MEMS APPLICATIONS IN MEDICAL TECHNOLOGY

BYSATYANARAYANA TAMMANA

Role of MEMS and nanotechnology in medical technologies

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First of all, what is MEMS ?

• MEMS stands for Micro Electro Mechanical Systems. • It is a technique of combining Electrical and Mechanical components

together on a chip, to produce a system of miniature dimensions ..

• By miniature, we mean dimensions less than the thickness of human hair !!!!

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Benefits of MEMS and nanotechnology 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 these devices.• Silicon, used in most MEMS devices, interferes lesser with body tissues.

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Can MEMS devices really replace the existing medical devices ?

• A lot of MEMS medical devices have been developed that are much more sensitive and robust than their conventional counterparts.

• Market trends for MEMS medical devices show a promising future ahead.

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

www.edmond-wheelchair.com/ bp_monitors3.htm

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MEMS and endoscopy• What is endoscopy ?• A diagnostic procedure which involves the introduction of a flexible device into

the lower or upper gastrointestinal tract for diagnostic or therapeutic purposes.

• Conventional endoscopes • Can be used to view only the first third of the small intestine.• Require sedation of patient• Is an uncomfortable procedure

http://www.surgical-optics.com/new_autoclavable_rigid_endoscope.htm

http://www.mobileinstrument.com

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MEMS redefines endoscopy with “Lab on a Pill”

Size : 35mmComponents of lab on a pill • Digital camera (CMOS Technology)• Light source• Battery• Radio transmitter• Sensors (MEMS Technology)

Requires no sedation Can show a view of the

entire small intestine Can aid in early detection

of colon cancer

http://www.spie.org/web/oer/august/aug00/cover2.html

Shekhar Bhansali bhansali@eng.usf.edu

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Working of this magic pill !

• The pill is intended to be swallowed like any normal pill.• Once within the body, the pill's sensors sample body fluids and

pick up "meaningful patient data" such as temperature, dissolved oxygen levels and pH.

• The pill is expected to retrieve all data over a 12-hour period and disposed off, once excreted.

• This data is transmitted wirelessly to a card attached to the wrist of the individual.

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Micro-surgical tools

• Present day surgeons operate within a domain restricted by the mobility and control of the surgical tools at hand.

• MEMS surgical tools provide the flexibility and accuracy to perform precision surgery.

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MEMS driven scalpels

• Precise control of the scalpel is an important requirement in any surgery.

• MEMS piezoelectric motor help to accurately position the scalpel.

• MEMS pressure sensors incorporated on the scalpel, can help to measure the force exerted on the area operated upon. Accordingly, the scalpel can he handled.

http://www.ee.ucla.edu/~jjudy/publications/conference/msc_2000_judy.pdf

Shekhar Bhansali bhansali@eng.usf.edu

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Ultrasonic MEMS cutting tool

• These tools make use of piezoelectric materials attached to the cutter.• Consist of microchannels to flush out the fluid and debris while

cutting.• Can be used to cut tough tissues, like the hardened lenses of

patients with cataract

http://www.ee.ucla.edu/~jjudy/publications/conference/msc_2000_judy.pdf

Shekhar Bhansali bhansali@eng.usf.edu

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Skin Resurfacing• Skin resurfacing is a form of cosmetic surgery that is often

used to aesthetically enhance the appearance of wrinkles, skin lesions, pigmentation irregularities, moles, roughness, and scars.

Conventional resurfacing techniques involve the use of :• Dermabraders – devices or tools used in plastic surgery.• Chemical peels – chemicals such as glycolic acid.

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MEMS skin resurfacing tools

• Though still not commercially available, MEMS tools have been found to overcome many drawbacks present in the conventional techniques.

• They can be used to remove raised skin lesions as well as lesions upto certain depths.

• These MEMS structures are packaged onto rotary elements and used over the affected areas.

• The debris can then be sucked outusing a suction pump.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12787986&dopt=Abstract

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Micro/Nano Robots in medical field

• These are micro/nano scale devices capable of treating and eliminating medical problems.

• Such problems may arise due to the accumulation of unwanted organic substances, which interfere with the normal body functions, such as :– Tumors– Life threatening blood clots – Accumulation of scar tissue– Arterial blockage– Localized sites of infection.

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MEMS and drug delivery

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MEMS microneedles

• MEMS enables hundreds of hollow microneedles to be fabricated on a single patch of area, say a square centimeter.

• This patch is applied to the skin and drug is delivered to the body using micropumps.

• These micropumps can be electronically controlled to allow specific amounts of the drug and also deliver them at specific intervals.

• Microneedles are too small to reach and stimulate the nerve endings, and hence cause no pain to the body.

gtresearchnews.gatech.edu/ newsrelease/NEEDLES.htm

http://www.pharmtech.com/pharmtech/data/articlestandard/pharmtech/022004/80733/article.pdf

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Smart Pill

• A MEMS device that can be implanted in the human body.

• Consists of – biosensors – Battery– Control circuitry– Drug reservoirs

• The biosensors sense the substance to be measured, say insulin.

• Once this quantity falls below a certain amount required by the body, the pill releases the drug.

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

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Challenges for MEMS medical sensors

• Biocompatibility 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.

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