A team from the School of Electrical Engineering at KAIST (Korea Advanced Institute of Science and Technology) have developed a textile-based wearable display that's machine washable and powered by solar energy.
Clothes are usually formed with textiles and have to be both wearable and washable for daily use; however, smart clothing has had a problem with its power sources and moisture permeability, which causes the devices to malfunction. The team, Led by Prof Kyung Cheol Choi, created a textile-based wearable display module technology that does not require an external power source – they fabricated their wearable display modules on real textiles that integrated polymer solar cells (PSCs) with organic light emitting diodes (OLEDs).
According to KAIST, PSCs have been one of the most promising candidates for a next-generation power source, especially for wearable and optoelectronic applications because they can provide stable power without an external power source, while OLEDs can be driven with milliwatts.
However, the problem was that they are both very vulnerable to external moisture and oxygen. The encapsulation barrier is essential for their reliability. The conventional encapsulation barrier is sufficient for normal environments; however, it loses its characteristics in aqueous environments, such as water. It limits the commercialization of wearing displays that must operate even on rainy days or after washing.
To tackle this issue, the team employed a washable encapsulation barrier that can protect the device without losing its characteristics after washing through atomic layer deposition (ALD) and spin coating. With this encapsulation technology, the team confirmed that textile-based wearing display modules including PSCs, OLEDs, and the proposed encapsulation barrier exhibited little change in characteristics even after 20 washings with 10-minute cycles.
Finally, it exhibited no deterioration in properties over 30 days even after being subjected to both bending stress and washing. Since it uses a less stressful textile, compared to conventional wearable electronic devices that use traditional plastic substrates, this technology can accelerate the commercialization of wearing electronic devices. Importantly, this wearable electronic device in daily life can save energy through a self-powered system.
“I could say that this research realized a truly washable wearable electronic module in the sense that it uses daily wearable textiles instead of the plastic used in conventional wearable electronic devices," saidProfessor Choi said.
"Saving energy with PSCs, it can be self-powered, using nature-friendly solar energy, and washed. 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.”
This research, in collaboration with Prof Seok Ho Cho from Chonnam National University and led by Eun Gyo Jeong, was published in The Royal Society of Chemistry’s Energy and Environmental Science.