Electronic Design

MEMS And Nano Push For Higher System Integration Levels

Microelectromechanical-systems (MEMS) devices have matured into commodity market components whose use is growing in many familiar applications, such as consumer, automotive, medical, and environmental electronics.

Yet many MEMS device manufacturers now face the next challenge: tackling what lies beyond these present applications to enable MEMS usage in newer, more complex systems. For many of these companies, the next step is smart systems integration that includes not only the use of nano-sized devices, but also many different functions that involve many different materials.

Much of this was evident from a number of technical presentations and panel session discussions at November’s MEMS Industry Group (MIG) MEMS Executive Congress Meeting. Attendees and speakers explored and debated how to cost-effectively achieve greater levels of system integration to capture these potential applications.

The “systems” in MEMS is taking on a new meaning, emphasizing the device and its supporting circuitry and how they are applied, not just the device itself. The challenge is to “think outside the chip,” as Roger Grace of Roger Grace Associates noted at the conference, and work more closely with the end customer. This includes getting involved with chip(s) partitioning, signal-conditioning, software and firmware development, packaging, and testing issues, each of which may be unique to a particular application.

This systems-level approach will be the theme of the Smart Systems Integration 2010 Conference this March in Italy (see “Smart Systems Integration 2010”). It takes into consideration not just MEMS devices, but also nano-scale devices (sometimes called nanoMEMS or NEMS), different types of materials, various signal sources, and the entire package needed to house a cost-effective product solution.

NEMS could be the next big thing in semiconductors, said Raj Jammy, vice president of emerging technologies at the Sematech Manufacturing Consortium. And speaking at the recent IEEE International Electron Devices Meeting (IEDM), Dennis Pola, who manages NEMS research at the U.S. Department of Defense’s Advanced Research Projects Agency (DARPA), said that his agency considers NEMS “the next revolution in miniaturization.” Jammy, however, decries the fact that few people are investigating how to integrate NEMS with CMOS technology.

The consensus at the MIG MEMS Executive Congress Meeting was that a systems-level approach is needed to enable many new applications. Even the consumer electronics sector, which widely uses commodity item MEMS motion sensors, is open to innovations.

Consider the approach that Hillcrest Labs took while it was developing its low-cost Loop pointer in-air user interface for Internet entertainment (Fig. 1). “The key to our product’s development is largely in the software we developed. This is the foundation for a broadband interactive user interface,” said Chad Lucien, vice president for free-space products at Hillcrest Labs. “Software development constituted most of the cost.”

Hewlett-Packard Labs has developed a small, ultrasensitive inertial MEMS accelerometer platform that’s 1000 times more sensitive than high-volume commercial accelerometers yet is low in cost (Fig. 2). It leverages HP’s own MEMS fluidic technology and is part of the company’s grand future vision, which it calls Central Nervous System for the Earth (CENSE). HP is not selling this sensor as a commodity component, though.

“We plan to piggyback this sensor with other sensing elements and electronics and partner with others to devise a wireless sensing system solution,” said Grant Pease, business development manager at HP’s Technology Development Organization.

“A major application for our sensor is roadway monitoring as part of the Intelligent Transportation System laid out by the U.S. Government’s Department of Transportation that can provide large energy savings on roads and freeways. We can easily modify this sensor’s performance to fit specific application needs, like a greater number of axes, more bandwidth, etc.,” Pease said.

SOARING bioMEMS GROWTH

MEMS and nano devices, coupled with wireless communications technology, will propel the market for medical devices. Some estimates put that worldwide market at several hundred billion dollars within a few years.

Implantable medical devices are a hot area. MEMS and nano devices will be increasingly implanted in hips, spinal cords, brains, and other areas of the body for more sophisticated and improved diagnostic and therapeutic medical applications. Such smart implants will target diseases including cancer, as well as a host of neurological disorders like lupus and fibromyalgia.

In its report, “2020: A New Drug Delivery Landscape,” Cambridge Consultants provides a snapshot of current and future drug-delivery scenarios. Andrew Diston, global medtech practice leader at Cambridge Consultants, sees vast growth in the drug-delivery world.

“The world of pharmaceutical delivery is poised to realize many of the benefits of technological advances from other industries, where standards are reaching towards the requirements for medical applications,” Diston said. “Reliable microelectronics platforms may provide significant additional functionality and connectivity for new delivery devices, presenting great opportunities for innovative pharmaceutical companies and startups to play a part in this healthcare revolution.”

A team led by Jeffery T. Bornstein at the Charles Stark Draper Laboratory is working on one such promising drug-delivery development to treat a common form of hearing loss that affects more than 250 million individuals worldwide. Funded by the U.S. Institutes of Health, the micro-scale system is flexible enough to be implanted under a patient’s earlobe (Fig. 3).

The system delivers tiny amounts of a liquid drug to a very delicate region of the ear, allowing sensory hearing cells to regrow, ultimately restoring the patient’s hearing. A polymer material is used due to its flexibility.

The implanted device consists of a programmable micro-controlled micro-pump powered by a small battery. It pulses precise drug doses from a reservoir that holds enough medication to last about a year, after which the patient can refill it via a minor surgical procedure.

The present battery is a D cell. However, the researchers are actively trying to miniaturize the implantable device and make it operate from a single AA battery cell. Clinical trials are expected within five years.

MEMS and nano technologies are sure to play a large role in remote medical diagnostics. One impressive development, a stick-on patch for remote cardiac patient monitoring, comes from the Mayo Clinic in collaboration with STMicroelectronics. Worn on the chest, the patch continually monitors a patient’s heart by sensing and transmitting various physiological parameters.

The ultimate point-of-care medical device is the lab-on-a-chip, which will provide medical doctors with a low-cost tool to quickly diagnose a patient for bacterial and flu infections as well as cardiovascular and cancer diseases. Most recently, scientists at the IBM Research Center in Zurich, Switzerland, working with Switzerland’s University Hospital in Basel, created an innovative one-step single-chip prototype diagnostic tool (Fig. 4).

The microfluidic chip measures about 1 by 5 cm and comprises channels that are 180 µm deep and range from 30 to 100 µm wide. Bodily fluids such as blood are deposited on the chip. After about 15 seconds, the chip can be inserted into a fluorescence reader, which is standard equipment in many medical facilities, for quick test results.

The chip requires only 5 µliters of a blood sample, which is just a pinprick amount. Belgium’s Coris BioConcept plans to commercialize the device within two years. The present prototype can be used for testing one bodily fluid. However, IBM is working a version that can test six substances simultaneously.

“It is important for medical device manufacturers to show the medical community that the use of MEMS and nano devices can provide them with a profitable revenue model. This is a business issue,” said Doug Lee, CEO and chairman of OrthoMEMS, a medical device spinoff from the Cleveland Clinic, during a bioMEMS panel session at last year’s MIG MEMS Executive Congress Meeting. “The clinician must be a vital partner in all aspects of the medical device’s conception, design, and manufacture for the product to succeed.”

A keynote presentation at that meeting reinforced the idea of one untapped application with amazing possibilities, using nanoscale devices in the biomedical field. In his presentation, “Silicon as a Medical Material,” professor and medical doctor Mauro Ferrari of the University of Texas Health Sciences Center outlined how silicon is more bio-compatible for drug delivery and therapeutic applications than any other material.

Ferrari, who is widely considered the father of bioMEMS, described a personalized molecular drug-delivery system (PMDS) that he and his team of more than 100 scientists have been working on for the National Aeronautics and Space Administration (NASA) that will be ready for commercialization within the next few years. He has formed a company, NanoMedical Systems Inc., to do just that and expects to have its first silicon-based bioMEMS implants ready for clinical trials within a year.

“I am looking at silicon as a fundamental medical material for curing cancer,” said Ferrari. “We have used microfluidics with extremely tiny channels and reservoirs as small as 57 angstroms to dispense drugs and test biological samples into the body’s biological fluids for early cancer detection and treatment.”

Such targeted drug delivery is much more accurate and has fewer side effects, if any, compared with conventional cancer-fighting approaches. Ferrari foresees the possibility that “within a decade, we may very well be able to detect cancer early enough and treat it, well before other drastic measures are needed.”

AUTOMOTIVE ELECTRONICS: A KEY MARKET SECTOR

The automotive electronics arena is one key area where smart systems integration can provide more cost-effective solutions. The advent of dozens of sensors in a car, all performing different functions, has given rise to the term sensor fusion. This generally refers to greater signal performance from sensors by combining sensory outputs from many sources.

“We cannot continue to add more electronics to a car without addressing the rising level of electronics complexity in the vehicle. We need to improve electronics optimization and take a system-level approach. We should add intelligence in a car where it is needed, not just add complexity,” said Pietro Perlo, director of the Technology Division for Fiat, during a MEMS Automotive panel session at last year’s MEMS Executive Congress Meeting.

“This is true for even Germans,” said Reiner John, senior manager for Germany’s Infineon and a participant on the same panel.

“Bringing together all the circuitry related to the sensor, like power, processing, interfacing, communications, etc., and providing redundancy is what’s needed in cars,” said panelist Jean Krayer Pitz, sensor, interface, and power products technologist at the Texas Instruments mixed-signal automotive group. She favors a sensor fusion approach wherein more sensors are packaged within the same module.

“The automotive sector is a leading-edge area where a systems-level approach in a single module is becoming the norm,” said Rob O’Reilly, senior member of the technical staff at Analog Devices’ MEMS and sensor technology group. “It is vital that a MEMS sensor manufacturer cover the entire signal chain no matter what the application.”

There’s no doubt that hybrid and electric cars are appearing in larger numbers, though this depends on where you live. “It would be stupid not to work on developing an electric car,” said Fiat’s Pietro Perlo. “But we better have the electric resources to supply that energy. Right now, it’s coal-burning energy that we have to work on to improve carbon emissions.”

INDUSTRIAL APPLICATIONS GALORE

MEMS technology is also active in enabling more efficient fluid control in heating, ventilating and air-conditioning (HVAC) systems, refrigeration/cooling, and automotive transmission applications, as demonstrated by Microstaq Inc. Its Ventillum chip silicon expansion valve is much smaller than the conventional 50-year-old valves in use today (Fig. 5).

“The valve allows the movement of tens and hundreds of liters of fluid, with nanometer and micrometer accuracy,” said Sandeep Kumar, Microstaq’s CEO. “This truly groundbreaking technology addresses the needs of those using expansion valves to control large amounts of fluid and will have huge ramifications.” The company says this product has the potential to reduce global energy consumption by more than 1.2 billion barrels of oil per year.

Testing MEMS and nano devices has always been a big challenge since no two devices share the same package, much less the same functionality. But a team of European researchers has developed a way to test hundreds of MEMS structures at once to reduce inspection times from 20 minutes to less than 30 seconds.

Developed by the European Union, the system is called SMARTIEHS, or SMART InspEction systems for High Speed and multifunctional testing of MEMS and MOEMS. SINTEF ITC, the Scandinavian research organization, is coordinating the project.

SMARTIEHS uses an array of interferometers that can accurately identify an object’s shape, changes in shape, and vibration. The plan is to use specially designed glass wafers with as many as a hundred interferometers and to test 100 circuits on a MEMS wafer in one try. The scientists will be able to measure the shape, deformation, and resonant frequency of the MEMS chips and thus identify manufacturing faults.

When the project is finished by the end of 2011, the research teams expect the demonstrator to be expanded to 50 channels. The researchers also believe this design will enable the number of channels to be easily increased to 100.

TAGS: Automotive
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