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Manufacturing Bits: Nov. 13

Power beams; wall-penetrating radar; stretchable conductors.

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Power beams
The U.S. Naval Research Laboratory and PowerLight Technologies have demonstrated the ability to transmit energy using a long-range, free-space power beaming system.

The system is being developed as part of the Power Transmitted Over Laser (PTROL) project. The system consists of two 13-foot-high towers. One tower consists of 2-kilowatt laser transmitter. The other tower consist of a receiver using photovoltaics.

In the demonstration, a laser beamed 400 watts of power from one tower to another at a distance of 325 meters. The laser transmission, which was invisible, created enough power to run various systems during the demo, such as lights, PCs and a coffeemaker.

Power beam technology has been in R&D for years. The technology has various applications, such as sending power via a beam to remote locations. It could be used to power unmanned aerial vehicles (UAVs). Power beaming could also transmit power from solar satellites in space to the ground.

There are several challenges with the technology, such as the risk of exposure to hazardous power densities. Another issue is the effects of snow, rain and other types of weather.

PowerLight, a developer of power beaming technology and the hardware provider for the PTROL project, has devised a system with integrated safety features. During the test, no one was wearing laser safety goggles or other gear.

The PTROL project, which is in its second phase, is being spearheaded by PowerLight and the U.S. Naval Research Laboratory. “Power beaming, the concept, has been around for decades and there’ve been laboratory demonstrations, but this is really a first and a new technology that’s getting fielded,” said Tom Nugent, chief technology officer of PowerLight Technologies.

“If we could capture the boundless sunlight in space, where it’s brighter than anywhere on Earth, (we could) send it to places that are difficult and expensive to get energy to today,” said Paul Jaffe, an electronics engineer with the U.S. Naval Research Laboratory. “If we can do that in an effective way and do for energy what GPS has done for navigation, it would truly be revolutionary.”

Wall-penetrating radar
The U.S. Army has announced the winner of the second Expeditionary Technology Search competition, known as xTechSearch.

Lumineye, a U.S.-based startup, took the top prize of $250,000 for their wall-penetrating radar system. The technology could help soldiers and first responders identify people and potential threats through walls.

The company has developed Lux, a compact, lightweight through-wall sensor designed for firefighters, law enforcement, and search and rescue teams.

The xTechSearch competition is an effort by the Army and the small-business sector to engage with each other and develop new technologies. “The xTechSearch competition helped us learn a lot along the way,” said Corbin Hennen, chief executive and co-founder of Lumineye, with Megan Lacy, co-founder and chief design officer. “Getting the first bit of funding was important. The funding from phase three was the first significant funding we’ve received. It showed us true customer support and that the Army was really interested in us. It also allowed us to participate in the Y Combinator accelerator program.”

Stretchable conductors
The Air Force Research Laboratory (AFRL) has developed a stretchable conductor technology for use in next-generation wearable electronics and other systems.

The technology, called Polymerized Liquid Metal Networks, can automatically change their structures. Yet, the liquid metal maintains its conductivity in response to strain.

Generally, conductive materials can change their properties, but the electrical conductivity decreases as they stretch, according to the AFRL. The resistance also increases as the properties change.

To solve the problem, researchers from AFRL developed room‐temperature liquid metals, such as gallium alloys. In the liquid metal, particles are enclosed in a shell. Each particle is attached to the next one via a polymerization process.

“Core–shell particles of liquid metal with surface‐bound acrylate ligands are synthesized and polymerized together to create cross‐linked particle networks comprising >99.9% liquid metal by weight,” according to the AFRL in Advanced Materials, a journal. “When stretched, particles within these polymerized liquid metal networks (Poly‐LMNs) rupture and release their liquid metal payload, resulting in a rapid 108‐fold increase in the network’s conductivity.”

This in turn allows the materials to become conductive and stretchable. There is no detection of fatigue after 10,000 cycles.

The technology could one day be used for various applications, such as soft robotics, e‐skin and wearable technologies. “The discovery of Polymerized Liquid Metal Networks is ideal for stretchable power delivery, sensing and circuitry,” said Capt. Carl Thrasher, research chemist within the Materials and Manufacturing Directorate at AFRL. “Human interfacing systems will be able to operate continuously, weigh less, and deliver more power with this technology.”



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