Washable smart clothes a reality
Smart clothing has always faced issues with electronics’ age-old nemesis: moisture. A KAIST research team now reports it has developed a ‘washable’ wearable display that is self-powering.
When researchers from a KAIST research team developed wearable, woven screens made from OLED thread in 2018, the cynics among us questioned their viability as actual clothing due to the threat of water leading to the malfunctioning of the device, something the team now reports it has overcome.
The team claims it has developed a textile-based wearable display technology that can be washed and eliminates the need for an external power source.
To overcome the washing issue, Professor Jyung Cheol Choi from the School of Electrical Engineering and his team developed the wearable display module on textiles that integrated polymer solar cells (PSCs) with organic light emitting diodes (OLEDs).
Some experts have speculated that PSCs could be a candidate for future power sources in the realm of wearable and optoelectronic displays due to their ability to provide a consistent source of power without an external power source, with OLEDs able to driven with milliwatts.
In their current form, both PSCs and OLEDs are vulnerable to external moisture and oxygen; while a conventional encapsulation barrier is suitable for everyday environments, its characteristics are lost in water-rich environments which has led to a limit in market viability for wearable displays as they will not be able to operate on rainy days or will fail after washing.
The team used a washable encapsulation barrier to protect the device through atomic layer deposition (ALD), a vapour phase technique used to deposit thin films onto a layer of fabric.
A spin coating technique was also used, a procedure used to deposit uniform thin films to flat layers.
Using these techniques, the team confirmed that wearable displays including PSC, OLEDs and an encapsulation barrier showed little change in characteristics after 20 washings with 10 minute cycles.
The encapsulated device was reported to operate stably with a curvature radius of 3mm. In addition, no deterioration in properties were detected over a 30 day period after being subjected to bending stress and washing. This was achieved by using a textile which exhibited less stressful qualities, instead of the conventional plastic textiles which are typically used in wearable electronics.
The team have not confirmed whether a product based on the technology will soon be on the market, but Professor Choi believes that a landmark for durable wearable displays has been reached.
He said “I believe that it has paved the way for a ‘true-meaning wearable display’ that can be formed on textile, beyond the attachable form of wearable technology.”