One-step air bridge fabrication technique using 3D e-beam lithography

A new technique is demonstrated for the realisation of air bridges using one lithographic step. Gray scale lithography is used for the formation of 3D profiles on polymethyl methacrylate (PMMA) where a variable dose exposure is applied to create a trapezoid profile for the air bridge. In previous 3D electron beam lithography (EBL) methods the span area was exposed to a low dose or a low acceleration voltage [1,2,3]. Thus, the required discontinuity with the surrounding area for the lift-off process was created. In this technique, no exposure of the span area is needed. Another exposure of a gradient dose is applied to the sides of the highest part of the air bridge. The created profile, after developing the resist, is depicted in Figure 1. The surfaces with red and blue colour represent the metal to form the air bridge and the metal to lift-off, respectively. Using this configuration, the deposited metal at the sides of the top part of the air bridge is connected to the surrounding metal to lift-off and disconnect from the air bridge. The electron dose used in this area has to be smaller than the minimum dose that penetrates the total resist layer, so that the deposited metal does not reach the substrate. This method takes maximum advantage of the resist thickness for the fabrication of high structures, as no part of the resist is sacrifice

Plasmonic gold nanodiscs using piezoelectric substrate birefringence for liquid sensing

This article presents the simulation, fabrication, and experimental characterization of a surface plasmonic resonance (SPR) sensor integrated with an acoustic sensing compatible substrate. The SPR sensor is designed to work in the visible region with gold nanodisc arrays fabricated on LiNbO3, which is both piezoelectric and birefringent. A linear relationship between resonance wavelength and varying liquid refractive indices were observed in experiments, and a sensitivity of 165 nm/refractive index unit was obtained. Polarization effects of the birefringent property of the Y-cut LiNbO3 substrate have been investigated, which can also be applied to X-cut LiNbO3. Our study demonstrates the feasibility of an SPR sensor device utilizing a birefringent substrate, which has acoustic wave compatibility and can pave the way toward much more robust and flexible biosensing device

Sedimentology and porewater isotope chemistry of Quaternary deposits from the St. Clair delta, Walpole Island, Ontario, Canada

Walpole Island is part of a large freshwater delta complex located at the St. Clair River mouth in southwestern Ontario. Petrographic study of 3 continuously sampled sediment cores taken along a 14 km north-south transect of the island show that the stratigraphy of Walpole Island Quaternary sediments reflects a general retreat of the Laurentide Ice Sheet northwards from the area. From top to bottom, the stratigraphy is as follows: (a) Nipissing to Modern Great Lakes stage sandy deltaic sediments; (b) an Early Holocene green accretion gley found only in the middle core; (c) Two Creeks Interstade, Greatlakean Stade, and Early Holocene non-rhythmically stratified lacustrine clayey silt; (d) Early Mackinaw Interstade to Early Two Creeks Interstade varved glaciolacustrine clayey silt; (e) Port Bruce Stade Rannoch Till; a waterlain, carbonate-rich clayey silt till containing numerous inclusions of Erie Interstade glaciolacustrine sediments and bedrock clasts; and (f) a coarser, sandy lodgment facies of the Rannoch Till. Porewater \rm\delta\sp{18}O,\ \delta D\ and\ \delta\sp{13}C\sb{DIC} value profiles for cores located in the north and middle of Walpole Island indicate that older ($\u3e$10000 y.b.p.), deeper, glacigenic porewaters have mixed with, and have been displaced by younger ($\u3c$10000 y.b.p.) surficial waters. Porewater \rm\delta\sp{18}O,\ \delta D\ and\ \delta\sp{13}C\sb{DIC} value profiles for the core from the southern portion of Walpole Island indicate that modern St. Clair River water has penetrated the length of the 20 m core via fractures, effectively displacing all glacigenic porewater. Fracturing and faulting or slumping are clearly visible throughout the southern core, which is located on the trend of the Electric Fault. (Abstract shortened by UMI.)Dept. of Earth Sciences. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1995 .C85. Source: Masters Abstracts International, Volume: 34-06, page: 2323. Thesis (M.Sc.)--University of Windsor (Canada), 1995

Evaluation of the 20,000 days campaign

The aim of Counties Manuaku District Health Board (CMDHB) 20,000 Days Campaign was to give back to the community 20,000 healthy and well days to avoid predicted growth in hospital bed days. After tracking the difference between projected demand and actual use, at the end of the Campaign on 1st July 2013, CMDHB reported that 23,060 bed days were given back to the people of Counties Manukau. This evaluation report explains how using the Institute of Healthcare Improvement Breakthrough Series the Campaign was run with the expectation that small immediate changes to practical problems (in this case the work of 13 Collaborative teams), will accumulate into large effects (a reduction of 20,000 bed days against predicted bed days use by July 2013). The evaluation found the Campaign did save bed days, though attributing causality was always going to be difficult, and overall the Campaign was very successful in keeping the energy and motivation of participants

Recent Progress in Plasmonic Colour Filters for Image Sensor and Multispectral Applications

Using nanostructured thin metal films as colour filters offers several important advantages, in particular high tunability across the entire visible spectrum and some of the infrared region, and also compatibility with conventional CMOS processes. Since 2003, the field of plasmonic colour filters has evolved rapidly and several different designs and materials, or combination of materials, have been proposed and studied. In this paper we present a simulation study for a single- step lithographically patterned multilayer structure able to provide competitive transmission efficiencies above 40% and contemporary FWHM of the order of 30 nm across the visible spectrum. The total thickness of the proposed filters is less than 200 nm and is constant for every wavelength, unlike e.g. resonant cavity-based filters such as Fabry-Perot that require a variable stack of several layers according to the working frequency, and their passband characteristics are entirely controlled by changing the lithographic pattern. It will also be shown that a key to obtaining narrow-band optical response lies in the dielectric environment of a nanostructure and that it is not necessary to have a symmetric structure to ensure good coupling between the SPPs at the top and bottom interfaces. Moreover, an analytical method to evaluate the periodicity, given a specific structure and a desirable working wavelength, will be proposed and its accuracy demonstrated. This method conveniently eliminate the need to optimize the design of a filter numerically, i.e. by running several time-consuming simulations with different periodicities. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

CMOS Terahertz Metamaterial Based 64 × 64 Bolometric Detector Arrays

We present two terahertz detectors composed of microbolometer sensors (vanadium oxide and silicon pn diode) and metamaterial absorbers monolithically integrated into a complementary metal oxide semiconductor (CMOS) process. The metamaterial absorbers were created using the metal-dielectric-metal layers of a commercial CMOS technology resulting in low-cost terahertz detectors. The scalability of this technology was used to form a 64 × 64 pixel terahertz focal plane array

Co-fabrication of planar Gunn diode and HEMT on InP substrate

We present the co-fabrication of planar Gunn diodes and high electron mobility transistors (HEMTs) on an Indium Phosphide (InP) substrate for the first time. Electron beam lithography (EBL) has been used extensively for the complete fabrication procedure and a 70 nm T-gate technology was incorporated for the enhancement of the small-signal characteristics of the HEMT. Diodes with anode-to-cathode separation (Lac) down to 1 μm and 120 μm width where shown to oscillate up to 204 GHz. The transistor presents a cut-off frequency (fT) of 220 GHz, with power gain up to 330 GHz (f<sub>max</sub>). The integration of the two devices creates the potential for the realisation of high-power, high-frequency MMIC Gunn oscillators, circuits and systems

The early development of the reflecting telescope in Britain

The first effective demonstration of a telescope using reflecting optics was made by Isaac Newton, and his invention was given wide- spread publicity by the Royal Society of London in 1672. Newtonts instrument was closely associated with the introduction of his new theory of the nature of white light and colour, and for Newton his telescopes practicability remained important to the acceptance of his optical theory. Newtonts telescope, influenced to some extent by the earlier work of James Gregory, encouraged the Royal Society to promote more ambitious trials, but instruments by Robert Hooke and Christopher Cock, and by Newton himself, achieved only limited success.Renewed interest in the reflector followed its re- emergence in Newtonts Opticks of 1704. John Hadleyes successful revival of Newtones instrument led in turn to the establishment in London of competitive commercial manufacture of reflectors in the early 18th century, and by 1710 the market was dominated by the instruments of James Short.Contemporary references to the reflecting telescopes of Newton and others have been analysed to allow the historical development of this work to be established more reliably, and to propose a relation- ship between the various instruments that may be ascribed to Newton. The emphasis has therefore been placed on the instrumentation itself, on practical detail, and on questions of provenance

Metabolomics on integrated circuit

We have demonstrated a chip-based diagnostics tool for the quantification of metabolites, using specific enzymes, to study enzyme kinetics and calculate the Michaelis-Menten constant. An array of 256×256 ion-sensitive field effect transistors (ISFETs) fabricated in a complementary metal oxide semiconductor (CMOS) process is used for this prototype. We have used hexokinase enzyme reaction on the ISFET CMOS chip with glucose concentration in the physiological range of 0.05 mM – 231 mM and successfully studied the enzyme kinetics of hexokinase in detail. This will promote future research towards multiplexing enzyme-based metabolite quantification on a single chip, ultimately opening a pathway towards a personal metabolome machine