More than MEMS

The fact that I spend too much time focusing on consumer electronics was brought home to me vividly last week by a visit to the 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 $9.7B U.S. sensors market is MEMS-based accelerometers—the not-so-secret sauce empowering 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—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:  3-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.

About John Donovan

Writer, editor, Dad
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