Researchers at the National University of Singapore (NUS) have invented a completely 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 signal than conventional technologies, meaning the battery life of all devices is dramatically improved. Wireless networks of these wearable devices on a body have future applications in health monitoring, medical interventions, and human-machine interfaces.
This technological breakthrough, which took the 10-member team a year to achieve, was published in the journal Nature Electronics.
Better Data Transmission, Greater Privacy
Currently, almost all body sensors (e.g., smart watches) connect to smartphones and other wearable electronics via radio waves like Bluetooth and Wi-Fi. These waves radiate outward 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 because most of its battery life is consumed in attempting the connection.
As such, Assistant Professor John Ho and his team from the Institute for Health Innovation & Technology (NUS iHealthtech) and NUS 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” that can glide wirelessly around the body on the clothes. This means that the energy of the signal between devices is held 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.
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 designated frequency band. This inventive way of networking devices also provides more privacy than conventional methods. Currently, radio waves transmit signals several meters outward from the person wearing the device, meaning that personal and sensitive information could be vulnerable to potential eavesdroppers. By confining the wireless communication signal to within 10 cm of the body, the network is more secure.
Intelligent Design, Enhanced Capabilities
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.
“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, could perform well even when close to the human body, and could be mass produced by cutting sheets of conductive textile,” Ho explains.
The team’s design was created with the aid of a computer model to ensure successful communication in the radio-frequency range and to optimize overall efficacy. The smart clothing is then fabricated by laser cutting the conductive metamaterial and attaching the strips with fabric adhesive.
Once made, the smart clothes are highly robust. They can be folded and bent with minimal loss to the signal strength, 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 team is talking to potential partners to commercialize this technology, and in the near future, Ho is hoping to test the smart textiles as specialized athletic clothing and for hospital patients to monitor performance and health. Potential applications could include measuring a patient’s vital signs without inhibiting their freedom of motion.