54,206 research outputs found
Towards flexible asymmetric MSM structures using Si microwires through contact printing
This paper presents development of flexible metal-semiconductor-metal devices using silicon (Si) microwires. Monocrystalline Si in the shape of microwires are used which are developed through standard photolithography and etching. These microwires are assembled on secondary flexible substrates through a dry transfer printing by using a polydimethylsiloxane stamp. The conductive patterns on Si microwires are printed using a colloidal silver nanoparticles based solution and an organic conductor i.e. poly (3,4-ethylene dioxthiophene) doped with poly (styrene sulfonate). A custom developed spray coating technique is used for conductive patterns on Si microwires. A comparative study of the currentāvoltage (IāV) responses is carried out in flat and bent orientations as well as the response to the light illumination of the wires is explored. Current variations as high as 17.1 Ī¼A are recorded going from flat to bend conditions, while the highest I on/I off ratio i.e. 43.8 is achieved with light illuminations. The abrupt changes in the current response due to light-on/off conditions validates these devices for fast flexible photodetector switches. These devices are also evaluated based on transfer procedure i.e. flip-over and stamp-assisted transfer printing for manipulating Si microwires and their subsequent post-processing. These new developments were made to study the most feasible approach for transfer printing of Si microwires and to harvest their capabilities such as photodetection and several other applications in the shape of metal-semiconductor-metal structures
Self-assembled granular walkers
Mechanisms of locomotion in microscopic systems are of great interest not
only for technological applications, but also for the sake of understanding,
and potentially harnessing, processes far from thermal equilibrium.
Down-scaling is a particular challenge, and has led to a number of interesting
concepts including thermal ratchet systems and asymmetric swimmers. Here we
present a system which is particularly intriguing, as it is self-assembling and
uses a robust mechanism which can be implemented in various settings. It
consists of small spheres of different size which adhere to each other, and are
subject to an oscillating (zero average) external force eld. An inherent
nonlinearity in the mutual force network leads to force rectication and hence
to locomotion. We present a model that accounts for the observed behaviour and
demonstrates the wide applicability and potential scalability of the concept.Comment: 17 pages, 4 figure
Reconfigurable wideband patch antenna for cognitive radio
Cognitive radio communication is envisaged to be a new paradigm of methodologies for enhancing the performance of radio communication systems through the efficient utilization of radio spectrum. A key enabler for realization of a cognitive communication system is the capability of re-configurability in the underlying hardware and the associated protocol suite. Reconfigurable double C-Slot microstrip patch antenna fed by 50 ohm microstrip line is proposed in this paper. The frequency tuning is performed by switching on and off two patches. The antenna can operate in dual-band or in very wide band mode in 5, 6 and 7
GHz bands. The wide-band mode can be obtained when both switches are in the ON state with impedance bandwidth of 33.52
% from 4.99 to 7 GHz. The total size of the ground plane is 50 x 50 mm2. The proposed antenna verified through both numerical
simulation and measurement of an experimental prototype. The antenna achieves a gain of 5 to 8 dBi and radiation efficiency
about 80%
A Non-Scaling FFAG Gantry Design for the PAMELA Project
A gantry is reĀquired for the PAMELA proĀject using non-scalĀing Fixed Field AlĀterĀnatĀing GraĀdiĀent (NS-FFAG) magĀnets. The NS-FFAG prinĀciĀple ofĀfers the posĀsiĀbilĀiĀty of a gantry much smallĀer, lighter and cheapĀer than conĀvenĀtionĀal deĀsigns, with the added abilĀiĀty to acĀcept a wide range of fast changĀing enĀerĀgies. This paper will build on preĀviĀous work to inĀvesĀtiĀgate a deĀsign which could be used for the PAMELA proĀject
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