Up to now, wearable sensors and other smart devices have relied on Bluetooth or Wi-Fi communications with the user’s smartphone to transmit and receive data. But as wearable devices increase in number and complexity, researchers are looking into other connection methods.
Researchers from the National University of Singapore (NUS) have invented a new way for wearable devices to interconnect. They incorporated conductive textiles into clothing to dynamically connect several wearable devices at once. This 'wireless body sensor network' allows devices to transmit data with 1,000 times stronger signals than conventional technologies, thus improving device battery life. Wireless networks of these wearable devices on a body have future applications in health monitoring, medical interventions and human-machine interfaces.
This technological breakthrough, was published in Nature Electronics on June 17.
National University of Singapore (NUS) researchers have incorporated conductive textiles into clothing to connect several wearable devices at once. The wireless body sensor network allows devices to transmit data with 1,000 times stronger signals than conventional technologies.
NUS Assistant Professor John Ho and his team from the Institute for Health Innovation & Technology (NUS iHealthtech) and the NUS Faculty of Engineering wanted to confine the signals between the sensors closer to the body to improve efficiency.
Their solution was to enhance regular clothing with conductive textiles known as metamaterials. Rather than sending waves into surrounding space, these metamaterials are able to create 'surface waves' which can glide wirelessly around the body on the clothes. This helps keep the energy of the signal between devices close to the body, rather than spread in all directions. Hence, the wearable electronics use much less power than normal, and the devices can 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 said in a statement. 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.
According to the researchers, one advantage of this method is that it does not require any changes to either the smartphone or the Bluetooth device, as the metamaterial works with any existing wireless device in the designed frequency band.
Security could be another benefit. Currently, radio waves transmit signals several meters outwards from the person wearing the device, making personal and sensitive information vulnerable to potential eavesdroppers. By confining the wireless communication signal to within 10 centimeters of the body, Ho and his team have created a network which is more secure.
The team has a first-year provisional patent on the metamaterial textile design, which comprises 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 costs just few dollars per meter, and can be bought readily in rolls.
"We started with a specific metamaterial that was both flat and could support surface waves. We had to redesign the structure so that it could work at the frequencies used for Bluetooth and Wi-Fi, perform well even when close to the human body, and could be mass produced by cutting sheets of conductive textile," Ho explained.
The smart textiles can be folded and bent with minimal signal strength loss, and 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.
The researchers are seeking potential partners to commercialize this technology. In the near future, Ho hopes to test the 'smart' textiles as specialized athletic clothing and for hospital patients to monitor performances and health.