3D-printed electronics can dissolve in water for quick recycling

Electronics such as Bluetooth speakers can be printed in 3D from a material that dissolves in the water in a few hours. This allows designers to quickly create prototypes, allows easier recycling of resulting electronic waste – and can even inspire more sustainable versions of mass electronics made in mass.

The researchers have demonstrated dissouvable technology in printed circuits, which contain the crucial components and the wiring of modern electronics. Hundreds of millions of printed circuits are manufactured each year for military fighter planes, cars, medical devices, smartphones and cheap toys. But the world only recycles only a fraction of these devices in a “very raw manner”, shouting them to extract reusable materials, explains HuaiHu Peng at the University of Maryland.

Peng and his colleagues have designed 3D printed circuits using polyvinyl alcohol, a polymer that can dissolve in water. To form the wiring, they injected a metal alloy of Gallium-Indium into the channels of the circuit card printed in liquid form. And they manually placed electronic components on the board. An additional polymer glue has been applied to seal the circuits before drying the device for an hour at 60 ° C.

Using these advice, the researchers assembled work versions of a Bluetooth speaker, a fidget toy and three fingers electronic pliers. A little water water will not instantly destroy such devices – but after 36 hours in water at room temperature at 22 ° C, the machines were dissolved.

Then the researchers easily chose the electronic components and most liquid metal, which were divided into small pearls. Once they evaporated the water, they were also able to recover 99% of dissolved polyvinyl alcohol.

Such printed circuit cards could be very useful when designers build quickly and test electronic prototypes, as it is generally difficult to recycle printed circuits, explains Jasmine Lu at the University of Chicago in Illinois, which has carried out related research on the reuse of circuit card materials. “If you are prototyping with electronics, printed circuits are a large source of electronic waste,” she says.

A 2022 United Nations report has shown that Asia has generated 600,000 tonnes of printed circuits used while recycling only 17% of this type of electronic waste. Europe and North America have generated 300,000 tonnes of circuits printed each, Europe managing to recycle 61% of this electronic waste and North America 44%.

The fact that anyone with a 3D printer can adopt this dissolved electronic approach makes it particularly unique compared to other sustainable electronics efforts, explains Lu. During use, suggests Peng, devices could be protected more with temporary waterproof cases.

But the limited sustainability of printed circuits currently makes electronics dissolved better suited to the rapid prototyping of conceptions, rather than the manufacture of mass of finished electronic products, explains LU.

Peng and his colleagues have not excluded mass manufacturing – they contact the producers of printed circuits to explore how it could work. But for the moment, Peng plans that its university students benefit from the technique for rapid prototyping and reuse.

“You usually have to outsource in factories to make the printed circuit, and this can take weeks to ship,” he said. “Here, you design something, print within 30 minutes, then you have a circuit – and if it doesn’t work, you dissolve it in the water for new things.”