Underwater robotics and diving technology have just gotten a whole lot more resilient and intelligent thanks to a groundbreaking innovation in self-healing electronic skin. The research, led by Assistant Professor Tan Yu Jun from the National University of Singapore's College of Design and Engineering, introduces a self-healing magnetoelectric sensory system (SMES) that can sense damage and repair itself without external power. This technology has the potential to revolutionize underwater human-machine interfaces, from diving gloves to robotic hands, by providing durability and self-sufficiency in harsh environments.
A Living Skin for Electronics
The SMES draws inspiration from the remarkable capabilities of biological skin. Just like our skin can detect touch and pain, and heal itself after injury, the SMES can sense damage and initiate self-repair. The device consists of multiple layers, including a top damage-sensing layer and an electromagnetic sensing layer, both built on a stretchable, self-healing elastomer. This elastomer, laced with liquid-metal conductors, enables the sensor to mimic the pain response in living tissue when damaged.
When the top layer is pricked, punctured, or cut, its electrical resistance spikes, indicating damage. The self-healing property of the elastomer allows the material to bind back together or 'heal' when two damaged surfaces come into contact. For instance, after needle pricks, the sensor recovers its original electrical performance within seconds, and for more severe damage like cuts, it regains full functionality after a longer healing period.
The self-healing elastomer achieves impressive elastic recovery, reaching up to 92% and nearly 100% healing efficiency in air and water, respectively, after a specified period. This capability is particularly remarkable in underwater environments, where many materials struggle to bond back together.
Self-Powered and Built to Last
The SMES generates its own electrical signals through electromagnetic induction, eliminating the need for an external power source. A small magnet and a coil of liquid-metal wire are strategically placed in adjacent layers. When an object presses on the sensor or moves close to it, the magnet's relative position to the coil changes, inducing a voltage. This enables both proximity sensing and tactile sensing, making the device self-powered and suitable for underwater applications.
The sensor demonstrated exceptional response time, approximately 41 milliseconds, and maintained stable output after 10,000 cycles of usage, surpassing the benchmark for electronic skins. Its proximity-sensing performance remained consistent after 10 days of underwater immersion, including in simulated seawater.
From Diving Gloves to Robotic Hands
To showcase the real-world applications of the SMES, the research team developed two prototypes. The first is a smart diving glove that enables wireless underwater communication through hand gestures. Sensors on each fingertip generate distinct voltage patterns for different gestures, which are transmitted via Bluetooth to a smartphone. This allows divers to relay status updates without speaking, with five gestures mapping to commands like 'Normal', 'Going up', 'Going down', 'Holding', and 'Help'. Red LEDs on the glove light up when severe damage is detected, providing a real-time visual warning.
The second prototype is a robotic hand equipped with the SMES technology for underwater grasping and delivery tasks. Three LEDs indicate the sensor's damage status: green for normal operation, yellow for minor damage, and red for severe structural damage. During testing, the hand successfully grasped and transported objects underwater while detecting and recovering from puncture damage caused by sharp shells.
Looking Ahead
Assistant Professor Tan Yu Jun expressed his vision for the future integration of SMES with real robots, prosthetics, and wearable devices. The ultimate goal is to create soft machines that can sense their surroundings, recognize damage, and recover their function, much like living skin, even in unpredictable environments.
This innovation in self-healing electronic skin not only enhances the durability of underwater devices but also opens up new possibilities for human-machine interaction in challenging environments. As the technology continues to evolve, we can expect to see more sophisticated and self-sufficient underwater robots and diving equipment, contributing to safer and more efficient operations in the deep.
