Sensors: More than MEMS

The fact that I spend too much time focusing on consumer electronics was brought home to me vividly by a visit to the recent Sensors Expo 2011 in Chicago. Far from the niche show that I expected, it was swamped by over 4,000 attendees checking out 140 exhibiting companies, making navigating the aisles a good application for GPS, LIDAR, a 3-axis accelerometer and a collision-avoidance system.

While the bulk of the $9.7-billion U.S. sensors market comprises MEMS-based accelerometers—the not-so-secret sauce behind the 34 million Wii game consoles sold to date—there were plenty of other sensor technologies on display, including proximity, light, piezo-electric, thermal, pressure, touch, gas, chemical, IR and probably more that I missed. The applications consisted of a wide range of consumer, industrial, medical, environmental and security devices, all of which relied on sensor data for input. If you can’t measure it, you can’t control it, and that’s the problem this show addressed.

On with the show
Instead of rolling out individual products ROHM Semiconductor chose to showcase a number of them at once with its Sensor Race Track, which featured a model Hummer circuiting a track populated with nine different sensors:  three-axis accelerometers, an ambient light sensor, a UV sensor, a Hall effect sensor, an optical proximity sensor and an inclinometer. All of these inputs fed into a sensor hub and then to a wireless networking module, which in turn presented the data in real time on a large screen.

Digi International used Google Earth to demonstrate its “cloud-based wireless sensor network,” which enables centralized monitoring and control of disparate resources worldwide—from rotating solar panels to tracking trucks to monitoring vending machines—all using wireless sensors nodes connected to the internet.

Some companies such as ROHM, Epson, MEDER and many others displayed numerous individual sensors; others showed products that could integrate data from different sensors—so-called sensor fusion. STMicro highlighted its iNEMO inertial measurement unit (IMU) devices, which combine data from various motion sensors with magnetic (compass), barometric/altitude and GPS data to enable location-based services. ST stressed the low-power angle, a theme echoed by TI, Maxim, Microchip, Linear Tech, Analog Devices and most other vendors. The chip companies, by and large, focused on managing the power going to and the data coming from remote sensor devices.

Energy harvesting
A number of companies focused on extending the useful life of remote sensor nodes by using energy scavenging techniques. Cymbet uses a combination of tiny solar panels backed up by their proprietary thin-film batteries to supplement coin cells in wireless sensor nodes; Microchip and TI, among others, rely on Cymbet’s board to power their energy scavenging kits.
Powercast pulses RF from a central source to top up power in and gather data from remote sensor nodes. The Powercast P2110 receiver is an RF energy harvesting device that converts RF to DC and stores it in a capacitor. The Powercast transmitter can power an array of battery-free receivers throughout a building for industrial monitoring, HVAC and smart-grid applications—all of which resembles a wide-area active RFID system.

Nextreme’s miniature, embedded thermoelectric generators (eTEG) are essentially thin-film thermocouples that fit between a heat source (MCU, PA, etc.) and its heatsink. Converting temperature differences of as little as 5°C into electrical power, the eTEG is designed for powering gas sensors; trickle-charging wireless sensors in dark or remote places; and improving fuel efficiency in automobiles.

Sensors VC
If you missed the show there’s another sensors conference coming up next week—online. On Thursday, June 23 EE Times is presenting the Sensors Virtual Conference: New Frontiers in Monitoring and Control. The not-to-be-missed keynote will be MEMS Evolution and New Applications, presented by Stephane Gervais-Ducouret, VP of Global Marketing, Sensors, Freescale Semiconductor, Inc.

There are panels covering Sensors in Handheld Designs, Low-Power Wireless Sensor Networks, and Medical, Environmental and Security Applications where you ask your questions directly to industry expert. Yours truly will be moderating two of the panels. There are also sponsored chats and vendor booths (virtual, of course) where you can get direct access to FAEs.
If you’re working with sensors, or sensors are on your horizon, check out the show. It’s free, doesn’t require a travel budget, and promises to be information dense. Mark your calendar: Thursday, June 23. ‘See’ you there!


John Donovan is editor of www.low-powerdesign.com