Scientists at Georgia Tech Research Institute have developed a small electronic sensing device that can alert users wirelessly to the presence of chemical vapors in the atmosphere by integrating RFID technology with sensing devices.
The technology could help New York City and other major cities to fight off terrorism, while also finding a wide range of uses in healthcare, manufacturing and military applications.
Because it is based on programmable digital technology, the RFID component can provide greater security, reliability and range – and much smaller size – than earlier sensor designs.
“Production of these devices promises to become so inexpensive that they could be used by the thousands in the field to look for telltale chemicals such as ammonia, which is associated with explosives,” says Judy Song, a GTRI senior research scientist who is principal investigator on the project.
“This remote capability would inform soldiers or first responders about numerous hazards before they encountered them.”
Song says that wireless sensors could also be valuable for identifying and better understanding air pollution. Inexpensive sensors that detect ammonia and nitrogen oxides could be fielded in large numbers, giving scientists increased knowledge of the location and intensity of pollutants.
The availability of such chips might also help companies detect food spoilage. And healthcare facilities could benefit by detecting all kinds of human biological conditions, and by informing caregivers of patient conditions and potential biohazards.
“By using passive RFID you can put billions of these sensors all over the place and have them be continuously monitoring for chemicals or vapors and you don’t have to be near them to maintain the sensor because it’s passive, so there is no battery,” says Christopher Valenta, a GTRI research engineer who is co-principal investigator on the project.
“So from a very far distance you can interrogate the sensors and find out if there is any chemical presence in the vicinity without getting even remotely close to the area.”
The present GTRI prototype is 10 centimeters square, but future designs are expected to squeeze a multiple-sensor array and an RFID chip into a one-millimeter-square device printable on paper or on flexible, durable substrates such as liquid crystal polymer.
The prototype contains three sensors along with an RFID chip. Future devices for field use might contain a much larger number of sensors based on various nanomaterials – including carbon nanotubes, graphene and molybdenum disulfide – depending on the types of chemicals to be detected.
“In general, having an extensive sensing array is the best approach,” says Song. “For real-world applications, a variety of sensors can offer better functionality, because they can work together to produce a more detailed and reliable picture of the chemical environment.”
The RFID component in the GTRI device makes use of the 5.8 gigahertz (GHz) radio frequency. The GTRI component is believed to be the first RFID system that exploits this frequency.
“This is a relatively new band for a lot of passive RFID systems so we’ve been developing a full system from scratch because there has been nothing commercially available,” says Valenta. “We’ve developed our own tags, readers, antennas and everything from the ground up. By combining this technology with the chemical vapor sensors, we can extract data from the sensors and transmit it to enable detection of chemical vapors.”
The GTRI team is currently gearing up to design a very small, 5.8 GHz RFID component. After fabrication and testing, Valenta says that the chip could be manufactured inexpensively in large lots.
“It might take $400,000 to design and fabricate that first RFID chip, but all the subsequent copies might cost only a few pennies,” said Valenta, who is a Ph.D. candidate in the School of Electrical and Computer Engineering.
The GTRI team successfully tested its prototype sensing system in a demonstration designed to resemble an airport checkpoint. The sensor array detected the targeted chemical despite emersion in a complex chemical environment, and the RFID component was able to transmit sensor readings.