Green Circuit Boards That Biodegrade

With every new smartphone, tablet, or laptop consumers rush out to buy, there’s usually an older model that’s going to be thrown away. By some estimates as much as 25 million tons of electronic waste is produced globally each year. And roughly 82% of that waste winds up in landfills. Researchers led by John A. Rogers of the University of Illinois, Urbana-Champaign, report a way to make greener printed circuit boards—key components found in all but the simplest electronic devices—that could reduce e-waste. Printed circuit boards are usually made with metals such as gold, silver, palladium, tin, and copper configured with fiberglass or polyimide substrates. Rogers’s team has shown that these slow-to-degrade materials can be replaced by so-called transient metals such as magnesium, tungsten, and zinc formulated as micro- or nanoparticle paste and printed on biodegradable substrates such as sodium carboxymethylcellulose (Adv. Mater. 2014, DOI: 10.1002/adma.201403164). The researchers report that the biodegradable printed circuit boards disintegrate when immersed in water for about 10 minutes, leaving behind only the transient metals, which over the course of hours to days form soluble hydroxides.