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.

Post-hydrogenation of low-pressure chemical vapour deposited amorphous silicon

Abstract: We have grown undoped and doped amorphous silicon (a-Si) by low-pressure chemical vapour deposition (LPCVD) from silane at 550 and . The samples were then post-hydrogenated in an RF hydrogen plasma. The material is characterized by measurement of conductivity, hydrogen content and the slope of the Urbach tail. The effect of fast thermal quenching on the conductivity is investigated and the thermal equilibrium temperature is measured for doped LPCVD a-Si.

A novel polysilicon based process for three terminal surface micromachined cantilever

Abstract: A three terminal cantilever beam can be used as a switch and also for material and process characterization. This paper deals with process optimization for its fabrication with surface micromachining steps compatible with standard integrated circuit manufacturing technology. The problems encountered in each step of fabrication and possible solutions are discussed in detail. The process makes extensive use of polysilicon deposited by Low Pressure Chemical Vapour Deposition for contacts, sacrificial oxide as well as the structural layer.

Knudsen force based double beam MEMS vacuum pressure sensor

Abstract: Knudsen forces are gas molecular forces, generated due to the presence of a thermal gradient between two surfaces in rarefied gas and can be effectively used for the measurement of low pressures. This work reports on a Knudsen force based micro electro mechanical systems low pressure sensor consisting of two stacked beams of polysilicon—one acting as a heater while the other as a sensor. The structure is fabricated using a double sacrificial layer surface micromachining process. The thermal gradient across the two stacked beams is induced by resistive heating of the heater beam. The effect of using two separate beams for heating and sensing has been investigated at different heater current and the results are compared with the existing works. The provision of two beams has resulted in the sensor functioning at very low pressure of less than 0.1 Pa with an improved sensitivity of 15.5 fF mPa−1.

Silicon/Porous Silicon composite membrane for high sensitivity pressure sensor

Abstract: Porous Silicon (PS) has many interesting and unique properties that make it a viable material in the field of MEMS. In this paper we investigate the application of PS in improving the sensitivity of bulk micromachined piezoresistive pressure sensors. A part of the silicon membrane thickness has been converted into PS by electrochemical etching in HF based electrolyte. The property of low Young’s modulus of PS and its dependence on porosity have been exploited in obtaining higher sensitivity compared to pressure sensors with single crystalline silicon membranes. The sensitivity is found to increase with the porosity and thickness of PS layer and these can be easily controlled by varying the PS formation parameters.

Design and Fabrication of a Micro-Mirror for Low-Resolution Spectroscopy

Abstract: A wide variety of MEMS micro-mirrors are being developed for various optical applications. One such application is Fourier transform spectroscopy (FTS). The design, process optimization, and fabrication of a micro-mirror for this application are presented. Large, nontilting displacements of mirrors are required to achieve high FTS resolution. Although, certain applications require lower resolution, the mirror still needs to be nontilting. In order to obtain this without using deep reactive ion etching (DRIE), the micro-mirrors were fabricated on silicon using bulk micromachining with wet chemical etching. This paper presents the process developed for fabrication of the mirror with the required specifications. In addition, results of the FTS experiments conducted with the micro-mirror will also be presented.

I and i

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 …

Electrostatic pull-in instability in MEMS/NEMS: A review

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.

Textbook of biochemistry with clinical correlations

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 …