INSTITUTE OF SMART STRUCTURES & SYSTEMS (ISSS)

The Journal of ISSS  [ISSN 2319–6408]

[Click on the paper title to download the fulltext]

Volume 4 Number 1 March-September 2015

Table of Contents

1

Editorial

2

In-situ structural integrity monitoring based on non-destructive testing principles [abstract] [full text]

3-17

Christian Boller, Gerd Dobmann, Eckhardt Schneider

Integrated circuit security: an overview [abstract] [full text]

18-37

Ange Marie P. Fievre, Al-Aakhir A. Rogers, Shekhar Bhansali

Impedance based structural health monitoring using serially connected piezoelectric sensors [abstract] [full text]

38-45

C. Bharathi Priya, N. Gopalakrishnan, A. Rama Mohan Rao

Study of stencil printing parameters for ball grid array formation at smaller pitch [abstract] [full text]

46-54

Shrikant G. Kulkarni, Varsha A. Chaware, Girish J. Phatak

Transduction of A0 Lamb mode using rotationally misaligned air-coupled probes in composite laminates [abstract] [full text]

55-60

C. Ramadas, Irfan Khan, Avinash S. Hood, Makarand Joshi

Complete development of a single cell PMUT transducer: design, fabrication, characterization, and integration [abstract] [full text]

61-69

Ajay Dangi, Amod Hulge, Anish Somasundaran, Rominus S. Valsalam, Rudra Pratap

The behaviour of continuous flow xenon difluoride etching of silicon [abstract] [full text]

70-75

D. Drysdale, A. O’Hara, C. H. Wang

Wind vibration energy harvesting through macro fiber composites: a probabilistic approach [abstract] [full text]

76-83

Abhishek Ghiya, A. Arockirajan, Sayan Gupta

 

Volume 3 Number 2 September 2014

 

MEMS based Integrated Gas Sensor for NO2 and NH3 [abstract] [full text]

1-6

Rahul Prajesh, Nishit Jain, V K Khanna, V. Gupta, Ajay Agarwal

 

Fabrication of Compliant Micro Grippers Using SU-8 with a Single Mask  [abstract] [full text]

7-13

Santosh D. B. Bhargav, Nikhil Jorapur, G. K. Ananthasuresh

 

Dynamic Response of Multiphase Magneto-Electro-Elastic Composites Subjected to Time-Harmonic Electric Excitation  [abstract] [full text]

14-20

B. Biju and K.Shankar

 

Preparation of a Silicon oil based Magneto Rheological Fluid and an Experimental Study of its Rheological Properties using a Plate and Cone Type Rheometer [abstract] [full text]

21-25

Shreedhar Kolekar, Rajashekar V. Kurahatti, Prashanth P.K, Vikram Kamble, Nitin Reddy

 

Analytical and Numerical Modeling of the Effect of Variable Flow Boundaries on the Squeeze Film Behavior in MEMS [abstract] [full text]

26-38

A. Roychowdhury, S. Patra, A. Nandy, R. Pratap

A Technology Overview and Applications of Bio-MEMS [abstract] [full text]

39-59

Nidhi Maheshwari, Gaurav Chatterjee, V. Ramgopal Rao

 

 

Volume 3 Number 1 March 2014

 

Molecular Dynamics Simulation of Residual Stress in a Si Quantum Dot Embedded in SiO2 [abstract] [full text]

1-7

Bhamy Maithry Shenoy, Gopalkrishna M. Hegde, and D. Roy Mahapatra

 

A Note on Modelling Directionality in Piezoresistivity [abstract] [full text]

8-17

Sreenath Balakrishnan, Kaustubh Deshpande, and G.K. Ananthasuresh

 

Low Frequency Vibration Energy Harvesting using Arrays of PVDF Piezoelectric Bimorphs  [abstract] [full text]

18-27

Rammohan S., Ramya C. M., Jayanth Kumar S., Anjana Jain, Rudra Pratap

 

Nanotextile Bio-sensors for Mobile Wireless Wearable Health Monitoring of Neurological and Cardiovascular Disorders [abstract] [full text]

28-77

Pratyush Rai, Sechang Oh, Prashanth Shyamkumar, Mouli Ramasamy, Robert E. Harbaugh and Vijay K. Varadan

 

 

 

Volume 2 Number 2 September2013

Ni30Ti50Pt20 High Temperature Shape Memory Alloy (HTSMA) Wires: Processing Related Issues  [abstract] [full text]

1-9

K.V. Ramaiah, C.N. Saikrishna, M. Sujata and S.K. Bhaumik

 

The Buckling of Metal Thin Films on Soft Elastomers: Use in Flexible Electronics [abstract] [full text]

10-17

Debashis Maji, Puneet Manocha, and Soumen Das

 

A Comparison of Burst Strength and Linearity of Pressure Sensors having Thin Diaphragms of Different Shapes  [abstract] [full text]

18-26

Vidhya Balaji and K.N. Bhat

 

Radio Frequency Micro Electro Mechanical Systems-An Overview [abstract] [full text]

27-75

Shiban K. Koul and Sukomal Dey

 

Announcement for ISSS Awards 2014 [webpage] [announcement]

76

 

 

Volume 2 Number 1 March 2013

 

From Editor’s Desk

 

Design and Development of a PDMS Membrane based SU-8 Micropump for Drug Delivery System [abstract] [full text]

Bidhan Pramanick, P. K. Dey, Soumen Das, T. K. Bhattacharyya

 

Digital Microfluidics and its Integration with a Fluidic Microreactor [abstract] [full text]

 

Paresh Kumar and Enakshi Bhattacharya

 

Turning Lamb mode based crack growth prediction for GIC determination in laminated composites [abstract] [full text]

C. Ramadas, Avinash Hood, Anoop Anand, Krishnan Balasubramaniam and Makarand Joshi

 

Fringe Field Junctionless FET as a Sensitive Displacement Sensor  [abstract] [full text]

 

Thejas, Navakanta Bhat, Rudra Pratap and K N Bhat

 

MEMS Pressure Sensors- An Overview of Challenges in Technology and Packaging [abstract] [full text]

 

K. N. Bhat and M. M. Nayak

 

 

 

Volume 1, Number 1, September 2012

 

President’s Message

 

From Editor’s Desk

 

Stiction Free Fabrication of MEMS Devices with Shallow Cavities Using a Two-Wafer Anodic Bonding Process [abstract] [full text]

1-9

K. Jayaprakash Reddy, K.N. Bhat, and Rudra Pratap

 

Low loss 2-port OADM using 1-D Photonic Crystal and 3-port Optical Circulator [abstract] [full text]

10-15

Renilkumar M and Prita Nair

 

Nanoscale Control of Electromigration for Resistance Tuning of Metal Lines [abstract] [full text]

16-21

Santanu Talukder, Arindam Ghosh and Rudra Pratap

 

FxLMS Algorithm with Feedback Neutralization for Active Vibration Control [abstract] [full text]

22-33

C.Karthikeyan and Shashikala Prakash

 

Feasibility Studies on MEMS Oxygen Flow Sensors by Differential Pressure Method for Pediatric Ventilators [abstract] [full text]

34-45

M.Rajavelu, D.Sivakumar, R.Joseph Daniel, K.Sumangala

 

Implementation of an Active Vibration Control Technique on a Full Scale Space Vehicle Structure [abstract] [full text]

46-54

Raja S, Janardhanam S, Shankar V, Balakrishnan B, Rekha K R and Asraff A K

 

Design, Fabrication and Characterization of RF MEMS Varactor for VCO Application [abstract] [full text]

55-64

Sukomal Dey, and Shiban.K. Koul

 

MEMS and Smart Systems Development: Indian Scenario [abstract] [full text]

65-84

V.K. Aatre

 

 

 

The Journal of ISSS

PAPER DETAILS & ABSTRACTS

[Click on the paper title to download the fulltext]

 

INSTITUTE OF SMART STRUCTURES & SYSTEMS (ISSS)

The Journal of ISSS  [ISSN 2319–6408]

Latest Issue of the Journal

The Journal of ISSS

PAPER DETAILS & ABSTRACTS

[Click on the paper title to download the full text]

Volume 4 Number 1 March-September 2015

1.

In-situ structural integrity monitoring based on non-destructive testing principles

Authors

Christian Boller, Gerd Dobmann, Eckhardt Schneider

Affiliation

Chair in Non-Destructive Testing and Quality Assurance (LZfPQ), Saarland University, Fraunhofer Institute for Nondestructive Testing IZFP,

Saarbrücken/Germany

Appears in

J. ISSS Vol. 4 No. 1, pp. 76-83, Mar - Sept. 2015.

Abstract

Nondestructive testing (NDT) is the major source of material and structural information to be obtained on a non-invasive basis where different physical principles are applied. This article specifically elaborates on acoustic and electromagnetic principles which have been used for stress as well as damage monitoring in materials and structures. Different successful application examples are described and discussed. A second part of the article then discusses the options those NDT techniques have in being used in the context of structural health monitoring (SHM) and what other sensing options have to be considered with SHM. The pros and cons of the different approaches are highlighted and the importance of numerical simulation for SHM systems is specifically underlined.

Keywords

Nondestructive testing, Structural health monitoring, Acoustics, Electromagnetism, Piezoelectric transducers, Electromagnetic transducers, Optical fibre sensing

 

2.

Integrated circuit security: an overview

Authors

Ange Marie P. Fievrea, Al-Aakhir A. Rogersb, Shekhar Bhansalia

Affiliation

aDept. of Electrical and Computer Engineering, Florida International University, Miami, FL

bDept. of Electrical Engineering, University of South Florida, Tampa, FL

Appears in

J. ISSS Vol. 4 No. 1, pp. 76-83, Mar - Sept. 2015.

Abstract

Integrated circuits security is surveyed. After the necessity of IC protection, different security classification systems are presented: degree of invasion, IBM levels, and FIPS 104-2 standards. A new classification is proposed, based on protection location (chip itself or package) and on protection aspect: anti-tamper or authentication. The main feature of each protection method is explained, advantages, drawbacks and current research challenges are discussed. It is concluded that security techniques should aim at satisfying the requirements of emerging technologies such as 3D Heterogeneous Systems on a Chip and wearable devices: compactness, anti-tamper and authentication.

Keywords

Integrated circuits, Security and protection, Anti tamper Authentication, Electronics packaging

 

3.

Impedance based structural health monitoring using serially connected piezoelectric sensors

Authors

C. Bharathi Priya, N. Gopalakrishnan, A. Rama Mohan Rao

Affiliation

CSIR – Structural Engineering Research Centre, Chennai

Appears in

J. ISSS Vol. 4 No. 1, pp. 76-83, Mar - Sept. 2015.

Abstract

The method of localised changes in Electro Mechanical Impedance (EMI) techniques with a cluster of piezoelectric (PZT) sensors, to detect damages is hastened in a serially connected LCR circuit under large-scale sensor deployment scenario. A heterogeneous material like concrete is utilised for technology demonstration of this novel scheme in structural health monitoring (SHM). Experiments are conducted on a concrete beam embedded with six PZT patches bonded on plates of increasing thickness by subjecting the beam to differential curing. ‘Serial sensing’ is used to in which the patches are connected in series and their admittance signatures are recorded from 10 kHz to 1000 kHz for different frequency ranges from day-2 to day-28. The frequency of admittance peaks of these patches are altered due to the plates of different thickness on which they are bonded. These frequency shifts are used to identify the contribution from individual patches from the serially obtained signatures. Using day-2 signature as baseline data, the variation in peak frequencies are observed and quantified using modified Root Mean Square Deviation (RMSD) as strength index. Results and observations from both serial sensing and individual recording indicate that serial sensing method using PZT is an efficient and quick method that has tremendous promising applications in SHM.

Keywords

Electromechanical Impedance (EMI), Serial Sensing, Piezoelectric effect, Root Mean Square Deviation (RMSD), Damage detection

 

4.

Study of stencil printing parameters for ball grid array formation at smaller pitch

Authors

Shrikant G. Kulkarni, Varsha A. Chaware, Girish J. Phatak

Affiliation

Centre for Materials for Electronics Technology (C-MET), Off Pashan road, Panchawati, Pune

Appears in

J. ISSS Vol. 4 No. 1, pp. 76-83, Mar - Sept. 2015.

Abstract

In the new packaging paradigm, the area array interconnections realized through Ball Grid Array have become a necessity. For being the most simple and production oriented process, the stencil printing method is being re-investigated for the formation of Ball Grid Array (BGA). This process is known to pose difficulties in forming BGA at small pitches. We have investigated the stencil printing process. This paper investigates the stencil printing process with the aim of forming uniform BGA at a pitch of 2 x (pad size). For present study, the target was to obtain hemispherical BGA on 0.76 x 0.76 mm square pads. The printing parameters viz. squeegee pressure, squeegee speed, snap off and aspect ratio have been studied over wide range of values by selecting two relatively thin (0.2 mm) and thick (0.4 mm) stencils. A maximum print volume of 0.26 mm3 was obtained using a 1.0 mm aperture for 0.4 mm stencil, at zero snap off, low squeegee speed and high squeegee pressure. It is noticed that these results can be generalized for the BGA preparation of any size barring the issue of stencil stiffness. BGA were prepared at the optimized stencil printing conditions on LTCC substrates  having 0.76 x 0.76 mm Ag/Pd pads using 90Pb/10Sn Type-IV solder paste. The optimized printing condition produced an average print volume of 0.256 mm3 and uniform hemispherical BGA with bump height of 0.37 ± 0.01 mm after reflow.

Keywords

Ball Grid Array (BGA), Stencil printing, Solder paste, Shear rate, Dwell time

 

5.

Transduction of A0 Lamb mode using rotationally misaligned air-coupled probes in composite laminates

Authors

C. Ramadas, Irfan Khan, Avinash S. Hood, Makarand Joshi

Affiliation

Composites Research Center, R&DE(E), DRDO, Pune, India

Appears in

J. ISSS Vol. 4 No. 1, pp. 76-83, Mar - Sept. 2015.

Abstract

Air-coupled transducers are used for transmission and reception of Lamb waves in composite materials. In order to transmit and  receive a Lamb wave with high amplitude, the transducers have to satisfy ‘coplanarity’ condition. Any misalignment between the transducers results in reduction in the amplitude. In the present work, a misalignment termed ‘rotational misalignment’ was introduced in one of the transducers (transmitter or receiver). Because of this misalignment, variation in amplitude with respect to the angle of misalignment of the fundamental anti-symmetric Lamb mode (Ao) in unidirectional and cross-ply composite laminates follows Gaussian curve. Furthermore, reduction in the amplitude of the Ao mode at 40° misalignment angle was 10–15% of the reference value.

Keywords

Ao Lamb mode, Air-coupled transducers, Composites,, Gaussian curve

 

6.

Complete development of a single cell PMUT transducer: design, fabrication, characterization, and integration

Authors

Ajay Dangia, Amod Hulgeb, Anish Somasundaranc, Rominus S. Valsalamc, Rudra Pratapa,b

Affiliation

aDepartment of Mechanical Engineering, IISc Bangalore, India

bCenter for Nano Science and Engineering, IISc Bangalore, India

cCenter for Development of Advanced Computing (C-DAC), Trivendrum, India

Appears in

J. ISSS Vol. 4 No. 1, pp. 61-69, Mar - Sept. 2015.

Abstract

Microfabricated ultrasonic sensors have opened new avenues for sensor applications from emerging consumer electronics to conventional medical imaging. This work reports design, fabrication, and electronic integration of a Piezoelectric Micromachined Ultrasonic Transducer (PMUT). PMUT cells have been fabricated by suspending a multilayer structure on silicon substrate consisting mainly of a passive base layer and an electronically excitable piezoelectric layer. In the reported design, the PMUT uses 1 μm-thick PZT as piezoelectric layer with top and bottom electrodes on 300 nm-thick SiO2 released after etching silicon handle layer of about 525 μm thickness. Fabricated PMUT devices have been characterized using Laser Doppler Vibrometry (LDV) in transmitter and receiver modes. Further, the PMUT has also been integrated with electronics and a single 1 mm diameter PMUT has been shown to work as a proximity sensor up to 10 cm distance.

Keywords

Ultrasonic, Piezoelectric, PMUT, MEMS

 

7.

The behaviour of continuous flow xenon difluoride etching of silicon

Authors

D. Drysdalea,b, A. O’Harab, C. H. Wanga

Affiliation

aInstitute in Signals, Sensors and Systems, Heriot-Watt University, Edinburgh, Scotland, UK

bMemsstar, Scottish Microelectronics Centre, Edinburgh, Scotland, UK

Appears in

J. ISSS Vol. 4 No. 1, pp. 70-75, Mar - Sept. 2015.

Abstract

The characterisation of silicon etching by xenon difluoride is discussed along with the presentation of process behaviours of etch parameters. Selectivity towards key semiconductor and MEMS materials are also discussed. We discuss a continuous flow process whereby xenon difluoride flows throughout the etch process. Unlike pulse processing regimes, which show slower overall etch rates and can be physically limited in process capabilities, the continuous process shows high etch rates on blanket and test designs, which highlight undercut etching rates. Undercut etch rates of up to 18 microns per minute are reported.

Keywords

XeF2, Silicon, Polysilicon, Etching, Selectivity, MEMS

 

 

8.

Wind vibration energy harvesting through macro fiber composites: a probabilistic approach

Authors

Abhishek Ghiyaa, A. Arockirajanb, Sayan Guptab

Affiliation

aResearch and Development Establishment, DRDO, Pune, India

bDepartment of Applied Mechanics, IIT Madras, Chennai, India

Appears in

J. ISSS Vol. 4 No. 1, pp. 76-83, Mar - Sept. 2015.

Abstract

Piezoelectric materials such as Macro Fiber Composites (MFC) have certain advantages such as flexibility and high endurance strength over bulk piezoelectric materials. An experiment and simulation based study is presented here for a P2 type (d31 effect) MFC patch for wind energy harvesting. A single cantilever beam configuration has been tested under harmonic and random (wind vibrations) excitations. Wind vibration test was done inside a wind tunnel for Beaufort scale level 5, which is the most common environmental condition. An average power density of 33.2 μW/cm3 and 1.32 μW/cm3 has been obtained from harmonic and wind vibration, respectively. A reliable and accurate Finite Element (FE) model has been created for simulating the output voltage. Probabilistic approach has been used to analyse and predict the output voltage data from the wind vibration experiment.

Keywords

MFC, PZT, Finite element, Wind vibration, Probabilistic approach

 

  Volume 3 Number 2 September 2014

1.

MEMS based Integrated Gas Sensor for NO2 and NH3

Authors

Rahul Prajesha,b, Nishit Jaina, V K Khannaa,b, V Guptac, Ajay Agarwala

Affiliation

aCSIR-Central Electronics Engineering Research Institute, Pilani 333031

bAcademy of Scientific and Innovative Research, New Delhi, India

cUniversity of Delhi, Delhi, India

Appears in

J. ISSS Vol. 3 No. 2, pp. 1-6, Sept. 2014.

Abstract

Numerous toxic and hazardous gases are used in various industrial applications. An exposure to these gases even in trace level can be lethal or it may lead to various chronic respiratory problems including shortness of breath, coughing and fluid in the lungs. Hence, detection of these gases is of utmost significance. This paper presents the design, fabrication and the characterization of a gas sensor using MEMS technologies. The device design is supported by Joule heating simulations. A Platinum micro-heater is integrated in the metal oxide based gas sensors, to achieve an operating temperature up to 3430C. A Sensor temperature of 2500C is achieved at 68mW, and 3000C at 86mW power. SnO2 (sputtered) thin film is used as the sensing film and has been characterized for two gases, namely NO2 and NH3. Platinum is also used for making Inter Digitated Electrodes (IDE) with a spacing of ~30μm. A very significant response of approximately 159 (ΔR/R) at 1500C for NO2, and 5.44 (ΔR/R) at 2500C for NH3 was observed.

Keywords

Gas Sensor, Pt-Micro-heater, Inter Digitated Electrodes (IDE), SnO2, NO2

 

 

2.

Fabrication of Compliant Micro Grippers Using SU-8 with a Single Mask  

Authors

Santosh D. B. Bhargav, Nikhil Jorapur, G. K. Ananthasuresh

Affiliation

Department of Mechanical Engineering, Indian Institute of Science, Bangalore, India.

Appears in

J. ISSS Vol. 3 No. 2, pp. 7-13, Sept. 2014.

Abstract

In this paper, we present a single-mask process for fabricating compliant micro-grippers using SU-8. The fabricated compliant grippers fit within a footprint of about 10 mm x 10 mm, and have the smallest feature size of about 5 μm. A novel aspect of the process is in using a positive photoresist, AZ-4562, as a sacrificial layer to release the gripper and make it movable. It is demonstrated that the use of AZ-4562, compared with the conventional methods; reduces the number of steps required to fabricate the grippers and similar devices. Another novel feature is offsetting the position of the substrate on a spin-coater, which makes it possible to coat the sample with the sacrificial layer for a specific region of the substrate. The effectiveness of the fabrication process is demonstrated by fabricating the grippers, and testing them to handle single biological cells. It is shown that, by using the developed process, one can obtain a sacrificial layer of 6.13±0.1 μm and an SU-8 gripper with a thickness of 44±1 μm with a good repeatability. The details of the various steps involved in the fabrication and the parameters used in these steps are described. The proposed process is amenable for batch-production.

Keywords

SU-8 micro-gripper, compliant mechanism, AZ-4562, Photolithography

 

 

3.

Dynamic Response of Multiphase Magneto-Electro-Elastic Composites Subjected to Time-Harmonic Electric Excitation

Authors

B. Biju and K.Shankar

Affiliation

1Department of Mechanical Engineering,  M.A.College of Engineering, Kerala, 686 666, India.

2Professor, Machine Design Section,  Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600 036, India.

Appears in

J. ISSS Vol. 3 No. 2, pp. 14-20, Sept. 2014.

Abstract

Dynamic loading will generate time varying electric and magnetic fields in the magneto-electro-elastic (MEE) continuum. The magneto-mechanical response of the two phase MEE beam is investigated; when the structure excited by the time-harmonic electric potential at different locations on the structure. Studies are carried out for clamped-free mechanical boundary condition of the beam; with a potential difference applied between the two ends as well as the top and bottom of the beam. It is seen that both the mechanical fields and the components of the magnetic potential in the longitudinal x-direction and transverse z-direction are excited by the top and bottom electric excitation of the beam; whereas the magneto-mechanical fields are seldom excited by the end loading.

Keywords

Magneto-electro-elastic, magnetic vector potential, electric loading, finite element.

 

 

4.

Preparation of a Silicon oil based Magneto Rheological Fluid and an Experimental Study of its Rheological Properties using a Plate and Cone Type Rheometer

Authors

Shreedhar Kolekar1, Rajashekar V. Kurahatti2, Prashanth P.K1, Vikram Kamble1, Nitin Reddy1

Affiliation

1Mechanical Engineering Department, St. Joseph Engineering College, Mangalore - 575028.

2Mechanical Engineering Department Basaveshwar Engineering College, Bagalkot - 587102

Appears in

J. ISSS Vol. 3 No. 2, pp. 21-25, Sept. 2014.

Abstract

Magnetorheological (MR) fluids are suspensions of micron-sized magnetisable particles disperse in a nonmagnetic carrier fluid. The essential characteristic of these materials is that they can be rapidly and reversibly varied from the state of a Newtonian-like fluid to that of a stiff semisolid with the application of a moderate magnetic field. In this research work a silicon based magnetorheological fluid is prepared in the laboratory and tested using a cone and plate type rheometer for finding its characteristics of a MR fluid by measuring different rheological properties such as viscosity, shear stress, yield stress etc for different samples in detail. The properties of MR Fluids in terms of storage modulus (G'), loss modulus (G'') and loss factor (G''/G') are also presented.

Keywords

Magnetorheological fluid, Shear stress, Shear rate, Shear viscosity, Phase angle.

 

 

5.

Analytical and Numerical Modeling of the Effect of Variable Flow Boundaries on the Squeeze Film Behavior in MEMS

Authors

A. Roychowdhury1,2, S. Patra3, A. Nandy1, R. Pratap1,2

Affiliation

1Dept. of Mechanical Engineering, Indian Institute of Science Bangalore,

2Center for Nano Science and Engineering, Indian Institute of Science Bangalore,

3Dept. of Mechanical Engineering, Jadavpur University Kolkata,

Appears in

J. ISSS Vol. 3 No. 2, pp. 26-38, Sept. 2014.

Abstract

We analyze the forces produced by a thin fluid film (called squeeze film) present between an oscillating elastic rectangular microplate and a fixed substrate under different practical flow boundary conditions. The plate is fixed along its edges and is assumed to vibrate in its first fundamental mode. The fluid underneath is squeezed differently depending on the side venting condition. We derive analytical expressions for the squeeze film damping and spring forces for different flow boundary conditions – all sides open (OOOO), all sides closed (CCCC), adjacent sides open (OOCC), etc. The derivation is illustrated considering the all sides open case results. We then discuss the results for different flow boundary conditions. We find that restricting the fluid flow along the three edges compared to the all sides open case results in as much as 45 times increase in the squeeze film induced stiffness and six times increase in the peak damping. These results indicate the use of boundary venting conditions as an additional design parameter for controlling damping and ; hence, Q as well as the squeeze film stiffness. We verify our analytical results with a FORTRAN simulation data based on a finite element methodology. The numerical results show a good agreement with the analytical solutions.

Keywords

 Squeeze film, Flow boundaries, Elastic micro-plate, FEM coupled.

 

 

6.

A Technology Overview and Applications of Bio-MEMS

Authors

Nidhi Maheshwari, Gaurav Chatterjee, V. Ramgopal Rao

Affiliation

Department of Electrical Engineering, Indian Institute of Technology Bombay, Mumbai, India-400076.

Appears in

J. ISSS Vol. 3 No. 2, pp. 39-59, Sept. 2014.

Abstract

Miniaturization of conventional technologies has long been understood to have many benefits, like: lower cost of production, lower form factor leading to portable applications, and lower power consumption. Micro/Nano fabrication has seen tremendous research and commercial activity in the past few decades buoyed by the silicon revolution. As an offset of the same fabrication platform, the Micro-electro-mechanicalsystems (MEMS) technology was conceived to fabricate complex mechanical structures on a micro level. MEMS technology has generated considerable research interest recently, and has even led to some commercially successful applications. Almost every smart phone is now equipped with a MEMS accelerometer-gyroscope system. MEMS technology is now being used for realizing devices having biomedical applications. Such devices can be placed under a subset of MEMS called the Bio-MEMS (Biological MEMS). In this paper, a brief introduction to the Bio-MEMS technology and the current state of art applications is discussed.

Keywords

Bio-MEMS, immobilization, cantilever, micro-fabrication, biosensor.

   
  Volume 3 Number 1 March 2014

1.

Molecular Dynamics Simulation of Residual Stress in aSi Quantum Dot Embedded in SiO2

Authors

Bhamy Maithry Shenoya , Gopalkrishna M. Hegdeb and D. Roy Mahapatraa

Affiliation

aDepartment of Aerospace Engineering, Institute of Science, Bangalore 560012, India

bCentre for Nano Science and Engineering, Indian Institute of Science, Bangalore 560012, India

Corresponding author: [email protected]

Appears in

J. ISSS Vol. 3 No. 1, pp. 1-7, March 2014.

Abstract

Deformation plays a fundamental role in determining the properties of nano scale systems, for example in electronic energy band structures. A method to compute the residual stress distribution in nanocrystalline silicon (nc-Si) quantum dots embedded in an amorphous silicon dioxide (a-SiO2) matrix using molecular dynamic simulations has been developed. In order to understand the process of formation and stabilization of quantum dots, we consider two different processes of cooling. In one case, a quenching condition is applied, and, in another case, a slow annealing condition is applied. Atomic level stresses are calculated using the virial theory. It is observed from the simulation results that cooling rates significantly affect the residual stress distribution. Quenching produces a high density of defects in the crystalline core as well as in the diffused interface region, whereas annealing reduces the density of defects and gives a very well defined interface region between the crystalline Si core and amorphous SiO2 shell. Further, annealing produces compressive stress close to the interface region similar to the experimental observations reported earlier. Altering the defect distribution is a potential approach to designing optimal energy band structures.

Keywords

 Si, SiO2, quantum dot, molecular dynamics simulation, residual stress, annealing, quenching, virial stress.

 

 

2.

A Note on Modelling Directionality in Piezoresistivity

Authors

Sreenath Balakrishnan, Kaustubh Deshpande, and G.K. Ananthasuresh

Affiliation

Computational Nanoengineering (CoNe) Group and Mechanical Engineering, Indian Institute of Science, Bangalore 560012

Corresponding author: [email protected]

Appears in

 J. ISSS Vol. 3 No. 1, pp.18-27, March 2014.

Abstract

When computing the change in the electrical resistivity of a piezoresistive cubic material embedded in a deforming structure, the piezoresistive and the stress tensors should be in the same coordinate system. While the stress tensor is usually calculated in a coordinate system aligned with the principal axes of a regular structure, the specified piezoresistive coefficients may not be in that coordinate system. For instance, piezoresistive coefficients are usually given in an orthogonal Cartesian coordinate system aligned with the <100> crystallographic directions but designers sometimes deliberately orient a crystallographic direction other than <100> along the principal directions of the structure to increase the gauge factor. In such structures, it is advantageous to calculate the piezoresistivity tensor in the coordinate system along which the stress tensors are known rather than the other way around. This is because the transformation of stress will have to be done at every point in the structure but the piezoresistivity tensor needs to be transformed only once. Here, by using tensor transformation relations, we show how to calculate the piezoresistive tensor along any arbitrary Cartesian coordinate system from the piezoresistive coefficients for the <100> coordinate system. Some of the software packages that simulate the piezoresistive effect do not have interfaces for the calculation of the entire piezoresistive tensor for arbitrary directions. This warrants additional work for the user because not considering the complete piezoresisitive tensor can lead to large errors. This is illustrated with an example where the error is as high as 33%. Additionally, for elastic analysis, we used a hybrid finite element formulation that estimates stresses more accurately than the usual displacement-based formulation. Therefore, as shown in an example where the change in resistance can be calculated analytically, the percentage error of our piezoresistive program is an order of magnitude lower relative to the displacement-based finite element method.

Keywords

Piezoresistivity, coordinate transformation, fourth order tensor, hybrid finite elements

 

 

3.

Low Frequency Vibration Energy Harvesting using Arrays of PVDF Piezoelectric Bimorphs

Authors

Rammohan S.a, Ramya C. M.c, Jayanth Kumar S.b, Anjana Jainb, Rudra Pratapa,c

Affiliation

aDepartment of Mechanical Engineering, Indian Institute of Science, Bangalore 560012

bNational Aerospace Laboratories, Bangalore 560017

cCentre for Nano Science and Engineering, Indian Institute of Science, Bangalore 560012

Corresponding author: [email protected]

Appears in

J. ISSS Vol. 3 No. 1, pp.18-27, March 2014.

Abstract

Power harvesters based on the piezoelectric effect are more promising in harnessing energy from ambient vibrations. In this paper, piezoelectric bimorph resonators in the form of Polyvinylidinefluoride (PVDF) cantilevers are studied and used in an array with optimal terminal combination for maximizing the power generated from low frequency vibrations. The thickness of the passive sandwich layer and the poling direction in each film are observed to be crucial in determining the total power generated from the PVDF bimorph. Experimentally, bimorph cantilevers made of 55mm thick PVDF film and sized to resonate between 30 to 40 Hz are used in similarly poled as well as oppositely poled configurations and their output measured as voltage across a 1 MW load resistance. The similarly poled bimorph outperforms the oppositely poled configuration by more than doubling the output voltage. Further enhancement in the output is observed by introducing a sandwich layer of 50 μm thick copper foil between the two similarly poled PVDF layers. Experiments with three such devices connected in parallel in an array and resonating at 33 Hz with an input acceleration of 0.8 g results in 2.8 μW power generation. This result shows the promise of PVDF as a candidate material for energy harvesting resonators despite its low electromechanical coupling coefficient (ke). Low cost and ease of production may be especially attractive for PVDF.

Keywords

Energy harvesting, piezoelectric converter, array of bimorphs, electromechanical coupling coefficient, PVDF.

 

 

4.

Nanotextile Bio-sensors for Mobile Wireless Wearable Health Monitoring of Neurological and Cardiovascular Disorders

Authors

Pratyush Rai1, Sechang Oh1, Prashanth Shyamkumar1, Mouli Ramasamy1, Robert E. Harbaugh4 and Vijay K. Varadan1,2,3,4

Affiliation

1Department of Electrical Engineering, University of Arkansas, Fayetteville, AR 72701

2Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR 72701

3Global Institute of Nanotechnology, 700 Research Center Blvd, Fayetteville, AR 72701

4Department of Neurosurgery, Pennsylvania State University, Hershey, PA 17033

Corresponding author: [email protected]

Appears in

J. ISSS Vol. 3 No. 1, pp. 28-77, Mar. 2014.

Abstract

Health and long term care is a growth area for wearable heath monitoring systems. Wearable diagnostic and therapeutic systems can contribute to timely point-of-care for patients with chronic health conditions, especially chronic neurological disorders, cardiovascular diseases and strokes that are leading causes of mortality worldwide. Diagnostics and therapeutics for patients under timely pointof-care can save thousands of lives. However, lack of access to minimally-intrusive monitoring systems makes timely diagnosis difficult and sometimes impossible. Existing ambulatory recording equipment are incapable of performing continuous remote patient monitoring because of the inability of conventional silver-silverchloride- gel-electrodes to perform long-term monitoring, non-reusability, lack of scalable-standardized wireless communication platforms, and user-friendly design. Recent progress in nanotextile biosensors and mobile platforms has resulted in novel wearable health monitoring systems for neurological and cardiovascular disorders. This chapter discusses nanostructured-textile-based dry electrodes that are better suited for long-term measurement of electrocardiography (ECG), electroencephalography (EEG), electrooculography (EOG), electromyography (EMG) and bioimpedance with very low baseline noise, improved sensitivity and seamless integration into garments of daily use. It discusses the bioelectromagnetic principles of the origin and propagation of bioelectric signals and nanosensor functioning, which provide a unique perspective on the development of novel wearable systems that harness their potential. Combined with state-of-the-art embedded wireless network devices to communicate with smartphones, laptops or directly to remote servers through a mobile network (GSM,4G-LTE,GPRS), they can function as wearable wireless health- diagnostic systems that are more intuitive to use.

Keywords

Textile nanosensor, smart textile, wireless, bioelectromagnetism, ECG, EEG, EOG, EMG, cardiovascular disorder, neurological disorder
   
  Volume 2 Number 2 September 2013

1.

Ni30Ti50Pt20 High Temperature Shape Memory Alloy (HTSMA) Wires: Processing Related Issues

Authors

K.V. Ramaiah, C.N. Saikrishna, M. Sujata and S.K. Bhaumik

Affiliation

Council of Scientific and Industrial Research (CSIR),  National Aerospace Laboratories, Materials Science

Division, Bangalore 560 017, INDIA 

Corresponding author email: [email protected]

Appears in

J. ISSS Vol. 2 No. 2, pp. 1-9, Sept. 2013.

Abstract

There is a growing demand for high temperature shape memory alloys (HTSMAs) for applications in areas such as aeroengines, chemical industries, and nuclear power plants, where the ambient temperature is relatively high (150-350°C). Platinum addition to binary NiTi, with Pt substituting for Ni, has been found to raise the transformation temperatures of the alloy with the advantage of retaining the transformation hysteresis in the range 25-35°C. In the present study, a NiTiPt alloy was selected for processing into the wire form for applications in the range 200-250°C. Addition of Pt of about 20 at.% to binary NiTi was required to raise the transformation temperatures of the alloy above 200°C. It was found that Pt addition significantly changed the processing characteristics of the NiTiPt alloy from those of binary NiTi alloys. For successful processing of the NiTiPt wires, it was necessary to modify the process usually followed for binary NiTi alloys. Also, additional steps were incorporated to overcome the problems inherent to this alloy system. Some of these aspects related to processing of this alloy in wire form are discussed in this paper.

Keywords

High temperature shape memory alloy, NiTiPt, melting, secondary processing, wire properties

 

 

2.

The Buckling of Metal Thin Films on Soft Elastomers: Use in Flexible Electronics

Authors

Debashis Maji1a, Puneet Manochaa,b, and Soumen Dasa

Affiliation

aSchool of Medical Science & Technology, Indian Institute of Technology, Kharagpur, WB-721302, India;

bDepartment of Instrumentation and Control, Graphic Era University, Dehradun, UK-248001, India

1Corresponding Author email: [email protected]

Appears in

J. ISSS Vol. 2 No. 2, pp. 10-17, Sept. 2013.

Abstract

The deposition of a metal thin film over soft elastomers like PDMS is associated with the distribution of random buckles over its surface. The effective utilization of these sinusoidal buckles in the bending mode of the entire composite structure finds lot of applications as a flexible MEMS sensor. The present article deals with the effective control of these buckles in the successful realization of flexible sensors. The deposition of a nichrome thin film over a non-planar elastomeric surface induces highly ordered buckle structures over the elastomeric ridge. These buckles, aligned parallel to the ridge width, can be used in effective bending of the sensor along its length without resulting in any cracking of the thin film. The fabrication of a non-planar PDMS surface using the soft lithography technique, the deposition of a crack-free nichrome film, and the generation of highly ordered buckles over the non-planar geometry have been discussed in the present paper. The deposition time has also been varied to optimize the buckle wavelength needed for effective bending and the results have been compared with the theoretical values.

Keywords

PDMS, flexible sensors, buckles, nichrome thin film, non-planar topology

 

 

3.

A Comparison of Burst Strength and Linearity of Pressure Sensors having Thin Diaphragms of Different Shapes

Authors

Vidhya Balaji and K.N. Bhat

Affiliation

Centre for Nano Science and Engineering, Indian Institute of Science, Bangalore-560012

Corresponding author email:[email protected]

Appears in

J. ISSS Vol. 2 No. 2, pp. 18-26, Sept. 2013.

Abstract

The shapes of diaphragms most commonly used for Micro Electro Mechanical Systems (MEMS) applications are square, circular and rectangular. The aim of this analysis is to highlight the distinctions among these three shapes with respect to burst strength and linearity and to identify the shape with the best characteristics for a given diaphragm thickness and width. A Finite Element (FE) Analysis carried out with Coventorware software is used to simulate the stress distribution for a range of applied pressure on the diaphragm. We consider single-crystal silicon <100> as the diaphragm material. Anisotropic wet etch is the means of fabrication for the rectangular and square diaphragms and for the circular diaphragm it is dry etching. We show that the circular diaphragm gives us both good linearity characteristics and the highest burst stress tolerance characteristics.

Keywords

Burst strength, Linearity, Pressure sensor, Stress Distribution, Diaphragm

 

 

4.

Radio Frequency Micro Electro Mechanical Systems-An Overview

Authors

Shiban K. Koul and Sukomal Dey

Affiliation

Centre for Applied Research in Electronics, Indian Institute of Technology, Delhi, New Delhi 110016

Corresponding Author Email: [email protected]

Appears in

J. ISSS Vol. 2 No. 2, pp. 27-75, Sept. 2013.

Abstract

This paper reviews the design and development of different building blocks of RF MEMS sub-systems. The blocks include switches, tunable capacitors, integrated inductors, filters, reconfigurable circuits, phase shifters and antennas. Starting with the details of a general micromachining process, a behavioral analysis of RF MEMS components and design challenges with present state-of-the-art are discussed. Different fabrication processes are outlined and discussed. The functional behaviors of different RFMEMS components are experimentally investigated over certain frequency bands of interest and validated through system level simulation. Finally, a low cost packaging scheme has been presented.

Keywords

RF MEMS, Metal contact switch, coplanar waveguide, switched line phase shifter, DMTL phase shifter, inductor, varactor, filter, micromachined antenna, RF MEMS packaging, reconfigurable circuits

   
 

Volume 2 Number 1 March 2013

1.

Design and Development of a PDMS Membrane based SU-8 Micropump for Drug Delivery System

Authors

Bidhan Pramanick1a, P. K. Deyb, Soumen Dasc, T. K. Bhattacharyyad

Affiliation

a Department of Avionics, IIST Valiamala, Department of Space, Trivandrum, India-695547

b Advanced Technology Development Centre, IIT Kharagpur, Kharagpur, India-721302

c School of Medical Science and Technology, IIT Kharagpur, Kharagpur, India-721302

d Department of E & ECE, IIT Kharagpur, Kharagpur, India-721302

1[email protected]

Appears in

J. ISSS Vol. 2 No. 1, pp. 1-9, Mar. 2013.

Abstract

A micropump is one of the key components of a Drug Delivery System (DDS) and it can be integrated with microneedle for localized drug delivery in even one single cell. The conventional drug delivery system is replaced by MEMS (Micro-electro-mechanical system) DDS due to its ability to deliver very small amounts of the drug in the dermis region of the patient’s body without any pain. This paper presents the design and fabrication of a PDMS (Polydimethylsiloxane) membrane based SU-8 micropump. The pump chamber is made of SU-8 on a glass substrate. A separately processed PDMS layer of 150 μm is treated in oxygen plasma to make a strong bond with SU-8. The detailed fabrication procedure is described here and the advantage of using a PDMS membrane as well as SU-8 material is also discussed. Piezoelectric discs are used for the actuation of the micropump membrane. The deflections of the membrane at different frequencies are measured using MSA 400 (Micro System Analyzer) of Polytec and they are shown to be maximum at 5009 Hz frequency for 30 V. The flowrate measurement using

DI water is also discussed here.

Keywords

Drug Delivery System, PDMS, SU-8, Microfabrication, Micropump, Piezoelectric

 

 

2.

Digital Microfluidics and its Integration with a Fluidic Microreactor

Authors

Paresh Kumar and Enakshi Bhattacharya1

Affiliation

Microelectronics and MEMS Laboratory,

Department of Electrical Engineering,

IIT Madras, Chennai-600036, India

1[email protected]

Appears in

J. ISSS Vol. 2 No. 1, pp. 10-19, Mar. 2013.

Abstract

We present the steps to fabricate a Digital Microfluidics (DMF) platform for handling fluidic sample delivery. This is followed by the integration of the DMF chip with a microreactor that is an Electrolyte Insulator Semiconductor Capacitor (EISCAP) biosensor. DMF is used for handling basic fluidic operations like droplet transportation, and splitting and dispensing smaller droplets from a reservoir. All the droplet operations on DI water droplets mentioned above are possible with AC actuation at ~35 Vrms but this result in electrolysis on the transportation of an electrolyte droplet. DC actuation is used to solve the problem of electrolysis and to transport the electrolyte droplets. Interdigitated electrode geometry improves the device performance. The DMF substrate is used to deliver fluidic samples via a through hole in the DMF wafer to a bulk micromachined EISCAP biosensor bonded to the DMF wafer. The dimension of the through hole and the extent of its coverage with the control electrode are optimized for the successful delivery of the fluidic samples to the bonded biosensor below. The devices are tested by delivering droplets of electrolyte to the bonded reactor below. Capacitance-Voltage (C-V) measurement done on the integrated device confirms the successful delivery of the electrolyte to the microreactor. This integration technique can manipulate fluid handling work on the DMF substrate without compromising the functionality of the fluidic reactor.

Keywords

Digital Microfluidics (DMF), Bulk Micromachining, Integration

 

 

3.

Turning Lamb mode based crack growth prediction for GIC determination in laminated composites

Authors

C. Ramadas1a, Avinash Hooda, Anoop Ananda, Krishnan Balasubramaniamb and Makarand Joshia

Affiliation

aComposites Research Centre, R&DE(E), DRDO, Alandi

Road, Pune, India-411 015

bCentre for Non-destructive Evaluation, Indian Institute of

Technology Madras, Chennai, India-600 036

1[email protected]

Appears in

J. ISSS Vol. 2 No. 1, pp. 20-26, Mar. 2013.

Abstract

A turning Lamb mode propagates from one sub-laminate to the other at a delaminated region. In the present work, an attempt has been made to explore the use of the fundamental symmetric and antisymmetric Turning Lamb modes for the prediction of crack growth for the determination of the strain energy release rate (GIC) in a laminated composite specimen. Expressions based on Time-of-Flight were derived to estimate the crack growth. The proposed methodology has been validated through numerical simulations.

Keywords

Turning Lamb modes, Crack growth, Strain Energy Release Rate (GIC)

 

 

4.

Fringe Field Junctionless FET as a Sensitive Displacement Sensor

Authors

Thejas1, Navakanta Bhat, Rudra Pratap and K N Bhat

Affiliation

Centre for Nano Science and Engineering,

Indian Institute of Science,

Bangalore-560012

1[email protected]

Appears in

J. ISSS Vol. 2 No. 1, pp. 27-38, Mar. 2013.

Abstract

This paper reports a novel transduction proposition with merits of good sensitivity using a Junctionless FET to pick-up inertial changes in MEMS or NEMS devices. Here the NEMs gate is displaced in an out-of-plane direction when subjected to any external vibrations. The displacement is assumed to be a forced plate motion. The resulting change in the gate fringe field due to this displacement modulates the drain current of the Junctionless Field Effect Transistor (JLFET). The displacement induced fringe field change (relative to the FET channel and the Ground planes) brings out a distinct shift in the IDS-VGS characteristics of the JLFET. When the gate displacement is in a few nano-meters (less than 5nm) range, the fringe field effect is dominant and the gate voltage required to deplete the channel to force an eventual turn-off tends to decrease. For 2nm displacement, the JLFET with a channel doping of ND = 8X1018 cm-3 operating at a bias point of VGS = - 47.7V, we observe 2-orders of magnitude change in IDS (nearly 98% change). We show that the equivalent change in capacitance measured in this technique is in a few zepto farads. TCAD 3D simulations are presented to validate the sensitivity of the Fringe Field JLFET (FF-JLFET).

Keywords

Fringe Field,  Junctionless FET, Inertial Sensing,  Zepto farad

 

 

5.

MEMS Pressure Sensors- An Overview of Challenges in Technology and Packaging

Authors

K. N. Bhat1 and M. M. Nayak

Affiliation

Centre for Nano Science and Engineering,

Indian Institute of Science,

Bangalore-560012

1[email protected]

Appears in

J. ISSS Vol. 2 No. 1, pp. 39-71, Mar. 2013.

Abstract

Pressure sensors are required in all walks of life, irrespective of civilian, defense, aerospace, biomedical, automobile, Oceanography or domestic applications. Naturally, rapid progress has been made in micromachined pressure sensors and the microsystems using these sensors. Starting with metal strain gauges and moving forward with silicon based pressure sensors with flat diaphragms, the search for devices which can operate in harsh environments involving corrosive fluids and high temperatures has spurred activities which lead to pressure sensors using harder materials such as Silicon Carbide (SiC) and Carbon Nano Tubes (CNT). The present article provides an overview of these pressure sensors including their design, engineering, technology and packaging challenges.

Keywords

Pressure sensors (Low pressure, High pressure), Microsystems, MEMS, Silicon Carbide, Piezo resistors (Si, PolySi, SiC, CNT), MOS integrated pressure sensors, Microsystem packaging technology.

   
  Volume 1, Number 1, September 2012

1

Stiction Free Fabrication of MEMS Devices with Shallow Cavities Using a Two-Wafer Anodic Bonding Process

Authors

K. Jayaprakash Reddya*, K.N. Bhatb and Rudra Pratapa,b

Affiliation

aDepartment of Mechanical Engineering,

bCenter for Nano Science and Engineering

Indian Institute of Science, Bangalore-560012, India

* [email protected]

Appears in

J. ISSS Vol. 1 No. 1, pp. 1-9, Sept 2012.

Abstract

MEMS devices often employ free standing structures, such as beams and plates, over a cavity that allows space for structures to bend or oscillate, and also acts as a dielectric medium for the electrostatic field between the structure and the electrode placed at the bottom of the cavity. Such cavities are common in inertial and acoustic sensors. In order to create these cavities, a sacrificial etch is used in traditional fabrication methods such as surface micromachining. The sacrificial etch and release is a tricky process that often leaves structures only partially released. In addition, if the free structure is a large plate or membrane as in the case of MEMS gyroscopes, the sacrificial release requires many etch holes that may not be desirable in the structure. Here, we describe a two-wafer process in which the sacrificial release step for creating cavities, and hence the problem of stiction, can be avoided altogether. This process involves anodic bonding of the two wafers that is easily optimized for the desired result. We discuss the process first on a test structure and then show how we successfully use this process to fabricate a two-mass vibratory gyroscope.

Keywords

Wafer bonding, Anodic bond, Gyroscope, Capacitive Micro machined Ultrasound Transducer (CMUT), Microphone, SAM (Scanning Acoustic Microscopy).

 

 

2.

Low loss 2-port OADM using 1-D Photonic Crystal and 3-Port Optical Circulator

Authors

Renilkumar M,1,* and Prita Nair1

Affiliation

1Dept. of Physics, SSN College of Engineering, Chennai,

Tamilnadu, India, 603110

* [email protected]

Appears in

J. ISSS Vol. 1 No. 1, pp. 10-15, Sept 2012.

Abstract

The simple architecture of a 2-port optical add drop multiplexer (OADM) using a 1-D photonic crystal (PC) filter and a 3-port optical circulator is presented. A low insertion loss of less than 2dB for express channels and 7dB for a drop channel is demonstrated using a superluminescent diode laser and an optical spectrum analyzer in the 1450nm-1650nm wavelength range. The channel isolation is 18dB. The main component of the OADM is the photonic crystal filter which is realized by a simple and low cost wet anisotropic etching of <110> oriented silicon. The pass band width of the drop channel at a peak wavelength of 1557nm is less than 7nm and a thermally induced wavelength drift of 0.04nm/K is experimentally measured. Therefore, this low cost solution is best suited for metro CWDM networks, where the channel spacing is 20nm.

Keywords

Optical add drop multiplexer, Photonic crystal filter, Wavelength division multiplexing

 

 

3.

Nanoscale Control of Electro-migration for Resistance Tuning of Metal Lines

Authors

Santanu Talukder1*, Arindam Ghosh2 and Rudra Pratap1

Affiliation

1Center for Nano Science and Engineering, and Department

of Mechanical Engineering,

2Department of Physics Indian Institute of Science, Bangalore-560012, India

[email protected]

Appears in

J. ISSS Vol. 1 No. 1, pp. 16-22, Sept 2012.

Abstract

Electromigration in metal films is a well known phenomenon in the microelectronics field and is usually regarded as a serious problem for interconnect reliability. Here, we exploit electromigration in a constructive way to devise a process for enhancing metal piezoresistivity. A recent study [Mohanasundaram et al., 2012] has shown that electromigration can be used for nanoscale manipulation of local morphology in thin metallic lines to drastically improve their piezoresistivity. This development has significant impact on strain gauge technology, especially for MEMS and NEMS devices. The key to this development, however, is a reliable control over the electromigration process. In this study, we have used electromigration to get a stable increased resistance for gold nano lines without breaking the line. We have used feedback controlled electromigration where the incremental resistance has been used as the main control parameter. Using this technique we have been able to increase the resistance of gold nanowires four fold. We present an algorithm for the closed loop control, use it successfully to increase the resistance of gold lines by four times, and show that this technique can be used to carry out rapid, stable and controlled electromigration. The intended application is significant enhancement of piezoresistive sensitivity of metal lines in MEMS and NEMS devices.

Keywords

Electromigration; Feedback control; Piezoresistivity; Strain gauge

 

 

4.

FxLMS Algorithm with Feedback Neutralization for Active Vibration Control

Authors

C.Karthikeyan1a and Shashikala Prakash 2a

Affiliation

aStructural Technologies Division, National Aerospace Laboratories,

PB 1779, Kodihalli, Bangalore, India 560017

1a[email protected]

Appears in

J. ISSS Vol. 1 No. 1, pp. 23-33, Sept 2012.

Abstract

The purpose of this paper is to present an adaptive control approach to vibration control using FxLMS algorithm with feedback Neutralization. Active Vibration control (AVC) uses secondary sources to cancel vibrations from primary sources based on the principle of super position. A feedforward FxLMS - AVC system applied to structure normally uses a reference sensor, a control unit, an actuator to generate secondary vibration and an error sensor to monitor the response of the structure. However, the control actuator which is used to cancel the primary vibrations will also generate vibrations in the structure. These secondary vibrations not only cancel the vibration, but also reach the reference sensor, resulting in a corrupted reference signal which is picked up by the reference sensor. The coupling of the vibrations from the control actuator to the reference sensor is called Structural Feedback. The presence of strong structural feedback degrades the performance of AVC systems, and, in the worst case, the AVC system may become unstable. This structural feedback problem is solved by introducing a feedback neutralization filter in the controller in parallel with the structural feedback path. The FxLMS with feedback neutralization has been implemented for a single channel active control system in MATLAB. The FxLMS with feedback neutralization guarantees the stability of AVC systems over conventional FxLMS – AVC systems.

Keywords

Active Vibration Control, Filtered X LMS algorithm, feedback neutralization, Principle of super position, Structural feedback.

 

 

5.

Feasibility Studies on MEMS Oxygen Flow Sensors by Differential Pressure Method for Pediatric Ventilators

Authors

M.Rajavelu1a, D.Sivakumara, R.Joseph Daniela, and K.Sumangalab

Affiliation

aNational MEMS Design Centre (NPMaSS),

Dept. of Electronics and Instrumentation Engineering,

bDepartment of Civil and Structural Engineering, Annamalai University,

Annamalainagar – 608 002, India.

1a[email protected]

Appears in

J. ISSS Vol. 1 No. 1, pp. 34-45, Sept 2012.

Abstract

This paper presents the outcome of the investigations on the measurement of oxygen flow by the differential pressure method in a pediatric ventilator system. The specialty of this flow measurement system is that it is realized using a meso channel integrated with two micro pressure sensors. The simulation results obtained from the COMSOL Multiphysics MEMS design tool show that the meso channel with a diameter of 500 μm and a length of 20 mm can cause a measurable pressure drop between the upstream and downstream without affecting the flow. Further investigations on thin film silicon diaphragms with embedded piezoresistors for sensing upstream and downstream pressures show that it is essential to employ thin diaphragms for pressure sensing in this application to achieve higher sensitivity with reasonably good linearity. However, very thin diaphragms result in more non linearity and are difficult to realize. Hence, the authors have tried to achieve this by employing thick diaphragms but with perforations. The IntelliSuite MEMS design tool has been used to create and analyze the pressure sensors with non-perforated and perforated silicon diaphragms. The results show that it is possible to achieve more than 90% improvement in deflection and sensor sensitivities and more than 135% improvement in stress generation with a 40% perforated area irrespective of the thickness of the diaphragm. This leads to the conclusion that the perforations realized on thicker diaphragms are suitable alternatives with a more satisfactory performance than very thin non-perforated diaphragms. This work further demonstrates that it is possible to design a flow measurement system by the differential pressure method using micro sensors integrated with a meso channel.

Keywords

Piezoresistive, ventilator system, pressure sensor, perforated diaphragm

 

 

6.

Implementation of an Active Vibration Control Technique on a Full Scale Space Vehicle Structure

Authors

Raja S1*, Janardhanam S1, Shankar V1, Balakrishnan B1, Rekha K R2 and Asraff A K2

Affiliation

1Structural Technologies Division,

CSIR-National Aerospace

Laboratories, Bangalore, India 560 017

2Liquid Propulsion Systems Centre (ISRO), Valiamala,

Thiruvananthapuram, India 695 547

*S. Raja, email: [email protected]

Appears in

J. ISSS Vol. 1 No. 1, pp. 46-54, Sept 2012.

Abstract

This paper addresses the implementation issues involved in an active vibration control (AVC) technique using piezoelectric stack actuators. It explains briefly the design and development of a broad band active vibration isolator (AVI) and subsequently presents the details of how these AVIs are employed in real time AVC application. The actuator electronics and the control scheme development have been highlighted. The AVC results are presented for four elastic modes in terms of Power Spectral Densities in open and closed loop configurations.

Keywords

Active Vibration Control (AVC), Active Vibration Isolator (AVI), Power Spectral Density (PSD)

 

 

7.

Design, Fabrication and Characterization of RF MEMS Varactor for VCO Application

Authors

Sukomal Dey1a and Shiban.K.Koula

Affiliation

aRF and Microwave Laboratory, Centre for Applied Research in Electronics (CARE)

Indian Institute of Technology, Delhi

1a[email protected]

Appears in

J. ISSS Vol. 1 No. 1, pp. 55-64,  Sept 2012.

Abstract

A tunable capacitor that employs micro electromechanical systems (MEMS) based on the electostatically actuated parallel plate concept and suitable for Voltage Controlled Oscillators (VCO) at RF frequencies is presented in this paper. The main objective of this work is to achieve a frequency tuning capability of high quality. The dimensions of the MEMS device have been optimized with the Finite Element Method based CoventorWare analysis software and verified through a lumped parameter analysis in a Saber platform. The varactor has been fabricated using gold-based surface micromachining process. Both the mechanical and electrical performance of the device have been verified using a lumped parameter analysis in a Saber platform. The mechanical response, electrical response and loss performance of the varactor have been experimentally investigated.

Keywords

MEMS, Varactor, VCO, Capacitance tuning ratio, Pull-in, SEM, Vibration spectrum, LDV

 

 

8.

MEMS and Smart Systems Development: Indian Scenario

Authors

V.K. Aatre

Affiliation

Former Director General, Defence Research & Development

Visiting Professor, ECE Department, Indian Institute of Science,

Bangalore – 560012.

Appears in

J. ISSS Vol. 1 No. 1, pp. 65-84, Sept 2012.

Abstract

The combination of smart materials and micro-electro-mechanics evolved as a strong platform for developing devices for safe and more comfortable human life. The science and technology evolved from these arenas paved the way for integrating smart electronics and smart mechanics. Globally this technology has already been accepted for developing advanced controls, sensors, actuators, smart systems in regular human life, aeronautics, automobiles and so on. Over the last decade through the two national programs, and internal programs of several Scientific Departments of Government of India, the Micro Systems and MEMS technology has reached a sizable maturity. These programmes have created significant infrastructural facilities and enhanced the human resource appreciably. Several devices have been designed, developed and tested for applications in aircrafts, automobiles and in biomedicine. Present article is a compendium of diversified activities spreading over different applications.

Keywords

Smart systems, Micro systems, MEMS, Shape memory alloys, Piezoelectric composites, Gas sensors, Magneto-resistive sensors, Structural health monitoring, National program on micro and smart systems