Microlever Sensing
Nevada Nanotech Systems believes that the ultimate problem in the trace detection of chemicals, biological agents, and explosives hidden in cargo is sampling. This methodology means more sensors are needed in more places to successfully tackle the sampling challenge.
As a result, the company opted to develop a self-sensing array (SSA) based on micro-cantilevers to detect chemicals, biological agents, and explosives. Nevada Nanotech Systems believes that this technology can be realized in a device that measures just two cubic centimeters, runs on a watch battery, and costs only a few hundred dollars.
Nevada Nanotech Systems successfully tested the system against seven chemical agents, including toxic industrial chemicals like ammonium hydroxide, toluene diisocyanate, formaldehyde, and allyl alcohol. The SSA also detected serratia marcescens, a biological agent analog to the plague, among other bacteria using a new technique. And, the system detected explosives vapors from trinitrotolune (TNT), pentaerythritol tetranitrate (PETN), and cyclotrimethylene trinitramine (RDX).
Ultrasound is one of many technologies being employed in detecting illegal materials in cargo shipments. Researchers at the Pacific Northwest National Laboratory (PNNL) came up with a prototype portable handheld hazardous-materials acoustic inspection device. It non-invasively interrogates and identifies fluids in sealed containers by using ultrasonic velocity and attenuation measurements. PNNL believes such a system would be invaluable in homeland-security applications.
Another potentially important technology is optical frequency combs. Researchers at the National Institute of Standards and Technology (NIST) demonstrated a novel system based on these combs, which can detect a wide variety of molecules in tiny trace amounts at high speed. Possible applications include explosive detection at airports, chemical analysis in labs, and pathogen detection for homeland security and healthcare. NIST conducted these experiments jointly with the University of Colorado at Boulder.
IR thermal imaging, particularly the development of lower-cost uncooled IR imagers, is another rapid-growth technology. Analysts estimate that the market for IR imaging and night-vision cameras and systems adds up to as much as $2 billion. These imagers also are referred to as microbolometers.
The cost for uncooled IR thermal-imaging arrays runs about half the price of conventional cooled imagers. Also, they're smaller and feature quieter operation. However, this comes at the expense of lower sensitivity, slower response time, and the need for optics to achieve longerrange performance. Cooled mid-wavelength IR imagers could mitigate some of these drawbacks.
Novel manufacturing methods like that used by Electro-optic System Design promises the volume production of silicon MOEMS (micro-optical electromechanical systems) passive IR sensors for $100 to $500. The mosaic-pixel, focal-plane-array (FPA) design contains a number of individual microbolometer detectors that are electrically interconnected to form an imaging pixel.
Two versions were successfully produced and tested. A small-format large-pixel short-range FPA (up to 25 m) was designed for hot-spot detection in the early stages of a fire. A longer-range version (up 100 m) targets security applications.
RedShift Systems, a pioneer in low-cost thermal-imager development, now supplies its Thermal Light Valve to OEMs for use by first responders, firefighters, and law-enforcement officers, as well as in automobiles. Meanwhile, Lucent Technologies Bell Labs and Isonics Corp. entered into a three-year cross-licensing agreement to produce MEMS IR sensors for defense and homeland-security applications. The agreement contemplates a proof of concept demonstration by the end of this year, followed by commercialization.