Two new developments in RFID research could pave the way for tags that are thinner, cheaper, and more versatile. Using new materials and cutting-edge laser fabrication, engineers at North Dakota State University have made RFID tags compatible with paper or metal, with applications ranging from banknotes to cargo containers.
The key to embedding ultra-thin RFID tags into paper is what’s called Laser Enabled Advanced Packaging. Instead of using the pick-and-place robotic methods generally employed with today’s larger tags, a laser pulse is used to insert the RFID circuitry into a substrate: in this case, paper. The force generated by this laser pulse is essential when dealing with chips that are so thin — 20 microns, less than most commercial RFID chips — in order to overcome the attractive forces that could hinder the pickup and placement with conventional methods. Static electricity, for example, can make the super-skinny chips stick to the robot, which impacts assembly speed and precision.
The speed and precision of this contactless method beats current manufacturing techniques, according to the researchers, and it also doesn’t result in bumps in the paper. An added benefit is that the chip’s silicon becomes flexible at such tiny scales, so it can bend if needed. The paper-embedded RFID tag still has a tiny antenna, which is first printed onto the paper before the laser etching. Another NDSU discovery has done away with the antenna altogether, overcoming the interference problems associated with tagging metals or containers filled with liquid.
The passive ultra-high frequency tags use the metal objects to which they are attached as antennas. This means that they can be thinner, because no spacer is required to isolate the tag from the metal surface to make it readable. In addition, the tag’s highly permeable material lets current flow into the integrated circuit. “RFID on metal” could be used to track assets from laptops to medical devices and oil barrels, and because they can be embedded in the metal itself, they can stay with an object from origin to end. While the creation of antenna-less RFID tags isn’t entirely new, the development marks another step towards realizing the internet of things.
Image via North Dakota State University Center for Nanoscale Science and Engineering