“Help a shark!” Divers can gesture for help to the mainland with a new e-glove

The waterproof e-glove makes it easier for divers to communicate underwater. Not only with each other, but also with people on the mainland.

Communicating underwater is quite difficult for hearing people. There are tricks to get the other person’s attention by tapping the oxygen tank with a pebble or metal rod and there are even whiteboards that work underwater. But most underwater communication is done via hand gestures. Ideal for communicating over longer distances and without disturbing marine life. But if the view is blurred, or you want to communicate something to your ship, this method will fail.

To remedy that, Chinese researchers have developed a watch-tight e-glove that wirelessly transmits hand gestures to a computer that translates these messages. The new technology could help divers in the future to communicate better with each other and with people on the surface. The latter is particularly important when something goes wrong underwater. Getting caught in a strong current, for example, or when divers get lost in cave systems, something that can happen to even the most experienced cave divers.

What are you gesturing about underwater?
First of all, there are practical gestures, such as asking how much oxygen the other person has left, indicating that you are having difficulty clearing your ears or that you have to abort the dive. But there are also gestures to draw each other’s attention to underwater creatures. Do you see a shark? Then you place your hand on top of your head like a fin. Unless it’s a hammerhead shark, then place two fists on the sides of your head. With a Manta you flap both arms as if you were flying and with a jellyfish you move your hand while opening and closing your fingers like tentacles. For example, there is a real sign dictionary to communicate underwater.

Learn words
For their prototype, the researchers sewed ten waterproof sensors over the knuckles and index finger joints of the glove. These sensors, which are about the size of a USB-C port, detect and respond when bent. Then it was time to teach the glove some vocabulary. To do this, a participant made 16 hand gestures while wearing the gloves. The researchers then linked each gesture to the corresponding specific electronic signals. In this way, the computer program learned to translate sign language into words. The researchers tested this both above and under water. In both cases, the computer was able to provide a good translation in 99.8% of the cases.

Waterproofing
The e-glove uses the same principle as previous designs allowing the wearer to interact with virtual reality environments and allowing people recovering from stroke training to regain their fine motor skills (see box). To make this technology suitable for divers, this team specifically focused on making the electronic sensors waterproof. That turned out to be a tough task. The glove must be flexible and comfortable at the same time.

To achieve this, the researchers used waterproof sensors made up of flexible microscopic pillars, inspired by the tubular feet of a starfish. Using laser writing tools, they managed to place an array of these micropillars on a thin film of polydimethylsiloxane (PDMS), a waterproof plastic also commonly used in contact lenses. After covering this PDMS array with a conductive layer of silver, the researchers were able to place two of the films together with the pillars facing inward, creating a waterproof sensor. The researchers are satisfied with the end result. “The system has enormous potential for a wide range of applications in the field of underwater communications.”