Additive Manufacturing Ink Enables Electrochemically Switchable Polymers

Related Vendors

Universität Heidelberg

Wuxi InfiMotion Technology Co., Ltd.

Researchers from the universities of Heidelberg and Stuttgart (Germany) have succeeded in making so-called redox polymers usable for additive manufacturing with digital light processing. This novel "ink" enables the three-dimensional printing of electrochemically switchable, conductive polymers using a light-based process.

Digital Light Processing (DLP) is a light-based 3D printing process in which a photosensitive "ink" is shaped layer by layer into a three-dimensional object through selective UV light exposure. Compared to other additive manufacturing methods, DLP enables the rapid production of complex structures. "While the technology is already successfully used in fields such as dentistry, it has so far been challenging to use it for conductive polymers with applications in optoelectronics and to print them directly," explains Prof. Dr. Eva Blasco. The scientist and her team at the Institute for Molecular Systems Engineering and Advanced Materials at Heidelberg University are researching novel functional materials for 3D printing. The project was conducted in close collaboration with Prof. Dr. Sabine Ludwigs and her group at the Institute for Polymer Chemistry at the University of Stuttgart, who are experts in conductive polymers and electrochemical switching. The research team has now succeeded in making so-called redox polymers suitable for additive manufacturing with Digital Light Processing. The resulting complex two- and three-dimensional structures can be electrochemically manipulated to change their color, opening up new perspectives for the production of 3D-printed optoelectronic devices. The research was carried out within the framework of the graduate program "Mixed Ion-Electron Transport: From Fundamentals to Applications," supported by both universities.

Ink Remains Electrochemically Manipulable Even After Printing

The research teams from Heidelberg and Stuttgart universities (Germany) developed the methacrylate-based "ink," which carries redox-active carbazole groups. These redox units enable such materials to accept or release electrons within their polymer chain. As a result, they become electrically conductive and can change color depending on their oxidation or reduction state. In their current work, the scientists succeeded in using this photoconductive ink formulation to create structures that remain electrochemically manipulable and thus adjustable in their properties even after printing. "This was made possible through close interdisciplinary collaboration in our laboratories in Heidelberg and Stuttgart," emphasize Christian Delavier and Svenja Bechtold, who are working on their dissertations as part of the graduate program.

This process is fully reversible and can be controlled pixel by pixel depending on the structure. Particularly exciting is the control in the third dimension, i.e., concerning the height of the architectures.

Sabine Ludwigs

Using this carbazole-based ink formulation, two-dimensional pixel arrays and checkerboard patterns, as well as a multi-layered three-dimensional pyramid, could be directly additively manufactured. Initially almost transparent, these complex structures turned light green, then dark green, and finally almost black through electrochemical stimulation. "This process is completely reversible and can be controlled pixel-precisely depending on the structure. Particularly exciting is the control in the third dimension, that is, with regard to the height of the architectures," emphasizes Sabine Ludwigs. According to Prof. Blasco and Prof. Ludwigs, the combination of high-resolution, light-based 3D printing with redox polymers opens up new possibilities for additive manufacturing of pixel displays or actuators for soft robotics applications, where volume can be electrochemically switched.

The graduate school "Mixed Ion-Electron Transport" (GRK 2948), based at the universities of Heidelberg and Stuttgart, is funded by the German Research Foundation. The results of the current research have been published in the journal "Advanced Functional Materials."

Future-Proof Authentication with Universal RFID Readers

Universal RFID Readers: One Solution for All Credentials