PANTHER Sensor Quickly Detects Pathogens

Researchers at MIT Lincoln Laboratory have developed a powerful sensor that can detect airborne pathogens such as anthrax and smallpox in less than three minutes.

The new device, called PANTHER (for PAthogen Notification for THreatening Environmental Releases), represents a "significant advance" over any other sensor, says James Harper of Lincoln Lab's Biosensor and Molecular Technologies Group. Current sensors take at least 20 minutes to detect harmful bacteria or viruses in the air, but the PANTHER sensors can do detection and identification in less than 3 minutes.

The technology has been licensed to Innovative Biosensors, Inc. (IBI) of Rockville, Md. In January, IBI began selling a product, BioFlash, that uses the PANTHER technology.

"There is a real need to detect a pathogen in less than three minutes, so you have time to take action before it is too late," says Harper, the lead scientist developing the sensor.

The PANTHER sensor uses a cell-based sensor technology known as CANARY (after the birds sent into mines to detect dangerous gases), and can pick up a positive reading with only a few dozen particles per liter of air.

The device could be used in buildings, subways and other public areas, and can currently detect 24 pathogens, including anthrax, plague, smallpox, tularemia and E. coli.

"There's really nothing out there that compares with this," said Todd Rider of Lincoln Lab's Biosensor and Molecular Technologies Group, who invented the CANARY sensor technology.

Rider started developing CANARY in 1997 when he realized that there were no sensors available that could rapidly detect pathogens. His idea was to take advantage of nature's own defense system--specifically the B cells that target pathogens in the human body. "B cells in the body are very fast and very sensitive," Rider says.

The CANARY concept uses an array of B cells, each specific to a particular bacterium or virus. The cells are engineered to emit photons of light when they detect their target pathogen. The device then displays a list of any pathogens found.

CANARY is the only sensor that makes use of immune cells. Other available sensors are based on immunoassays or PCR (polymerase chain reaction), which take much longer and/or are not as sensitive as CANARY.

Rider and colleagues first reported the success of CANARY (which stands for Cellular Analysis and Notification of Antigen Risks and Yields) in the journal Science in 2003. Since then, they have been working to incorporate the technology into a portable device that could be used in a variety of settings where environmental threats might exist.

The new device, PANTHER, takes the CANARY technology and combines it with an air sampler that brings pathogens into contact with the detector cells. The prototype sensor is about a cubic foot and weighs 37 pounds and is well suited to building-protection applications. With minor modifications it could also enhance biological detection capabilities for emergency responders.

CANARY has been tested in rural and coastal environments as well as urban ones. It could eventually be used on farms or in food-processing plants to test for contamination by E. coli, salmonella, or other food-borne pathogens.

Another potential application is in medical diagnostics, where the technology could be used to test patient samples, giving rapid results without having to send samples to a laboratory.

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Rat Whiskers Yields Insight Into Sensing Machinery

High-speed video of rats using their whiskers to explore different surfaces has given researchers significant insights into the subtle mechanics of their tactile sensory system. Such information is important because the rat tactile machinery is a widely used laboratory model for studying how energy from sound or touch is translated into neural activity. Thus, basic insights from studying the rat system could aid in understanding the senses of hearing and touch in all mammals, including humans.

Christopher Moore and colleagues published their findings in the Feb. 28, issue of the journal Neuron, published by Cell Press.

Previous studies of the mechanics of rat whiskers had analyzed the motions and neural signals generated by isolated rat whiskers, rather than the complex, subtle “micromotions” of the array of whiskers, called vibrissae, in a behaving animal.

“Research has proceeded without a thorough understanding of these signals because the inherent challenges in tracking high-speed, small-amplitude motion of thin vibrissae in a freely behaving animal precluded direct measurement of micromotions,” wrote the researchers.

In their experiments, the researchers trained rats to use their whiskers to discriminate between rough and smooth surfaces in a darkened chamber. Their reward for performing correctly was a sip of chocolate milk.

Using high-speed videography, the researchers recorded the subtle vibrations of the whiskers as the animals probed the surfaces with their characteristic “whisking” motion.

Detailed analysis of these vibrations revealed how the different surfaces produced different micromotions. The rough surfaces produced what the researchers termed “stick-slip-ring” events—a kind of twanging of the whiskers. In contrast, smooth surfaces generated a stream of infinitesimal “stick-slip” oscillations.

The analysis also revealed how the different-length whiskers on the animals’ snouts exhibited different resonance characteristics, contributing to the animals’ acute ability to “see” their environment with their whiskers.

“The present findings provide the first description of what is believed to be an essential surface cue, micromotions of the vibrissae,” conclude the researchers. “In so doing, they address fundamental questions that had until this point remained unanswered, such as whether intrinsic biomechanics would impact transduction meaningfully during active sensation and what range of velocities are produced during free behavior.”

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Research May Allow Thirsty Crops to Signal Farmers

Corn and potato crops may soon provide information to farmers about when they need water and how much should be delivered, thanks to a University of Colorado at Boulder invention optioned to AgriHouse Inc., a Berthoud, Colo., high-tech company.

The technology includes a tiny sensor that can be clipped to plant leaves charting their thickness, a key measure of water deficiency and accompanying stress, said Research Associate Hans-Dieter Seelig of CU-Boulder's BioServe Space Technology Center. Data from the leaves could be sent wirelessly over the Internet to computers linked to irrigation equipment, ensuring timely watering, cutting down on excessive water and energy use and potentially saving farmers in Colorado millions of dollars per year, he said.

"We think this is an exciting technology, and the implications for the agriculture industry are enormous," says Seelig. Based in large part on Seelig's 2005 CU-Boulder doctoral thesis in aerospace engineering sciences, the technology was optioned to AgriHouse in March by the University of Colorado Technology Transfer Office, giving AgriHouse the exclusive right to negotiate a license with CU within 12 months.

Richard Stoner, AgriHouse founder and president, said existing technology like soil moisture sensors used to assess a crop's water needs do not always provide an accurate picture of existing plant and field conditions. "What we are developing is a non-intrusive device that gently rests on the plants and lets them interface with the digital world," he says. "Basically, this is a device that will allow plants to talk to humans and communicate their needs, like when to water and apply fertilizer."

Stoner is the principal investigator on a $150,000 Small Business Technology Transfer research grant awarded in May by the National Science Foundation to AgriHouse to develop the new technology. Seelig is an institutional investigator on the effort. In 2006, Seelig was awarded a $10,000 proof-of-concept grant for his research from CU's Technology Transfer Office.

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Tiny Sensors Could Aid Environmental Protection, Pharmaceuticals

By Emil Venere

Researchers at Purdue University have shown how to create a new class of tiny sensors for applications ranging from environmental protection to pharmaceutical preservation.

Although similar "gas-flow sensors" are currently being used for a variety of industries, the new sensor is the first that works on the scale of micrometers and nanometers, or millionths and billionths of a meter, respectively, said Steven Wereley, an associate professor of mechanical engineering.

Gas-flow sensors currently used, including those in residential gas meters to determine how much to charge customers, operate on a principle known for at least 100 years. According to that principle, as gas flows over a surface, such as the wall of a pipe or an object flying through the air, molecules of gas nearest the surface remain stationary. The molecules farther away from the surface move progressively faster.

"That model works really well in many situations, including aerodynamics and applications where the scale of the flow is large compared to the size of the molecules," Wereley says.

This principle, however, does not apply to gas flowing through channels on the scale of micrometers or nanometers, meaning ordinary designs will not work for sensors needed for applications on those scales. In such applications, gas molecules immediately adjacent to the wall of a tube do flow and are said to "slip."

"This exception to the model carries important design implications," Wereley said.

Findings will be detailed in a research paper to be published in the February issue of the Journal of Micromechanics and Microengineering. The paper describes how the sensor is designed.

Gas-flow sensors that operate on the scale of micrometers and nanometers could have applications in environmental protection, particularly to measure the leakage of hydrocarbon fumes from fuel tanks in new cars on the manufacturing line. Federal environmental guidelines specify how much leakage is allowable.

Automakers currently test empty fuel tanks by pressurizing them with a gas, such as helium, and then measuring whether the pressure drops, indicating leakage. The test is limited because, while it can determine whether a tank is leaking, it cannot reveal how severe the leak is. Using a sensor capable of measuring gas flow on small scales would make it possible to yield more accurate data.

An accurate test also could be applied to the pharmaceutical industry, which preserves drugs in packages filled with a gas free of the molds and impurities of ambient air. Pharmaceuticals are shipped and stored in the packaging, and the industry tests packages for leakage, but gas-flow sensors could be used to test them more accurately.

The Purdue researchers worked with industry to develop the sensors, which currently are too costly to be manufactured profitably. The research is associated with the Microfluidics Laboratory at the Birck Nanotechnology Center in Purdue's Discovery Park.


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System Detects Hazardous, Toxic Material in Concealed Packaging

Researchers at Sandia National Laboratories are developing the next generation of screening devices that will identify hazardous and toxic materials even if concealed by clothing and packaging materials.

Working in the underutilized terahertz (THz) portion of the electromagnetic spectrum that lies between microwaves and infrared, a team of Labs scientists is harnessing Sandia’s strengths in a variety of technical areas with the goal of building a highly integrated miniaturized terahertz transmitter-receiver (transceiver) that could make a number of applications possible.

The project, the Terahertz Microelectronics Transceiver Grand Challenge, is in its second of three years of funding through Sandia's internal Laboratory Directed Research and Development program.

Sandia is a U.S. National Nuclear Security Administration (NNSA) laboratory.

“The technology being developed in the Grand Challenge can be used to scan for items such as concealed weapons or materials, explosives, and weapons of mass destruction,” says Mike Wanke, principal investigator. “In addition, we believe it will find applications in advanced communication systems and high-resolution radars. However, the infrastructure needed to move the terahertz technology from the laboratory to the field is unavailable right now. We want to develop that infrastructure and invent the necessary technologies.”

Wanke says over the past three years, “the terahertz situation has begun to change dramatically, primarily due to the revolutionary development of terahertz quantum cascade lasers.”

These tiny lasers are semiconductor sources of terahertz radiation capable of output powers in excess of 100 mW. Previously, such powers could only be obtained by molecular gas lasers occupying cubic meters and weighing more than 100 kg, or free electron lasers weighing tons and occupying entire buildings.

Quantum cascade laser-based systems can be less than the size of a baseball and powered from a nine-volt battery. Sandia has been a leader in developing this new technology and in collaboration with MIT is responsible for several world performance records for the lasers. Also, the Labs and its partners are the only US institutions that have demonstrated the ability to grow the unique semiconductor crystals such that they can be turned into operating terahertz quantum cascade lasers. The crystals are grown by Sandia research scientist John Reno, an expert in molecular beam epitaxy, a method of laying down layers of materials with atomic thicknesses onto substrates.

Sandia researchers spent the first year of the Grand Challenge using Sandia’s unique strengths in integrated microelectronics and device physics to develop components that are now being combined to create an integrated THz microelectronic transceiver, a core enabling element.

The team is currently developing the receiver, doing systems tests and exploring packaging requirements. At the end of three years, the researchers expect to have an actual working prototype capable of detecting the materials and chemicals by reading distinctive molecular spectral “signatures.”

“Most materials and chemicals have their own unique terahertz spectral signatures,” Wanke says. “A terahertz transceiver system would be able to measure, for example, the signature of a gas and determine what it is.”

“Atmospheric scientists and radio astronomers have spent years developing terahertz spectral signature databases to identify chemicals in nebula and planetary atmospheres,” says Greg Hebner, program manager. “Even though the current devices are washing machine-sized, they are located in a few observatories, and one is even flying on a satellite. To address specific national security problems, we are working on reducing the size, weight, and power requirement as well as expanding the existing spectral databases.”

In addition to monitoring for concealed hazardous materials, Mike believes a terahertz system can be used to monitor the air for toxic materials. Using air sampling technology developed at Sandia and other locations, hazardous vapors can be preconcentrated. Shining light from the quantum cascade laser through the concentrated sample provides a direct identification of the vapor. This technology can be used in conjunction with existing mass spectrometer-based systems to reduce false identifications.


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