New Supercapacitator Design Could Power Wearable Medical Devices
By Joel Lindsey
An international team of researchers has created a new fiber-like energy storage device that could be woven into articles of clothing and used to power wearable medical devices, especially those worn by patients as part of in-home treatments.
“Because [the fibers] remain flexible and structurally consistent over their length, the fibers can also be woven into a crossing pattern into clothing for wearable devices in smart textiles,” Yuan Chen, professor of chemical engineering at Nanyang Technological University (NTU) and leader of the research team, said in a press release published recently by Case Western Reserve University.
The device — a newly designed supercapacitator — is the result of work by scientists and engineers at NTU in Singapore, Tsinghua University in China, and Case Western in the United States. Researchers involved in the project report that the new supercapacitator could have a higher power storage capacity, when measured by volume, than any other “carbon-based microscale supercapacitator” currently available, according to the press release.
“Most supercapacitators have high power density but low energy density, which means they can charge quickly and give a boost of power, but don’t last long,” said Liming Dai, a researcher from Case Western involved with the project. “Conversely, batteries have high energy density and low power density, which means they can last a long time, but don’t deliver a large amount of energy quickly.”
The research team’s new supercapacitator was designed as an attempt to bring together both high power density and high energy density into a single device.
According to the press release, the fiber-like supercapacitator is produced when a solution of acid-oxidized single-wall nanotubes, graphene oxide, and ethylenediamine is pumped through a flexible, narrow, and reinforced tube called a capillary column. It is then heated for six hours, and microthin sheets of graphene, along with aligned, single-walled carbon nanotubes, self-assemble into a porous matrix.
Because the entire structure is tightly packed in the capillary column, the final product takes on the shape of long and continuous fibers. Researchers have so far manufactured a supercapacitator fiber 50 meters long and report no limitations to the possible lengths these fibers could take.
Through a series of tests, the results of which have been published recently in the journal Nature Nanotechnology, researchers have found that the new fiber-like supercapacitator may be capable of maintaining high measures of power density, energy density, and cycle stability, even when the fibers are placed under physical stress.
“We have tested the fiber device for 10,000 charge/discharge cycles, and the device retains about 93 percent of its original performance, while conventional rechargeable batteries have a lifetime of less than 1,000 cycles,” said Dingshan Yu, a researcher from NTU involved with the project. “The fiber supercapacitator continues to work without performance loss, even after bending hundreds of times.”
The device’s ability to perform while being bent may allow it to be woven into clothing, where researchers claim it could help power wearable or portable medical devices. This characteristic could also allow the fiber supercapacitator to be used in other applications as well.