives of this study are: (1) to determine the effect of pH, initial concentration of Fe(2+) and H(2)O(2) dosage on the removal efficiency of MEA by fluidized-bed Fenton process and Fenton process, (2) to determine the optimal conditions for the degradation of ethanolamine from TFT-LCD wastewater by fluidized-bed Fenton process. In the design of experiment, the Box-Behnken design was used to optimize the operating conditions. A removal efficiency of 98.9% for 5mM MEA was achieved after 2h under optimal conditions of pH3, [Fe(2+)]=5mM and [H(2)O(2)]=60mM. Copyright © 2011 Elsevier Ltd. All rights reserved.

Laser micromachining of optical devices

NASA Astrophysics Data System (ADS)

Kopitkovas, Giedrius; Lippert, Thomas; David, Christian; Sulcas, Rokas; Hobley, Jonathan; Wokaun, Alexander J.; Gobrecht, Jens

2004-10-01

The combination of a gray tone phase mask with a laser assisted wet etching process was applied to fabricate complex microstructures in UV transparent dielectric materials. This one-step method allows the generation of arrays of plano-convex and Fresnel micro-lenses using a conventional XeCl excimer laser and an absorbing liquid, which is in contact with the UV transparent material. An array of plano-convex micro-lenses was tested as beam homogenizer for a high power XeCl excimer and ps Nd:YAG laser. The roughness of the etched features varies from several μm to 10 nm, depending on the laser fluence and concentration of the dye in the organic liquid. The etching process can be divided into several etching mechanisms which vary with laser fluence.

Effect of the spatial autocorrelation of empty sites on the evolution of cooperation

NASA Astrophysics Data System (ADS)

Zhang, Hui; Wang, Li; Hou, Dongshuang

2016-02-01

An evolutionary game model is constructed to investigate the spatial autocorrelation of empty sites on the evolution of cooperation. Each individual is assumed to imitate the strategy of the one who scores the highest in its neighborhood including itself. Simulation results illustrate that the evolutionary dynamics based on the Prisoner's Dilemma game (PD) depends severely on the initial conditions, while the Snowdrift game (SD) is hardly affected by that. A high degree of autocorrelation of empty sites is beneficial for the evolution of cooperation in the PD, whereas it shows diversification effects depending on the parameter of temptation to defect in the SD. Moreover, for the repeated game with three strategies, 'always defect' (ALLD), 'tit-for-tat' (TFT), and 'always cooperate' (ALLC), simulations reveal that an amazing evolutionary diversity appears for varying of parameters of the temptation to defect and the probability of playing in the next round of the game. The spatial autocorrelation of empty sites can have profound effects on evolutionary dynamics (equilibrium and oscillation) and spatial distribution.

Micro Computer Tomography for medical device and pharmaceutical packaging analysis.

PubMed

Hindelang, Florine; Zurbach, Raphael; Roggo, Yves

2015-04-10

Biomedical device and medicine product manufacturing are long processes facing global competition. As technology evolves with time, the level of quality, safety and reliability increases simultaneously. Micro Computer Tomography (Micro CT) is a tool allowing a deep investigation of products: it can contribute to quality improvement. This article presents the numerous applications of Micro CT for medical device and pharmaceutical packaging analysis. The samples investigated confirmed CT suitability for verification of integrity, measurements and defect detections in a non-destructive manner. Copyright © 2015 Elsevier B.V. All rights reserved.

The embryonic mir-35 family of microRNAs promotes multiple aspects of fecundity in Caenorhabditis elegans.

PubMed

McJunkin, Katherine; Ambros, Victor

2014-07-21

MicroRNAs guide many aspects of development in all metazoan species. Frequently, microRNAs are expressed during a specific developmental stage to perform a temporally defined function. The C. elegans mir-35-42 microRNAs are expressed abundantly in oocytes and early embryos and are essential for embryonic development. Here, we show that these embryonic microRNAs surprisingly also function to control the number of progeny produced by adult hermaphrodites. Using a temperature-sensitive mir-35-42 family mutant (a deletion of the mir-35-41 cluster), we demonstrate three distinct defects in hermaphrodite fecundity. At permissive temperatures, a mild sperm defect partially reduces hermaphrodite fecundity. At restrictive temperatures, somatic gonad dysfunction combined with a severe sperm defect sharply reduces fecundity. Multiple lines of evidence, including a late embryonic temperature-sensitive period, support a role for mir-35-41 early during development to promote subsequent sperm production in later larval stages. We further show that the predicted mir-35 family target sup-26 (suppressor-26) acts downstream of mir-35-41 in this process, suggesting that sup-26 de-repression in mir-35-41 deletion mutants may contribute to temperature-sensitive loss of fecundity. In addition, these microRNAs play a role in male fertility, promoting proper morphogenesis of male-specific mating structures. Overall, our results demonstrate that robust activity of the mir-35-42 family microRNAs not only is essential for embryonic development across a range of temperatures but also enables the worm to subsequently develop full reproductive capacity. Copyright © 2014 McJunkin and Ambros.

Enhancement in photo-electrochemical efficiency by reducing recombination rate in branched TiO2 nanotube array on functionalizing with ZnO micro crystals

NASA Astrophysics Data System (ADS)

Boda, Muzaffar Ahmad; Ashraf Shah, Mohammad

2018-06-01

In this study, branched TiO2 nanotube array were fabricated through electrochemical anodization process at constant voltage using third generation electrolyte. On account of morphological advantage, these nanotubes shows significant enhancement in photo-electrochemical property than compact or conventional titania nanotube array. However, their photo-electrochemical efficiency intensifies on coating with ZnO micro-crystals. ZnO coated branched TiO2 nanotube array shows a photocurrent density of 27.8 mA cm‑2 which is 1.55 times the photocurrent density (17.2 mA cm‑2) shown by bare branched titania nanotubes. The significant enhancement in photocurrent density shown by the resulting ZnO/TiO2 hybrid structure is attributed to suppression in electron–hole recombination phenomenon by offering smooth pathway to photo generated excitons on account of staggered band edge positions in individual semiconductors.

Performance improvement for solution-processed high-mobility ZnO thin-film transistors

NASA Astrophysics Data System (ADS)

Sha Li, Chen; Li, Yu Ning; Wu, Yi Liang; Ong, Beng S.; Loutfy, Rafik O.

2008-06-01

The fabrication technology of stable, non-toxic, transparent, high performance zinc oxide (ZnO) thin-film semiconductors via the solution process was investigated. Two methods, which were, respectively, annealing a spin-coated precursor solution and annealing a drop-coated precursor solution, were compared. The prepared ZnO thin-film semiconductor transistors have well-controlled, preferential crystal orientation and exhibit superior field-effect performance characteristics. But the ZnO thin-film transistor (TFT) fabricated by annealing a drop-coated precursor solution has a distinctly elevated linear mobility, which further approaches the saturated mobility, compared with that fabricated by annealing a spin-coated precursor solution. The performance of the solution-processed ZnO TFT was further improved when substituting the spin-coating process by the drop-coating process.

Defect analysis and detection of micro nano structured optical thin film

NASA Astrophysics Data System (ADS)

Xu, Chang; Shi, Nuo; Zhou, Lang; Shi, Qinfeng; Yang, Yang; Li, Zhuo

2017-10-01

This paper focuses on developing an automated method for detecting defects on our wavelength conversion thin film. We analyzes the operating principle of our wavelength conversion Micro/Nano thin film which absorbing visible light and emitting infrared radiation, indicates the relationship between the pixel's pattern and the radiation of the thin film, and issues the principle of defining blind pixels and their categories due to the calculated and experimental results. An effective method is issued for the automated detection based on wavelet transform and template matching. The results reveal that this method has desired accuracy and processing speed.

Development of a continuous roll-to-roll processing system for mass production of plastic optical film

NASA Astrophysics Data System (ADS)

Chang, Chih-Yuan; Tsai, Meng-Hsun

2015-12-01

This paper reports a highly effective method for the mass production of large-area plastic optical films with a microlens array pattern based on a continuous roll-to-roll film extrusion and roller embossing process. In this study, a thin steel mold with a micro-circular hole array pattern is fabricated by photolithography and a wet chemical etching process. The thin steel mold was then wrapped onto a metal cylinder to form an embossing roller mold. During the roll-to-roll process operation, a thermoplastic raw material (polycarbonate grains) was put into the barrel of the plastic extruder with a flat T-die. Then, the molten polymer film was extruded and immediately pressed against the surface of the embossing roller mold. Under the proper processing conditions, the molten polymer will just partially fill the micro-circular holes of the mold and due to surface tension form a convex lens surface. A continuous plastic optical film with a microlens array pattern was obtained. Experiments are carried out to investigate the effect of plastic microlens formation on the roll-to-roll process. Finally, the geometrical and optical properties of the fabricated plastic optical film were measured and proved satisfactory. This technique shows great potential for the mass production of large-area plastic optical films with a microlens array pattern.

Profiling Pre-MicroRNA and Mature MicroRNA Expressions Using a Single Microarray and Avoiding Separate Sample Preparation

PubMed Central

Gan, Lin; Denecke, Bernd

2013-01-01

Mature microRNA is a crucial component in the gene expression regulation network. At the same time, microRNA gene expression and procession is regulated in a precise and collaborated way. Pre-microRNAs mediate products during the microRNA transcription process, they can provide hints of microRNA gene expression regulation or can serve as alternative biomarkers. To date, little effort has been devoted to pre-microRNA expression profiling. In this study, three human and three mouse microRNA profile data sets, based on the Affymetrix miRNA 2.0 array, have been re-analyzed for both mature and pre-microRNA signals as a primary test of parallel mature/pre-microRNA expression profiling on a single platform. The results not only demonstrated a glimpse of pre-microRNA expression in human and mouse, but also the relationship of microRNA expressions between pre- and mature forms. The study also showed a possible application of currently available microRNA microarrays in profiling pre-microRNA expression in a time and cost effective manner. PMID:27605179

Fabrication of a stretchable solid-state micro-supercapacitor array.

PubMed

Kim, Daeil; Shin, Gunchul; Kang, Yu Jin; Kim, Woong; Ha, Jeong Sook

2013-09-24

We fabricated a stretchable micro-supercapacitor array with planar SWCNT electrodes and an ionic liquid-based triblock copolymer electrolyte. The mechanical stability of the entire supercapacitor array upon stretching was obtained by adopting strategic design concepts. First, the narrow and long serpentine metallic interconnections were encapsulated with polyimide thin film to ensure that they were within the mechanical neutral plane. Second, an array of two-dimensional planar micro-supercapacitor with SWCNT electrodes and an ion-gel-type electrolyte was made to achieve all-solid-state energy storage devices. The formed micro-supercapacitor array showed excellent performances which were stable over stretching up to 30% without any noticeable degradation. This work shows the strong potential of a stretchable micro-supercapacitor array in applications such as wearable computers, power dressing, electronic newspapers, paper-like mobile phones, and other easily collapsible gadgets.

Device and material characterization and analytic modeling of amorphous silicon thin film transistors

NASA Astrophysics Data System (ADS)

Slade, Holly Claudia

Hydrogenated amorphous silicon thin film transistors (TFTs) are now well-established as switching elements for a variety of applications in the lucrative electronics market, such as active matrix liquid crystal displays, two-dimensional imagers, and position-sensitive radiation detectors. These applications necessitate the development of accurate characterization and simulation tools. The main goal of this work is the development of a semi- empirical, analytical model for the DC and AC operation of an amorphous silicon TFT for use in a manufacturing facility to improve yield and maintain process control. The model is physically-based, in order that the parameters scale with gate length and can be easily related back to the material and device properties. To accomplish this, extensive experimental data and 2D simulations are used to observe and quantify non- crystalline effects in the TFTs. In particular, due to the disorder in the amorphous network, localized energy states exist throughout the band gap and affect all regimes of TFT operation. These localized states trap most of the free charge, causing a gate-bias-dependent field effect mobility above threshold, a power-law dependence of the current on gate bias below threshold, very low leakage currents, and severe frequency dispersion of the TFT gate capacitance. Additional investigations of TFT instabilities reveal the importance of changes in the density of states and/or back channel conduction due to bias and thermal stress. In the above threshold regime, the model is similar to the crystalline MOSFET model, considering the drift component of free charge. This approach uses the field effect mobility to take into account the trap states and must utilize the correct definition of threshold voltage. In the below threshold regime, the density of deep states is taken into account. The leakage current is modeled empirically, and the parameters are temperature dependent to 150oC. The capacitance of the TFT can be modeled using a transmission line model, which is implemented using a small signal circuit with access resistors in series with the source and drain capacitances. This correctly reproduces the frequency dispersion in the TFT. Automatic parameter extraction routines are provided and are used to test the robustness of the model on a variety of devices from different research laboratories. The results demonstrate excellent agreement, showing that the model is suitable for device design, scaling, and implementation in the manufacturing process.

Optimizing laser beam profiles using micro-lens arrays for efficient material processing: applications to solar cells

NASA Astrophysics Data System (ADS)

Hauschild, Dirk; Homburg, Oliver; Mitra, Thomas; Ivanenko, Mikhail; Jarczynski, Manfred; Meinschien, Jens; Bayer, Andreas; Lissotschenko, Vitalij

2009-02-01

High power laser sources are used in various production tools for microelectronic products and solar cells, including the applications annealing, lithography, edge isolation as well as dicing and patterning. Besides the right choice of the laser source suitable high performance optics for generating the appropriate beam profile and intensity distribution are of high importance for the right processing speed, quality and yield. For industrial applications equally important is an adequate understanding of the physics of the light-matter interaction behind the process. In advance simulations of the tool performance can minimize technical and financial risk as well as lead times for prototyping and introduction into series production. LIMO has developed its own software founded on the Maxwell equations taking into account all important physical aspects of the laser based process: the light source, the beam shaping optical system and the light-matter interaction. Based on this knowledge together with a unique free-form micro-lens array production technology and patented micro-optics beam shaping designs a number of novel solar cell production tool sub-systems have been built. The basic functionalities, design principles and performance results are presented with a special emphasis on resilience, cost reduction and process reliability.

High-Performance Visible-Blind Ultraviolet Photodetector Based on IGZO TFT Coupled with p-n Heterojunction.

PubMed

Yu, Jingjing; Javaid, Kashif; Liang, Lingyan; Wu, Weihua; Liang, Yu; Song, Anran; Zhang, Hongliang; Shi, Wen; Chang, Ting-Chang; Cao, Hongtao

2018-03-07

A visible-blind ultraviolet (UV) photodetector was designed based on a three-terminal electronic device of thin-film transistor (TFT) coupled with two-terminal p-n junction optoelectronic device, in hope of combining the beauties of both of the devices together. Upon the uncovered back-channel surface of amorphous indium-gallium-zinc-oxide (IGZO) TFT, we fabricated PEDOT:PSS/SnO x /IGZO heterojunction structure, through which the formation of a p-n junction and directional carrier transfer of photogenerated carriers were experimentally validated. As expected, the photoresponse characteristics of the newly designed photodetector, with a photoresponsivity of 984 A/W at a wavelength of 320 nm, a UV-visible rejection ratio up to 3.5 × 10 7 , and a specific detectivity up to 3.3 × 10 14 Jones, are not only competitive compared to the previous reports but also better than those of the pristine IGZO phototransistor. The hybrid photodetector could be operated in the off-current region with low supply voltages (<0.1 V) and ultralow power dissipation (<10 nW under illumination and ∼0.2 pW in the dark). Moreover, by applying a short positive gate pulse onto the gate, the annoying persistent photoconductivity presented in the wide band gap oxide-based devices could be suppressed conveniently, in hope of improving the response rate. With the terrific photoresponsivity along with the advantages of photodetecting pixel integration, the proposed phototransistor could be potentially used in high-performance visible-blind UV photodetector pixel arrays.

High- k Gate Dielectrics for Emerging Flexible and Stretchable Electronics.

PubMed

Wang, Binghao; Huang, Wei; Chi, Lifeng; Al-Hashimi, Mohammed; Marks, Tobin J; Facchetti, Antonio

2018-05-22

Recent advances in flexible and stretchable electronics (FSE), a technology diverging from the conventional rigid silicon technology, have stimulated fundamental scientific and technological research efforts. FSE aims at enabling disruptive applications such as flexible displays, wearable sensors, printed RFID tags on packaging, electronics on skin/organs, and Internet-of-things as well as possibly reducing the cost of electronic device fabrication. Thus, the key materials components of electronics, the semiconductor, the dielectric, and the conductor as well as the passive (substrate, planarization, passivation, and encapsulation layers) must exhibit electrical performance and mechanical properties compatible with FSE components and products. In this review, we summarize and analyze recent advances in materials concepts as well as in thin-film fabrication techniques for high- k (or high-capacitance) gate dielectrics when integrated with FSE-compatible semiconductors such as organics, metal oxides, quantum dot arrays, carbon nanotubes, graphene, and other 2D semiconductors. Since thin-film transistors (TFTs) are the key enablers of FSE devices, we discuss TFT structures and operation mechanisms after a discussion on the needs and general requirements of gate dielectrics. Also, the advantages of high- k dielectrics over low- k ones in TFT applications were elaborated. Next, after presenting the design and properties of high- k polymers and inorganic, electrolyte, and hybrid dielectric families, we focus on the most important fabrication methodologies for their deposition as TFT gate dielectric thin films. Furthermore, we provide a detailed summary of recent progress in performance of FSE TFTs based on these high- k dielectrics, focusing primarily on emerging semiconductor types. Finally, we conclude with an outlook and challenges section.

Fabrication of cell container arrays with overlaid surface topographies.

PubMed

Truckenmüller, Roman; Giselbrecht, Stefan; Escalante-Marun, Maryana; Groenendijk, Max; Papenburg, Bernke; Rivron, Nicolas; Unadkat, Hemant; Saile, Volker; Subramaniam, Vinod; van den Berg, Albert; van Blitterswijk, Clemens; Wessling, Matthias; de Boer, Jan; Stamatialis, Dimitrios

2012-02-01

This paper presents cell culture substrates in the form of microcontainer arrays with overlaid surface topographies, and a technology for their fabrication. The new fabrication technology is based on microscale thermoforming of thin polymer films whose surfaces are topographically prepatterned on a micro- or nanoscale. For microthermoforming, we apply a new process on the basis of temporary back moulding of polymer films and use the novel concept of a perforated-sheet-like mould. Thermal micro- or nanoimprinting is applied for prepatterning. The novel cell container arrays are fabricated from polylactic acid (PLA) films. The thin-walled microcontainer structures have the shape of a spherical calotte merging into a hexagonal shape at their upper circumferential edges. In the arrays, the cell containers are arranged densely packed in honeycomb fashion. The inner surfaces of the highly curved container walls are provided with various topographical micro- and nanopatterns. For a first validation of the microcontainer arrays as in vitro cell culture substrates, C2C12 mouse premyoblasts are cultured in containers with microgrooved surfaces and shown to align along the grooves in the three-dimensional film substrates. In future stem-cell-biological and tissue engineering applications, microcontainers fabricated using the proposed technology may act as geometrically defined artificial microenvironments or niches.

Optimizing operating parameters of a honeycomb zeolite rotor concentrator for processing TFT-LCD volatile organic compounds with competitive adsorption characteristics.

PubMed

Lin, Yu-Chih; Chang, Feng-Tang

2009-05-30

In this study, we attempted to enhance the removal efficiency of a honeycomb zeolite rotor concentrator (HZRC), operated at optimal parameters, for processing TFT-LCD volatile organic compounds (VOCs) with competitive adsorption characteristics. The results indicated that when the HZRC processed a VOCs stream of mixed compounds, compounds with a high boiling point take precedence in the adsorption process. In addition, existing compounds with a low boiling point adsorbed onto the HZRC were also displaced by the high-boiling-point compounds. In order to achieve optimal operating parameters for high VOCs removal efficiency, results suggested controlling the inlet velocity to <1.5m/s, reducing the concentration ratio to 8 times, increasing the desorption temperature to 200-225 degrees C, and setting the rotation speed to 6.5rpm.

Flexible phosphorescent OLEDs on metal foil for military and commercial applications

NASA Astrophysics Data System (ADS)

Chwang, Anna; Lu, JengPing; Shih, Chinwen; Tung, Yeh-Jiun; Hewitt, Richard; Hack, Michael; Ho, Jackson; Brown, Julie

2005-05-01

We report recent advances in the development of low power consumption, emissive, flexible active matrix displays through integration of top emitting phosphorescent OLED (T-PHOLED) and poly-Si TFT backplane technologies. The displays are fabricated on flexible stainless steel foil. The T-PHOLEDs are based on UDC phosphorescent OLED technology, and the backplane is based on PARC's Excimer Laser Annealed (ELA) poly-Si TFT process. We also present progress in operational lifetime of encapsulated T-PHOLED pixels on planarized metal foil and discuss PHOLED encapsulation strategy.

Fabrication of single crystalline stripe in Si and Ge film on rolled flexible glass substrate by UV cw micro-chevron laser beam

NASA Astrophysics Data System (ADS)

Yeh, Wenchang

2017-08-01

Micro chevron laser beam annealing (μCLBA) of Si film and Ge film were introduced. Single crystal stripe with a dimension of several tens to hundreds μm in length and 3-8μm in width was formed in Si film or Ge film by scanning μCLBA over the film. Main boundaries in the c-Si stripe were Σ3 CSL twin boundary. Scanning speed of micro linear laser beam annealing (μLLBA) was varied from 0.05 m/s to 8m/s to investigate its influence to crystallinity. Even at 8m/s lateral growth taken place, however, crystal quality was better for slower lateral growth. Crystallization area per energy (APE) of μLLBA was evaluated and compared with other methods. It was found APE of μLLBA was larger than other method, especially for a display with low fill factor of TFT, APE can be several orders of magnitude larger.

In vitro synergism of trifluorothymidine and ganciclovir against HSV-1.

PubMed

Hobden, Jeffery A; Kumar, Manish; Kaufman, Herbert E; Clement, Christian; Varnell, Emily D; Bhattacharjee, Partha S; Hill, James M

2011-02-01

To determine whether trifluorothymidine (TFT) and ganciclovir (GCV) are synergistic against herpes simplex virus type 1 (HSV-1). TFT and GCV activity against 12 strains of HSV-1 (including an acyclovir-resistant strain) was measured by plaque-forming unit (PFU) inhibition. Cellular toxicity was assessed with an MTT dye reduction assay. Synergism was determined by calculating fractional inhibitory concentration (FIC indices) based on PFU reduction. Concentrations of TFT resulting in 50% inhibition of PFUs (IC(50)) of acyclovir-susceptible HSV-1 strains ranged from 3.07 ± 0.36 to 12.52 ± 0.61 μM. GCV IC(50) values ranged from 0.40 ± 0.02 to 1.59 ± 0.14 μM. IC(50) values of TFT and GCV against the acyclovir-resistant strain were 15.40 ± 3.17 and 93.00 ± 9.64 μM, respectively. Concentrations of TFT or GCV resulting in 50% cell cytotoxicity (CC(50)) were 0.99 ± 0.01 and 92.91 ± 8.92 μM, respectively. TFT and GCV combined (10:1) were 10 times more potent against all acyclovir-susceptible HSV-1 strains. For 8 of 12 HSV-1 strains, the IC(50) of TFT and GCV combined was lower than the CC(50) of either drug. For acyclovir-susceptible HSV-1 strains, TFT and GCV combined generated a FIC index of <0.5, suggesting strong synergism between the two drugs. The FIC value for TFT and GCV combined against the acyclovir-resistant HSV-1 strain was 0.84, indicating nonantagonism. TFT and GCV are synergistic against acyclovir-susceptible HSV-1 at concentrations significantly less toxic than if each antiviral were used as a sole agent.

In Vitro Synergism of Trifluorothymidine and Ganciclovir against HSV-1

PubMed Central

Hobden, Jeffery A.; Kumar, Manish; Kaufman, Herbert E.; Clement, Christian; Varnell, Emily D.; Bhattacharjee, Partha S.

2011-01-01

Purpose. To determine whether trifluorothymidine (TFT) and ganciclovir (GCV) are synergistic against herpes simplex virus type 1 (HSV-1). Methods. TFT and GCV activity against 12 strains of HSV-1 (including an acyclovir-resistant strain) was measured by plaque-forming unit (PFU) inhibition. Cellular toxicity was assessed with an MTT dye reduction assay. Synergism was determined by calculating fractional inhibitory concentration (FIC indices) based on PFU reduction. Results. Concentrations of TFT resulting in 50% inhibition of PFUs (IC50) of acyclovir-susceptible HSV-1 strains ranged from 3.07 ± 0.36 to 12.52 ± 0.61 μM. GCV IC50 values ranged from 0.40 ± 0.02 to 1.59 ± 0.14 μM. IC50 values of TFT and GCV against the acyclovir-resistant strain were 15.40 ± 3.17 and 93.00 ± 9.64 μM, respectively. Concentrations of TFT or GCV resulting in 50% cell cytotoxicity (CC50) were 0.99 ± 0.01 and 92.91 ± 8.92 μM, respectively. TFT and GCV combined (10:1) were 10 times more potent against all acyclovir-susceptible HSV-1 strains. For 8 of 12 HSV-1 strains, the IC50 of TFT and GCV combined was lower than the CC50 of either drug. For acyclovir-susceptible HSV-1 strains, TFT and GCV combined generated a FIC index of <0.5, suggesting strong synergism between the two drugs. The FIC value for TFT and GCV combined against the acyclovir-resistant HSV-1 strain was 0.84, indicating nonantagonism. Conclusions. TFT and GCV are synergistic against acyclovir-susceptible HSV-1 at concentrations significantly less toxic than if each antiviral were used as a sole agent. PMID:20861476

Fabrication of micro-lens array on convex surface by meaning of micro-milling

NASA Astrophysics Data System (ADS)

Zhang, Peng; Du, Yunlong; Wang, Bo; Shan, Debin

2014-08-01

In order to develop the application of the micro-milling technology, and to fabricate ultra-precision optical surface with complex microstructure, in this paper, the primary experimental research on micro-milling complex microstructure array is carried out. A complex microstructure array surface with vary parameters is designed, and the mathematic model of the surface is set up and simulated. For the fabrication of the designed microstructure array surface, a micro three-axis ultra-precision milling machine tool is developed, aerostatic guideway drove directly by linear motor is adopted in order to guarantee the enough stiffness of the machine, and novel numerical control strategy with linear encoders of 5nm resolution used as the feedback of the control system is employed to ensure the extremely high motion control accuracy. With the help of CAD/CAM technology, convex micro lens array on convex spherical surface with different scales on material of polyvinyl chloride (PVC) and pure copper is fabricated using micro tungsten carbide ball end milling tool based on the ultra-precision micro-milling machine. Excellent nanometer-level micro-movement performance of the axis is proved by motion control experiment. The fabrication is nearly as the same as the design, the characteristic scale of the microstructure is less than 200μm and the accuracy is better than 1μm. It prove that ultra-precision micro-milling technology based on micro ultra-precision machine tool is a suitable and optional method for micro manufacture of microstructure array surface on different kinds of materials, and with the development of micro milling cutter, ultraprecision micro-milling complex microstructure surface will be achieved in future.

New PMOS LTPS TFT pixel for AMOLED to suppress the hysteresis effect on OLED current by employing a reset voltage driving

NASA Astrophysics Data System (ADS)

Lee, Jae-Hoon; Park, Sang-Geun; Han, Sang-Myeon; Han, Min-Koo; Park, Kee-Chan

2008-03-01

New PMOS LTPS (low temperature polycrystalline silicon)-thin film transistor (TFT) pixel circuit, which can suppress an OLED current error caused by the hysteresis of LTPS-TFT for active matrix organic light emitting diode (AMOLED) display, is proposed and fabricated. The proposed pixel circuit employs a reset voltage driving so that the sweep direction of gate voltage in the current driving TFT is not altered by the gate voltage in the previous frame. Our experimental results show that OLED current error of the proposed pixel is successfully suppressed because a reset voltage can enable the starting gate voltage for a desired one not to be varied, while that of the conventional 2-TFT pixel exceeds over 15% due to the hysteresis of LTPS-TFT.

Simple and rapid enzymatic method for the synthesis of single-strand oligonucleotides containing trifluorothymidine.

PubMed

Suzuki, Norihiko; Fukushima, Masakazu

2010-11-01

To investigate the mechanism of trifluorothymidine (TFT)-induced DNA damage, we developed an enzymatic method for the synthesis of single-strand oligonucleotides containing TFT-monophosphate residues. Sixteen-mer oligonucleotides and 14-mer 5'-phosphorylated oligonucleotides were annealed to the template of 25-mer, so as to empty one nucleotide site. TFT-triphosphate was incorporated into the site by DNA polymerase and then ligated to 5'-phosphorylated oligonucleotides by DNA ligase. The synthesized 31-mer oligonucleotides containing TFT residues were isolated from the 25-mer complementary template by denaturing polyacrylamide electrophoresis. Using these single-strand oligonucleotides containing TFT residues, the cleavage of TFT residues from DNA, using mismatch uracil-DNA glycosylase (MUG) of E.coli origin, was compared with that of 5-fluorouracil (5FU) and 5-bromodeoxyuridine (BrdU). The TFT/A pair was not cleaved by MUG, while the other pairs, namely, 5FU/A, 5FU/G, BrdU/A, BrdU/G, and TFT/G, were easily cleaved from each synthesized DNA. Thus, this method is useful for obtaining some site-specifically modified oligonucleotides.

Development of High-Performance eSWIR HgCdTe-Based Focal-Plane Arrays on Silicon Substrates

NASA Astrophysics Data System (ADS)

Park, J. H.; Pepping, J.; Mukhortova, A.; Ketharanathan, S.; Kodama, R.; Zhao, J.; Hansel, D.; Velicu, S.; Aqariden, F.

2016-09-01

We report the development of high-performance and low-cost extended short-wavelength infrared (eSWIR) focal-plane arrays (FPAs) fabricated from molecular beam epitaxial (MBE)-grown HgCdTe on Si-based substrates. High-quality n-type eSWIR HgCdTe (cutoff wavelength ˜2.68 μm at 77 K, electron carrier concentration 5.82 × 1015 cm-3) layers were grown on CdTe/Si substrates by MBE. High degrees of uniformity in composition and thickness were demonstrated over three-inch areas, and low surface defect densities (voids 9.56 × 101 cm-2, micro-defects 1.67 × 103 cm-2) were measured. This material was used to fabricate 320 × 256 format, 30 μm pitch FPAs with a planar device architecture using arsenic implantation to achieve p-type doping. The dark current density of test devices showed good uniformity between 190 K and room temperature, and high-quality eSWIR imaging from hybridized FPAs was obtained with a median dark current density of 2.63 × 10-7 A/cm2 at 193 K with a standard deviation of 1.67 × 10-7 A/cm2.

Correlation of lattice defects and thermal processing in the crystallization of titania nanotube arrays

NASA Astrophysics Data System (ADS)

Hosseinpour, Pegah M.; Yung, Daniel; Panaitescu, Eugen; Heiman, Don; Menon, Latika; Budil, David; Lewis, Laura H.

2014-12-01

Titania nanotubes have the potential to be employed in a wide range of energy-related applications such as solar energy-harvesting devices and hydrogen production. As the functionality of titania nanostructures is critically affected by their morphology and crystallinity, it is necessary to understand and control these factors in order to engineer useful materials for green applications. In this study, electrochemically-synthesized titania nanotube arrays were thermally processed in inert and reducing environments to isolate the role of post-synthesis processing conditions on the crystallization behavior, electronic structure and morphology development in titania nanotubes, correlated with the nanotube functionality. Structural and calorimetric studies revealed that as-synthesized amorphous nanotubes crystallize to form the anatase structure in a three-stage process that is facilitated by the creation of structural defects. It is concluded that processing in a reducing gas atmosphere versus in an inert environment provides a larger unit cell volume and a higher concentration of Ti3+ associated with oxygen vacancies, thereby reducing the activation energy of crystallization. Further, post-synthesis annealing in either reducing or inert atmospheres produces pronounced morphological changes, confirming that the nanotube arrays thermally transform into a porous morphology consisting of a fragmented tubular architecture surrounded by a network of connected nanoparticles. This study links explicit data concerning morphology, crystallization and defects, and shows that the annealing gas environment determines the details of the crystal structure, the electronic structure and the morphology of titania nanotubes. These factors, in turn, impact the charge transport and consequently the functionality of these nanotubes as photocatalysts.

Photo-Induced Room-Temperature Gas Sensing with a-IGZO Based Thin-Film Transistors Fabricated on Flexible Plastic Foil.

PubMed

Knobelspies, Stefan; Bierer, Benedikt; Daus, Alwin; Takabayashi, Alain; Salvatore, Giovanni Antonio; Cantarella, Giuseppe; Ortiz Perez, Alvaro; Wöllenstein, Jürgen; Palzer, Stefan; Tröster, Gerhard

2018-01-26

We present a gas sensitive thin-film transistor (TFT) based on an amorphous Indium-Gallium-Zinc-Oxide (a-IGZO) semiconductor as the sensing layer, which is fabricated on a free-standing flexible polyimide foil. The photo-induced sensor response to NO₂ gas at room temperature and the cross-sensitivity to humidity are investigated. We combine the advantages of a transistor based sensor with flexible electronics technology to demonstrate the first flexible a-IGZO based gas sensitive TFT. Since flexible plastic substrates prohibit the use of high operating temperatures, the charge generation is promoted with the help of UV-light absorption, which ultimately triggers the reversible chemical reaction with the trace gas. Furthermore, the device fabrication process flow can be directly implemented in standard TFT technology, allowing for the parallel integration of the sensor and analog or logical circuits.

Photo-Induced Room-Temperature Gas Sensing with a-IGZO Based Thin-Film Transistors Fabricated on Flexible Plastic Foil

PubMed Central

Bierer, Benedikt; Takabayashi, Alain; Ortiz Perez, Alvaro; Wöllenstein, Jürgen

2018-01-01

We present a gas sensitive thin-film transistor (TFT) based on an amorphous Indium–Gallium–Zinc–Oxide (a-IGZO) semiconductor as the sensing layer, which is fabricated on a free-standing flexible polyimide foil. The photo-induced sensor response to NO2 gas at room temperature and the cross-sensitivity to humidity are investigated. We combine the advantages of a transistor based sensor with flexible electronics technology to demonstrate the first flexible a-IGZO based gas sensitive TFT. Since flexible plastic substrates prohibit the use of high operating temperatures, the charge generation is promoted with the help of UV-light absorption, which ultimately triggers the reversible chemical reaction with the trace gas. Furthermore, the device fabrication process flow can be directly implemented in standard TFT technology, allowing for the parallel integration of the sensor and analog or logical circuits. PMID:29373524

Inverter Circuits Using ZnO Nanoparticle Based Thin-Film Transistors for Flexible Electronic Applications

PubMed Central

Vidor, Fábio F.; Meyers, Thorsten; Hilleringmann, Ulrich

2016-01-01

Innovative systems exploring the flexibility and the transparency of modern semiconducting materials are being widely researched by the scientific community and by several companies. For a low-cost production and large surface area applications, thin-film transistors (TFTs) are the key elements driving the system currents. In order to maintain a cost efficient integration process, solution based materials are used as they show an outstanding tradeoff between cost and system complexity. In this paper, we discuss the integration process of ZnO nanoparticle TFTs using a high-k resin as gate dielectric. The performance in dependence on the transistor structure has been investigated, and inverted staggered setups depict an improved performance over the coplanar device increasing both the field-effect mobility and the ION/IOFF ratio. Aiming at the evaluation of the TFT characteristics for digital circuit applications, inverter circuits using a load TFT in the pull-up network and an active TFT in the pull-down network were integrated. The inverters show reasonable switching characteristics and V/V gains. Conjointly, the influence of the geometry ratio and the supply voltage on the devices have been analyzed. Moreover, as all integration steps are suitable to polymeric templates, the fabrication process is fully compatible to flexible substrates. PMID:28335282

Inverter Circuits Using ZnO Nanoparticle Based Thin-Film Transistors for Flexible Electronic Applications.

PubMed

Vidor, Fábio F; Meyers, Thorsten; Hilleringmann, Ulrich

2016-08-23

Innovative systems exploring the flexibility and the transparency of modern semiconducting materials are being widely researched by the scientific community and by several companies. For a low-cost production and large surface area applications, thin-film transistors (TFTs) are the key elements driving the system currents. In order to maintain a cost efficient integration process, solution based materials are used as they show an outstanding tradeoff between cost and system complexity. In this paper, we discuss the integration process of ZnO nanoparticle TFTs using a high- k resin as gate dielectric. The performance in dependence on the transistor structure has been investigated, and inverted staggered setups depict an improved performance over the coplanar device increasing both the field-effect mobility and the I ON / I OFF ratio. Aiming at the evaluation of the TFT characteristics for digital circuit applications, inverter circuits using a load TFT in the pull-up network and an active TFT in the pull-down network were integrated. The inverters show reasonable switching characteristics and V / V gains. Conjointly, the influence of the geometry ratio and the supply voltage on the devices have been analyzed. Moreover, as all integration steps are suitable to polymeric templates, the fabrication process is fully compatible to flexible substrates.

Synergistic approach to high-performance oxide thin film transistors using a bilayer channel architecture.

PubMed

Yu, Xinge; Zhou, Nanjia; Smith, Jeremy; Lin, Hui; Stallings, Katie; Yu, Junsheng; Marks, Tobin J; Facchetti, Antonio

2013-08-28

We report here a bilayer metal oxide thin film transistor concept (bMO TFT) where the channel has the structure: dielectric/semiconducting indium oxide (In2O3) layer/semiconducting indium gallium oxide (IGO) layer. Both semiconducting layers are grown from solution via a low-temperature combustion process. The TFT mobilities of bottom-gate/top-contact bMO TFTs processed at T = 250 °C are ~5tmex larger (~2.6 cm(2)/(V s)) than those of single-layer IGO TFTs (~0.5 cm(2)/(V s)), reaching values comparable to single-layer combustion-processed In2O3 TFTs (~3.2 cm(2)/(V s)). More importantly, and unlike single-layer In2O3 TFTs, the threshold voltage of the bMO TFTs is ~0.0 V, and the current on/off ratio is significantly enhanced to ~1 × 10(8) (vs ~1 × 10(4) for In2O3). The microstructure and morphology of the In2O3/IGO bilayers are analyzed by X-ray diffraction, atomic force microscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy, revealing the polycrystalline nature of the In2O3 layer and the amorphous nature of the IGO layer. This work demonstrates that solution-processed metal oxides can be implemented in bilayer TFT architectures with significantly enhanced performance.

Thought Field Therapy Compared to Cognitive Behavioral Therapy and Wait-List for Agoraphobia: A Randomized, Controlled Study with a 12-Month Follow-up.

PubMed

Irgens, Audun C; Hoffart, Asle; Nysæter, Tor E; Haaland, Vegard Ø; Borge, Finn-Magnus; Pripp, Are H; Martinsen, Egil W; Dammen, Toril

2017-01-01

Background: Thought field therapy (TFT) is used for many psychiatric conditions, but its efficacy has not been sufficiently documented. Hence, there is a need for studies comparing TFT to well-established treatments. This study compares the efficacy of TFT and cognitive behavioral therapy (CBT) for patients with agoraphobia. Methods: Seventy-two patients were randomized to CBT ( N = 24), TFT ( N = 24) or a wait-list condition (WLC) ( N = 24) after a diagnostic procedure including the MINI PLUS that was performed before treatment or WLC. Following a 3 months waiting period, the WL patients were randomized to CBT ( n = 12) or TFT ( n = 12), and all patients were reassessed after treatment or waiting period and at 12 months follow-up. At first we compared the three groups CBT, TFT, and WL. After the post WL randomization, we compared CBT ( N = 12 + 24 = 36) to TFT ( N = 12 + 24 = 36), applying the pre-treatment scores as baseline for all patients. The primary outcome measure was a symptom score from the Anxiety Disorders Interview Scale that was performed by an interviewer blinded to the treatment condition. For statistical comparisons, we used the independent sample's t -test, the Fisher's exact test and the ANOVA and ANCOVA tests. Results: Both CBT and TFT showed better results than the WLC ( p < 0.001) at post-treatment. Post-treatment and at the 12-month follow-up, there were not significant differences between CBT and TFT ( p = 0.33 and p = 0.90, respectively). Conclusion: This paper reports the first study comparing TFT to CBT for any disorder. The study indicated that TFT may be an efficient treatment for patients with agoraphobia. Trial Registration: https://clinicaltrials.gov/, identifier NCT00932919.

Thought Field Therapy Compared to Cognitive Behavioral Therapy and Wait-List for Agoraphobia: A Randomized, Controlled Study with a 12-Month Follow-up

PubMed Central

Irgens, Audun C.; Hoffart, Asle; Nysæter, Tor E.; Haaland, Vegard Ø.; Borge, Finn-Magnus; Pripp, Are H.; Martinsen, Egil W.; Dammen, Toril

2017-01-01

Background: Thought field therapy (TFT) is used for many psychiatric conditions, but its efficacy has not been sufficiently documented. Hence, there is a need for studies comparing TFT to well-established treatments. This study compares the efficacy of TFT and cognitive behavioral therapy (CBT) for patients with agoraphobia. Methods: Seventy-two patients were randomized to CBT (N = 24), TFT (N = 24) or a wait-list condition (WLC) (N = 24) after a diagnostic procedure including the MINI PLUS that was performed before treatment or WLC. Following a 3 months waiting period, the WL patients were randomized to CBT (n = 12) or TFT (n = 12), and all patients were reassessed after treatment or waiting period and at 12 months follow-up. At first we compared the three groups CBT, TFT, and WL. After the post WL randomization, we compared CBT (N = 12 + 24 = 36) to TFT (N = 12 + 24 = 36), applying the pre-treatment scores as baseline for all patients. The primary outcome measure was a symptom score from the Anxiety Disorders Interview Scale that was performed by an interviewer blinded to the treatment condition. For statistical comparisons, we used the independent sample’s t-test, the Fisher’s exact test and the ANOVA and ANCOVA tests. Results: Both CBT and TFT showed better results than the WLC (p < 0.001) at post-treatment. Post-treatment and at the 12-month follow-up, there were not significant differences between CBT and TFT (p = 0.33 and p = 0.90, respectively). Conclusion: This paper reports the first study comparing TFT to CBT for any disorder. The study indicated that TFT may be an efficient treatment for patients with agoraphobia. Trial Registration: https://clinicaltrials.gov/, identifier NCT00932919. PMID:28676782

A solution-processed quaternary oxide system obtained at low-temperature using a vertical diffusion technique

PubMed Central

Yoon, Seokhyun; Kim, Si Joon; Tak, Young Jun; Kim, Hyun Jae

2017-01-01

We report a method for fabricating solution-processed quaternary In-Ga-Zn-O (IGZO) thin-film transistors (TFTs) at low annealing temperatures using a vertical diffusion technique (VDT). The VDT is a deposition process for spin-coating binary and ternary oxide layers consecutively and annealing at once. With the VDT, uniform and dense quaternary oxide layers were fabricated at lower temperatures (280 °C). Compared to conventional IGZO and ternary In-Zn-O (IZO) thin films, VDT IGZO thin film had higher density of the metal-oxide bonds and lower density of the oxygen vacancies. The field-effect mobility of VDT IGZO TFT increased three times with an improved stability under positive bias stress than IZO TFT due to the reduction in oxygen vacancies. Therefore, the VDT process is a simple method that reduces the processing temperature without any additional treatment for quaternary oxide semiconductors with uniform layers. PMID:28230088

A solution-processed quaternary oxide system obtained at low-temperature using a vertical diffusion technique

NASA Astrophysics Data System (ADS)

Yoon, Seokhyun; Kim, Si Joon; Tak, Young Jun; Kim, Hyun Jae

2017-02-01

We report a method for fabricating solution-processed quaternary In-Ga-Zn-O (IGZO) thin-film transistors (TFTs) at low annealing temperatures using a vertical diffusion technique (VDT). The VDT is a deposition process for spin-coating binary and ternary oxide layers consecutively and annealing at once. With the VDT, uniform and dense quaternary oxide layers were fabricated at lower temperatures (280 °C). Compared to conventional IGZO and ternary In-Zn-O (IZO) thin films, VDT IGZO thin film had higher density of the metal-oxide bonds and lower density of the oxygen vacancies. The field-effect mobility of VDT IGZO TFT increased three times with an improved stability under positive bias stress than IZO TFT due to the reduction in oxygen vacancies. Therefore, the VDT process is a simple method that reduces the processing temperature without any additional treatment for quaternary oxide semiconductors with uniform layers.

A solution-processed quaternary oxide system obtained at low-temperature using a vertical diffusion technique.

PubMed

Yoon, Seokhyun; Kim, Si Joon; Tak, Young Jun; Kim, Hyun Jae

2017-02-23

We report a method for fabricating solution-processed quaternary In-Ga-Zn-O (IGZO) thin-film transistors (TFTs) at low annealing temperatures using a vertical diffusion technique (VDT). The VDT is a deposition process for spin-coating binary and ternary oxide layers consecutively and annealing at once. With the VDT, uniform and dense quaternary oxide layers were fabricated at lower temperatures (280 °C). Compared to conventional IGZO and ternary In-Zn-O (IZO) thin films, VDT IGZO thin film had higher density of the metal-oxide bonds and lower density of the oxygen vacancies. The field-effect mobility of VDT IGZO TFT increased three times with an improved stability under positive bias stress than IZO TFT due to the reduction in oxygen vacancies. Therefore, the VDT process is a simple method that reduces the processing temperature without any additional treatment for quaternary oxide semiconductors with uniform layers.

Evaluation of resonating Si cantilevers sputter-deposited with AlN piezoelectric thin films for mass sensing applications

NASA Astrophysics Data System (ADS)

Sökmen, Ü.; Stranz, A.; Waag, A.; Ababneh, A.; Seidel, H.; Schmid, U.; Peiner, E.

2010-06-01

We report on a micro-machined resonator for mass sensing applications which is based on a silicon cantilever excited with a sputter-deposited piezoelectric aluminium nitride (AlN) thin film actuator. An inductively coupled plasma (ICP) cryogenic dry etching process was applied for the micro-machining of the silicon substrate. A shift in resonance frequency was observed, which was proportional to a mass deposited in an e-beam evaporation process on top. We had a mass sensing limit of 5.2 ng. The measurements from the cantilevers of the two arrays revealed a quality factor of 155-298 and a mass sensitivity of 120.34 ng Hz-1 for the first array, and a quality factor of 130-137 and a mass sensitivity of 104.38 ng Hz-1 for the second array. Furthermore, we managed to fabricate silicon cantilevers, which can be improved for the detection in the picogram range due to a reduction of the geometrical dimensions.

GaN-based micro-LED arrays on flexible substrates for optical cochlear implants

NASA Astrophysics Data System (ADS)

Goßler, Christian; Bierbrauer, Colin; Moser, Rüdiger; Kunzer, Michael; Holc, Katarzyna; Pletschen, Wilfried; Köhler, Klaus; Wagner, Joachim; Schwaerzle, Michael; Ruther, Patrick; Paul, Oliver; Neef, Jakob; Keppeler, Daniel; Hoch, Gerhard; Moser, Tobias; Schwarz, Ulrich T.

2014-05-01

Currently available cochlear implants are based on electrical stimulation of the spiral ganglion neurons. Optical stimulation with arrays of micro-sized light-emitting diodes (µLEDs) promises to increase the number of distinguishable frequencies. Here, the development of a flexible GaN-based micro-LED array as an optical cochlear implant is reported for application in a mouse model. The fabrication of 15 µm thin and highly flexible devices is enabled by a laser-based layer transfer process of the GaN-LEDs from sapphire to a polyimide-on-silicon carrier wafer. The fabricated 50 × 50 µm2 LEDs are contacted via conducting paths on both p- and n-sides of the LEDs. Up to three separate channels could be addressed. The probes, composed of a linear array of the said µLEDs bonded to the flexible polyimide substrate, are peeled off the carrier wafer and attached to flexible printed circuit boards. Probes with four µLEDs and a width of 230 µm are successfully implanted in the mouse cochlea both in vitro and in vivo. The LEDs emit 60 µW at 1 mA after peel-off, corresponding to a radiant emittance of 6 mW mm-2.

Acoustic emission linear pulse holography

DOEpatents

Collins, H.D.; Busse, L.J.; Lemon, D.K.

1983-10-25

This device relates to the concept of and means for performing Acoustic Emission Linear Pulse Holography, which combines the advantages of linear holographic imaging and Acoustic Emission into a single non-destructive inspection system. This unique system produces a chronological, linear holographic image of a flaw by utilizing the acoustic energy emitted during crack growth. The innovation is the concept of utilizing the crack-generated acoustic emission energy to generate a chronological series of images of a growing crack by applying linear, pulse holographic processing to the acoustic emission data. The process is implemented by placing on a structure an array of piezoelectric sensors (typically 16 or 32 of them) near the defect location. A reference sensor is placed between the defect and the array.

Effect of different lubricant eye gels on tear film thickness as measured with ultrahigh-resolution optical coherence tomography.

PubMed

Wozniak, Piotr A; Schmidl, Doreen; Bata, Ahmed M; Fondi, Klemens; Witkowska, Katarzyna J; Aranha Dos Santos, Valentin; Baar, Carina; Room, Kim I; Nepp, Johannes; Baumgartner, Isabella; Popa-Cherecheanu, Alina; Garhöfer, Gerhard; Werkmeister, René M; Schmetterer, Leopold

2017-06-01

To compare the effect of a single drop of different lubricant eye gels on tear film thickness (TFT) as measured with ultrahigh-resolution optical coherence tomography (UHR-OCT) in patients with mild-to-moderate dry eye disease (DED). The study followed a randomized, single-masked, observer-blinded parallel group design. Patients received a single dose of either unpreserved trehalose 3% + hyaluronic acid 0.15% (TH), hyaluronic acid 0.2% (HA) or polyethylene glycol 0.4% + propylene glycol 0.3% (PP) eye drops. In total, 60 patients were included and TFT was measured using a custom-built UHR-OCT system. The mean TFT at baseline was 3.5 ± 0.7 μm. There was a significant difference in the time-course of TFT between the three groups (p = 0.001 between groups). Ten minutes after instillation, TFT increased by 155.8 ± 86.6%, 65.7 ± 71.5% and 33.4 ± 19.6% in the PP, TH and HA group, respectively (p < 0.001 between groups). Thirty minutes after instillation, the effect of all three different agents on TFT was comparable. Sixty and 120 min after administration, a significant increase in TFT was only seen for the TH group, but not for the other products (60 min: p < 0.021 between groups; 120 min: p < 0.037 between groups). In conclusion, we observed differences in TFT after administration of the lubricant gels. Ten minutes after instillation, a pronounced increase in TFT was observed in all groups. As compared to the other products, the combination of trehalose 3% + hyaluronic acid 0.15% offers a significantly longer increase in TFT indicating for a longer residence time. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Individual dual-emitting CdS multi-branched nanowire arrays under various pumping powers

NASA Astrophysics Data System (ADS)

Guo, S.; Zhao, F. Y.; Li, Y.; Song, G. L.; Li, A.; Chai, K.; Liang, L.; Ma, Z.; Weller, D.; Liu, R. B.

2016-10-01

High-quality Tin doped Cadmium Sulfide (CdS) comb-like nanostructures have been synthesized by a simple in situ seeding chemical vapor deposition process. The color-tunable dual emission of these comb-like nanostructures is demonstrated by changing the excitation power intensity. In fact, the color-tunable emission is in principal due to the variation of the dual emission intensity, which is proven by photoluminescence spectra and real color photoluminescence charge-coupled device images. Especially for different parts in the nano comb, the emission color can be varied even under the same pumping power. This is mainly due to the difference in local structure. By comparison, the color variation was not observed in pure CdS multi-branched nanostructures. The lifetime results demonstrate that the green emission originate from the recombination of free excitons. The origin of red emission is from the recombination of the dopant-induced intrinsic or extrinsic defect states. These findings provide potential applications of laser assisted anti-counterfeit label and micro-size monitors.

Handheld colorimeter for determination of heavy metal concentrations

NASA Astrophysics Data System (ADS)

López Ruiz, N.; Ariza, M.; Martínez Olmos, A.; Vukovic, J.; Palma, A. J.; Capitan-Vallvey, L. F.

2011-08-01

A portable instrument that measures heavy metal concentration from a colorimetric sensor array is presented. The use of eight sensing membranes, placed on a plastic support, allows to obtain the hue component of the HSV colour space of each one in order to determinate the concentration of metals present in a solution. The developed microcontroller-based system captures, in an ambient light environment, an image of the sensor array using an integrated micro-camera and shows the picture in a touch micro-LCD screen which acts as user interface. After image-processing of the regions of interest selected by the user, colour and concentration information are displayed on the screen.

New approach in evaluation of ceramic-polymer composite bioactivity and biocompatibility.

PubMed

Borkowski, Leszek; Sroka-Bartnicka, Anna; Polkowska, Izabela; Pawlowska, Marta; Palka, Krzysztof; Zieba, Emil; Slosarczyk, Anna; Jozwiak, Krzysztof; Ginalska, Grazyna

2017-09-01

Regeneration of bone defects was promoted by a novel β-glucan/carbonate hydroxyapatite composite and characterized by Raman spectroscopy, microCT and electron microscopy. The elastic biomaterial with an apatite-forming ability was developed for bone tissue engineering and implanted into the critical-size defects of rabbits' tibiae. The bone repair process was analyzed on non-decalcified bone/implant sections during a 6-month regeneration period. Using spectroscopic methods, we were able to determine the presence of amides, lipids and assign the areas of newly formed bone tissue. Raman spectroscopy was also used to assess the chemical changes in the composite before and after the implantation process. SEM analyses showed the mineralization degree in the defect area and that the gap size decreased significantly. Microscopic images revealed that the implant debris were interconnected to the poorly mineralized inner side of a new bone tissue. Our study demonstrated that the composite may serve as a biocompatible background for collagen ingrowth and exhibits the advantages of applying Raman spectroscopy, SEM and microCT in studying these samples.

Effect of dual-dielectric hydrogen-diffusion barrier layers on the performance of low-temperature processed transparent InGaZnO thin-film transistors

NASA Astrophysics Data System (ADS)

Tari, Alireza; Wong, William S.

2018-02-01

Dual-dielectric SiOx/SiNx thin-film layers were used as back-channel and gate-dielectric barrier layers for bottom-gate InGaZnO (IGZO) thin-film transistors (TFTs). The concentration profiles of hydrogen, indium, gallium, and zinc oxide were analyzed using secondary-ion mass spectroscopy characterization. By implementing an effective H-diffusion barrier, the hydrogen concentration and the creation of H-induced oxygen deficiency (H-Vo complex) defects during the processing of passivated flexible IGZO TFTs were minimized. A bilayer back-channel passivation layer, consisting of electron-beam deposited SiOx on plasma-enhanced chemical vapor-deposition (PECVD) SiNx films, effectively protected the TFT active region from plasma damage and minimized changes in the chemical composition of the semiconductor layer. A dual-dielectric PECVD SiOx/PECVD SiNx gate-dielectric, using SiOx as a barrier layer, also effectively prevented out-diffusion of hydrogen atoms from the PECVD SiNx-gate dielectric to the IGZO channel layer during the device fabrication.

Room-Temperature-Processed Flexible Amorphous InGaZnO Thin Film Transistor.

PubMed

Xiao, Xiang; Zhang, Letao; Shao, Yang; Zhou, Xiaoliang; He, Hongyu; Zhang, Shengdong

2017-12-13

A room-temperature flexible amorphous indium-gallium-zinc oxide thin film transistor (a-IGZO TFT) technology is developed on plastic substrates, in which both the gate dielectric and passivation layers of the TFTs are formed by an anodic oxidation (anodization) technique. While the gate dielectric Al 2 O 3 is grown with a conventional anodization on an Al:Nd gate electrode, the channel passivation layer Al 2 O 3 is formed using a localized anodization technique. The anodized Al 2 O 3 passivation layer shows a superior passivation effect to that of PECVD SiO 2 . The room-temperature-processed flexible a-IGZO TFT exhibits a field-effect mobility of 7.5 cm 2 /V·s, a subthreshold swing of 0.44 V/dec, an on-off ratio of 3.1 × 10 8 , and an acceptable gate-bias stability with threshold voltage shifts of 2.65 and -1.09 V under positive gate-bias stress and negative gate-bias stress, respectively. Bending and fatigue tests confirm that the flexible a-IGZO TFT also has a good mechanical reliability, with electrical performances remaining consistent up to a strain of 0.76% as well as after 1200 cycles of fatigue testing.

Micro-Ring Structures Stabilize Microdroplets to Enable Long Term Spheroid Culture in 384 Hanging Drop Array Plates

PubMed Central

Hsiao, Amy Y.; Tung, Yi-Chung; Kuo, Chuan-Hsien; Mosadegh, Bobak; Bedenis, Rachel; Pienta, Kenneth J.; Takayama, Shuichi

2012-01-01

Using stereolithography, 20 different structural variations comprised of millimeter diameter holes surrounded by trenches, plateaus, or micro-ring structures were prepared and tested for their ability to stably hold arrays of microliter sized droplets within the structures over an extended period of time. The micro-ring structures were the most effective in stabilizing droplets against mechanical and chemical perturbations. After confirming the importance of micro-ring structures using rapid prototyping, we developed an injection molding tool for mass production of polystyrene 3D cell culture plates with an array of 384 such micro-ring surrounded through-hole structures. These newly designed and injection molded polystyrene 384 hanging drop array plates with micro-rings were stable and robust against mechanical perturbations as well as surface fouling-facilitated droplet spreading making them capable of long term cell spheroid culture of up to 22 days within the droplet array. This is a significant improvement over previously reported 384 hanging drop array plates which are susceptible to small mechanical shocks and could not reliably maintain hanging drops for longer than a few days. With enhanced droplet stability, the hanging drop array plates with micro-ring structures provide better platforms and open up new opportunities for high-throughput preparation of microscale 3D cell constructs for drug screening and cell analysis. PMID:22057945

Micro-ring structures stabilize microdroplets to enable long term spheroid culture in 384 hanging drop array plates.

PubMed

Hsiao, Amy Y; Tung, Yi-Chung; Kuo, Chuan-Hsien; Mosadegh, Bobak; Bedenis, Rachel; Pienta, Kenneth J; Takayama, Shuichi

2012-04-01

Using stereolithography, 20 different structural variations comprised of millimeter diameter holes surrounded by trenches, plateaus, or micro-ring structures were prepared and tested for their ability to stably hold arrays of microliter sized droplets within the structures over an extended period of time. The micro-ring structures were the most effective in stabilizing droplets against mechanical and chemical perturbations. After confirming the importance of micro-ring structures using rapid prototyping, we developed an injection molding tool for mass production of polystyrene 3D cell culture plates with an array of 384 such micro-ring surrounded through-hole structures. These newly designed and injection molded polystyrene 384 hanging drop array plates with micro-rings were stable and robust against mechanical perturbations as well as surface fouling-facilitated droplet spreading making them capable of long term cell spheroid culture of up to 22 days within the droplet array. This is a significant improvement over previously reported 384 hanging drop array plates which are susceptible to small mechanical shocks and could not reliably maintain hanging drops for longer than a few days. With enhanced droplet stability, the hanging drop array plates with micro-ring structures provide better platforms and open up new opportunities for high-throughput preparation of microscale 3D cell constructs for drug screening and cell analysis.

Real-time algorithm for acoustic imaging with a microphone array.

PubMed

Huang, Xun

2009-05-01

Acoustic phased array has become an important testing tool in aeroacoustic research, where the conventional beamforming algorithm has been adopted as a classical processing technique. The computation however has to be performed off-line due to the expensive cost. An innovative algorithm with real-time capability is proposed in this work. The algorithm is similar to a classical observer in the time domain while extended for the array processing to the frequency domain. The observer-based algorithm is beneficial mainly for its capability of operating over sampling blocks recursively. The expensive experimental time can therefore be reduced extensively since any defect in a testing can be corrected instantaneously.

Flexible amorphous oxide thin-film transistors on polyimide substrate for AMOLED

NASA Astrophysics Data System (ADS)

Xu, Zhiping; Li, Min; Xu, Miao; Zou, Jianhua; Gao, Zhuo; Pang, Jiawei; Guo, Ying; Zhou, Lei; Wang, Chunfu; Fu, Dong; Peng, Junbiao; Wang, Lei; Cao, Yong

2014-10-01

We report a flexible amorphous Lanthanide doped In-Zn-O (IZO) thin-film transistor (TFT) backplane on polyimide (PI) substrate. In order to de-bond the PI film from the glass carrier easily after the flexible AMOLED process, a special inorganic film is deposited on the glass before the PI film is coated. The TFT exhibited a field-effect mobility of 6.97 cm2V-1 s-1, a subthreshold swing of 0.248 V dec-1, and an Ion/Ioff ratio of 5.19×107, which is sufficient to drive the OLEDs.

Surface modification of a polyimide gate insulator with an yttrium oxide interlayer for aqueous-solution-processed ZnO thin-film transistors.

PubMed

Jang, Kwang-Suk; Wee, Duyoung; Kim, Yun Ho; Kim, Jinsoo; Ahn, Taek; Ka, Jae-Won; Yi, Mi Hye

2013-06-11

We report a simple approach to modify the surface of a polyimide gate insulator with an yttrium oxide interlayer for aqueous-solution-processed ZnO thin-film transistors. It is expected that the yttrium oxide interlayer will provide a surface that is more chemically compatible with the ZnO semiconductor than is bare polyimde. The field-effect mobility and the on/off current ratio of the ZnO TFT with the YOx/polyimide gate insulator were 0.456 cm(2)/V·s and 2.12 × 10(6), respectively, whereas the ZnO TFT with the polyimide gate insulator was inactive.

State of the art of fine patterned Si TFT

NASA Astrophysics Data System (ADS)

Noguchi, Takashi

2003-05-01

Performance and relating subject for fine patterned Si TFT (Thin Film Transistor) are reviewed and discussed from a viewpoint of device and/or fabrication process based on reported results. Poly-Si TFTs fabricated on glass using low-temperature process are studied extensively for the application to LCD (Liquid Crystal Display) or OLED (Organic Light Emitting Diode) Display. Currently, the research target for the TFT application is emphasized on the highly functional system on glass or the display on flexible substrate by adopting an effective crystallizing technique of SPC (Solid Phase Crystallization) or ELC (Excimer Laser Crystallization). Improvement of device characteristics such as an enhancement of carrier mobility has been studied intensively by enlarging the grain size. Reduction of the voltage and shrinkage of the device size are the trend of Si LSI, which arise a peculiar issue of uniformity or an anisotropy problem for the device characteristics in the large grained poly-Si film. Some trial approaches for solving the issues such as nucleation control for the grain growth or lateral grain growth are proposed, so far. By overcoming the issues, coming SOP (System on Panel) era using the Si TFTs is expected.

Efficient Suppression of Defects and Charge Trapping in High Density In-Sn-Zn-O Thin Film Transistor Prepared using Microwave-Assisted Sputter.

PubMed

Goh, Youngin; Ahn, Jaehan; Lee, Jeong Rak; Park, Wan Woo; Ko Park, Sang-Hee; Jeon, Sanghun

2017-10-25

Amorphous oxide semiconductor-based thin film transistors (TFTs) have been considered as excellent switching elements for driving active-matrix organic light-emitting diodes (AMOLED) owing to their high mobility and process compatibility. However, oxide semiconductors have inherent defects, causing fast transient charge trapping and device instability. For the next-generation displays such as flexible, wearable, or transparent displays, an active semiconductor layer with ultrahigh mobility and high reliability at low deposition temperature is required. Therefore, we introduced high density plasma microwave-assisted (MWA) sputtering method as a promising deposition tool for the formation of high density and high-performance oxide semiconductor films. In this paper, we present the effect of the MWA sputtering method on the defects and fast charge trapping in In-Sn-Zn-O (ITZO) TFTs using various AC device characterization methodologies including fast I-V, pulsed I-V, transient current, low frequency noise, and discharge current analysis. Using these methods, we were able to analyze the charge trapping mechanism and intrinsic electrical characteristics, and extract the subgap density of the states of oxide TFTs quantitatively. In comparison to conventional sputtered ITZO, high density plasma MWA-sputtered ITZO exhibits outstanding electrical performance, negligible charge trapping characteristics and low subgap density of states. High-density plasma MWA sputtering method has high deposition rate even at low working pressure and control the ion bombardment energy, resulting in forming low defect generation in ITZO and presenting high performance ITZO TFT. We expect the proposed high density plasma sputtering method to be applicable to a wide range of oxide semiconductor device applications.

Rail flaw sizing using conventional and phased array ultrasonic testing.

DOT National Transportation Integrated Search

2012-12-01

An approach to detecting and characterizing internal defects in rail through the use of phased array ultrasonic testing has shown the potential to reduce the risk of missed defects and improve transverse defect characterization. : Transportation Tech...

Autonomous microexplosives subsurface tracing system final report.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Engler, Bruce Phillip; Nogan, John; Melof, Brian Matthew

The objective of the autonomous micro-explosive subsurface tracing system is to image the location and geometry of hydraulically induced fractures in subsurface petroleum reservoirs. This system is based on the insertion of a swarm of autonomous micro-explosive packages during the fracturing process, with subsequent triggering of the energetic material to create an array of micro-seismic sources that can be detected and analyzed using existing seismic receiver arrays and analysis software. The project included investigations of energetic mixtures, triggering systems, package size and shape, and seismic output. Given the current absence of any technology capable of such high resolution mapping ofmore » subsurface structures, this technology has the potential for major impact on petroleum industry, which spends approximately $1 billion dollar per year on hydraulic fracturing operations in the United States alone.« less

Assessment of local variability by high-throughput e-beam metrology for prediction of patterning defect probabilities

NASA Astrophysics Data System (ADS)

Wang, Fuming; Hunsche, Stefan; Anunciado, Roy; Corradi, Antonio; Tien, Hung Yu; Tang, Peng; Wei, Junwei; Wang, Yongjun; Fang, Wei; Wong, Patrick; van Oosten, Anton; van Ingen Schenau, Koen; Slachter, Bram

2018-03-01

We present an experimental study of pattern variability and defectivity, based on a large data set with more than 112 million SEM measurements from an HMI high-throughput e-beam tool. The test case is a 10nm node SRAM via array patterned with a DUV immersion LELE process, where we see a variation in mean size and litho sensitivities between different unique via patterns that leads to a seemingly qualitative differences in defectivity. The large available data volume enables further analysis to reliably distinguish global and local CDU variations, including a breakdown into local systematics and stochastics. A closer inspection of the tail end of the distributions and estimation of defect probabilities concludes that there is a common defect mechanism and defect threshold despite the observed differences of specific pattern characteristics. We expect that the analysis methodology can be applied for defect probability modeling as well as general process qualification in the future.

The Trojan Female Technique for pest control: a candidate mitochondrial mutation confers low male fertility across diverse nuclear backgrounds in Drosophila melanogaster.

PubMed

Dowling, Damian K; Tompkins, Daniel M; Gemmell, Neil J

2015-10-01

Pest species represent a major ongoing threat to global biodiversity. Effective management approaches are required that regulate pest numbers, while minimizing collateral damage to nontarget species. The Trojan Female Technique (TFT) was recently proposed as a prospective approach to biological pest control. The TFT draws on the evolutionary hypothesis that maternally inherited mitochondrial genomes are prone to the accumulation of male, but not female, harming mutations. These mutations could be harnessed to provide trans-generational fertility-based control of pest species. A candidate TFT mutation was recently described in the fruit fly, Drosophila melanogaster, which confers male-only sterility in the specific isogenic nuclear background in which it is maintained. However, applicability of the TFT relies on mitochondrial mutations whose male-sterilizing effects are general across nuclear genomic contexts. We test this assumption, expressing the candidate TFT-mutation bearing haplotype alongside a range of nuclear backgrounds and comparing its fertility in males, relative to that of control haplotypes. We document consistently lower fertility for males harbouring the TFT mutation, in both competitive and noncompetitive mating contexts, across all nuclear backgrounds screened. This indicates that TFT mutations conferring reduced male fertility can segregate within populations and could be harnessed to facilitate this novel form of pest control.

The Trojan Female Technique for pest control: a candidate mitochondrial mutation confers low male fertility across diverse nuclear backgrounds in Drosophila melanogaster

PubMed Central

Dowling, Damian K; Tompkins, Daniel M; Gemmell, Neil J

2015-01-01

Pest species represent a major ongoing threat to global biodiversity. Effective management approaches are required that regulate pest numbers, while minimizing collateral damage to nontarget species. The Trojan Female Technique (TFT) was recently proposed as a prospective approach to biological pest control. The TFT draws on the evolutionary hypothesis that maternally inherited mitochondrial genomes are prone to the accumulation of male, but not female, harming mutations. These mutations could be harnessed to provide trans-generational fertility-based control of pest species. A candidate TFT mutation was recently described in the fruit fly, Drosophila melanogaster, which confers male-only sterility in the specific isogenic nuclear background in which it is maintained. However, applicability of the TFT relies on mitochondrial mutations whose male-sterilizing effects are general across nuclear genomic contexts. We test this assumption, expressing the candidate TFT-mutation bearing haplotype alongside a range of nuclear backgrounds and comparing its fertility in males, relative to that of control haplotypes. We document consistently lower fertility for males harbouring the TFT mutation, in both competitive and noncompetitive mating contexts, across all nuclear backgrounds screened. This indicates that TFT mutations conferring reduced male fertility can segregate within populations and could be harnessed to facilitate this novel form of pest control. PMID:26495040

Design and optimization of the micro-engine turbine rotor manufacturing using the rapid prototyping technology

NASA Astrophysics Data System (ADS)

Vdovin, R. A.; Smelov, V. G.

2017-02-01

This work describes the experience in manufacturing the turbine rotor for the micro-engine. It demonstrates the design principles for the complex investment casting process combining the use of the ProCast software and the rapid prototyping techniques. At the virtual modelling stage, in addition to optimized process parameters, the casting structure was improved to obtain the defect-free section. The real production stage allowed demonstrating the performance and fitness of rapid prototyping techniques for the manufacture of geometrically-complex engine-building parts.

Laser ablation for membrane processing of AlGaN/GaN- and micro structured ferroelectric thin film MEMS and SiC pressure sensors for extreme conditions

NASA Astrophysics Data System (ADS)

Zehetner, J.; Vanko, G.; Dzuba, J.; Ryger, I.; Lalinsky, T.; Benkler, Manuel; Lucki, Michal

2015-05-01

AlGaN/GaN based high electron mobility transistors (HEMTs), Schottky diodes and/or resistors have been presented as sensing devices for mechanical or chemical sensors operating in extreme conditions. In addition we investigate ferroelectric thin films for integration into micro-electro-mechanical-systems (MEMS). Creation of appropriate diaphragms and/or cantilevers out of SiC is necessary for further improvement of sensing properties of such MEMS sensors. For example sensitivity of the AlGaN/GaN based MEMS pressure sensor can be modified by membrane thickness. We demonstrated that a 4H-SiC 80μm thick diaphragms can be fabricated much faster with laser ablation than by electrochemical, photochemical or reactive ion etching (RIE). We were able to verify the feasibility of this process by fabrication of micromechanical membrane structures also in bulk 3C-SiC, borosilicate glass, sapphire and Al2O3 ceramic substrates by femtosecond laser (520nm) ablation. On a 350μm thick 4H-SiC substrate we produced an array of 275μm deep and 1000μm to 3000μm of diameter blind holes without damaging the 2μm AlN layer at the back side. In addition we investigated ferroelectric thin films as they can be deposited and micro-patterned by a direct UV-lithography method after the ablation process for a specific membrane design. The risk to harm or damage the function of thin films was eliminated by that means. Some defects in the ablated membranes are also affected by the polarisation of the laser light. Ripple structures oriented perpendicular to the laser polarisation promote creation of pin holes which would perforate a thin membrane. We developed an ablation technique strongly inhibiting formation of ripples and pin poles.

Fabrication and Testing of a Modular Micro-Pocket Fission Detector Instrumentation System for Test Nuclear Reactors

NASA Astrophysics Data System (ADS)

Reichenberger, Michael A.; Nichols, Daniel M.; Stevenson, Sarah R.; Swope, Tanner M.; Hilger, Caden W.; Roberts, Jeremy A.; Unruh, Troy C.; McGregor, Douglas S.

2018-01-01

Advancements in nuclear reactor core modeling and computational capability have encouraged further development of in-core neutron sensors. Measurement of the neutron-flux distribution within the reactor core provides a more complete understanding of the operating conditions in the reactor than typical ex-core sensors. Micro-Pocket Fission Detectors have been developed and tested previously but have been limited to single-node operation and have utilized highly specialized designs. The development of a widely deployable, multi-node Micro-Pocket Fission Detector assembly will enhance nuclear research capabilities. A modular, four-node Micro-Pocket Fission Detector array was designed, fabricated, and tested at Kansas State University. The array was constructed from materials that do not significantly perturb the neutron flux in the reactor core. All four sensor nodes were equally spaced axially in the array to span the fuel-region of the reactor core. The array was filled with neon gas, serving as an ionization medium in the small cavities of the Micro-Pocket Fission Detectors. The modular design of the instrument facilitates the testing and deployment of numerous sensor arrays. The unified design drastically improved device ruggedness and simplified construction from previous designs. Five 8-mm penetrations in the upper grid plate of the Kansas State University TRIGA Mk. II research nuclear reactor were utilized to deploy the array between fuel elements in the core. The Micro-Pocket Fission Detector array was coupled to an electronic support system which has been specially developed to support pulse-mode operation. The Micro-Pocket Fission Detector array composed of four sensors was used to monitor local neutron flux at a constant reactor power of 100 kWth at different axial locations simultaneously. The array was positioned at five different radial locations within the core to emulate the deployment of multiple arrays and develop a 2-dimensional measurement of neutron flux in the reactor core.

FPGA Control System for the Automated Test of Microshutters

NASA Technical Reports Server (NTRS)

Lyness, Eric; Rapchun, David A.; Moseley, S. Harvey

2008-01-01

The James Webb Space Telescope, scheduled to replace the Hubble in 2013, must simultaneously observe hundreds of faint galaxies. This requirement has led to the development of a programmable transmission mask which can be adapted to admit light with arbitrary pattern of galaxies into its spectrograph. This programmable mask will contain a large array of micro-electromechanical (MEMs) devices called MicroShutters. These microscopic shutters physically open and close like the shutter on a camera, except each shutter is microscopic in size and an array 365 by 171 is used to select the objects under spectroscopic observation at a given time, and to block the unwanted background light from other areas. NASA developed and is currently refining the exceptionally difficult process of manufacturing these shutters. This paper describes how the authors used LabVIEW FPGA and a reconfigurable I/O board to control the shutters in a test chamber and how the flexibility of the system allows us to continue to modify the control algorithms as NASA optimizes the performance of the MicroShutter arrays.

The Design of Distributed Micro Grid Energy Storage System

NASA Astrophysics Data System (ADS)

Liang, Ya-feng; Wang, Yan-ping

2018-03-01

Distributed micro-grid runs in island mode, the energy storage system is the core to maintain the micro-grid stable operation. For the problems that it is poor to adjust at work and easy to cause the volatility of micro-grid caused by the existing energy storage structure of fixed connection. In this paper, an array type energy storage structure is proposed, and the array type energy storage system structure and working principle are analyzed. Finally, the array type energy storage structure model is established based on MATLAB, the simulation results show that the array type energy storage system has great flexibility, which can maximize the utilization of energy storage system, guarantee the reliable operation of distributed micro-grid and achieve the function of peak clipping and valley filling.

Enhancing the imaging quality and fabrication efficiency of bionic compound eyes using a sandwich structure

NASA Astrophysics Data System (ADS)

Luo, Jiasai; Guo, Yongcai; Wang, Xin

2018-06-01

This paper puts forward a novel method for fabrication of sandwich-structured BCE using a detachable micro-hole array (MHA) prepared by 3D printing. Compared with most traditional methods, 3D printing enables effective implementation of direct micro-fabrication for curved BCE without the pattern transfer and substrate reshaping process. This 3D fabrication method allows rapid fabrication of the curved BCE and automatic assembly of the detachable MHA using a custom-built mold under negative pressure. The formation of a multi-focusing micro-lens array (MLA) was realized by adjusting the parameters of the curved detachable MHA. The imaging performance was effectively enhanced by the sandwich structure that consist of the multi-focusing MLA, the outer detachable MHA and the inner solidified MHA. This method is suitable for mass production due to its advantages as a time-saving, cost-effective and simple process. Optical design software was used to analyze the optical properties, and an imaging simulation was performed.

A Novel Method of Newborn Chest Compression: A Randomized Crossover Simulation Study.

PubMed

Smereka, Jacek; Szarpak, Lukasz; Ladny, Jerzy R; Rodriguez-Nunez, Antonio; Ruetzler, Kurt

2018-01-01

Objective: To compare a novel two-thumb chest compression technique with standard techniques during newborn resuscitation performed by novice physicians in terms of median depth of chest compressions, degree of full chest recoil, and effective compression efficacy. Patients and Methods: The total of 74 novice physicians with less than 1-year work experience participated in the study. They performed chest compressions using three techniques: (A) The new two-thumb technique (nTTT). The novel method of chest compressions in an infant consists in using two thumbs directed at the angle of 90° to the chest while closing the fingers of both hands in a fist. (B) TFT. With this method, the rescuer compresses the sternum with the tips of two fingers. (C) TTHT. Two thumbs are placed over the lower third of the sternum, with the fingers encircling the torso and supporting the back. Results: The median depth of chest compressions for nTTT was 3.8 (IQR, 3.7-3.9) cm, for TFT-2.1 (IQR, 1.7-2.5) cm, while for TTHT-3.6 (IQR, 3.5-3.8) cm. There was a significant difference between nTTT and TFT, and TTHT and TFT ( p < 0.001) for each time interval during resuscitation. The degree of full chest recoil was 93% (IQR, 91-97) for nTTT, 99% (IQR, 96-100) for TFT, and 90% (IQR, 74-91) for TTHT. There was a statistically significant difference in the degree of complete chest relaxation between nTTT and TFT ( p < 0.001), between nTTT and TTHT ( p = 0.016), and between TFT and TTHT ( p < 0.001). Conclusion: The median chest compression depth for nTTT and TTHT is significantly higher than that for TFT. The degree of full chest recoil was highest for TFT, then for nTTT and TTHT. The effective compression efficiency with nTTT was higher than for TTHT and TFT. Our novel newborn chest compression method in this manikin study provided adequate chest compression depth and degree of full chest recoil, as well as very good effective compression efficiency. Further clinical studies are necessary to confirm these initial results.

Atom-by-atom assembly of defect-free one-dimensional cold atom arrays.

PubMed

Endres, Manuel; Bernien, Hannes; Keesling, Alexander; Levine, Harry; Anschuetz, Eric R; Krajenbrink, Alexandre; Senko, Crystal; Vuletic, Vladan; Greiner, Markus; Lukin, Mikhail D

2016-11-25

The realization of large-scale fully controllable quantum systems is an exciting frontier in modern physical science. We use atom-by-atom assembly to implement a platform for the deterministic preparation of regular one-dimensional arrays of individually controlled cold atoms. In our approach, a measurement and feedback procedure eliminates the entropy associated with probabilistic trap occupation and results in defect-free arrays of more than 50 atoms in less than 400 milliseconds. The technique is based on fast, real-time control of 100 optical tweezers, which we use to arrange atoms in desired geometric patterns and to maintain these configurations by replacing lost atoms with surplus atoms from a reservoir. This bottom-up approach may enable controlled engineering of scalable many-body systems for quantum information processing, quantum simulations, and precision measurements. Copyright © 2016, American Association for the Advancement of Science.

Vertical Root Fracture initiation in curved roots after root canal preparation: A dentinal micro-crack analysis with LED transillumination

PubMed Central

Martín-Biedma, Benjamín; Varela-Patiño, Purificación; Ruíz-Piñón, Manuel; Castelo-Baz, Pablo

2017-01-01

Background One of the causative factors of root defects is the increased friction produced by rotary instrumentation. A high canal curvature may increase stress, making the tooth more susceptible to dentinal cracks. The purpose of this study was to evaluate dentinal micro-crack formation with the ProTaper NEXT and ProTaper Universal systems using LED transillumination, and to analyze the micro-crack generated at the point of maximum canal curvature. Material and Methods 60 human mandibular premolars with curvatures between 30–49° and radii between 2–4 mm were used. The root canals were instrumented using the Protaper Universal® and Protaper NEXT® systems, with the aid of the Proglider® system. The obtained samples were sectioned transversely before subsequent analysis with LED transillumination at 2 mm and 8 mm from the apex and at the point of maximum canal curvature. Defects were scored: 0 for no defects; and 1 for micro-cracks. Results Root defects were not observed in the control group. The ProTaper NEXT system caused fewer defects (16.7%) than the ProTaper Universal system (40%) (P<0.05). The ProTaper Universal system caused significantly more micro-cracks at the point of maximum canal curvature than the ProTaper NEXT system (P<0.05). Conclusions Rotary instrumentation systems often generate root defects, but the ProTaper NEXT system generated fewer dentinal defects than the ProTaper Universal system. A higher prevalence of defects was found at the point of maximum curvature in the ProTaper Universal group. Key words:Curved root, Micro-crack, point of maximum canal curvature, ProTaper NEXT, ProTaper Universal, Vertical root fracture. PMID:29167712

Tumoral micro-blood vessels and vascular microenvironment in human astrocytic tumors. A transmission electron microscopy study.

PubMed

Arismendi-Morillo, Gabriel; Castellano, Alan

2005-07-01

The development of peritumoral edema is thought to be due to extravasation of plasma water and macromolecules through a defective blood-brain barrier (BBB), but the exact mechanism by which occurs is poorly understood. The aim of this study was analyze at submicroscopic level the morphological changes in both micro-blood vessels and vascular microenvironment of astrocytic tumors in an attempt of understanding the pathological aspects that may help in the future researches for the design of future therapeutic strategies. Biopsies of 25 patients with pathological diagnosis of astrocytic tumors were examined with the transmission electron microscope. Both open and close tight junctions were observed in the micro-blood vessels, inclusive in a same tumor. Cytoskeletal disorganization associated with disintegrated perijunctional actin filaments were seen. The paracellular space showed enlargement and commonly occupied by fluid proteinaceous, endothelial cells display oncotic and ischemic changes, basal lamina reveals enlargement, edema, vacuolization and collagen fibers disposed in irregular array. Pericytes exhibited edema and phagocytoced material, astrocytic perivascular-feet showed signs of oncosis and necrosis, co-option vessels totally surrounding by neoplastic cells also were seen. The ultrastructural abnormalities observed in both junctional complexes and vascular microenvironment suggest a multi-factorial pathobiology process, probably hypoxia intratumoral, calcium overload in endothelial cells, and degradative effects of metalloproteinases over the basal membrane appear as determinant factors that leading to structural modifications of junctional complexes, therefore, treatment with both HIF-1alpha and metalloproteinases inhibitors possibly can contribute with the pharmacological handling of the peritumoral edema associated with astrocytic tumors.

TAS-102 for Treatment of Advanced Colorectal Cancers That Are No Longer Responding to Other Therapies.

PubMed

van der Velden, Daphne L; Opdam, Frans L; Voest, Emile E

2016-06-15

TAS-102 is a novel oral formulation of trifluridine (TFT) and tipiracil hydrochloride (TPI), a thymidine phosphorylase inhibitor. TFT was originally synthesized in the 1960s and is a nucleoside analogue that impedes DNA synthesis by inhibition of thymidylate synthase. TFT's main mechanism of action, however, seems to be its incorporation into DNA, which distinguishes TFT from current well-known antimetabolites like 5-fluorouracil (5-FU). The rapid degradation of TFT brought initial clinical development to a halt, but TFT reentered clinical trials when addition of a TPI was found to improve the bioavailability of TFT. The combined TFT-TPI formulation was tested in patients with treatment-refractory metastatic colorectal cancer in the randomized phase III RECOURSE study. Compared with placebo, TAS-102 was associated with an overall survival (OS) and progression-free survival (PFS) benefit and a 32% reduction in risk of death [median OS, 7.1 (95% CI, 6.5-7.8) vs. 5.3 months (95% CI, 4.6-6.0); median PFS, 2.0 (95% CI, 1.9-2.1) vs. 1.7 months (95% CI, 1.7-1.8); HR for death, 0.68 (95% CI, 0.58-0.81, P < 0.001)]. Based on the results of this pivotal trial and supported by results from an earlier phase II study, TAS-102 recently gained FDA approval. This article reviews the development of TAS-102 and its therapeutic value for the proposed indication. Clin Cancer Res; 22(12); 2835-9. ©2016 AACR. ©2016 American Association for Cancer Research.

Electro-pumped whispering gallery mode ZnO microlaser array

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, G. Y.; State Key Laboratory of Bioelectronics, School of Electronic Science and Engineering, Southeast University, Nanjing 210096; Li, J. T.

2015-01-12

By employing vapor-phase transport method, ZnO microrods are fabricated and directly assembled on p-GaN substrate to form a heterostructural microlaser array, which avoids of the relatively complicated etching process comparing previous work. Under applied forward bias, whispering gallery mode ZnO ultraviolet lasing is obtained from the as-fabricated heterostructural microlaser array. The device's electroluminescence originates from three distinct electron-hole recombination processes in the heterojunction interface, and whispering gallery mode ultraviolet lasing is obtained when the applied voltage is beyond the lasing threshold. This work may present a significant step towards future fabrication of a facile technique for micro/nanolasers.

Scaling up a tobacco control intervention in low resource settings: a case example for school teachers in India.

PubMed

Pednekar, M S; Nagler, E M; Gupta, P C; Pawar, P S; Mathur, N; Adhikari, K; Codeira, L S; Stoddard, A M; Sorensen, G

2018-06-01

Research on processes of bringing effective tobacco control interventions to scale to increase quit rates among tobacco users is uncommon. This study examines processes to bring to scale one such intervention for school teachers, i.e. Tobacco Free Teacher-Tobacco Free Society (TFT-TFS). This intervention provides a foundation for an effective and low cost approach to promote cessation through schools. The present study was conducted in the states of Bihar and Maharashtra in 2014 using quantitative and qualitative methods. Focus group discussions (FGDs) were analysed using immersion crystallization method. The data presented are from a survey of 291 principals and seven FGDs. This study examined characteristics of principals and teachers, organizational environment, external environmental factors and program characteristics to determine facilitators and barriers for successful dissemination and implementation of the TFT-TFS program. Some facilitators were, incorporation of the program in existing channels like staff meetings and trainings, certification and recognition by the department of education; while some barriers were routine time bound duties (mainly teaching) of teachers and prevalence of tobacco use among teachers and administrators. Principals and teachers expressed a need and high level of interest in the adoption and implementation of the TFT-TFS program in their schools.

The ergonomics approach for thin film transistor-liquid crystal display manufacturing process.

PubMed

Lu, Chih-Wei; Yao, Chia-Chun; Kuo, Chein-Wen

2012-01-01

The thin film transistor-liquid crystal display (TFT-LCD) has been used all over the world. Although the manufacture process of TFT-LCD was highly automated, employees are hired to do manual job in module assembly process. The operators may have high risk of musculoskeletal disorders because of the long work hours and the repetitive activities in an unfitted work station. The tools of this study were questionnaire, checklist and to evaluate the work place design. The result shows that the participants reported high musculoskeletal disorder symptoms in shoulder (59.8%), neck (49.5%), wrist (39.5%), and upper back (30.6%). And, to reduce the ergonomic risk factors, revising the height of the work benches, chairs and redesigning the truck to decrease the chance of unsuitable positions were recommended and to reduce other ergonomics hazards and seta good human machine interface and appropriate job design.

Fully integrated micro-separator with soft-magnetic micro-pillar arrays for filtrating lymphocytes.

PubMed

Dong, Tao; Su, Qianhua; Yang, Zhaochu; Karlsen, Frank; Jakobsen, Henrik; Egeland, Eirik Bentzen; Hjelseth, Snorre

2010-01-01

A fully integrated micro-separator with soft-magnetic micro-pillar arrays has been developed, which merely employs one independent Lab-On-Chip to realize the lymphocytes isolation from the human whole blood. The simulation, fabrication and experiment are executed to realize this novel microseparator. The simulation results show that, the soft-magnetic micro-pillars array can amplify and redistribute the electromagnetic field generated by the microcoils. The tests certify desirable separation efficiency can be realized using this new separator at low current. No extra cooling system is required for such a micro-separator. This micro-separator can also be used to separate other target cells or particles with the same principle.

Characterization of few-layered graphene grown by carbon implantation

NASA Astrophysics Data System (ADS)

Lee, Kin Kiong; McCallum, Jeffrey C.; Jamieson, David N.

2014-02-01

Graphene is considered to be a very promising material for applications in nanotechnology. The properties of graphene are strongly dependent on defects that occur during growth and processing. These defects can be either detrimental or beneficial to device performance depending on defect type, location and device application. Here we present experimental results on formation of few-layered graphene by carbon ion implantation into nickel films and characteristics of graphene devices formed by graphene transfer and lithographic patterning. Micro-Raman spectroscopy was used to determine the number of graphene layers formed and identify defects arising from the device processing. The graphene films were cleaned by annealing in vacuum. Transport properties of cleaned graphene films were investigated by fabrication of back-gated field-effect transistors, which exhibited high hole and electron mobility of 1935 and 1905 cm2/Vs, respectively.

Effect of friction stir welding parameters on defect formation

NASA Astrophysics Data System (ADS)

Tarasov, S. Yu.; Rubtsov, V. E.; Eliseev, A. A.; Kolubaev, E. A.; Filippov, A. V.; Ivanov, A. N.

2015-10-01

Friction stir welding is a perspective method for manufacturing automotive parts, aviation and space technology. One of the major problems is the formation of welding defects and weld around the welding zone. The formation of defect is the main reason failure of the joint. A possible way to obtain defect-free welded joints is the selection of the correct welding parameters. Experimental results describing the effect of friction stir welding process parameters on the defects of welded joints on aluminum alloy AMg5M have been shown. The weld joint defects have been characterized using the non-destructive radioscopic and ultrasound phase array methods. It was shown how the type and size of defects determine the welded joint strength.

Copper vertical micro dendrite fin arrays and their superior boiling heat transfer capability

NASA Astrophysics Data System (ADS)

Wang, Ya-Qiao; Lyu, Shu-Shen; Luo, Jia-Li; Luo, Zhi-Yong; Fu, Yuan-Xiang; Heng, Yi; Zhang, Jian-Hui; Mo, Dong-Chuan

2017-11-01

Micro pin fin arrays have been widely used in electronic cooling, micro reactors, catalyst support, and wettability modification and so on, and a facile way to produce better micro pin fin arrays is demanded. Herein, a simple electrochemical method has been developed to fabricate copper vertical micro dendrite fin arrays (Cu-VMDFA) with controllable shapes, number density and height. High copper sulphate concentration is one key point to make the dendrite stand vertically. Besides, the applied current should rise at an appropriate rate to ensure the copper dendrite can grow vertically on its own. The Cu-VMDFA can significantly enhance the heat transfer coefficient by approximately twice compared to the plain copper surface. The Cu-VMDFA may be widely used in boiling heat transfer areas such as nuclear power plants, electronic cooling, heat exchangers, and so on.

Large-scale fabrication of micro-lens array by novel end-fly-cutting-servo diamond machining.

PubMed

Zhu, Zhiwei; To, Suet; Zhang, Shaojian

2015-08-10

Fast/slow tool servo (FTS/STS) diamond turning is a very promising technique for the generation of micro-lens array (MLA). However, it is still a challenge to process MLA in large scale due to certain inherent limitations of this technique. In the present study, a novel ultra-precision diamond cutting method, as the end-fly-cutting-servo (EFCS) system, is adopted and investigated for large-scale generation of MLA. After a detailed discussion of the characteristic advantages for processing MLA, the optimal toolpath generation strategy for the EFCS is developed with consideration of the geometry and installation pose of the diamond tool. A typical aspheric MLA over a large area is experimentally fabricated, and the resulting form accuracy, surface micro-topography and machining efficiency are critically investigated. The result indicates that the MLA with homogeneous quality over the whole area is obtained. Besides, high machining efficiency, extremely small volume of control points for the toolpath, and optimal usage of system dynamics of the machine tool during the whole cutting can be simultaneously achieved.

The numerical simulation and experiment on extrusion roller embossing of light diffusion plate with micro-structure

NASA Astrophysics Data System (ADS)

Zang, Gongzheng; Fu, Zhihong; Zhang, Lei; Wan, Yue

2018-01-01

Extrusion roller embossing process has demonstrated the ability to produce polymer film with micro-structure. However the influence of various parameters on the forming quality has not been understood clearly. In this paper, a light diffusion plate with semi cylindrical micro-structure array as the research object, the influence of the main processing parameters such as roller speed, pressuring distance and polymer film temperature to the rolling quality was investigated in detail by simulation and experimental methods. The results show that the thickness of the light diffusion plate and the micro-structure fitting diameter increases with the increasing of the roll speed and the polymer film temperature, and decreases with the increasing of the pressing distance. Besides, the simulation results conformed well to the experimental results.

Low-cost composite blades for the Mod-0A wind turbines

NASA Technical Reports Server (NTRS)

Weingart, O.

1982-01-01

Low cost approaches to the design and fabrication of blades for a two-bladed 200 kW wind turbine were identified and the applicability of the techniques to larger and smaller blades was assessed. Blade tooling was designed and fabricated. Two complete blades and a partial blade for tool tryout were built. The patented TFT process was used to wind the entire blade. This process allows rapid winding of an axially oriented composite onto a tapered mandrel, with tapered wall thickness. The blade consists of a TFT glass-epoxy airfoil structure filament wound onto a steel root end fitting. The fitting is, in turn, bolted to a conical steel adapter section to provide for mounting attachment to the hub. Structural analysis, blade properties, and cost and weight analysis are described.

Periodically pulsed wet annealing approach for low-temperature processable amorphous InGaZnO thin film transistors with high electrical performance and ultrathin thickness

PubMed Central

Kim, Ye Kyun; Ahn, Cheol Hyoun; Yun, Myeong Gu; Cho, Sung Woon; Kang, Won Jun; Cho, Hyung Koun

2016-01-01

In this paper, a simple and controllable “wet pulse annealing” technique for the fabrication of flexible amorphous InGaZnO thin film transistors (a-IGZO TFTs) processed at low temperature (150 °C) by using scalable vacuum deposition is proposed. This method entailed the quick injection of water vapor for 0.1 s and purge treatment in dry ambient in one cycle; the supply content of water vapor was simply controlled by the number of pulse repetitions. The electrical transport characteristics revealed a remarkable performance of the a-IGZO TFTs prepared at the maximum process temperature of 150 °C (field-effect mobility of 13.3 cm2 V−1 s−1; Ion/Ioff ratio ≈ 108; reduced I-V hysteresis), comparable to that of a-IGZO TFTs annealed at 350 °C in dry ambient. Upon analysis of the angle-resolved x-ray photoelectron spectroscopy, the good performance was attributed to the effective suppression of the formation of hydroxide and oxygen-related defects. Finally, by using the wet pulse annealing process, we fabricated, on a plastic substrate, an ultrathin flexible a-IGZO TFT with good electrical and bending performances. PMID:27198067

Periodically pulsed wet annealing approach for low-temperature processable amorphous InGaZnO thin film transistors with high electrical performance and ultrathin thickness.

PubMed

Kim, Ye Kyun; Ahn, Cheol Hyoun; Yun, Myeong Gu; Cho, Sung Woon; Kang, Won Jun; Cho, Hyung Koun

2016-05-20

In this paper, a simple and controllable "wet pulse annealing" technique for the fabrication of flexible amorphous InGaZnO thin film transistors (a-IGZO TFTs) processed at low temperature (150 °C) by using scalable vacuum deposition is proposed. This method entailed the quick injection of water vapor for 0.1 s and purge treatment in dry ambient in one cycle; the supply content of water vapor was simply controlled by the number of pulse repetitions. The electrical transport characteristics revealed a remarkable performance of the a-IGZO TFTs prepared at the maximum process temperature of 150 °C (field-effect mobility of 13.3 cm(2) V(-1) s(-1); Ion/Ioff ratio ≈ 10(8); reduced I-V hysteresis), comparable to that of a-IGZO TFTs annealed at 350 °C in dry ambient. Upon analysis of the angle-resolved x-ray photoelectron spectroscopy, the good performance was attributed to the effective suppression of the formation of hydroxide and oxygen-related defects. Finally, by using the wet pulse annealing process, we fabricated, on a plastic substrate, an ultrathin flexible a-IGZO TFT with good electrical and bending performances.

Dual-gate photo thin-film transistor: a “smart” pixel for high- resolution and low-dose X-ray imaging

NASA Astrophysics Data System (ADS)

Wang, Kai; Ou, Hai; Chen, Jun

2015-06-01

Since its emergence a decade ago, amorphous silicon flat panel X-ray detector has established itself as a ubiquitous platform for an array of digital radiography modalities. The fundamental building block of a flat panel detector is called a pixel. In all current pixel architectures, sensing, storage, and readout are unanimously kept separate, inevitably compromising resolution by increasing pixel size. To address this issue, we hereby propose a “smart” pixel architecture where the aforementioned three components are combined in a single dual-gate photo thin-film transistor (TFT). In other words, the dual-gate photo TFT itself functions as a sensor, a storage capacitor, and a switch concurrently. Additionally, by harnessing the amplification effect of such a thin-film transistor, we for the first time created a single-transistor active pixel sensor. The proof-of-concept device had a W/L ratio of 250μm/20μm and was fabricated using a simple five-mask photolithography process, where a 130nm transparent ITO was used as the top photo gate, and a 200nm amorphous silicon as the absorbing channel layer. The preliminary results demonstrated that the photocurrent had been increased by four orders of magnitude due to light-induced threshold voltage shift in the sub-threshold region. The device sensitivity could be simply tuned by photo gate bias to specifically target low-level light detection. The dependence of threshold voltage on light illumination indicated that a dynamic range of at least 80dB could be achieved. The "smart" pixel technology holds tremendous promise for developing high-resolution and low-dose X-ray imaging and may potentially lower the cancer risk imposed by radiation, especially among paediatric patients.

Inhibition of HeLa cell growth by doxorubicin-loaded and tuftsin-conjugated arginate-PEG microparticles.

PubMed

Hu, Tianmu; Qahtan, Anwar Saeed Ahmed; Lei, Lei; Lei, Zhixin; Zhao, Dapeng; Nie, Hemin

2018-03-01

In order to improve the release pattern of chemotherapy drug and reduce the possibility of drug resistance, poly(ethylene glycol amine) (PEG)-modified alginate microparticles (ALG-PEG MPs) were developed then two different mechanisms were employed to load doxorubicin (Dox): 1) forming Dox/ALG-PEG complex by electrostatic attractions between unsaturated functional groups in Dox and ALG-PEG; 2) forming Dox-ALG-PEG complex through EDC-reaction between the amino and carboxyl groups in Dox and ALG, respectively. Additionally, tuftsin (TFT), a natural immunomodulation peptide, was conjugated to MPs in order to enhance the efficiency of cellular uptake. It was found that the Dox-ALG-PEG-TFT MPs exhibited a significantly slower release of Dox than Dox/ALG-PEG-TFT MPs in neutral medium, suggesting the role of covalent bonding in prolonging Dox retention. Besides, the release of Dox from these MPs was pH-sensitive, and the release rate was observably increased at pH 6.5 compared to the case at pH 7.4. Compared with Dox/ALG-PEG MPs and Dox-ALG-PEG MPs, their counterparts further conjugated with TFT more efficiently inhibited the growth of HeLa cells over a period of 48 h, implying the effectiveness of TFT in enhancing cellular uptake of MPs. Over a period of 48 h, Dox-ALG-PEG-TFT MPs inhibited the growth of HeLa cells less efficiently than Dox/ALG-PEG-TFT MPs but the difference was not significant ( p  > 0.05). In consideration of the prolonged and sustained release of Dox, Dox-ALG-PEG-TFT MPs possess the advantages for long-term treatment.

Controlled Defects of Fluorine-incorporated ZnO Nanorods for Photovoltaic Enhancement

PubMed Central

Lee, Hock Beng; Ginting, Riski Titian; Tan, Sin Tee; Tan, Chun Hui; Alshanableh, Abdelelah; Oleiwi, Hind Fadhil; Yap, Chi Chin; Jumali, Mohd Hafizuddin Hj.; Yahaya, Muhammad

2016-01-01

Anion passivation effect on metal-oxide nano-architecture offers a highly controllable platform for improving charge selectivity and extraction, with direct relevance to their implementation in hybrid solar cells. In current work, we demonstrated the incorporation of fluorine (F) as an anion dopant to address the defect-rich nature of ZnO nanorods (ZNR) and improve the feasibility of its role as electron acceptor. The detailed morphology evolution and defect engineering on ZNR were studied as a function of F-doping concentration (x). Specifically, the rod-shaped arrays of ZnO were transformed into taper-shaped arrays at high x. A hypsochromic shift was observed in optical energy band gap due to the Burstein-Moss effect. A substantial suppression on intrinsic defects in ZnO lattice directly epitomized the novel role of fluorine as an oxygen defect quencher. The results show that 10-FZNR/P3HT device exhibited two-fold higher power conversion efficiency than the pristine ZNR/P3HT device, primarily due to the reduced Schottky defects and charge transfer barrier. Essentially, the reported findings yielded insights on the functions of fluorine on (i) surface –OH passivation, (ii) oxygen vacancies (Vo) occupation and (iii) lattice oxygen substitution, thereby enhancing the photo-physical processes, carrier mobility and concentration of FZNR based device. PMID:27587295

Micro-computed Tomography Provides High Accuracy Congenital Heart Disease Diagnosis in Neonatal and Fetal Mice

PubMed Central

Kim, Andrew J.; Francis, Richard; Liu, Xiaoqin; Devine, William A.; Ramirez, Ricardo; Anderton, Shane J.; Wong, Li Yin; Faruque, Fahim; Gabriel, George C.; Leatherbury, Linda; Tobita, Kimimasa; Lo, Cecilia W.

2013-01-01

Background Mice are well suited for modeling human congenital heart defects (CHD), given their four-chamber cardiac anatomy. However, mice with CHD invariably die prenatally/neonatally, causing CHD phenotypes to be missed. Therefore, we investigated the efficacy of noninvasive micro-computed tomography (micro-CT) to screen for CHD in stillborn/fetal mice. These studies were carried out using chemically mutagenized mice expected to be enriched for birth defects including CHD. Methods and Results Stillborn/fetal mice obtained from the breeding of N-ethyl-N-nitrosourea (ENU) mutagenized mice were formalin-fixed and stained with iodine, then micro-CT scanned. Those diagnosed with CHD and some CHD-negative pups were necropsied. A subset of these were further analyzed by histopathology to confirm the CHD/no-CHD diagnosis. Micro-CT scanning of 2105 fetal/newborn mice revealed an abundance of ventricular septal defects (VSD) (n=307). Overall, we observed an accuracy of 89.8% for VSD diagnosis. Outflow tract anomalies identified by micro-CT included double outlet right ventricle (n=36), transposition of the great arteries (n=14), and persistent truncus arteriosus (n=3). These were diagnosed with a 97.4% accuracy. Aortic arch anomalies also were readily detected with an overall 99.6% accuracy. This included right aortic arch (n=28) and coarctation/interrupted aortic arch (n=12). Also detected by micro-CT were atrioventricular septal defects (n=22), tricuspid hypoplasia/atresia (n=13), and coronary artery fistulas (n=16). They yielded accuracies of 98.9%, 100%, and 97.8% respectively. Conclusions Contrast enhanced micro-CT imaging in neonatal/fetal mice can reliably detect a wide spectrum of CHD. We conclude micro-CT imaging can be used for routine rapid assessments of structural heart defects in fetal/newborn mice. PMID:23759365

Visualization and automatic detection of defect distribution in GaN atomic structure from sampling Moiré phase.

PubMed

Wang, Qinghua; Ri, Shien; Tsuda, Hiroshi; Kodera, Masako; Suguro, Kyoichi; Miyashita, Naoto

2017-09-19

Quantitative detection of defects in atomic structures is of great significance to evaluating product quality and exploring quality improvement process. In this study, a Fourier transform filtered sampling Moire technique was proposed to visualize and detect defects in atomic arrays in a large field of view. Defect distributions, defect numbers and defect densities could be visually and quantitatively determined from a single atomic structure image at low cost. The effectiveness of the proposed technique was verified from numerical simulations. As an application, the dislocation distributions in a GaN/AlGaN atomic structure in two directions were magnified and displayed in Moire phase maps, and defect locations and densities were detected automatically. The proposed technique is able to provide valuable references to material scientists and engineers by checking the effect of various treatments for defect reduction. © 2017 IOP Publishing Ltd.

Effective elastic moduli of triangular lattice material with defects

NASA Astrophysics Data System (ADS)

Liu, Xiaoyu; Liang, Naigang

2012-10-01

This paper presents an attempt to extend homogenization analysis for the effective elastic moduli of triangular lattice materials with microstructural defects. The proposed homogenization method adopts a process based on homogeneous strain boundary conditions, the micro-scale constitutive law and the micro-to-macro static operator to establish the relationship between the macroscopic properties of a given lattice material to its micro-discrete behaviors and structures. Further, the idea behind Eshelby's equivalent eigenstrain principle is introduced to replace a defect distribution by an imagining displacement field (eigendisplacement) with the equivalent mechanical effect, and the triangular lattice Green's function technique is developed to solve the eigendisplacement field. The proposed method therefore allows handling of different types of microstructural defects as well as its arbitrary spatial distribution within a general and compact framework. Analytical closed-form estimations are derived, in the case of the dilute limit, for all the effective elastic moduli of stretch-dominated triangular lattices containing fractured cell walls and missing cells, respectively. Comparison with numerical results, the Hashin-Shtrikman upper bounds and uniform strain upper bounds are also presented to illustrate the predictive capability of the proposed method for lattice materials. Based on this work, we propose that not only the effective Young's and shear moduli but also the effective Poisson's ratio of triangular lattice materials depend on the number density of fractured cell walls and their spatial arrangements.

Transport processes in magnetically confined plasmas in the nonlinear regime.

PubMed

Sonnino, Giorgio

2006-06-01

A field theory approach to transport phenomena in magnetically confined plasmas is presented. The thermodynamic field theory (TFT), previously developed for treating the generic thermodynamic system out of equilibrium, is applied to plasmas physics. Transport phenomena are treated here as the effect of the field linking the thermodynamic forces with their conjugate flows combined with statistical mechanics. In particular, the Classical and the Pfirsch-Schluter regimes are analyzed by solving the thermodynamic field equations of the TFT in the weak-field approximation. We found that, the TFT does not correct the expressions of the ionic heat fluxes evaluated by the neoclassical theory in these two regimes. On the other hand, the fluxes of matter and electronic energy (heat flow) is further enhanced in the nonlinear Classical and Pfirsch-Schluter regimes. These results seem to be in line with the experimental observations. The complete set of the electronic and ionic transport equations in the nonlinear Banana regime, is also reported. A paper showing the comparison between our theoretic results and the experimental observations in the JET machine is currently in preparation.

Fluorine and oxygen plasma influence on nanoparticle formation and aggregation in metal oxide thin film transistors

NASA Astrophysics Data System (ADS)

MÄ dzik, Mateusz; Elamurugu, Elangovan; Viegas, Jaime

2017-03-01

Despite recent advances in metal oxide thin-film transistor technology, there are no foundry processes available yet for large-scale deployment of metal oxide electronics and photonics, in a similar way as found for silicon based electronics and photonics. One of the biggest challenges of the metal oxide platform is the stability of the fabricated devices. Also, there is wide dispersion on the measured specifications of fabricated TFT, from lot-to-lot and from different research groups. This can be partially explained by the importance of the deposition method and its parameters, which determine thin film microstructure and thus its electrical properties. Furthermore, substrate pretreatment is an important factor, as it may act as a template for material growth. Not so often mentioned, plasma processes can also affect the morphology of deposited films on further deposition steps, such as inducing nanoparticle formation, which strongly impact the conduction mechanism in the channel layer of the TFT. In this study, molybdenum doped indium oxide is sputtered onto ALD deposited HfO2 with or without pattering, and etched by RIE chlorine based processing. Nanoparticle formation is observed when photoresist is removed by oxygen plasma ashing. HfO2 etching in CF4/Ar plasma prior to resist stripping in oxygen plasma promotes the aggregation of nanoparticles into nanosized branched structures. Such nanostructuring is absent when oxygen plasma steps are replaced by chemical wet processing with acetone. Finally, in order to understand the electronic transport effect of the nanoparticles on metal oxide thin film transistors, TFT have been fabricated and electrically characterized.

Direct laser writing for micro-optical devices using a negative photoresist.

PubMed

Tsutsumi, Naoto; Hirota, Junichi; Kinashi, Kenji; Sakai, Wataru

2017-12-11

Direct laser writing (DLW) via two-photon absorption (TPA) has attracted much attention as a new microfabrication technique because it can be applied to fabricate complex, three-dimensional (3D) microstructures. In this study, 3D microstructures and micro-optical devices of micro-lens array on the micrometer scale are fabricated using the negative photoresist SU-8 through TPA with a femtosecond laser pulse under a microscope. The effects of the irradiation conditions on linewidths, such as laser power, writing speed, and writing cycles (a number of times a line is overwritten), are investigated before the fabrication of the 3D microstructures. Various microstructures such as woodpiles, hemisphere and microstructures, 3D micro-lens and micro-lens array for micro-optical devices are fabricated. The shape of the micro-lens is evaluated using the shape analysis mode of a laser microscope to calculate the working distance of the fabricated micro-lenses. The calculated working distance corresponds well to the experimentally measured value. The focusing performance of the fabricated micro-lens is confirmed by the TPA fluorescence of an isopropyl thioxanthone (ITX) ethanol solution excited by a Ti:sapphire femtosecond laser at 800 nm. Micro-lens array (assembled 9 micro-lenses) are fabricated. Nine independent woodpile structures are simultaneously manufactured by DLW via TPA to confirm the multi-focusing ability using the fabricated micro-lens array.

Liquid micro-lens array activated by selective electrowetting on lithium niobate substrates.

PubMed

Grilli, S; Miccio, L; Vespini, V; Finizio, A; De Nicola, S; Ferraro, Pietro

2008-05-26

Lens effect was obtained in an open microfluidic system by using a thin layer of liquid on a polar electric crystal like LiNbO3. An array of liquid micro-lenses was generated by electrowetting effect in pyroelectric periodically poled crystals. Compared to conventional electrowetting devices, the pyroelectric effect allowed to have an electrode-less and circuit-less configuration. An interferometric technique was used to characterize the curvature of the micro-lenses and the corresponding results are presented and discussed. The preliminary results concerning the imaging capability of the micro-lens array are also reported.

Optimization of pulsed laser deposited ZnO thin-film growth parameters for thin-film transistors (TFT) application

NASA Astrophysics Data System (ADS)

Gupta, Manisha; Chowdhury, Fatema Rezwana; Barlage, Douglas; Tsui, Ying Yin

2013-03-01

In this work we present the optimization of zinc oxide (ZnO) film properties for a thin-film transistor (TFT) application. Thin films, 50±10 nm, of ZnO were deposited by Pulsed Laser Deposition (PLD) under a variety of growth conditions. The oxygen pressure, laser fluence, substrate temperature and annealing conditions were varied as a part of this study. Mobility and carrier concentration were the focus of the optimization. While room-temperature ZnO growths followed by air and oxygen annealing showed improvement in the (002) phase formation with a carrier concentration in the order of 1017-1018/cm3 with low mobility in the range of 0.01-0.1 cm2/V s, a Hall mobility of 8 cm2/V s and a carrier concentration of 5×1014/cm3 have been achieved on a relatively low temperature growth (250 °C) of ZnO. The low carrier concentration indicates that the number of defects have been reduced by a magnitude of nearly a 1000 as compared to the room-temperature annealed growths. Also, it was very clearly seen that for the (002) oriented films of ZnO a high mobility film is achieved.

Enhanced infrared transmission through subwavelength hole arrays in a thin gold film mounted with dielectric micro-domes

NASA Astrophysics Data System (ADS)

Kumar, Raghwendra; Ramakrishna, S. Anantha

2018-04-01

Dielectric micro-domes were mounted on the subwavelength holes of a periodically perforated gold film such that a lens-like micro-dome covers each hole. In comparison to the extraordinary transmission through an array of bare holes in the gold film, this structure showed a further enhanced transmission over a larger range of incident angles with much larger bandwidth at mid-wave infrared wavelengths (3-4.5~μ m). The structure was fabricated using laser interference lithography, a novel back-exposure with an ultra-violet laser, and lift-off process that left behind the micro-domes of SU-8, covering each of the holes in the gold film. The measured transmittance of these perforated gold films, with and without the micro-domes, was verified by electromagnetic wave simulations. The enhanced transmittance arises from the scattered electromagnetic fields of the micro-domes, which couple the incident light efficiently via the scattered near-fields into the waveguide modes of holes in the plasmonic film. The increased transmittance and the highly enhanced and localized near-fields can be used to enhance the photo-response of infrared detectors over relevant bands, for example, the 3-4.5~μ m band that is used for thermal imaging applications.

A comparative study of the TF-Test®, Kato-Katz, Hoffman-Pons-Janer, Willis and Baermann-Moraes coprologic methods for the detection of human parasitosis.

PubMed

Carvalho, Gabriela Lanna Xavier de; Moreira, Luciano Evangelista; Pena, João Luiz; Marinho, Carolina Coimbra; Bahia, Maria Terezinha; Machado-Coelho, George Luiz Lins

2012-02-01

This study compares the diagnostic accuracy of the TF-Test(®) (TFT) for human parasitosis with results obtained using the traditional Kato-Katz (KK), Hoffman-Pons-Janer (HPJ), Willis and Baermann-Moraes (BM) techniques. Overall, four stool samples were taken from each individual; three alternate-day TFT stool samples and another sample that was collected in a universal container. Stool samples were taken from 331 inhabitants of the community of Quilombola Santa Cruz. The gold standard (GS) for protozoa detection was defined as the combined results for TFT, HPJ and Willis coproscopic techniques; for helminth detection, GS was defined as the combined results for all five coproscopic techniques (TFT, KK, HPJ, Willis and BM). The positivity rate of each method was compared using the McNemar test. While the TFT exhibited similar positivity rates to the GS for Entamoeba histolytica/dispar (82.4%) and Giardia duodenalis (90%), HPJ and Willis techniques exhibited significantly lower positivity rates for these protozoa. All tests exhibited significantly lower positivity rates compared with GS for the diagnosis of helminths. The KK technique had the highest positivity rate for diagnosing Schistosoma mansoni (74.6%), while the TFT had the highest positivity rates for Ascaris lumbricoides (58.1%) and hookworm (75%); HPJ technique had the highest positivity rate for Strongyloides stercoralis (50%). Although a combination of tests is the most accurate method for the diagnosis of enteral parasites, the TFT reliably estimates the prevalence of protozoa and selected helminths, such as A. lumbricoides and hookworm. Further studies are needed to evaluate the detection accuracy of the TFT in samples with varying numbers of parasites.

Technological Innovation of Thin-Film Transistors: Technology Development, History, and Future

NASA Astrophysics Data System (ADS)

Yamamoto, Yoshitaka

2012-06-01

The scale of the liquid crystal display industry has expanded rapidly, driven by technological innovations for thin-film transistors (TFTs). The TFT technology, which started from amorphous silicon (a-Si), has produced large TVs, and low-temperature polycrystalline silicon (poly-Si) has become a core technology for small displays, such as mobile phones. Recently, various TFT technological seeds have been realized, indicating that new information appliances that match new lifestyles and information infrastructures will be available in the near future. In this article, I review the history of TFT technology and discuss the future of TFT technological development from the technological innovation viewpoint.

Phased Array Ultrasound: Initial Development of PAUT Inspection of Self-Reacting Friction Stir Welds

NASA Technical Reports Server (NTRS)

Rairigh, Ryan

2008-01-01

This slide presentation reviews the development of Phased Array Ultrasound (PAUT) as a non-destructive examination method for Self Reacting Friction Stir Welds (SR-FSW). PAUT is the only NDE method which has been shown to detect detrimental levels of Residual Oxide Defect (ROD), which can result in significant decrease in weld strength. The presentation reviews the PAUT process, and shows the results in comparison with x-ray radiography.

A Transdermal Drug Delivery System Based on LIGA Technology and Soft Lithography

NASA Astrophysics Data System (ADS)

Matteucci, Marco; Perennes, Frederic; Marmiroli, Benedetta; Di Fabrizio, Enzo

2007-01-01

This report presents a transdermal drug delivery system based on LIGA fabricated microparts. It is a portable device combining a magnetically actuated micro gear pump with a microneedle array. The fluidic behaviour of the system is analyzed in order to predict its performance according to the dimension of the microparts and then compared to experimental data. The manufacturing process of both micropump and microneedle array are described.

Thought Field Therapy: A Former Insider's Experience

ERIC Educational Resources Information Center

Pignotti, Monica

2007-01-01

Thought Field Therapy (TFT) is a novel therapy that employs finger tapping on purported acupressure points. Over the past decade, TFT, promoted on the Internet and through testimonials of fast cures, has gained popularity with therapists, including clinical social workers. Although TFT claims to cure a wide variety of psychological and physical…

Enhancing the color gamut of white displays using novel deep-blue organic fluorescent dyes to form color-changed thin films with improved efficiency

NASA Astrophysics Data System (ADS)

Liu, Wei-Ting; Huang, Wen-Yao

2012-10-01

This study used the novel fluorescence based deep-blue-emitting molecule BPVPDA in an organic fluorescent color thin film to exhibit deep blue color with CIE coordinates of (0.13, 0.16). The developed original organic RGB color thin film technology enables the optimization of the distinctive features of an organic light emitting diode (OLED) and thin-film-transistor (TFT) LCD display. The color filter structure maintains the same high resolution to obtain a higher level of brightness in comparison with conventional organic RGB color thin film. The image-processing engine is designed to achieve a sharp text image for a TFT LCD with organic color thin films. The organic color thin films structure uses an organic dye dopant in a limpid photoresist. With this technology, the following characteristics can be obtained: 1. high color reproduction of gamut ratio, and 2. improved luminous efficiency with organic color fluorescent thin film. This performance is among the best results ever reported for a color-filter used on TFT-LCD or OLED.

Nano-porous electrode systems by colloidal lithography for sensitive electrochemical detection: fabrication technology and properties

NASA Astrophysics Data System (ADS)

Lohmüller, Theobald; Müller, Ulrich; Breisch, Stefanie; Nisch, Wilfried; Rudorf, Ralf; Schuhmann, Wolfgang; Neugebauer, Sebastian; Kaczor, Markus; Linke, Stephan; Lechner, Sebastian; Spatz, Joachim; Stelzle, Martin

2008-11-01

A porous metal-insulator-metal sensor system was developed with the ultimate goal of enhancing the sensitivity of electrochemical sensors by taking advantage of redox cycling of electro active molecules between closely spaced electrodes. The novel fabrication technology is based on thin film deposition in combination with colloidal self-assembly and reactive ion etching to create micro- or nanopores. This cost effective approach is advantageous compared to common interdigitated electrode arrays (IDA) since it does not require high definition lithography technology. Spin-coating and random particle deposition, combined with a new sublimation process are discussed as competing strategies to generate monolayers of colloidal spheres. Metal-insulator-metal layer systems with low leakage currents < 10 pA and an insulator thickness as low as 100 nm were obtained at high yield (typically > 90%). We also discuss possible causes of sensor failure with respect to critical fabrication processes. Short circuits which could occur during or as a result of the pore etching process were investigated in detail. Infrared microscopy in combination with focused ion beam etching/SEM were used to reveal a defect mechanism creating interconnects and increased leakage current between the top and bottom electrodes. Redox cycling provides for amplification factors of >100. A general applicability for electrochemical diagnostic assays is therefore anticipated.

IGZO TFT-based circuit with tunable threshold voltage by laser annealing

NASA Astrophysics Data System (ADS)

Huang, Xiaoming; Yu, Guang; Wu, Chenfei

2017-11-01

In this work, a high-performance inverter based on amorphous indium-gallium-zinc oxide thin-film transistors (TFTs) has been fabricated, which consists of a driver TFT and a load TFT. The threshold voltage (Vth) of the load TFT can be tuned by applying an area-selective laser annealing. The transfer curve of the load TFT shows a parallel shift into the negative bias direction upon laser annealing. Based on x-ray photoelectron spectroscopy analyses, the negative Vth shift can be attributed to the increase of oxygen vacancy concentration within the device channel upon laser irradiation. Compared to the untreated inverter, the laser annealed inverter shows much improved switching characteristics, including a large output swing range which is close to full swing, as well as an enhanced output voltage gain. Furthermore, the dynamic performance of ring oscillator based on the laser-annealed inverter is improved.

Effect of mesa structure formation on the electrical properties of zinc oxide thin film transistors.

PubMed

Singh, Shaivalini; Chakrabarti, P

2014-05-01

ZnO based bottom-gate thin film transistor (TFT) with SiO2 as insulating layer has been fabricated with two different structures. The effect of formation of mesa structure on the electrical characteristics of the TFTs has been studied. The formation of mesa structure of ZnO channel region can definitely result in better control over channel region and enhance value of channel mobility of ZnO TFT. As a result, by fabricating a mesa structured TFT, a better value of mobility and on-state current are achieved at low voltages. A typical saturation current of 1.85 x 10(-7) A under a gate bias of 50 V is obtained for non mesa structure TFT while for mesa structured TFT saturation current of 5 x 10(-5) A can be obtained at comparatively very low gate bias of 6.4 V.

Materials Development for Auxiliary Components for Large Compact Mo/Au TES Arrays

NASA Technical Reports Server (NTRS)

Finkbeiner, F. m.; Chervenak, J. A.; Bandler, S. R.; Brekosky, R.; Brown, A. D.; Figueroa-Feliciano, E.; Iyomoto, N.; Kelley, R. L.; Kilbourne, C. A.; Porter, F. S.;

Improvement of Bone Healing by Neutralization of microRNA-335-5p, but not by Neutralization of microRNA-92A in Bone Marrow Mononuclear Cells Transplanted into a Large Femur Defect of the Rat.

PubMed

Janko, Maren; Dietz, Konstantin; Rachor, Julia; Sahm, Julian; Schroder, Katrin; Schaible, Alexander; Nau, Christoph; Seebach, Caroline; Marzi, Ingo; Henrich, Dirk

2018-04-23

Transplanted bone marrow mononuclear cells (BMC) support the healing of large bone defects. Neutralization of microRNA (MiR) that negatively affects key processes of the reparative response in BMC might help to further improve the beneficial effect of transplanted BMC in bone healing. Hence, the aim of this study was to evaluate if the neutralization of MiR-92A (vascularization) and MiR-335-5p (osteogenic differentiation) in BMC using specific antiMiRs leads to a further improvement of the BMC-supported therapy of large bone defects. BMC transiently transfected with antiMiR- 92A, antiMiR-335, antiMiR-92A, and antiMiR-355 or control antiMiR were seeded on β-TCP (beta-tricalcium phosphate) and placed in a femoral large bone defect (5 mm) in Sprague-Dawley rats. Ultimate load as well as osseous integration of the β-TCP-scaffolds were significantly improved in the antiMiR-335 group compared to the control group after 8 weeks, whereas neutralization of antiMiR-92A lead to an improvement of early vascularization after 1 week, but not to enhanced bone healing after 8 weeks. We demonstrated that the targeted inhibition of MiRs in transplanted BMC is a new approach that enhances BMC-supported bone healing.

Enhancing the color gamut of white displays using novel deep-blue organic fluorescent dyes to form color-changed thin films with improved efficiency

NASA Astrophysics Data System (ADS)

Liu, Wei-ting; Huang, Wen-Yao

2012-06-01

This study used novel fluorescence based deep-blue-emitting molecules, namely BPVPDA, an organic fluorescence color thin film using BPVPDA exhibit deep blue fluorine with CIE coordinates of (0.13,0.16). The developed original Organic RGB color thin film technology enables the optimization of the distinctive features of an organic light emitting diode (OLED) and (TFT) LCD display. The color filter structure maintains the same high resolution to obtain a higher level of brightness, in comparison with conventional organic RGB color thin film. The image-processing engine is designed to achieve a sharp text image for a thin-film-transistor (TFT) LCD with organic color thin films. The organic color thin films structure uses organic dye dopent in limpid photo resist. With this technology , the following characteristics can be obtained: (1) high color reproduction of gamut ratio, and (2) improved luminous efficiency with organic color fluorescence thin film. This performance is among the best results ever reported for a color-filter used on TFT-LCD and OLED.

Evaluation of methanogenic treatment of TMAH (tetra-methyl ammonium hydroxide) in a full-scale TFT-LCD wastewater treatment process.

PubMed

Hu, T H; Whang, L M; Lei, C N; Chen, C F; Chiang, T Y; Lin, L B; Chen, H W; Liu, P W G; Cheng, S S

2010-01-01

This study evaluated TMAH biodegradation under methanogenic conditions. Under methanogenic conditions, a sludge from a full-scale UASB treating TFT-LCD wastewater was able to degrade 2,000 mg/L of TMAH within 10 h and attained a specific degradation rate of 19.2 mgTMAH/gVSS-h. Furthermore, several chemicals including some surfactants, DMSO, and sulfate were examined for their potential inhibitory effects on TMAH biodegradation under methanogenic conditions. The results indicated that surfactant S1 (up to 2%) and DMSO (up to 1,000 mg/L) presented negligible inhibitory effects on TMAH degradation, while surfactant S2 (0.2-1%) might inhibit methanogenic reaction without any TMAH degradation for 3-5 h. At sulfate concentrations higher than 300 mg/L, a complete inhibition of methanogenic reaction and TMAH biodegradation was observed. Results from cloning and sequencing of archaeal 16S rRNA gene fragments showed that Methanosarcina barkeri and Methanosarcina mazei were the dominant methanogens in the UASB treating TMAH-containing TFT-LCD wastewater.

Novel anti-reflection technology for GaAs single-junction solar cells using surface patterning and Au nanoparticles.

PubMed

Kim, Youngjo; Lam, Nguyen Dinh; Kim, Kangho; Kim, Sangin; Rotermund, Fabian; Lim, Hanjo; Lee, Jaejin

2012-07-01

Single-junction GaAs solar cell structures were grown by low-pressure MOCVD on GaAs (100) substrates. Micro-rod arrays with diameters of 2 microm, 5 microm, and 10 microm were fabricated on the surfaces of the GaAs solar cells via photolithography and wet chemical etching. The patterned surfaces were coated with Au nanoparticles using an Au colloidal solution. Characteristics of the GaAs solar cells with and without the micro-rod arrays and Au nanoparticles were investigated. The short-circuit current density of the GaAs solar cell with 2 microm rod arrays and Au nanoparticles increased up to 34.9% compared to that of the reference cell without micro-rod arrays and Au nanoparticles. The conversion efficiency of the GaAs solar cell that was coated with Au nanoparticles on the patterned surface with micro-rod arrays can be improved from 14.1% to 19.9% under 1 sun AM 1.5G illumination. These results show that micro-rod arrays and Au nanoparticle coating can be applied together in surface patterning to achieve a novel cost-effective anti-reflection technology.

The Enhanced Formaldehyde-Sensing Properties of P3HT-ZnO Hybrid Thin Film OTFT Sensor and Further Insight into Its Stability

PubMed Central

Tai, Huiling; Li, Xian; Jiang, Yadong; Xie, Guangzhong; Du, Xiaosong

2015-01-01

A thin-film transistor (TFT) having an organic–inorganic hybrid thin film combines the advantage of TFT sensors and the enhanced sensing performance of hybrid materials. In this work, poly(3-hexylthiophene) (P3HT)-zinc oxide (ZnO) nanoparticles' hybrid thin film was fabricated by a spraying process as the active layer of TFT for the employment of a room temperature operated formaldehyde (HCHO) gas sensor. The effects of ZnO nanoparticles on morphological and compositional features, electronic and HCHO-sensing properties of P3HT-ZnO thin film were systematically investigated. The results showed that P3HT-ZnO hybrid thin film sensor exhibited considerable improvement of sensing response (more than two times) and reversibility compared to the pristine P3HT film sensor. An accumulation p-n heterojunction mechanism model was developed to understand the mechanism of enhanced sensing properties by incorporation of ZnO nanoparticles. X-ray photoelectron spectroscope (XPS) and atomic force microscopy (AFM) characterizations were used to investigate the stability of the sensor in-depth, which reveals the performance deterioration was due to the changes of element composition and the chemical state of hybrid thin film surface induced by light and oxygen. Our study demonstrated that P3HT-ZnO hybrid thin film TFT sensor is beneficial in the advancement of novel room temperature HCHO sensing technology. PMID:25608214

The enhanced formaldehyde-sensing properties of P3HT-ZnO hybrid thin film OTFT sensor and further insight into its stability.

PubMed

Tai, Huiling; Li, Xian; Jiang, Yadong; Xie, Guangzhong; Du, Xiaosong

2015-01-19

A thin-film transistor (TFT) having an organic-inorganic hybrid thin film combines the advantage of TFT sensors and the enhanced sensing performance of hybrid materials. In this work, poly(3-hexylthiophene) (P3HT)-zinc oxide (ZnO) nanoparticles' hybrid thin film was fabricated by a spraying process as the active layer of TFT for the employment of a room temperature operated formaldehyde (HCHO) gas sensor. The effects of ZnO nanoparticles on morphological and compositional features, electronic and HCHO-sensing properties of P3HT-ZnO thin film were systematically investigated. The results showed that P3HT-ZnO hybrid thin film sensor exhibited considerable improvement of sensing response (more than two times) and reversibility compared to the pristine P3HT film sensor. An accumulation p-n heterojunction mechanism model was developed to understand the mechanism of enhanced sensing properties by incorporation of ZnO nanoparticles. X-ray photoelectron spectroscope (XPS) and atomic force microscopy (AFM) characterizations were used to investigate the stability of the sensor in-depth, which reveals the performance deterioration was due to the changes of element composition and the chemical state of hybrid thin film surface induced by light and oxygen. Our study demonstrated that P3HT-ZnO hybrid thin film TFT sensor is beneficial in the advancement of novel room temperature HCHO sensing technology.

Active pixel imagers incorporating pixel-level amplifiers based on polycrystalline-silicon thin-film transistors

PubMed Central

El-Mohri, Youcef; Antonuk, Larry E.; Koniczek, Martin; Zhao, Qihua; Li, Yixin; Street, Robert A.; Lu, Jeng-Ping

2009-01-01

Active matrix, flat-panel imagers (AMFPIs) employing a 2D matrix of a-Si addressing TFTs have become ubiquitous in many x-ray imaging applications due to their numerous advantages. However, under conditions of low exposures and∕or high spatial resolution, their signal-to-noise performance is constrained by the modest system gain relative to the electronic additive noise. In this article, a strategy for overcoming this limitation through the incorporation of in-pixel amplification circuits, referred to as active pixel (AP) architectures, using polycrystalline-silicon (poly-Si) TFTs is reported. Compared to a-Si, poly-Si offers substantially higher mobilities, enabling higher TFT currents and the possibility of sophisticated AP designs based on both n- and p-channel TFTs. Three prototype indirect detection arrays employing poly-Si TFTs and a continuous a-Si photodiode structure were characterized. The prototypes consist of an array (PSI-1) that employs a pixel architecture with a single TFT, as well as two arrays (PSI-2 and PSI-3) that employ AP architectures based on three and five TFTs, respectively. While PSI-1 serves as a reference with a design similar to that of conventional AMFPI arrays, PSI-2 and PSI-3 incorporate additional in-pixel amplification circuitry. Compared to PSI-1, results of x-ray sensitivity demonstrate signal gains of ∼10.7 and 20.9 for PSI-2 and PSI-3, respectively. These values are in reasonable agreement with design expectations, demonstrating that poly-Si AP circuits can be tailored to provide a desired level of signal gain. PSI-2 exhibits the same high levels of charge trapping as those observed for PSI-1 and other conventional arrays employing a continuous photodiode structure. For PSI-3, charge trapping was found to be significantly lower and largely independent of the bias voltage applied across the photodiode. MTF results indicate that the use of a continuous photodiode structure in PSI-1, PSI-2, and PSI-3 results in optical fill factors that are close to unity. In addition, the greater complexity of PSI-2 and PSI-3 pixel circuits, compared to that of PSI-1, has no observable effect on spatial resolution. Both PSI-2 and PSI-3 exhibit high levels of additive noise, resulting in no net improvement in the signal-to-noise performance of these early prototypes compared to conventional AMFPIs. However, faster readout rates, coupled with implementation of multiple sampling protocols allowed by the nondestructive nature of pixel readout, resulted in a significantly lower noise level of ∼560 e (rms) for PSI-3. PMID:19673229

Active pixel imagers incorporating pixel-level amplifiers based on polycrystalline-silicon thin-film transistors.

PubMed

El-Mohri, Youcef; Antonuk, Larry E; Koniczek, Martin; Zhao, Qihua; Li, Yixin; Street, Robert A; Lu, Jeng-Ping

2009-07-01

Active matrix, flat-panel imagers (AMFPIs) employing a 2D matrix of a-Si addressing TFTs have become ubiquitous in many x-ray imaging applications due to their numerous advantages. However, under conditions of low exposures and/or high spatial resolution, their signal-to-noise performance is constrained by the modest system gain relative to the electronic additive noise. In this article, a strategy for overcoming this limitation through the incorporation of in-pixel amplification circuits, referred to as active pixel (AP) architectures, using polycrystalline-silicon (poly-Si) TFTs is reported. Compared to a-Si, poly-Si offers substantially higher mobilities, enabling higher TFT currents and the possibility of sophisticated AP designs based on both n- and p-channel TFTs. Three prototype indirect detection arrays employing poly-Si TFTs and a continuous a-Si photodiode structure were characterized. The prototypes consist of an array (PSI-1) that employs a pixel architecture with a single TFT, as well as two arrays (PSI-2 and PSI-3) that employ AP architectures based on three and five TFTs, respectively. While PSI-1 serves as a reference with a design similar to that of conventional AMFPI arrays, PSI-2 and PSI-3 incorporate additional in-pixel amplification circuitry. Compared to PSI-1, results of x-ray sensitivity demonstrate signal gains of approximately 10.7 and 20.9 for PSI-2 and PSI-3, respectively. These values are in reasonable agreement with design expectations, demonstrating that poly-Si AP circuits can be tailored to provide a desired level of signal gain. PSI-2 exhibits the same high levels of charge trapping as those observed for PSI-1 and other conventional arrays employing a continuous photodiode structure. For PSI-3, charge trapping was found to be significantly lower and largely independent of the bias voltage applied across the photodiode. MTF results indicate that the use of a continuous photodiode structure in PSI-1, PSI-2, and PSI-3 results in optical fill factors that are close to unity. In addition, the greater complexity of PSI-2 and PSI-3 pixel circuits, compared to that of PSI-1, has no observable effect on spatial resolution. Both PSI-2 and PSI-3 exhibit high levels of additive noise, resulting in no net improvement in the signal-to-noise performance of these early prototypes compared to conventional AMFPIs. However, faster readout rates, coupled with implementation of multiple sampling protocols allowed by the nondestructive nature of pixel readout, resulted in a significantly lower noise level of approximately 560 e (rms) for PSI-3.

Solution-processed hybrid organic-inorganic complementary thin-film transistor inverter

NASA Astrophysics Data System (ADS)

Cheong, Heajeong; Kuribara, Kazunori; Ogura, Shintaro; Fukuda, Nobuko; Yoshida, Manabu; Ushijima, Hirobumi; Uemura, Sei

2016-04-01

We investigated hybrid organic-inorganic complementary inverters with a solution-processed indium-gallium-zinc-oxide (IGZO) n-channel thin-film transistor (TFT) and p-channel TFTs using the high-uniformity polymer poly[2,5-bis(alkyl)pyrrolo[3,4-c]pyrrolo-1,4(2H,5H)-dione-alt-5,5-di(thiophene-2-yl)-2,2-(E)-2-(2-(thiophen-2-yl)vinyl)thiophene] (PDVT-10). The IGZO TFT was fabricated at 150 °C for 1 min. It showed a high field-effect mobility of 0.9 cm2·V-1·s-1 and a high on/off current ratio of 107. A hybrid complementary inverter was fabricated by combining IGZO with a PDVT-10 thin-film transistor and its operation was confirmed.

Processing soft materials for integrated photonic and macroelectronic components and devices

NASA Astrophysics Data System (ADS)

Tsay, Candice Ruth

Incorporating soft materials into micro-fabrication processes opens up new functionalities for fabricated devices, but requires unique processing routes. This thesis presents our development of integrated photonic and macroelectronic structures through processing innovations that unite disparate inorganic/organic, and soft/rigid materials systems. For the integrated photonic system, we focus our efforts on chalcogenide glasses, dielectric materials that exhibit a variety of optical properties that make them desirable for near- and mid-infrared communications and sensing applications. However, processing limitations for these relatively fragile materials have made the direct integration of waveguides with sources or detectors challenging. Here we demonstrate the viability of several additive methods for patterning chalcogenide glass waveguides from solution. In particular, we focus on two complementary soft lithography methods. The first, micro-molding in capillaries (MIMIC), is shown to fabricate multi-mode As2S 3 waveguides which are directly integrated with quantum cascade lasers (QCLs). In a second method, we demonstrate the ability of micro-transfer molding (muTM), to produce arrays of single mode rib waveguides over large areas while maintaining low surface and edge roughness. These methods form a suite of processes that can be applied to chalcogenide solutions to create a diverse array of mid-IR photonic structures ranging from less than 5 to 10's of mum in cross-sectional dimension. Optical characterization, including measurement of waveguide loss by cut-back, is carried out in the mid-IR using QCLs. In addition, materials characterization of the chalcogenide glass structures is carried out to determine loss mechanisms and optimize processing. While we use soft polymeric materials as molds to pattern chalcogenide glasses, we also employ them as substrate material for stretchable electronic systems, which comprise a new class of flexible macroelectronics. These devices must undergo elastic deformation to large strain (>10%), for applications in which electronics are conformally shaped around surfaces of arbitrary shape, like many biological surfaces. We develop strategies for processing stretchable metallic electrodes and study the mechanism of their stretchability via careful observation of thin film micro-structures. Our macroelectronic work culminates in fabrication of stretchable microelectrode arrays that interface with brain tissue, laying the groundwork for future development of advanced bio-electronic interfaces.

High-Performance Flexible Force and Temperature Sensing Array with a Robust Structure

NASA Astrophysics Data System (ADS)

Kim, Min-Seok; Song, Han-Wook; Park, Yon-Kyu

We have developed a flexible tactile sensor array capable of sensing physical quantities, e.g. force and temperature with high-performances and high spatial resolution. The fabricated tactile sensor consists of 8 × 8 force measuring array with 1 mm spacing and a thin metal (copper) temperature sensor. The flexible force sensing array consists of sub-millimetre-size bar-shaped semi-conductor strain gage array attached to a thin and flexible printed circuit board covered by stretchable elastomeric material on both sides. This design incorporates benefits of both materials; the semi-conductor's high performance and the polymer's mechanical flexibility and robustness, while overcoming their drawbacks of those two materials. Special fabrication processes, so called “dry-transfer technique” have been used to fabricate the tactile sensor along with standard micro-fabrication processes.

Micro-CT evaluation of bone defects: applications to osteolytic bone metastases, bone cysts, and fracture.

PubMed

Buie, Helen R; Bosma, Nick A; Downey, Charlene M; Jirik, Frank R; Boyd, Steven K

2013-11-01

Bone defects can occur in various forms and present challenges to performing a standard micro-CT evaluation of bone quality because most measures are suited to homogeneous structures rather than ones with spatially focal abnormalities. Such defects are commonly associated with pain and fragility. Research involving bone defects requires quantitative approaches to be developed if micro-CT is to be employed. In this study, we demonstrate that measures of inter-microarchitectural bone spacing are sensitive to the presence of focal defects in the proximal tibia of two distinctly different mouse models: a burr-hole model for fracture healing research, and a model of osteolytic bone metastases. In these models, the cortical and trabecular bone compartments were both affected by the defect and were, therefore, evaluated as a single unit to avoid splitting the defects into multiple analysis regions. The burr-hole defect increased mean spacing (Sp) by 27.6%, spacing standard deviation (SpSD) by 113%, and maximum spacing (Spmax) by 72.8%. Regression modeling revealed SpSD (β=0.974, p<0.0001) to be a significant predictor of the defect volume (R(2)=0.949) and Spmax (β=0.712, p<0.0001) and SpSD (β=0.271, p=0.022) to be significant predictors of the defect diameter (R(2)=0.954). In the mice with osteolytic bone metastases, spacing parameters followed similar patterns of change as reflected by other imaging technologies, specifically bioluminescence data which is indicative of tumor burden. These data highlight the sensitivity of spacing measurements to bone architectural abnormalities from 3D micro-CT data and provide a tool for quantitative evaluation of defects within a bone. Copyright © 2013 IPEM. Published by Elsevier Ltd. All rights reserved.

Immobilizing enzymes onto electrode arrays by hydrogel photolithography to fabricate multi-analyte electrochemical biosensors.

PubMed

Yan, Jun; Pedrosa, Valber A; Simonian, Aleksandr L; Revzin, Alexander

2010-03-01

This paper describes a biomaterial microfabrication approach for interfacing functional biomolecules (enzymes) with electrode arrays. Poly (ethylene glycol) (PEG) hydrogel photopatterning was employed to integrate gold electrode arrays with the enzymes glucose oxidase (GOX) and lactate oxidase (LOX). In this process, PEG diacrylate (DA)-based prepolymer containing enzyme molecules as well as redox species (vinylferrocene) was spin-coated, registered, and UV cross-linked on top of an array of gold electrodes. As a result, enzyme-carrying circular hydrogel structures (600 microm diameter) were fabricated on top of 300 microm diameter gold electrodes. Importantly, when used with multiple masks, hydrogel photolithography allowed us to immobilize GOX and LOX molecules on adjacent electrodes within the same electrode array. Cyclic voltammetry and amperometry were used to characterize biosensor electrode arrays. The response of the biosensor array was linear for up to 20 mM glucose with sensitivity of 0.9 microA cm(-2) mM(-1) and 10 mM lactate with sensitivity of 1.1 microA cm(-2) mM(-1). Importantly, simultaneous detection of glucose and lactate from the same electrode array was demonstrated. A novel strategy for integrating biological and electrical components of a biosensor described in this paper provides the flexibility to spatially resolve and register different biorecognition elements with individual members of a miniature electrode array. Of particular interest to us are future applications of these miniature electrodes for real-time monitoring of metabolite fluxes in the vicinity of living cells.

SU34. A Systematic Review of Behavioral Research and Lesion Evidence for the 2-Factor Theory of Monothematic Delusions

PubMed Central

Neustadter, Eli; Pinder, Juno; Corlett, Philip

2017-01-01

Abstract Background: Two-factor theory (TFT) posits monothematic delusion formation requires damage producing delusion content (factor 1) and a deficit in belief evaluation (factor 2, posited to be localized in right frontal cortex). The purpose of the current study was 2-fold: (1) to review the behavioral data supporting TFT and (2) to assess whether locations of delusion-inducing lesions were consistent with TFT predictions: ie, common factor 1 damage within a particular monothematic delusion and common factor 2 damage across delusions. Furthermore, factor 2 damage ought to distinguish Capgras syndrome (the delusion that a previously familiar person is an imposter) from nondelusional-affective agnosia (unfamiliarity without delusion). Methods: We reviewed all papers concerned with TFT and all studies of galvanic skin response (GSR) in monothematic delusions (frequently cited as behavioral evidence for TFT). Next, we reviewed case reports of lesion-induced monothematic delusions including Capgras, Fregoli, Cotard, and somatoparaphrenia, as well as affective agnosia. We report lesion location frequencies in 12 regions of interest. Results: We found 27 articles on TFT. Only 3 contained empirical evidence (11%, all hypnosis studies): one had no direct hypothesis regarding TFT, one was inconclusive, and another failed to support TFT. We found 7 additional GSR studies of Capgras, 6 of which reported statistically significant abnormal GSR, but no effects were specific to the familiar person accused of being an imposter. One neuroimaging case study of Capgras did find fMRI correlates of perceiving the imposter in the left hemisphere. One study of somatoparaphrenia reported a GSR deficit to noxious stimuli approaching the denied limb. There were no published studies testing TFT predictions about Cotard or Fregoli. We analyzed 46 reports of lesion-induced delusions and 20 cases of affective agnosia. Right hemisphere damage was most common in monothematic delusion cases (χ2(1, N = 46) = 40.09, P < .0001). Within the right hemisphere, frontal and temporal damage were most common (46% of cases had damage in these regions). The patterns of regional codamage were not consistent within delusion contents (as factor 1 would demand). Contrary to TFT, affective agnosia was associated with bilateral frontal damage more frequently than Capgras delusion (P < .005), which calls into question a right frontal locus for factor 2. Conclusion: Overall, this study found no strong hypothesis-driven support of TFT. GSR findings often failed to account for the specificity of delusional content and no common pattern of brain damage for factor 2 emerged. However, the anatomical analysis was coarse (by dint of the data available in the case reports), and diaschesis effects (wherein damage in one region effects function of a distant region) are also potentially important.

Morphologies and optical and electrical properties of InGaN/GaN micro-square array light-emitting diode chips.

PubMed

Han, Dan; Ma, Shufang; Jia, Zhigang; Liu, Peizhi; Jia, Wei; Shang, Lin; Zhai, Guangmei; Xu, Bingshe

2018-04-10

InGaN/GaN micro-square array light-emitting diode (LED) chips (micro-chips) have been prepared via the focused ion beam (FIB) etching technique, which can not only reduce ohmic contact degradation but also control the aspect ratio precisely in three-dimensional (3D) structure LED (3D-LED) device fabrication. The effects of FIB beam current and micro-square array depth on morphologies and optical and electrical properties of the micro-chips have been studied. Our results show that sidewall surface morphology and optical and electrical properties of the micro-chips degrade with increased beam current. After potassium hydroxide etching with different times, an optimal current-voltage and luminescence performance can be obtained. Combining the results of cathodoluminescence mappings and light output-current characteristics, the light extraction efficiency of the micro-chips is reduced as FIB etch depth increases. The mechanisms of micro-square depth on light extraction have been revealed by 3D finite difference time domain.

Flexible piezoelectric nanogenerators based on a transferred ZnO nanorod/Si micro-pillar array

NASA Astrophysics Data System (ADS)

Baek, Seong-Ho; Park, Il-Kyu

2017-03-01

Flexible piezoelectric nanogenerators (PNGs) based on a composite of ZnO nanorods (NRs) and an array of Si micro-pillars (MPs) are demonstrated by a transfer process. The flexible composite structure was fabricated by hydrothermal growth of ZnO NRs on an electrochemically etched Si MP array with various lengths followed by mechanically delaminating the Si MP arrays from the Si substrate after embedding them in a polydimethylsiloxane matrix. Because the Si MP arrays act as a supporter to connect the ZnO NRs electrically and mechanically, verified by capacitance measurement, the output voltage from the flexible PNGs increased systematically with the increased density ZnO NRs depending on the length of the Si MPs. The flexible PNGs showed 3.2 times higher output voltage with a small change in current with increasing Si MP length from 5 to 20 μm. The enhancement of the output voltage is due to the increased number of series-connected ZnO NRs and the beneficial effect of a ZnO NR/Si MP heterojunction on reducing free charge screening effects. The flexible PNGs can be attached on fingers as a wearable electrical power source or motion sensor.

In-vivo quantification of primary microRNA processing by Drosha with a luciferase based system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allegra, Danilo; Cooperation Unit 'Mechanisms of Leukemogenesis', B061, DKFZ, Im Neuenheimer Feld 280, 69120 Heidelberg; Mertens, Daniel, E-mail: daniel.mertens@uniklinik-ulm.de

2011-03-25

Research highlights: {yields} Posttranscriptional regulation of miRNA processing is difficult to quantify. {yields} Our in-vivo processing assay can quantify Drosha cleavage in live cells. {yields} It is based on luciferase reporters fused with pri-miRNAs. {yields} The assay validates the processing defect caused by a mutation in pri-16-1. {yields} It is a sensitive method to quantify pri-miRNA cleavage by Drosha in live cells. -- Abstract: The RNAse III Drosha is responsible for the first step of microRNA maturation, the cleavage of primary miRNA to produce the precursor miRNA. Processing by Drosha is finely regulated and influences the amount of mature microRNAmore » in a cell. We describe in the present work a method to quantify Drosha processing activity in-vivo, which is applicable to any microRNA. With respect to other methods for measuring Drosha activity, our system is faster and scalable, can be used with any cellular system and does not require cell sorting or use of radioactive isotopes. This system is useful to study regulation of Drosha activity in physiological and pathological conditions.« less

Cortical bone thickening in Type A posterior atlas arch defects: experimental report.

PubMed

Sanchis-Gimeno, Juan A; Llido, Susanna; Guede, David; Martinez-Soriano, Francisco; Ramon Caeiro, Jose; Blanco-Perez, Esther

2017-03-01

To date, no information about the cortical bone microstructural properties in atlas vertebrae with posterior arch defects has been reported. To test if there is an increased cortical bone thickening in atlases with Type A posterior atlas arch defects in an experimental model. Micro-computed tomography (CT) study on cadaveric atlas vertebrae. We analyzed the cortical bone thickness, the cortical volume, and the medullary volume (SkyScan 1172 Bruker micro-CT NV, Kontich, Belgium) in cadaveric dry vertebrae with a Type A atlas arch defect and normal control vertebrae. The micro-CT study revealed significant differences in cortical bone thickness (p=.005), cortical volume (p=.003), and medullary volume (p=.009) values between the normal and the Type A vertebrae. Type A congenital atlas arch defects present a cortical bone thickening that may play a protective role against atlas fractures. Copyright © 2016 Elsevier Inc. All rights reserved.

Synthesis and characterization of beta-Ga2O3 nanorod array clumps by chemical vapor deposition.

PubMed

Shi, Feng; Wei, Xiaofeng

2012-11-01

beta-Ga2O3 nanorod array clumps were successfully synthesized on Si (111) substrates by chemical vapor deposition. The composition, microstructure, morphology, and light-emitting property of these clumps were characterized by X-ray diffraction, Fourier transform infrared spectrophotometry, X-ray photoelectron spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy, Raman spectroscopy, and photoluminescence. The results demonstrate that the sample synthesized at 1050 degrees C for 15 min was composed of monoclinic beta-Ga2O3 nanorod array clumps, where each single nanorod was about 300 nm in diameter with some nano-droplets on its tip. These results reveal that the growth mechanism agrees with the vapor-liquid-solid (VLS) process. The photoluminescence spectrum shows that the Ga2O3 nanorods have a blue emission at 438 nm, which may be attributed to defects, such as oxygen vacancies and gallium-oxygen vacancy pairs. Defect-energy aggregation confinement growth theory was proposed to explain the growth mechanism of Ga2O3 nanorod array clumps collaborated with the VLS mechanism.

Llamas: Large-area microphone arrays and sensing systems

NASA Astrophysics Data System (ADS)

Sanz-Robinson, Josue

Large-area electronics (LAE) provides a platform to build sensing systems, based on distributing large numbers of densely spaced sensors over a physically-expansive space. Due to their flexible, "wallpaper-like" form factor, these systems can be seamlessly deployed in everyday spaces. They go beyond just supplying sensor readings, but rather they aim to transform the wealth of data from these sensors into actionable inferences about our physical environment. This requires vertically integrated systems that span the entirety of the signal processing chain, including transducers and devices, circuits, and signal processing algorithms. To this end we develop hybrid LAE / CMOS systems, which exploit the complementary strengths of LAE, enabling spatially distributed sensors, and CMOS ICs, providing computational capacity for signal processing. To explore the development of hybrid sensing systems, based on vertical integration across the signal processing chain, we focus on two main drivers: (1) thin-film diodes, and (2) microphone arrays for blind source separation: 1) Thin-film diodes are a key building block for many applications, such as RFID tags or power transfer over non-contact inductive links, which require rectifiers for AC-to-DC conversion. We developed hybrid amorphous / nanocrystalline silicon diodes, which are fabricated at low temperatures (<200 °C) to be compatible with processing on plastic, and have high current densities (5 A/cm2 at 1 V) and high frequency operation (cutoff frequency of 110 MHz). 2) We designed a system for separating the voices of multiple simultaneous speakers, which can ultimately be fed to a voice-command recognition engine for controlling electronic systems. On a device level, we developed flexible PVDF microphones, which were used to create a large-area microphone array. On a circuit level we developed localized a-Si TFT amplifiers, and a custom CMOS IC, for system control, sensor readout and digitization. On a signal processing level we developed an algorithm for blind source separation in a real, reverberant room, based on beamforming and binary masking. It requires no knowledge about the location of the speakers or microphones. Instead, it uses cluster analysis techniques to determine the time delays for beamforming; thus, adapting to the unique acoustic environment of the room.

Micro hot embossing for high-aspect-ratio structure with materials flow enhancement by polymer sheet

NASA Astrophysics Data System (ADS)

Murakoshi, Yoichi; Shan, Xue-Chuan; Sano, Toshio; Takahashi, Masaharu; Maeda, Ryutaro

2004-04-01

Nano imprinting or Nano embossing process have been introduced to fabricate semiconductor, optical device and Micro Electro Mechanical Systems (MEMS) and the Nano Electro Mechanical Systems (NEMS) to reduce the fabrication cost. In our previous paper, micro hot embossing of Polycarbonate (PC) and Polyetheretherketone (PEEK) for optical switch with 8x8 mirrors was reported. The PC and PEEK sheets were embossed at elevated temperature with an embossing machine designed for the MEMS. In the application, the mirrors on the optical switch had some defects, such as slump, sticking and step at side of the mirror, due to embossing process and process conditions. These defects are attributed to the poor materials flow of plastics into the e Ni mold cavity of complicate shape with different aspect ratio. Therefore, the micro hot embossing is optimized in this paper with PTFE sheet to enhance the materials flow. In this paper, the PC and the PEEK sheets, thickness of 300um, are embossed at elevated temperature with the hot embossing machine with a Nickel mold. To control material flow of the PC or the PEEK sheets, Polytetrafluoroethylene (PTFE) sheet, the thickness of 100um, is placed on the PC or the PEEK sheets at elevated temperature. Mirror shape was transferred with better fidelity on the PC and PEEK sheet, and the thickness of cantilever became thinner than previous embossed structure without the PTFE. Especially, the mirror height and the thickness of cantilever on the PC have been improved at lower embossing temperature.

Tear film thickness after treatment with artificial tears in patients with moderate dry eye disease.

PubMed

Schmidl, Doreen; Schmetterer, Leopold; Witkowska, Katarzyna J; Unterhuber, Angelika; dos Santos, Valentin Aranha; Kaya, Semira; Nepp, Johannes; Baar, Carina; Rosner, Peter; Werkmeister, René M; Garhofer, Gerhard

2015-04-01

This study was designed to investigate the effect of a single-drop instillation of different lacrimal substitutes on tear film thickness (TFT) assessed with optical coherence tomography in patients with mild to moderate dry eye disease. The study was performed in a randomized, double-masked, controlled parallel group design. Patients received a single dose of either unpreserved trehalose 30 mg/mL and sodium hyaluronate 1.5 mg/mL (TH-SH, Thealoz Duo), unpreserved sodium hyaluronate, 0.15% (HA, Hyabak) or sodium chloride, 0.9% (NaCl, Hydrabak) eye drops. Sixty patients finished the study according to the protocol. TFT was measured with a custom-built ultrahigh-resolution Fourier domain optical coherence tomography system providing a resolution of 1.2 μm. The mean TFT before treatment was 2.5 ± 0.4 μm. Ten minutes after instillation, TFT significantly increased in the TH-SH group from 2.4 ± 0.4 to 3.1 ± 0.9 μm (P < 0.01) and in the HA group from 2.4 ± 0.3 to 2.9 ± 0.5 μm (P < 0.01), whereas no significant change was observed in the NaCl group (from 2.6 ± 0.4 to 2.7 ± 0.4 μm, P = 0.76). The increase in TFT remained statistically significant up to 240 minutes after administration of TH-SH. In contrast, the increase in TFT after administration of HA was only statistically significant at 10, 20, and 40 minutes after drop instillation. The findings of this study indicate that single instillation of TH-SH and HA eye drops increases TFT in patients with dry eye disease. The data also indicate longer corneal residence of the TH-containing eye drops. The effect of multiple instillation and long-term use of artificial tears on TFT warrants further investigation.

Micro-array versus nano-array platforms: a comparative study for ODN detection based on SPR enhanced ellipsometry

NASA Astrophysics Data System (ADS)

Celen, Burcu; Demirel, Gökhan; Piskin, Erhan

2011-04-01

The rapid and sensitive detection of DNA has recently attracted worldwide attention for a variety of disease diagnoses and detection of harmful bacteria in food and drink. In this paper, we carried out a comparative study based on surface plasmon resonance enhanced ellipsometry (SPREE) for the detection of oligodeoxynucleotides (ODNs) using micro- and nano-array platforms. The micro-arrayed surfaces were fabricated by a photolithography approach using different types of mask having varying size and shape. Well-ordered arrays of high aspect ratio polymeric nanotubes were also obtained using high molecular weight polystyrene (PS) and anodic aluminum oxide (AAO) membranes having 200 nm pore diameters. The SPREE sensors were then prepared by direct coupling of thiolated probe-ODNs, which contain suitable spacer arms, on gold-coated micro- and nano-arrayed surfaces. We experimentally demonstrated that, for the first time, gold-coated free standing polymeric nano-arrayed platforms can easily be produced and lead to a significant sensor sensitivity gain compared to that of the conventional SPREE surfaces of about four times. We believe that such an enhancement in sensor response could be useful for next generation sensor systems.

Fabrication of amorphous InGaZnO thin-film transistor-driven flexible thermal and pressure sensors

NASA Astrophysics Data System (ADS)

Park, Ick-Joon; Jeong, Chan-Yong; Cho, In-Tak; Lee, Jong-Ho; Cho, Eou-Sik; Kwon, Sang Jik; Kim, Bosul; Cheong, Woo-Seok; Song, Sang-Hun; Kwon, Hyuck-In

2012-10-01

In this work, we present the results concerning the use of amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistor (TFT) as a driving transistor of the flexible thermal and pressure sensors which are applicable to artificial skin systems. Although the a-IGZO TFT has been attracting much attention as a driving transistor of the next-generation flat panel displays, no study has been performed about the application of this new device to the driving transistor of the flexible sensors yet. The proposed thermal sensor pixel is composed of the series-connected a-IGZO TFT and ZnO-based thermistor fabricated on a polished metal foil, and the ZnO-based thermistor is replaced by the pressure sensitive rubber in the pressure sensor pixel. In both sensor pixels, the a-IGZO TFT acts as the driving transistor and the temperature/pressure-dependent resistance of the ZnO-based thermistor/pressure-sensitive rubber mainly determines the magnitude of the output currents. The fabricated a-IGZO TFT-driven flexible thermal sensor shows around a seven times increase in the output current as the temperature increases from 20 °C to 100 °C, and the a-IGZO TFT-driven flexible pressure sensors also exhibit high sensitivity under various pressure environments.

LCD real-time mask technique for fabrication of arbitrarily shaped microstructure

NASA Astrophysics Data System (ADS)

Peng, Qinjun; Guo, Yongkang; Chen, Bo; Du, Jinglei; Xiang, Jinshan; Cui, Zheng

2002-04-01

A new technique to fabricate arbitrarily shaped microstructures by using LCD (liquid crystal display) real- time mask is reported in this paper. Its principle and design method are explained. Based on partial coherent imaging theory, the process to fabricate micro-axicon array and zigzag grating has been simulated. The experiment using a color LCD as real-time mask has been set up. Micro-axicon array and zigzag grating has been fabricated by the LCD real-time mask technique. The 3D surface relief structures were made on pan chromatic silver-halide sensitized gelatin (Kodak-131) with trypsinase etching. The pitch size of zigzag grating is 46.26micrometers . The caliber of axicon is 118.7micrometers , and the etching depth is 1.332micrometers .

Cellularizing hydrogel-based scaffolds to repair bone tissue: How to create a physiologically relevant micro-environment?

PubMed Central

Maisani, Mathieu; Pezzoli, Daniele; Chassande, Olivier; Mantovani, Diego

2017-01-01

Tissue engineering is a promising alternative to autografts or allografts for the regeneration of large bone defects. Cell-free biomaterials with different degrees of sophistication can be used for several therapeutic indications, to stimulate bone repair by the host tissue. However, when osteoprogenitors are not available in the damaged tissue, exogenous cells with an osteoblast differentiation potential must be provided. These cells should have the capacity to colonize the defect and to participate in the building of new bone tissue. To achieve this goal, cells must survive, remain in the defect site, eventually proliferate, and differentiate into mature osteoblasts. A critical issue for these engrafted cells is to be fed by oxygen and nutrients: the transient absence of a vascular network upon implantation is a major challenge for cells to survive in the site of implantation, and different strategies can be followed to promote cell survival under poor oxygen and nutrient supply and to promote rapid vascularization of the defect area. These strategies involve the use of scaffolds designed to create the appropriate micro-environment for cells to survive, proliferate, and differentiate in vitro and in vivo. Hydrogels are an eclectic class of materials that can be easily cellularized and provide effective, minimally invasive approaches to fill bone defects and favor bone tissue regeneration. Furthermore, by playing on their composition and processing, it is possible to obtain biocompatible systems with adequate chemical, biological, and mechanical properties. However, only a good combination of scaffold and cells, possibly with the aid of incorporated growth factors, can lead to successful results in bone regeneration. This review presents the strategies used to design cellularized hydrogel-based systems for bone regeneration, identifying the key parameters of the many different micro-environments created within hydrogels. PMID:28634532

After-effects of TFT-LCD display polarity and display colour on the detection of low-contrast objects.

PubMed

Mayr, Susanne; Buchner, Axel

2010-07-01

Participants performed a word-non-word discrimination task within a car control display emulated on a thin film transistor liquid-crystal display (TFT-LCD). The task simulated an information read-out from a TFT-LCD-based instrument panel. Subsequently, participants performed a low-contrast object detection task that simulated the detection of objects during night-time driving. In experiment 1, words/non-words were presented black-on-white (positive polarity) or white-on-black (negative polarity). In experiments 2 and 3, display colour was additionally manipulated. A positive polarity advantage in the discrimination task was consistently observed. In contrast, positive displays interfered more than negative displays with subsequent detection. The detrimental after-effect of positive polarity displays was strong with white and blue, reduced with amber and absent with red displays. Subjective measures showed a preference for blue over red, but a slight advantage for amber over blue. Implications for TFT-LCD design are derived from the results. STATEMENT OF RELEVANCE: When using TFT-LCDs as car instrument panels, positive polarity red TFT-LCDs are very likely to lead to good instrument readability while at the same time minimising - relative to other colours - the negative effects of an illuminated display on low-contrast object detection during night-time driving.

Life on magnets: stem cell networking on micro-magnet arrays.

PubMed

Zablotskii, Vitalii; Dejneka, Alexandr; Kubinová, Šárka; Le-Roy, Damien; Dumas-Bouchiat, Frédéric; Givord, Dominique; Dempsey, Nora M; Syková, Eva

2013-01-01

Interactions between a micro-magnet array and living cells may guide the establishment of cell networks due to the cellular response to a magnetic field. To manipulate mesenchymal stem cells free of magnetic nanoparticles by a high magnetic field gradient, we used high quality micro-patterned NdFeB films around which the stray field's value and direction drastically change across the cell body. Such micro-magnet arrays coated with parylene produce high magnetic field gradients that affect the cells in two main ways: i) causing cell migration and adherence to a covered magnetic surface and ii) elongating the cells in the directions parallel to the edges of the micro-magnet. To explain these effects, three putative mechanisms that incorporate both physical and biological factors influencing the cells are suggested. It is shown that the static high magnetic field gradient generated by the micro-magnet arrays are capable of assisting cell migration to those areas with the strongest magnetic field gradient, thereby allowing the build up of tunable interconnected stem cell networks, which is an elegant route for tissue engineering and regenerative medicine.

Life on Magnets: Stem Cell Networking on Micro-Magnet Arrays

PubMed Central

Zablotskii, Vitalii; Dejneka, Alexandr; Kubinová, Šárka; Le-Roy, Damien; Dumas-Bouchiat, Frédéric; Givord, Dominique; Dempsey, Nora M.; Syková, Eva

2013-01-01

Interactions between a micro-magnet array and living cells may guide the establishment of cell networks due to the cellular response to a magnetic field. To manipulate mesenchymal stem cells free of magnetic nanoparticles by a high magnetic field gradient, we used high quality micro-patterned NdFeB films around which the stray field’s value and direction drastically change across the cell body. Such micro-magnet arrays coated with parylene produce high magnetic field gradients that affect the cells in two main ways: i) causing cell migration and adherence to a covered magnetic surface and ii) elongating the cells in the directions parallel to the edges of the micro-magnet. To explain these effects, three putative mechanisms that incorporate both physical and biological factors influencing the cells are suggested. It is shown that the static high magnetic field gradient generated by the micro-magnet arrays are capable of assisting cell migration to those areas with the strongest magnetic field gradient, thereby allowing the build up of tunable interconnected stem cell networks, which is an elegant route for tissue engineering and regenerative medicine. PMID:23936425

Experimental study of micro dimple fabrication based on laser shock processing

NASA Astrophysics Data System (ADS)

Li, Kangmei; Hu, Yongxiang; Yao, Zhenqiang

2013-06-01

Micro-dimple array has been generally considered as a valuable texture for sliding surfaces. It can improve lubrication and reduce wear by acting as reservoirs of lubricants and grinding debris. Laser shock processing (LSP) is an innovative process which can not only improve fatigue, corrosion and wearing resistance but also shape metallic parts accurately. In this study, a new process for the fabrication of micro dimples based on LSP was proposed, which was named as laser peen texturing (LPT). Experiments were performed on 2024 aluminum alloy, Oxygen-Free High Conductivity (OFHC) copper and SUS304 stainless steel to study the effects of processing parameters of LPT on surface integrity of the specimen. Surface morphology, micro hardness and microstructure of the micro dimples were investigated under various laser power densities, laser spot diameters and repeated shock numbers. It was found that the depth of the micro dimples induced by LPT is strongly dependent on material properties. The diameter, depth as well as aspect ratio of micro dimples were increased with the laser power density and the repeated shock number under the conditions in this study. But when the laser spot diameter changed, the variation laws of the diameter, depth and aspect ratio of the dimple were different from each other. The results of micro hardness measurements suggested that LPT is beneficial for the improvement of the micro hardness beneath the dimple. Grain refinement was found significantly on 2024 aluminum alloy and OFHC copper but not clearly on SUS304 stainless steel. Both the hardening effect and the grain refinement have close relationship with the depth of the micro dimple.

MECHANISMS IN ENDOCRINOLOGY: Novel genetic causes of short stature.

PubMed

Wit, Jan M; Oostdijk, Wilma; Losekoot, Monique; van Duyvenvoorde, Hermine A; Ruivenkamp, Claudia A L; Kant, Sarina G

2016-04-01

The fast technological development, particularly single nucleotide polymorphism array, array-comparative genomic hybridization, and whole exome sequencing, has led to the discovery of many novel genetic causes of growth failure. In this review we discuss a selection of these, according to a diagnostic classification centred on the epiphyseal growth plate. We successively discuss disorders in hormone signalling, paracrine factors, matrix molecules, intracellular pathways, and fundamental cellular processes, followed by chromosomal aberrations including copy number variants (CNVs) and imprinting disorders associated with short stature. Many novel causes of GH deficiency (GHD) as part of combined pituitary hormone deficiency have been uncovered. The most frequent genetic causes of isolated GHD are GH1 and GHRHR defects, but several novel causes have recently been found, such as GHSR, RNPC3, and IFT172 mutations. Besides well-defined causes of GH insensitivity (GHR, STAT5B, IGFALS, IGF1 defects), disorders of NFκB signalling, STAT3 and IGF2 have recently been discovered. Heterozygous IGF1R defects are a relatively frequent cause of prenatal and postnatal growth retardation. TRHA mutations cause a syndromic form of short stature with elevated T3/T4 ratio. Disorders of signalling of various paracrine factors (FGFs, BMPs, WNTs, PTHrP/IHH, and CNP/NPR2) or genetic defects affecting cartilage extracellular matrix usually cause disproportionate short stature. Heterozygous NPR2 or SHOX defects may be found in ∼3% of short children, and also rasopathies (e.g., Noonan syndrome) can be found in children without clear syndromic appearance. Numerous other syndromes associated with short stature are caused by genetic defects in fundamental cellular processes, chromosomal abnormalities, CNVs, and imprinting disorders. © 2016 European Society of Endocrinology.

A CMOS Time-Resolved Fluorescence Lifetime Analysis Micro-System

PubMed Central

Rae, Bruce R.; Muir, Keith R.; Gong, Zheng; McKendry, Jonathan; Girkin, John M.; Gu, Erdan; Renshaw, David; Dawson, Martin D.; Henderson, Robert K.

2009-01-01

We describe a CMOS-based micro-system for time-resolved fluorescence lifetime analysis. It comprises a 16 × 4 array of single-photon avalanche diodes (SPADs) fabricated in 0.35 μm high-voltage CMOS technology with in-pixel time-gated photon counting circuitry and a second device incorporating an 8 × 8 AlInGaN blue micro-pixellated light-emitting diode (micro-LED) array bump-bonded to an equivalent array of LED drivers realized in a standard low-voltage 0.35 μm CMOS technology, capable of producing excitation pulses with a width of 777 ps (FWHM). This system replaces instrumentation based on lasers, photomultiplier tubes, bulk optics and discrete electronics with a PC-based micro-system. Demonstrator lifetime measurements of colloidal quantum dot and Rhodamine samples are presented. PMID:22291564

MicroRNA array normalization: an evaluation using a randomized dataset as the benchmark.

PubMed

Qin, Li-Xuan; Zhou, Qin

2014-01-01

MicroRNA arrays possess a number of unique data features that challenge the assumption key to many normalization methods. We assessed the performance of existing normalization methods using two microRNA array datasets derived from the same set of tumor samples: one dataset was generated using a blocked randomization design when assigning arrays to samples and hence was free of confounding array effects; the second dataset was generated without blocking or randomization and exhibited array effects. The randomized dataset was assessed for differential expression between two tumor groups and treated as the benchmark. The non-randomized dataset was assessed for differential expression after normalization and compared against the benchmark. Normalization improved the true positive rate significantly in the non-randomized data but still possessed a false discovery rate as high as 50%. Adding a batch adjustment step before normalization further reduced the number of false positive markers while maintaining a similar number of true positive markers, which resulted in a false discovery rate of 32% to 48%, depending on the specific normalization method. We concluded the paper with some insights on possible causes of false discoveries to shed light on how to improve normalization for microRNA arrays.

MicroRNA Array Normalization: An Evaluation Using a Randomized Dataset as the Benchmark

PubMed Central

Qin, Li-Xuan; Zhou, Qin

2014-01-01

MicroRNA arrays possess a number of unique data features that challenge the assumption key to many normalization methods. We assessed the performance of existing normalization methods using two microRNA array datasets derived from the same set of tumor samples: one dataset was generated using a blocked randomization design when assigning arrays to samples and hence was free of confounding array effects; the second dataset was generated without blocking or randomization and exhibited array effects. The randomized dataset was assessed for differential expression between two tumor groups and treated as the benchmark. The non-randomized dataset was assessed for differential expression after normalization and compared against the benchmark. Normalization improved the true positive rate significantly in the non-randomized data but still possessed a false discovery rate as high as 50%. Adding a batch adjustment step before normalization further reduced the number of false positive markers while maintaining a similar number of true positive markers, which resulted in a false discovery rate of 32% to 48%, depending on the specific normalization method. We concluded the paper with some insights on possible causes of false discoveries to shed light on how to improve normalization for microRNA arrays. PMID:24905456

Imaging techniques for visualizing and phenotyping congenital heart defects in murine models.

PubMed

Liu, Xiaoqin; Tobita, Kimimasa; Francis, Richard J B; Lo, Cecilia W

2013-06-01

Mouse model is ideal for investigating the genetic and developmental etiology of congenital heart disease. However, cardiovascular phenotyping for the precise diagnosis of structural heart defects in mice remain challenging. With rapid advances in imaging techniques, there are now high throughput phenotyping tools available for the diagnosis of structural heart defects. In this review, we discuss the efficacy of four different imaging modalities for congenital heart disease diagnosis in fetal/neonatal mice, including noninvasive fetal echocardiography, micro-computed tomography (micro-CT), micro-magnetic resonance imaging (micro-MRI), and episcopic fluorescence image capture (EFIC) histopathology. The experience we have gained in the use of these imaging modalities in a large-scale mouse mutagenesis screen have validated their efficacy for congenital heart defect diagnosis in the tiny hearts of fetal and newborn mice. These cutting edge phenotyping tools will be invaluable for furthering our understanding of the developmental etiology of congenital heart disease. Copyright © 2013 Wiley Periodicals, Inc.

Chemical stability and electrical performance of dual-active-layered zinc-tin-oxide/indium-gallium-zinc-oxide thin-film transistors using a solution process.

PubMed

Kim, Chul Ho; Rim, You Seung; Kim, Hyun Jae

2013-07-10

We investigated the chemical stability and electrical properties of dual-active-layered zinc-tin-oxide (ZTO)/indium-gallium-zinc-oxide (IGZO) structures (DALZI) with the durability of the chemical damage. The IGZO film was easily corroded or removed by an etchant, but the DALZI film was effectively protected by the high chemical stability of ZTO. Furthermore, the electrical performance of the DALZI thin-film transistor (TFT) was improved by densification compared to the IGZO TFT owing to the passivation of the pin holes or pore sites and the increase in the carrier concentration due to the effect of Sn(4+) doping.

TFT-Directed Electroplating of RGB Luminescent Films without a Vacuum or Mask toward a Full-Color AMOLED Pixel Matrix.

PubMed

Wang, Rong; Zhang, Donglian; Xiong, You; Zhou, Xuehong; Liu, Cao; Chen, Weifeng; Wu, Weijing; Zhou, Lei; Xu, Miao; Wang, Lei; Liu, Linlin; Peng, Junbiao; Ma, Yuguang; Cao, Yong

2018-05-30

The thin-film transistor (TFT) driving circuit is a separate electronic component embedded within the panel itself to switch the current for each pixel in active-matrix organic light-emitting diode displays. We reported a TFT-directed dye electroplating method to fabricate pixels; this would be a new method to deposit films on prepatterned electrode for organic full-color display, where TFT driving circuit provide a switching current signal to drive and direct dye depositing on selected RGB pixels. A prototype patterned color pixel matrix was achieved, as high-quality light-emitting films with uniform morphology, pure RGB chromaticity, and stable output.

MicroRNAs in the pathobiology of atherosclerosis

PubMed Central

Laffont, Benoit; Rayner, Katey J

2017-01-01

MicroRNAs are short non-coding RNAs, expressed in humans and involved in sequence-specific post-transcriptional regulation of gene expression. They have emerged as key players in a wide array of biological processes, and changes in their expression and/or function have been associated with plethora of human diseases. Atherosclerosis and its related clinical complications, such as myocardial infarction or stroke, represent the leading cause of death in the western world. Accumulating experimental evidence has revealed a key role for microRNAs in regulating cellular and molecular processes related to atherosclerosis development, ranging from risk factors, to plaque initiation and progression, up to atherosclerotic plaque rupture. In this review, we will focus on how microRNAs can influence atherosclerosis biology, as well as the potential clinical applications of microRNAs which are being developed as both targets and therapeutics for a growing industry hoping to harness the power of RNA-guided gene regulation to fight disease and infection. PMID:28232017

New-style defect inspection system of film

NASA Astrophysics Data System (ADS)

Liang, Yan; Liu, Wenyao; Liu, Ming; Lee, Ronggang

2002-09-01

An inspection system has been developed for on-line detection of film defects, which bases on combination of photoelectric imaging and digital image processing. The system runs in high speed of maximum 60m/min. Moving film is illuminated by LED array which emits even infrared (peak wavelength λp=940nm), and infrared images are obtained with a high quality and high speed CCD camera. The application software based on Visual C++6.0 under Windows processes images in real time by means of such algorithms as median filter, edge detection and projection, etc. The system is made up of four modules, which are introduced in detail in the paper. On-line experiment results shows that the inspection system can recognize defects precisely in high speed and run reliably in practical application.

Quantum correlation of path-entangled two-photon states in waveguide arrays with defects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dou, Yiling; Xu, Lei; Han, Bin

We study the quantum correlation of path-entangled states of two photons in coupled one-dimensional waveguide arrays with lattice defects. Both off-diagonal and diagonal defects are considered, which show different effects on the quantum correlation of path-entangled two-photon states. Two-photon bunching or anti-bunching effects can be observed and controlled. The two photons are found to have a tendency to bunch at the side lobes with a repulsive off-diagonal defect, and the path-entanglement of the input two-photon state can be preserved during the propagation. We also found that defect modes may play an important role on the two-photon correlation of path-entangled statesmore » in the waveguide arrays. Due to the quantum interference effect, intriguing evolution dynamics of the two-photon correlation matrix elements with oscillation frequencies being either twice of or the same as that of a classical light wave, depending on the position of the correlation matrix element, is observed. Our results show that it is possible to manipulate the two-photon correlation properties of path-entangled states in waveguide arrays with lattice defects.« less

Hard and flexible optical printed circuit board

NASA Astrophysics Data System (ADS)

Lee, El-Hang; Lee, Hyun Sik; Lee, S. G.; O, B. H.; Park, S. G.; Kim, K. H.

2007-02-01

We report on the design and fabrication of hard and flexible optical printed circuit boards (O-PCBs). The objective is to realize generic and application-specific O-PCBs, either in hard form or flexible form, that are compact, light-weight, low-energy, high-speed, intelligent, and environmentally friendly, for low-cost and high-volume universal applications. The O-PCBs consist of 2-dimensional planar arrays of micro/nano-scale optical wires, circuits and devices that are interconnected and integrated to perform the functions of sensing, storing, transporting, processing, switching, routing and distributing optical signals on flat modular boards. For fabrication, the polymer and organic optical wires and waveguides are first fabricated on a board and are used to interconnect and integrate micro/nano-scale photonic devices. The micro/nano-optical functional devices include lasers, detectors, switches, sensors, directional couplers, multi-mode interference devices, ring-resonators, photonic crystal devices, plasmonic devices, and quantum devices. For flexible boards, the optical waveguide arrays are fabricated on flexible poly-ethylen terephthalate (PET) substrates by UV embossing. Electrical layer carrying VCSEL and PD array is laminated with the optical layer carrying waveguide arrays. Both hard and flexible electrical lines are replaced with high speed optical interconnection between chips over four waveguide channels up to 10Gbps on each. We discuss uses of hard or flexible O-PCBs for telecommunication systems, computer systems, transportation systems, space/avionic systems, and bio-sensor systems.

Achieving high carrier mobility exceeding 70 cm2/Vs in amorphous zinc tin oxide thin-film transistors

NASA Astrophysics Data System (ADS)

Kim, Sang Tae; Shin, Yeonwoo; Yun, Pil Sang; Bae, Jong Uk; Chung, In Jae; Jeong, Jae Kyeong

2017-09-01

This paper proposes a new defect engineering concept for low-cost In- and Ga-free zinc tin oxide (ZTO) thin-film transistors (TFTs). This concept is comprised of capping ZTO films with tantalum (Ta) and a subsequent modest thermal annealing treatment at 200 °C. The Ta-capped ZTO TFTs exhibited a remarkably high carrier mobility of 70.8 cm2/Vs, low subthreshold gate swing of 0.18 V/decade, threshold voltage of -1.3 V, and excellent ION/OFF ratio of 2 × 108. The improvement (> two-fold) in the carrier mobility compared to the uncapped ZTO TFT can be attributed to the effective reduction of the number of adverse tailing trap states, such as hydroxyl groups or oxygen interstitial defects, which stems from the scavenging effect of the Ta capping layer on the ZTO channel layer. Furthermore, the Ta-capped ZTO TFTs showed excellent positive and negative gate bias stress stabilities. [Figure not available: see fulltext.

Electrical and mechanical characteristics of fully transparent IZO thin-film transistors on stress-relieving bendable substrates

NASA Astrophysics Data System (ADS)

Park, Sukhyung; Cho, Kyoungah; Oh, Hyungon; Kim, Sangsig

2016-10-01

In this study, we report the electrical and mechanical characteristics of fully transparent indium zinc oxide (IZO) thin-film transistors (TFTs) fabricated on stress-relieving bendable substrates. An IZO TFT on a stress-relieving substrate can operate normally at a bending radius of 6 mm, while an IZO TFT on a normal plastic substrate fails to operate normally at a bending radius of 15 mm. A plastic island with high Young's modulus embedded on a soft elastomer layer with low Young's modulus plays the role of a stress-relieving substrate for the operation of the bent IZO TFT. The stress and strain distributions over the IZO TFT will be analyzed in detail in this paper.

Defectivity control of aluminum chemical mechanical planarization in replacement metal gate process of MOSFET

NASA Astrophysics Data System (ADS)

Jin, Zhang; Yuling, Liu; Chenqi, Yan; Yangang, He; Baohong, Gao

2016-04-01

The replacement metal gate (RMG) defectivity performance control is very challenging in high-k metal gate (HKMG) chemical mechanical polishing (CMP). In this study, three major defect types, including fall-on particles, micro-scratch and corrosion have been investigated. The research studied the effects of polishing pad, pressure, rotating speed, flow rate and post-CMP cleaning on the three kinds of defect, which finally eliminated the defects and achieved good surface morphology. This study will provide an important reference value for the future research of aluminum metal gate CMP. Project supported by the Major National Science and Technology Special Projects (No. 2009ZX02308), the Natural Science Foundation for the Youth of Hebei Province (Nos. F2012202094, F2015202267), and the Outstanding Youth Science and Technology Innovation Fund of Hebei University of Technology (No. 2013010).

Size dependence of 13C nuclear spin-lattice relaxation in micro- and nanodiamonds

NASA Astrophysics Data System (ADS)

Panich, A. M.; Sergeev, N. A.; Shames, A. I.; Osipov, V. Yu; Boudou, J.-P.; Goren, S. D.

2015-02-01

Size dependence of physical properties of nanodiamond particles is of crucial importance for various applications in which defect density and location as well as relaxation processes play a significant role. In this work, the impact of defects induced by milling of micron-sized synthetic diamonds was studied by magnetic resonance techniques as a function of the particle size. EPR and 13C NMR studies of highly purified commercial synthetic micro- and nanodiamonds were done for various fractions separated by sizes. Noticeable acceleration of 13C nuclear spin-lattice relaxation with decreasing particle size was found. We showed that this effect is caused by the contribution to relaxation coming from the surface paramagnetic centers induced by sample milling. The developed theory of the spin-lattice relaxation for such a case shows good compliance with the experiment.

Amorphous and crystalline TiO2 nanotube arrays for enhanced Li-ion intercalation properties.

PubMed

Guan, Dongsheng; Cai, Chuan; Wang, Ying

2011-04-01

We have employed a simple process of anodizing Ti foils to prepare TiO2 nanotube arrays which show enhanced electrochemical properties for applications as Li-ion battery electrode materials. The lengths and pore diameters of TiO2 nanotubes can be finely tuned by varying voltage, electrolyte composition, or anodization time. The as-prepared nanotubes are amorphous and can be converted into anatase nanotubes with heat treatment at 480 degrees C. Rutile crystallites emerge in the anatase nanotube when the annealing temperature is increased to 580 degrees C, resulting in TiO2 nanotubes of mixed phases. The morphological features of nanotubes remain unchanged after annealing. Li-ion insertion performance has been studied for amorphous and crystalline TiO2 nanotube arrays. Amorphous nanotubes with a length of 3.0 microm and an outer diameter of 125 nm deliver a capacity of 91.2 microA h cm(-2) at a current density of 400 microA cm(-2), while those with a length of 25 microm and an outer diameter of 158 nm display a capacity of 533 microA h cm-2. When the 3-microm long nanotubes become crystalline, they deliver lower capacities: the anatase nanotubes and nanotubes of mixed phases show capacities of 53.8 microA h cm-2 and 63.1 microA h cm(-2), respectively at the same current density. The amorphous nanotubes show excellent capacity retention ability over 50 cycles. The cycled nanotubes show little change in morphology compared to the nanotubes before electrochemical cycling. All the TiO2 nanotubes demonstrate higher capacities than amorphous TiO2 compact layer reported in literature. The amorphous TiO2 nanotubes with a length of 1.9 microm exhibit a capacity five times higher than that of TiO2 compact layer even when the nanotube array is cycled at a current density 80 times higher than that for the compact layer. These results suggest that anodic TiO2 nanotube arrays are promising electrode materials for rechargeable Li-ion batteries.

Longitudinal evaluation of thyroid autoimmunity and function in pregnant Korean women.

PubMed

Han, Seong-Min; Han, Jeong Hee; Park, Jina A; Quinn, Frank A; Park, Joonseok; Oh, Eunsuk

2013-12-01

Maternal thyroid dysfunction during pregnancy has been associated with adverse outcomes for both the mother and child. For this reason, it is important to understand thyroid status in pregnant women. However, there are relatively few published studies that examine thyroid function tests (TFT) and thyroid autoimmunity in non-Western pregnant women. Serum samples were longitudinally collected throughout pregnancy from 108 Korean women. TFT, thyroid peroxidase antibodies (TPO-Ab), and thyroglobulin antibodies (Tg-Ab) testing was performed. The impact of gestational age on TPO-Ab and Tg-Ab levels was evaluated and gestational age-specific reference intervals for TFT were established in antibody negative women. In the first trimester, TPO-Ab and Tg-Ab were positive in 13.9% and 16.7% of women, respectively. For antibody positive women, median autoantibody levels for TPO-Ab and Tg-Ab dropped from first trimester to near term (133.7-10.5 IU/mL, and 162.1-21.9 IU/mL, respectively). Antibody status influenced thyroid stimulating hormone (TSH) during the first trimester, and TSH, free T4 (FT4) and total T4 (TT4) in the early second trimester. Later in gestation, no significant differences in TFT were found based on antibody status. Gestational age-specific reference intervals for TFT were calculated in antibody negative women. Laboratory evidence of autoimmune thyroid disease (AITD) is common in this population of pregnant Korean women. Antibody status influences TFT values in the first and early second trimester. Thyroid autoantibody status and titer change in an individual-specific manner throughout pregnancy. Gestational age-specific reference intervals should be utilized for interpretation of TFT results in pregnant women.

Adhesion characterization and defect sizing of sandwich honeycomb composites.

PubMed

Ndiaye, Elhadji Barra; Maréchal, Pierre; Duflo, Hugues

2015-09-01

Defects may appear in composite structures during their life cycle. A 10MHz 128 elements phased array transducer was investigated to characterize join bonds and defects in sandwich honeycomb composite structures. An adequate focal law throughout the composite skin gives the ultrasonic dispersive properties of the composite skin and glue layer behind. The resulting B-scan cartographies allow characterizing locally the honeycomb adhesion. Experimental measurements are compared in good agreement with the Debye Series Method (DSM). In the processed C-scan image, flaws are detectable and measurable, localized both in the scanning plane and in the thickness of the composite skin. Copyright © 2015 Elsevier B.V. All rights reserved.

Hydroxo radicals, C-H activation, and Pt-C bond formation from 77 K photolysis of a platinum(IV) hydroxo complex.

PubMed

Wickramasinghe, Lasantha A; Sharp, Paul R

2014-11-17

Photolysis (380 nm) of trans,cis-Pt(PEt3)2(Cl)2(OH)(4-tft) (4-tft = 4-trifluoromethylphenyl) at 77 K in 2-methyltetrahydrofuran gives triplet emission, platinum(III), and a hydroxo radical. Benzyl radical emission is observed in toluene from the reaction of a portion of the OH radicals with toluene. Warming the photolyzed solutions gives platinacycle trans-Pt(CH2CH2PEt2)(PEt3)(Cl)2(4-tft) by hydrogen-atom abstraction from a PEt3 ligand and trans-Pt(PEt3)2(Cl)(4-tft) from net HOCl photoelimination. The platinacycle undergoes thermal reductive elimination at 298 K or photolytic reductive elimination, even at 77 K.

Identification and Deletion of Tft1, a Predicted Glycosyltransferase Necessary for Cell Wall β-1,3;1,4-Glucan Synthesis in Aspergillus fumigatus

PubMed Central

Samar, Danial; Kieler, Joshua B.; Klutts, J. Stacey

2015-01-01

Aspergillus fumigatus is an environmental mold that causes severe, often fatal invasive infections in immunocompromised patients. The search for new antifungal drug targets is critical, and the synthesis of the cell wall represents a potential area to find such a target. Embedded within the main β-1,3-glucan core of the A. fumigatus cell wall is a mixed linkage, β-D-(1,3;1,4)-glucan. The role of this molecule or how it is synthesized is unknown, though it comprises 10% of the glucans within the wall. While this is not a well-studied molecule in fungi, it has been studied in plants. Using the sequences of two plant mixed linkage glucan synthases, a single ortholog was identified in A. fumigatus (Tft1). A strain lacking this enzyme (tft1Δ) was generated along with revertant strains containing the native gene under the control of either the native or a strongly expressing promoter. Immunofluorescence staining with an antibody against β-(1,3;1,4)-glucan and biochemical quantification of this polysaccharide in the tft1Δ strain demonstrated complete loss of this molecule. Reintroduction of the gene into the knockout strain yielded reappearance in amounts that correlated with expected expression of the gene. The loss of Tft1 and mixed linkage glucan yielded no in vitro growth phenotype. However, there was a modest increase in virulence for the tft1Δ strain in a wax worm model. While the precise roles for β-(1,3;1,4)-glucan within A. fumigatus cell wall are still uncertain, it is clear that Tft1 plays a pivotal role in the biosynthesis of this cell wall polysaccharide. PMID:25723175

Two-Thumb Encircling Technique Over the Head of Patients in the Setting of Lone Rescuer Infant CPR Occurred During Ambulance Transfer: A Crossover Simulation Study.

PubMed

Jo, Choong Hyun; Cho, Gyu Chong; Lee, Chang Hee

2017-07-01

The purpose of this study was to determine if the over-the-head 2-thumb encircling technique (OTTT) provides better overall quality of cardiopulmonary resuscitation compared with conventional 2-finger technique (TFT) for a lone rescuer in the setting of infant cardiac arrest in ambulance. Fifty medical emergency service students were voluntarily recruited to perform lone rescuer infant cardiopulmonary resuscitation for 2 minutes on a manikin simulating a 3-month-old baby in an ambulance. Participants who performed OTTT sat over the head of manikins to compress the chest using a 2-thumb encircling technique and provide bag-valve mask ventilations, whereas those who performed TFT sat at the side of the manikins to compress using 2-fingers and provide pocket-mask ventilations. Mean hands-off time was not significantly different between OTTT and TFT (7.6 ± 1.1 seconds vs 7.9 ± 1.3 seconds, P = 0.885). Over-the-head 2-thumb encircling technique resulted in greater depth of compression (42.6 ± 1.4 mm vs 41.0 ± 1.4 mm, P < 0.001) and faster rate of compressions (114.4 ± 8.0 per minute vs 112.2 ± 8.2 per minute, P = 0.019) than TFT. Over-the-head 2-thumb encircling technique resulted in a smaller fatigue score than TFT (1.7 ± 1.5 vs 2.5 ± 1.6, P < 0.001). In addition, subjects reported that compression, ventilation, and changing compression to ventilation were easier in OTTT than in TFT. The use of OTTT may be a suitable alternative to TFT in the setting of cardiac arrest of infants during ambulance transfer.

Array microscopy technology and its application to digital detection of Mycobacterium tuberculosis

NASA Astrophysics Data System (ADS)

McCall, Brian P.

Tuberculosis causes more deaths worldwide than any other curable infectious disease. This is the case despite tuberculosis appearing to be on the verge of eradication midway through the last century. Efforts at reversing the spread of tuberculosis have intensified since the early 1990s. Since then, microscopy has been the primary frontline diagnostic. In this dissertation, advances in clinical microscopy towards array microscopy for digital detection of Mycobacterium tuberculosis are presented. Digital array microscopy separates the tasks of microscope operation and pathogen detection and will reduce the specialization needed in order to operate the microscope. Distributing the work and reducing specialization will allow this technology to be deployed at the point of care, taking the front-line diagnostic for tuberculosis from the microscopy center to the community health center. By improving access to microscopy centers, hundreds of thousands of lives can be saved. For this dissertation, a lens was designed that can be manufactured as 4x6 array of microscopes. This lens design is diffraction limited, having less than 0.071 waves of aberration (root mean square) over the entire field of view. A total area imaged onto a full-frame digital image sensor is expected to be 3.94 mm2, which according to tuberculosis microscopy guidelines is more than sufficient for a sensitive diagnosis. The design is tolerant to single point diamond turning manufacturing errors, as found by tolerance analysis and by fabricating a prototype. Diamond micro-milling, a fabrication technique for lens array molds, was applied to plastic plano-concave and plano-convex lens arrays, and found to produce high quality optical surfaces. The micro-milling technique did not prove robust enough to produce bi-convex and meniscus lens arrays in a variety of lens shapes, however, and it required lengthy fabrication times. In order to rapidly prototype new lenses, a new diamond machining technique was developed called 4-axis single point diamond machining. This technique is 2-10x faster than micro-milling, depending on how advanced the micro-milling equipment is. With array microscope fabrication still in development, a single prototype of the lens designed for an array microscope was fabricated using single point diamond turning. The prototype microscope objective was validated in a pre-clinical trial. The prototype was compared with a standard clinical microscope objective in diagnostic tests. High concordance, a Fleiss's kappa of 0.88, was found between diagnoses made using the prototype and standard microscope objectives and a reference test. With the lens designed and validated and an advanced fabrication process developed, array microscopy technology is advanced to the point where it is feasible to rapidly prototype an array microscope for detection of tuberculosis and translate array microscope from an innovative concept to a device that can save lives.

Development of optics with micro-LED arrays for improved opto-electronic neural stimulation

NASA Astrophysics Data System (ADS)

Chaudet, Lionel; Neil, Mark; Degenaar, Patrick; Mehran, Kamyar; Berlinguer-Palmini, Rolando; Corbet, Brian; Maaskant, Pleun; Rogerson, David; Lanigan, Peter; Bamberg, Ernst; Roska, Botond

2013-03-01

The breakthrough discovery of a nanoscale optically gated ion channel protein, Channelrhodopsin 2 (ChR2), and its combination with a genetically expressed ion pump, Halorhodopsin, allowed the direct stimulation and inhibition of individual action potentials with light alone. This work reports developments of ultra-bright elec­ tronically controlled optical array sources with enhanced light gated ion channels and pumps for use in systems to further our understanding of both brain and visual function. This work is undertaken as part of the European project, OptoNeuro. Micro-LED arrays permit spatio-temporal control of neuron stimulation on sub-millisecond timescales. However they are disadvantaged by their broad spatial light emission distribution and low fill factor. We present the design and implementation of a projection and micro-optics system for use with a micro-LED array consisting of a 16x16 matrix of 25 μm diameter micro-LEDs with 150 μm centre-to-centre spacing and an emission spectrum centred at 470 nm overlapping the peak sensitivity of ChR2 and its testing on biological samples. The projection system images the micro-LED array onto micro-optics to improve the fill-factor from ~2% to more than 78% by capturing a larger fraction of the LED emission and directing it correctly to the sample plane. This approach allows low fill factor arrays to be used effectively, which in turn has benefits in terms of thermal management and electrical drive from CMOS backplane electronics. The entire projection system is integrated into a microscope prototype to provide stimulation spots at the same size as the neuron cell body (μ10 pm).

Fabrication of a Polymer Micro Needle Array by Mask-Dragging X-Ray Lithography and Alignment X-Ray Lithography

NASA Astrophysics Data System (ADS)

Li, Yi-Gui; Yang, Chun-Sheng; Liu, Jing-Quan; Sugiyama, Susumu

2011-03-01

Polymer materials such as transparent thermoplastic poly(methyl methacrylate) (PMMA) have been of great interest in the research and development of integrated circuits and micro-electromechanical systems due to their relatively low cost and easy process. We fabricated PMMA-based polymer hollow microneedle arrays by mask-dragging and aligning x-ray lithography. Techniques for 3D micromachining by direct lithography using x-rays are developed. These techniques are based on using image projection in which the x-ray is used to illuminate an appropriate gold pattern on a polyimide film mask. The mask is imaged onto the PMMA sample. A pattern with an area of up to 100 × 100mm2 can be fabricated with sub-micron resolution and a highly accurate order of a few microns by using a dragging mask. The fabrication technology has several advantages, such as forming complex 3D micro structures, high throughput and low cost.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bolat, S., E-mail: bolat@ee.bilkent.edu.tr, E-mail: aokyay@ee.bilkent.edu.tr; Tekcan, B.; UNAM, National Nanotechnology Research Center, Bilkent University, Ankara 06800

We report GaN thin film transistors (TFT) with a thermal budget below 250 °C. GaN thin films are grown at 200 °C by hollow cathode plasma-assisted atomic layer deposition (HCPA-ALD). HCPA-ALD-based GaN thin films are found to have a polycrystalline wurtzite structure with an average crystallite size of 9.3 nm. TFTs with bottom gate configuration are fabricated with HCPA-ALD grown GaN channel layers. Fabricated TFTs exhibit n-type field effect characteristics. N-channel GaN TFTs demonstrated on-to-off ratios (I{sub ON}/I{sub OFF}) of 10{sup 3} and sub-threshold swing of 3.3 V/decade. The entire TFT device fabrication process temperature is below 250 °C, which is the lowest process temperaturemore » reported for GaN based transistors, so far.« less

A randomized comparison of three chest compression techniques and associated hemodynamic effect during infant CPR: A randomized manikin study.

PubMed

Smereka, Jacek; Szarpak, Lukasz; Rodríguez-Núñez, Antonio; Ladny, Jerzy R; Leung, Steve; Ruetzler, Kurt

2017-10-01

Pediatric cardiac arrest is an uncommon but critical life-threatening event requiring effective cardiopulmonary resuscitation. High-quality cardio-pulmonary resuscitation (CPR) is essential, but is poorly performed, even by highly skilled healthcare providers. The recently described two-thumb chest compression technique (nTTT) consists of the two thumbs directed at the angle of 90° to the chest while having the fingers fist-clenched. This technique might facilitate adequate chest-compression depth, chest-compression rate and rate of full chest-pressure relief. 42 paramedics from the national Emergency Medical Service of Poland performed three single-rescuer CPR sessions for 10 minutes each. Each session was randomly assigned to the conventional two-thumb (TTHT), the conventional two-finger (TFT) or the nTTT. The manikin used for this study was connected with an arterial blood pressure measurement device and blood measurements were documented on a 10-seconds cycle. The nTTT provided significant higher systolic (82 vs. 30 vs. 41 mmHg). A statistically significant difference was noticed between nTTT and TFT (p<.001), nTTT and TTHT (p<0.001), TFT and TTHT (p=0.003). The median diastolic preassure using nTTT was 16 mmHg compared with 9 mmHg for TFT (p<0.001), and 9.5 mmHg for TTHT (p<0.001). Mean arterial pressure using distinct methods varied and amounted to 40 vs. 22. vs. 26 mmHg (nTTT vs. TFT vs. TTHT, respectively). A statistically significant difference was noticed between nTTT and TFT (p<0.001), nTTT and TTEHT (p<0.001), and TFT and TTHT (p<0.001). The highest median pulse pressure was obtained by the nTTT 67.5 mmHg. Pulse pressure was 31.5 mmHg in the TTHT and 24 mmHg in the TFT. The difference between TFT and TTHT (p=0.025), TFT and nTTT (p<0.001), as well as between TTHT and nTTT (p<0.001) were statistically significant. The new nTTT technique generated higher arterial blood pressures compared to established chest compression techniques using an infant manikin model, suggesting a more effective chest compression. Our results have important clinical implications as nTTT was simple to perform and could be widely taught to both healthcare professionals and bystanders. Whether this technique translates to improved outcomes over existing techniques needs further animal studies and subsequent human trials. Copyright © 2017 Elsevier Inc. All rights reserved.

Assessment laser phototherapy on bone defects grafted or not with biphasic synthetic micro-granular HA + β-tricalcium phosphate: histological study in an animal model

NASA Astrophysics Data System (ADS)

Soares, Luiz Guilherme P.; Marques, Aparecida M. C.; Aciole, Jouber Mateus S.; Trindade, Renan; Santos, Jean N.; Pinheiro, Antônio Luiz B.

2014-02-01

Beside of biomaterials, Laser phototherapy has shown positive results as auxiliary therapy on bone repair. The aim of this study was to evaluate, through histological analysis, the influence of Laser phototherapy in the process of repair of bone defects grafted or not with Hydroxyapatite. Forty rats were divided into 4 groups each subdivided into 2 subgroups according to the time of sacrifice. Surgical bone defects were made on femur of each animal with a trephine drill. On animals of group Clot the defect was filled only by blood, on group Laser the defect filled with the clot and further irradiated. In group Biomaterial the defect was filled with HA + β-TCP graft. In group Laser + Biomaterial, the defect was filled with biomaterial and further irradiated. The irradiation protocols were performed every 48 hours during for 15 days. Animal death occurred after 15 and 30 days. The specimens were routinely processed and evaluated by light microscopy. Qualitative analysis showed that group Laser + Biomaterial was in a more advanced stage of repair at the end of the experimental time. It was concluded that the Laser irradiation improved the repair of bone defects grafted or not.

Quantitative SIMS depth profiling of diffusion barrier gate-oxynitride structures in TFT-LCDs.

PubMed

Dreer, Sabine; Wilhartitz, Peter; Piplits, Kurt; Mayerhofer, Karl; Foisner, Johann; Hutter, Herbert

2004-06-01

Gate oxynitride structures of TFT-LCDs were investigated by SIMS, and successful solutions are demonstrated to overcome difficulties arising due to the charging effects of the multilayer systems, the matrix effect of the method, and the small pattern sizes of the samples. Because of the excellent reproducibility achieved by applying exponential relative sensitivity functions for quantitative analysis, minor differences in the barrier gate-oxynitride composition deposited on molybdenum capped aluminium-neodymium metallisation electrodes were determined between the centre and the edge of the TFT-LCD substrates. No differences were found for molybdenum-tungsten metallisations. Furthermore, at the edge of the glass substrates, aluminium, neodymium, and molybdenum SIMS depth profiles show an exponential trend. With TEM micrographs an inhomogeneous thickness of the molybdenum capping is revealed as the source of this effect, which influences the electrical behaviour of the device. The production process was improved after these results and the aging behaviour of TFT-LCDs was investigated in order to explain the change in control voltage occurring during the lifetime of the displays. SIMS and TEM show an enrichment of neodymium at the interface to the molybdenum layer, confirming good diffusion protection of the molybdenum barrier during accelerated aging. The reason for the shift of the control voltage was finally located by semi-quantitative depth profiling of the sodium diffusion originating from the glass substrate. Molybdenum-tungsten was a much better buffer for the highly-mobile charge carriers than aluminium-neodymium. Best results were achieved with PVD silicon oxynitride as diffusion barrier and gate insulator deposited on aluminium-neodymium metallisation layers.

Tear secretion dysfunction among women workers engaged in light-on tests in the TFT-LCD industry.

PubMed

Su, Shih-Bin; Lu, Chih-Wei; Sheen, Jiunn-Woei; Kuo, Shu-Chun; Guo, How-Ran

2006-12-16

The TFT-LCD (thin film transistor liquid crystal display) industry is rapidly growing in Taiwan and many other countries. A large number of workers, mainly women, are employed in the light-on test process to detect the defects of products. At the light-on test workstation, the operator is generally exposed to low humidity (in the clean room environment), flashing light, and low ambient illumination for long working hours. Many workers complained about eye discomfort, and therefore we conducted a study to evaluate the tear secretion function of light-on test workers of a TFT-LCD company. We recruited workers engaged in light-on tests in the company during their periodical health examination. In addition to a questionnaire survey of demographic characteristics and ophthalmic symptoms, we evaluated the tear secretion function of both eyes of each participant using the Schirmer's lacrimal basal secretion test with anaesthesia. A participant with one or both eyes yielding abnormal test results was defined as a case of tear secretion dysfunction. During the study period, a total of 371 light-on test workers received the health examination at the clinic of the park, and 52 of them were excluded due to having ophthalmic diseases and other systemic diseases that may affect ophthalmic function. All the remaining 319 qualified workers agreed to participate in this study, and they were all females working by 4-shift rotations. The average age was 24.2 years old (standard deviation [SD] = 3.8), and the average employment duration was 13.6 months (SD = 5.7). Among the 11 ophthalmic symptoms evaluated, eye dryness was the most prevalent (prevalence = 43.3%). In addition, the prevalence of tear secretion dysfunction in at least one eye was 40.1% (128 cases), and contact lens users had an odds ratio of 1.73 (95% confidence interval = 1.02-2.94) in comparison with non-contact lens users. Comparing the Schirmer's test results of those who also participated in the screening in the previous year, we found 40 of the 156 participants (17.2%) with normal test results in the previous year turned abnormal in 2001. In contrast, only 21 of the 76 participants (9.1%) with abnormal test results in the previous year turned normal, and the difference was statistically significant (p = 0.02 for McNemar's test). The prevalence of tear secretion dysfunction in woman workers engaged in light-on tests is high and increases with a one-year duration of employment. The use of contact lens may further increase the risk.

Development of methods for the analysis of multi-mode TFM images

NASA Astrophysics Data System (ADS)

Sy, K.; Bredif, P.; Iakovleva, E.; Roy, O.; Lesselier, D.

2018-05-01

TFM (Total Focusing Method) is an advanced post-processing imaging algorithm of ultrasonic array data that shows good potential in defect detection and characterization. It can be employed using an infinite number of paths between transducer and focusing point. Depending upon the geometry and the characteristics of the defect in a given part, there are not the same modes that are appropriate for the defect reconstruction. Furthermore, non-physical indications can be observed, prone to misinterpretation. These imaging artifacts are due to the coexistence of several contributions involving several modes of propagation and interactions with possible defects and/or the geometry of the part. Two methods for filtering artifacts and reducing the number of TFM images are developed and illustrated.

Fabrication of amorphous InGaZnO thin-film transistor with solution processed SrZrO3 gate insulator

NASA Astrophysics Data System (ADS)

Takahashi, Takanori; Oikawa, Kento; Hoga, Takeshi; Uraoka, Yukiharu; Uchiyama, Kiyoshi

2017-10-01

In this paper, we describe a method of fabrication of thin film transistors (TFTs) with high dielectric constant (high-k) gate insulator by a solution deposition. We chose a solution processed SrZrO3 as a gate insulator material, which possesses a high dielectric constant of 21 with smooth surface. The IGZO-TFT with solution processed SrZrO3 showed good switching property and enough saturation features, i.e. field effect mobility of 1.7cm2/Vs, threshold voltage of 4.8V, sub-threshold swing of 147mV/decade, and on/off ratio of 2.3×107. Comparing to the TFTs with conventional SiO2 gate insulator, the sub-threshold swing was improved by smooth surface and high field effect due to the high dielectric constant of SrZrO3. These results clearly showed that use of solution processed high-k SrZrO3 gate insulator could improve sub-threshold swing. In addition, the residual carbon originated from organic precursors makes TFT performances degraded.

Simulation and experiment for the inspection of stainless steel bolts in servicing using an ultrasonic phased array

NASA Astrophysics Data System (ADS)

Chen, Jinzhong; He, Renyang; Kang, Xiaowei; Yang, Xuyun

2015-10-01

The non-destructive testing of small-sized (M12-M20) stainless steel bolts in servicing is always a technical problem. This article focuses on the simulation and experimental research of stainless steel bolts with an artificial defect reflector using ultrasonic phased array inspection. Based on the observation of the sound field distribution of stainless steel bolts in ultrasonic phased array as well as simulation modelling and analysis of the phased array probes' detection effects with various defect sizes, different artificial defect reflectors of M16 stainless steel bolts are machined in reference to the simulation results. Next, those bolts are tested using a 10-wafer phased array probe with 5 MHz. The test results finally prove that ultrasonic phased array can detect 1-mm cracks in diameter with different depths of M16 stainless steel bolts and a metal loss of Φ1 mm of through-hole bolts, which provides technical support for future non-destructive testing of stainless steel bolts in servicing.

Array automated assembly task, phase 2. Low cost silicon solar array project

NASA Technical Reports Server (NTRS)

Rhee, S. S.; Jones, G. T.; Allison, K. T.

1978-01-01

Several modifications instituted in the wafer surface preparation process served to significantly reduce the process cost to 1.55 cents per peak watt in 1975 cents. Performance verification tests of a laser scanning system showed a limited capability to detect hidden cracks or defects, but with potential equipment modifications this cost effective system could be rendered suitable for applications. Installation of electroless nickel plating system was completed along with an optimization of the wafer plating process. The solder coating and flux removal process verification test was completed. An optimum temperature range of 500-550 C was found to produce uniform solder coating with the restriction that a modified dipping procedure is utilized. Finally, the construction of the spray-on dopant equipment was completed.

Depth of array micro-holes with large aspect ratio in Al based cast alloy

NASA Astrophysics Data System (ADS)

Jin, Meiling; Qu, Yingdong; Li, Rongde

2018-03-01

In order to study on the depth of array micro-holes on Al base cast alloy, micro-hole with depth of 50 mm and diameter of 0.55 mm are successfully prepared by using poor wetting between carbon and Al. Accordingly, the mold of depth is established, the results show that calculated depth of micro-hole is 53.22 mm, relative error is 6% compare with the actual measured depth, and the depth of hole exponentially increases with the increasing of distance between two micro-holes. Surface tension and metallostatic pressure of metal molten are mainly affecting factors for depth of micro-holes.

Enhanced lifetime for thin-dielectric microdischarge-arrays operating in DC

NASA Astrophysics Data System (ADS)

Dussart, Remi; Felix, Valentin; Overzet, Lawrence; Aubry, Olivier; Stolz, Arnaud; Lefaucheux, Philippe; Gremi-Univ Orleans-Cnrs Collaboration; University Of Texas At Dallas Collaboration

2016-09-01

Micro-hollow cathode discharge arrays using silicon as the cathode have a very limited lifetime because the silicon bubbles and initiates micro-arcing. To avoid this destructive behavior, the same configuration was kept but, another material was selected for the cathode. Using micro and nanotechnologies ordinarily used in microelectronic and MEMS device fabrication, we made arrays of cathode boundary layer (CBL)-type microreactors consisting of nickel electrodes separated by a 6 µm thick SiO2 layer. Microdischarges were ignited in arrays of 100 µm diameter holes at different pressures (200750 Torr) in different gases. Electrical and optical measurements were made to characterize the arrays. Unlike the microdischarges produced using silicon cathodes, the Ni cathode discharges remain very stable with essentially no micro-arcing. DC currents between 50 and 900 µA flowed through each microreactor with a discharge voltage of typically 200 V. Stable V-I characteristics showing both the normal and abnormal regimes were observed and are consistent with the spread of the plasma over the cathode area. Due to their stability and lifetime, new applications of these DC, CBL-type microreactors can now be envisaged.

Critical evaluation of ex vivo restoration of carious equine maxillary cheek teeth infundibulae following high-pressure gas and micro-particle abrasion.

PubMed

Dixon, P M; Savill, D; Horbyl, A; Reardon, R J M; Liuti, T

2014-06-01

Infundibular caries of the equine maxillary cheek teeth is an important disorder that can lead to dental fracture or apical infection. Treatment by removing food debris and carious dental tissue from affected infundibulae using high-pressure abrasion with aluminium hydroxide micro-particles, followed by filling the cleaned defect with endodontic restorative materials is a recommended treatment. However, although anecdotally considered a successful treatment option, there is currently no objective evidence to support this claim. Forty maxillary cheek teeth (CT) that contained 55 infundibulae with caries (mainly grade 2) were extracted post-mortem from 21 adult horses. Five of the CT were sectioned prior to treatment to facilitate visual examination of the carious infundibulae. The remaining carious infundibulae were cleaned using high-pressure abrasion with aluminium hydroxide particles and five CT were sectioned to assess the efficacy of this cleaning process. The remaining 30 CT containing 39 carious infundibulae were then filled with a composite restorative material. The efficacy of this restoration was assessed by computed tomography imaging followed by direct visual examination after sectioning the teeth. Only 46% (18/39) of restored infundibulae, all with shallow (mean 9.6 mm deep) defects, were fully cleaned of food debris and carious material, and filled with restorative material to their full depth. Of these 18, 11 had peripheral defects around the restoration, leaving just 18% (7/39) of restorations without any gross defects. The remaining 54% (21/39) of infundibulae (mean depth of infundibular caries defect, 18.3 mm) still contained food debris and/or carious material in more apical locations, with infundibulae with the deepest caries defects being the least effectively cleaned. The findings of this study indicate that high-pressure micro-particle abrasion is only effective in cleaning food debris from shallow, carious CT infundibulae and consequently, the majority of subsequent infundibular restorations are imperfect. Copyright © 2014. Published by Elsevier Ltd.

The intrinsic role of membrane morphology to reduce defectivity in advanced photochemicals

NASA Astrophysics Data System (ADS)

Kohyama, Tetsu; Wu, Aiwen; Miura, Kozue; Ohyashiki, Yasushi

2018-03-01

Defect source reduction in leading-edge iArF resists is a critical requirement to improve device performance and overall yield in lithography manufacturing processes. It is believed that some polar polymers can aggregate and be responsible for single or multiple micro-bridge defects. Further investigation into the formation of these defects is needed. We have previously presented the effective removal of gel-like polymers using nylon media [1]. However, as the industry is moving to smaller feature sizes, there is a need to further improve the defect removal efficiency. In this paper, a filter, comprised of a novel membrane called Azora with unique morphology and high flow performance is introduced. This new filter shows better on-wafer in an advanced ArF solution than conventional Nylon and UPE media. In addition, it shows improved stability during chemical storage. Results and possible retention mechanisms are discussed.

Evaluation of a newly developed infant chest compression technique

PubMed Central

Smereka, Jacek; Bielski, Karol; Ladny, Jerzy R.; Ruetzler, Kurt; Szarpak, Lukasz

2017-01-01

Abstract Background: Providing adequate chest compression is essential during infant cardio-pulmonary-resuscitation (CPR) but was reported to be performed poor. The “new 2-thumb technique” (nTTT), which consists in using 2 thumbs directed at the angle of 90° to the chest while closing the fingers of both hands in a fist, was recently introduced. Therefore, the aim of this study was to compare 3 chest compression techniques, namely, the 2-finger-technique (TFT), the 2-thumb-technique (TTHT), and the nTTT in an randomized infant-CPR manikin setting. Methods: A total of 73 paramedics with at least 1 year of clinical experience performed 3 CPR settings with a chest compression:ventilation ratio of 15:2, according to current guidelines. Chest compression was performed with 1 out of the 3 chest compression techniques in a randomized sequence. Chest compression rate and depth, chest decompression, and adequate ventilation after chest compression served as outcome parameters. Results: The chest compression depth was 29 (IQR, 28–29) mm in the TFT group, 42 (40–43) mm in the TTHT group, and 40 (39–40) mm in the nTTT group (TFT vs TTHT, P < 0.001; TFT vs nTTT, P < 0.001; TTHT vs nTTT, P < 0.01). The median compression rate with TFT, TTHT, and nTTT varied and amounted to 136 (IQR, 133–144) min–1 versus 117 (115–121) min–1 versus 111 (109–113) min–1. There was a statistically significant difference in the compression rate between TFT and TTHT (P < 0.001), TFT and nTTT (P < 0.001), as well as TTHT and nTTT (P < 0.001). Incorrect decompressions after CC were significantly increased in the TTHT group compared with the TFT (P < 0.001) and the nTTT (P < 0.001) group. Conclusions: The nTTT provides adequate chest compression depth and rate and was associated with adequate chest decompression and possibility to adequately ventilate the infant manikin. Further clinical studies are necessary to confirm these initial findings. PMID:28383397

Evaluation of a newly developed infant chest compression technique: A randomized crossover manikin trial.

PubMed

Smereka, Jacek; Bielski, Karol; Ladny, Jerzy R; Ruetzler, Kurt; Szarpak, Lukasz

2017-04-01

Providing adequate chest compression is essential during infant cardio-pulmonary-resuscitation (CPR) but was reported to be performed poor. The "new 2-thumb technique" (nTTT), which consists in using 2 thumbs directed at the angle of 90° to the chest while closing the fingers of both hands in a fist, was recently introduced. Therefore, the aim of this study was to compare 3 chest compression techniques, namely, the 2-finger-technique (TFT), the 2-thumb-technique (TTHT), and the nTTT in an randomized infant-CPR manikin setting. A total of 73 paramedics with at least 1 year of clinical experience performed 3 CPR settings with a chest compression:ventilation ratio of 15:2, according to current guidelines. Chest compression was performed with 1 out of the 3 chest compression techniques in a randomized sequence. Chest compression rate and depth, chest decompression, and adequate ventilation after chest compression served as outcome parameters. The chest compression depth was 29 (IQR, 28-29) mm in the TFT group, 42 (40-43) mm in the TTHT group, and 40 (39-40) mm in the nTTT group (TFT vs TTHT, P < 0.001; TFT vs nTTT, P < 0.001; TTHT vs nTTT, P < 0.01). The median compression rate with TFT, TTHT, and nTTT varied and amounted to 136 (IQR, 133-144) min versus 117 (115-121) min versus 111 (109-113) min. There was a statistically significant difference in the compression rate between TFT and TTHT (P < 0.001), TFT and nTTT (P < 0.001), as well as TTHT and nTTT (P < 0.001). Incorrect decompressions after CC were significantly increased in the TTHT group compared with the TFT (P < 0.001) and the nTTT (P < 0.001) group. The nTTT provides adequate chest compression depth and rate and was associated with adequate chest decompression and possibility to adequately ventilate the infant manikin. Further clinical studies are necessary to confirm these initial findings.

Bottleneck limitations for microRNA-based therapeutics from bench to the bedside.

PubMed

Chen, Yan; Zhao, Hongliang; Tan, Zhijun; Zhang, Cuiping; Fu, Xiaobing

2015-03-01

MicroRNAs are endogenous non-coding small RNAs that repress expression of a broad array of target genes. Research into the role and underlying molecular events of microRNAs in disease processes and the potential of microRNAs as drug targets has expanded rapidly. Significant advances have been made in identifying the associations of microRNAs with cancers, viral infections, immune diseases, cardiovascular diseases, wound healing, biological development and other areas of medicine. However, because of intense competition and financial risks, there is a series of stringent criteria and conditions that must be met before microRNA-based therapeutics could be pursued as new drug candidates. In this review, we specifically emphasized the obstacles for bench-based microRNA to the bedside, including common barriers in basic research, application limitations while moving to the clinic at the aspects of vector delivery, off-target effects, toxicity mediation, immunological activation and dosage determination, which should be overcome before microRNA-based therapeutics take their place in the clinic.

Facile synthesis and electrochemical properties of continuous porous spheres assembled from defect-rich, interlayer-expanded, and few-layered MoS2/C nanosheets for reversible lithium storage

NASA Astrophysics Data System (ADS)

Chen, Biao; Lu, Huihui; Zhao, Naiqin; Shi, Chunsheng; Liu, Enzuo; He, Chunnian; Ma, Liying

2018-05-01

Hollow or continuous porous hierarchical MoS2/C structures with large Li-ion and electron transport kinetics, and high structural stability are urgent needs for their application in lithium ion batteries. In this regard, a novel continuous porous micro-sphere constructed from defect-rich, interlayer-expanded, and few-layered MoS2/C nanosheets is successfully synthesized through a facile one-pot hydrothermal method. The polyvinyl pyrrolidone surfactant serves as carbon source and supporter, while the CS2 works as soft template and sulfur source during hydrothermal process. The morphologies, structures, and electrochemical properties are systematically characterized. Importantly, it should be noted that the unique porous micro-spheres with merits of rich-defect, expanded-interlayer, few-layer (<5 layers), abundant pores and integrating carbon are favorable for lithium ion batteries application. When the uniform composites are used as lithium ion batteries anode materials, they deliver a high reversible capacity, excellent cycling performance (average capacity fading of 0.037% per cycle at 0.2 A g-1), and good rate capability.

Inverter Circuits using Pentacene and ZnO Transistors

NASA Astrophysics Data System (ADS)

Iechi, Hiroyuki; Watanabe, Yasuyuki; Kudo, Kazuhiro

2007-04-01

We report two types of integrated circuits based on a pentacene static-induction transistor (SIT), a pentacene thin-film transistor (TFT) and a zinc oxide (ZnO) TFT. The operating characteristics of a p-p inverter using pentacene SITs and a complementary inverter using a p-channel pentacene TFT and an n-channel ZnO TFT are described. The basic operation of logic circuits at a low voltage was achieved for the first time using the pentacene SIT inverter and complementary circuits with hybrid inorganic and organic materials. Furthermore, we describe the electrical properties of the ZnO films depending on sputtering conditions, and the complementary circuits using ZnO and pentacene TFTs.

Verification of computed tomographic estimates of cochlear implant array position: a micro-CT and histologic analysis.

PubMed

Teymouri, Jessica; Hullar, Timothy E; Holden, Timothy A; Chole, Richard A

2011-08-01

To determine the efficacy of clinical computed tomographic (CT) imaging to verify postoperative electrode array placement in cochlear implant (CI) patients. Nine fresh cadaver heads underwent clinical CT scanning, followed by bilateral CI insertion and postoperative clinical CT scanning. Temporal bones were removed, trimmed, and scanned using micro-CT. Specimens were then dehydrated, embedded in either methyl methacrylate or LR White resin, and sectioned with a diamond wafering saw. Histology sections were examined by 3 blinded observers to determine the position of individual electrodes relative to soft tissue structures within the cochlea. Electrodes were judged to be within the scala tympani, scala vestibuli, or in an intermediate position between scalae. The position of the array could be estimated accurately from clinical CT scans in all specimens using micro-CT and histology as a criterion standard. Verification using micro-CT yielded 97% agreement, and histologic analysis revealed 95% agreement with clinical CT results. A composite, 3-dimensional image derived from a patient's preoperative and postoperative CT images using a clinical scanner accurately estimates the position of the electrode array as determined by micro-CT imaging and histologic analyses. Information obtained using the CT method provides valuable insight into numerous variables of interest to patient performance such as surgical technique, array design, and processor programming and troubleshooting.

Genome-wide array-based comparative genomic hybridization (array-CGH) analysis in Aicardi Syndrome

USDA-ARS?s Scientific Manuscript database

Aicardi syndrome is characterized by agenesis of the corpus callosum, chorioretinal lacunae, severe seizures (starting as infantile spasms), neuronal migration defects, mental retardation, costovertebral defects, and typical facial features. Because Aicardi syndrome is sporadic and affects only fem...

Vitamin D insufficiency predicts time to first treatment (TFT) in early chronic lymphocytic leukemia (CLL).

PubMed

Molica, Stefano; Digiesi, Giovanna; Antenucci, Anna; Levato, Luciano; Mirabelli, Rosanna; Molica, Matteo; Gentile, Massimo; Giannarelli, Diana; Sperduti, Isabella; Morabito, Fortunato; Conti, Laura

2012-04-01

Although vitamin D insufficiency is related to inferior prognosis in some cancers, limited data exist in hematologic malignancies. We evaluated the relationship between 25(OH)D serum levels and time to first treatment (TFT), a disease-specific end point, in 130 previously untreated Binet stage A chronic lymphocytic leukemia (CLL) patients. Measurement of 25(OH)D was performed by means of a direct, competitive chemiluminescence immunoassay using the DiaSorin LIAISON 25(OH)D TOTAL assay (DiaSorin, Inc., Stillwater, Minnesota). Overall, 41 patients (31.5%) had severe vitamin D insufficiency (<10 ng/mL), 66 (50.7%) had mild to moderate insufficiency (10-24 ng/mL), and 23 (17.6%) had 25(OH)D levels within the optimal range (25-80 ng/mL), with no relationship with between the season of sample collection and 25(OH)D level (P=0.188). A patient stratification according to these 3 groups led to significant difference in terms of TFT, with vitamin D insufficient patients having the shortest TFT (P=0.02). With respect to continuous 25(OH)D levels and clinical outcome, TFT was shorter as 25(OH)D decreased until a value of 13.5 ng/mL at which point the association of 25(OH)D and TFT remained constant. As a matter of fact, the 25(OH)D value of 13.5 ng/mL identified two patients subsets with different TFT risk (HR=1.91; 95% CI=1.06-3.44; P=0.03). In multivariate analysis the variable entering the model at a significant level were mutational status of IgVH (P<0.0001), serum thymidine kinase (P=0.02) and absolute lymphocyte count (P=0.03). Thus confirming the Mayo clinic experience, our data provide further evidence that 25(OH)D levels may be an important host factor influencing TFT of Binet stage A patients. Whether normalizing vitamin D levels may delay disease-progression of patients with early disease will require testing in future trials. Copyright © 2011 Elsevier Ltd. All rights reserved.

Is there any alternative to standard chest compression techniques in infants? A randomized manikin trial of the new "2-thumb-fist" option.

PubMed

Ladny, Jerzy R; Smereka, Jacek; Rodríguez-Núñez, Antonio; Leung, Steve; Ruetzler, Kurt; Szarpak, Lukasz

2018-02-01

Pediatric cardiac arrest is a fatal emergent condition that is associated with high mortality, permanent neurological injury, and is a socioeconomic burden at both the individual and national levels. The aim of this study was to test in an infant manikin a new chest compression (CC) technique ("2 thumbs-fist" or nTTT) in comparison with standard 2-finger (TFT) and 2-thumb-encircling hands techniques (TTEHT). This was prospective, randomized, crossover manikin study. Sixty-three nurses who performed a randomized sequence of 2-minute continuous CC with the 3 techniques in random order. Simulated systolic (SBP), diastolic (DBP), mean arterial pressure (MAP), and pulse pressures (PP, SBP-DBP) in mm Hg were measured. The nTTT resulted in a higher median SBP value (69 [IQR, 63-74] mm Hg) than TTEHT (41.5 [IQR, 39-42] mm Hg), (P < .001) and TFT (26.5 [IQR, 25.5-29] mm Hg), (P <.001). The simulated median value of DBP was 20 (IQR, 19-20) mm Hg with nTTT, 18 (IQR, 17-19) mm Hg with TTEHT and 23.5 (IQR, 22-25.5) mm Hg with TFT. DBP was significantly higher with TFT than with TTEHT (P <.001), as well as with TTEHT than nTTT (P <.001). Median values of simulated MAP were 37 (IQR, 34.5-38) mm Hg with nTTT, 26 (IQR, 25-26) mm Hg with TTEHT and 24.5 (IQR,23.5-26.5) mm Hg with TFT. A statistically significant difference was noticed between nTTT and TFT (P <.001), nTTT and TTEHT (P <.001), and between TTEHT and TFT (P <.001). Sixty-one subjects (96.8%) preferred the nTTT over the 2 standard methods. The new nTTT technique achieved higher SBP and MAP compared to the standard CC techniques in our infant manikin model. nTTT appears to be a suitable alternative or complementary to the TFT and TTEHT.

Testing Microshutter Arrays Using Commercial FPGA Hardware

NASA Technical Reports Server (NTRS)

Rapchun, David

2008-01-01

NASA is developing micro-shutter arrays for the Near Infrared Spectrometer (NIRSpec) instrument on the James Webb Space Telescope (JWST). These micro-shutter arrays allow NIRspec to do Multi Object Spectroscopy, a key part of the mission. Each array consists of 62414 individual 100 x 200 micron shutters. These shutters are magnetically opened and held electrostatically. Individual shutters are then programmatically closed using a simple row/column addressing technique. A common approach to provide these data/clock patterns is to use a Field Programmable Gate Array (FPGA). Such devices require complex VHSIC Hardware Description Language (VHDL) programming and custom electronic hardware. Due to JWST's rapid schedule on the development of the micro-shutters, rapid changes were required to the FPGA code to facilitate new approaches being discovered to optimize the array performance. Such rapid changes simply could not be made using conventional VHDL programming. Subsequently, National Instruments introduced an FPGA product that could be programmed through a Labview interface. Because Labview programming is considerably easier than VHDL programming, this method was adopted and brought success. The software/hardware allowed the rapid change the FPGA code and timely results of new micro-shutter array performance data. As a result, numerous labor hours and money to the project were conserved.

Robust frequency diversity based algorithm for clutter noise reduction of ultrasonic signals using multiple sub-spectrum phase coherence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gongzhang, R.; Xiao, B.; Lardner, T.

2014-02-18

This paper presents a robust frequency diversity based algorithm for clutter reduction in ultrasonic A-scan waveforms. The performance of conventional spectral-temporal techniques like Split Spectrum Processing (SSP) is highly dependent on the parameter selection, especially when the signal to noise ratio (SNR) is low. Although spatial beamforming offers noise reduction with less sensitivity to parameter variation, phased array techniques are not always available. The proposed algorithm first selects an ascending series of frequency bands. A signal is reconstructed for each selected band in which a defect is present when all frequency components are in uniform sign. Combining all reconstructed signalsmore » through averaging gives a probability profile of potential defect position. To facilitate data collection and validate the proposed algorithm, Full Matrix Capture is applied on the austenitic steel and high nickel alloy (HNA) samples with 5MHz transducer arrays. When processing A-scan signals with unrefined parameters, the proposed algorithm enhances SNR by 20dB for both samples and consequently, defects are more visible in B-scan images created from the large amount of A-scan traces. Importantly, the proposed algorithm is considered robust, while SSP is shown to fail on the austenitic steel data and achieves less SNR enhancement on the HNA data.« less

Test Structures For Bumpy Integrated Circuits

NASA Technical Reports Server (NTRS)

Buehler, Martin G.; Sayah, Hoshyar R.

1989-01-01

Cross-bridge resistors added to comb and serpentine patterns. Improved combination of test structures built into integrated circuit used to evaluate design rules, fabrication processes, and quality of interconnections. Consist of meshing serpentines and combs, and cross bridge. Structures used to make electrical measurements revealing defects in design or fabrication. Combination of test structures includes three comb arrays, two serpentine arrays, and cross bridge. Made of aluminum or polycrystalline silicon, depending on material in integrated-circuit layers evaluated. Aluminum combs and serpentine arrays deposited over steps made by polycrystalline silicon and diffusion layers, while polycrystalline silicon versions of these structures used to cross over steps made by thick oxide layer.

High density pixel array

NASA Technical Reports Server (NTRS)

McFall, James Earl (Inventor); Wiener-Avnear, Eliezer (Inventor)

2004-01-01

A pixel array device is fabricated by a laser micro-milling method under strict process control conditions. The device has an array of pixels bonded together with an adhesive filling the grooves between adjacent pixels. The array is fabricated by moving a substrate relative to a laser beam of predetermined intensity at a controlled, constant velocity along a predetermined path defining a set of grooves between adjacent pixels so that a predetermined laser flux per unit area is applied to the material, and repeating the movement for a plurality of passes of the laser beam until the grooves are ablated to a desired depth. The substrate is of an ultrasonic transducer material in one example for fabrication of a 2D ultrasonic phase array transducer. A substrate of phosphor material is used to fabricate an X-ray focal plane array detector.

Micro-machined high-frequency (80 MHz) PZT thick film linear arrays.

PubMed

Zhou, Qifa; Wu, Dawei; Liu, Changgeng; Zhu, Benpeng; Djuth, Frank; Shung, K

2010-10-01

This paper presents the development of a micromachined high-frequency linear array using PZT piezoelectric thick films. The linear array has 32 elements with an element width of 24 μm and an element length of 4 mm. Array elements were fabricated by deep reactive ion etching of PZT thick films, which were prepared from spin-coating of PZT sol-gel composite. Detailed fabrication processes, especially PZT thick film etching conditions and a novel transferring-and-etching method, are presented and discussed. Array designs were evaluated by simulation. Experimental measurements show that the array had a center frequency of 80 MHz and a fractional bandwidth (-6 dB) of 60%. An insertion loss of -41 dB and adjacent element crosstalk of -21 dB were found at the center frequency.

A discrete element model for damage and fracture of geomaterials under fatigue loading

NASA Astrophysics Data System (ADS)

Gao, Xiaofeng; Koval, Georg; Chazallon, Cyrille

2017-06-01

Failure processes in geomaterials (concrete, asphalt concrete, masonry, etc.) under fatigue loading (repeated moving loads, cycles of temperature, etc.) are responsible for most of the dysfunctions in pavements, brick structures, etc. In the beginning of the lifetime of a structure, the material presents only inner defects (micro cracks, voids, etc.). Due to the effect of the cyclic loading, these small defects tend to grow in size and quantity which damage the material, reducing its stiffness. With a relatively high number of cycles, these growing micro cracks become large cracks, which characterizes the fracture behavior. From a theoretical point of view, both mechanisms are treated differently. Fracture is usually described locally, with the propagation of cracks defined by the energy release rate at the crack tip; damage is usually associated to non-local approaches. In the present work, damage and fracture mechanics are combined in a local discrete element approach.

Large-area one-step assembly of three-dimensional porous metal micro/nanocages by ethanol-assisted femtosecond laser irradiation for enhanced antireflection and hydrophobicity.

PubMed

Li, Guoqiang; Li, Jiawen; Zhang, Chenchu; Hu, Yanlei; Li, Xiaohong; Chu, Jiaru; Huang, Wenhao; Wu, Dong

2015-01-14

The capability to realize 2D-3D controllable metallic micro/nanostructures is of key importance for various fields such as plasmonics, electronics, bioscience, and chemistry due to unique properties such as electromagnetic field enhancement, catalysis, photoemission, and conductivity. However, most of the present techniques are limited to low-dimension (1D-2D), small area, or single function. Here we report the assembly of self-organized three-dimensional (3D) porous metal micro/nanocages arrays on nickel surface by ethanol-assisted femtosecond laser irradiation. The underlying formation mechanism was investigated by a series of femtosecond laser irradiation under exposure time from 5 to 30 ms. We also demonstrate the ability to control the size of micro/nanocage arrays from 0.8 to 2 μm by different laser pulse energy. This method features rapidness (∼10 min), simplicity (one-step process), and ease of large-area (4 cm(2) or more) fabrication. The 3D cagelike micro/nanostructures exhibit not only improved antireflection from 80% to 7% but also enhanced hydrophobicity from 98.5° to 142° without surface modification. This simple technique for 3D large-area controllable metal microstructures will find great potential applications in optoelectronics, physics, and chemistry.

Cathodoluminescence microscopy and spectroscopy of micro- and nanodiamonds: an implication for laboratory astrophysics.

PubMed

Gucsik, Arnold; Nishido, Hirotsugu; Ninagawa, Kiyotaka; Ott, Ulrich; Tsuchiyama, Akira; Kayama, Masahiro; Simonia, Irakli; Boudou, Jean-Paul

2012-12-01

Color centers in selected micro- and nanodiamond samples were investigated by cathodoluminescence (CL) microscopy and spectroscopy at 298 K [room temperature (RT)] and 77 K [liquid-nitrogen temperature (LNT)] to assess the value of the technique for astrophysics. Nanodiamonds from meteorites were compared with synthetic diamonds made with different processes involving distinct synthesis mechanisms (chemical vapor deposition, static high pressure high temperature, detonation). A CL emission peak centered at around 540 nm at 77 K was observed in almost all of the selected diamond samples and is assigned to the dislocation defect with nitrogen atoms. Additional peaks were identified at 387 and 452 nm, which are related to the vacancy defect. In general, peak intensity at LNT at the samples was increased in comparison to RT. The results indicate a clear temperature-dependence of the spectroscopic properties of diamond. This suggests the method is a useful tool in laboratory astrophysics.

Review on TAS-102 development and its use for metastatic colorectal cancer.

PubMed

Mota, Jose Mauricio; Fonseca, Leonardo G; Braghiroli, Maria Ignez; Hoff, Paulo M

2016-08-01

TAS-102 is the combination of trifluridine (TFT) with tipiracil (TPI) in a 1:0.5 molar ratio. TFT is a fluoropyrimidine that retains cytotoxic activity in 5-fluorouracil resistant cell lines. Due to TFT short half-life, early clinical development was discouraging. Thereafter, TFT was shown to be promptly degraded by thymidine phosphorylase, also known as platelet-derived endothelial cell growth factor, a pro-angiogenic protein and a poor prognosis marker in colorectal cancer. TPI is a specific antagonist of thymidine phosphorylase and led to an increase in TFT serum levels when both agents are combined. Moreover, TPI is a potential anti-angiogenic molecule and could exert antitumor actions per se. TAS-102 was tested in several Phase I studies published in the early 21st century. The best regimen was settled as 70mg/m(2)/day, q12h, orally given at days 1-5 and days 8-13, each 28days. Recently, the first Phase III trial evaluating TAS-102 in refractory colorectal cancer patients was published. The RECOURSE trial demonstrated a survival advantage of the agent over supportive care, and definitely established TAS-102 as a novel strategy in the current armamentarium against colorectal cancer. Here we review the preclinical data regarding TFT and TPI that led to the development of TAS-102, and the set of clinical data that ultimately proved that TAS-102 improved outcomes in colorectal cancer patients. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Polymer-stabilized liquid crystalline topological defect network for micro-pixelated optical devices

NASA Astrophysics Data System (ADS)

Araoka, Fumito; Le, Khoa V.; Fujii, Shuji; Orihara, Hiroshi; Sasaki, Yuji

2018-02-01

Spatially and temporally controlled topological defects in nematic liquid crystals (NLCs) are promising for its potential in optical applications. Utilization of self-organization is a key to fabricate complex micro- and nano-structures which are often difficult to obtain by conventional lithographic tools. Using photo-polymerization technique, here we show a polymer-stabilized NLC having a micro-pixelated structure of regularly ordered umbilical defects which are induced by an electric field. Due to the formation of polymer network, the self-organized pattern is kept stable without deterioration. Moreover, the polymer network allows to template other LCs whose optical properties can be tuned with external stimuli such as temperature and electric fields.

Active-Matrix Organic Light Emission Diode Pixel Circuit for Suppressing and Compensating for the Threshold Voltage Degradation of Hydrogenated Amorphous Silicon Thin Film Transistors

NASA Astrophysics Data System (ADS)

Shin, Hee-Sun; Lee, Won-Kyu; Park, Sang-Guen; Kuk, Seung-Hee; Han, Min-Koo

2009-03-01

A new hydrogenated amorphous silicon (a-Si:H) thin film transistor (TFT) pixel circuit for active-matrix organic light emission diodes (AM-OLEDs), which significantly compensates the OLED current degradation by memorizing the threshold voltage of driving TFT and suppresses the threshold voltage shift of a-Si:H TFTs by negative bias annealing, is proposed and fabricated. During the first half of each frame, the driving TFT of the proposed pixel circuit supplies current to the OLED, which is determined by modified data voltage in the compensation scheme. The proposed pixel circuit was able to compensate the threshold voltage shift of the driving TFT as well as the OLED. During the remaining half of each frame, the proposed pixel circuit induces the recovery of the threshold voltage degradation of a-Si:H TFTs owing to the negative bias annealing. The experimental results show that the proposed pixel circuit was able to successfully compensate for the OLED current degradation and suppress the threshold voltage degradation of the driving TFT.

Free-floating epithelial micro-tissue arrays: a low cost and versatile technique.

PubMed

Flood, P; Alvarez, L; Reynaud, E G

2016-10-11

Three-dimensional (3D) tissue models are invaluable tools that can closely reflect the in vivo physiological environment. However, they are usually difficult to develop, have a low throughput and are often costly; limiting their utility to most laboratories. The recent availability of inexpensive additive manufacturing printers and open source 3D design software offers us the possibility to easily create affordable 3D cell culture platforms. To demonstrate this, we established a simple, inexpensive and robust method for producing arrays of free-floating epithelial micro-tissues. Using a combination of 3D computer aided design and 3D printing, hydrogel micro-moulding and collagen cell encapsulation we engineered microenvironments that consistently direct the growth of micro-tissue arrays. We described the adaptability of this technique by testing several immortalised epithelial cell lines (MDCK, A549, Caco-2) and by generating branching morphology and micron to millimetre scaled micro-tissues. We established by fluorescence and electron microscopy that micro-tissues are polarised, have cell type specific differentiated phenotypes and regain native in vivo tissue qualities. Finally, using Salmonella typhimurium we show micro-tissues display a more physiologically relevant infection response compared to epithelial monolayers grown on permeable filter supports. In summary, we have developed a robust and adaptable technique for producing arrays of epithelial micro-tissues. This in vitro model has the potential to be a valuable tool for studying epithelial cell and tissue function/architecture in a physiologically relevant context.

Channel width dependence of electrical characteristics of a-Si:H TFTs under bending stresses

NASA Astrophysics Data System (ADS)

Oh, Hyungon; Cho, Kyoungah; Kim, Sangsig

2017-04-01

In this study, we investigate the electrical characteristics of bendable a-Si:H thin-film transistors (TFTs) with various channel widths as a function of bending stress. Compared with a narrower channel TFT, a wider channel TFT exhibits a stable performance even at a bending strain of 1.3%. Our stress and strain distribution analysis reveals an inverse relationship between the channel width and the channel stress. As the channel width widens from 8 to 50 μm, the stress experienced by the middle channel region decreases from 545 to 277 MPa. Moreover, a 50 μm-channel-width TFT operates stably even after a 15 000 bending cycle while the 8 μm-channel-width TFT fails to operate after a 2000 bending cycle.

Gold ultra-microelectrode arrays: application to the steady-state voltammetry of hydroxide ion in aqueous solution.

PubMed

Ordeig, Olga; Banks, Craig E; Davies, Trevor J; del Campo, F Javier; Muñoz, Francesc Xavier; Compton, Richard G

2006-05-01

Gold ultra-microelectrode arrays are used to explore the electrochemical oxidation of hydroxide ions and are shown to be analytical useful. Two types of ultra-microelectrode arrays are used; the first consist of 256 individual electrodes of 5 microm in radius, 170 of which are electrochemically active in a cubic arrangement which are separated from their nearest neighbour by a distance of 100 microm. The second array compromises 2597 electrodes of 2.5 microm in radius and of which 1550 of which are electrochemically active in a hexagonal arrangement separated by the nearest neighbour by 55 microm. Well defined voltammetric waves are found with peak currents proportional to the concentration of hydroxide ions in the range 50 microM to 1 mM. Detection limits of 20 microM using the 170 ultra-microelectrode and 10 microM with the 1550 ultra-microelectrode array are shown to be possible but with a higher sensitivity of 4 mA M(-1) observed using the 1550 ultra-microelectrode array compared to 1.2 mA M(-1) with the 170 ultra-microelectrode array.

Quantification of the effectiveness of handheld equipment for ground verification of detected rail internal defects.

DOT National Transportation Integrated Search

2014-04-01

The objective of this project was to quantify the effectiveness of the rail inspection ground verification process. More specifically, : the project focused on comparing the effectiveness of conventional versus phased array probes to manually detect ...

DSA process window expansion with novel DSA track hardware

NASA Astrophysics Data System (ADS)

Harumoto, Masahiko; Stokes, Harold; Tanaka, Yuji; Kaneyama, Koji; Pieczulewski, Chalres; Asai, Masaya; Argoud, Maxime; Servin, Isabelle; Chamiot-Maitral, Gaëlle; Claveau, Guillaume; Tiron, Raluca; Cayrefourcq, Ian

2017-03-01

PS-b-PMMA block copolymer is a well-known DSA material, and there are many DSA patterning methods that make effective the use of such 1st generation materials. Consequently, this variety of patterning methods opens a wide array of possibilities for DSA application[1-4]. Last year, during the inaugural International DSA Symposium, researchers and lithographers concurred on common key issues for DSA patterning methods such as: defect density, LWR, placement error, etc. Defect density was specifically expressed as the biggest obstacle for new processes. Coat-Develop track systems contribute to the DSA pattern fabrication and also influence the DSA pattern performances[4]. In this study, defectivity was investigated using an atmosphere-controlled chamber on the SOKUDO DUO track. As an initial step for expanding the DSA process window, fingerprint patterns were used for various atmospheric conditions during DSA self-assembly annealing. In this study, we will demonstrate an improved DSA process window, and then we will discuss the mechanism for this atmospheric effect.

Tuning the ferromagnetic resonance frequency of soft magnetic film by patterned permalloy micro-stripes with stripe-domain

NASA Astrophysics Data System (ADS)

Pan, Lining; Xie, Hongkang; Cheng, Xiaohong; Zhao, Chenbo; Feng, Hongmei; Cao, Derang; Wang, Jianbo; Liu, Qingfang

2018-07-01

Periodic micro-stripes arrays with stripe domains structures upon continuous permalloy (Py) film were fabricated by sputtering, photolithography and ion beam etching technology. These samples display in-plane magnetic anisotropy, and stripe domains structure is observed by the magnetic force microscopy (MFM) in the area of the micro-stripes. The periodic micro-stripes show an effective impact on static and dynamic magnetic properties of Py continuous film. In the case of dynamic magnetic properties, the resonance frequency fr of these samples can be tuned by periodic micro-stripes arrays. Compared to continuous film with resonance frequency fr of 0.64 GHz, the fr of composite structures can be tuned by the separation gap of periodic micro-stripes arrays from 0.8 GHz to 2.3 GHz at zero-field. At the same time, the fr could be also tuned by rotating the samples within the plane. This attributes to the competition of shape anisotropy induced by micro-stripes and the dynamic anisotropy originating by stripe domains structure.

Hygrothermomechanical evaluation of transverse filament tape epoxy/polyester fiberglass composites

NASA Technical Reports Server (NTRS)

Lark, R. F.; Chamis, C. C.

1984-01-01

Transverse filament tape (TFT) fiberglass/epoxy and TFT polyester composites intended for low cost wind turbine blade fabrication have been subjected to static and cyclic load behavior tests whose results are presently evaluated on the basis of an integrated hygrothermomechanical response theory. Laminate testing employed simulated filament winding procedures. The results obtained show that the predicted hygrothermomechanical environmental effects on TFT composites are in good agreement with measured data for various properties, including fatigue at different R-ratio values.

The two-dimensional hybrid surface plasma micro-cavity

NASA Astrophysics Data System (ADS)

Kai, Tong; Mei-yu, Wang; Fu-cheng, Wang; Jia, Guo

2018-07-01

A hybrid surface plasma micro-cavity structure with a defect cavity is formed based on the two-dimensional surface plasmon resonance photonic crystal waveguide structure. A cell defect is introduced in the centre of the photonic crystal layer to build the hybrid surface plasma micro-cavity structure. This work is numerical based on the finite-difference time-domain method. The photon energy is confined to the micro-cavity and the photon energy is strongest at the interface between the insulating layer and the metal layer. The micro-cavity structure has a very small mode volume of sub-wavelength scale in the 1550 nm communication band. The value of Q/V is up to 7132.08 λ/n-3.

Effects of laser shock peening with contacting foil on micro laser texturing surface of Ti6Al4V

NASA Astrophysics Data System (ADS)

Dai, Fengze; Zhang, Zidong; Ren, Xudong; Lu, Jinzhong; Huang, Shu

2018-02-01

Ti6Al4V samples with micro-dimple arrays were subjected to laser shock peening in contact with foil (HCLSP). The surface roughness, micro-hardness, the residual stress distribution and the surface morphology of the micro-dimple arrays were studied to evaluate the effects of HCLSP. Moreover, the surface topography of the foils in contact was also analyzed. The gap existence between the foil and the to-be treated surface led the mechanism of HCLSP to be different compared to regular laser shock peening. The surface roughness reduction, the work-hardening effects, the compressive residual stress and the micro crack enclosure were achieved. A simplified ball-hitting-surface model was utilized to analyze the HCLSP impact. The model could well explain the experimental results. When treated by the HCLSP with H62 foil at the laser power density of 4.24 GW/cm2, the Ti6Al4V samples with micro-dimple arrays exhibit well surface topography and mechanical performance.

Highly effective field-effect mobility amorphous InGaZnO TFT mediated by directional silver nanowire arrays.

PubMed

Liu, Hung-Chuan; Lai, Yi-Chun; Lai, Chih-Chung; Wu, Bing-Shu; Zan, Hsiao-Wen; Yu, Peichen; Chueh, Yu-Lun; Tsai, Chuang-Chuang

2015-01-14

In this work, we demonstrate sputtered amorphous indium-gallium-zinc oxide thin-film transistors (a-IGZO TFTs) with a record high effective field-effect mobility of 174 cm(2)/V s by incorporating silver nanowire (AgNW) arrays to channel electron transport. Compared to the reference counterpart without nanowires, the over 5-fold enhancement in the effective field-effect mobility exhibits clear dependence on the orientation as well as the surface coverage ratio of silver nanowires. Detailed material and device analyses reveal that during the room-temperature IGZO sputtering indium and oxygen diffuse into the nanowire matrix while the nanowire morphology and good contact between IGZO and nanowires are maintained. The unchanged morphology and good interfacial contact lead to high mobility and air-ambient-stable characteristics up to 3 months. Neither hysteresis nor degraded bias stress reliability is observed. The proposed AgNW-mediated a-IGZO TFTs are promising for development of large-scale, flexible, transparent electronics.

Performance of s-192 (hg,cd)te arrays.

PubMed

Aldrich, N C; Beck, J D

1972-10-01

Very high performance (Hg,Cd)Te photoconductive detectors have been fabricated for use on the S-192 experiment, which is a multispectral scanner being built by Honeywell for the NASA Manned Space Center's Skylab. The S-192 will scan the earth from Skylab and record data in twelve near ir spectral bands and one long wavelength band. The near ir bands range from 0.4 micro to 2.35 micro. At 87 K with a 90 degrees FOV, we have consistently produced arrays with specific detectivities at 2.35 micro close to or greater than 8 x 10(11) cm Hz((1/2))/W and with detective time constants less than 1 microsec. These detectors demonstrate good uniformity in performance across an array. State-of-the-art fabrication techniques have been used to make detectors with good definition that are 5-10 micro thick with 25-micro spacing between elements.

A New Individually Addressable Micro-LED Array for Photogenetic Neural Stimulation.

PubMed

McGovern, B; Berlinguer Palmini, R; Grossman, N; Drakakis, E; Poher, V; Neil, M A A; Degenaar, P

2010-12-01

Here, we demonstrate the use of a micro light emitting diode (LED) array as a powerful tool for complex spatiotemporal control of photosensitized neurons. The array can generate arbitrary, 2-D, excitation patterns with millisecond and micrometer resolution. In particular, we describe an active matrix control address system to allow simultaneous control of 256 individual micro LEDs. We present the system optically integrated into a microscope environment and patch clamp electrophysiology. The results show that the emitters have sufficient radiance at the required wavelength to stimulate neurons expressing channelrhodopsin-2 (ChR2).

Visual Costs of the Inhomogeneity of Luminance and Contrast by Viewing LCD-TFT Screens Off-Axis.

PubMed

Ziefle, Martina; Groeger, Thomas; Sommer, Dietmar

2003-01-01

In this study the anisotropic characteristics of TFT-LCD (Thin-Film-Transistor-Liquid Crystal Display) screens were examined. Anisotropy occurs as the distribution of luminance and contrast changes over the screen surface due to different viewing angles. On the basis of detailed photometric measurements the detection performance in a visual reaction task was measured in different viewing conditions. Viewing angle (0 degrees, frontal view; 30 degrees, off-axis; 50 degrees, off-axis) as well as ambient lighting (a dark or illuminated room) were varied. Reaction times and accuracy of detection performance were recorded. Results showed TFT's anisotropy to be a crucial factor deteriorating performance. With an increasing viewing angle performance decreased. It is concluded that TFT's anisotropy is a limiting factor for overall suitability and usefulness of this new display technology.

Strikingly enhanced cooling performance for a micro-cooler using unique Cu nanowire array with high electrical conductivity and fast heat transfer behavior

NASA Astrophysics Data System (ADS)

Tan, Ming; Wang, Xiuzhen; Hao, Yanming; Deng, Yuan

2017-06-01

It was found that phonons/electrons are less scattered along (1 1 1)-preferred Cu nanowires than in ordinary structure films and that the interface of Cu nanowires electrode and thermoelectric materials are more compatible. Here highly ordered, high-crystal-quality, high-density Cu nanowire array was successfully fabricated by a magnetron sputtering method. The Cu nanowire array was successfully incorporated using mask-assisted deposition technology as electrodes for thin-film thermoelectric coolers, which would greatly improve electrical/thermal transport and enhance performance of micro-coolers. The cooling performance of the micro-cooler with Cu nanowire array electrode is over 200% higher than that of the cooler with ordinary film electrode.

Localized Defect Modes in a Two-Dimensional Array of Magnetic Nanodots

DTIC Science & Technology

2013-06-22

number of defects it is possible to obtain the information about the entire spin-wave spectrum of the array. Index Terms—Spin waves, magnonic crystal...multistability opens a way for the development of a novel type of artificial materials with tunable microwave properties – reconfigurable magnonic ...information about the entire spin-wave spectrum of the array. 15. SUBJECT TERMS Spin waves, magnonic crystal, magnetic dot, ferromagnetic resonance

Thermal decomposition behavior of nano/micro bimodal feedstock with different solids loading

NASA Astrophysics Data System (ADS)

Oh, Joo Won; Lee, Won Sik; Park, Seong Jin

2018-01-01

Debinding is one of the most critical processes for powder injection molding. The parts in debinding process are vulnerable to defect formation, and long processing time of debinding decreases production rate of whole process. In order to determine the optimal condition for debinding process, decomposition behavior of feedstock should be understood. Since nano powder affects the decomposition behavior of feedstock, nano powder effect needs to be investigated for nano/micro bimodal feedstock. In this research, nano powder effect on decomposition behavior of nano/micro bimodal feedstock has been studied. Bimodal powders were fabricated with different ratios of nano powder, and the critical solids loading of each powder was measured by torque rheometer. Three different feedstocks were fabricated for each powder depending on solids loading condition. Thermogravimetric analysis (TGA) experiment was carried out to analyze the thermal decomposition behavior of the feedstocks, and decomposition activation energy was calculated. The result indicated nano powder showed limited effect on feedstocks in lower solids loading condition than optimal range. Whereas, it highly influenced the decomposition behavior in optimal solids loading condition by causing polymer chain scission with high viscosity.

Advances in Testing Techniques for Digital Microfluidic Biochips

PubMed Central

Shukla, Vineeta; Hussin, Fawnizu Azmadi; Hamid, Nor Hisham; Zain Ali, Noohul Basheer

2017-01-01

With the advancement of digital microfluidics technology, applications such as on-chip DNA analysis, point of care diagnosis and automated drug discovery are common nowadays. The use of Digital Microfluidics Biochips (DMFBs) in disease assessment and recognition of target molecules had become popular during the past few years. The reliability of these DMFBs is crucial when they are used in various medical applications. Errors found in these biochips are mainly due to the defects developed during droplet manipulation, chip degradation and inaccuracies in the bio-assay experiments. The recently proposed Micro-electrode-dot Array (MEDA)-based DMFBs involve both fluidic and electronic domains in the micro-electrode cell. Thus, the testing techniques for these biochips should be revised in order to ensure proper functionality. This paper describes recent advances in the testing technologies for digital microfluidics biochips, which would serve as a useful platform for developing revised/new testing techniques for MEDA-based biochips. Therefore, the relevancy of these techniques with respect to testing of MEDA-based biochips is analyzed in order to exploit the full potential of these biochips. PMID:28749411

Advances in Testing Techniques for Digital Microfluidic Biochips.

PubMed

Shukla, Vineeta; Hussin, Fawnizu Azmadi; Hamid, Nor Hisham; Zain Ali, Noohul Basheer

2017-07-27

With the advancement of digital microfluidics technology, applications such as on-chip DNA analysis, point of care diagnosis and automated drug discovery are common nowadays. The use of Digital Microfluidics Biochips (DMFBs) in disease assessment and recognition of target molecules had become popular during the past few years. The reliability of these DMFBs is crucial when they are used in various medical applications. Errors found in these biochips are mainly due to the defects developed during droplet manipulation, chip degradation and inaccuracies in the bio-assay experiments. The recently proposed Micro-electrode-dot Array (MEDA)-based DMFBs involve both fluidic and electronic domains in the micro-electrode cell. Thus, the testing techniques for these biochips should be revised in order to ensure proper functionality. This paper describes recent advances in the testing technologies for digital microfluidics biochips, which would serve as a useful platform for developing revised/new testing techniques for MEDA-based biochips. Therefore, the relevancy of these techniques with respect to testing of MEDA-based biochips is analyzed in order to exploit the full potential of these biochips.

A novel AFM-based 5-axis nanoscale machine tool for fabrication of nanostructures on a micro ball

NASA Astrophysics Data System (ADS)

Geng, Yanquan; Wang, Yuzhang; Yan, Yongda; Zhao, Xuesen

2017-11-01

This paper presents a novel atomic force microscopy (AFM)-based 5-axis nanoscale machine tool developed to fabricate nanostructures on different annuli of the micro ball. Different nanostructures can be obtained by combining the scratching trajectory of the AFM tip with the movement of the high precision air-bearing spindle. The center of the micro ball is aligned to be coincided with the gyration center of the high precision to guarantee the machining process during the rotating of the air-bearing spindle. Processing on different annuli of the micro ball is achieved by controlling the distance between the center of the micro ball and the rotation center of the AFM head. Nanostructures including square cavities, circular cavities, triangular cavities, and an annular nanochannel are machined successfully on the three different circumferences of a micro ball with a diameter of 1500 μm. Moreover, the influences of the error motions of the high precision air-bearing spindle and the eccentric between the micro ball and the gyration center of the high precision air-bearing spindle on the processing position error on the micro ball are also investigated. This proposed machining method has the potential to prepare the inertial confinement fusion target with the expected dimension defects, which would advance the application of the AFM tip-based nanomachining approach.

Numerical analysis of a main crack interactions with micro-defects/inhomogeneities using two-scale generalized/extended finite element method

NASA Astrophysics Data System (ADS)

Malekan, Mohammad; Barros, Felício B.

2017-12-01

Generalized or extended finite element method (G/XFEM) models the crack by enriching functions of partition of unity type with discontinuous functions that represent well the physical behavior of the problem. However, this enrichment functions are not available for all problem types. Thus, one can use numerically-built (global-local) enrichment functions to have a better approximate procedure. This paper investigates the effects of micro-defects/inhomogeneities on a main crack behavior by modeling the micro-defects/inhomogeneities in the local problem using a two-scale G/XFEM. The global-local enrichment functions are influenced by the micro-defects/inhomogeneities from the local problem and thus change the approximate solution of the global problem with the main crack. This approach is presented in detail by solving three different linear elastic fracture mechanics problems for different cases: two plane stress and a Reissner-Mindlin plate problems. The numerical results obtained with the two-scale G/XFEM are compared with the reference solutions from the analytical, numerical solution using standard G/XFEM method and ABAQUS as well, and from the literature.

Investigations on the micro-scale surface interactions at the tool and workpiece interface in micro-manufacturing of bipolar plates for proton exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Peker, Mevlut Fatih

Micro-forming studies have been more attractive in recent years because of miniaturization trend. One of the promising metal forming processes, micro-stamping, provides durability, strength, surface finish, and low cost for metal products. Hence, it is considered a prominent method for fabricating bipolar plates (BPP) with micro-channel arrays on large metallic surfaces to be used in Proton Exchange Membrane Fuel Cells (PEMFC). Major concerns in micro-stamping of high volume BPPs are surface interactions between micro-stamping dies and blank metal plates, and tribological changes. These concerns play a critical role in determining the surface quality, channel formation, and dimensional precision of bipolar plates. The surface quality of BPP is highly dependent on the micro-stamping die surface, and process conditions due to large ratios of surface area to volume (size effect) that cause an increased level of friction and wear issues at the contact interface. Due to the high volume and fast production rates, BPP surface characteristics such as surface roughness, hardness, and stiffness may change because of repeated interactions between tool (micro-forming die) and workpiece (sheet blank of interest). Since the surface characteristics of BPPs have a strong effect on corrosion and contact resistance of bipolar plates, and consequently overall fuel cell performance, evolution of surface characteristics at the tool and workpiece should be monitored, controlled, and kept in acceptable ranges throughout the long production cycles to maintain the surface quality. Compared to macro-forming operations, tribological changes in micro-forming process are bigger challenges due to their dominance and criticality. Therefore, tribological size effect should be considered for better understanding of tribological changes in micro-scale. The integrity of process simulation to the experiments, on the other hand, is essential. This study describes an approach that aims to investigate the surface topography changes during long-run micro-stamping of BPPs, and establish relationships between surface roughness--corrosion resistance and surface roughness-contact resistance characteristics of BPPs. Formability levels of formed BPPs and repeatability characteristics of the process were investigated. In addition, blank thickness changes, von-Mises stress, plastic strain levels and distributions of micro-stamping process were determined via finite element analysis (FEA). Test results revealed that the surface roughness change for the stamping dies and BPPs was unsteady (no trend) due to the continuous change of surface topography (i.e. asperity deformation). Sub-micron range local plastic deformations on stamping dies led to surface topography changes on BPP in long-run manufacturing case. As surface defects trigger corrosion, the correlation between surface roughness and corrosion resistance of BPPs was found to be direct. Increasing number of surface irregularities (asperities) lowered contact surface area that resulted in increased contact resistance. ZrN coated BPPs, on the other hand, did not change surface roughness, however; it improved the protection of BPPs against corrosion significantly. In addition, ZrN coating increased the conductivity of BPPs and reduced the contact resistance between BPP and gas diffusion layer (GDL), at certain extent. As dimensional stability and repeatability was confirmed in forming of both uncoated and coated BPPs during the long run manufacturing, different formability levels were achieved for coated and uncoated samples. Lower channel height values were obtained for coated plates because of the different surface hardness of uncoated and coated plates. In tribological size effect part of study, micro stamping experiments using three different dies with distinct channel height values at different stamping force levels were performed. It was concluded that decrease in forming die dimensions led to increase in coefficient of friction as previously reported by other researchers as one of the consequences of tribological size effect. On the other hand, coefficient of friction values were not affected by the force levels used in the experiments and simulations, whereas plastic strain, equivalent stress, and formability levels were increased with increasing stamping force, as expected. In essence, this study proposed a methodology to investigate the long-run manufacturing effects on dimensional stability and surface characteristics of micro-stamped sheets. It also correlates these parameters to fuel cell performance measures such as interfacial contact and corrosion resistance.

The system analysis of light field information collection based on the light field imaging

NASA Astrophysics Data System (ADS)

Wang, Ye; Li, Wenhua; Hao, Chenyang

2016-10-01

Augmented reality(AR) technology is becoming the study focus, and the AR effect of the light field imaging makes the research of light field camera attractive. The micro array structure was adopted in most light field information acquisition system(LFIAS) since emergence of light field camera, micro lens array(MLA) and micro pinhole array(MPA) system mainly included. It is reviewed in this paper the structure of the LFIAS that the Light field camera commonly used in recent years. LFIAS has been analyzed based on the theory of geometrical optics. Meanwhile, this paper presents a novel LFIAS, plane grating system, we call it "micro aperture array(MAA." And the LFIAS are analyzed based on the knowledge of information optics; This paper proves that there is a little difference in the multiple image produced by the plane grating system. And the plane grating system can collect and record the amplitude and phase information of the field light.

Analysis of mutations in oral poliovirus vaccine by hybridization with generic oligonucleotide microchips.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Proudnikov, D.; Kirillov, E.; Chumakov, K.

2000-01-01

This paper describes use of a new technology of hybridization with a micro-array of immobilized oligonucleotides for detection and quantification of neurovirulent mutants in Oral Poliovirus Vaccine (OPV). We used a micro-array consisting of three-dimensional gel-elements containing all possible hexamers (total of 4096 probes). Hybridization of fluorescently labelled viral cDNA samples with such microchips resulted in a pattern of spots that was registered and quantified by a computer-linked CCD camera, so that the sequence of the original cDNA could be deduced. The method could reliably identify single point mutations, since each of them affected fluorescence intensity of 12 micro-array elements.more » Micro-array hybridization of DNA mixtures with varying contents of point mutants demonstrated that the method can detect as little as 10% of revertants in a population of vaccine virus. This new technology should be useful for quality control of live viral vaccines, as well as for other applications requiring identification and quantification of point mutations.« less

Discussion on the solar concentrating thermoelectric generation using micro-channel heat pipe array

NASA Astrophysics Data System (ADS)

Li, Guiqiang; Feng, Wei; Jin, Yi; Chen, Xiao; Ji, Jie

2017-11-01

Heat pipe is a high efficient tool in solar energy applications. In this paper, a novel solar concentrating thermoelectric generation using micro-channel heat pipe array (STEG-MCHP) was presented. The flat-plate micro-channel heat pipe array not only has a higher heat transfer performance than the common heat pipe, but also can be placed on the surface of TEG closely, which can further reduce the thermal resistance between the heat pipe and the TEG. A preliminary comparison experiment was also conducted to indicate the advantages of the STEG-MCHP. The optimization based on the model verified by the experiment was demonstrated, and the concentration ratio and selective absorbing coating area were also discussed. In addition, the cost analysis was also performed to compare between the STEG-MCHP and the common solar concentrating TEGs in series. The outcome showed that the solar concentrating thermoelectric generation using micro-channel heat pipe array has the higher electrical efficiency and lower cost, which may provide a suitable way for solar TEG applications.

Toward Adequate Operation of Amorphous Oxide Thin-Film Transistors for Low-Concentration Gas Detection.

PubMed

Kim, Kyung Su; Ahn, Cheol Hyoun; Jung, Sung Hyeon; Cho, Sung Woon; Cho, Hyung Koun

2018-03-28

We suggest the use of a thin-film transistor (TFT) composed of amorphous InGaZnO (a-IGZO) as a channel and a sensing layer for low-concentration NO 2 gas detection. Although amorphous oxide layers have a restricted surface area when reacting with NO 2 gas, such TFT sensors have incomparable advantages in the aspects of electrical stability, large-scale uniformity, and the possibility of miniaturization. The a-IGZO thin films do not possess typical reactive sites and grain boundaries, so that the variation in drain current of the TFTs strictly originates from oxidation reaction between channel surface and NO 2 gas. Especially, the sensing data obtained from the variation rate of drain current makes it possible to monitor efficiently and quickly the variation of the NO 2 concentration. Interestingly, we found that enhancement-mode TFT (EM-TFT) allows discrimination of the drain current variation rate at NO 2 concentrations ≤10 ppm, whereas a depletion-mode TFT is adequate for discriminating NO 2 concentrations ≥10 ppm. This discrepancy is attributed to the ratio of charge carriers contributing to gas capture with respect to total carriers. This capacity for the excellent detection of low-concentration NO 2 gas can be realized through (i) three-terminal TFT gas sensors using amorphous oxide, (ii) measurement of the drain current variation rate for high selectivity, and (iii) an EM mode driven by tuning the electrical conductivity of channel layers.

Thin film transistor performance of amorphous indium–zinc oxide semiconductor thin film prepared by ultraviolet photoassisted sol–gel processing

NASA Astrophysics Data System (ADS)

Kodzasa, Takehito; Nobeshima, Taiki; Kuribara, Kazunori; Yoshida, Manabu

2018-05-01

We have fabricated an amorphous indium–zinc oxide (IZO, In/Zn = 3/1) semiconductor thin-film transistor (AOS-TFT) by the sol–gel technique using ultraviolet (UV) photoirradiation and post-treatment in high-pressure O2 at 200 °C. The obtained TFT showed a hole carrier mobility of 0.02 cm2 V‑1 s‑1 and an on/off current ratio of 106. UV photoirradiation leads to the decomposition of the organic agents and hydroxide group in the IZO gel film. Furthermore, the post-treatment annealing at a high O2 pressure of more than 0.6 MPa leads to the filling of the oxygen vacancies in a poor metal–oxygen network in the IZO film.

Enhanced stability against bias-stress of metal-oxide thin film transistors deposited at elevated temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fakhri, M.; Goerrn, P.; Riedl, T.

2011-09-19

Transparent zinc-tin-oxide (ZTO) thin film transistors (TFTs) have been prepared by DC magnetron sputtering. Compared to reference devices with a channel deposited at room temperature and subsequently annealing at 400 deg. C, a substantially enhanced stability against bias stress is evidenced for devices with in-situ substrate heating during deposition (400 deg. C). A reduced density of sub-gap defect states in TFT channels prepared with in-situ substrate heating is found. Concomitantly, a reduced sensitivity to the adsorption of ambient gases is evidenced for the in-situ heated devices. This finding is of particular importance for an application as driver electronics for organicmore » light emitting diode displays.« less

The development of a multichannel electrode array for retinal prostheses.

PubMed

Terasawa, Yasuo; Tashiro, Hiroyuki; Uehara, Akihiro; Saitoh, Tohru; Ozawa, Motoki; Tokuda, Takashi; Ohta, Jun

2006-01-01

The development of a multielectrode array is the key issue for retinal prostheses. We developed a 10 x 10 platinum electrode array that consists of an 8-microm polyimide layer sandwiched between 5-microm polymonochloro-para-xylylene (parylene-C) layers. Each electrode was formed as a 30-microm-high bump by Pt/Au double-layer electroplating. We estimated the charge delivery capability (CDC) of the electrode by measuring the CDCs of two-channel electrode arrays. The dimensions of each electrode of the two-channel array were the same as those of each electrode formed on the 10 x 10 array. The results suggest that for cathodic-first (CF) pulses, 80% of electrodes surpassed our development target of 318 microC/cm2, which corresponds to the charge density of pulses of 500 micros duration and 200 microA amplitude for a 200-microm-diameter planar electrode.

Remarkably high mobility ultra-thin-film metal-oxide transistor with strongly overlapped orbitals

NASA Astrophysics Data System (ADS)

Wei Shih, Chen; Chin, Albert; Fu Lu, Chun; Fang Su, Wei

2016-01-01

High mobility channel thin-film-transistor (TFT) is crucial for both display and future generation integrated circuit. We report a new metal-oxide TFT that has an ultra-thin 4.5 nm SnO2 thickness for both active channel and source-drain regions, very high 147 cm2/Vs field-effect mobility, high ION/IOFF of 2.3 × 107, small 110 mV/dec sub-threshold slope, and a low VD of 2.5 V for low power operation. This mobility is already better than chemical-vapor-deposition grown multi-layers MoS2 TFT. From first principle quantum-mechanical calculation, the high mobility TFT is due to strongly overlapped orbitals.

Remarkably high mobility ultra-thin-film metal-oxide transistor with strongly overlapped orbitals

PubMed Central

Wei Shih, Chen; Chin, Albert; Fu Lu, Chun; Fang Su, Wei

2016-01-01

High mobility channel thin-film-transistor (TFT) is crucial for both display and future generation integrated circuit. We report a new metal-oxide TFT that has an ultra-thin 4.5 nm SnO2 thickness for both active channel and source-drain regions, very high 147 cm2/Vs field-effect mobility, high ION/IOFF of 2.3 × 107, small 110 mV/dec sub-threshold slope, and a low VD of 2.5 V for low power operation. This mobility is already better than chemical-vapor-deposition grown multi-layers MoS2 TFT. From first principle quantum-mechanical calculation, the high mobility TFT is due to strongly overlapped orbitals. PMID:26744240

Biomechanical Characterization of Cardiomyocyte Using PDMS Pillar with Microgrooves

PubMed Central

Oyunbaatar, Nomin-Erdene; Lee, Deok-Hyu; Patil, Swati J.; Kim, Eung-Sam; Lee, Dong-Weon

2016-01-01

This paper describes the surface-patterned polydimethylsiloxane (PDMS) pillar arrays for enhancing cell alignment and contraction force in cardiomyocytes. The PDMS micropillar (μpillar) arrays with microgrooves (μgrooves) were fabricated using a unique micro-mold made using SU-8 double layer processes. The spring constant of the μpillar arrays was experimentally confirmed using atomic force microscopy (AFM). After culturing cardiac cells on the two different types of μpillar arrays, with and without grooves on the top of μpillar, the characteristics of the cardiomyocytes were analyzed using a custom-made image analysis system. The alignment of the cardiomyocytes on the μgrooves of the μpillars was clearly observed using a DAPI staining process. The mechanical force generated by the contraction force of the cardiomyocytes was derived from the displacement of the μpillar arrays. The contraction force of the cardiomyocytes aligned on the μgrooves was 20% higher than that of the μpillar arrays without μgrooves. The experimental results prove that applied geometrical stimulus is an effective method for aligning and improving the contraction force of cardiomyocytes. PMID:27517924

Heat resistive dielectric multi-layer micro-mirror array in epitaxial lateral overgrowth gallium nitride.

PubMed

Huang, Chen-Yang; Ku, Hao-Min; Liao, Wei-Tsai; Chao, Chu-Li; Tsay, Jenq-Dar; Chao, Shiuh

2009-03-30

Ta2O5 / SiO2 dielectric multi-layer micro-mirror array (MMA) with 3mm mirror size and 6mm array period was fabricated on c-plane sapphire substrate. The MMA was subjected to 1200 degrees C high temperature annealing and remained intact with high reflectance in contrast to the continuous multi-layer for which the layers have undergone severe damage by 1200 degrees C annealing. Epitaxial lateral overgrowth (ELO) of gallium nitride (GaN) was applied to the MMA that was deposited on both sapphire and sapphire with 2:56 mm GaN template. The MMA was fully embedded in the ELO GaN and remained intact. The result implies that our MMA is compatible to the high temperature growth environment of GaN and the MMA could be incorporated into the structure of the micro-LED array as a one to one micro backlight reflector, or as the patterned structure on the large area LED for controlling the output light.

Analysis of the enamel hypoplasia using micro-CT scanner versus classical method.

PubMed

Marchewka, Justyna; Skrzat, Janusz; Wróbel, Andrzej

2014-01-01

This article demonstrates the use of micro-CT scanning of the teeth surface for recognizing and evaluating severity of the enamel hypoplasia. To test capabilities of the microtomography versus classical method of evaluation hypoplastic defects of the enamel we selected two human teeth (C, M(2)) showing different types of enamel hypoplasia: linear, pits, and groove. Examined samples derive from archeological material dated on XVII-XVIII AD and excavated in Poland. In the current study we proved that micro-CT scanning is a powerful technique not only for imaging all kinds of the enamel hypoplasia but also allows to perform accurate measurements of the enamel defects. We figure out that contrary to the classical method of scoring enamel defects, the micro-computed tomography yields adequate data which serve for estimating the length of stress episode and length of interval between them.

Parallel multipoint recording of aligned and cultured neurons on corresponding Micro Channel Array toward on-chip cell analysis.

PubMed

Tonomura, W; Moriguchi, H; Jimbo, Y; Konishi, S

2008-01-01

This paper describes an advanced Micro Channel Array (MCA) so as to record neuronal network at multiple points simultaneously. Developed MCA is designed for neuronal network analysis which has been studied by co-authors using MEA (Micro Electrode Arrays) system. The MCA employs the principle of the extracellular recording. Presented MCA has the following advantages. First of all, the electrodes integrated around individual micro channels are electrically isolated for parallel multipoint recording. Sucking and clamping of cells through micro channels is expected to improve the cellular selectivity and S/N ratio. In this study, hippocampal neurons were cultured on the developed MCA. As a result, the spontaneous and evoked spike potential could be recorded by sucking and clamping the cells at multiple points. Herein, we describe the successful experimental results together with the design and fabrication of the advanced MCA toward on-chip analysis of neuronal network.

Modeling and measurement of electrostatic micromirror array fabricated with single-layer polysilicon micromachining technology

NASA Astrophysics Data System (ADS)

Min, Young-Hoon; Kim, Yong-Kweon

1998-09-01

A silicon based micro mirror array is a highly efficient component for use in optical applications as adaptive optical systems and optical correlators. Many types of micro mirror or micro mirror array have been studied and proposed in order to obtain the optimal performance according to their own purposes. A micro mirror array designed, fabricated and tested in this paper consists of 5 X 5 single layer polysilicon-based, electrostatically driven actuators. The micro mirror array for the optical phase modulation is made by using only two masks and can be driven independently by 25 channel circuits. About 6 (pi) phase modulation is obtained in He-Ne laser ((lambda) equals 633 nm) with 67% fill-factor. In this paper, the deflection characteristics of the actuators in controllable range were studied. The experimental results show that the deflection characteristics is much dependent upon a residual stress in flexure, the initial curvature of mirror due to stress gradient and an electrostatic force acted on other element except for mirror itself. The modeling results agree well with the experimental results. Also, it is important to fabricate a flat mirror that is not initially curved because the curved mirror brings a bad performance in optical use. Therefore, a new method to obtain the flat mirror by using the gold metallization in spite of the residual stress unbalance is proposed in this paper.

High-efficiency integrated piezoelectric energy harvesting systems

NASA Astrophysics Data System (ADS)

Hande, Abhiman; Shah, Pradeep

2010-04-01

This paper describes hierarchically architectured development of an energy harvesting (EH) system that consists of micro and/or macro-scale harvesters matched to multiple components of remote wireless sensor and communication nodes. The micro-scale harvesters consist of thin-film MEMS piezoelectric cantilever arrays and power generation modules in IC-like form to allow efficient EH from vibrations. The design uses new high conversion efficiency thin-film processes combined with novel cantilever structures tuned to multiple resonant frequencies as broadband arrays. The macro-scale harvesters are used to power the collector nodes that have higher power specifications. These bulk harvesters can be integrated with efficient adaptive power management circuits that match transducer impedance and maximize power harvested from multiple scavenging sources with very low intrinsic power consumption. Texas MicroPower, Inc. is developing process based on a composition that has the highest reported energy density as compared to other commercially available bulk PZT-based sensor/actuator ceramic materials and extending it to thin-film materials and miniature conversion transducer structures. The multiform factor harvesters can be deployed for several military and commercial applications such as underground unattended sensors, sensors in oil rigs, structural health monitoring, supply chain management, and battlefield applications such as sensors on soldier apparel, equipment, and wearable electronics.

Fabrication of solution-processed InSnZnO/ZrO2 thin film transistors.

PubMed

Hwang, Soo Min; Lee, Seung Muk; Choi, Jun Hyuk; Lim, Jun Hyung; Joo, Jinho

2013-11-01

We fabricated InSnZnO (ITZO) thin-film transistors (TFTs) with a high-permittivity (K) ZrO2 gate insulator using a solution process and explored the microstructure and electrical properties. ZrO2 and ITZO (In:Sn:Zn = 2:1:1) precursor solutions were deposited using consecutive spin-coating and drying steps on highly doped p-type Si substrate, followed by annealing at 700 degrees C in ambient air. The ITZO/ZrO2 TFT device showed n-channel depletion mode characteristics, and it possessed a high saturation mobility of approximately 9.8 cm2/V x s, a small subthreshold voltage swing of approximately 2.3 V/decade, and a negative V(TH) of approximately 1.5 V, but a relatively low on/off current ratio of approximately 10(-3). These results were thought to be due to the use of the high-kappa crystallized ZrO2 dielectric (kappa approximately 21.8) as the gate insulator, which could permit low-voltage operation of the solution-processed ITZO TFT devices for applications to high-throughput, low-cost, flexible and transparent electronics.

Electrical instability of high-mobility zinc oxynitride thin-film transistors upon water exposure

NASA Astrophysics Data System (ADS)

Kim, Dae-Hwan; Jeong, Hwan-Seok; Kwon, Hyuck-In

2017-03-01

We investigate the effects of water absorption on the electrical performance and stability in high-mobility zinc oxynitride (ZnON) thin-film transistors (TFTs). The ZnON TFT exhibits a smaller field-effect mobility, lower turn-on voltage, and higher subthreshold slope with a deteriorated electrical stability under positive gate bias stresses after being exposed to water. From the Hall measurements, an increase of the electron concentration and a decrease of the Hall mobility are observed in the ZnON thin film after water absorption. The observed phenomena are mainly attributed to the water molecule-induced increase of the defective ZnXNY bond and the oxygen vacancy inside the ZnON thin film based on the x-ray photoelectron spectroscopy analysis.

Micro-Nanostructures of Cellulose-Collagen for Critical Sized Bone Defect Healing.

PubMed

Aravamudhan, Aja; Ramos, Daisy M; Nip, Jonathan; Kalajzic, Ivo; Kumbar, Sangamesh G

2018-02-01

Bone tissue engineering strategies utilize biodegradable polymeric matrices alone or in combination with cells and factors to provide mechanical support to bone, while promoting cell proliferation, differentiation, and tissue ingrowth. The performance of mechanically competent, micro-nanostructured polymeric matrices, in combination with bone marrow stromal cells (BMSCs), is evaluated in a critical sized bone defect. Cellulose acetate (CA) is used to fabricate a porous microstructured matrix. Type I collagen is then allowed to self-assemble on these microstructures to create a natural polymer-based, micro-nanostructured matrix (CAc). Poly (lactic-co-glycolic acid) matrices with identical microstructures serve as controls. Significantly higher number of implanted host cells are distributed in the natural polymer based micro-nanostructures with greater bone density and more uniform cell distribution. Additionally, a twofold increase in collagen content is observed with natural polymer based scaffolds. This study establishes the benefits of natural polymer derived micro-nanostructures in combination with donor derived BMSCs to repair and regenerate critical sized bone defects. Natural polymer based materials with mechanically competent micro-nanostructures may serve as an alternative material platform for bone regeneration. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

TUW at the First Total Recall Track

DTIC Science & Technology

2015-11-20

Appen- dix A were ignored. 2.1. Term weighting. The bmi used the basic tf.idf weighting scheme, as given by: (1) weightT (t, d) = (1 + log( tft ,d)) ⇤ log(N...dft); where t is a term, d a document, tft ,d the term frequency, dft the document frequency, and N is the number of documents in the collection. For...save us some training e↵ort. The used weight, marked by “B” in the run names, is given by: (2) weightB(t, d) = tft ,d⇣ 1 mavgtf avgtfd mavgtf + (1 1

Amorphous Silicon: Flexible Backplane and Display Application

NASA Astrophysics Data System (ADS)

Sarma, Kalluri R.

Advances in the science and technology of hydrogenated amorphous silicon (a-Si:H, also referred to as a-Si) and the associated devices including thin-film transistors (TFT) during the past three decades have had a profound impact on the development and commercialization of major applications such as thin-film solar cells, digital image scanners and X-ray imagers and active matrix liquid crystal displays (AMLCDs). Particularly, during approximately the past 15 years, a-Si TFT-based flat panel AMLCDs have been a huge commercial success. a-Si TFT-LCD has enabled the note book PCs, and is now rapidly replacing the venerable CRT in the desktop monitor and home TV applications. a-Si TFT-LCD is now the dominant technology in use for applications ranging from small displays such as in mobile phones to large displays such as in home TV, as well-specialized applications such as industrial and avionics displays.

Correlation between Ti source/drain contact and performance of InGaZnO-based thin film transistors

NASA Astrophysics Data System (ADS)

Choi, Kwang-Hyuk; Kim, Han-Ki

2013-02-01

Ti contact properties and their electrical contribution to an amorphous InGaZnO (a-IGZO) semiconductor-based thin film transistor (TFT) were investigated in terms of chemical, structural, and electrical considerations. TFT device parameters were quantitatively studied by a transmission line method. By comparing various a-IGZO TFT parameters with those of different Ag and Ti source/drain electrodes, Ti S/D contact with an a-IGZO channel was found to lead to a negative shift in VT (-Δ 0.52 V). This resulted in higher saturation mobility (8.48 cm2/Vs) of a-IGZO TFTs due to effective interfacial reaction between Ti and an a-IGZO semiconducting layer. Based on transmission electron microcopy, x-ray photoelectron depth profile analyses, and numerical calculation of TFT parameters, we suggest a possible Ti contact mechanism on semiconducting a-IGZO channel layers for TFTs.

microRNA expression profiling in fetal single ventricle malformation identified by deep sequencing.

PubMed

Yu, Zhang-Bin; Han, Shu-Ping; Bai, Yun-Fei; Zhu, Chun; Pan, Ya; Guo, Xi-Rong

2012-01-01

microRNAs (miRNAs) have emerged as key regulators in many biological processes, particularly cardiac growth and development, although the specific miRNA expression profile associated with this process remains to be elucidated. This study aimed to characterize the cellular microRNA profile involved in the development of congenital heart malformation, through the investigation of single ventricle (SV) defects. Comprehensive miRNA profiling in human fetal SV cardiac tissue was performed by deep sequencing. Differential expression of 48 miRNAs was revealed by sequencing by oligonucleotide ligation and detection (SOLiD) analysis. Of these, 38 were down-regulated and 10 were up-regulated in differentiated SV cardiac tissue, compared to control cardiac tissue. This was confirmed by real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis. Predicted target genes of the 48 differentially expressed miRNAs were analyzed by gene ontology and categorized according to cellular process, regulation of biological process and metabolic process. Pathway-Express analysis identified the WNT and mTOR signaling pathways as the most significant processes putatively affected by the differential expression of these miRNAs. The candidate genes involved in cardiac development were identified as potential targets for these differentially expressed microRNAs and the collaborative network of microRNAs and cardiac development related-mRNAs was constructed. These data provide the basis for future investigation of the mechanism of the occurrence and development of fetal SV malformations.

Microsystem enabled photovoltaic modules and systems

DOEpatents

Nielson, Gregory N; Sweatt, William C; Okandan, Murat

2015-05-12

A microsystem enabled photovoltaic (MEPV) module including: an absorber layer; a fixed optic layer coupled to the absorber layer; a translatable optic layer; a translation stage coupled between the fixed and translatable optic layers; and a motion processor electrically coupled to the translation stage to controls motion of the translatable optic layer relative to the fixed optic layer. The absorber layer includes an array of photovoltaic (PV) elements. The fixed optic layer includes an array of quasi-collimating (QC) micro-optical elements designed and arranged to couple incident radiation from an intermediate image formed by the translatable optic layer into one of the PV elements such that it is quasi-collimated. The translatable optic layer includes an array of focusing micro-optical elements corresponding to the QC micro-optical element array. Each focusing micro-optical element is designed to produce a quasi-telecentric intermediate image from substantially collimated radiation incident within a predetermined field of view.

Low temperature cured poly-siloxane passivation for highly reliable a-InGaZnO thin-film transistors

NASA Astrophysics Data System (ADS)

Yoshida, Naofumi; Bermundo, Juan Paolo; Ishikawa, Yasuaki; Nonaka, Toshiaki; Taniguchi, Katsuto; Uraoka, Yukiharu

2018-05-01

Low temperature processable passivation materials are necessary to fabricate highly reliable amorphous InGaZnO (a-IGZO) thin-film transistors (TFT) on organic substrates for flexible device applications. We investigated 3 types of poly-siloxane (Poly-SX) passivation layers fabricated by a solution process and cured at low temperatures (180 °C) for a-IGZO TFTs. This passivation layer greatly improves the stability of the a-IGZO device even after being subjected to positive (PBS) and negative bias stress (NBS). The field effect mobility (μ) of MePhQ504010 passivated on the TFT reached 8.34 cm2/Vs and had a small threshold voltage shift of 0.9 V after PBS, -0.8 V after NBS without the hump phenomenon. Furthermore, we analyzed the hydrogen and hydroxide states in the a-IGZO layer by secondary ion mass spectrometry and X-ray photoelectron spectroscopy to determine the cause of excellent electrical properties despite the curing performed at a low temperature. These results show the potential of the solution processed Poly-SX passivation layer for flexible devices.

Nano-stepper-driven optical shutter for applications in free-space micro-optics

NASA Astrophysics Data System (ADS)

Zawadzka, Justyna; Li, Lijie; Unamuno, Anartz; Uttamchandani, Deepak G.

2002-09-01

In this paper we report a simple design of a micro-optical shutter/attenuator. The standard MUMPS process was used to fabricate the device. A vertically erected, gold-coated, 200x300 mm side length micro-mirror was precisely placed between the end faces of two closely spaced optical fibers. The position of the micro-mirror with respect to the optical fiber end face was controlled by a nano-stepping motor array. Optical and mechanical tests were performed on the device. A 1.55 mm laser beam was sent along the optical fiber. When the micro-mirror was removed from the front of the fiber, the coupling efficiency between two fibers was -10 dBm. Once the micro-mirror was placed in the optical path the coupling efficiency dropped to -51.5 dBm. The best attenuation was obtained when the micro-mirror blocked the whole cross-section of the laser beam diameter. It is evident that the device can operate as a high precision fiber optic attenuator or shutter.

Smart integration of silicon nanowire arrays in all-silicon thermoelectric micro-nanogenerators

NASA Astrophysics Data System (ADS)

Fonseca, Luis; Santos, Jose-Domingo; Roncaglia, Alberto; Narducci, Dario; Calaza, Carlos; Salleras, Marc; Donmez, Inci; Tarancon, Albert; Morata, Alex; Gadea, Gerard; Belsito, Luca; Zulian, Laura

2016-08-01

Micro and nanotechnologies are called to play a key role in the fabrication of small and low cost sensors with excellent performance enabling new continuous monitoring scenarios and distributed intelligence paradigms (Internet of Things, Trillion Sensors). Harvesting devices providing energy autonomy to those large numbers of microsensors will be essential. In those scenarios where waste heat sources are present, thermoelectricity will be the obvious choice. However, miniaturization of state of the art thermoelectric modules is not easy with the current technologies used for their fabrication. Micro and nanotechnologies offer an interesting alternative considering that silicon in nanowire form is a material with a promising thermoelectric figure of merit. This paper presents two approaches for the integration of large numbers of silicon nanowires in a cost-effective and practical way using only micromachining and thin-film processes compatible with silicon technologies. Both approaches lead to automated physical and electrical integration of medium-high density stacked arrays of crystalline or polycrystalline silicon nanowires with arbitrary length (tens to hundreds microns) and diameters below 100 nm.

Electrical responses of artificial DNA nanostructures on solution-processed In-Ga-Zn-O thin-film transistors with multistacked active layers.

PubMed

Jung, Joohye; Kim, Si Joon; Yoon, Doo Hyun; Kim, Byeonghoon; Park, Sung Ha; Kim, Hyun Jae

2013-01-01

We propose solution-processed In-Ga-Zn-O (IGZO) thin-film transistors (TFTs) with multistacked active layers for detecting artificial deoxyribonucleic acid (DNA). Enhanced sensing ability and stable electrical performance of TFTs were achieved through use of multistacked active layers. Our IGZO TFT had a turn-on voltage (V(on)) of -0.8 V and a subthreshold swing (SS) value of 0.48 V/decade. A dry-wet method was adopted to immobilize double-crossover DNA on the IGZO surface, after which an anomalous hump effect accompanying a significant decrease in V(on) (-13.6 V) and degradation of SS (1.29 V/decade) was observed. This sensing behavior was attributed to the middle interfaces of the multistacked active layers and the negatively charged phosphate groups on the DNA backbone, which generated a parasitic path in the TFT device. These results compared favorably with those reported for conventional field-effect transistor-based DNA sensors with remarkable sensitivity and stability.

Comparison of pattern VEP results acquired using CRT and TFT stimulators in the clinical practice.

PubMed

Nagy, Balázs Vince; Gémesi, Szabolcs; Heller, Dávid; Magyar, András; Farkas, Agnes; Abrahám, György; Varsányi, Balázs

2011-06-01

There are several electrophysiological systems available commercially. Usually, control groups are required to compare their results, due to the differences between display types. Our aim was to examine the differences between CRT and LCD/TFT stimulators used in pattern VEP responses performed according to the ISCEV standards. We also aimed to check different contrast values toward thresholds. In order to obtain more precise results, we intended to measure the intensity and temporal response characteristics of the monitors with photometric methods. To record VEP signals, a Roland RetiPort electrophysiological system was used. The pattern VEP tests were carried out according to ISCEV protocols on a CRT and a TFT monitor consecutively. Achromatic checkerboard pattern was used at three different contrast levels (maximal, 75, 25%) using 1° and 15' check sizes. Both CRT and TFT displays were luminance and contrast matched, according to the gamma functions based on measurements at several DAC values. Monitor-specific luminance parameters were measured by means of spectroradiometric instruments. Temporal differences between the displays' electronic and radiometric signals were measured with a device specifically built for the purpose. We tested six healthy control subjects with visual acuity of at least 20/20. The tests were performed on each subject three times on different days. We found significant temporal differences between the CRT and the LCD monitors at all contrast levels and spatial frequencies. In average, the latency times were 9.0 ms (±3.3 ms) longer with the TFT stimulator. This value is in accordance with the average of the measured TFT input-output temporal difference values (10.1 ± 2.2 ms). According to our findings, measuring the temporal parameters of the TFT monitor with an adequately calibrated measurement setup and correcting the VEP data with the resulting values, the VEP signals obtained with different display types can be transformed to be comparable.

TiO2 micro-flowers composed of nanotubes and their application to dye-sensitized solar cells.

PubMed

Kim, Woong-Rae; Park, Hun; Choi, Won-Youl

2014-02-24

TiO2 micro-flowers were made to bloom on Ti foil by the anodic oxidation of Ti-protruding dots with a cylindrical shape. Arrays of the Ti-protruding dots were prepared by photolithography, which consisted of coating the photoresists, attaching a patterned mask, illuminating with UV light, etching the Ti surface by reactive ion etching (RIE), and stripping the photoresist on the Ti foil. The procedure for the blooming of the TiO2 micro-flowers was analyzed by field emission scanning electron microscopy (FESEM) as the anodizing time was increased. Photoelectrodes of dye-sensitized solar cells (DSCs) were fabricated using TiO2 micro-flowers. Bare TiO2 nanotube arrays were used for reference samples. The short-circuit current (Jsc) and the power conversion efficiency of the DSCs based on the TiO2 micro-flowers were 4.340 mA/cm2 and 1.517%, respectively. These values of DSCs based on TiO2 micro-flowers were higher than those of bare samples. The TiO2 micro-flowers had a larger surface area for dye adsorption compared to bare TiO2 nanotube arrays, resulting in improved Jsc characteristics. The structure of the TiO2 micro-flowers allowed it to adsorb dyes very effectively, also demonstrating the potential to achieve higher power conversion efficiency levels for DSCs compared to a bare TiO2 nanotube array structure and the conventional TiO2 nanoparticle structure.