Single-use paper circuit boards can burn to the ground when discarded.

Disposable electronic devices are a problem because the heavy metals and other toxic materials they contain are not allowed to enter the environment and are difficult to dispose of. Scientists have developed a solution in the form of a paper printed circuit board.

Led by Professor Seokeun Choi, the team at Binghamton University began printing a pattern of wax channels on a single sheet of filter paper. This paper was then baked in an oven, causing the wax to melt and soak into the underlying paper, but only in the areas where the wax had been applied.

The researchers then applied conductive and semiconductive inks to the paper. This ink is only absorbed in the parts of the paper that have not yet been soaked with wax, forming electrical circuits. These circuits were then screen printed with silver-based inks and other conductive metal components, after which a gel-based electrolyte was applied to the circuits.

The result is an inexpensive yet fully functional amplifier circuit board with resistors, capacitors and a transistor. It was thin and flexible, “just like paper”, and quickly and completely turned to ash when set on fire. The scientists argue that a paper circuit board can also be left to decompose after it is no longer needed, but what would happen to the metals in it in this scenario?

“While silver or other metals can be oxidized by microorganisms to biodegrade, it can take time and be harmful to the environment.”said Choi. “Clearly, all of our paper electronics will outperform traditional ready-to-use, non-biodegradable electronic components in terms of durability. […] My next task is to replace these non-biodegradable metals with biodegradable ones.”.

An article about the research was recently published published In the magazine ACS Applied Materials & Interfaces.

Source: American Chemical Society through EurekAlert