Held June 9-11 in Rosemont, Ill., this year’s Sensors Expo & Conference offered a rich technical program and a floor of fascinating exhibits. Nearly 200 exhibitors participated, introducing the latest wireless controllers, thermometers, glucose monitors, automotive subsystems, industrial automation systems, oil pressure gauges, smoke alarms, manufacturing materials, and other technologies.
Attendees could attend the “Data Acquisition and Analysis,” “Nano/MEMS Technologies,” and “Energy Harvesting” pre-conference symposia, followed by a dozen technical sessions comprising more than 50 presentations. Three of these sessions, “Transportation Infrastructure Monitoring,” “Green Sensing,” and “Machine Health and Predictive Maintenance,” were new to the conference.
Small was the name of the game, as many of the technologies on exhibit relied on microelectromechanical systems (MEMS). Some even used nanotechnology in their construction. Across the board, many of these new sensing approaches target portable, low-cost sensing needs for modern applications.
IIwhan Oh of the University of Illinois, Urbana-Champaign, offered a novel microfabricated electrochemical sensor for gas analytes that’s superior to gas-chromatography, mass-spectrometry, ionization mobility spectrometry, metal-oxide, and conducting polymer approaches (Fig. 1). Oh’s research team used selective chemistry to sensor gas molecules of interest. Then, they successfully combined oxime chemistry and cyanide potentiometry to build the bio-toxin sensor using micro- and nano-fabrication technologies.
Based on the company’s Touch User Interface (TUI), Somatic Digital’s eTouchBook combines printed pages with an electronic binding that provides touch sensitivity. Readers activate hyperlinks to Internet resources that then appear on a connected computer by simply touching the book with their finger. Available for licensing to book publishers, it uses Freescale Semiconductor’s MC33794 EGR nine-electrode E-field proximity sensor chip and the MC9S8SH8CTG 8-bit microcontroller.
GE presented a unique approach for using non-destructive infrared (IR) sensing for carbon dioxide (CO2) in mass-market applications (Fig. 2). Adrian Kouznetsov, engineering manager for GE Sensing Telaire Products, said this approach is better than conventional thermoconductive and electrochemical solid electrolyte approaches.
The GE system costs less and offers longer lifetimes (more than 10 years) and better accuracy than those other approaches. Also, there’s no corrosion resistance or hysteresis. It isn’t sensitive to other gases, and it resists common industrial and household substances. And, it can withstand high levels of shock and vibration.
Other presentations focused on surface-acoustic-wave (SAW), optical, fiber-optic, magnetoresistive, Hall Effect, and magnetic-field sensing technologies. The bi-directional model #A40-HR 20P from Visi-Trak Worldwide LLC, which uses giant-magnetoresistive (GMR) technology to monitor linear position controls, provides rugged sensing with resolution better than 0.0007 in. at more than 200 in./s (Fig. 3).
“Our new high-resolution linear positioning sensing technology fills a gap the market for cost-effective, reliable, and rugged design that delivers the precision required. While there are other precision technologies available, they do not provide the same reliability and repeatability at high speed,” said Jack Vann, Visi-Trak’s president and CEO.
“Our sensors are non-contact, which means less wear and longer life. More reliable sensors allow our customers to maximize manufacturing efficiency and productivity by reducing cycle time and downtime. That equals a direct and immediate increase in profitability,” he added.
Sensitec GmbH reported on its CD54000 family of current sensors, which have been improved to handle up to 150 A of peak currents—up to three times that of normal magnetoresistive sensors—at 5 V. The models in the CD54000 also come in a package that’s less than 100 mm thin.
The TLE4997 and TLE4998 Hall Effect programmable linear sensors from Infineon Technologies target industrial applications. These surface-mount devices feature three selectable ranges of ±50, ±100, and ±200 Tesla, a high-precision 12-bit-resolution output, and low ratiometric error from –40°C to 150°C.
And, Stanley E. Woodward, senior scientist at NASA’s Langley Research Center, presented an interesting talk titled “Electrical Sensors Without Electrical Connections.” He described a magnetic-field response sensor comprising a patterned loop of copper that’s open at both ends, replacing the inductor, capacitor, and resistor elements of a typical circuit. The copper pattern can be directly deposited on any smooth, non-conductive surface using standard metal techniques.
The method has been used to measure fluid and temperature concurrently, non-gaseous levels, displacement and rotation, proximity, and damage conditions. Also, it could be used to detect the dielectric charge in food, solidification, and chemicals. It can be used in corrosive and caustic environments. And, it eliminates the shortcomings of conventional sensors such as weight (due to sensor copper wiring), electrical arcing, sensor wire degradation, and the need to power the sensor when measurements aren’t taken.
For more from the show, see “MEMS Motion Sensors Lead The Way At Sensors Expo 2008” and “Wireless Applications Dominate 2008 Sensors Expo".