The wearable thermal camouflage device is embedded in an armband and blends with the ambient temperature.

« This wearable device camouflages its wearer no matter the weather

Newswise — Researchers at the University of California San Diego developed a wearable technology that can hide its wearer from heat-detecting sensors such as night vision goggles, even when the ambient temperature changes–a feat that current state of the art technology cannot match.  The technology can adapt to temperature changes in just a few minutes, while keeping the wearer comfortable.

The device, which is at the proof-of-concept stage, has a surface that quickly cools down or heats up to match ambient temperatures, camouflaging the wearer’s body heat. The surface can go from 10 to 38 degrees Celsius (50 to 100.5 degrees Fahrenheit) in less than a minute. Meanwhile, the inside remains at the same temperature as human skin, making it comfortable for the wearer. The wireless device can be embedded into fabric, such as an armband. A more advanced version could be worn as a jacket.

To build the device, the team turned to a phase-changing material that’s similar to wax but with more complex properties. The melting point of the material is 30 degrees Celsius (roughly 86 degrees F), the same temperature as the surface temperature of human skin. If the temperature on the outside of the device is higher than that, the material will melt and stabilize, insulating the wearer; if colder, it will slowly solidify, still acting as an insulating layer.

The team, led by UC San Diego mechanical and aerospace engineering professor Renkun Chen, detailed their work in a recent issue of the journal

Advanced Functional Materials

.

At the technology’s core are materials that can create heating or cooling effects when the ambient temperature changes, and flexible electronics that can be embedded into clothing. The outside layer of the device is driven by a technology that Chen and colleagues detailed in a paper in

Science Advances

in May 2019. It is made of thermoelectric alloys—materials that use electricity to create a temperature difference—sandwiched between stretchy elastomer sheets. It is powered by a battery and controlled by a wireless circuit board. The device physically cools or heats to a temperature that the wearer chooses.

Current state of the art heat camouflage technology consists of a surface coating that changes how much heat clothing emits at the surface. The coating absorbs the heat from the wearer’s body and reflects only enough energy to match the ambient temperature. However, the coating only works at a predetermined temperature. If the ambient temperature rises or falls, it no longer works.

The researchers’ biggest challenge now is to scale up the technology. Their goal is to create a jacket with the technology built-in, but under current conditions, the garment would weigh 2 kilograms (about 4.5 lbs.), be about 5 millimeters thick and only function for one hour. The team will be looking to find lighter, thinner materials so the garment could weigh two or three times less.

The work was supported by the Advanced Research Project Agency and by a UC San Diego start up grant. It work was performed in part at the San Diego Nanotechnology Infrastructure (SDNI) at UC San Diego, a member of the National Nanotechnology Coordinated Infrastructure, which is supported by the National Science Foundation.

An Adaptive and Wearable Thermal Camouflage Device

Sahngki Hong and Renkun Chen, University of California San Diego

Sunmi Shin  National University of Singapore

Robbers Who Targeted Elderly Sentenced

In 2018, a 74-year-old Tennessee woman was attacked in her home by a pair of robbers who ransacked her house and stole her sense of safety.

Days later, a 72-year-old Tennessee man with dementia was attacked outside his home by the same assailants. They forced him inside and threw him down a stairwell after robbing him of a few possessions. Among the items stolen was a bomber jacket from the man’s service in Vietnam. It was an irreplaceable keepsake that investigators never found.

In all, Joshua Small and his girlfriend, Joni Johnson, robbed—and in some cases violently assaulted—seven senior citizens in West Virginia, Virginia, and Tennessee during a short period in the summer of 2018. In several cases, they subdued their victims by punching or hitting them and then tying them up while they ransacked their homes. The robbers held some of their victims at gunpoint or threatened them with guns.

The incidents shook the small, quiet towns where they took place.

“One victim’s son told us, ‘This is a small town. Everyone here knows me or my dad,’” said Special Agent Wesley Leatham, who investigated this case out of the FBI’s Knoxville Field Office along with FBI Task Force Officer Mark Webber of the Knox County Sheriff’s Department. “It really caused a lot of worry and concern in these communities.”

A break in the case came when a tipster saw a couple driving a rental car that matched the description of the robbers’ car and told local police. Pawn shop employees also confirmed that Small had been seen pawning stolen jewelry and other items.

Investigators found overwhelming evidence against the couple once they were identified, including incriminating evidence on their cell phones. Several victims also identified Johnson and Small based on photos.

The couple lived in West Virginia, and they used Small’s employer, a family paving business, to find some of their elderly victims. In other cases, investigators aren’t certain how the robbers targeted their victims, but they were all in their 70s, 80s, or 90s.

“Everyone really wanted to see justice for these victims, especially given their ages and the level of violence they suffered.”

Wesley Leatham, special agent, FBI Knoxville

With multiple sheriffs’ offices involved, the FBI played a key coordinating role. The Bureau also brought resources to the case, including the ability to press federal charges.

“We had great local partners in this case,” Leatham said. “Everybody came together with outstanding coordination. Everyone really wanted to see justice for these victims, especially given their ages and the level of violence they suffered.”

In July 2019, the couple was convicted of kidnapping charges. In January, Small was sentenced to 30 years in federal prison, and Johnson was sentenced to 25 years.

Investigators hope the outcome brought some closure to the victims and communities that were traumatized. One victim died before the trial and some others were unable to travel to it, but their relatives gave powerful impact statements.

“We’ve heard from the victims’ families since then that this has destroyed their sense of safety. They’re constantly checking the door to make sure it’s locked. Visitors have to call before they come over,” Leatham said. “It’s really had a lasting effect on a lot of people.”

Resources

Joshua Small and Joni Amber Johnson Sentenced for Kidnapping Elderly Victims