An ingenious way of creating therapeutic heat for applying to injuries in a light, flexible design has been developed by Korean scientists from the Center for Nanoparticle Research, Institute for Basic Science (IBS).

Other researchers have designed similar devices previously, but none were able to come up with something that didn’t rely on exotic materials or a complex fabrication process, which would drive up the price tags.

The team at IBS steered away from materials like carbon nanotubes and gold, taking a more utilitarian option for their build material, with thin slivers of silver nanowires.

Silver nanowires are miniscule, averaging around 150 nm in diameter and 30 μm in length (a human hair ranges from 17 to 181 µm). The nanowires were blended into a liquid elastic material which is both soft and stretchy when dry.

To be certain the material stays tight on the wound area while heating, the team designed a 2-D interlocking coil pattern for the mesh structure.

To fabricate the mesh, a liquid mixture was poured into a shaped mold. The silver-elastic mesh was sandwiched between a top and bottom layer of soft, thin insulation.

Material flexibility testing on knee and wrist joints showed the mesh heated while deformed and under stress on knee and wrist joints. It is lightweight, breathable and generates heat over the entire surface area of the material.

Why the need for a new heat therapy device?

A hot water bottle used for treating muscle soreness feels good, but it will inevitably cool down while in use.

And commercially available electric heating pads are sufficient for applying heat to an injured area but their cords need to be attached to an outlet to work.

But the mesh maintains a constant temperature instead of cooling down during use and is battery powered so it doesn’t need an outlet.

Suji Choi, Jinkyung Park, Wonji Hyun, Jangwon Kim, Jaemin Kim, Young Bum Lee, Changyeong Song, Hye Jin Hwang, Ji Hoon Kim, Taeghwan Hyeon, and Dae-Hyeong Kim, (2015) “Stretchable Heater Using Ligand-Exchanged Silver Nanowire Nanocomposite for Wearable Articular ThermotherapyAmerican Chemical Society, DOI: 10.1021/acsnano.5b02790

Photo: Korean Institute for Basic Science

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