Molecular diagnostic tools need to be capable of detecting specific biomolecules that serve as an indicator for a disease state, ideally in a robust and easy to use format, enabling implementation as a point-of-care device. As sample collection should be minimally invasive and not require specific medical expertise or qualifications, blood fingerprick samples (~20 õL) are particularly attractive. Nanoscale field effect transistors are being explored as disposable point-of-care molecular diagnostic devices in the TSB/EPSRC-funded project "Low cost nanowire diagnostic platform" (see link below). However, nanoFET assays require a low, 1 mM or less, salt concentration to avoid Debye screening of antibody-bound analyte molecules and hence require a sample preparation step. For nanoFET analysis of blood biomarkers, this cannot be achieved by dilution of the sample because this could result in biomarker concentrations below the detection limit of the assay. In this project we are developing a simple dialysis cell which can remove a desired amount of salt by adjustment of the sample and water flow rates, while biomarkers with a molecular weight exceeding a set threshold value are retained. The cell is based on a cross-flow dialysis configuration with millifluidic channels on both sides of a track-etched membrane, enabling low sample volumes as required for fingerprick blood samples.
CREATIF provides the CCI with a creative experience collaborative tool consisting of intuitive software design tools coupled to a digital dispenser printer allowing them to create bespoke smart fabrics by printing. The design tools consist of software to collaboratively design, layout, visualise and simulate smart fabrics which are then produced using a dispenser printer; conventional fabrics are functionalised by printing active electronic inks. 'Visualisation' and simulation will interact in the collaborative design process with the senses of sight (through a monitor image), hearing (through Skype and by the smart fabric function of sound emission from the PC speakers) and touch (through the use of touch screens for design and the simulation of the feel of the fabric and the feeling of being touched on a haptic PC screen).
CREATIF offers to the CCI the ability to transform everyday fabrics into knowledge intensive smart fabric based creations incorporating a high level of intellectual creative content, by mass customisation of basic templates, or in one off designs.
The consortium consists of a design software developer (Grafixoft), a university specialised in fabric machine design (University of Aachen), a university with world leading expertise in creating smart fabrics by printing (University of Southampton), a creative design SME (Diffus Design), an SME, active in design-led building structures and architecture (Base Structures), a large company active in architecture and creative design (Zaha Hadid) and an SME specialised in advanced inkjet printers (Ardeje). We demonstrate the creative experience tools use in a real environment by producing, within CREATIF, three advanced smart fabric prototypes (for interactive light emission, interactive colour change and sound emission/touch) and apply them in two applications relevant to the CCI: an interactive, modular blind and exhibition stand. These directly target the CCI of design, advertising and architecture although the collaborative tool impacts any CCI using fabrics.
White blood cells play a central role in the bodyââ¬â¢s defence against bacterial, viral and fungal pathogens. In blood, there is only one white blood cell for every 1000 red blood cells, which makes their isolation a difficult task. Conventional isolation methods such as membrane filtration, differential centrifugation, or selective lysis of red blood cells could result in altered immune-phenotype or impaired viability of isolated WBCs and require a relatively large volume of blood.
In this project we have developed a microfluidic system with hydrodynamic cell traps that selectively capture white blood cells while not obstructing the flow path for red blood cells and platelets. The traps and therefore the immobilized cells are optically accessible, presenting an array of leukocytes that can be studied, at a sub-cellular level, with conventional biochemical labelling methods.
Whilst cell arrays are of general interest for cell population heterogeneity studies, e.g. different responses to external stimuli, our initial focus is on establishing nanoparticle association and uptake for different white blood cell types, identified by antibody labelling of distinct membrane receptors.
The project concerns the fabrication of low optical loss polysilicon waveguides deposited using Hot-Wire Chemical Vapour Deposition (HWCVD) at a temperature of 240C. A polysilicon film of 220 nm thick was deposited on top of a 2000 nm thick PECVD silicon dioxide. The crystalline volume fraction of the polysilicon film was measured by Raman spectroscopy to be 91%. The optical propagation losses of 400, 500, and 600 nm waveguides were measured to be 16.9, 15.9, and 13.5 dB/cm, respectively, for transverse electric (TE) mode at the wavelength of 1550 nm.
The emerging field of helium ion microscopy (HIM) is rapidly establishing itself as a valuable surface imaging technique, capable of generating images exhibiting sub-nm resolution and a high depth of field, surpassing that possible with scanning electron microscopy (SEM). This is enabled by the atomically sharp helium ion source and the larger momentum (and so shorter de Broglie wavelength) of helium ions compared to electrons, which together result in a sub-nm probe focused on the sample and a low beam divergence angle. The combination of a small probe size and the low energy of the secondary electrons (SE) generated through the interaction of the helium beam with the sample leads to a small interaction volume and hence enables high resolution imaging of the sample surface. Our Orion at Southampton is capable of an edge resolution of 0.35 nm (a good field emission gun SEM achieves approximately 1 nm). A microchannel plate can be inserted to collect the back-scattered helium ions, forming images that compliment those created by the SE detector, and provide more materials contrast. The system is also fitted with an integrated electron flood gun for charge neutralization which allows insulating samples to be imaged without the application of a conductive coating. Furthermore, the large depth of field can be exploited with stereo imaging techniques to extract 3D information from a sample.
In addition to its imaging capabilities, the focused beam of helium ions generated by the HIM can also used be used for nanofabrication through the direct modification and patterning of material, analogous to the way in which the gallium ion beam is used in focused ion beam (FIB) systems. The smaller probe size in the HIM enables the definition of finer patterns and more controlled milling than with a Ga FIB, with less damage to the surrounding material. A gas injection system also provides the capability for beam induced deposition of metals in well-defined patterns.
Here at Southampton, we are developing both imaging and nanofabrication applications for the helium ion microscope. Examples of these include:
- The imaging of biological micro and nano structures such as those found on the wing scales of lepidoptera (butterflies and moths), which are responsible for the vivid colouration and remarkable optical effects observed in these creatures. Charge neutralization with the flood-gun together with the high resolution and large depth of field provided by the HIM is allowing the fine details on these structures to be imaged clearly for the first time [1].
- Ion induced luminescence spectroscopy with the Gatan MonoCL system, including tests on materials known to exhibit cathodoluminescence in the visible- near IR range, e.g. quantum dots, fluorescent dyes, and rare-earth doped nanocrystals. The aim is to image biological samples tagged with luminenscent species to a resolution beyond that which is possible with cathodoluminescence in an SEM [2].
- The fabrication by direct milling of nanoelectronic devices in materials such as extremely thin silicon-on-insulator and graphene. The technique enables the rapid prototyping of structures such as quantum point contacts, nanowires, side-gated transistors and quantum dot devices in novel thin materials for next-generation computing [3].
- The characterization of the nanoscale chemical variations in polymeric semiconductor thin-film blends being developed for organic solar cells [4].
[1] S. A. Boden, A. Asadollahbaik, H. N. Rutt, and D. M. Bagnall, ââ¬ÅHelium ion microscopy of Lepidoptera scales.,ââ¬? Scanning, vol. 33, pp. 1-14, Jul. 2011.
[2] S. A. Boden, T. M. W. Franklin, L. Scipioni, D. M. Bagnall, and H. N. Rutt, ââ¬ÅIonoluminescence in the helium ion microscope,ââ¬? Microscopy and Microanalysis 18, 1253-1262 (2012).
[3] S. A. Boden, Z. Moktadir, D. M. Bagnall, H. Mizuta, and H. N. Rutt, ââ¬ÅFocused helium ion beam milling and deposition,ââ¬? Microelectronic Engineering, vol. 88, pp. 2452-2455, Nov. 2011.
[4] A. J. Pearson, S. A. Boden, D. M. Bagnall, D. G. Lidzey, and C. Rodenburg, ââ¬ÅImaging the bulk nanoscale morphology of organic solar cell blends using helium ion microscopy.,ââ¬? Nano letters, vol. 11, no. 10, pp. 4275-81, Oct. 2011.
Single electron transistors (SET) are indispensible devices for quantum information processing and our Si based SETs have several advantages like high integration densities, low cost, and long spin decoherence time. We will further develop the technologies towards the practical implementation to the industry by optimising the fabrication process technologies in Southampton Nanofabrication Centre and examining them in the world leading low temperature measurement facilities. Especially, we will develop Si based SETs defined by the atomically flat interfaces to achieve the robust design capabilities against the interfacial defects and surface roughness, which are important for scalabilities and mass production.
Thermoelectric generators (TEGs) are devices that convert heat into electricity. They are very attractive energy harvesters because they are highly reliable and environment-friendly. The efficiency of thermoelectric generators depends on the temperature gradient across the device, the average temperature of operation, and on the thermoelectric properties of the material. Most work on improving the TEG efficiency deals with improving the thermoelectric properties of the material. In this work, we propose a method of improving the efficiency of the TEG by increasing the temperature gradient across the device. To accomplish this, a lens can be used to concentrate solar radiation on the membrane of the TEG. By focusing solar radiation, the input heat flux increases; the temperature gradient across the device also increases; and the efficiency of the TEG improves as well.
Many industries heavily rely upon advances in electronic devices. As development of electronics continues, new structures and new materials are being utilised. The reliability of these new technologies therefore need to meet the same high levels as the traditional technologies that they are replacing.
Industries such as space and nuclear in particular, face an additional challenge affecting the reliability of their electrical devices; radiation. Ionizing radiation in particular can damage dielectric layers in devices such as metal-oxide-semiconductor (MOS) transistors and resistive memories. In either case, controlling the radiation effects of dielectrics is essential for the reliability of these devices.
High-k MOS capacitors have been fabricated, analysed and irradiated. TiN/HfOx/Si structures in particular showed superior properties in comparison with silicon dioxide stacks, including high capacitance with low leakage. The ionizing radiation results indicate the high-k metal gate structures are just as radiation hard as the silicon dioxide structures. This verifies the high-k metal gate structures can be used as a replacement for silicon dioxide gate oxides, enabling the scaling limit in CMOS industry to be overcome.
A variety of resistive memory cells are fabricated whereby the effects of the interfacial layers, electrodes and insulator are investigated. Electrochemical metallization memory cells switching kinetics are investigated whereby the switching mechanism is analysed. VCM and ECM radiation responses are also investigated.
Low Density Parity Check (LDPC) error correction codes have found application in numerous standards for both wired and wireless communication, including those for home networking, Local Area Networking (LAN), cellular systems, wireless LAN and Digital Video Broadcasting (DVB). LDPC codes enjoy near-optimal error correction performance, which facilitates communication throughputs that approach the capacity of the channel and meet the ever-increasing consumer demand for high-speed data. However, in order to realise these high communication throughputs, the LDPC encoder and decoder must have correspondingly-high processing throughputs. In order to facilitate the rapid prototyping of high-speed communication systems, there is a need for Field Programmable Gate Array (FPGA) realisations of LDPC decoders having high processing throughputs. While a throughput of 16.2 Gbps has already been achieved by the current state-of-the-art design, this is achieved by employing a fully-parallel architecture, which supports only a single LDPC matrix. Indeed, many more high-throughput FPGA LDPC architectures have been proposed in the literature, but each has its own drawbacks. These drawbacks may be manifested as relatively poor error correction performance, resource usage, energy consumption, latency, reconfigurability or LDPC matrix dimensions, for example. Hence, there is a need for generalised high-throughput FPGA architectures that can be configured to support not only various different LDPC matrices, but also various different trade-offs between the contradictory system characteristics listed above. Furthermore, there is a need for methodologies that allow the configuration of these architectures to be holistically designed, in order to readily achieve an appropriate trade-off between the characteristics. In this way, the resultant general purpose architectures would have significantly more applicability and commercial viability than existing high-throughput architectures.
During the past two decades, reliable wireless communication at near-theoretical-limit transmission throughputs has been facilitated by receivers that operate on the basis of the Bahl-Cocke-Jelinek-Raviv (BCJR) algorithm. Most famously, this algorithm is employed for turbo error correction in the Long Term Evolution (LTE) standard for cellular telephony, as well as in its previous-generation predecessors. However, the transmission throughput of these standards is limited by the processing throughput of the turbo decoder. This limit may be attributed to the data dependencies of the BCJR algorithm, resulting in an inherently serial nature that cannot be readily mapped to processing architectures having a high degree of parallelism. Against this background, this project will redesign turbo decoder implementations at an algorithmic level, rather than only at the architectural level, which is the State-Of-the-Art (SOA) approach. More specifically, we have devised an alternative to the BCJR algorithm, which has the same error correction capability, but does not have any data dependencies. Owing to this, our algorithm can be mapped to highly-parallel many-core processing architectures, facilitating an LTE turbo decoder processing throughput that is several times higher than the SOA, satisfying future demands for gigabit throughputs. In collaboration with ARM, Altera and BT, this research addresses key EPSRC priorities in the Information and Communication Technologies theme, including 'Many-core architectures and concurrency in distributed and embedded systems' and 'Towards an intelligent information infrastructure'.