Nano sensors, everywhere
Think Again: Micromachining techniques are shrinking sensors, making devices less expensive with more capabilities. Microelectrical mechanical systems (MEMS) will evolve into nanoelectrical mechanical systems (NEMS).
Where there are sensors (and everyone seems to agree there are going to be many more of them) control loops make them more useful. The control loop (sense-decide-actuate and repeat to optimize) can be open-loop control where humans are involved to help analyze data and actuate a decision, or closed-loop control where that is automated.
Micromachining technologies are helping sensors evolve into smaller and less-expensive devices, explained Jean Philippe Polizzi, micro and nano systems program manager, CEA LETI, in a June 25 presentation at Sensors Expo. Consumer applications for sensors have opened markets for MEMS technologies, providing benefits to industrial and other markets, while creating cost and integration challenges.
Traditional MEMS technologies are showing their limits, he suggested, while new techniques are being developed to overcome these limitations.
Smaller, more integrated
As micromachining techniques get smaller, it is appropriate to consider a name change from microelectrical mechanical systems (MEMS) to nanoelectrical mechanical systems (NEMS).
CEA LETI, based in Grenoble, France, creates and transfers technology to industrial partners, from basic research to mass production. Silicon microelectronics is about half of what the organization does, Polizzi said.
Progress in MEMS platforms has been significant, Polizzi said, with:
- Weight sensors in 1980, humidity sensors in 1981, quartz accelerometers and electrostatic micromotors in 1987, accelerometers in 1995, pressure sensors in 1998, telecom optical switches in 2001, consumer accelerometers in 2007, and gyro in 2010 in the Apple iPhone4.
- In the 1980s MEMS sensors were applied to aircraft, in the 1990s to cars, in the 2000s to phones, and in the 2010s to many apps across industries, to become a billion-dollar market.
- For manufacturing, there was bulk micromachining in the 1980s, surface micromachining in the 1990s, and silicon-on-insulator MEMS (SOIMEMS) micromachining in the 2000s.
What's next for NEMS
What's next in the 2010s?
LETI, Polizzi said, is looking into physical, chemical, and biochemical sensors. Trends include pressure for smaller devices, and more integration of multiple features and functions into one design. Sizes are in the 500 um to 10 um (10 micron) range. Decreased sizes often require new technologies for manufacturing, and this is where it really gets fun, with a mix of micro and nano processes now being applied to various portions of the same device to optimize the die area, all with the goal of decreasing size, integrating more functionality, increasing resolution and sensitivity, and lowering cost.
Think again about next-generation applications of nano-sized elements being applied to accelerometers, gyroscopes, pressure sensors, microphones, and gas chromatographs. Ongoing efforts include CEA-LETI cooperation with Caltech.
- Mark T. Hoske is content manager, CFE Media, Control Engineering, email@example.com.
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Philippe Polizzi, micro and nano systems program manager at CEA LETI, has been involved for more than 20 years in the field of microsystem-based product development in different companies and institutes. At SAGEM, he participated in micromachined pressure sensors and accelerometers development for the automotive market. He joined Auxitrol in 1997 as the pressure sensor group manager, where he developed MEMS-based aerospace sensors. Beginning in 2002, he was the head of the MEMS group in Thales Corporate Research Centre, developing RF switches and piezo-electric devices. He is currently in charge of strategy and business development for the MEMS sensors and actuator activity at CEA LETI.
LETI is an institute of CEA, a French research and technology organization with activities in energy, IT, health care, defense, and security. LETI is one of the main European applied research laboratories working on miniaturization techniques (microelectronics, sensors, and microsystems) and applications ranging from space to smart devices in fields such as transport, biology, health, environment, photonics, and security. A bridge between basic research and mass production, its main mission is to create innovation and transfer it to industry through applied research and pilot production. In the specific domain of MEMS sensors and actuators, more than 150 researchers continuously create, develop, and improve new components and technologies in an up-to-date 1000m² MEMS 8-in. line.