Power on the Go

Imagine soldiers being able to power electronic devices and sensors as they patrol the field for hours, without carrying bulky batteries or cords.

That is the goal of a team of researchers at the Harnessing Emerging Research Opportunities to Empower Soldiers (HEROES) program, a joint effort between UMass Lowell and the U.S. Army DEVCOM Soldier Center in Natick, Massachusetts. The HEROES program, which is based at the university, is developing advanced technologies to help improve the soldiers’ combat protection, sustainability and effectiveness.

“Our project aims to create robust and reliable power-harvesting fabrics that can be worn by soldiers over their uniforms. These fabrics are capable of converting energy from sunlight into electricity for charging small devices such as sensors, which require low amounts of power,” says Plastics Engineering Prof. Ramaswamy Nagarajan, co-director of HEROES and the UML Fabric Discovery Center.

He notes that the power requirements of soldiers have increased exponentially over the years, but the ability to generate power using portable and flexible devices has not kept pace.

“The fabrics we are developing are flexible, breathable and can be easily integrated onto the soldier’s garment or backpack,” Nagarajan says.

In the future, the technology may be used to charge power-hungry gadgets carried by civilians, such as smartwatches, smartphones and headphones.

“If we can prolong their useful battery life utilizing power-harvesting fabrics, that would go a long way in reducing the need for frequent recharging,” Nagarajan says. “For soldiers who are deployed, access to a reliable power source is a crucial factor. Reducing the need to recharge batteries will significantly improve the soldiers’ efficiency.” 

Access to a reliable power source is a crucial factor. Reducing the need to recharge batteries will significantly improve the soldiers’ efficiency.” -Prof. Ramaswamy Nagarajan

Aside from Nagarajan, other members of the research team include Physics Prof. Jayant Kumar, Senior Technical Program Manager Claire Lepont and DEVCOM Soldier Center Research Chemist and HEROES Co-Director Ravi Mosurkal, as well as former students Madison Reed ’21, Peter Steeves ’21, Siddhant Iyer ’22 and Vedant Raheja ’21 and postdoctoral researcher Anna Maria Routsi.

“Nowadays, the load that the soldiers carry keeps going up, and they have many devices that require power in the field,” says Mosurkal. “So, if they have this self-sufficient, energy-harvesting system, they can continuously charge their batteries and have power available all the time.”

“The technology can work not only with sunlight, but also with artificial light,” Lepont adds.

According to Nagarajan, the unique aspect of the project is the fabrication of the fabric’s solar yarn, also called organic photovoltaic (OPV) fiber. It starts with an ultrasmooth stainless steel wire that is coated with various organic photoactive and electroactive layers to harness energy from photons. A smooth secondary metal wire—the other electrode of the solar cell—is wrapped around the coated wire, and the two are cladded in a transparent, protective thermoset material that has been cured with ultraviolet light. The fiber is then woven on a conventional textile loom to produce the power-harvesting fabric.

“The last step is connecting the solar yarn to bus bars—solid metallic strips that are used to distribute electric power and create a fully functional device,” says Nagarajan.

The custom fabrication of the wire-coating line used to create the OPV fiber is done at the Fabric Discovery Center, and the project was supported by the Massachusetts Manufacturing Innovation Initiative (M2I2).

Thanks to grants totaling nearly $1.2 million from the Army, HEROES researchers are now focusing on increasing the fiber’s energy efficiency by using a flat wire for the secondary electrode, because it offers better contact with the coated wire than having two cylinder-shaped wires.

The team is also working to improve the oxygen- and moisture-barrier properties of the cladding material, as well as exploring new methods for connecting the OPV fibers, including the use of electronically conductive Velcro and ultrasonic bonding. The latter research is funded by the Advanced Functional Fabrics of America (AFFOA) in collaboration with UML Mechanical Engineering Assoc. Prof. Scott Stapleton and DCS Corp. Researchers are also investigating ZTACH® ACE, a patented conductive epoxy bonding system from SunRay Scientific in Eatontown, New Jersey, and this research is also funded by AFFOA.

“Finally, we are working on integrating the OPV fabric with flexible batteries,” says Nagarajan. This step is being undertaken in collaboration with UML Mechanical Engineering Assoc. Prof. Ertan Agar.

The team’s external collaborators include Unifire Inc., based in Spokane, Washington, which created fabric used by wildland firefighters and first responders through funding from the U.S. Department of Homeland Security, and Nano-C in Westwood, Massachusetts, which supplied the chemical solutions used to create the steel wires’ photoactive and electroactive organic layers through a subcontract from the Office of Naval Research.

“Our strategic partnership with HEROES has allowed our interdisciplinary scientists and engineers to utilize world-class capabilities at UMass Lowell, as well as the university’s faculty expertise,” says Craig Rettie, director of research and technology integration at DEVCOM Soldier Center.

“This partnership helps advance our science and technology knowledge and, ultimately, develop new capabilities for our nation’s soldiers,” he says.

“Our scientists and engineers work synergistically with UML faculty, students, staff and industry partners to develop novel and effective solutions to the challenges facing our men and women in uniform,” says Robb Wilcox, DEVCOM SC’s chief research officer.

According to Wilcox, this unique collaboration has enabled innovative research and new capabilities in technologies related to smart textiles, smart material sensing and wearable electronics, to name a few.

Mosurkal notes that this cooperative agreement can be used as a model in catalyzing future partnerships with DEVCOM SC throughout the country.

“The HEROES initiative will continue to grow by focusing on technology transfer and product development for modernizing the soldier’s protection, effectiveness and sustainment,” he says.

Nagarajan says that over the past decade, the HEROES team has worked with more than 70 faculty members from the university’s five colleges, providing opportunities to more than 100 students to dream, conceptualize, prototype and test new technologies for empowering soldiers.

“In collaboration with industry and DEVCOM SC, we are transitioning these technologies into products and services that can truly benefit our soldiers,” he says.