MIT researchers have developed an autonomous programmable computer in the form of an elastic fibre, which could monitor health conditions and physical activity, alerting the wearer to potential health risks in real time.
Clothing containing the fibre computer was comfortable and machine washable, and the fibres were nearly imperceptible to the wearer, the researchers report.
Unlike on-body monitoring systems known as “wearables”, which are located at a single point like the chest, wrist, or finger, fabrics and apparel have the advantage of being in contact with large areas of the body close to vital organs. As such, they present a unique opportunity to measure and understand human physiology and health.
The fibre computer contains a series of microdevices, including sensors, a microcontroller, digital memory, Bluetooth modules, optical communications, and a battery, making up all the necessary components of a computer in a single elastic fibre.
The researchers added four fibre computers to a top and a pair of leggings, with the fibres running along each limb.
In their experiments, each independently programmable fibre computer operated a machine learning model that was trained autonomously to recognise exercises performed by the wearer, resulting in an average accuracy of about 70 percent.
Surprisingly, once the researchers allowed the individual fibre computers to communicate among themselves, their collective accuracy increased to nearly 95 percent.
“Our bodies broadcast gigabytes of data through the skin every second in the form of heat, sound, biochemicals, electrical potentials, and light, all of which carry information about our activities, emotions, and health,” says Yoel Fink, a Professor of materials science
and engineering at MIT.
“Unfortunately, most – if not all – of it gets absorbed and then lost in the clothes we wear. Wouldn’t it be great if we could teach clothes to capture, analyse, store, and communicate this important information in the form of valuable health and activity insights?”
The use of the fibre computer to understand health conditions and help prevent injury will soon undergo a significant real-world test as well.
US Army and Navy service members will be conducting a monthlong winter research mission to the Arctic, covering 1,000km in average temperatures of -40°F.
Dozens of base layer merino mesh shirts with fibre computers will be providing real-time information on the health and activity of the individuals participating in this mission, called Musk Ox II.
“In the not-too-distant future, fibre computers will allow us to run apps and get valuable health care and safety services from simple everyday apparel,” Fink says.
“We are excited to see glimpses of this future in the upcoming Arctic mission through our partners in the US Army, Navy, and DARPA. Helping to keep our service members safe in the harshest environments is an honour and privilege.”
Fibre focus
The fibre computer builds on more than a decade of work in the Fibers@MIT lab at the RLE and was supported primarily by ISN.
In previous papers, the researchers demonstrated methods for incorporating semiconductor devices, optical diodes, memory units, elastic electrical contacts, and sensors into fibres that could be formed into fabrics and garments.
“But we hit a wall in terms of the complexity of the
devices we could incorporate into the fibre because of how we were making it,” says Gupta.
“We had to rethink the whole process. At the same time, we wanted to make it elastic and flexible so it would match the properties of traditional fabrics.”
One of the challenges that researchers surmounted is the geometric mismatch between a cylindrical fibre and a planar chip.
“Connecting wires to small, conductive areas, known as pads, on the outside of each planar microdevice proved to be difficult and prone to failure because complex microdevices have many pads, making it increasingly difficult to find room to attach each wire reliably.
In this new design, the researchers map the 2D pad alignment of each microdevice to a 3D layout using a flexible circuit board called an interposer, which they wrapped into a cylinder.
They call this the “maki” design. Then, they attach four separate wires to the sides of the “maki” roll and connect all the components together.
“This advance was crucial for us in terms of being able to incorporate higher functionality computing elements, like the microcontroller and Bluetooth sensor, into the fibre,” says Gupta.
This versatile folding technique could be used with a variety of microelectronic devices, enabling them to incorporate additional functionality.
In addition, the researchers fabricated the new fibre computer using a type of thermoplastic elastomer that is several times more flexible than the thermoplastics they used previously.
This material enabled them to form a machine-washable, elastic fibre that can stretch more than 60 percent without failure.
They fabricate the fibre computer using a thermal
draw process that the Fibers@MIT group pioneered in the early 2000s.
The process involves creating a macroscopic version of the fibre computer, called a preform, that contains each connected microdevice.
This preform is hung in a furnace, melted, and pulled down to form a fibre, which also contains embedded lithium-ion batteries so it can power itself.
“A former group member, Juliette Marion, figured out how to create elastic conductors, so even when you stretch the fibre, the conductors don’t break,” Gupta says.
“We can maintain functionality while stretching it, which is crucial for processes like knitting, but also for clothes in general.”
Bring out the vote
Once the fibre computer is fabricated, the researchers use a braiding technique to cover the fibre with traditional yarns, such as polyester, merino wool, nylon, and even silk.
In addition to gathering data on the human body using sensors, each fibre computer incorporates LEDs and light sensors that enable multiple fibres in one garment to communicate, creating a textile network that can perform computation.
Each fibre computer also includes a Bluetooth communication system to send data wirelessly to a device like a smartphone, which can be read by a user.
The researchers leveraged these communication systems to create a textile network by sewing four fibre computers into a garment, one in each sleeve.
“Each fibre ran an independent neural network that was trained to identify exercises like squats, planks, arm circles, and lunges.
“What we found is that the ability of a fibre computer to identify human activity was only about 70 percent accurate when located
on a single limb, the arms or legs.
“However, when we allowed the fibres sitting on all four limbs to ‘vote,’ they collectively reached nearly 95 percent accuracy, demonstrating the importance of residing on multiple body areas and forming a network between autonomous fibre computers that does not need wires and interconnects,” Fink says.
Moving forward, the researchers want to use the interposer technique to incorporate additional microdevices.
Arctic insights
In February, a multinational team equipped with computing fabrics will travel for 30 days and 1,000km in the Arctic. The fabrics will help keep the team safe, and set the stage for future physiological “digital twinning” models.
“As a leader with more than a decade of Arctic operational experience, one of my main concerns is how to keep my team safe from debilitating cold weather injuries – a primary threat to operators in the extreme cold,” says US Army Major Mathew Hefner, the commander of Musk Ox II.
“Conventional systems just don’t provide me with a complete picture. We will be wearing the base layer computing fabrics on us 24/7 to help us better understand the body’s response to extreme cold and ultimately predict and prevent injury.”
Karl Friedl, US Army Research Institute of Environmental Medicine senior research scientist of performance physiology, noted that the MIT programmable computing fabric technology may become a “game changer for everyday lives.”
“Imagine near-term fibre computers in fabrics and apparel that sense and respond to the environment and to the physiological status of the individual, increasing comfort and performance, providing real-time health monitoring and providing protection against external threats.
“Soldiers will be the early adopters and beneficiaries of this new technology, integrated with AI systems using predictive physiological models and mission-relevant tools to enhance survivability in austere environments,” Friedl says.
“The convergence of classical fibres and fabrics with computation and machine learning has only begun.”