The next five years in flexible electronics can be the most exciting we have witnessed if we can seize a bounty of opportunities and overcome remaining challenges.
Flexible electronics are made by adding layers of suitable materials onto flexible substrates. In contrast to silicon chip processing, fewer steps are needed and the temperatures are much lower
The main promise is that flexible electronics will be many times cheaper than today’s electronics. Also, we’ll be able to integrate applications directly in any material and with any form factor.
If we succeed, we will herald a new revolution, one in which we can make every object smart. From what I see in the labs, things are evolving fast and in the right direction.
The main challenge I see is that we now have to look how to scale our infant technology, giving it more juice and making it more energy-efficient at the same time. We know that it can be done in principle, but it will require some patient searching and tuning.
This is what I and other researchers hope to accomplish:
Make transistors smaller and circuits denser. So far we’ve only demonstrated a few circuits containing a few thousand transistors maximum. We’re still at the beginning of Moore’s Law for flexible electronics, and we should be able to go to 10,000 or even 100,000 transistors per square centimeter at a cost of one U.S. cent. That is a density where things start to get interesting, where we could build powerful, innovative applications.
Get a better grip on power consumption. The best material we currently have is an n-type thin-film semiconductor, a material with access to electrons causing electrical currents to flow between source and drain. Unlike in silicon CMOS technology, we don’t yet have a comparable p-type material that can counterbalance and stop that flow in digital circuits.
In our flexible circuits, there are always currents flowing between supply and ground. In the near and mid-term, my research is focused on finding circuit solutions with only n-type transistors that nevertheless reduce parasitic leakage currents. For complex circuits, it should be possible to lower power consumption by a factor 10 to 100.
Develop new fabrication techniques and tools. Today, large-scale production of flexible electronics is the realm of display makers. Their equipment produces features in the micrometer range. If we want to make transistors smaller and circuits denser, we’ll need submicron features. So we’ll need to develop a new generation of tools and production lines. Tool makers and manufacturing will need to step up.
As for applications, here are three that I’d like to help develop:
High-density displays for use in bendable, roll-able surfaces, glasses, or--who knows--even in contact lenses. A high-quality AR/VRexperience requires small, closely-spaced pixels, an order of magnitude denser than we can produce today.
Wearables or patches attached to the skin, measuring body parameters. Such patches could continuously monitor a wound that’s healing without bothering the patient. Longer-term, these devices could even replace smart watches.
Tags with on-board storage, sensors and data processing. Imagine we could design tags to check food quality and place them on apples, cheese packaging, or milk boxes. You would need a multi-parameter sensor maybe with some chemical processing. And you’ll also need processor circuits and a battery to do data analysis when the tag is not within reach of an antenna. Such devices could be the start of an item-level Internet of Things.
All these capabilities are already possible with silicon chips.It may seem a distant dream to reach the same level of sophistication with flexible electronics. However, if we can boost the density to where I hope we will, and if we can start a Moore’s Law for flexible electronics, then the dream will definitely become a reality.
--Kris Myny is a principal member of technical staff at the Imec research institute in Leuven, Belgium. In 2016, he received a grant from the European Research Council to further his work in thin-film transistor circuits, and he was recently featured as one of Belgium’s 50 tech pioneers.