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Enakshi Bhattacharya

Bio: Enakshi Bhattacharya is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Silicon & Surface micromachining. The author has an hindex of 14, co-authored 80 publications receiving 873 citations. Previous affiliations of Enakshi Bhattacharya include Indian Institutes of Technology & Tata Institute of Fundamental Research.


Papers
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TL;DR: In this paper, the fabrication and testing of Si/PS composite membrane pressure sensors with MicroPS and MacroPS of varying porosity were discussed and the deformation of composite membranes measured up to 10 bar showed that it saturates at high pressure and is irreversible.
Abstract: Since porous silicon (PS) has a much lower Young's modulus than single crystalline silicon, Si/PS composite membranes deflect more and can be used to fabricate pressure sensors with improved sensitivity. However, PS has some drawbacks, like weaker structural stability and being more susceptible to humidity due to its large surface-to-volume ratio. We discuss the fabrication and testing of Si/PS composite membrane pressure sensors with MicroPS and MacroPS of varying porosity. For the same porosity, the composite membranes with Si/MicroPS show higher sensitivity than Si/MacroPS. The sensor output is linear and repeatable at pressures less than 1 bar. The deformation of composite membranes measured up to 10 bar showed that it saturates at high pressure and is irreversible. Composite membranes also exhibit higher offset voltage than single crystal silicon membranes, which could be attributed to the stress developed in the membrane during PS formation and subsequent processing. The composite membrane pressure sensors were packaged on TO 39 headers, and the effect of humidity and temperature variation were investigated.

8 citations

Journal ArticleDOI
TL;DR: In this article, the authors discuss roughening of the surface of polysilicon, which forms the structural layer in surface micromachining, by the formation of porous silicon and its effect on stiction.
Abstract: Stiction, or adhesion of components to one another, is a major failure mechanism in surface micromachined MEMS. In this paper we discuss roughening of the surface of polysilicon, which forms the structural layer in surface micromachining, by the formation of porous silicon and its effect on stiction. The adhesivity of the surface is investigated by measurements of contact angle and the roughness is measured by a surface profiler. Measurements to estimate stiction on surface micromachined cantilevers and accelerometers are reported.

8 citations

Proceedings ArticleDOI
21 Nov 2001
TL;DR: In this paper, a coupled electromechanical model is developed to determine the stiction force from the pull-in and pull-out voltages, which is based on I-V data with the possibility of automation.
Abstract: Stiction is a major failure mechanism during the operation of accelerometers and hence it is important to know the stiction force that the structures encounter during use. We explore the possibility of devising an electrical technique for the direct measurement of in use stiction force. We have designed and fabricated three terminal test structures to measure both vertical and horizontal in use stiction. The measurement is not visual and is based on I-V data with the possibility of automation in the future. The structure consists of cantilever beams of different lengths each with an actuating pad and a detection pad. We measure the pull in voltage applied to the actuating pad, V PI , required to bring the cantilever beam in contact with the detection pad and the pull out voltage, V PO , at which the contact is broken. Using the Finite Element tool, ANSYS, a coupled electromechanical model is developed to determine the stiction force from the pull-in and pull-out voltages. We discuss the measurements in terms of the advantages and the shortcomings. We also discuss the sensitivity of the model to various material and geometric parameters and to the accuracy of the measurement.

7 citations

Journal ArticleDOI
TL;DR: In this article, a windowless helium lamp is employed to assist chemical vapor deposition of hydrogenated amorphous silicon from disilane feedstock gas at a film growth rate greater than 200 A/min.
Abstract: A windowless helium lamp is employed to assist chemical vapor deposition of hydrogenated amorphous silicon from disilane feedstock gas at a film growth rate greater than 200 A/min. Material properties in this preliminary study are comparable to the best hydrogenated amorphous silicon (a‐Si:H) films produced by conventional bulk plasma CVD techniques. The amount of photoconductivity degradation under long‐time illumination is more than plasma‐deposited a‐Si‐H thin films. Photoconductivity as high as σp =4×10−4 (Ω cm)−1 has been obtained.

7 citations


Cited by
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[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

Journal ArticleDOI
TL;DR: This work reviews the status of the various nanostructure-based biosensors and use of the self-assembly techniques and nano-electromechanical systems (NEMS) in bios Sensors is discussed.

506 citations

Journal ArticleDOI
TL;DR: In this paper, a review of the pull-in phenomenon in electrostatically actuated MEMS and NEMS devices is presented, along with physical principles that have enabled fundamental insights into the pullin instability as well as pullin induced failures.
Abstract: Pull-in instability as an inherently nonlinear and crucial effect continues to become increasingly important for the design of electrostatic MEMS and NEMS devices and ever more interesting scientifically. This review reports not only the overview of the pull-in phenomenon in electrostatically actuated MEMS and NEMS devices, but also the physical principles that have enabled fundamental insights into the pull-in instability as well as pull-in induced failures. Pull-in governing equations and conditions to characterize and predict the static, dynamic and resonant pull-in behaviors are summarized. Specifically, we have described and discussed on various state-of-the-art approaches for extending the travel range, controlling the pull-in instability and further enhancing the performance of MEMS and NEMS devices with electrostatic actuation and sensing. A number of recent activities and achievements methods for control of torsional electrostatic micromirrors are introduced. The on-going development in pull-in applications that are being used to develop a fundamental understanding of pull-in instability from negative to positive influences is included and highlighted. Future research trends and challenges are further outlined.

442 citations

Journal ArticleDOI
TL;DR: This beautifully illustrated and well-written book, with an impressive array of authors, is aimed at both undergraduate and postgraduate level and emphasises the biochemistry of mammalian cells.
Abstract: Textbook of biochemistry with clinical correlations , 4th edn TM Devlin, ed pp xvii + 1186, illustrated Wiley-Liss, New York, 1997 £2995, hardback This beautifully illustrated and well-written book, with an impressive array of authors, is aimed at both undergraduate and postgraduate level As the editor states in the preface, it is not intended to be a compendium of biochemistry but rather emphasises the biochemistry of mammalian cells The first 22 chapters cover …

420 citations