These Zinc-Based Circuits Can Be Composted, Dissolved in Vinegar — Or Eaten
A new method for producing electronic circuits accepts almost anything as a substrate, from paper to chocolate.
Researchers from the University of Glasgow have come up with a new approach to building electronic circuits, printing zinc-based traces onto environmentally-friendly materials like bioplastics and paper — creating electronic devices that can be composted straight into the soil once they've outlived their usefulness, or even printed to chocolate and eaten at their end of their life.
"One key aspect of our work is that almost any substrate material can be used, ranging from paper and bioplastics for more realistic applications to chocolate for tasty but probably not very practical demonstrations," says corresponding author Jeff Kettle, professor at the University of Glasgow's James Watt School of Engineering. "We are now exploring ways to adapt this technique to other fields such as moldable electronics or biosensing, which could also benefit from a cheap and versatile way to make high quality circuits with low environmental footprints."
The team's research focused on what they term "a growth and transfer additive manufacturing process," which creates zinc traces just five microns wide on a temporary carrier material then transfers them to the target substrate — which, as Kettle says, can be almost any material, including those that easily biodegrade.
"The work demonstrates a major step toward circular electronics, where devices are designed from the outset for reuse, recycling, or safe degradation," says first author Jonathon Harwell of the work. "Discarded devices already generate tens of millions of tonnes of waste annually, so our research could have far-reaching impacts for consumer electronics, internet-of-things devices and disposable sensors in the future."
Prototype circuits produced using the method, which included tactile sensors, LED counters, and temperature sensors, showed stable performance even a year after manufacturing — but offered the ability for 99% of their materials to be safely disposed of through ordinary soil composting, or by dissolving the substrate in vinegar. Or, in the case of chocolate as a substrate, eaten.
The team's work has been published in the journal Communications Materials under open-access terms.