A recently developed underwater sensor offers new possibilities for tracking swimmers and divers, monitoring their movements to identify moments of distress and alert on-shore teams to potential drownings.

The design comes from a team at Fuzhou University in China and is one of the first times a device has been created that is waterproof, conductive, breathable and easy to wear. Existing designs rely on thick safety insulation that makes the wearables cumbersome and uncomfortable. 

To create the amphibious tracker, the team used a thin coating of a flexible, conductive fabric known as polydimethylsiloxane (PDMS) and tested its water-repelling efficacy when applied over a fabric sensor. 

Initial tests of the new design involved placing a sample of the fabric on a study participant’s finger before dipping it in water and having the participant move their finger. Results showed the coated fabric to be conductive and water-repellent, but still breathable and therefore, assumedly, comfortable.

In secondary tests the device was attached to a motorized doll programmed to kick or remain still, with the sensor’s response monitored. The sensor was integrated into a smartphone that sends alerts when a swimmer stops moving or shows erratic movement, with the device correctly identifying when the doll was still and when it was in motion, sending a red alert to the connected smartphone when no movement was detected.

The design could provide an easy-to-use safety wearable for divers embarking on security or maintenance missions, with consistent communication between these workers and the shore often challenging to maintain.