Researchers Developing Printed Electronics Using Gravure Press for Creating RFID Tags

European researchers have taken a major step towards the goal of developing printable electronics that can be used for creating radio frequency identification tags and flexible watch displays.

Researchers have long dreamed of being able to print electronic components directly onto organic materials such as paper, fabrics, or plastic.

In addition to being able to fabricate large numbers of everyday devices such as watch displays and other applications cheaply, they envision novel applications including electronic paper, eyeglasses with embedded displays, or even smart clothing.

Researchers in the EU-funded CONTACT project have demonstrated that with suitable inks and printers, organic liquid crystal displays and other optical electronic devices can be printed out precisely.

The Technical University of Ilmenau, a CONTACT partner, has shown that within the printing process patterned glass plates can be used.

The project researchers hope to follow this proof-of-principle by developing a state-of-the-art gravure printing press, called Labratester 2. The press will be able to print hundreds of thousands of organic thin film transistor (TFT) arrays or other devices precisely and efficiently.

Labratester 2 is currently being finalized by Switzerland-based Schläefli Machines, another project partner. The company’s challenge is to perfect the extremely precise machinery needed to correctly align the layers of materials needed to form arrays of organic TFTs and other circuit elements.

Obstacles overcome Project coordinator Alan Mosley says that the most challenging problem the project team encountered was when they tried to lay down the first layer of a liquid crystal display over the TFT array they had already printed.

“What we found was that when we put down the first layer associated with the liquid crystal manufacture, it destroyed the TFT layer,” he says. “You have to use aggressive solvents, which attack organic materials.”

Project researchers at the Imperial College London eventually found ways to modify the inks and other materials making up the TFT layer so as to resist the solvents. The result is a process for printing a TFT layer that is compatible with a liquid crystal display.