Printed electronics that decompose after use

Electronic waste is a huge global challenge and as manufacturing methods evolve to include printed electronics, the problem is not likely to disappear. Quite the opposite, printed electronics for one-time use in smart band-aids or on packaging could potentially aggravate the problem. Dr. Gerardo Hernandez-Sosa, a researcher at the Karlsruhe Institute for Technology (KIT) and leader of the Biolicht Young Investigator Group, decided to focus on finding a solution.

He and his group of young researchers at KIT developed a process to make printed electronics of compostable natural materials for industrial production. Today’s printed electronics don’t fit the bill: Even printed organic light emitting diodes (OLEDs) are not biodegradable. The adjective ‘organic’ in this context merely denotes the fact that these diodes are carbon based, but it doesn’t say anything about their impact on the environment.

After some experimentation, the KIT group honed in on some materials that are well suited as carriers and insulators: gelatin, starch, cellulose or chitin. The researchers are also working on developing biodegradable inks. The goal: After use, customers should be able to throw the electronic components in the compost bin where they should rot like an apple core or a banana peel.

To be useful in the real world, the researchers focus on two aspects: First, the printed electronics should perform as well as their conventional counterparts and be as durable and easy to use. Second, the material should be suited for printing with existing equipment. “Manufacturers of organic electronics can swap environmentally compatible materials without having to exchange their printer arsenal”, says Hernandez-Sosa. The German Federal Ministry of Education and Research funds the Young Investigator Group with a total of 1.7 million € over a period of four years.

Finding the right materials is not easy. Especially the ink that is used for printing circuits has to have different characteristics than conventional inks. It must not penetrate the carrier but should form a closed liquid film on the surface that doesn’t drip. If the ink is too thin, it will run off and if it is too thick, it will clog the pores of the printer. Finding the right carrier material also presents a challenge because it needs to be durable with a thickness of less than a thousandth of a millimeter and must not vary by more than 5 percent. Given the challenges that the materials and processes pose, the scientists have their work cut out for them. Still, they expect to have the first products ready for the market in about three years.