[show abstract][hide abstract] ABSTRACT: SCUBA-2 is an innovative 10000 pixel bolometer camera operating at
submillimetre wavelengths on the James Clerk Maxwell Telescope (JCMT). The
camera has the capability to carry out wide-field surveys to unprecedented
depths, addressing key questions relating to the origins of galaxies, stars and
planets. With two imaging arrays working simultaneously in the atmospheric
windows at 450 and 850 microns, the vast increase in pixel count means that
SCUBA-2 maps the sky 100-150 times faster than the previous SCUBA instrument.
In this paper we present an overview of the instrument, discuss the physical
characteristics of the superconducting detector arrays, outline the observing
modes and data acquisition, and present the early performance figures on the
telescope. We also showcase the capabilities of the instrument via some early
examples of the science SCUBA-2 has already undertaken. In February 2012,
SCUBA-2 began a series of unique legacy surveys for the JCMT community. These
surveys will take 2.5 years and the results are already providing complementary
data to the shorter wavelength, shallower, larger-area surveys from Herschel.
The SCUBA-2 surveys will also provide a wealth of information for further study
with new facilities such as ALMA, and future telescopes such as CCAT and SPICA.
[show abstract][hide abstract] ABSTRACT: Piezoelectric actuators are widely utilised in adaptive optics to enable mirrors having an actively controlled reflective
surface for the purpose of the wavefront correction by reducing the effects of rapidly changing optical distortion. Two new
prototype adaptive X-ray optical systems are under development with the aim of approaching the fundamental diffraction limit.
One proposed technology is microstructured optical arrays (MOAs) involving two or four piezoelectric strips bonded to a silicon
wafer to produce a micro-focused X-ray source for biological applications, and which uses grazing incidence reflection through
consecutive aligned arrays of channels obtained using deep silicon etching. Another technology is large scale optics which
uses a thin shell mirror bonded with 20–40 piezoelectric actuators for the next generation of X-ray telescopes with an aim
to achieve a resolution greater than that currently available by Chandra (0.5"). PZT-based piezoelectric actuators are being
developed in this programme according to the design and implementation of the proposed mirror and array structures. Viscous
plastic processing is chosen for the preparation of the materials system, which is subsequently formed and shaped into the
suitable configurations. Precise controls on the thickness, surface finish and the curvature are the key factors to delivering
satisfactory actuators. Unimorph type piezoelectric actuators have been proposed for the applications and results are presented
regarding the fabrication and characterisation of such piezo-actuators, as well as the related design concepts and comparison
to modelling work.
Journal of Electroceramics 04/2012; 27(1):1-6. · 1.14 Impact Factor
[show abstract][hide abstract] ABSTRACT: Characterization methods for grazing-incidence reflecting channel arrays are discussed. Characterization of single-reflection, unactuated micro-structured optical arrays is required to evaluate their performance as focusing elements. Numerical simulations allow the contribution of the x-rays reflected by the channel walls to be distinguished from the overall transmitted signal, and are applied to axial sources. Experimental results are also shown to support the simulations by translation of the channel structure parallel to a detector plane, allowing separation of reflected and transmitted x-rays through the array on the detector.
[show abstract][hide abstract] ABSTRACT: A protein microarray hybridisation system has been implemented by employing patterned hydrophobic thin films on hydrophilic substrates as a means of confinement for aqueous samples. This approach has the ability to handle, and keep separate, small sample volumes of just a few microlitres. In addition, the system is more straightforward to use than the existing multi-well gasket solution. The paper describes the fabrication method and the system is demonstrated for a model protein microarray assay.
[show abstract][hide abstract] ABSTRACT: This paper describes two fabrication techniques-dry and wet etching for microstructured optical arrays (MOAs). The MOAs consist of arrays of channels deep etched in silicon. They use grazing incidence reflection to focus the X-rays through the consecutive aligned arrays of channels, ideally reflecting once off a vertical and smooth channel wall in each array. The MOAs were proposed by the Smart X-ray Optics (SXO) programme as small scale optics for micro-probing of biological cells and tissues. The first fabrication method requires inductively coupled plasma (ICP) using Bosch processes. The second one involves etching 〈110〉 silicon wafers in alkaline solutions.
[show abstract][hide abstract] ABSTRACT: This paper presents details of the design and fabrication of test structures specifically designed for the characterisation of two distinct digital microfluidic technologies: Electro-Wetting On Dielectric (EWOD) and Surface Acoustic Wave (SAW). A test chip has been fabricated that includes structures with a wide range of dimensions and provides the capability to characterise enhanced droplet manipulation as well as other integrated functions. In particular, we detail the use of EWOD to anchor droplets while SAW excitation is applied to perform mixing.
Microelectronic Test Structures (ICMTS), 2010 IEEE International Conference on; 04/2010
[show abstract][hide abstract] ABSTRACT: The UK Smart X-Ray Optics (SXO) programme is developing active/adaptive optics for terrestrial applications. One of the technologies proposed is microstructured optical arrays (MOAs), which focus X-rays using grazing incidence reflection through consecutive aligned arrays of microscopic channels. Although such arrays are similar in concept to polycapillary and microchannel plate optics, they can be bent and adjusted using piezoelectric actuators providing control over the focusing and inherent aberrations. Custom configurations can be designed, using ray tracing and finite element analysis, for applications from sub-keV to several-keV X-rays, and the channels of appropriate aspect ratios can be made using deep silicon etching. An exemplar application will be in the microprobing of biological cells and tissue samples using Ti Kα radiation (4.5 keV) in studies related to radiation-induced cancers. This paper discusses the optical design, modelling, and manufacture of such optics.
[show abstract][hide abstract] ABSTRACT: This paper details the first reported integration of two advanced digital microfluidic technologies where 100 mum silicon cubes are transported with electrowetting on dielectric (EWOD) and the droplet then held with EWOD while the silicon cubes are mixed with another liquid using a surface acoustic wave (SAW). Together these two technologies provide a comprehensive lab-on-a-chip combination with well developed functionalities. These include droplet generation, splitting and transportation offered by EWOD with transportation, mixing and biosensing being potentially available with SAW. The fabrication of both EWOD and SAW structures on LiNbO<sub>3</sub> substrates used low temperature Ta/Ta<sub>2</sub>O<sub>5</sub>/CYTOP layer deposition and patterning technologies, which enabled efficient transportation and mixing functions to be demonstrated.
Solid State Device Research Conference, 2009. ESSDERC '09. Proceedings of the European; 10/2009
[show abstract][hide abstract] ABSTRACT: This paper describes reflective adaptive/active optics for applications including studies of biological radiation damage. The optics work on the polycapillary principle, but use arrays of channels in thin silicon. For optimum performance the x-rays should reflect once off a channel wall in each of two successive arrays. This reduces aberrations since then the Abbe sine condition is approximately satisfied. Adaptivity is achieved by flexing the arrays via piezo actuation, providing further aberration reduction and controllable focal length.
Journal of Physics Conference Series 09/2009; 186(1):012067.
[show abstract][hide abstract] ABSTRACT: The UK Smart X-Ray Optics consortium is developing novel reflective
adaptive/active x-ray optics for small-scale laboratory applications,
including studies of radiation-induced damage to biological material.
The optics work on the same principle as polycapillaries, using
configured arrays of channels etched into thin silicon, such that each
x-ray photon reflects at most once off a channel wall. Using two arrays
in succession provides two reflections and thus the Abbe sine condition
can be approximately satisfied, reducing aberrations. Adaptivity is
achieved by flexing one or both arrays using piezo actuation, which can
provide further reduction of aberrations as well as controllable focal
lengths. Modelling of such arrays for used on an x-ray microprobe, based
on a microfocus source with an emitting region approximately 1μm in
diameter, shows that a focused flux approximately two orders of
magnitude greater than possible with a zone plate of comparable focal
length is possible, assuming that the channel wall roughness is less
than about 2nm.
[show abstract][hide abstract] ABSTRACT: The Smart X-ray Optics (SXO) programme is developing advanced
active-adaptive optics for X-rays. There are two main themes: large
optics for applications in astronomy and small scale optics for
micro-probing of biological cells and tissue samples using Ti or Cr
Kα radiation (4.5keV and 5.4keV, respectively) in studies related
to radiation induced cancers. For the latter objective, microstructured
optical arrays (MOAs) have been proposed. These consist of an array of
channels deep etched in silicon. They use grazing incidence reflection
to focus the X-rays through consecutive aligned arrays of channels,
ideally reflecting once off a channel wall in each array. Bending the
arrays allows variable focal length. The adaptivity is achieved by
flexing the arrays using PZT (Lead Zirconate Titanate)-based piezo
actuators. The array bending has been modelled using finite element
analysis (FEA) and the results showed that for reasonable efficiency,
the wall roughness of the channels should not exceed 2nm. This paper
describes two techniques of fabrication the MOAs: dry etching and wet
etching. The first method requires a special equipment called
"inductively coupled plasma" (ICP) using Bosch processes that are
designed to produce features with a high aspect ratio with vertical
walls. The second method involves using an alkaline solution for etching
<110> silicon wafers. This type of wafer was selected because of
the large wet etch ratio between the (111) and (100) planes that leads
to smooth vertical walls. For our application tetra-methyl-ammonium
hydroxide (TMAH) was used as it is fully compatible with CMOS integrated
[show abstract][hide abstract] ABSTRACT: A silicon swimming robot or pond skating device has been demonstrated. It floats on liquid surfaces using surface tension and is capable of movement using electrowetting on dielectric (EWOD) based propulsion. Its dimensions are 6 × 9 mm and the driving mechanism involves first trapping air bubbles within the liquid onto the hydrophobic surface of the device. The air bubbles are then moved using EWOD, which provides the propulsion. The device employs a recently reported EWOD technology enabling a driving voltage of ≈15 V, which is low enough for RF power transmission, thus facilitating wire-free movement. A wired version has been measured to move 1.35 mm in 168 ms (a speed of 8 mm s−1). This low voltage-EWOD (<15 V) device, fabricated using a CMOS compatible process, is believed to be the world’s smallest swimming MEMS device that has no mechanical moving parts. The paper also reports results of EWOD droplet operation driven by wireless power transmission and demonstrates that such a wireless design can be successfully mounted on a floating EWOD device to produce movement.
[show abstract][hide abstract] ABSTRACT: This paper presents test structures designed for studying the relationship between the operating voltage and different electrode configurations and areas for coplanar electrowetting on dielectrics (EWOD) devices. New test structures have been designed and fabricated using anodic Ta<sub>2</sub>O<sub>5</sub> dielectric and thin aFP (amorphous Fluoropolymer CYTOP from Asahi Glass Co., Ltd.). These test structures have been used to characterize the contact angle change, which is between 114deg and 81deg with an applied voltage of less than 20 V. This demonstrates that by modifying the coplanar architecture, the operating voltage can be reduced by a factor of two, compared to previously reported coplanar EWOD structures. Droplet manipulation on a coplanar EWOD system with this new design has been successfully demonstrated, with a driving voltage of 15 V.
IEEE Transactions on Semiconductor Manufacturing 03/2009; · 0.86 Impact Factor
[show abstract][hide abstract] ABSTRACT: This paper presents a robust anodic Ta<sub>2</sub>O<sub>5</sub> dielectric as an alternative insulator for fabricating low-voltage electrowetting on dielectric (EWOD) systems. Previously reported low-voltage EWOD technologies require high-temperature processes ( > 435degC), which unlike this room temperature technology, are not compatible with standard copper and aluminum integrated circuit interconnect technology as well as polymer-based substrates. The anodized Ta<sub>2</sub>O<sub>5</sub> forms a uniform pinhole free layer with a surface roughness ( R <sub>a</sub>) of 0.6 nm. This robust film enables an ultrathin amorphous FluoroPolymer layer to be employed to reduce the EWOD driving voltage to 13 V. Both sub-20-nm Teflon-AF and CYTOP layers have been successfully coated on top of Ta<sub>2</sub>O<sub>5</sub> with good adhesion. Applying voltages of 6-15 V significantly modified the contact angles of droplets in air on these samples (121deg to 81deg on Teflon-AF at 13 V and 114deg to 95deg on CYTOP at 6 V). Successful 14-V EWOD manipulation involving droplets being dispensed from a reservoir, their movement, followed by merging them together has been demonstrated using devices using a Teflon-AF + Ta<sub>2</sub>O<sub>5</sub> dielectric.
Journal of Microelectromechanical Systems 01/2009; · 2.13 Impact Factor
[show abstract][hide abstract] ABSTRACT: This paper presents test structures designed for studying the relationship between the operation voltage and the configuration of electrode area for coplanar EWOD (Electro Wet- ting On Dielectrics) devices. Robust anodic Ta<sub>2</sub>O<sub>5</sub> dielectric and thin aFP (amorphous Fluoropolymer) have been used to fabricate the structures. Test structures have been used to characterise the significant contact angle change on asymmetric configurations, 114deg to 81deg on CYTOP (amorphous fluoropolymer from Asahi Glass Co. Ltd.) with an applied voltage of less than 20 V. This demonstrates that by modifying the design, the operating voltage can be reduced by a factor of two, compared to the existing symmetric coplanar EWOD structures. Droplet manipulation on a coplanar EWOD system with this new design has been successfully demonstrated, with a driving voltage of 15 V.
Microelectronic Test Structures, 2008. ICMTS 2008. IEEE International Conference on; 04/2008
[show abstract][hide abstract] ABSTRACT: This paper reports a CMOS compatible fabrication procedure that enables electrowetting-on-dielectric (EWOD) technology to be post-processed on foundry CMOS technology. With driving voltages less than 15 V it is believed to be the lowest reported driving voltage for any material system compatible with post-processing on completed integrated circuits wafers. The process architecture uses anodically grown tantalum pentoxide as a pinhole free high dielectric constant insulator with an overlying 16 nm layer of Teflon-AF®, which provides the hydrophobic surface for droplets manipulation. This stack provides a very robust dielectric, which maintains a sufficiently high capacitance per unit area for effective operation at a reduced voltage (15 V) which is more compatible with standard CMOS technology. The paper demonstrates that the sputtered tantalum layer used for the electrodes and the formation of the insulating dielectric can readily be integrated with both aluminium and copper interconnect used in foundry CMOS.
[show abstract][hide abstract] ABSTRACT: Optical fibre pressure sensors have potential performance advantages over electrical sensors in measuring rapid transients such as shock waves from explosive blasts. We report the development of micromachined optical fibre Fabry–Pérot pressure sensors using a silicon dioxide or nitride diaphragm and detail the fabrication stages of the sensor body and diaphragm. The planar technology used is based on silicon deep etching and direct fusion bonding of silicon wafers. Test results for both types of diaphragm are presented. Sensors with rise times better than 3 µs, range 0.1 to 1 MPa and resolution ~500 Pa have been demonstrated in explosives trials. Despite the difference in the sign of stress for the two diaphragm types, both demonstrated excellent high-speed response to explosively generated air shocks.
Journal of Micromechanics and Microengineering 06/2007; 17(7):1334. · 1.79 Impact Factor