D. Uttamchandani

University of Strathclyde, Glasgow, Scotland, United Kingdom

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Publications (235)239.56 Total impact

  • Andrew Reid · James F.C. Windmill · Deepak Uttamchandani
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    ABSTRACT: MEMS microphones inspired by Ormia ochracea are constrained by their reliance on the resonant behavior of the system, forcing designers to compromise the goal of high amplification of directional cues to operate across the audio range. Here we present an alternative approach, namely a system optimized for the maximum amplification of directional cues across a narrow bandwidth operating purely as a sound-localization sensor for wide-band noise. Directional sensitivity is enhanced by increasing the coupling strength beyond the ‘dual optimization’ point, which represents the collocation of a local maximum in directional sensitivity and a local minimum in non-linearity, compensating for the loss of the desirable linearity of the system by restricting the angular range of operation. Intensity gain achieved is 16.3dB at 10° sound source azimuth with a linear directional sensitivity of 1.6dB per degree, while linear directional sensitivity in phase difference gain shows a seven fold increase over the ‘dual optimization’ point of 8 degrees phase difference per degree change in azimuthal angle.
    No preview · Article · Dec 2015 · Procedia Engineering
  • Robert Blue · Deepak Uttamchandani
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    ABSTRACT: This paper examines the recent emergence of miniaturized optical fiber based sensing and actuating devices that have been successfully integrated into fluidic microchannels that are part of microfluidic and lab-on-chip systems. Fluidic microsystems possess the advantages of reduced sample volumes, faster and more sensitive biological assays, multi-sample and parallel analysis, and are seen as the de facto bioanalytical platform of the future. This paper considers the cases where the optical fiber is not merely used as a simple light guide delivering light across a microchannel, but where the fiber itself is engineered to create a new sensor or tool for use within the environment of the fluidic microchannel.
    No preview · Article · Oct 2015 · Journal of Biophotonics
  • Deepak Uttamchandani · Joyce Poon · Marc Sorel · Hiroshi Toshiyoshi

    No preview · Article · Jul 2015 · IEEE Journal of Selected Topics in Quantum Electronics
  • Anna Dudus · Robert Blue · Michele Zagnoni · George Stewart · Deepak Uttamchandani
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    ABSTRACT: We report an optofluidics-based variable optical attenuator (VOA) employing a tapered side-polished single-mode optical fiber attached to an electrowetting-on-dielectric (EWOD) platform. The side polishing of the fiber cladding gives access to the evanescent field of the guided mode, while the EWOD platform electrically controls the stepwise translation of a liquid droplet along the variable thickness polished cladding of the fiber. The penetration of the evanescent field into the droplet leads to tunneling of optical power from the fiber core to the droplet, from where it is radiatively lost. As a result of the variable cladding thickness, the position of the droplet along the length of the polished fiber determines the degree of penetration of the evanescent field into the droplet. The droplet position can be electrically changed; thus, controlling the optical power loss from the fiber. This approach has been used to demonstrate an optofluidic continuous-fiber VOA typically providing up to 26 dB of broadband attenuation in the 1550-nm transmission window, with a wavelength dependent loss less than 1.1 dB. In this paper, we present the theoretical modeling and experimental characterization of the system, discussing the influence of the design parameters on the performance of this VOA.
    No preview · Article · Jul 2015 · IEEE Journal of Selected Topics in Quantum Electronics
  • Alan Paterson · Ralf Bauer · Li Li · Walter Lubeigt · Deepak Uttamchandani
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    ABSTRACT: A bimorph varifocal micromirror actuated thermoelectrically by a Peltier element is reported. The single-crystal silicon micromirror is 1.2 mm in diameter with a centered 1-mm-diameter gold coating for broadband reflection. The actuation principle is capable of varying the micromirror temperature above and below the ambient temperature, which contributed to a 57% improvement in the addressable curvature range in comparison to previously reported electrothermal and optothermal actuation techniques for the device. Altering the device temperature from 10 °C to 100 °C provided a mirror surface radius of curvature variation from 19.2 to 30.9 mm, respectively. The experimental characterization of the micromirror was used as a basis for accurate finite-element modeling of the device and its actuation. Negligible optical aberrations are observed over the operating range, enabling effectively aberration-free imaging. Demonstration in an optical imaging system illustrated sharp imaging of objects over a focal plane variation of 212 mm.
    No preview · Article · Jul 2015 · IEEE Journal of Selected Topics in Quantum Electronics
  • Anna Duduś · Robert Blue · Deepak Uttamchandani
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    ABSTRACT: We report on the fabrication and characterization of a single-mode fiber variable optical attenuator (VOA) based on a ferrofluid shutter actuated by a magnetic field created by a low voltage electromagnet. We compare the performance of a VOA using oil-based ferrofluid, with one VOA using water-based 12 ferrofluid, and demonstrate broadband optical attenuation of up to 28 dB with polarization dependent 13 loss of 0.85 dB. Our optofluidic VOA has advantages over MEMS-based VOAs such as simple construction and the absence of mechanical moving parts.
    No preview · Article · Mar 2015 · Applied Optics
  • Robert Blue · Anna Dudus · Deepak Uttamchandani

    No preview · Article · Jan 2015 · IEEE Journal of Selected Topics in Quantum Electronics
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    Alan Paterson · Ralf Bauer · Caspar Clark · Deepak Uttamchandani · Walter Lubeigt
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    ABSTRACT: Active control of output power and transverse intensity profile of a continuous-wave Nd:YAG laser is reported. This was achieved by controlling the surface profile of an intracavity MEMS device through active tuning of its temperature.
    Full-text · Conference Paper · Nov 2014
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    Alan Paterson · Ralf Bauer · Caspar Clark · Deepak Uttamchandani · Walter Lubeigt
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    ABSTRACT: Active control of key laser output beam parameters, such as optical power and transverse intensity profile, of a continuous-wave (CW) Nd:YAG laser is reported. This was achieved by accurately controlling the surface profile of an intracavity MEMS micromirror through active control of its substrate temperature. An output power variation (>20%) and a significant modification of the transverse mode profile could be observed for a temperature variation of ~35 ⁰C.
    Full-text · Conference Paper · Aug 2014
  • A. Duduś · Robert Blue · Deepak Uttamchandani
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    ABSTRACT: We report a miniature variable optical attenuator employing a ferrofluid actuator/shutter combination located between lensed optical fibers. The VOA consists of an opaque, undiluted ferrofluid plug actuator inside a microfluidic channel. The ferrofluid plug position is translated by a variable magnetic field generated from a miniature electromagnet. The ferrofluid plug actuator in turn displaces a second oil-diluted ferrofluid plug acting as an optical shutter. The position of the shutter controls the optical power coupled between the input and output fibers.
    No preview · Conference Paper · Aug 2014
  • R. Blue · A. Duduś · M. Konstantaki · S. Pissadakis · D. Uttamchandani
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    ABSTRACT: We report a method of characterization and modification of the optical transmission properties of a double tilted Bragg grating structure by using a micro droplet translated on an electrowetting-on-dielectric platform. The droplet makes contact with the fiber cladding in the zone between the two gratings in the fiber. The change in optical transmission spectrum with droplet position was experimentally measured, and results are presented and discussed.
    No preview · Conference Paper · Aug 2014
  • A. Duduś · Robert Blue · Michele Zagnoni · George Stewart · D. Uttamchandani
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    ABSTRACT: We report a broadband variable optical attenuator employing a side-polished single-mode optical fiber placed on an electrowetting-on-dielectric (EWOD) platform. Both theoretical and experimental analysis have been carried out on this system. Experimentally, a maximum attenuation of 25 dB was obtained in the wavelength range between 1520 nm and 1560 nm. This compares to a predicted maximum theoretical attenuation of 28 dB.
    No preview · Conference Paper · Aug 2014
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    Ralf Bauer · Alan Paterson · Caspar Clark · Deepak Uttamchandani · Walter Lubeigt
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    ABSTRACT: The output behavior of a Nd:YAG solid-state laser actively Q-switched by a MEMS scanning micromirror is presented. Using a gold-coated micromirror, maximum average output powers of 50mW and pulse durations as short as 120ns were obtained with a dual beam output. This output pattern originates from a pulse emission when the micromirror is at an angle from the cavity axis. The temporal and spatial behavior of this laser was experimentally characterized and then modelled using a numerical simulation of the laser rate equations. Finally, prospects for power-scaling this MEMS-based Q-switch technique are demonstrated using a dielectric-coated micromirror, which led to average output powers of up to 650mW and pulse energies above 40µJ.
    Full-text · Article · Aug 2014 · IEEE Journal of Selected Topics in Quantum Electronics
  • Ralf Bauer · Li Li · Deepak Uttamchandani
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    ABSTRACT: This paper presents the investigation of a variable angular vertical comb-drive (AVC) actuated MEMS scanning micromirror, focusing on the influence of the initial comb offset on the dynamic scan characteristics. Continuous control of the fixed comb initial vertical offset is achieved using an electrothermal actuator integrated in the AVC. Electro-thermomechanical simulations and experiments of the AVC structure show good agreement, with the initial vertical offset of the fixed comb reducing theoretically from 10.8 mu m (0 mW to actuator) to 6.0 mu m (500 mW to actuator) and experimentally from 10.4 mu m (0 mW to actuator) to 4.9 mu m (510 mW to actuator). Experimentally, a change of the initial vertical comb-offset from 10.4 mu m to 4.9 m leads to a reduction of the measured dynamic total optical scan angle (TOSA) from 27 degrees to 19 degrees for 100 V ac actuation. In addition, a mechanically assisted deflection of the AVC actuators to achieve an almost in-plane comb configuration further reduces the measured dynamic TOSA to about 3 degrees. The overall device behavior is modeled using a hybrid simulation approach combining FEM analysis of the AVC capacitance with an analytical solution of the motion equation of the scanner. The analysis show good agreement, with the experimentally measured characteristics; overall showing an increased TOSA with higher initial comb offsets. [2013-0344]
    No preview · Article · Aug 2014 · Journal of Microelectromechanical Systems
  • A. Dudus · R. Blue · M. Zagnoni · G. Stewart · D. Uttamchandani
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    ABSTRACT: We report an in-line, fiber optic, broadband variable optical attenuator employing a side-polished, single-mode optical fiber integrated on a digital microfluidics platform. The system is designed to electrically translate a liquid droplet along the polished surface of an optical fiber using electrowetting forces. This fiber optic device has the advantage of no moving mechanical parts and lends itself to miniaturization. A maximum attenuation of 25 dB has been obtained in the wavelength range between 1520 nm and 1560 nm.
    No preview · Article · Jul 2014 · Applied Physics Letters
  • Anna Dudus · Robert Blue · Maria Konstantaki · Stavros Pissadakis · Deepak Uttamchandani
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    ABSTRACT: The use of digital electrowetting as a means of characterising and modifying the optical transmission properties of long-period gratings (LPGs) fabricated in boron-doped germanosilicate single-mode fibre is described. An electrowetting-based platform has been designed to move fluid droplets, of about 2 mu l volume, along the main axis of the LPG fibre. The droplets make contact with the cladding over the grating region of the fibre. Optical measurements are presented illustrating the tuning of the optical resonance wavelength of an LPG as the droplet advances stepwise along the fibre cladding under electrowetting-based actuation, and the increase of 53% in the LPG tuning range achieved by side polishing the grating section of the fibre.
    No preview · Article · Jun 2014 · Micro & Nano Letters
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    ABSTRACT: A microelectromechanical systems (MEMS)-based structure capable of operating mechanically as a directional acoustical sensor is presented. The structure, fabricated through the commercially available SOIMUMPS foundry process, consists of two circular discs attached to a central suspension beam, fixed at both ends. The design of the structure resembles other directional MEMS microphones that mimic the directional hearing organ of the parasitoid fly, Ormia ochracea. Modal analysis and mechanical acoustic directionality analysis using both laser Doppler vibrometry and finite element modelling have been implemented. It is demonstrated that this coupled MEMS structure exhibits an acoustic directional response, with a one-to-one relationship between the relative vibration amplitudes of the two coupled discs and the angle of sound, from -75° to +60°.
    Full-text · Article · Apr 2014 · Micro & Nano Letters
  • R. Blue · D. Uttamchandani
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    ABSTRACT: Glaucoma is an eye disease resulting from excess intraocular pressure (IOP) and affects millions worldwide; moreover, it gives very little warning sign, until vision is affected. A reliable technique for continuous monitoring of IOP has been long sought after. However, it took the advent of microelectromechanical systems (MEMS) technology to introduce a step change in the possibilities of miniaturization to truly open the door to such a possibility. This chapter tracks the major developments of the interdisciplinary effort to miniaturize the necessary components, such as low-power electronics, energy harvesting, wireless telemetry, and biocompatible materials to realize a fully autonomous IOP system.
    No preview · Article · Dec 2013
  • Anartz Unamuno · Robert Blue · Deepak Uttamchandani
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    ABSTRACT: We report on the modeling and testing of a Vernier latched MEMS variable optical attenuator (VOA) which uses chevron electrothermal microactuators to control fiber-to-fiber optical power coupling. The use of microlatches has the advantage of holding the mechanical position of the fiber, and therefore the level of attenuation, with no electrical energy supplied except only to change the attenuation. Results of analytical electro-thermo-mechanical models of the device are obtained and compared with experimental test results, showing a good agreement. A step resolution of 0.5 μm for this multi-state latched device is achieved using a Vernier latch approach. This incremental step size is smaller than previously reported latched microactuators. The VOA demonstrated an attenuation range of over 47 dB and an insertion loss of 1 dB. The wavelength dependent loss across the optical communications C-band is 1.4 dB at 40 dB attenuation and the 10-90% transition time of the unlatched VOA is measured to be 1.7 ms.
    No preview · Article · Oct 2013 · Journal of Microelectromechanical Systems
  • Euan J. Boyd · Li Li · Robert Blue · Deepak Uttamchandani
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    ABSTRACT: This paper reports on the measurement of the thermal coefficient of Young's modulus of both single crystal silicon and 3C silicon carbide over the temperature range spanning 200–290 K. The thermal coefficients were determined by monitoring the change of resonance frequency of micro-cantilevers as their temperature was reduced. The thermal coefficient of Young's modulus, 1/E · δE/δT was measured to be −52.6 ± 3.45 ppm/K for silicon and −39.8 ± 5.99 ppm/K for 3C silicon carbide, agreeing well with theoretical predictions, and also with experimental values that have been previously published for temperatures above 273 K. This work has therefore expanded the temperature range over which the thermal coefficient of Young's modulus has been measured to below 273 K and towards the temperatures required for low-temperature military and space applications.
    No preview · Article · Aug 2013 · Sensors and Actuators A Physical