Pohang: For a number of industries, including robotics, prosthetic limbs, health careand rehabilitation, electronic skin with many senses is crucial. Stretchable Pressure Sensorsthat can recognize different types of touch and pressure, are one of the main elements of this technology. ATTITUDE and the ulsan university in Korea recently collaborated to develop omnidirectional elastic pressure sensors that were inspired by crocodile skinwhich represents a significant advance.
The team behind the research was led by Professor Kilwon Cho, Dr. Giwon Lee and Dr. Jonghyun Son from POSTECH’s Department of Chemical Engineering, together with a team led by Professor Seung Goo Lee from Ulsan University’s Department of Chemistry. They were inspired by the unique sensory organ of crocodile skin and developed pressure sensors with microdomes and rough surfaces. The result was an omnidirectionally stretchable pressure sensor.
Formidable predators that spend most of their time submerged underwater, crocodiles possess a remarkable ability to sense small waves and detect the direction of their prey. This ability is made possible by an incredibly sophisticated and sensitive sensory organ located in his skin. The organ is composed of hemispherical sensory protuberances arranged in a repeating pattern with crinkled hinges between them. When the crocodile moves its body, the hinges deform while the sensory part is not affected by mechanical deformations, which allows the crocodile to maintain an exceptional level of sensitivity to external stimuli while swimming or hunting underwater.
The research team has successfully mimicked 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 wrinkles containing either long or short nanowires, they have created a device that outperforms currently available pressure sensors. While other sensors lose sensitivity when subjected to mechanical deformation, this new sensor maintains its sensitivity even when stretched in one or two different directions.
Thanks to the fine rough structure of its surface, the sensor can maintain high pressure sensitivity even when subjected to significant deformation. When an external mechanical force is applied, the wrinkled structure unfolds, reducing stress on the hemispherical sensing area that is responsible for sensing the applied pressure. This stress reduction allows the sensor to retain its pressure sensitivity even under deformation. As a result, the new sensor shows exceptional sensitivity to pressure, 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 wide range of wearable devices with various applications. To test 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 waves of water, successfully replicating the detection capabilities of a crocodile’s sensory organ.
“This is a wearable pressure sensor that effectively senses pressure even when under stress,” explained Professor Cho, who led the team. He added: “It could be used for various applications such as prosthetic pressure sensors, soft robotics electronic skin, VR, AR, and human-machine interfaces.”
