Sensors do more with less

MEMS-based accelerometers are one of the fastest growing segments of the industry. Shown here is an accelerometer seismic mass with support hinges from Silicon Microstructures, Milpitas, Calif.

Advances in silicon-fabrication techniques are making it easier to combine computing power with the tiniest of sensors. The resulting new generation of smart sensors can not only communicate with one another to share data and configuration information, but also talk with controllers far away.

Helping to make sensors smarter is the new IEEE P1451.4 standard. The plug-and-play spec calls for sensors to include an embedded chip containing transducer electronic data sheets, or Teds, that store parameters for self-identification and self-description. Teds promise to simplify sensor set up, use, and maintenance by automatically gathering calibration data, eliminating time-consuming manual methods and potential errors. It should make the process of integrating sensors into systems as easy as plugging a mouse into a computer. Companies on board include National Instruments, Macro Sensors, Endevco, and Transducer Techniques, among others.

The ability to put more computing power on the sensor is eliminating the need for some ancillary electronics and software. In the past, sensors just gathered data. Now, smart sensing systems can analyze and manipulate captured data before sending it back to a computer, eliminating a/d converters and lightening the computational load on system controllers.

The steady growth of MEMS, or microelectromechanical systems, is also having more of an impact. MEMS technology has become commonplace in sensing pressure, acceleration, and attitude. But the next generation of MEMS devices will look more like microsystems than sensors.

A wireless MEMS device, such as this implantable sensor from CardioMEMS, Atlanta, Ga., can transmit blood flow and pressure data to external devices.

The new paradigm is to integrate MEMS with microcontrollers and communication links into a single package. The resulting sensors can gather data, process and analyze it, and send it over a wireless link.

For example, work on sensors with wireless front-ends built in is underway at the University of Michigan. Thanks to a National Science Foundation grant, the school has set up a Wireless Integrated Micro Sensor laboratory.

MEMS offer the advantage of high-volume production, lowering cost. Because they're manufactured in a clean room, mass production offsets the high capital investment. MEMS sensors are also relatively small and can squeeze into tight places where ordinary sensors can't. This is especially important in biomedical applications where sensors may need to be implanted in the body.

MEMS-based sensors are expected to grow in areas that include medical infusion pumps, oxygen concentrators, hemodyalisis machines, and blood glucose monitors. Automotive applications will also be big for inertial sensors and tire-monitoring systems. Other areas are biometric ID systems, photonics, electronic warfare systems, and chemical biosensing, all of which are critical for homeland security and environmental monitoring.

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