An Organic Active-Matrix Imager Nausieda, I.; Ryu Kyungbum; Kymissis, I. ...
IEEE transactions on electron devices,
02/2008, Letnik:
55, Številka:
2
Journal Article
Recenzirano
In this paper, a proof of concept 4 x 4 active-matrix imager fabricated at near room temperature (< 95 degC) is presented. Conventional photolithography and inkjet printing were used to pattern ...integrated organic FETs and photoconductors. The design and characterization of a pixel circuit is described. A simple first-order calibration technique is used to partially compensate for fixed pattern noise. Following the calibration, the imager is shown to correctly image a "T" pattern.
We developed a fabrication process for embedding a dense array (108 cm−2) of high-aspect-ratio silicon nanowires (200 nm diameter and 10 m tall) in a dielectric matrix and then structured/exposed the ...tips of the nanowires to form self-aligned gate field emitter arrays using chemical mechanical polishing (CMP). Using this structure, we demonstrated a high current density (100 A cm−2), uniform, and long lifetime (>100 h) silicon field emitter array architecture in which the current emitted by each tip is regulated by the silicon nanowire current limiter connected in series with the tip. Using the current voltage characteristics and with the aid of numerical device models, we estimated the tip radius of our field emission arrays to be 4.8 nm, as consistent with the tip radius measured using a scanning electron microscope (SEM).
This paper reports the design, fabrication, and experimental characterization of a fully microfabricated planar array of externally fed electrospray emitters that produces heavy molecular ions from ...the ionic liquids EMI-BF 4 and EMI-Im. The microelectromechanical systems (MEMS) electrospray array is composed of the following two microfabricated parts: 1) an emitter die with as many as 502 emitters in 1.13 cm 2 and 2) an extractor component that provides assembly alignment, electrical insulation, and a common bias voltage to the emitter array. The devices were created using Pyrex and silicon substrates, as well as microfabrication techniques such as deep reactive ion etching, low-temperature fusion bonding, and anodic bonding. The emitters are coated with black silicon, which acts as a wicking material for transporting the liquid to the emitter tips. The extractor electrode uses a 3-D MEMS packaging technology that allows hand assembly of the two components with micrometer-level precision. Experimental characterization of the MEMS electrospray array includes current-voltage characteristics, time-of-flight mass spectrometry, beam divergence, and imprints on a collector. The data show that with both ionic liquids and in both polarities, the electrospray array works in the pure ionic regime, emitting ions with as little as 500 V of bias voltage. The data suggest that the MEMS electrospray array ion source could be used in applications such as coating, printing, etching, and nanosatellite propulsion.
A method for the fabrication of thick films of porous anodic alumina on rigid substrates is described. The anodic alumina film was generated by the anodization of an aluminum film evaporated on the ...substrate. The morphology of the barrier layer between the porous film and the substrate was different from that of anodic films grown on aluminum substrates. The removal of the barrier layer and the electrochemical growth of nanowires within the ordered pores were accomplished without the need to remove the anodic film from the substrate. We fabricated porous anodic alumina samples over large areas (up to 70 cm2), and deposited in them nanowire arrays of various materials. Long nanowires were obtained with lengths of at least 9 μm and aspect ratios as high as 300. Due to their mechanical robustness and the built‐in contact between the conducting substrate and the nanowires, the structures were useful for electrical transport measurements on the arrays. The method was also demonstrated on patterned and non‐planar substrates, further expanding the range of applications of these porous alumina and nanowire assemblies.
Large‐area porous anodic alumina films lacking a barrier layer, and nanowire arrays of high aspect ratio nanowires (∼102) in direct contact with a conductive film, have been formed on rigid substrates. The effect of different substrates on the morphology of the film and the barrier layer was examined, and the ease of manipulation of the structures was demonstrated by patterning the films and by nanowire transport measurements.
This paper reports the design, fabrication, and experimental characterization of a planar array of micro-fabricated electrospray emitters intended for space propulsion applications in ...micro-satellites. The engine uses the ionic liquid EMI-BF 4 as propellant. Electrospray engines take advantage of the electrohydrodynamic effect known as Taylor cone to produce thrust. The array is designed with an open architecture and it is composed of a set of spikes, i.e., emitters, coming out from a propellant pool. There are two configurations for the emitters: fully sharpened slender emitters, i.e., pencils, and truncated pyramidal emitters, i.e., volcanoes. The arrays have between 4 and 1024 emitters in an active area of 0.64 cm 2 . The surface of the engine (tank and emitters) is covered with "black silicon" that acts as wicking material. The micro-fabrication of the engine is described. The paper reports experimental characterization of the hydraulics system including wettability tests, current/emitter-voltage characteristics, and imprints of the exit stream on a collector. Preliminary results demonstrating the feasibility of obtaining substantially larger emission currents at the same extraction voltage by controlling the temperature are also reported. The paper compares the experimental current/emitter-voltage characteristics with relevant theories of field emission of electrons
Threshold-voltage control is critical to the further development of pentacene organic field-effect transistors (OFETs). In this paper, we demonstrate that the threshold voltage can be tuned through ...chemical treatment of the gate dielectric layer. We show that oxygen plasma treatment of an organic polymer gate dielectric, parylene, introduces traps at the semiconductor-dielectric interface that strongly affect the OFET performance. Atomic force microscopy, optical microscopy using crossed-polarizers, and current-voltage and capacitance-voltage characterization were performed on treated and untreated devices. A model is presented to account for the effects of trap-introduced charges, both 1) fixed charges (2.0/spl times/10/sup -6/ C/cm/sup 2/) that shift the threshold voltage from -17 to +116 V and 2) mobile charges (1.1/spl times/10/sup -6/ C/cm/sup 2/) that increase the parasitic bulk conductivity. This technique offers a potential method of tuning threshold voltage at the process level.
Background: Kidney involvement in coronavirus disease 2019 (COVID-19) pathology has been supported by high frequency of angiotensin-converting enzyme 2 (ACE2) expression on renal cells and reports of ...acute kidney injury. However, the association between host viral load and kidney function is not clear. Aim: In this study, plasma levels of renal markers (urea nitrogen, creatinine, and estimated glomerular filtration rate (eGFR)) and electrolytes (sodium, potassium, chlorine, and bicarbonate) were assessed in relation to SARS-CoV-2 viral load of COVID-19 patients. Patients and Methods: This cross-sectional study involved 144 consenting COVID-19 patients admitted to the Ogun state COVID-19 isolation center between May and December 2020. All participants presented with mild respiratory symptoms and did not require ICU admission or ventilation support. Data included reverse transcriptase polymerase chain reaction (RT-PCR) cycle threshold (CT) value, blood urea nitrogen (BUN), creatinine, sodium, potassium, chlorine, bicarbonate measurements, and glomerular filtration rate. Reference intervals were used as comparators, and multiple linear regression model was fitted. Statistical significance was set at P < 0.05. Results: BUN level and creatinine were elevated in 4 (2.8%) and 42 (29.2%) patients, respectively, with lowered eGFR observed in 37 (25.7%) patients. Hyponatremia and hypokalemia were observed in 35 (24.3%) and 21 (14.6%) patients, respectively, while hypochloremia was observed in 21 (14.6%) patients. Lowered bicarbonate was observed in 29 (20.1%) patients. Linear regression showed statistically significant association (R2 = 0.340, P = 0.032) between RT-PCR CT value and eGFR (β = 0.006, P = 0.017) as well as HCO3 (β = -0.262, P = 0.036). Conclusion: COVID-19 patients with mild respiratory symptoms exhibited renal abnormalities, electrolytes, and acid-base imbalances which were partly associated with SARS-CoV-2 viral load.
This paper reports the design, fabrication, and characterization of low-cost out-of-plane quadrupole mass filters that use commercially available dowel pins as electrode rods. The quadrupoles ...implement a 3-D MEMS packaging technology that relies on deep-reactive ion etching (DRIE)-patterned deflection springs for alignment. Quadrupoles with rod diameter ranging from 0.25 to 1.58 mm and aspect ratio of 30 to 60 were built and tested at RF frequencies of 1.44, 2.0, and 4 MHz. Assembled devices operated in the first stability region achieved a maximum mass range of 650 amu, while a minimum half-peak width of 0.4 amu at mass 28 was obtained in the second stability region. Operation in the second stability region provides a means to higher resolution, smoother peaks, and removed peak splitting at the expense of transmission. The ultimate resolution of the reported quadrupoles is also discussed.
COVID-19 is one of the greatest human global health challenges that causes economic meltdown of many nations. In this study, we develop an SIR-type model which captures both human-to-human and ...environment-to-human-to-environment transmissions that allows the recruitment of corona viruses in the environment in the midst of booster vaccine program. Theoretically, we prove some basic properties of the full model as well as investigate the existence of SARS-CoV-2-free and endemic equilibria. The SARS-CoV-2-free equilibrium for the special case, where the constant inflow of corona virus into the environment by any other means, Ω is suspended (Ω=0) is globally asymptotically stable when the effective reproduction number R0c<1 and unstable if otherwise. Whereas in the presence of free-living Corona viruses in the environment (Ω>0), the endemic equilibrium using the centre manifold theory is shown to be stable globally whenever R0c>1. The model is extended into optimal control system and analyzed analytically using Pontryagin's Maximum Principle. Results from the optimal control simulations show that strategy E for implementing the public health advocacy, booster vaccine program, treatment of isolated people and disinfecting or fumigating of surfaces and dead bodies before burial is the most effective control intervention for mitigating the spread of Corona virus. Importantly, based on the available data used, the study also revealed that if at least 70% of the constituents followed the aforementioned public health policies, then herd immunity could be achieved for COVID-19 pandemic in the community.
COVID-19; Booster vaccine program; Environmental contamination; Bifurcation; Optimal control analysis
Two near-ultraviolet (UV) sensors based on solution-grown zinc oxide (ZnO) nanowires (NWs) which are only sensitive to photo-excitation at or below 400 nm wavelength have been fabricated and ...characterized. Both devices keep all processing steps, including nanowire growth, under 100 °C for compatibility with a wide variety of substrates. The first device type uses a single optical lithography step process to allow simultaneous in situ horizontal NW growth from solution and creation of symmetric ohmic contacts to the nanowires. The second device type uses a two-mask optical lithography process to create asymmetric ohmic and Schottky contacts. For the symmetric ohmic contacts, at a voltage bias of 1 V across the device, we observed a 29-fold increase in current in comparison to dark current when the NWs were photo-excited by a 400 nm light-emitting diode (LED) at 0.15 mW cm−2 with a relaxation time constant (τ) ranging from 50 to 555 s. For the asymmetric ohmic and Schottky contacts under 400 nm excitation, τ is measured between 0.5 and 1.4 s over varying time internals, which is ∼2 orders of magnitude faster than the devices using symmetric ohmic contacts.
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