KAIST lift-off TFT

The photo above shows a small patch of thin plastic on a subject’s skin. How thin is the plastic? 0.004 mm, or about 1/25 of the width of a human hair. That’s thin. It’s not remarkable that this flexible patch of plastic is so thin; what’s remarkable is that it has all the electronic features required to create a display.

We often mention here that in order for Health Tech wearable devices to succeed, they must “disappear” into our lives. Like a room thermostat, they should unobtrusively do their job without the need for intervention, and be ready to share information as needed. Thick, inflexible displays are a problem for the long-term adoption of wearable devices. Researchers at the Korea Advanced Institute of Science and Technology (KAIST) have demonstrated technology that may solve this problem.

Modern displays are made up of a matrix of pixels that can be turned on and off individually. This requires one or more transistors at every pixel’s location. These are typically fabricated using thin-film transistor (TFT) technology, and this matrix forms the backplane that controls the display. The problem is that it’s difficult to create a tiny TFT matrix on plastic film. The researchers at KAIST have developed a process that creates the TFT matrix on a rigid substrate coated with a layer that responds to laser light. They then use a laser to remove the substrate, leaving just the TFT matrix which then is transferred to the plastic. The result is 83% transparent and survives repeated bending, at a much lower cost than other methods.

This process could make it possible to incorporate displays and other complex electronics in patches that are worn directly on the skin or attached to garments. It could make smaller and more sophisticated wearable devices practical.