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Learn about microtechnology
MEMS involves devices having sizes between 1µm and 1mm, combining both electrical and mechanical components on a small chip to achieve certain engineering functions.
THE TERM used for microtechnology is MEMS, short for Micro Electro Mechanical Systems. MEMS emerged about two decades ago and since then it has been identified as one of the most promising technologies. It has the potential to change both industrial and consumer products by combining silicon-based microelectronics with a potential worldwide market in billions of dollars (about $100 billion by 2010).MEMS is a multi-disciplinary field that has devices of sizes less than 1µm to 1mm, combining both electrical and mechanical components on a small chip to achieve certain engineering functions. MEMS devices are usually built using fabrication technologies borrowed from microelectronics. However, these two fields are different from each other. The differences are: (i) Microelectronics or Integrated Circuits (ICs) perform only specific electrical functions whereas MEMS devices can perform a great variety of specific functions; (ii) microelectronic devices have stationary structures whereas MEMS devices may involve moving parts, such as microvalves, pumps and gears. The Karlsruhe Nuclear Research Centre, Karlsruhe, Germany, has produced microgears and micromotors smaller than the size of an ant’s head. The microturbines (150µm in size) used to generate power with a maximum rotational speed of 150,000 revolutions per minute (rpm) and a life span of up to 100 million (1 million = 106rpm) rotations have also been fabricated using MEMS.
The key application area of MEMS technology is the automotive industry where different MEMS-based sensors and actuators are used to make automobiles safer and more comfortable. The other commercial application areas for MEMS are biomedicine, genetic engineering, telecommunications and various other consumer products. The application of MEMS in biomedicine has emerged at such an astounding pace that now, it has its own field — BioMEMS — which includes microrobots for carrying microsurgical tools to the areas in the body where human hands cannot reach during surgery. Then, there is the development of micropumps for controlled delivery and monitoring of minute amounts of medication, DeoxyriboNucleic Acid (DNA) testing and development of artificial pancreas. The major projects involving MEMS in the aerospace industry are microsatellites, microscopes and communications and radar microsystems with reduced weight, size and power requirements, but higher
efficiency. MEMS in consumer products involve bicycle computers, smart toys, smart clothing with the integration of MEMS sensors to provide heat to the body, depending upon the temperature of the environment, sport shoes with automatic cushioning control and scuba diving watches and computers.
MEMS has witnessed an explosive growth during the last decade. Several new jobs and research journals are dedicated to this technology. In fact, this field is so multi-disciplinary that people with different backgrounds can pursue a career in it. For example, students with a natural science background in electrochemistry, molecular biology and plasma physics can pursue their careers in MEMS fabrication technology, whereas students of quantum and molecular physics can enter the field of modeling certain physical behaviour of materials on microscales. Besides natural sciences, five engineering disciplines are also involved in the design, manufacturing and packaging of microsystems, which involve the principles of mechanical engineering. The electric power supply, signal processing circuitry and the functional control of MEMS involve electrical engineering. Chemical engineering is also an essential component in the process of microfabrication of microsystems. Material engineering can be used for the selection of different materials amenable to microfabrication, whereas industrial engineers can pursue a career in the production and assembly of MEMS devices.
Currently, Pakistan does not have a research facility for MEMS. However, the Higher Education Commission (HEC), at the meeting of its departmental development working party (DDWP), held in October of 2003, approved the establishment of a MEMS centre at the NED University of Engineering and Technology, Karachi.
This project will cost Rs35 million and will provide modern laboratory equipment, instruments, semi-conductor processing and micromachining facilities to conduct research at both undergraduate and postgraduate levels. This centre, if completed, will be the best opportunity for students, researchers and professors to invest their efforts in MEMS and bridge the technological gap between Pakistan and the developed countries of the world.
The writer mi_ghauri@yahoo.com is a PhD scholar at the University of Arkansas
Grand in purpose
MEMS technology sounds confusing, because it has yet to make its presence felt in Pakistan. However, it has been around in developed countries for a while and a number of experts have actively propagated its incorporation into mainstream technology. In this regard, Sci-tech World presents excerpts of an invited talk, “Grand in purpose, insignificant in size,” given by William Trimmer at the 10th annual international workshop on “Micro Electro Mechanical Systems” in Nagoya, Japan:
“Perhaps things normally start small, and grow. Man’s habitats have grown from houses, to buildings, to skyscrapers. Our ability to travel has increased from a few miles on foot, to horses, to trains, and now we can encircle the world in a few days... We are enthralled with the big and significant and substantial.
“The insignificant, insubstantial, and minuscule is usually beneath our concern.
“A dozen years ago, I was trying to persuade a machinist to build a very small structure. He listened patiently for a while, and then said, ‘Why do you want something small, a toy? I can make you something that is big and good.’ In his mind, most people’s mind, small things were cheap, and no more than a toy. When H.A. Rowland (professor of physics at the Johns Hopkins University) went to make very small and accurate grooves for diffraction gratings, he used large machines, and buried them in even larger vaults for thermal stability... There is something special about this field of small mechanical systems.
“Most advances represent a specific technology. The Scanning Tunneling Microscope, for example, gives us the ability to detect and perhaps manipulate atoms. High temperature superconductors hold the promise of efficient power transmission, and novel electronic circuits...
“Complex calculations and decisions have now become inexpensive. It is now the mechanical devices needed to interface electronics to the world that are expensive…
“The race to more clever ways to machine micro-parts has just begun. The earlier disdain for the small and insignificant is gone. Now I sense a growing excitement about the micro. Enough people now recognize the importance of micro science… . Things insignificant in size do have a grand purpose.”
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