The electronic skin is transparent, stretchable, touch-sensitive, self-healing in aquatic environments and could be used in everything from water-resistant touchscreens to aquatic soft robots, claim the team from the National University of Singapore (NUS).
Assistant Professor Benjamin Tee and his team from the Department of Materials Science and Engineering at the NUS Faculty of Engineering developed the material, along with collaborators from Tsinghua University and the University of California Riverside.
The researchers spent just over a year developing the material, and its invention was first reported in Nature Electronics in February 2019.
Asst Prof Tee has been working on electronic skins for many years and was part of the team that developed the first ever self-healing electronic skin sensors in 2012.
“One of the challenges with many self-healing materials today is that they are not transparent and they do not work efficiently when wet,” he said. “These drawbacks make them less useful for electronic applications such as touchscreens which often need to be used in wet weather conditions. So, we wondered how we could make an artificial material that could mimic the water-resistant nature of jellyfishes and yet also be touch sensitive.”
They did this by creating a gel consisting of a fluorocarbon-based polymer with a fluorine-rich ionic liquid. When combined, the polymer network interacts with the ionic liquid via highly reversible ion–dipole interactions, which allows it to self-heal.
Tee said: “Most conductive polymer gels such as hydrogels would swell when submerged in water or dry out over time in air. What makes our material different is that it can retain its shape in both wet and dry surroundings. It works well in sea water and even in acidic or alkaline environments.”
According to NUS, the electronic skin is created by printing the novel material into electronic circuits. As a soft and stretchable material, its electrical properties change when being touched, pressed or strained. “We can then measure this change and convert it into readable electrical signals to create a vast array of different sensor applications,” said Tee.
“The 3D printability of our material also shows potential in creating fully transparent circuit boards that could be used in robotic applications. We hope that this material can be used to develop various applications in emerging types of soft robots,” said Tee.
Soft robots, and soft electronics in general, aim to mimic biological tissues to make them more mechanically compliant for human-machine interactions. In addition to conventional soft robot applications, this novel material’s waterproof technology enables the design of amphibious robots and water-resistant electronics.
Tee and his team are hoping to explore further possibilities of this material.
“Currently, we are making use of the comprehensive properties of the material to make novel optoelectronic devices, which could be utilised in many new human–machine communication interfaces,” he said.
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