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Printed Electronics World
Posted on August 24, 2016 by  & 

Do flexible electrodes make life easier?

A cell phone falls on the floor. It works, but the cracked screen resembles a spider's web. This and similar damage can be prevented by using flexible electrodes created by Grzegorz Wróblewski, PhD (Eng.) from the Faculty of Mechatronics at the Warsaw University of Technology.
To Print Electronics
However, the flexible electrode was not invented for use in phones, tablets, or computers. Wróblewski is a member of the research team of the Department of Microtechnology and Nanotechnology, Faculty of Mechatronics; its main area of expertise is printed electronics. "You can say that we print electronics like magazines", he explained. The team consists of 10-15 people. They are doctors and doctoral candidates working under the guidance of Professor Małgorzata Jakubowska.
Nowadays, printed electronics are mostly used to manufacture anti-theft devices for clothes (printed electronic labels), as well as membrane keyboards. However, the industry has a much larger potential. Printed electronics can represent an alternative to silicon technologies. Nevertheless, Wróblewski emphasises that they are not competing with them. "Let's leave theoretical considerations", he says. "We can't print a processor with the same parameters as silicon processors. Printed electronics can be used in sensor surfaces, antennas, conductive circuits, resistors or capacitors. We can mass produce cheap and biodegradable structures. We don't use cleanrooms or high temperatures, we don't have sophisticated technological processes; we only focus on simple and efficient techniques".
It's All About the Ink
The flexible electrode, Wróblewski's brainchild, is necessary to develop the printed electronics team's projects. Thanks to the technique of spray coating, layers he obtained using it were over 10, or even 100 times thinner than when using screen printing.
Wróblewski mainly uses carbon nanotubes to manufacture the electrodes, as they are quite cheap today. "The method itself is not complicated, but there are a couple of details you need to feel", he says. "It's all about good ink. I worked on it for 3 years".
Wróblewski explains that his work resembles painting a car. He calls the suspensions he uses inks. "They contain carbon nanotubes, graphene flakes, graphite nano fibres", he tells us. "In a container, the ink is black, but, after spraying it, a translucent conductive layer appears".
Dr Wróblewski's flexible electrode was recognized by the jury of the Innovators Under 35 competition, organized by "MIT Technology Review", a magazine of the Massachusetts Institute of Technology. At the competition's gala, the scientist from the WUT presented his idea by describing a cracked phone screen. "I selected this topic because it's the easiest way to imagine the use of flexible electronics", he explained.
Can we expect it to be used in screen manufacturing soon? "Let's not focus on that", says Wróblewski. "Current screens are made using ITO - indium tin oxide. Such layers are more transparent than ours, but also more fragile. Our layers, based on various carbon structures, can be folded 150 thousand times, and it won't negatively affect their parameters. ITO is considerably damaged after only 10 fold cycles".
All carbon electrodes are great in devices that have to be very flexible, and in large structures with complex shapes. It is also a great substrate with a richly developed surface, which can constitute a base for enzymes.
Source and top image: Warsaw University of Technology
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