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MEMS IN MEDICINE

Presented by:1)Vinay. s

[email protected] no:9743040564

2) Shreyas [email protected] no:9738478890

Registration Id:WIZ-117

DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING

UNIVERSITY B.D.T.COLLEGE OF ENGINEERING, DAVANGERE.


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ABST

ACT

MEMS or Micro-Elec ro-Mech ic l Systems arechips that are made i semiconductor fabs that combine

electronic functions and mechanical actions. MEMS

devices can sense and control making them valuable

for numerous applications that include ink jet printers,

automotive motion sensors and even digital projectors.

But MEMS can also be used in the medical field tomeasure blood pressure within the body and detect ions.MEMS analyzers can be used to perform biological tests

and even sequence DNA. This paper will describe the

rapidly emerging field of BioMEMS and discuss presentand future applications.

Keywords: BioMEMS, medicine

BACKG

OUND

Remarkable advancement in medicine are increasingl accomplished through the innovative application ofelectronics, photonics, and related advanced technologies.

Longer range preventive medicine and very earlypre-emptive intervention are becoming essential strategies tomore cost-effective health maintenance made practicalthrough continuing advances in diagnostics and wellnessassessment enabled by leading-edge technology from other

fields. Early medicine emphasi ed external examination ofthe patient. Later, breakthroughs such as x-ray permittedinternal examination from the outside. Electronic andphotonic advancements have enhanced these diagnostictechniques, but new devices and extreme miniaturi ationnow permit examination, sensing, and monitoring frominside the patient. Concurrent breakthroughs in molecularbiology and better understanding of coding and functions ofDNA, is building up knowledge that will make diagnostics

even more powerful and allow deployment of preventiveand interceptive medicaltechniques much earlier for greatersuccess. Molecular based medicine is the ultimate frontier.Today, MEMS devices, electromechanical chip technology,is steadily being adopted and adapted by the biomedicalfield to bring the significant benefits of micromechanics.

MEMS, or Micro-Electro-Mechanical Systems, are tinychips that can be produced by semiconductor processes tocombine mechanical sensing, control and motion to solidstate electronics to deliver extraordinary functionality andversatility. Essentially all of the mechanical and

Electromechanical machines from the macro-world can nowbe crafted into a tiny chip that can enterthe micro-world andinteract with life systems. MEMS can sense pressure, detect

motion, measure forces, identify bio-agents, pump andcontrol fluids, and perform other actions that have greatvalue to the medical and biological fields. BioMEMS is theterm used to describe the chips designed specifically forthese applications. These BioMEMS chips can serve aschemical and biological analysers, micro-pumps andcontrollers, hearing aid components and many moreapplications that will be discussed. But in the future,BioMEMS medical practitioners could become permanentinhabitants ofthe body.

What is MEMS?

MEMS, Micro-Electro-Mechanical Systems, is theultimate enabling technology forthe integration of anyPhysical, chemical and biological phenomena that include

Motion, light, sound, chemistry, biochemistry, radio wavesand computation, but all on a single chip. These chips canmimic all of our senses and thus eventually be used asbody replacements or enhancements heralding a new age ofbionics. While simpler systems, such as hearing aids, havebeen implemented, extraordinary bio-systems will emerge inthe future. MEMS will add the eyes, noise, ears, tactile feel,and other sensory input while the on-chip electronic logicfunction will serve as the brain to condition signals,organi es data, control, analyze and integrate input andoutput. The merging of motion, sensing and computationrepresents a significant new levelin technology.

MEMS devices can possess high-level integration fornumerous categories of functions. This unification offunctionality encompasses high precision micro-mechanicalmotion, optics, and micro-fluidics, living cell interaction,sound, radio waves and much more. Senses could evenbe enhanced making it possible to even see in the darkor extend the hearing range. The additional features ofcomputation and centralized control of all actions into a

fully integrated system could deliver surprisingly versatilenew products. MEMS is also abouttechnology convergencewhere miniature devices including gears, propellers,turbines, pumps, mirrors, motors, radio elements, radiationsensors, and many types of detectors and other assemblagesare synergistically united in a new micro- and even a nano-


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World. A key attribute is that MEMS can combine andintegrate complete systems, from a library of parts thatinclude micron-sized motors, tweezers, pumps, separators,injectors, needles, and scalpels. MEMS places systemstogether on a fully integrated and self-contained single pieceof silicon, or other construction material, that previouslycould only exist in the macro world. It is remarkable thatthese previously isolated technologies are now convergingonto a tiny single chip of silicon.

BioMEMS devices, however, will become the mostimportant class in the future. They can already detectspecific ions and molecules, sense pressure within an artery,and even help detect defective DNA. MEMS adds the eyes,nose,earsand some senses that humans dont even possess,but merges mechanics with the electronic brain ofsemiconductorlogic on a single chip. MEMS can also exertcontrol using untiring electrically-powered muscles tomove and manipulate or pump fluids and dispense drugs.The merging of motion, sensing and computation mostcertainly represents the most advanced level in technologythat is still embryonic. While much of traditionalcommoditized electronics is leaving our shores, the

growing in America.

How MEMS works

MEMS chips can be mass produced using modifiedsemiconductor processes. Silicon is the most commonmaterial and allows transistors and integrated circuits to beformed on the same chip as the mechanical parts. MEMSfabrication involves forming sacrificial and permanentregions within the substrate by processes common tosemiconductor manufacturing. Final removal, or releaseof sacrificial material that can be silicon dioxide (SiO

creates the 3D permanent structure that can have movingparts including levers, hinges, gears, and evensprocket/drive chain assemblies. Mechanical motion isproduced by actuators that are fabricated during thestructure-building processes. Actuators include classeswhere movement is produced by electrostatic, magnetic,thermal action, and other less common means. Somesource is typically electricity that can be converted tothermal, photonic, or mechanical energy. This ability toproduce controlled motion from energy input can providemicroscopic pumps, tweezers, abraders, heaters, injectors,reactors, and almost any machine that can be imagined. But

electro-mechanics also produces extremely small andsensitive devices for detecting and measuring, motion,acceleration, pressure, weak electrical signals, ions, andspecific biological agents all useful for medical applications.

Types of BioMEMS Devices

We can divide BioMEMS into several categories. Thesimplest demarcation is to look atthe basic operation ofthechip. The BioMEMS device may be designed for sensingthat can include measuring, monitoring and detecting insidethe body or atthe surface. Sensing is the largest category inthe non-medical MEMS sector and the same probably holdstrue for medical. The remaining devices can probably beclassified as action type devices whose primary function

is to act upon the body, its materials such as fluids, or uponexternal agents, especially drugs to be administered. Thereare some cross-over areas where a single chip fits bothcategories such as a device that monitors glucose levels andadministers insulin butthis type is not very common atthis

early stage of BioMEMS. We can next subdivide thesensors and action categories by function, such aspressure sensor, and then add another subdivision of thefunction by specific application. Using this approach, aBioMEMS chip inserted into an artery might be classified assensor, pressure, blood, for example. Table 1 classifiesBioMEMS devices.

Table 1

1.1. Pressure1.2. Temperature1.3. Glucose1.4. DNA factors1.5. Force

1.5.1. Muscular1.5.2. Organ1.5.3. Tissue tension

1.6. Electricalimpulse1.6.1. Nerve

1.6.2. Brain

1.6.3. Heart1.7. Gas detectors

1.7.1. Oxygen

1.7.2. Carbon dioxide

1.9. Chemicalion

2. ACTION DEVICES

2.1. Microfluidic Pumps2.1.1. Circulatory2.1.2. Drug delivery

2.2. Fluid filters2.3. Separators2.4. Transdermalinterface

2.5. DNA amplification/analysis[Many more can be added]


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BIOMEMS MEDICAL APPLICATIONS

This section describes products that have beendeveloped,those that are in the lab, and some that are beingproposed. The MEMS-assisted medical area is relativelynew, butthere is substantial workin progress at universities,governmentlaboratories, hospitals and private industry. Theterm BioMEMS will trigger at least 40,000 hits in anInternet search. We are only at the beginning of this

remarkable area of medicine that already has somesuccesses, but holds immeasurable promise for the future.While much work is underway, the inevitable and well-known long pathway from lab to patient use extends thetimeline more so than any other field. The newness andstrangeness of MEMS will likely make regulatory approvaleven more challenging. Science fiction writers have madematters worse by creating MEMS and Nanotech phobias.The next section will describe some ofthe more interestingBioMEMS applications that have been reported.`

Sensors; Blood Pressure

MEMS pressure sensors have been developed andcommercialized outside of the medical field and representone of the largest classes of commercial MEMS products.Their primary use is in the automotive industry where thepressure of fluids and gases must be measured and oftenmonitored. Car air conditioners, for example, may use 2 or 3pressure sensors for safety and optimum performance.While environments are completely different, there aresimilarities between the human body and a vehicle in termsof circulating fluids and critical pressures so itis no wonderthat BioMEMS pressure sensors are an important category.The human circulatory system not only generates pressurewithin, it has a complex and constantly varying value by thevery nature of the heart pump and changes that constantlyoccur in human plumbing. When we add extrememiniaturization and biocompatibility to this already complexsystem, the BioMEMS challenge is much largerthan for any

other MEMS area.

Integrated Sensing Systems Inc., or ISSYS, performed

studies on their own BioMEMS wireless, battery less,

implantable pressure sensor as described by Nader Najafi,

Ph.D., president and CEO. Animal studies showed the

accuracy and proved the functional feasibility of BioMEMS

technology for biological sensing. The results were very

encouraging and exceeded the requirements, including high

sampling speed and resolution. A second generation of

wireless sensors is being developed to provide a total

system solution.

The company presently offers the two sensors shown inFigure 1 for medical applications and claims to have very

High biocompatibility and corrosion resistance. Figure 2shows the very small feature size ofthe companys pressure

sensors that are designed for medical applications. ISSYS isdeveloping intelligent BioMEMS sensors and systems toenhance the quality of medicaltreatmentthat can apply to:

Measure pressure gradients across heart valvesaccurately to help assess valve disease

Diagnose and monitor congestive heart failure Measure cardiac output and compliance

Monitorintracranial pressures in hydrocephaluspatients


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Understand glaucoma diseaseprogression and improve patient care

Improve gastrointestinal tract diagnosticcapabilities to help treat gastro esophagealreflux disease (GER )

Assist in diagnosis of urological disorders

Measure drug delivery rate for infusionsystems

ISSYS also provides MEMS design and fabrication

services as well as technical expertise in this area with

a focus on biological and medical applications.

The Cleveland Clini Foundation BioMEMSLaboratory is developing systems to biomedicalapplications since BioMEMS will bring smaller, moreaccurate, less invasive and more cost-effectivebiomedical devices. A miniature implantable, wirelessBioMEMS pressure sensor is able to

monitor physiological measurements, such as

abdominal, aortic aneurysm pressure, and intraocular,intracranial and intervertebral pressures. ThisBioMEMS Laboratory, which occupies space in theLernerResearch Institute, is a state-of- the-art facilityoptimized for BioMEMS research and development.This laboratory is e uipped

with extensive hardware and software tools for the design,packaging, and characterization of biomedical

microsystems. BioMEMS devices and a speciallyinstrumented probe station are available for microactuator characterization, micro-sensor testing andcalibration, and testing of micro fluidic devices toaccommodate the uni ue testing re uirements. Softwarepackages are used for the layout and performancemodelling ofBioMEMS device designs.

Am lifi ation/Analysis/Sequen ingMetriGenix started working with Infineon several

years ago to develop BioMEMS chips that use DNAchemistry that is more efficient and faster than existingtechnology. Today's DNA analysis chips use tiny,shallow wells to contain the DNA and reagents. TheMetriGenix design uses a capillary flow-through

techni ue whose prime advantage is to speed up thereactions. Infineon has now embarked on otherBioMEMSdevelopment projects such as an electronic cell- culturesystem that gives biological researchers the ability togrow neurons on an electronic substrate and record theirelectronic behaviour.

Minimizing the sample size to use only microlitersenables the system to run a battery of tests with timesavings significant. Se uencing a sample of DNA toapproximately

600 bases using the classic slab gel method takes about 4to

6 hours. The BioMEMS method using a capillarysystem


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Provides results with the same accuracy and precision inabout 2 or 3 hours. In the future, they expect to get the sameaccuracy and precision in 20 to 30 minutes with anoptimized version.

STMICROELECTRONICS is also active in BioMEMS theirprototype lab-on-a-chip is very compact, making itsuitable for point-of-care applications. This large anddiversified semiconductor company is intensifying its

involvement in medical BioMEMS and is seeking partnersto market its lab-on-a-chip products. ST has producedMEMS for autos and industry for many years, but this newproduct is its first venture into BioMEMS. They haveinvested in state-of-the-art research facilities to build up theBioMEMS product lines rather than use retired fabs as someothers have done. Their silicon lab-on-a-chip will becomevery economical through large volume production using the

companys massive multi-billion dollar semiconductor fabs.This gives the BioMEMS products the production benefitsusually only found in the huge clean rooms ofsemiconductor manufacturing of standard electronics.Instead of the small volumes produced by workshop -stylestart-up companies, BioMEMS will become part of a

giant production line. Their strategy is to select productsthat are marketed through selected partners who have goodcontrol over their end markets. The high volume capacity ofST can bring the niche BioMEMS market into one of high-volume productivity, lower costs and constant marketpressure on prices.

Lab-on-a-chip allows small amounts of bodily fluids to betested in seconds. All chemical

Reactions occur inside the biochips buried channels or onits surface. And because the cartridge that carries the chip isself-contained and disposable, the system strongly reduces

The cross-contamination risks of conventional multi-step Protocols. The ST prototype is designed to handlemicro fluidics and some of the knowledge is basedon

Expertise in MEMS inkjet printer chips. The prototypeintegrates two fundamental steps of genetic analysis:amplification and detection. This microscale approachresults in time and cost savings. Blood samples typically donot contain enough DNA for analysis and must be amplified,or copied, many times to increase sample size. This is donethrough a process called polymerase chain reaction (PCR), atechni ue for replicating, or cloning DNA. BioMEMS PCRamplification can be performed in 15 minutes, a process that

might ordinarily take 1 or 2 days.

A researcher mixes a DNA sample with a polymerasenzyme and DNA primers and passes it through a bank of12 microscopic channels, each measuring 150-200microns,within the silicon.Electrical heating elements that

are embedded resistors in the silicon, heat the channels,and the electronics cycles the mixture through threeprecisely predetermined temperature profiles toamplify the DNA sample. The system then pumps theamplified DNA into the biochips detection area usingmicrofluidics. The detector contains DNA fragmentsattached to the surface probe. Inside the probe, matchingDNA fragments within the sample attach themselves to the

fragments on the electrodes while the DNA fragmentswithout matching patterns fall away. The system achievesaccuracy by temperature control and detects the DNAfragments by illuminating them with a laser and observingwhich electrodes fluoresce.

This approach also reduces the size of thee uipment because the external circuitry driving the chip isvery compact (20 cm x 20 cm x 20 cm box) making itsuitable for point-of-care applications. DNA analysis chipsare used to diagnose genetic diseases, perform drugdiscovery, test livestock and monitor water supplies. TheST chip is unusual in that it is based on silicon, ratherthan on the plastic and glass substrate normally used forDNA detection. The benefit of the silicon approach is that itwill allow much greater levels of integration and bothamplification and detection are performed for complete

sample-to-result analysis.IBM is another big participant in BioMEMS and one of theearliest commercial entrants. Their DNA BioMEMS chip


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operates on a totally different principle that shows the greatversatility of this field. A MEMS chip is produced withvery thin silicon cantilevered beams radiating outward onall four fre uency and any DNA adsorption reduces thisvibration and it can be interpreted uantitatively. Eachbeam is coated with a bio-agent that can be DNA or othermaterial that will selectively interact with the sampleunder test. Absorption by specific beams is detected by thechip and interpreted by the system. Each of the 250 silicon

beams can be used to detect a different bio-agent. Seefigure below.

Genome Sequen ingResearchers at Whitehead Institute are testing a newMEMS-based gene se uencing system. Their BioMEMS768 Se uencer can se uence the entire human genome inonly one year, processing up to 7 million DNA letters aday, and that is about seven times faster than anything inuse. Scientists began working on the project in 1999 with aNational Human Genome Research Institute grant. Thetechnology eventually will help scientists uickly determinethe exact genetic se uence of the DNA of many differentorganisms, and could lead to faster forensic analysis of

DNA gathered in criminal cases.

The core of the BioMEMS machine is a large chip etchedwith tiny microchannels or lanes. The number in the nameis derived from the fact that it tests half, or 384 lanes ofDNA at a time. Each lane can accommodate progressivelylonger strands of DNA: about 850 bases (the nucleic acidsfound in DNA, abbreviated by the letters A, C, T or G),compared to the current 550 bases per lane. It takes about 45minutes to read the DNA from one of the BioMEMS 768lanes. The machine has two chips; one is prepared as theother is se uenced, so that the machine is running at alltimes. Savings come from low maintenance, speed andusing smaller amounts of reagents. The BioMEMS system

uses a DNA loading process that will eventually need only 1percent as much DNA sample.

Other efforts to develop BioMEMS devices for clinicaldiagnostics have led to commercializing several related, butdifferent, technologies used in massively high-throughputgenomic screening assays. One of these lab-on-a-chipplatforms is the Lab Chip product by Calliper Life Sciences(Hopkinton, MA) and the Gene Chip micro-array system byAffymetrix (Santa Clara, CA). Both systems offer theadvantages of performing assays in micro fluidicenvironments and reduce reagent usage, have faster assay

times, and can have the ability to perform reactions that areimpossible in the macro world.

Commercial BioMEMS-based platforms have disposablecartridges and the lab-on-a-chip devices can handle

microfiber, nanoliter, or even peculator volumes. Systemscontain a network of interconnected individual buildingblocks. The ability to design, test, and fabricate thesebuilding blocks that includes fluidic valves, channels,pumps, and mixers that can process larger sample volumes,is crucial to developing BioMEMS devices. One importantdesign element for BioMEMS platforms is that they mustinclude totally automated sample preparation of raw patientsamples. This type of sample preparation has been lacking

in lab-on-a-chip devices andTarget purification, extraction,capture, and volume reductionhave been handled off chip. IfThe manufacturer decides toInclude sample processing in thesupporting instrument, then theinstrument must remain compactamenable to point-of-caresettings. Size of a complete unitis still a challenge that willre uire almost all devices to bemicro- or even nano-scale.

The Micro Total Analysis System (-TAS) is a BioMEMS-based concept being developed at the Technical Universityof Denmark (DTU) North of Copenhagen in the city ofLyngby. The -TAS can perform functions on reagents andsamples such as transportation, extraction, purification,mixing, separation, chromatography, and detection. It canbring innovation to the chemical and environmental areas,but especially the biomedical field. Micro concave grating is

used for the wave division demultiplexing of fibercommunication with 81 channels. This optical micro-concave-grating was fabricated with advanced MEMSsilicon etching techni ues. This is a long-term project.

MEMS AUGME

TATION

Hearing AidsStarkey Labs is using the Nanotech Chip for hearing aidsfrom NVE, all located in MN. The chip uses a GMRsensor


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to detect the use of telephones and to adjust the hearing aidaccordingly. The sensors are based on a chip that useselectron spin rather than charge to store information and canbe classified as Nanoelectronic devices. The automaticswitching frees a wearer of any need to switch manually.The sensor, one-third the size of the switch's coil, is builtfrom nanoscale layers of magnetic thin films just a fewatomic layers thick. Tiny MEMS microphones are also now

commercially available from several companies that can beused in hearing aids.

We can expect to see hearing implants in the future,however. A MEMS-based ear implant has been designed bythe University of Michigan and looks like a cochlea. Thisappears to be the first hearing chip with integratedelectronics and it uses micro machined cantilevered

beams for sound interpretation. Beams of different lengthsare used to distinguish fre uencies. A piezoelectric vibratorwill interact with the ear. A commercial version is still yearsaway.

Sig t Aids

MEMS Based Retinal Implants research is being carried outby several laboratories including Sandia NationalLaboratories in conjunction with other DOE National

Laboratories, the Doheny Eye Institute and Second SightCorp. They are developing technologies to enable aconforming high-density electrode array for use in animplantable artificial retina. The project goal is to providesome level of useful vision to patients with diseases likemacular degeneration and retinitis pigmentosa. There arecurrently several implant designs being developed in the USand abroad but there are significant challenging design

problems as would be expected. Currently, Second-Sightand The Doheny Eye Institute are performing clinicalstudies with a low-resolution implant of their own design.BioMEMS offers features that are beneficial to an artificial

implant and are truly uni ue to this technology. The presentdevelopment effort will use external and internal devices asshown in the diagram.

KidneyCan MEMS kidney chips be fabricated? The kidney is the

number one organ needed for replacement with 35,000

Americans re

uiring kidney dialysis at a cost of $25 billionper year. There are 15,000 kidney transplants in the UnitedStates every year but there are 58,000 waiting. But shouldthe artificial kidney be organic, an inorganic structure, orbiological hybrid? Semiconductor processes using MEMStechni ues can now make 3D structures so why not make amicro-filter or perhaps even a nano-filter. The artificial kidneysystem could end up being an entire wafer or an array ofchips to meet the capacity needs.

Most of the developers think that for now, that the artificialkidney needs to be outside of the body, but in the future, it willbe a transplant inside. The artificial device faces a challengesince the kidney filters 180 liters per day of blood. Draper

Labs has a long history of MEMS development includingfluidics. They are doing filter scale-up using microfluidicdevices. Each layer has a micro-channel etched into a chip andscale-up just involves adding more layers using MEMSfabrication techni ues. Massachusetts General Hospital isalso doing work headed by Joseph P. Vacanti. He is usingpattern silicon wafers as the master mold and making copiesfrom plastic. The next step is to grow real cells on the plastic.The ultimate goal is a fully organic kidney, but an inorganicpump and filter system could be an interim step. Work is alsogoing on at Brown University in Providence, Rhode Island byMichael J. Lysaght who is the director for the center ofbiomedical engineering.

The Heart

CardioMEMS, a member of Georgia Techs AdvancedTechnology Development Center (ATDC), is pioneering aBioMEMS sensor to monitor heart patients. They havecombined wireless technology with BioMEMS to providedoctors with more information while making testing less


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invasive for patients. The FDA approved the unit underinvestigational device exemption (IDE) to enable thecompany to begin clinical trials in the United States for itsEndoSensor. The EndoSensor measures blood pressure inpeople who have an abdominal aortic aneurysm, aweakening in the lower aorta. This condition ranks as the13th leading cause of death in the United States. If theaneurysm ruptures, a person can bleed to death withinminutes.

Doctors can treat an aneurysm with a stent graft, a slenderfabric tube placed inside the bulging artery to brace it andrelieve pressure by creating a channel for blood flow. Still,the stent can fail, resulting in leakage of blood into theaneurysm, which can cause the aneurysm to burst. For thisreason, lifetime monitoring is re uired. The photo shows theEndoSensor that can be implanted to measure pressure in ananeurism being treated by a stent graft.

CardioMEMS biocompatible sensor implanted along withthe stent, monitors the stent more effectively than CT scans.

Its also cheaper and more convenient. During checkups,patients dont even need to remove cloths. The physicianmerely waves an electronic wand in front of the patientschest. Radio-fre uency waves activate the EndoSensor,which takes pressure measurements and then relays theinformation to an external receiver and monitor.Approximately 100 patients in four countries (the UnitedStates, Canada, Argentina and Brazil) have receivedsensors. Data will be submitted from the trials to the FDAand the EndoSensor could start selling in mid-2005.

CardioMEMS has also been advancing its HeartSensor, awireless device that measures intracardiac pressure inpatients with congestive heart failure. Similar to the

EndoSensor, the HeartSensor is inserted through a catheterin a non-surgical procedure. Patients receive monitoringelectronics to take home which are used to conduct dailypressure readings. Then that data is transferred over a phoneline to their physician. The HeartSensor enables doctors tomonitor patients more closely and adjust medications as

they see the disease progressing. The sensor detects achange in the body before any external symptoms aremanifested and thus serves as an early warning system.Early prototypes were manufactured at Georgia Tech, butCardioMEMS has signed an agreement with an establishedMEMS foundry to produce the EndoSensor. The companyhas already demonstrated the sensors that can be producedin large uantities at an affordable cost. Doctors can monitorthe information from the chip in the office or remotely frompatients' homes as shown in the diagram, bottom left.

Medtronic Inc.'s has developed the BioMEMS-based

CareLink Monitor fordefibrillator patients who canhold a monitor over their bodyto pick up the chip's signals.That information is fed into aPDA or other device and thencalled in to the doctor by thepatient or transmitted via theInternet to the physician over

telephone lines.I

mplant isshown in the photo.

MEMS could also help improve pacemakers anddefibrillators. The basic function of pacemakers hasn'tchanged a lot in 20 years. All pacemakers include acomputer, some memory, and a telemetry link; additionalsensors might provide more information to the user's doctor,such as blood oxygen measurements, pH level, or otherinformation. People with pacemakers tend to be subject toother diseases as well, and a group of implanted sensorscould provide early warnings about the patient's health.Maybe someday they will be implanted in healthy people.

Heart Tissue Produ

tionHow about a new artificial heart? MIT is working in

this area. They have come up with a living bandage concept.They grow heart cells and subject them to poultices ofelectrical current so that they will react like the heart

muscles do. The tissue made of the cells can be crafted uponto the heart where the muscle is weakened. It will beat inrhythm with the heart muscle since the heart sends outelectrical pulses.

CONCLUSIONS AND SUMMARYMEMS in medicine has already made an impact. The

relatively new BioMEMS market was already at $215million in 2001 and is projected to grow at more than 20

percent a year to $550 million in 2006 and finally top $1billion by 2011 according to In-Stat-MDR and others. Thedemand could support a faster growth rate that is typicallydelayed by extensive and lengthy testing and approvalre uirements.


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BioMEMS-based medical devices are now found inemergency rooms, surgical suites, doctors offices, and evenin personal health care devices. So it is quite possible thatmany of us have already been helped by this emergingtechnology. And if you have not yet had the encounter, theincreasing application of BioMEMS in medicine means thatyou will have that experience in the future and it could save

your life. Sensors are an important entry product class thathas been able to leverage non-medical MEMS sensortechnology. Both internal and external sensors, such asblood pressure monitors, are being deployed and enhanced.Lab-on-a-chip for point-of-care diagnostics and life scienceresearch is another very active area. MEMS technology istargeting a number of health care-related applications,

including real-time circulatory system monitoring, glucosetesting, pacemakers and heart monitoring, nerve and musclestimulation and biotechnology analytical systems. Sensoryaids and replacement devices are in testing and rudimentaryvision restoration appears to be close. The most diversifiedand well-suited opportunity for MEMS in medicine willlikely continue to be sensors, however. The next step is

incorporation into surgical instrumentation. Other MEMSdevices, particularly needles, probes and lab-on-a-chip arealso on the verge of very rapid growth. Needles/probescondition monitoring will bring new, novel means of drugdelivery that will become an important category startingwith diabetes treatment but expanding to other drug-treatable diseases as more knowledge is gained.

THE FUTU ! E

BioMEMS combines micro-mechanics, silicon chipsemiconductor electronics, and the basic living molecularprocesses and future results and discoveries will bephenomenal and sometimes unexpected. Visionaries willblend molecular biology with computational systems at the

atomic scale to create bio-nano-electro-mechanical systems(BioNEMS) that could become a major factor innanotechnology. But in the near term, many small biotech

concerns and some major semiconductor makers willcontinue to commercialize products based on BioMEMS. Insome areas, BioMEMS has improved existing medicaltechnologies. But brand new devices never before seen inthe medical sector will be developed.

The BioMEMS impact on medicine and healthcare at themoment may be subtle but is still revolutionary. Use ofBioMEMS technology will enable us to advance medicaldiagnostics and therapies by reducing device size and costwhile increasing capabilities. Future applications include

miniaturized versions of drug delivery systems, transducersfor ultrasound images, and more implanted monitors withtelemetry. Pressure and temperature sensors for minimallyinvasive surgery/follow-up are already here as described

earlier but will be reduced to easily-implantable or wearablesizes. Researchers are investigating magnetic flow cellsorting for various diagnostic and therapeutic applications,such as rapid screening for cancer cells in blood or blood-forming stem-celltransplantation and in model cell systemsof human peripheral lymphocytes, cultured cell lines, and

samples donated by patients, such as bone marrow.BioMEMS capabilities will only increase and diversify inthe future.

Analysis and monitoring will continue to be important areasfor some time. While large and small companies haveadvanced DNA analysis, this is only the first step. There area lot of promising applications for DNA detection andlinking gene deficiencies to disease, drug design, patientmonitoring and many high-growth applications are just a

few. Butthere is a much larger field beyond DNA. The nextstep is proteomics, the study of how proteins are formed andhow they operate. DNA has some mechanical abilities basedon its lock-and-key method of bonding, but proteins are the

physical building blocks and basic mechanical units ofliving organisms.

Although there are tremendous opportunities for BioMEMSin the medical market, major challenges loom ahead. Thetwo biggest hurdles are the requirement of FDA approval aswell as a constrictive supply chain that can be a dauntingbarrier to entry. These are factors that increase delays forthis particular market

Robotic surgery and augmentation is on the horizon wheremicrochips will be placed inside the body, such as on hearttissue for repair or inside of blood vessels for monitoring.The chips could contain cells that can generate specific

types of tissue, such as muscles, organs, blood and others.Chips could also contain chemicals that would stimulate thegrowth of blood vessels, or medication that is slowlyreleased into the body at specific points and under particulardemands. The use of BioMEMS will move heart diseasetreatment to the next level and this has the potential to letphysicians assess the benefit of their work right in theoperating room instead of waiting for symptoms. A surgeoncould also place a slow-release anesthetic in the wound atthe end of the surgical procedure eliminating the need fortraditional post-operation pain relief. A painkiller releasedslowly inside the body would prevent the pain impulsesfrom reaching the brain so a patient would never feel thepain.

Preventive medicine will also be enhanced to enable us todiagnose the earliest abnormalities and plan more suitableand successful strategies. A chip might relay to physiciansinformation on potentially cancerous tissues. BioMEMS


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chips equipped with sensors could detect mutated genes ordangerous levels of hormones, and enable doctors todetermine which tissues to treat long before thesituation goes critical. The day may come when MEMS-enabled micro-robots, or even nanobots, travel throughthe body to clear arteries and make repairs borrowing ascene from the classic 1966 science fiction movieFantastic Voyage. The movie plot used miniaturization

technology to enter the patients body with a guided

fluid-impervious vehicle to clear a blood clot. Althoughthe science fiction plot was based on atomic-levelminiaturization of a macro-world

submarine, the BioMEMS vehicle is plausible in thefuture. These guided, or perhaps self-guided, self-propelled devices could be injected into the body toperform life-saving tasks or go on patrols to look forproblems and do routine body maintenance. MEMS hasalready delivered tweezers, scalpels, injectors, cell-splitters, all kinds of sensors and several kinds ofpropulsion devices including turbines. So in the futureyour doctor may advise to take two MEMS and gets

some rest.

EFE"

ENCES

[ 1] P. L. Fuhr et al. Performance and healthmonitoring ofthe Stafford Medical building

using embedded sensors. Journal of SmartMaterials and Structures 1, pp. 63-68, 1992.

[2] C. Matsumoto, Calient Patches Its Strategy,LightReading, February 14, 2005

(http://www.lightreading.com/document.asp?

site= lightreading&doc_id=68031).

[3] www.webwire.com/ViewPressRel.asp?aId=1617

[4 ] Goldman Sachs and McKinsey & Company, USCommunications Infrastructure at a Crossroads:Opportunities Amid the Gloom, August 2001.


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