Low Energy, High Security Sensors You Can Wear

Researchers have used metamaterials to create smart textiles that can connect multiple wearable devices more securely.

AsianScientist (Aug. 13, 2019) – In an article published on the cover of Nature Electronics, researchers describe a smart textile that can transmit data 1,000 times more effectively than conventional methods.

Almost all existing body sensors connect to smartphones and other wearable electronics via radio-waves like Bluetooth and Wi-Fi. These waves radiate outwards in all directions, meaning that most of the energy is lost to the surrounding area. This method of connectivity drastically reduces the efficiency of the wearable technology as most of its battery life is consumed in attempting the connection.

To improve the efficiency of communication between wearable devices, a team of researchers led by Assistant Professor John Ho at the National University of Singapore sought to confine the communication signals closer to the body. To do so, they turned to metamaterials, which use ‘surface waves’ that can glide wirelessly around the body on the clothes. By confining the wireless communication signal to within 10 centimeters of the body, the team was able to reduce power consumption and detect much weaker signals.

“This innovation allows for the perfect transmission of data between devices at power levels that are 1,000 times reduced. Or, alternatively, these metamaterial textiles could boost the received signal by 1,000 times which could give you dramatically higher data rates for the same power,” Ho explained.

In fact, the signal between devices is so strong that it is possible to wirelessly transmit power from a smartphone to the device itself, opening the door for battery-free wearable devices. Crucially, this signal boost does not require any changes to either the smartphone or the Bluetooth device; the metamaterial works with any existing wireless device in the designed frequency band.

Furthermore, this metamaterial-based network also provides more privacy than conventional radio-wave transmission which sends signals several meters outwards from the person wearing the device.

The team has a first-year provisional patent on the metamaterial textile design, which consists of a comb-shaped strip of metamaterial on top of the clothing with an unpatterned conductor layer underneath. These strips can then be arranged on clothing in any pattern necessary to connect all areas of the body. The metamaterial itself is cost-effective, in the range of a few dollars per meter, and can be bought readily in rolls.

Once made, the ‘smart’ clothes are highly robust. They can be folded and bent with minimal loss to the signal strength. The conductive strips can even be cut or torn without inhibiting the wireless capabilities. The garments can also be washed, dried and ironed just like normal clothing.

Potential applications could range from measuring a patient’s vital signs without inhibiting their freedom of motion to adjusting the volume in an athlete’s wireless headphones with a single hand motion.

“We envision that endowing athletic wear, medical clothing and other apparel with such advanced electromagnetic capabilities can enhance our ability to perceive and interact with the world around us,” Ho said.

The article can be found at: Tian et al. (2019) Wireless Body Sensor Networks Based on Metamaterial Textiles.


Source: National University of Singapore.
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