Smart clothing can potentially track our heart rate, monitor our emotions or even pay for your morning coffee. Yet smart clothing is still to go mainstream. To help push the concept forwards, technologists working at the Massachusetts Institute of Technology have shown that it is possible to embed and connect high speed optoelectronic semiconductor devices inside fabrics. This innovation extends to light-emitting diodes.
As well as LEDs, the researchers also succeeded in fitting diode photodetectors impermeably within polymer fibers. A photodiode is a semiconductor device that converts light into an electrical current. The current is generated when photons are absorbed in the photodiode, and this type of technology is useful when developing wearable technology.
The new research began with a polymer fiber preform, where the bulk contained hundreds of micro-sized LEDs. These were situated alongside hollow channels. Through the channels, the researchers fed tungsten wires at the same time the preform was heated up.
This process of mechanical deformation, as EE News reports, allowed the conducting wires to make contact with the embedded devices. At the same time the electronics were safely encased within the fiber. The technology allowed the scientists to successfully connect hundreds of diodes in parallel inside a single fiber, with each device spaced just 20 centimeters apart.
The study to date used two forms of in-fiber devices. These were light-emitting and photodetecting p–i–n diodes. This enabled the researchers to establish a three-megahertz bi-directional optical communication link between two fabrics woven with receiver–emitter fibers.
The new fibers proved robust and were able to survive ten machine-wash cycles. This overcomes another weakness with wearable technology – after a while, it needs to be laundered.
Furthermore, the fibres can be woven into fabrics by conventional industrial manufacturing-scale looms. This means the approach could find commercial use within a very short time frame.
The research has been published in the science journal Nature. The research paper is called “Diode fibres for fabric-based optical communications”.
