Human hair used to make flexible displays for smart devices

  Last updated June 16, 2020 at 1:48 pm


When a researcher and a barbershop team up, the result could be flexible displays made out of human hair offcuts.

Why This Matters: The potential to use human hair could go beyond flexible screens.

There are some pretty weird ways you can use human hair, from clothing to cleaning up oil spills, and (one we didn’t expect) as an ingredient in soy sauce. Now, researchers from Queensland University of Technology are looking to use human hair to make our smart devices extra-flexible.

The team, led by professors Prashant Sonar and Ken Ostrikov have collaborated with researchers from Griffith University to create carbon nanodots from hair – tiny, uniform dots that are one-millionth of a millimetre.

These nanodots can then be used as a light-emitting layer on displays.

The research has been published in the journal Advanced Materials.

From nano-dots to flexi-screens

The carbon nanodots work in a similar way to the quantum dots that are already found on many LED TV’s. In those, the quantum dots form an active layer which converts blue LED light into relatively pure green or red colour. The conversion by the dots is very efficient and creates light with little crossover between colours, resulting in a picture that looks sharper and more vibrant.

The carbon nanodots can do the same but are more efficient, using only modest voltage to produce light. By using waste hair they’re also more eco-friendly, and have lower toxicity and higher stability than current quantum dots, say the researchers.

“Waste is a big problem,” says Sonar.

“The creation of valuable material from human hair waste that has potential uses in both display and sensing opens up an opportunity towards a circular economy and sustainable material technology.

According to the researchers, it’s the first time human hair waste has been turned into highly luminescent carbon nanomaterial from which flexible light-emitting devices are made.

Also: What is a ‘circular economy’ and why does Australia need one?

“We have proven it works for human hair. We’re now interested if we could get the same results from animal hair,” says Sonar.

“Perhaps we could produce flexible OLEDs using small strands of wool from sheep or leftover dog hair from pet grooming salons.”

Turning hair waste into ‘nano-islands’

First, the researchers needed a source of human hair, for which they turned to Brisbane barbershop Ben Scissorhands. Barber Benjamin Mir says he was happy to provide his offcuts to support the research project.

Barber Benjamin Mir with Associate Professor Prashant Sonar. Credit: QUT.

To create the carbon nanodots, the researchers then developed a two-step process that involved breaking down the hairs by burning them at 240 degrees Celsius.

Hair is a natural source of carbon and nitrogen, which are key elements to obtain light-emitting particles. Heating the hair strands breaks down the keratin, with the resulting material having both carbon and nitrogen embedded in its molecular structure, giving it favourable electrical properties.

The processed nanodots were uniformly dispersed in a polymer and then allowed to self-assemble to form “nano-islands”, or small groupings of the nanodots.

Also: Imagine touchscreens so thin you can roll and fold them

Carbon dots have a future as smart sensors

But the applications could go much further than just flexible screens. In fact, they found the dots probably aren’t bright enough for a TV screen, but could be used in a range of flexible screens from wearable devices to smart packaging.

“They could also be used where a small light source is required such as in signs or in smart bands and could be used in medical devices because of the non-toxicity of the material,” says Sonar.

One possibility is a smart milk bottle, with a sensor built inside to give a real-time update of the milk’s expiry. The information would then be displayed on a screen on the bottle itself.

The researchers are also interested in developing the nanodots into environmental sensors. In particular, work led by PhD student Amandeep Singh Pannu is developing ways to monitor chloroform levels in water treatment systems in real time.

Chloroform is one of the by-products when chlorine is used for water disinfection.  The World Health Organisation (WHO) has set a safe limit of chloroform of less than 300 parts per billion in drinking water.

So far the research has found the carbon dots made from human hair responded to the presence of chloroform with high sensitivity and selectivity.

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