Researchers at the Swiss Federal Institute of Technology in Zurich (ETH Zurich) have created clear, flexible electronic circuitry that is so thin it can sit upon the surface of a contact lens, or be wrapped around a human hair. The research, led by Dr. Giovanni Salvatore, could ultimately be used for implantable medical devices. One such potential application suggested by the team is a “smart contact lens” that could monitor intraocular pressure for glaucoma patients.

In order to create the circuits, the layers are deposited using e-beam evaporation, atomic layer deposition, spin coating and radio frequency sputtering. The structuring is created using ultraviolet (UV) lithography and etching. The circuits are created on a substance called parylene, an insulator that is traditionally used as a protective coating for electronic devices and components.

“Parylene is a suitable material because it is able to withstand quite high temperatures (150 degrees Celsius [302ºF] in our process) and it is also not attacked by the etchands and solvents used during the fabrication process,” explains Niko Münzenrieder, one of the authors of the research. “Furthermore, it is transparent and bio-compatible, which is beneficial for different applications like the smart contact lens. Of course, it is also flexible.”

The research team envisages using a wireless power source for the contact lens, such as a magnetic field. Harvesting solar or kinetic energy on the parylene surface are also potential approaches that the team have considered. Besides the smart contact lens, Münzenrieder suggests that the technology could be used as a smart textile for sports or in a hospital to monitor physiological factors like body temperature.

Münzenrieder says that the team does not expect the technology to be commercially available in less than five years, but the future of its research will be no less compelling.

“The energy supply of the flexible circuits is definitely a hot topic,” he explains. “At the same time we are also working on more complex circuits, and sensors to monitor, e.g. humidity or different gases. Besides this we are also exploring the possibility of integrating the membrane with other objects like textiles and elastic materials to realize something like a smart skin for robots or prostheses.”

The research has been published in the journal Nature Communications.

Source: ETH Zurich

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