UCLA Bioengineers Develop Artificial Skin to Outfit Underwater Robots with a Sense of Touch

Autonomous robots have been used for underwater exploration, but they are limited by the lack of human dexterity. Without a sense of touch, it is difficult for these robots to accomplish a variety of tasks requiring fine motor skills.

Led by Jun Chen, an assistant professor of bioengineering at the UCLA Samueli School of Engineering, a research team has created a new waterproof, artificial skin capable of underwater haptic sensing that can allow the robots to feel and handle objects. 

Published in Science Advances, the UCLA study describes the development of the artificial skin utilizing a magnetoelastic sensing mechanism the team invented in 2021. The technique causes a magnetoelastic material’s magnetic properties to shift when it is deformed, while maintaining its sensing performance even when it is immersed in water. In designing the skin, the team took inspiration from the somatosensory system, the network of neural structures in the brain and body responsible for producing the perception and sense of touch. The tactile information is then decoded by the neural network, resulting in more than 95% accuracy.

“Marine resources are difficult to access because of hypoxia, corrosion and high-pressure nature of the ocean,” said Chen who leads the Wearable Bioelectronics Research Group at UCLA. “Our new haptic sensing system is a key step toward achieving the goal of safer and more sustainable marine-resource exploration.”

The team demonstrated the technology by equipping a commercial robotic arm with a clamp wearing the artificial skin. With remote access, the researchers were able to detect and sense the properties of various objects and organisms under water. Prior attempts at underwater haptic sensing required covering a robot in layers of materials to keep it dry, which affected the machine’s sensitivity and sometimes the approach failed to stop leakage. The UCLA team’s waterproof skin protects the robotic arm from getting wet and increases its sensitivity to garner more subtle information, such as the direction, amplitude shape and vibration of an object. 

The magnetoelastic artificial skin also consumes much less energy than the conventional haptic sensing devices because of its self-powering capability. Tactile stimuli on the magnetoelastic artificial skin are spontaneously converted into analyzable electrical signals by the population response of the sensory channels in the device. These signals mimic the collective behavior of the human tactile system and are generated by the magnetoelastic artificial skin itself. By contrast, conventional haptic sensing devices rely on external power supply to generate such signals. 

In addition to its use in underwater exploration, the breakthrough also shows potential for multiple applications, including marine litter recycling, deep-sea construction, biological sampling and wearable human-machine interfaces.     

Other authors of the paper are UCLA Samueli undergraduate student Justin Li and graduate students Xun Zhao, Jing Xu, Guorui Chen and Trinny Tat, as well as postdoctoral scholar Yihao Zhou — all members of Chen’s lab. 

The work was funded by the U.S. Office of Naval Research, American Heart Association, Brain & Behavior Research Foundation, National Institutes of Health’s National Center for Advancing Translational Science, UCLA Clinical and Translational Science Institute, Children’s Hospital Los Angeles and UCLA Samueli School of Engineering.

The team is currently working on commercializing the technology and testing its performance in the ocean.