S. K. Lahiri

Bio: S. K. Lahiri is an academic researcher from Indian Institute of Technology Kharagpur. The author has contributed to research in topics: Lithium niobate & Power dividers and directional couplers. The author has an hindex of 17, co-authored 54 publications receiving 795 citations. Previous affiliations of S. K. Lahiri include Indian Institutes of Technology.

Study of hydrophilicity and stability of chemically modified PDMS surface using piranha and KOH solution

Abstract: Successful realization of various BioMEMS devices demands effective surface modification techniques of PDMS elastomer. This paper presents a detailed report on a simple and cost effective approach for surface modification of PDMS films involving wet chemical treatment in two-step processes: primarily involving piranha solution followed by KOH dip to improve hydrophilicity and stability of PDMS surface. Chemical composition of the solution and surface treatment condition have been varied and optimized to significantly increase the surface energy. The effect of surface modification of the elastomer after wet chemical treatment is analyzed using contact angle measurement and FTIR-ATR study. PDMS surface treated in piranha solution with H2O2 and H2SO4 in the ratio of 2:3 followed by a dip in KOH solution for 15 min duration each, demonstrated a maximum reduction of contact angle to ∼27° as compared to untreated sample having a contact angle of ∼110°. The removal of hydrophobic methyl group from elastomer surface and subsequent hydrophilization of surface by wet chemical process was confirmed from FTIR-ATR spectra. This result is also supported by improved adhesion and electrical continuity of deposited aluminum metal film over the modified PDMS surface. Copyright © 2011 John Wiley & Sons, Ltd.

Properties of silicon dioxide films deposited at low temperatures by microwave plasma enhanced decomposition of tetraethylorthosilicate

Abstract: Silicon dioxide films have been deposited at low temperatures (200–250 °C) by microwave plasma enhanced decomposition of tetraethylorthosilicate (TEOS). The effects of the presence of oxygen in the discharge in film deposition rate, mechanism, and the physical properties of the films have been investigated. Structural characterization of the deposited films has been carried out by etch rate measurements, infrared transmission spectra, x‐ray photoelectron spectroscopy, Auger, and secondary ion mass spectrometry analyses. Films deposited using TEOS and oxygen have confirmed a density comparable to standard silane‐based low‐pressure chemical vapor deposition and plasma enhanced chemical vapor deposition oxides, nearly perfect stoichiometry, extremely low sodium and carbon content, and the absence of many undesirable hydrogen related bonds. Various electrical properties, viz., resistivity, breakdown strength, fixed oxide charge density, interface state density, and trapping behavior have been evaluated by the...

Silicon MEMS vaporizing liquid microthruster with internal microheater

Abstract: This paper reports a silicon MEMS vaporizing liquid microthruster (VLM) with an internal p-diffused microheater. The device fabrication and testing have been briefly described. The VLM consisting of two micromachined, bonded silicon chips produces thrusts in the range of 5 µN to 120 µN with a heater power of 1 W to 2.4 W at a water flow rate of 1.6 µl s−1 using an exit nozzle of throat size 30 µm × 30 µm. A maximum thrust of 120 µN was produced with a heater power of 2 W at a water flow rate of 0.7 µl s−1 with exit nozzle of throat size 50 µm × 50 µm. The measurement has been carried out using a sensitive cantilever and a laser based lamp-and-scale arrangement. The internal microheater is expected to yield a higher efficiency compared with the external microheater.

Cross-axis sensitivity reduction of a silicon MEMS piezoresistive accelerometer

Abstract: This paper presents realization of a MEMS piezoresistive single axis accelerometer using dual doped TMAH solution. The silicon micromachined structure consists of a heavy proofmass supported by four thin flexures and sandwiched between top and bottom glass plates. Boron diffused piezoresistors located near fixed points of the flexure are used for sensing the developed stress due to applied acceleration. Based on the initial results an improved design has also been considered to achieve reduced cross-axis sensitivity and nonlinearity. The fabricated sensor tested upto 13 g acceleration shows average sensitivity of 0.556 mV/g along normal to the proofmass plane. The measured cross-axis sensitivity was 3.272 μV/g for X-axis and 3.442 μV/g for Y-axis which is less than 1% of Z-axis sensitivity. Comparing two designs there was an improvement of 63% sensitivity along Y-axis for the design with flexures placed along the proofmass edges.

Lab-on-chip technologies: making a microfluidic network and coupling it into a complete microsystem : a review

Abstract: Microfluidics is an emerging field that has given rise to a large number of scientific and technological developments over the last few years. This review reports on the use of various materials, such as silicon, glass and polymers, and their related technologies for the manufacturing of simple microchannels and complex systems. It also presents the main application fields concerned with the different technologies and the most significant results reported by academic and industrial teams. Finally, it demonstrates the advantage of developing approaches for associating polymer technologies for manufacturing of fluidic elements with integration of active or sensitive elements, particularly silicon devices.

Aerogel-based thermal superinsulation: an overview

Abstract: This review is focused on describing the intimate link which exists between aerogels and thermal superinsulation. For long, this applied field has been considered as the most promising potential market for these nanomaterials. Today, there are several indicators suggesting that this old vision is likely to become reality in the near future. Based on recent developments in the field, we are confident that aerogels still offer the greatest potential for non-evacuated superinsulation systems and consequently must be considered as an amazing opportunity for sustainable development. The practical realization of such products however is time-consuming and a significant amount of R&D activities are still necessary to yield improved aerogel-based insulation products for mass markets.

Status and Potential of Lithium Niobate on Insulator (LNOI) for Photonic Integrated Circuits

Abstract: Lithium niobate on insulator (LNOI) technology is revolutionizing the lithium niobate industry, enabling higher performance, lower cost and entirely new devices and applications. The availability of LNOI wafers has sparked significant interest in the platform for integrated optical applications, as LNOI offers the attractive material properties of lithium niobate, while also offering the stronger optical confinement and a high optical element integration density that has driven the success of more mature silicon and silicon nitride (SiN) photonics platforms. Due to some similarities between LNOI and SiN, established techniques and standards can readily be adapted to the LNOI platform including a significant array of interface approaches, device designs and also heterogeneous integration techniques for laser sources and photodetectors. In this contribution, we review the latest developments in this platform, examine where further development is necessary to achieve more functionalities in LNOI integrated optical circuits and make a few suggestions of interesting applications that could be realized in this platform. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Integrated optical components utilizing long-range surface plasmon polaritons

Abstract: New optical waveguide technology for integrated optics, based on propagation of long-range surface plasmon polaritons (LR-SPPs) along metal stripes embedded in dielectric, is presented. Guiding and routing of electromagnetic radiation along nanometer-thin and micrometer-wide gold stripes embedded in polymer via excitation of LR-SPPs is investigated in the wavelength range of 1250-1650 nm. LR-SPP guiding properties, such as the propagation loss and mode-field diameter, are investigated for different stripe widths and thicknesses. A propagation loss of /spl sim/6 dB/cm, a coupling loss of /spl sim/0.5 dB (per facet), and a bend loss of /spl sim/5 dB for a bend radius of 15 mm are evaluated for 15-nm-thick and 8-/spl mu/m-wide stripes at the wavelength of 1550 nm. LR-SPP-based 3-dB power Y-splitters, multimode interference waveguides, and directional couplers are demonstrated and investigated. At 1570 nm, coupling lengths of 1.9 and 0.8 mm are found for directional couplers with, respectively, 4- and 0-/spl mu/m-separated waveguides formed by 15-nm-thick and 8-/spl mu/m-wide gold stripes. LR-SPP-based waveguides and waveguide components are modeled using the effective-refractive-index method, and good agreement with experimental results is obtained.