Crocodiles' Wave Sensors Inspire a New Stretchable, Wearable Pressure-Sensing Electronic Skin

A team of scientists from the Pohang University of Science and Technology (POSTECH) and the University of Ulsan have developed a pressure-sensing electronic skin which works even when stretched in any and all directions — inspired by how crocodiles sense waves on water.

"This is a wearable pressure sensor that effectively detects pressure even when under tensile strain," says Kilwon Cho, professor at POSTECH and team lead on the project. "It could be used for diverse applications such as pressure sensors of prosthetics, electronic skin of soft robotics, VR [Virtual Reality], AR [Augmented Reality], and human-machine interfaces."

The novel electronic skin was designed based on observations of crocodile skin — in particular, "sensory bumps" located beneath its wrinkled skin and connected via natural "hinges" which allow the crocodile to move in any direction without triggering the sensors. Regardless of how stretched or relaxed the skin of the crocodile is at any given time, the sensory bumps still pick up the feeling of waves on water — letting the crocodile know where its prey can be found.

The synthetic crocodile skin developed by the team mimics both the domed sensory organs and the wrinkled outer layers, filled with a combination of short or long nanowires. Unlike other electronic skin designs, the result is a sensory layer which can stretch freely in any direction yet still retain its pressure sensitivity — even when pulled up to double its length in a single direction or up to half its size again in two directions.

To demonstrate the skin's capabilities, the team mounted it on a plastic crocodile and submerged the resulting test system in water — showing that, like the predator which inspired its creation, the electronic croc is able to pick up the movement of even small waves.

The team's work has been published in the journal Small under closed-access terms.