Researchers at ETH Zurich, Switzerland, a leading technology university, say they have developed electronic components that are so thin and flexible they can even be wrapped around a single hair without damaging the electronics. This may open up new possibilities for ultra-thin, transparent sensors, including to create smart contact lenses, which could be used to measure intraocular pressure to test for glaucoma, among other uses. The new thin-film transistors adhere to a wide range of surfaces and adapt perfectly, they say.
The scientists are researching flexible electronic components, such as transistors and sensors, which could be woven into textiles or applied to the skin in order to make objects ‘smart’, and to develop unobtrusive, comfortable sensors that can monitor various body functions.
They fabricated thin-film components mounted onto a membrane of parylene film, which has a maximum thickness of 0.001 mm, making it 50 times thinner than a human hair. In subsequent steps, they used standardized methods to build transistors and sensors from semiconductor materials, such as indium gallium zinc oxide, and conductors, such as gold. The researchers then released the parylene film with its attached electronic components from the wafer.
An electronic component fabricated in this way is extremely flexible, adaptable, and even transparent. The researchers confirmed the theoretically determined bending radius of 50 micrometers during experiments in which they placed the electronic membrane on human hair and found that the membrane wrapped itself around the hair with perfect conformability. The transistors, which are less flexible than the substrate due to the ceramic materials used in their construction, still worked perfectly despite the strong bend.