Underwater movement sensors could have many applications, such as monitoring heart rate and tracking swimmers’ activity and safety. However, current methods to protect these electronics make the devices thick and impermeable to air. Also, the coatings required to completely seal these devices would make them uncomfortable to wear.
Now, a team of researchers from China and South Korea has applied a thin, slippery coating to conductive fabric, creating a breathable underwater movement sensor. They integrated the waterproof fabric-based underwater movement sensor into a smart device that wirelessly alerts a smartphone app when a swimmer stops moving, an indication that they could be drowning.
For this, the researchers dipped a piece of polyester knit fabric into a graphene oxide solution and then into hydroiodic acid. Then they immersed the fabric into a solution containing PDMS microparticles and nanoparticles.
Initial tests showed that the coated fabric was conductive and water-repellent yet still permeable to air, suggesting that the material would be comfortable to wear. It produced a measurable electrical response when a sample of the coated fabric was attached to a person’s finger that was then bent while underwater.
Researchers combined the fabric-based sensor with a power supply and a data collector to create a smart underwater movement system that could wirelessly transmit the electrical response to a smartphone app. To test the fabric-based sensor, the team attached it to a motorized swimming doll. As the doll moved its kicking legs, the sensor was able to track the movements. And when the doll stopped moving, the app received a red warning message.
The researchers say that because the smart underwater movement sensor repels water, it could help monitor swimmers’ safety and be used in other types of underwater sensors.
- Tianxue Zhu, Yimeng Ni, Kaiying Zhao, Jianying Huang, Yan Cheng, Mingzheng Ge, Cheolmin Park, and Yuekun Lai. A breathable knitted fabric-based smart system with enhanced superhydrophobicity for drowning alarming. ACS Nano 2022, DOI: 10.1021/acsnano.2c08325