Using National Instruments Software and Hardware to Develop a Highly Accurate and Portable Device for Detecting Explosives

Author(s):
Frank Bouchier - Sandia National Laboratories

Industry:
Government/Defense

Products:

The Challenge:
Creating a portable, low-cost device for the trace detection of improvised explosive devices (IEDs) and other contraband.

The Solution:
Combining patented sample collection and preconcentration technology from Sandia National Laboratories with National Instruments software and hardware to design a highly flexible and accurate detection system.

The development of the MicroHound^® handheld explosives detection system was a quest to combine, in a single platform, a miniaturized sampling and preconcentration system with multiple, highly sensitive chemical microsensors capable of detecting nanogram amounts of explosives. This lightweight system weighs about two pounds and can detect explosives in vapor and particulate forms by using two sampling methods, vacuum inhale and swipe. The long-term goals of the project were to reduce the size, weight, and cost of a handheld trace explosives detection system and to use a multisensor platform to improve functionality. The sampling and preconcentration technology used in the MicroHound was originally developed and patented by Sandia for an explosives detection personnel portal.

One of the biggest obstacles in detecting explosives is quickly testing suspicious items and surfaces in the field, and returning the results of the analysis very quickly so responders can make decisions and take action. In addition to the physical challenges of sampling tiny amounts of material and routing the samples to the detectors, the unit must also gather information and communicate results quickly.

At Sandia, we used the National Instruments PCI-6025E multifunction DAQ device, along with the National Instruments LabVIEW Real-Time, to develop the MicroHound system, which uses a miniature ion mobility spectrometer (IMS) detector, the Sandia MicroChemLab™ (an integrated micro-preconcentrator, micro-gas chromatograph, and surface-acoustic wave sensor), and large-volume sampling preconcentration technologies.

Operations

To collect a sample, the operator can use the “contactless” vacuum mode, which “sniffs” the air surrounding a suspicious item, or the swipe mode, which lets the operator wipe particulate matter from the surface of a suspicious item. In vacuum mode, the operator presses a button to draw a large volume of air into the sampling unit, where heavy organic compounds collect onto a filter. A separate input port collects samples of high-vapor-pressure compounds on the MicroChemLab micro-preconcentrator. In swipe mode, the operator swipes the surface of a suspicious object, places the filter in a holder, then places the holder into the unit.

Pressing a button on the handle initiates analysis once the sample is collected. The system vaporizes the compounds collected on either filter into a concentrated sample that is delivered to the IMS detector. The NI PCI-6025E collects and analyzes spectra from the IMS using NI LabVIEW Real-Time software. In parallel, the MicroChemLab analyzes the collected sample and communicates the results to the host system. If either detector finds contraband, the unit displays an alarm to notify the operator.

Hardware and Software Controls

Previous applications required larger computers for control and analysis or dedicated hardware that limited flexibility. A major challenge in developing this system was to maintain the flexibility required of a research tool, as the system was miniaturized to the size of a production commercial instrument. The combination of a powerful Pentium-based computer with NI LabVIEW Real-Time allowed us to meet this and other challenges associated with the new system.

We built the unit’s computer from a pair of stacked PC/104 cards, which measure approximately four inches by four inches. This stack is coupled with the NI PCI-6025E, which provides a range of functions to meet the system’s needs. The card’s analog-to-digital functions record IMS spectra and monitor several temperature and pressure sensors. Digital I/O lines monitor switches and turn fans and pumps on and off. Analog outputs control the preconcentrator heater. One of the device’s counters provides a required gate pulse for the IMS. We wrote all the onboard software in LabVIEW Real-Time, providing accurate timing control of all operations.

The operator controls the system via a small set of push buttons. All system status messages and analysis results are displayed to the user through an eight-line-by-60-column LCD screen. Raw data for the onboard instruments are stored locally on a CompactFlash card. Ethernet communications allow easy software updates and data downloads. We also wrote a companion program to allow scientists to analyze the data in detail, which means that the system can operate in a mode similar to a benchtop system when connected to a host computer. The operators control all operational parameters through this interface.

Applications

While the MicroHound is designed for use by the responder community to examine suspicious packages and to screen surfaces at checkpoints, its low cost, light weight, and effectiveness make the it an ideal tool for adoption in civilian infrastructures, such as courtrooms and schools, as well as in high-security, high-risk facilities and locations.

For more information, contact:

Frank Bouchier

Sandia National Laboratories

P.O. Box 5800-0782

Albuquerque, New Mexico

Tel: (505) 845-8382

Fax: (505) 845-8382

E-mail: fabouch@sandia.gov

 

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