Biodegradable displays

Biodegradable displays 1

Gold ink and gelatine are two substances used in innovative displays. Dr Gerardo Hernandez-Sosa and Manuel Pietsch from the Karlsruhe Institute of Technology are helping to create more eco-friendly electronics. Their flexible biodisplays are for example suitable for medical applications.

We are surrounded by computer displays in our daily lives. And that’s a problem, because the materials used in these devices are for the most part not biodegradable. In some cases they contain heavy metals. At the end of their useful lives, the screens are disposed of as electronic scrap. They cannot be recycled, or if they can this involves a very laborious and time-consuming process.

Dr Gerardo Hernandez-Sosa and Manuel Pietsch from the Karlsruhe Institute of Technology (KIT) want to improve the situation. Over the past seven years, they have developed small, flexible displays that compost down at the end of their service life. Their electrodes are made of gold, while the remaining components are made of organic compounds.

“They are so-called electrochromic displays”, explains Hernandez-Sosa, a physicist from Mexico. In such devices, the application of electric current causes a change in colour by changing the absorption of light. They consume very little energy. Though the technology of electrochromic displays has been around for 20 years, none of the devices has biodegradable components yet. 

Research collaboration between science and industry

Biodegradable displays 2

What is special about the production process is that the new displays can be created using an inkjet printer. “The printers we use function in the same way as standard office printers”, says Hernandez-Sosa. A kind of ink composed of gold particles is printed onto a cellulose diacetate base; an electrically conductive polymer is placed on top of it, and finally a gelatine gel. 

The two scientists have been conducting their experimental work at the InnovationLab in Heidelberg. The institution is based on a public-private partnership supported not only by the KIT, but also by the companies BASF, SAP and Heidelberger Druckmaschinen, as well as by Heidelberg University. “We have the printing machines we need at the InnovationLab”, explains Pietsch, a doctoral student in electrical engineering who was responsible for the experiments in the project. The InnovationLab was established by the ForumOrganicElectronics, a  cluster of excellence in the German government’s excellence initiative.

In 2014, Hernandez-Sosa became the head of a newly founded young research group that had received funding on the basis of the “NanoMatFutur” competition run by the Federal Ministry of Education and Research (BMBF). Later, Pietsch was given a position that allowed him to write his doctoral thesis at the same time. The successful project will be coming to an end in April 2021. The two scientists have already developed a prototype for a possible application: a mini display that can be applied directly to the skin for medical use, for instance. Coupled with a sensor, diabetes patients could use it to monitor their blood sugar levels.