Newswise – ALBUQUERQUE, NM – Every over-the-counter medication bottle has a protective seal, usually a plastic wrap or foam layer or both. These seals provide signs of attempted manipulation. In parallel, the International Atomic Energy Agency relies on tamper detection devices to ensure it knows whether containers containing nuclear material have been opened or tampered with.

However, the IAEA fears that its devices could be bypassed and repaired or counterfeited, just as a medicine bottle could be opened by a bad guy and the tamper-evident seals carefully reattached. A possible solution? Engineers at Sandia National Laboratories have developed a groundbreaking prototype using “blood-crushing” materials. Your innovation not only detects manipulation; The new device boldly displays the evidence, like battle scars.

“Our first idea was to create a ‘bleeding’ material that was extremely obvious that it had been tampered with,” said Heidi Smartt, an electrical engineer and project manager at Sandia. “Then we made a new device from these materials where the harm is obvious to people. No one has ever developed such a concept for international nuclear security measures.”

Using commercially available colored water beads, a color-changing chemical reaction, and 3D-printed casings, the team created puck-shaped devices that turn dark brown when damaged or the wire loop threaded through them is pulled out.

The important part of the color-changing solution is a chemical called L-DOPA, which the body uses to make several vital neurotransmitters. This chemical can react with oxygen to form melanin, the brown chemical that gives human skin, hair and eyes their color.

The research team examined several other color-changing solutions before determining that the melanin-producing reaction, similar to the reaction caused by tanning, was the most practical, said Cody Corbin, a materials chemist from Sandia. “It has worked wonderfully since then.”

If someone drills a small hole in the device or tries to pull out the embedded wires, oxygen will enter. Inside, the oxygen reacts with the color-changing solution near the damage, turning it brown. Over time, more oxygen penetrates and the “bruise” grows.

The Sandia prototype devices are about the size of a stack of seven U.S. half-dollar coins, the same size as the metal cup seals the agency has used since the 1960s. The IAEA relies on tamper detection devices looped around the openings of cabinets containing vital monitoring equipment. The devices are also placed at the openings of spent nuclear fuel containers to visualize possible discharge.

However, IAEA inspectors must carefully examine these devices and their wire loops, looking for strange markings, color differences and other signs of tampering. This inspection is time-consuming and subject to human error. The purpose of the Sandia prototype is to reduce the time and subjectivity of such inspections.

To make the filling for the prototype devices, Corbin’s team adds a little water to a mix of clear and colored water beads until they’re slushy, he said. Then they mix the pearls until they are small pieces but no longer a fine powder. Once dry, they transfer the parts to a laboratory device called a glovebox.

The glove compartment contains several pairs of thick rubber gloves, allowing researchers to conduct experiments in an oxygen-free environment. Once in the glove compartment, the bead pieces are soaked in the color-changing solution and then a researcher pours the mixture into 3D printed cases and seals them. After closing, the cases can be removed.

“The other side of the tampering report is making sure you have unique identification to ensure that the devices cannot be easily counterfeited and replaced,” Corbin said. “The pearl colors ensure protection against counterfeiting. If someone wanted to recreate a puck, they would have to have every single red, blue and green spot in the same place.”

The team is currently testing dozens of pucks in a variety of different conditions that mimic different environments in which they might be used, Smartt said. This includes testing at temperatures from -22 to 150 degrees Fahrenheit and under intense UV light to age the materials more quickly, up to the equivalent of three years.

Last year, the team filed a patent for the color-changing material and recently filed a patent extension for the tamper indicator device itself. The team may also seek additional federal funding to test the devices locally and potentially seek corporate partners to license and commercialize the technology. As part of another ongoing project, the team has also made entire cases with tamper indicators out of the color-changing material.

“Since we began working on these materials, we have found that this is really valuable for any industry that is concerned about tampering with their packaging,” Smartt said. “I think we can really add value in this visually obvious aspect of our devices; this is a completely new thing. There are many other uses for these loop seals.”

Research into crushed materials was funded by Sandia Laboratory-driven research and development program. Further development and prototyping of the device was funded by the National Nuclear Security Administration Office of Nuclear Nonproliferation Defense.


Sandia National Laboratories is a multi-mission laboratory operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration. Sandia Labs has major research and development responsibilities in nuclear deterrence, global security, defense, energy technologies and economic competitiveness and has principal locations in Albuquerque, New Mexico and Livermore, California.

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