By Josh Perry, Editor
[email protected]

Researchers from the Skolkovo Institute of Science and Technology (Skoltech) in Moscow, Russia and the Massachusetts Institute of Technology (MIT) in Cambridge, Mass. have developed a new method for creating highly-transparent, electrically conductive, stretchable hydrogels with single-walled carbon nanotubes (SWCNT) that can be used in numerous applications.

SWCNT/hydrogel-based patterned circuit pictured in three ways: attached to human skin, relaxed, and stretched by 50 percent. (Skoltech)

According to a report from Skoltech, the scientists used a simplified, one-step technique to place SWCNT on hydrogels, which avoids issues such as SWCNT agglomeration and the removal of surfactants.

“The researchers demonstrated two ways of fabricating SWCNT/hydrogel structures,” the report explained. “The first approach is based on a simple transfer of the SWCNTs from a filter to the as-prepared hydrogel surface, while the second one is based on the pre-stretching of the hydrogel before the SWCNT film is deposited.”

The first approach produced hydrogels that remained stable after more than 5,000 stretching/releasing cycles, while the second approach produced hydrogels with high conductivity at high strain and that were highly transparent.

This fabrication approach could lead to large-area electronic circuits, wearable devices, biomedical devices and other applications.

The research was recently published in Applied Materials and Interfaces. The abstract stated:

“Electrically conductive hydrogels (ECHs) are attracting much interest in the field of biomaterials science because of their unique properties. However, effective incorporation and dispersion of conductive materials in the matrices of polymeric hydrogels for improved conductivity remains a great challenge.

“Here, we demonstrate highly transparent, electrically conductive, stretchable tough hydrogels modified by single-walled carbon nanotubes (SWCNTs). Two different approaches for the fabrication of SWCNT/hydrogel structures are examined: a simple SWCNT film transfer onto the as-prepared hydrogel and the film deposition onto the pre-stretched hydrogel.

“Functionality of our method is confirmed by scanning electron microscopy along with optical and electrical measurements of our structures while subjecting them to different strains. Since the hydrogel-based structures are intrinsically soft, stretchable, wet, and sticky, they conform well to a human skin.

“We demonstrate applications of our material as skin-like passive electrodes and active finger-mounted joint motion sensors. Our technique shows promise to accelerate the development of biointegrated wearable electronics.”