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INSTITUTE OF SMART STRUCTURES AND SYSTEMS (ISSS JOURNAL OF ISSS

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

Journal of ISSS 65

MEMS and SmartSystemsDevelopment:Indian Scenario

V.K. AatreFormer Director General,Defence Research & DevelopmentVisiting Professor, ECE DepartmentIndian Institute of Science,Bangalore – 560012.

AbstractThe combination of smart materials and micro-electro-mechanicsevolved as a strong platform for developing devices for safe andmore comfortable human life. The science and technology evolvedfrom these arenas paved the way for integrating smart electronicsand smart mechanics. Globally this technology has already beenaccepted for developing advanced controls, sensors, actuators,smart systems in regular human life, aeronautics, automobiles andso on. Over the last decade through the two national programs, andinternal programs of several Scientific Departments of Governmentof India, the Micro Systems and MEMS technology has reached asizable maturity. These programmes have created significantinfrastructural facilities and enhanced the human resource appre-ciably. Several devices have been designed, developed and testedfor applications in aircrafts, automobiles and in biomedicine. Presentarticle is a compendium of diversified activities spreading over dif-ferent applications.

1. Introduction

The history of technology clearly indicates thatthe 20th century, especially the second half of thecentury, saw more development during the hundredyears than that was seen in the last few millennia.There were several jewels of technology such asthe Laser, Supersonic Aircrafts, Satellites, GPS,Computers, World-wide-web, Cell Phone, etc.Without much exaggeration, it can be said that allthese were made possible by the developments inelectronic technology led by the discovery oftransistors and the development of IntegratedCircuits. Miniaturization and the ensuing very-large-scale-integration (VLSI) technologies caused thisunprecedented technological revolution of the 20th

Century. Towards the end of the century, primarilytechnologies based on silicon miniaturization wereextended to mechanical components such as beams,gears, pumps, motors etc. and led to anotherrevolution called, “Micro-machines”. Obviously, thenext step was to integrate microelectronics withmicro-machines, possibly on the same chip, and theresult was Micro-electro-mechanical systems, morepopularly known as MEMS. Coupled with thedevelopments that are taking place in SmartMaterials, materials that adjust their properties tosuit their functional environment, we arrive at theSmart Micro Systems. Smart micro-electro-mechanical systems are combinations of microsensors and actuators that can sense the

INSTITUTE OF SMART STRUCTURES AND SYSTEMS (ISSS) JOURNAL OF ISSS

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

Available online at www.isssonline.in/journal/01paper08.pdf Paper presented at ISSS InternationalConference on Smart Materials Structures & Systems, January 4-7, 2012, (ISSS 2012) Bangalore, India

65

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

environment and can respond intelligently tochanges in the environment by using micro-circuitcontrols. Clearly micro and smart systemtechnologies have immense potential forapplications spread over myriad of areas fromautomobiles to aerospace, from health sciences toenvironment, from cosmetics to consumer products.

In India though the application of electronic,materials and other technologies resulted in thedevelopment of defence, aerospace, automobile andother systems, however, the development of basicmicroelectronics technologies was rather slow and,indeed, was stymied due to the absence of requiredinfrastructural facilities. Recognizing that certainproactive actions are required to propel thedevelopment of Micro and Smart Systemtechnologies in India, led a group of Scientists andEngineers to form a Society called, ISSS (Instituteof Smart Structures and Systems) and mountedNational Programs to develop such technologies.This article briefly presents the collection ofdevelopments few selective areas.

2. National Programs

The first MEMS device to be fabricated inIndia was a pressure sensor developed at IIT,Chennai by Prof. K.N. Bhat. (See Fig. 1.)However, the formation of ISSS following the firstInternational Conference on MEMS and SmartSystems led to the initiation of several activities inthis field. One of them was the 5 year NationalProgram on Smart Materials (NPSM) whichinitiated modest R&D activities in materials anddevices besides establishment of basicinfrastructural facilities. The available Silicon ICfabrication facilities – using 1 micron technology –were certainly inadequate to cater for therequirements of VLSIs and ASICs and basicMEMS facilities were built around these existingfacilities. Several Design Centres with standardMEMS design software were started at academicinstitutions and the NPSM seriously considered thehuman resource development as one of its primaryresponsibilities. The second mainly applicationoriented national program – National Program onMicro and Smart Systems (NPMASS) – carriedforward the initial success of NPSM.

The three basic application areas identified by

NPMASS were Aeronautics (to cater for activeaircraft programs of DRDO and CSIR),Automobiles (to cater for the successful autoindustry in India) and Biomedical as perhaps themost important fields for application of micro ( andnano) technologies. As ‘Innovation’ fundamentallydepends on both technology and human resources,the national program continued to concentrate onmanpower development and training, besides a fewtechnology development projects through researchactivities at academic institutions. The entireactivities of the National Program was conductedthrough five Project Assessment and ReviewCommittees. In the remainder of the article coversthe technical activities of the National Program(NP).

3. Infrastructure and Human ResourceDevelopment

The necessity of infrastructure and humanresources in technology development need hardlybe emphasized. The NP, thus has made this one ofits primary goals. MEMS and micro systemdesigners have now four foundries to choose,namely, SCL (Chandigarh), BEL (Bangalore),CEERI (Pilani) and CMET (Pune). SCL catersfor 0.18micron CMOS facility in addition to thestandard MEMS facility and is deeply involved withseveral of the NP projects. The facility itself is runthough a separate Society under the Departmentof Space. Though the BEL facility is an in-housefacility, it is accessible to NP projects andcommercialization of products. CEERI has both6" and 3" facilities, the latter being used for training

MEMS and Smart Systems Development Indian Scenario

66INSTITUTE OF SMART STRUCTURES AND SYSTEMS

Figure 1. Photographs and characteristics of the firstMOSFET Integrated pressure sensor



Journal of ISSS 67

purposes. This facility is mainly for R&D work.The CMET LTCC (low temperature co-firedceramic) facility covers most of the requirementstowards RF and Microfluidics devices and relatedpackaging needs. These foundries have beenaugmented with essential equipment so that theymeet the future project/product requirements. Morerecently DRDO’s SITAR foundry at Bangalorehas established full-fledged MEMS foundry andwill shortly have packaging facility for the same.Recognizing the importance and requirements forBio-MEMs, a new polymer MEMS fabricationfacility is being created at SITAR with the help ofBIGTEC, a private organization dedicated tomedical and biological devices.

Since MEMS device characterization is aspecialized task requiring significant infrastructureand expertise, two major test and characterizationfacilities have been established. ‘Mechanical andMaterials Characterization’ facility (Fig. 2) is loca-ted at the Centre for Nano Science and Engineeringat IISc. This is a unique facility with a large numberof test and characterization equipment locatedcentrally. The equipment include Microsystemanalyser, Acoustic microscope, Rate table, Pressuresensor test zig, Field Emission SEMs, Dual beamFIB, and AFM. This facility is being used extensivelyby a large number of users and is run as an openaccess facility. The second facility for “RF andMicrowave MEMS characterization” has beenestablished at IIT Delhi, with a capability of highfrequency characterization up to 110 GHz.

A large number of National MEMS DesignCentres (NMDC) have been created in variousacademic institutes across the country to facilitatemanpower development. At present there are 64such centres partitioned into Resource Centres(IISc Bangalore, IITs at Bombay, Madras, Delhi,Kanpur, Kharagpur), Tier I and Tier II centres.These centres are equipped with Intellisuite,COMSOL Multiphysics and L-Edit design tools. Aselected few have access to Coventorware and R-

Soft tools. In order to create awareness onMicrosystems Technology, several workshopswere organized in collaboration with ISSS. Theworkshops (Fig. 3) held across India (Coimbatore,Pune, Shillong, Kurukshetra), also to provide hands-on design tool demos.

Another important HRD activity under the NPis hands-on training in MEMS devices processingat CEERI, Pilani. A selected group attending theworkshops are trained at CEERI 3" facility (Fig. 4)on various MEMS process modules. During thisperiod, the participants fabricate bulk micro-machined MEMS pressure sensors, starting frombare Silicon wafers. The participants also perform

Figure 2. Micro and Nano Characterization Facility, CeNSE, IISc Bangalore

Figure 4. Hand-on training in Progress at CEERIPilani

Figure 3. MEMS workshop at NEHU, Shillong

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post-fab processing – including dicing, packagingand characterized using a pressure calibrator.

Following paragraphs enlist various researchand development activities and are selected basedon their success status to realize a usable device,for a specific application.

4. Research & Development Activities

The research and development activity in NPis designed to identify projects pertinent toimmediate applications of aerospace, automotiveand biomedical engineering. Primary aim of thisactivity is to make rapid strides in developing variousapplications with improved performance of existingtechnologies and / or paving way for newerinnovations. Few selected projects are listed belowconsidering their maturity towards devicedevelopment and readiness for immediateapplication.

4.1 NiTiPt High Temperature Shape MemoryAlloys:

Shape Memory Alloys (SMAs) are used fordevelopment of thermal actuators in variety ofengineering applications. Among various alloysystems, binary NiTi alloys are the mostcommercially exploited ones because of theirsuperior shape memory, mechanical and corrosionresistance properties. However, the highestapplication temperature of binary NiTi alloys islimited to about 120ºC. In recent years, there hasbeen an increasing demand for high temperatureshape memory alloys (HTSMAs) for applicationsin aircraft turbo-engines, automobile engines, power

plants, automation, etc. Potential applications ofNiTiPt HTSMAs are adaptive (variable area/geometry) high-speed inlets, various flow controldevices, variable area bypass nozzles, fuel nozzlesand mixers, active clearance control devices forthe compressor section of aero-engines. One ofthe laboratories/institutes actively pursuing researchfor the development of HTSMA products foraerospace applications is GRC, NASA, USA incollaboration with Dynalloy, USA.

The present research work (at NAL,Bangalore) was undertaken with the objective ofdeveloping and processing NiTiPt HTSMA in wireform suitable for applications above 2000C.HTSMA of nominal composition Ni

30Ti

50Pt

20 (at.%)

has been successfully developed and processed intowire form with diameters in the range 263 - 500mm (Fig.5.(a)). The thermo-physical, mechanicaland functional properties of the developed wire(Fig.5 (b) and Table 1) are comparable or betterthan those reported in literature.

4.2 PVDF based composites films fortransducer applications:

Piezoceramics also have a large mechanicalquality factor (Qm) and require the addition ofdamping backings to reduce ringing to an acceptablelevel. Finally, ceramics are brittle, nonflexible andcannot be formed onto curved surface, limitingdesign flexibility of the transducers. Polymers suchas poly (vinylidene fluoride) (PVDF) and itscopolymer exhibit good flexibility which makes themvery attractive polymer. Despite having a very highvoltage coefficient, the low d

33 and d

h values and

need of an extremely high electric field, which limits

Figure 5. (a) Ni30Ti50Pt20 shape memory alloy wire of diameter 263 mm (properties in Table 1), and (b) strain vs.current (temperature) at 210 MPa stress





Journal of ISSS 69

Properties Targeted Achieved Literature

Transformation Properties

Martensite start (Ms) temperature : > 200°C 288°C 285°C

Transformation hysteresis (Af-M

s) : 25-35°C 27-28°C 11-30°C

Transformation strain : 2.0-3.0% 2.6-2.8% 1.9%

Mechanical properties

Young’s modulus : 30-40 GPa (M*) 31-32 GPa (M) 48 GPa (M)60-80 GPa (A*) 68-70 GPa (A) 58 GPa (A)

Ultimate tensile strength : ≥ 900 MPa (M) 1340-1800 MPa (M) 1550-1670 (M)≥ 900 MPa (A) 1100-1200 MPa (A)

Elongation to failure Martensite(fully annealed) Martensite(cold worked) : 10-15% 5-10% 14-16% 8-13% 8.2% 2.7%

* M: Martensite (low temperature phase, A: Austenite (high temperature phase)

Table 1: Properties of Ni30

Ti50

Pt20

HTSMA wires processed at NAL, Bangalore

the thickness of the material hinder their applicationin certain areas. Some composite needs to bedesigned which can utilize the best properties fromeach constituent phase to create an improvedtransducer material.

The goal of the present work was to developa new piezoelectric composite by critically blendingthe loading of PZT ceramic in the PVDF polymermatrix to serve as a flexible sensor. The primaryproperty for the reliable operation of a sensor wouldbe the electric field generated in a material per unitmechanical stress applied to it i.e. the piezoelectricvoltage constant (g

33). Figure.6 presents the

various PVDF and PVDF-PZT films developed inthis program with different silver patterns anddifferent edge connectors for various applications.

Figure 6. PVDF and PVDF-PZT films with differentsilver patterns and different edge connectors

The implementation was to focus on three focalareas: tuning the composite properties by controllingthe percentage loading of ceramic in polymer matrix,fabrication process to prepare the composites,validate the films for acoustic sensing applications.

A significant portion of the project involvedthe comprehensive understanding of the variationin the material’s intrinsic behaviour while varyingthe various parameters to finally identify the criticalprocess parameters. The result of this iterativeoptimization process are PVDF-PZT compositefilms with the tensile modulus and strength of 1253MPa and 24 MPa, respectively. Piezoelectric chargecoefficient prepared using solvent cast were foundto give a d33value of 40pC/N. Using the PZT chips,we could achieve a d

33 of 100 pC/N. The response

of these films for acoustic emission applications wascomparable to that of commercial acoustic sensor.

4.3 Acousto Ultrasonic Coating for StructuralHealth Monitoring

Development of Acousto-UltrasonicTransceiver on aerospace grade metallic andcomposite structures by novel technique of insitupiezoelectric coating for Structural HealthMonitoring (SHM) is the aim of this research(NAL). This methodology of coating directly on tothe test object is found to be superior to the bondedpiezo wafer as the ill effect of the intermediate

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adhesive bonding is completely avoided.

Ultrasonic transceivers have been developedby in-situ piezoelectric coatings on Aerospace gradeAluminum metal, CFRP and GFRP (regular andirregular surfaces) to function as transmitter andreceiver of Ultrasonic wave. The coating hasproved its usefulness in field applications byqualifying stringent tests. The performance ofPiezoelectric coating as ultrasonic transmitterrequiring low voltages (~10V) for excitation is betterthan that of commercial Piezo Wafer. Thedeveloped coating is found to be very promisingfor damage detection of Composite Structures(Delamination, Fibre separation, Fibre cut) and 2Dmetal components. Figure 7 (a,b,c) shows a typicalcomposite test object with piezo coating, introduceddefect (fibre cut) in the laminate and guided wavesignals for healthy and damaged composite laminateemploying Acousto Ultrasonic coating.

In recent years, piezoelectric waferspermanently attached to the structure have beenemployed to generate and detect guided waves forstructural health monitoring. The adhesive bondingbetween wafer and structural substrate is the weaklink in the sensory system due to its deteriorationwith time under environmental attacks. Also needof higher operating voltage (~150 Volts) to excitethese Piezo wafers for generating guided wavesrestrict their application for in-flight SHM.Piezoelectric thin and thick films operating at 10V

Figure 7. Composite Beam with Piezoceramic Coatings, (b) Defect (Fiber Cut, Fiber Cut + Fiber Separation)introduced in the Composite laminate. (c) Comparison of healthy and damaged signals from piezoceramic coatingS1 at 140 kHz.

could have replaced PWAS but for their poor piezoelectric performance and need for bonding makesthem unsuitable for real time SHM. With thedrawbacks associated with PWAS & thick/thinfilms, the present development of insitu PZT coatingis a breakthrough in real time applications and valueaddition to the field of SHM technology. The presentdevelopment directly leads to the application of in-flight Structural Health Monitoring. It is useful forMaterials Testing viz., porosity and densitydetection, internal bond strength prediction andrevealing anisotropy of composites aiding in Qualityand Process control. The developed technology canalso be used for Corrosion Detection, Oil viscositymeasurement and debris monitoring.

4.4 Development of a low cost ceramic gassensor system prototype for monitoring theair quality of automotive cabin.)

The primary aim of this project(IIT,Kharagpur) present proposal is to evaluatethe CO, HCs and NOx sensing characteristics ofnano-structured composite perovskite: spinel andmodified binary oxide to monitor the air qualityof automobile cabin. The objective of the presentresearch is to synthesize these sensing materials inthe form of nano-powder, thin film and nano-rodsor tubes and understand the mechanism that controltheir sensing characteristics in terms of sensitivity,selectivity, response/recovery times and stability.Finally, using the optimized sensing materials we





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have proposed to fabricate a microcontroller basedprototype gas sensing system.

Significant achievements include, a) Synthesisand characterization of nano-structured thin filmand nano-tubes of the proposed sensing materials.Fig. 8 (a) shows the surface morphologies of someof the synthesized oxide sensing elements in theform of pellet, thin film, embedded and isolated nanotubes. b) Development of a portable quasi-dynamicflow sensing chamber, micro-controller basedelectronic circuit module, data acquisition andanalyses software for gas sensing measurements(Fig.8(b). c) As shown in Fig. 8(c) that thedeveloped sensing elements are capable of detectingNO

x (0.1-10 ppm) (using WO

3thin film), CO (2-10

ppm) (with 0.5 La0.8

Pb0.2

(Fe0.8

Co0.2

)O3 -0.5

Mg0.5

Zn0.5

Fe2O

4 bulk composite) and C

mH

n (20-500

ppm) (WO3 film) gases. Sensing of these gases in

said concentrations are very important to developsensing system to monitor air quality in automotivecabin, and d) Fig. 8(d) shows that for H

2, CO mixed

gas with different concentration ratios, patternrecognition analyses is very effective for distinctclassification.

The present research has three majorcomponents namely: synthesizing of sensing

Figure 8. Development of magneto-resistive sensors technology for application in aerospace systems

material, understanding their gas sensingcharacteristics, and development of sensingsystem (consisting sensing element and an micro-controller based electronic module) for selective gasdetection. If our approach is professionallydeveloped then this indigenous technology wouldcompete the global leaders (viz. Figaro Inc.) Theultimate application of the proposed research is tomake sensing system for monitoring the air qualityof an automotive cabin.

The project at NAL aims at the developmentof Gear tooth (GT) sensor using GiantMagnetoresistance (GMR) based magneticmaterials for automobile application. Theprogramme successfully deposited CoFe/Cumagnetic multilayers with varying CoFe thicknessand maximum GMR obtained 8 % with CoFethickness of 1.3 nm and Cu thickness 2.5 nm. Thesensitivity of these sensor was found to be 0.08 %/G and the measured hysteresis was negligible ( <10 G). These sensor was found to be stable at180 0C in air. We have also fabricated Gear Tooth(GT) sensor on Si substrate using these GMR films.These sensors showed a promising potential fortesting to measure the RPM of a rotating shaftand can be used in automobile sector for

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development of digital speedometer. The highestsensitivity of GMR materials (Ta/NiFCo/[CoFe/Cu]

15/Ta) with thermal stability up to 225

oC was reported by Non Volatile Electronics,USA 0.1 %/G. The results obtained in thepresent project are comparable to the reported one(Fig.9). These sensors can be used to developspeed sensors for Automobile Applicationswith Magneto Resistive Element (MRE)Technology.

Figure 9. GMR based Gear Tooth sensor fabricated onSi substrate. Inset shows magetoresistance propertiesof the film annealed at different temperatures.

v) Optical and nano-based devices for bio-medicine

The main goal of this project at Indian Instituteof Science was to develop a multidisciplinaryapproach towards bringing experts from variousfields together, namely nanotechnology, biology andphotonics, with a special emphasis towardsdeveloping modules for sensing minute quantitiesof bio-pathogens and developing bio-manipulationtechniques for measuring micro-rheologicalproperties of single proteins and muscle cells. Theproposed bio-sensing modules were optical in nature,in particular those based on nano-photonicsconcepts, such as localized surface plasmonresonance (LSPR).

Significant progress has been made indeveloping a low cost, wafer scale technique indeveloping SERS (Surface Enhanced RamanScattering) substrates, which have a very high limitof detection. The key innovation in the presentmethod has been to use multiple layers of plasmonic

nanoparticles in porous films, which results in a verylarge number of hot spots with high electromagneticfield enhancement. The resultant substrate has alarge available surface area, as well as a high EF(Enhancement Factor), within the illuminationvolume. Preliminary measurements in thesesubstrates show an EF of 107-108 with an effectivesurface area that is orders of magnitude higher thana regular 2D substrate. As a result, the performanceof the SERS substrate is unprecedented withrespect to all other SERS (3D or 2D) substrates(Fig. 10). Interestingly, this substrate is unique inwhich both fluorescence and Raman signal werefound to be enhanced, which can have majorimplications in sensing applications. Present findingstowards the development of a low cost SERSbiosensor, specifically targeted towards bio-pathogens like Salmonella, as well important bio-molecules like Thrombin.

Figure 10. (Left) Schematic of a 3D porous array ofplasmonic nanoparticles, here Ag, separated bydielectric rods, here SiO

2. (Right) SEM image of the

fabricated array.

5. Aerospace Applications and StructuralHealth Monitoring

MEMS (sensors and actuators) and Smartsystems find wide application in aircrafts, spacevehicles, especially in Structural Health Monitoring(SHM) Systems. Indeed , one of the earliestapplication of MEMs was in Indian SatelliteProgram. Several initiatives like DISMAS ofAeronautical Development Agency (ADA),MEMS program at ISRO, and work on SMAs(shame memory alloys) of National AerospaceLaboratories of CSIR addressed certain aerospaceapplications. The main aim of the NP in aerospace





Journal of ISSS 73

was to complement the work in the earlier initiativesand gravitate towards products for current andfuture national activities in aerospace andsimultaneously look at SHM systems for bothaerospace and civilian structures. Specifically NPaddressed the requirements of:

- MEMS Device Development- Pressuresensors, Accelerometers and Gyroscopes;

- RF MEMS devices Development forswitches, varactors, phase shifters and theirintegration in T/R modules;

- Smart actuator development using Piezostacks;

- Smart application for vibration and noisecontrol, morphing of wings;

- Rapid NDE techniques for SHM

- Integrated Vehicle Health Monitoring

One of the major differences the currentNPMASS program has over other Governmentfunded projects is the involvement of Indian privateindustries and foreign universities in the technologydevelopment. The sanctioned projects include fourprivate industries (Cranes Software, MahindraSatyam, Tata Consultancy services and AstraMicrowave Products Ltd. (AMPL)) and oneuniversity from abroad (Georgia Institute ofTechnology, Atlanta, USA). .

In the area of device development, MEMSAccelerometer is being developed at IITKharaghpur, Inertial MEMS (Gyroscopes) at IIScand CEERI Pilani, RF switches for phase shiftersat AMPL(IIT-Delhi), IIT Chennai and CEERIPilani, while RF Veractors development is taken byIIT Kharagpur. Though the device designs isundertaken by the academic institutes, devicefabrications is being undertaken by SCL, CEERI,and SITAR. M most of the devices would caterfor the requirements of ADA and RCI ResearchCentre Imarath). Recently a subsystemdevelopment of Air data probes for India’s LightCombat Aircraft has also been initiated. Gyroscopesand Inertial sensors are very important in aerospaceand development of these have been undertaken inthe NP. Fig. 11 shows the first four naturalfrequencies of a 4 beam proof mass accelerometer

developed at IIT Kharaghpur. To cater for therequirement of Defence laboratories specificPressure sensor projects have also been initiated.Tables 2 to 4 indicate their specifications.

Table 2

Table 3

Table 4

Under smart application area, some of theapplications being are:

l Active Vibration Control of SARAS (NALproject) aircraft Engine mount

l Development of Active noise controlled Helmetfor TEJAS (LCA) aircraft cockpitt

l De-icing methodology using Smart piezoactuation

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l Aircraft wing morphing using smart actuation,and

l Trailing edge flap actuation for exterior noisecontrol for Advanced Light Helicopter (ALH)developed at HAL

Figure 12 shows the experimentaldemonstration of morphing of the NACA 4421airfoil using Peizo stack actuators. This workis currently done at Indian Institute ofScience,(IISc) Bangalore while the peizo stackactuator development is undertaken by NAL andCGCRI, Kolkata. A class actuators developed bythese institutions have a range of block force (400

Figure 11. First four natural frequencies of a 4-beam proof mass accelerometer

(a) Before Morphing (b) After Morphing

Figure 12. Wing Morphing demonstration of NACA 4421 airfoil

N-8000N) and a range stroke lengths (10 �m to90�m).

SHM development is mainly oriented towardsdevelopment of off-line technology, which arerequired for reducing aircraft maintenancesignificantly. Some of the technologies developedinclude development of non-contact Laser DopplerVibrometry (LDV) based SHM, Rapid NDEmethods such as air coupled ultrasonics, Piezo arraybased damage detection method, the developmentof FBG based interrogation system for highfrequency SHM applications and more recently, thedevelopment of SHM centric software that





Journal of ISSS 75

integrates both NDE and SHM protocol. Thissoftware package development is being undertakenjointly by Mahindra Satyam, IISc and IIT, Madras.When developed, this software will be the first ofits kind in the world that will be completely centricto off-line SHM, which will include all NDEmethods of damage detection and will completelyintegrate with MRO operations of aircraft fleetswith SHM.

Figure 13 shows the presence of delaminationand debonds in a T-composite joint using LDV. Thiswork, undertaken at Indian Institute of Science hasGeorgia Institute of Technology, Atlanta, USA, asits collaborator.

NP has initiated a project on developing aMicro systems software module for MEMSstructure analysis and design. This software isexpected to have all features of other MEMSsoftware such as Coventerware, Intellisuite etc. Thissoftware module will use NISA finite elementsoftware developed by Cranes Software, Inc. asits engine.

6. Automitive Applications

Since 1980, there has been an ever increasingpenetration of electronic control systems andelectrical components in automotive products.These systems can be categorised into areas ofpowertrain and chassis control, comfort andconvenience and communications. Each of thesesystems requires specific set of low-cost sensorsand actuators. Most of the commercial automotive

Figure 13. SHM of a composite t-Pull Joint using LDV

activity for MEMS technology has been in thesensors area. Actuators having MEMS parts arestarting to emerge as ways to fabricate intricateparts. The projects taken up under the NP fall intothree categories: Pressure Sensors, Gas Sensorsand Hall Effect based Sensors. The MAP (Manifoldabsolute pressure) sensor falls in the first category.

6.1 MAP Sensor:

Here the main aim was to develop both MAPand TMAP Sensors for Automobile Applicationsand package it for its ultimate use in automobileinstrumentation systems. With a view toproductionise the same, Pricol Ltd. Of Coimbatorewas inducted in to the project at the beginning itself.Pricol is already producing various variants ofPressure Sensors, Speed Sensors, TemperatureSensors, Temperature Switch cum Sensors andPressure transducers, Cam & Crank PositionSensors, Throttle Position Sensors & Actuators etc.The development of MEMS pressure sensorelements, integration with required ASIC for MAPand integration of temperature sensor for TMAPwere done by SCL; while Pricol’s responsibilitieswere development of Sensor housing and adaptorwith requisite span and offset and temperaturecompensation, packaging and testing. .

The sensor, in its various stages of fabrication,is shown in Fig. 14. Table 5 gives the specificationsof the sensor.

The development work is now complete andindustrial prototypes have successfully undergone

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Pressure range 13.332 to 119.99 kPa

Over pressure 490 kPa

Supply voltage 5 ± 0.5 V

Output voltage 1 to 4.2 V

Body material PBT 30% GF

Input voltage 5 ± 0.25 V

Table 5: Sensor Specifications

Figure 14. MAP Sensor Fabrication Stages

the all the required - general performance, excessivepressure, gasoline resistance, high temperature high

humidity storage, low temperature storage, drop,thermal cycle, High temperature, high humidityoperation, high temperature operation, thermal cycleoperation, high temperature storage, lowtemperature operation, vibration, water resistance,salt spray and exhaust condensed water test. Actualcommercialization is just round the corner.

6.2 Gas Sensor Platform

This multi institutional project aims at thedevelopment of Zinc and Tin Oxide film basedsensor for exhaust gas monitoring in automobiles.The various features of the sensor are shown inFig. 15.

Figure 15. Gas Sensor

Various subsystems being developed for thisplatform are:

1. Design of micro-heaters and synthesis andcharacterization of SnO

2 and mixed oxide films with

specific dopants for methane and hydrogen gassensing.

This project is being done at IISc Bangaloreand it aims at (i) Development of Tin oxidefilms with dopants for Methane and Hydrogensensing (ii) Development of MEMS basedmicro-heaters at the Proof of Concept level. Threedesigns have been developed and ten prototypesfor each design have to be delivered (iii) Selectivesynthesis and characterization of SnO

2

nanostructures in the form of thin films (iv)Exploring the effect of substrate temperature,deposition rate, carrier gas pressure and annealingon the yield and growth of nanostructures of SnO

2

(v) Demonstrating the effect of surfacefunctionalisation on gas sensing properties of SnO

2

thin films (vi) Optimize process parameters forrequired sensitivity and selectivity;





Journal of ISSS 77

2. Growth and characterization of compositematrices of Zinc oxide thin films with dopants-CO

2,NO

2 and SO

2.

This project is being done at the University ofDelhi and it aims at (i) Development of Sensingcomposite matrix of ZnO thin film with suitablecatalyst (ii) Selective synthesis and characterizationof ZnO nanostructures in the form of thin films (iii)Exploring the effect of substrate temperature,carrier gas pressure and annealing on the yield andgrowth of nanostructures of ZnO (iv)Demonstrating the effect of surfacefunctionalisation on gas sensing properties of ZnOthin films (v) Obtaining optimized processparameters for required sensitivity and selectivity;

3. Fabrication of MEMS Microheater forAutomotive Gas Sensor.

This project is being done at CEERI Pilani and itaims at up-scaling and development of batchprocessing of the “proof-of-concept microheaters”developed at IISc Bangalore in the first project.The deliverables are 25 wafers of Microheatersfor gas sensor fabrication (in the form of processed4" dia. wafer or chips);

4. Design and Development of Microsystem

Platform for Gas Sensors Using General PurposeASIC Devices.

This project is being done at IISc Bangaloreand its objective is to develop a Gas Sensor withcommercially available sensing element chip andASIC. It is expected to deliver ten prototypes offully built sensors for one target gas;

5. Miniaturized Gas Sensors for Hydrogen and othergases.

This is a futuristic project being done at IITKanpur on nano silicon sensors for gas sensing.

6.3 Hall Sensor Projects

Hall Effect based sensing with the final aimof position and speed measurement have beenundertaken.

1. Development of GaAs Based Hall Elements atChip Level for Automotive Applications

It aimed at development of the fabricationprotocol for Gallium Arsenide element chips onAlumina substrate. Activities involved LayoutDesign and Mask fabrication, Reactive Ion etching,Development of Ohmic contacts and Testing atvarious levels. The chip is shown in its variousstages of fabrication in Fig. 16.

(c) Hall Chip after electroplating and scribing (d) Hall Chip mounted on alumina substrate

(a) Hall Chip after MESA etching and ohmie contact (b) Gold patterned alumina substrate

Figure 16. GaAs Hall Effect Chip

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2. Hall Sensors for Automotive Applications

This project successfully completed atIIT Kanpur involved using commercially available,off-the-shelf sensor chips and to develop (i)RPM/ Speed Sensors, (ii) Crankshaft Sensors and(iii) Pedal Position Sensors for automotiveapplications.

The following components (Table 6) were used

Table 6: Hall Elements

No. Component Name Description

1 Hall Sensor ATS643LS (2 pin)

ATS667LSG (4 pin)

2 Hall Element SJ 119 (GaAS typehall element)

TY101A (InSb typehall element, smd)

3 Magnet Rare earth type

Electronics and Packaging for the sensorshave been developed and calibration has beencarried out on different automobiles. The sensorsare shown in Fig. 17.

Figure 17. Hall Element Sensors

Wheel Speed Sensor Pedal Sensor

Crankshaft Sensor

6.4 IVHM Projects

In addition to the three sensor platforms

discussed here, several projects on IntegratedVehicle Health Monitoring (IVHM) have beentaken up for application in aircrafts and automobiles.The aircraft based projects are just underway, whilethe automobile based projects have progressedsatisfactorily.

This goal of the Integrated Vehicle HealthManagement (IVHM) program is to equip vehicleswith on-board and off-board smart sensors andalgorithms to enable diagnosis, prognosis andisolation of faults. The challenge associated withIVHM is the poor observability in vehicles, both inthe automotive and aerospace industry. This ismainly due to the lack of durable and affordable,high performance sensors. The IVHM programwill develop a set of vehicle and sub-system leveltest stands that will enable development, testing andruggedization of smart sensors that can meet theneeds of the automotive industry. In addition, theprogram will develop algorithms that complimentthese sensors to develop an end-to-end, smartsensor based prognostic solution for vehicle healthmanagement. The primary focus of the smartsensor based IVHM program is to improve thefollowing vehicle performance metrics: (i) Fuelefficiency (ii) Emissions (iii) Safety (iv) MaintenanceCost.

The following sub-systems of an automobilehave been initially taken up – (i) Brake system (ii)Steering system and (iii) Engine. Projects on Brakeand Steering System are being done by IIT Kanpurand the Engine System project is being executed atIIT Kharagpur.

The Steering and Brake System Test Bedsdeveloped at IIT Kanpur are shown in Figs.18(a),(b) and the Process-in-Loop Tests and theHarnessing activity schemes are shown in Figs.19(a), (b) respectively. Work is currently, in progressat both IITs on instrumentation and algorithmdevelopment.

The development and implementation ofIVHM is gaining momentum and it is anticipatedthat it may be a standard fit in the coming decade.

7. Biomedical, Food and EnvironmentalSciences

It is believed that the micro (and nano) have





Journal of ISSS 79

(a)

* Overall dimensions: 1m wide x 3.6m long x 1.5m tall

* Total weight: 220 kg

* Tests right-hand side front and rear wheels

* Bracketry mimics car body mounting points using actual suspension parts

Figure 18. (a) Steering System Test Bed and (b) Brake System Test Bed

greatest potential for application in biomedical fieldcovering diagnostic (especially point-of-carediagnostic) devices, drug delivery systems andpatient health monitoring systems. Also micro fluidicand lab-on-a-chip devices are more applicable in

this area. Devices for food and environmentalmonitoring are similar in nature and share largecommonality with biomedical devices. Recognisingthe importance of this area, the NP has mountedseveral programs in development of such devices.

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(b)



Figure 19. (a) PIL Scheme for Engine and (b) Harnessing for Engine-ECU

(b)

(a)



Journal of ISSS 81

One of the earlier devices attempted for labon Chip for cardiac diagnostics. The currentunderstanding on the biomarkers for acutemyocardial infarction (commonly called heartattack) is the liberation of fatty acid binding protein(FABP), troponin and myoglobin within 1 – 3 hoursof the potentially fatal incident. Diagnosis on thebasis of biomarkers assumes significance as thepatient cannot be subjected to stress or any invasiveprocedures at that juncture. The development (atIIT, Bombay) is ready for field tests.

The technology consists of use of micro-cantilevers coated with the antibodies to the aboveproteins and a drop of serum on this cantileverinitiate reaction culminating in the deflection ofcantilever. The changes include surface charge,intermolecular energetics, molecular density andconformational changes. The deflection ofcantilever produced by these changes is measuredpiezo-resistively using appropriate electronics. Afterinitial experiments on silicon micro cantilevers, thedevice is now made on polymer (SU8). Thesemicro-cantilevers have the advantage of lowerYoung’s modulus, less expensive fabricationprocedures, compatibility for integrating sensor withmicro-fluidic components.

Fig. 20 shows the functional architecture ofthe device, and the schematic representation ofmicro-cantilever deflection is given in Fig. 21. Atpresent, the researchers have demonstrated theeffect of biomarkers troponin and FABP, theexperiments on myoglobin is in progress and testedthe device (Fig. 22) in the laboratory and awaitingclinical trials.

As part of this project, another device basedon surface Plasmonic resonance principle was alsodeveloped at the same institution.. The phenomenonwas demonstated with typical results as shown inFig. 23, with various concentrations of Sucrose. Thisdevice basically can be used for teaching andexperimental purposes (Fig. 24).

Development of a bio chip for testing antibioticsensitivity of pathogens of urinary tract” is alsounder way (BITs, Pilani). The project is of greatsignificance to our country as many women sufferfrom urinary tract infections. The gold standardfor testing the antibiotic sensitivity is by using culturemethod and the standard procedure takes 36-48hours for a final result. This project is an efforts atfinding quicker solution. The approach is toconcentrate the urine samples using disposable 0.2

Figure 20. Functional architecture of the device

Figure 21. Schematic representation of microcantilever deflection Figure 22. Reaction Chamber &Hand held Device

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iSens

micron cartridge leading to a loading trough, whichis then connected to a disc containing 10 growthchambers of 2 mm diameter and 8 mm height,through micro-fluidic channels of 50 and 100microns respectively in two separate discs (Fig. 25).In these chambers of 30-50 micro-litres volume,the urine sample will contain 200-300 bacteria. Thepoint-of-care device being developed, comes witha ready to use kit for rapid culture of pathogenspresent in the human urine sample and tests a panelof antibiotics for their bactericidal /bacteriostaticeffect on the pathogens present. This device offersease of operation and analysis of results, rapidresults at the bedside or in doctors’ chambers/labin less than two hours, reliable comparable toconventional disc assay and affordable cost per test.

The growth of the bacteria is monitored usingdissolved oxygen sensing, which is done by anoptical fibre probe dipped into each growth chamber.Within an hour, doubling of bacteria takes place inchambers where the bacteria is not susceptible tothe antibiotic, thus the sensitivity of the specimencan be diagnosed. However, to be on safer side,one can wait one or two more doubling, and a veryaccurate result can be made within 2-3 hours. Theclinical isolates of suffering women were tested forcommonly used antibiotics such as penicillin,ampicillin, gentamycin, kanamycin, cefuroxime andciprofloxacin.

The device provides for growth of pathogensin a specially designed medium ensuring rapidgrowth with release of a product linearly related tothe number of bacteria present. In the instance ofthe bacteria being sensitive to any given antibioticthe chromogen is not released. The released

Figure 23. Sensing Changes in Refractive Index Figure 24. SPR based device

chromogen is read out using a specially fabricatedreadout-machine(Fig. 26), based on a color tofrequency conversion, giving both an alphanumericdisplay on a screen and a print out for permanentrecord of the report.

Figure 25. Loading trough containing growth chambersfor bacterial multiplication

Figure 26. Prototype device -Uro Pathogens sensor





Journal of ISSS 83

The microfluidic liquid assay has been testedon more than 200 patient urine samples collectedfrom various hospitals in Pilani and Hyderabad.Device is being developed in two phases. The firstphase, which has already been completed, consistedof lab scale testing of the engineering version ofthe device.

During the second phase a multi-centric trialis planned at 3-4 locations for final validation of theassay.

A device for explosive detection has beencrying need for quite some time. This chemicaldevice is developed on the same basis of gassensors but by using amplified fluorescent polymers,a new route (IIT, Bombay). The device has beentested at HEMRL (DRDO Establishment) at Pune.More devices are under fabrication for multicentretrials. This devic can detect RDX and TNT, withina metre, without any direct contact. The The deviceuses a AFP’s (Amplified Fluorescent Polymers) asthe sensing element. It consists of an excitationsource (LED: Light Emitting Diode) emitting lightin wavelength range of 380 to 440nm. The LEDsource is focused on to a thick walled glass capillarytube coated with the AFP. The polymer emits lightin wavelength range of 450 to 490nm. A miniaturepump samples vapour through the capillary. Thefluorescence from the polymer is detected by aphotomultiplier tube (PMT) with an appropriateoptical filter. An amplifier circuit amplifies the outputsignal from the PMT. This device consists of threemajor modules – the sampling/detection module,detection electronics and a controller runningembedded software controlling all functions of thedevice including display.

First set of prototypes (Fig. 27) are beingmodified by replacing PMT with photodiode andappropriate amplifier circuit for fluorescence

detection (Fig. 28). This includes the modificationof detection/optics module to improve the flow ofvapour through the capillary to improve theperformance, Incorporation of a flow sensor fordetection of blockage in the air flow path throughthe capillary and replaced fan based suctionmechanism with a miniature pump.

Figure 27. First prototypes of BEAGLE

Figure 28. Second set of prototypes- BEAGLE

8. The Way Ahead

Over the last decade through the two nationalprograms, and internal programs of severalScientific Departments of Government of India, theMicro Systems and MEMS technology has reachedcertain maturity. We have created some, althoughinsufficient, infrastructural facilities and enhancedthe human resource appreciably. Several deviceshave been designed, developed and tested forapplications in aircrafts, automobiles and inbiomedicine. A few private industries have joinedacademic groups and national laboratories inproducing prototypes. It is expected that some ofthe devices will be packaged and commercializedin the coming months. Yet, the efforts are insufficientto make any appreciable impact. For this to happenit is essential for many more industries to recognizethe importance of this highly application orientedtechnology and for the academic institutions andNational laboratories to enhance their efforts inR&D resulting in devices and subsystems at thesame time increasing the human resources. Ofcourse, government has to make substantiallyincrease funds for R&D and infrastructure.

Acknowledgements

The technology reported here is the outcomeof dedicated work of a large number ofresearchers, scientists and engineers too numerous

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to be named here. The author gratefullyacknowledges and appreciates their work. Thearticle could not have been put together withoutthe contributions from the Chairmen of PARCs.The author owes his indebtedness to Profs.Navakantha Bhat, S.B.Krupanidhi, S.Gopalakrishnan, N.S.Vyas and Lazar Mathew. TheNational Programs were funded by DRDO and runby ADA. The authors thanks Program directorADA and the immense contribution of Dr. Vijayrajuand Sudhakar of the program office.

Dr. Vasudev Kalkunte Aatre obtained hisBE(Mysore) in 1961, ME (IISc)in 1963 and PhD (Waterloo,Canada) in 1967 all in electricalEngineering. He worked asProfessor of ElectricalEngineering at TechnicalUniversity of Nova Scotia,Canada from 1968 to 1980. He

was a Visitng Professor at the IISc in 1977. In 1980he joined DRDO.

Dr Aatre worked in India’s Ministry of Defence inthe Department of Defence Research and



Development as a Principal Scientific Officer(1980–1984), Director of Naval PhysicalOceanographic Laboratory (1984–1991), ChiefController (1991–1999), and Director General ofDRDO and Scientific Advisor to Defence Minister(1999–2004). During this period he designed anddeveloped sonar suites for surface ships,submarines and the air arm of the Indian Navy. Hewas also instrumental in the development ofintegrated electronic warfare systems for the IndianArmy, Navy, and Air Force, and he establishedGaAs MMIC fabrication and VLSI design centersfor Ministry of Defence. Dr. Aatre is the foundingpresident of the Institute of Smart Structures andSystems (ISSS) and has been running nationalprograms on smart materials and MEMS. He haspublished over 60 papers in the fields of activefilters, digital signal processing, and defenseelectronics, and has written a book entitled NetworkTheory and Filter Design published by John Wiley& Sons. He is a Fellow of the IEEE (USA) andthe National Academy of Engineering (India), aDistinguished Fellow of IETE (India) and severalother societies. Dr. Aatre is the recipient of theprestigious Padma Bhushan Award of theGovernment of India.

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