Japanese technology firm SK-Electronics has developed a passive ultrahigh-frequency (UHF) RFID tag that is less than 0.5 millimeters by 0.5 millimeters (0.02 inch by 0.02 inch) in size—small enough to fit on the back on an ant. For SK-Electronics, the fact that the tag can effectively transmit data (albeit with a maximum read range of about 2 millimeters, much shorter than the typical range of larger tags) means that the new Fine Tag, as it’s called, could be applied to small products moving through the supply chain, for example, or requiring anti-counterfeit verification at a store. However, the company has chosen a uniquely challenging use case to put the tag to the test first: tracking the movements of individual ants. While the ant research project continues, SK-Electronics has begun marketing the Fine Tag for commercial use. According to Ichii Hirotaka, SK-Electronics’ associate director, the company is now offering samples of the Fine Tag in small quantities, but expects to be able to fill large orders by the end of 2015.
SK-Electronics is primarily a photomask manufacturing company for LCD panels, which spun off from Kyoto printing company Shashin-Kagaku in 2001. Photomasks are plates used to restrict the transmission of light to a defined pattern in LCD panels. However, the firm recently began applying its engineering skills to developing a new RFID tag. For the past three years, it has been developing a product that would be smaller than other existing tags on the market. Such a tag could be used for tracking tiny items, such as surgical tools, pharmaceuticals or other medical supplies; for brand protection of small, high-value products; and for the management of small animals.
“We expect that the small-tag market will be growing,” Hirotaka says, explaining why he feels RFID tag production may become central to SK-Electronics’ offerings. Ichii declines to reveal exactly how the new tag is developed, or which IC is built into it, but says it complies with the EPC Gen 2 standard, and that any conventional RFID reader device would be able to read or write to the tag. Due to its small antenna size, the Fine Tag can be interrogated at a maximum distance of 1 to 2 millimeters (0.04 inch to 0.08 inch). The Fine Tag, which comes with 512 bits of memory, can operate in the presence of liquids and metals, though environments with a great deal of liquid or metal may require a supplemental tag antenna or a customized version of the Fine Tag made with an antenna for the specific application.
To test the new tag, the company sought a real-world challenge, which it found in ant research at the Kyoto Institute of Technology (KIT). SK-Electronics supplied KIT with tags, a reader with a very small antenna measuring about 1 centimeter (0.4 inch) in diameter, and software to interpret the read tag data. Researchers at KIT then included Hiroshima University in the pilot.
Researchers studying ant behavior face one significant challenge: The insects can be difficult to identify and track each individual ant, and thereby understand its role within its community, as larger animals are studied, often with identifiers attached to them.
Toshiharu Akino—who works at KIT’s Center for Bioresource Field Science and is a KIT associate professor of animal communications, entomology and chemical biology—has spent the last year with his fellow researchers monitoring the behavior of carpenter ants, by saddling each one with an SK-Electronics UHF RFID tag (adhesively attached to its back), and installing reader antennas (also built by SK-Electronics) at the entrance to a foraging area, as well as at the nest’s opening, each wired to a reader installed near the entrance. Once Akino began working with the technology, Hiraku Nishimori, a professor at Hiroshima University’s graduate school of science department of mathematical and life sciences, joined the project in order to evaluate the data resulting from the early testing.
“We are seeking possibilities of the small-objects tracing with this small tag,” Ichii says. “We believe if this was effective for the ant-based research, it will also be useful for other areas.” The researchers began installing readers and attaching the tags to ants in early 2013, and expect to continue the program until May of this year.
KIT uses the tags to study behavioral interactions among family members within an ant colony. “To sustain the ant society, there are various types of tasks that require workers’ labor,” Akino explains. One task is to forage outside of the nest, which requires a certain level of skill and experience. Thus, the scientists presume, foraging work tends to be undertaken by older workers within a colony. Once researchers are able to identify and describe the task and age of each ant worker, they can then determine whether individual ant workers can discriminate each other based on the tasks they carry out. “Our preliminary observation suggests that the ant workers have such an ability,” he says. The team’s aims are to clarify whether ants can discern one worker from another—and, if so, how—and to ascertain each ant’s tasks.
The use of RFID, Akino says, “is quite valuable because it is difficult to obtain such behavioral data in eusocial [socially organized] insects.”
Each ant—which measures 7 millimeters to 12 millimeters (0.3 inch to 0.5 inch) in length—carries the tag past two reader antennas installed at the entrance of the nest chamber and that of the foraging area. The researchers had to make some preliminary adjustments, Akino notes. To improve read rates, they altered the height of the tunnel so that readers installed on the ceiling could better read the tags as the ants passed.
Each tag was encoded with a unique identifier, and was then applied to an ant as it came out of the pupae stage. “A total of 30 to 40 workers were tagged,” Akino says. Separately, the researchers also tagged approximately 30 to 40 elder workers.
The Hiroshima University research team, headed by Nishimori, is currently collecting and analyzing RFID data. The automatic tracking system provided by RFID, he says, “enhances the chance to take the high-quality and long-duration big data for small ants.”