MEMS in

biomedical applications

U.GAYATHRI,

Dept of EEE,

Surya group of institutions,

Villupuram.

ABSTRACT:Micromachining and MEMStechnologies can be used to produce complexelectrical, mechanical, fluidic, thermal, optical

,and magnetic structures, devices, and systemson a scale ranging from organs to subcellularorganelles. This miniaturization ability hasenabled MEMS to be applied in many areas ofbiology, medicine, and biomedical engineering a field generally referred to as BioMEMS.

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 !!!!

Benefits of MEMS 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.

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

Classification of biological MEMS devices Biomedical 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 biological samples obtained from the host body.

→ Diagnostics

→ gene sequencing

→ Drug discover

→ pathogen detection

MEMS Sensors

MEMS sensors in the biomedical field maybe used

as:

Critical sensors, used during operations.

Long term sensors for prosthetic devices.

Sensor arrays for rapid monitoring and

diagnosis at home.

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

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.see.ed.ac.uk/~tbt/norchip2002.pdf

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

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

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.

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 up to certain depths.

These MEMS structures are packaged

onto rotary elements and used

over the affected areas.

The debris can then be sucked out

using a suction pump.

Removal of the diseased area

Fatty material deposited on the arterial walls causing artery blockage, can be physically removed using nanoblades.

Physically shredding tumor can pose a great threat. The pieces can be carried to other locations and result in furthering of cancerous cells.

One effective approach to kill the cancerous cells would be to enclose the entire tumor in a nano box and destroying everything in the box. www.foresight.org/.../Gallery/ Captions/Image201.html

A Graphical Representation of Nano robots working in a blood vessel, to remove a cancerous cells using MEMS.

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

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/

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.

REFERENCES:

1. WCB/McGaw-Hill, 1998, ISBN

0-07-290722-[1] Micromechanics and MEMS: Classic and

Seminal Papers to 1990, W. Trimmer (Ed.),

IEEE Press, New York, NY, 1996, ISBN

0-7803-1085-3.

[2] G. T. A. Kovacs, MicromachinedTransducers

Sourcebook3.

[3] M. Madou, Fundamentals of Microfabrication.

Boca Raton, FL: CRC Press, Inc., 1997, ISBN

0-8493-9451-1.

[4] J. Bustillo, R. T. Howe, and R. S. Muller,

“Surface micromachining for microelectromechanical

systems”, Proceedings of the IEEE,

vol. 86, no. 8, August 1998, pp. 1552-1574.

[5] K. E. Petersen, “Silicon as a Mechanical

Material”, Proceedings of the IEEE, vol. 70,

no. 5, May 1982, pp. 420-457.