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The machines of Lilliput
The integration of mechanical and electronic systems in tiny mass-produced packages is opening up entirely new market niches.
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The microelectronic circuits etched onto the billions of silicon chips produced annually are made up of very fine semiconductor features. In state-of-the-art integrated circuits (ICs), many are narrower than 65 nanometres - a fraction of the wavelength of visible light.
What if the processes making this possible could be used to make mechanical components too? Could microscopic mechanisms be mass produced like ICs? The answer is ‘yes'. In fact, microelectromechanical systems - also called MEMS - are already available for a growing number of applications. In the size spectrum, they are midway between objects still visible to the naked eye and the atomic scale constructs of nanotechnology.
Fabricating micromachines and microelectronic circuits side by side leads to machines with information processing and networking intelligence, capable of sensing, elaborating, communicating, and acting. As with microprocessors and lasers in earlier decades, the novelty is not that these microdevices exist at all, but that they have suddenly become both smarter and cheaper.
Colm McGinley is a specialist in this field at the European Patent Office. He says MEMS are a spin-off of the semiconductor industry: "Process technologies developed for integrated circuits have been applied to mechanical machining technologies." At present, they produce features with sizes in the 0,1 to 100 micrometres range. Most MEMS products are built in microelectronics plants a few generations older than the newest 65-nanometre plants, which are getting too old for state-of-the-art chip production and are easily converted to produce MEMS.
Pressured start, broadening markets
One of these process technologies, ‘bulk micromachining', was adopted by pressure-sensor manufacturers in the early 1970s to improve the performance of piezoresistive pressure sensors. Today, under the pull of the market, MEMS pressure sensors sell in large numbers. Healthcare providers are among the biggest customers, and blood-pressure measurement - especially by disposable MEMS sensors connected to intravenous drips - is one of the most relevant applications.
The automotive industry is another big customer: manifold air pressure, fuel vapour pressure, oil pressure and tyre pressure are all monitored by MEMS sensing devices. A new car today is likely to contain 50 or so MEMS components, in systems for engine management, braking, noise reduction, airbag deployment, rollover detection, and more.
Wicht Technologie Consulting (WTC) coordinates the preparation of the MEMS market reports published by NEXUS (Network of Excellence in Multi-functional Microsystems), a professional association established in 1992 through the European Community to promote R&D of MEMS (1) . Jérémie Bouchaud, head of market research at WTC, sees the automotive industry as a key player in MEMS development.
"The automotive industry is an innovation driver and keeps moving ahead at a very fast pace," he says. "Spending on MEMS by car manufacturers is growing at more than 10% a year, even though it is a well-established market." New safety regulations look set to accelerate the trend. "The electronic stability programme will be mandatory in the USA from 2010." All new cars will have to include MEMS gyroscopes and accelerometers to prevent rollover. At present, stability systems like this are installed in only 20-30% of new cars.
Given the tiny space they occupy, MEMS accelerometers contain remarkably complex structures. Their manufacture has typically involved 'surface micromachining', another key process technology. Through the deposition and selective etching of several thin layers of material, intricate 3D features are possible. In this way, a MEMS design can incorporate pivots, sliding parts, rotors and even gearwheels, all familiar macro-scale mechanical components.
Processes, fertile ground for inventions
MEMS design is still far from being a mature field, especially in the diverse manufacturing processes used worldwide. Process innovation is a fertile source of patent claims for McGinley and his fellow examiners at the EPO. "From the point of view of MEMS with generic applicability, processes of manufacture are very important. They make up at least 50% of our examination work load in this area," he says.
For instance, the ‘Bosch process' has just earned its creators, Bosch's Franz Lärmer and Andrea Urban, the title of European Inventors of the Year 2007 (2) . McGinley rates it highly: "It was a breakthrough. Etching silicon had been limited in terms of the geometrical shape you could achieve with it. The Bosch process is a way of refining the hammer and chisel of micromachining so that you could create precise features with much greater depth than before."
The future of microtechnology
Most of MEMS are still based on silicon. Yet, it has become apparent that the high cost of silicon-based MEMS hinders their future, and retards their entrance into new markets. Potential substitute or supplement materials to silicon are polymers, which are cheaper and available in a great variety.
Interdisciplinary advancements in microtechnology are expected to do for mechanical, optical, and chemical devices what silicon chips have done for information processing. Shrinking chemistry labs, mechanical devices, and optical systems will bring benefits comparable to those brought by microelectronics.
Already, micro-devices for separating DNA quickly and with high efficiency have proved a useful tool in deciphering the human genome. One day soon there might be point-of-care chips able to analyze blood samples in the doctor's office, at the hospital bed or even in the home.
As for industrial chemistry, on the horizon is the ambitious concept of a complete, programmable chemistry laboratory on a chip. Microsystems for handling liquids, involving miniature pumps and valves, are at the heart of such a lab-on-a-chip concept. Micro fluidics is a thriving field, and chip-based microreactors have the potential to change dramatically how and where chemicals are synthesized.
As for mechanics, the heads of ink-jet printers and hard-disk drives are already best selling microsystems, one to produce microscopic jets of ink, the other to adjust mechanically the position of the magnetic sensors that fly above the disk's surface. One of the major challenges is now to develop miniature engines and on-chip power generators.
As for optics, integrating MEMS with radio frequency electronics and photonics is attracting much attention. The interest of the defence industry for microtechnologies is obviously very high, and understandably surrounded by secrecy. The Defence Advanced Research Projects Agency (DARPA), which is the central research and development organisation for the US Department of Defence, lists MEMS as one of their core technologies.
Whether fitted with DNA probes, miniature thermometers, tiny microphones or spectrometers, synthetic noses, location detectors, or motion sensors, microdevices will provide richer and richer information about the physical world. Inevitably, they will change it too.
From the perspective of patenting
If an applicant were to submit a patent claim for a micro-scale device thinking that exceptionally small size alone would make it patentable, he would be disappointed. Making a smaller analogue of a known macro-scale device -possibly sufficient to establish novelty- is not enough to establish an inventive step.
In practice, however, this is not a problem. "Whenever something is defined as being micro, there's usually a whole lot of other features specifically new and not obvious anyway," McGinley says.
Besides, much of the appeal of MEMS and the motivation to patent new devices resides in other factors. The growing degree to which devices integrate mechanical structures and associated electronics in single packages, which can be produced in large batches, cuts costs and brings improved reliability, faster response times, lower noise, greater accuracy.
The flow of European patent application about MEMS became significant in the 1990s, when they were being handled by examiners with a background in semiconductor physics. "About 2001, though, when it was clear it had become more specialised, the area got its own team of dedicated examiners."
Hundreds of small companies are chasing this new technology, but there is no dominant player yet. The vast majority of patent applications come from the USA and Europe. A small number of US companies are very active - Hewlett Packard, IBM and Honeywell - though many applications also come from US university research labs.
"In Europe, French research institutes and companies in Germany are the main players, with smaller numbers of filings coming from the UK, Italy, the Netherlands and a few others." Very few come from the Far East, with the exception of Korea, where Samsung is active. Japanese applications, so numerous in other engineering disciplines, are strikingly few in number. The Japanese's primary interests are micromachines and miniature robots designed to perform specific tasks. Europe tends to focus more on systems with sensors, processors and actuators.
Patenting activity for MEMS is growing steadily. (click to enlarge)
Readers can check esp@cenet for the latest patent literature about MEMS general technology. For advanced searches, we suggest the symbols listed below.
Sector |
ECLA |
|---|---|
|
General Technology |
B81 |
|
Packages |
B81B7/00P B81C5/00U |
|
Pressure Sensors |
G01L9/00D G01L13/02C |
|
Accelerometers |
G01P15/08 |
|
Gyroscopes |
G01C19/00 G01P9/02 |
|
Micro-mirrors |
G02B26/08M4 G02B26/10 G02B26/00C |
|
Switches |
H01H1/00M H01H59/00B H01H50/00C |
|
Micro-fluidics |
B01L3/00C6M F04B43/04M |
|
Reactors and Mixers |
B01J19/00R B01F13/00M |
|
Ink-Jet Print Heads |
B41J2/01 |
|
Scanning Probe Microscopes |
G12B21/02 |
Brussels, April 2007
-
Journalists: Chris Stokes
- Expert Opinion: Colm McGinley, Adrian-Léon Gex-Collet, Paolo Polesello, Michael Niaounakis, and Martin Meister at the EPO, Jérémie Bouchaud at Wicht Technologie Consulting.
- Chart and Data Research: Henry Lehtiniemi, EPO
- Photo Portrait: Birgit Geike, EPO
-
Research and Co-ordination: Leo Giannotti, EPO
(1) The latest is the NEXUS III report, Market analysis for MEMS and
Microsystems III. 2005-2009. See http://www.wtc-consult.de/english/r_n3_e.html
(2) EP0625285