By Mr. Saradindu Ghosh

8/14/2019 By Mr. Saradindu Ghosh

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By

Mr. Saradindu Ghosh

MTB/09/1029


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First of all, what is MEMS ?MEMS stands for MicroElectro Mechanical Systems. It is a technique of combining Electrical and Mechanical

components together on a chip, to produce a system ofminiature dimensions ..

By miniature, we mean dimensions less than the

thickness of human hair !!!!


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Figure 5.1: JonathanSwift.Courtesy Sandia National Laboratories, SUMMiT Technologies,

www.sandia.gov/mstc.

Drive gear chain and linkages, with a grain of pollen(top right) and coagulated red blood cells (lowerright, top left) to demonstrate scale.


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The Scale of Things.

Introduction, Continued


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MST - Microsystems Technology (European)

MEMS - Microelectromechanical Systems (U.S.)

Manmade devices created using compatiblemicrofabrication techniques that are capable of

Converting physical stimuli, events and parameters toelectrical, mechanical & optical signals

Performing actuation, sensing and other functions

Introduction, ContinuedDefinition and Terms


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Spider mite with legs on a mirror drive assembly.

Introduction, Continued

Image Courtesy of Sandia National Laboratories, SUMMiTTM Technologies,www.mems.sandia.gov


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1962 Silicon Integrated piezo actuators BY O.N. Tufte et al.

1967 Anisotropic deep silicon etching H.A. Waggener

1967 The resonant gate transistor by H. Nathanson, et.al

1972 National Semiconductor - Pressure Sensor

1979 Thermal inkjet technology is invented at HP laboratories

1982 Silicon as a Mechanical Material K. Peterson

1982 Liga Process (KFIK, Germany)

1983 Infinitesimal Machinery R. Feynman

1983 Silicon Micromechanical devices J.B.Angel etc.

1983 Integrated Pressure Sensor Honeywell

1985 Airbag Crash Sensor

1987 Dr. Hornbeck Digital Micromirror Device or DMD (DLP by Texas Instruments)Later in 1990s micromachining begins leveraging microelectronics industry

1993 Accelerometer integrated with electronics Analog devices

1994 DRIE Etching (Bosch process is patented)

1999 Optical network switch - Lucent

Brief History


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Electromechanical Systems functional block diagram.

Electromechanical SystemsFunctional Block Diagram


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MEMS

Practice of making and combining miniaturized

mechanical and electrical components

Micromachines in Japan

Microsystems Technology in Europe


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Materials

Crystallography Forms of SiliconAmorphous

PolycrystallineCrystalline

Miller Planes

Miller Indices, Direction Examples

MEMSMicrostructure Fabrication


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Pattern definitionPhotolithography

DepositionOxidation, chemical-vapor

deposition, ion implantationRemovalEtching, evaporation

-Structural layer-Sacrificial layer

deposit

pattern

etchMicrostructure Fabrication

MEMS, ContinuedMicrostructure Fabrication, Continued


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MEMS, Continued

Processing Techniques

Deep Reactive Ion Etching (DRIE)

Surface Micromachining

LIGA process Lithography / Electroplating / Molding

SUMMIT process

Microstructure Fabrication, Continued


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MEMS Advantages

The advantages of MEMS devices include

Size

High sensitivity

Low noise

Reduced cost

Batch Processing

The applications for MEMS are so far reaching that a multi-billion

dollar market is forecast. Key industry applications includetransportation, telecommunications and healthcare.

MEMS, Continued


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The wonder called

nanotechnology

Nanotechnology is the technology of arranging atoms and

molecules in a material.

This allows to alter the properties of a material and build

structures of desired features.

A nanometer is one-billionth of a meter.

Nanotechnology makes it possible to manufacture devices

80,000 times smaller than the thickness of human hair !


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A simple analogy..The atoms in an object can be

compared to the blocks in abuilding game.

In a building game, the blockscan be arranged to createdifferent looking structures.

Similarly, atoms can bearranged differently toproduce a multitude ofdevices. This forms the basisofnanotechnology.


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Benefits of MEMS andnanotechnology in medical

applications Small volume of reagent samples (like blood),

required for analysis. Low power consumption, hence lasts longer on the

same battery. Less invasive, hence less painful. Integration permits a large number of systems to be

built on a single chip. Batch processing can lower costs significantly.

Existing IC technology can be used to make thesedevices.

Silicon, used in most MEMS devices, interferes lesserwith body tissues.


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Can MEMS devices really replace

the existing medical devices ?

A lot of MEMS medicaldevices have been

developed that are muchmore sensitive and robustthan their conventionalcounterparts.

Market trends for MEMS

medical devices show apromising future ahead.

http://www.sensorsmag.com/articles/0497/medical/main.shtml

www.edmond-wheelchair.com/ bp_monitors3.htm
http://www.sensorsmag.com/articles/0497/medical/main.shtmlhttp://www.edmond-wheelchair.com/bp_monitors3.htmhttp://www.edmond-wheelchair.com/bp_monitors3.htmhttp://www.sensorsmag.com/articles/0497/medical/main.shtml


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Projected MEMS market share

in 2009

Medical 11

Automotive 17

Computer 26

Communiction

21 %

Industrial 22

Consumer 3

http://www.memsindustrygroup.org/industy_statistics.asp
http://www.memsindustrygroup.org/industy_statistics.asphttp://www.memsindustrygroup.org/industy_statistics.asp


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Classification of biological MEMS

devicesBiomedical MEMS deals in vivo, within the host body.

precision surgery Biotelemetry Drug delivery Biosensors and other physical sensors

Biotechnology MEMS deals in vitro, with the biologicalsamples obtained from the host body.

Diagnostics

gene sequencing Drug discover pathogen detection


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Biosensor statusThere are many promising systems on the horizon,

but the only commercially-deployed biosensorsare glucose monitors (~$4B). 3 main types:

Single Use: Disposable sensing material, oftenstatic measurement. Cheap and portable, butlow sensitivity and accuracy.

Intermittent Use: Often use hydrodynamics generally much better performance from sensinga moving fluid. Its still a challenge to move theseout of the lab and onto a chip.


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Biosensor statusContinuous (In Vivo) Sensors: Very economical,

but very hard to calibrate and may suffer fromunknown amount of drift.


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Biosensor design While these were originally fabricated in silicon

using MEMS techniques, the trend is towardglass and plastic as the substrate.

Both glass and many plastics allow opticalmeasurements, but silicon is opaque to visiblelight.

Glass and plastic are also more resistant tocontamination from the chemicals used in themeasurement.


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Biosensor designSurface immobilization:The first step is sensing

is creating a selective surface to react to thesensed agent


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Biosensor designBead immobilization: A variation that uses beads

to increase relative surface area.


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Biosensor designDetection: Several methods, including resonant

frequency of MEMS cantilevers. Butamperometry (current measurement) is the mostwidely used approach. Typical mechanisms for

current flow include redox cycles between thetarget group and variants.


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Biosensor designOptical Detection: A 2D

array of agent/antigenreactions producesfluorescent traces:


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Biosensor designMagnetic Detection:The antibodies are

immobilized on a surface and magnetic beadsbind to sites where the analyte is attached.


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Enzyme-Linked ImmunosorbentAssay


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ReuseMost immunosensors use bound antibodies andimmobilization. Removing the bound species can bedifficult without destroying the sensors.

Methods and results vary, but a recent detector forChagas disease used glycine-HCl to wash thesensor, and reported efficacy for more than 30cycles.


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Biosensor designSystems-on-a-chip: are promising but coming

slowly. Biosensing still seems a long way fromcommercial viability. But there are somepromising prototypes:


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A Field Effect Transistor An optical

micrograph

showing the gate,

source, and drain ona pMOSFET device.

The Scale is L/W

20m/220m


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MEMS and drug delivery


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A Graphical Representation of nanorobots working in ablood vessel, to remove a cancerous cell

www.e-spaces.com/portfolio/ trans/blood/
http://www.e-spaces.com/portfolio/trans/blood/http://www.e-spaces.com/portfolio/trans/blood/


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MEMS microneedles MEMS enables hundreds of

hollow microneedles to befabricated on a single patch ofarea, say a square centimeter.

This patch is applied to theskin and drug is delivered tothe body using micropumps.

These micropumps can beelectronically controlled toallow specific amounts of thedrug and also deliver them atspecific intervals.

Microneedles are too small toreach and stimulate the nerveendings, and hence cause nopain to the body.

gtresearchnews.gatech.edu/ newsrelease/NEEDLES.h

http://www.pharmtech.com/pharmtech/data/articlestandard/pharmtech/0
http://gtresearchnews.gatech.edu/newsrelease/NEEDLES.htmlhttp://www.pharmtech.com/pharmtech/data/articlestandard/pharmtech/022004/80733/article.pdfhttp://www.pharmtech.com/pharmtech/data/articlestandard/pharmtech/022004/80733/article.pdfhttp://gtresearchnews.gatech.edu/newsrelease/NEEDLES.html


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Smart Pill A MEMS device that can beimplanted in the human body. Consists of

biosensors

Battery

Control circuitry

Drug reservoirs

The biosensors sense thesubstance to be measured,say insulin.

Once this quantity falls belowa certain amount required bythe body, the pill releases thedrug.

http://mmadou.eng.uci.edu/
http://mmadou.eng.uci.edu/http://mmadou.eng.uci.edu/


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As Detecting Biosensor


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Challenges for MEMS medical

sensorsBiocompatibility remains the biggest hurdle

for MEMS medical devices.

Life of the device.

Retrieving data out of the device.

Resist drifting along with the body fluids.

Summary and


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Summary andConclusionsSelective, field portable sensors have been

demonstrated with rapid sub ppb

Wide dynamic ranges and good selectivity fortarget analytes analytes

Field portable system demonstrated

FET and CV modes of operation

FET gives total change in gate potential, e.g. allactinides actinides.

CV differentiates species based on redoxpotential

More optimization and characterization is needed


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THANK U

Documents

By Mr. Saradindu Ghosh