Info Exchange - Nanotechnology and Micro System Association

MUNICH, Germany — Analog or Digital? In industrial process measurement and control, this is still the question. And although the question is simple, and despite the increasing digitization of electronics, the answer remains complex.

Sensor hardware increasingly integrates digitalization circuitry and digital interfaces. Some control applications require many different inputs and the multivariable processing is so complex that it only can done digitally. In some application cases however, analog continues to dominate.

Sensors which offer digital output signals inherently need to be equipped with integrated circuitry such as ADCs and serializers. For this reason, MEMS-based sensors are particularly well suited for this kind of digitalization, since they typically are manufactured in much the same way and using the same materials as integrated circuits.

“The combination of MEMS and integrated electronics enables the design of solutions which in conventional technology would require complicated signal processing chains end in many cases offline processing”, explained Frank Guidone, CEO of Measurement Specialties Inc., (Hampton, VA) which has a strong R&D presence in Europe.

At the recent Test+Sensor trade show in Nuremberg, Germany, the company showed a MEMS-based lubrication oil quality sensor that illustrates the complexity of modern sensors. The device comprises a MEMS tuning fork that simultaneously measures different properties of a fluid such as viscosity, density, dielectric constant and temperature. By combining all these values, it derives information as to the degradation of the lubricant within less than a minute. Used in heavy trucks, such sensors do away with offline oil analysis in a separate lab and inform truck operators on-the-fly when an oil change is needed – a clear economic advantage in today’s landscape of rising oil prices, said Guidone.

Analog Devices Inc. (Norwood, Mass.) follows a similar approach in combining a MEMS sensor with integrated processing logic. The company showcased its recently launched ADXL001 industrial vibration and shock sensor.

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