Electronic skin as flexible as crocodile skin – Zoo House News

The development of multi-sensing electronic skin is crucial for various fields including rehabilitation, healthcare, prosthetics and robotics. One of the key components of this technology are stretchable pressure sensors that can detect different types of touch and pressure. Recently, a joint research team from POSTECH and Ulsan University in Korea made a major breakthrough by successfully developing omnidirectional stretchable pressure sensors inspired by crocodile skin.

The team behind the research was led by Professor Kilwon Cho, Dr. Giwon Lee and Dr. Jonghyun Son from the Department of Chemical Engineering at POSTECH, together with a team led by Professor Seung Goo Lee from the Department of Chemistry at the University of Ulsan. Inspired by the unique sensory organ of crocodile skin, they developed pressure sensors with microdomes and wrinkled surfaces. The result was a pressure sensor that could be stretched in all directions.

Crocodiles, formidable predators that spend most of their time underwater, possess a remarkable ability to sense small waves and recognize the direction of their prey. This ability is made possible by an incredibly sophisticated and sensitive sensory organ located on their skin. The organ consists of hemispherical sensory protuberances arranged in a repeating pattern with wrinkled hinges between them. When the crocodile moves its body, the hinges deform, while the sensory part remains unaffected by mechanical deformations, allowing the crocodile to retain an exceptional level of sensitivity to external stimuli when swimming or hunting underwater.

The research team managed to mimic the structure and function of the crocodile’s sensory organ to develop a highly stretchable pressure sensor. By inventing a hemispherical elastomeric polymer with delicate folds containing either long or short nanowires, they have created a device that outperforms currently available pressure sensors. While other sensors lose sensitivity when mechanically deformed, this new sensor maintains its sensitivity when stretched in one or two different directions.

Thanks to the fine fold structure on its surface, the sensor retains a high level of pressure sensitivity, even when severely deformed. When an external mechanical force is applied, the wrinkled structure unfolds, reducing the stress on the hemispherical sensing area responsible for detecting the applied pressure. As a result of this stress reduction, the sensor retains its pressure sensitivity even in the event of deformation. As a result, the new sensor has excellent pressure sensitivity, even when stretched up to 100% in one direction and 50% in two different directions.

The research team has developed a stretchable pressure sensor suitable for a variety of wearable devices with different applications. To evaluate its performance, the researchers mounted the sensor on a plastic crocodile and submerged it in water. Interestingly, the mounted sensor was able to detect small water waves, successfully emulating the perceptive abilities of a crocodile’s sensory organ.

‘This is a wearable pressure sensor that effectively detects pressure even under tension,’ explained Professor Cho, who led the team. He added: “It could be used for various applications such as pressure sensors in prosthetics, electronic skin of soft robotics, VR, AR and human-machine interfaces.”

The study was conducted with the support of the National Research Foundation of Korea of ​​the Ministry of Science and ICT and the Key Research Institutes in Universities program of the Ministry of Education. The research paper appeared on the cover of Small.