Dr Anusha Withana

People living with profound visual impairments must rely on sensory substitution – using other senses in place of sight to understand the world.

Tactile information is particularly important in this regard, but the majority of tactile interfaces are unpopular because they tend to be bulky and have limited bandwidth due to mechanical impedance.

To address this, University of Sydney Lecturer Dr Anusha Withana lead a project called Tacttoo, which involved the creation of a thin, flexible and disposable electronic tattoo that could generate a high-resolution tactile sensation on the skin.

Unlike mechanical actuators, Tacttoo directly interfaces with nerve fibres to generate an electro-tactile sensation. And at under 35 μm in thickness, it is thinner than any other tactile interface devised.

Tacttoo works by combining multiple functional inks — including stretchable PEDOT-PSS polymer and rigid Ag/AgCl — with different mechanical properties to create a thin and stretchable structure that can be used as an electronic tattoo.

Withana’s team also engineered tiny spring mechanisms so that Tacttoo conforms with microstructures of the skin surface.

As a result, users cannot feel it on their skin, meaning it works as an interface that can be felt through. The spring structures can withstand the stresses of a normal eight-hour working day, while the Tacttoo is worn on a user’s fingertip in an office environment.

That means it can be used as a braille replacement for visually impaired people to explore graphics such as maps, online images and videos, which ensures visually impaired people will no longer have to rely on abstract and insufficient details conveyed by text-to-speech technology.

Graphical information can be critically important when it comes to education, where visually impaired students’ needs to learn geometric shapes, spatial relationships, dimensions and graphs. Therefore, creating effective, affordable and real-time visual to tactile translation methods addresses a significant problem in the society.

The project was funded by the European Union as part of a European Research Council project on interactive skin.

Judges’ comments:

“A fascinating project showing a range of engineering skills, including design and fabrication challenges. This product addresses a specific gap in the market and the academic literature.”