Single-use paper circuit board can be burnt to ash when discarded
Single-use electronic devices pose a challenge, as the heavy metals and other toxic materials in them shouldn't just be released into the environment, yet those substances are difficult to reclaim. Scientists have developed what could be a solution, in the form of a paper circuit board.
Led by Prof. Seokheun Choi, a team from the State University of New York at Binghamton started by printing a pattern of wax channels onto a single sheet of filter paper. That paper was then baked in an oven, causing the wax to melt and soak into the underlying paper – but only in the areas where that wax had been applied.
Next, the researchers applied conductive and semi-conductive inks to the paper. Those inks only soaked into the areas of the paper not already saturated with wax, forming circuits. A silver-based ink and other conductive metal components were then screen-printed onto those circuits, after which a gel-based electrolyte was applied over the circuitry.
What resulted was an inexpensive yet functional amplifier-type circuit board, complete with resistors, capacitors and a transistor. It was thin and flexible, "just like paper," plus it quickly and thoroughly burnt to ash when lit on fire. The scientists state that the paper circuit board could also be left to degrade once no longer needed – although what would happen to the metals in it, in that scenario?
"Although silver or other metals may be oxidized by microorganisms for biodegradation, it may take time and be harmful to the environment," Choi told us. "Obviously, our entire paper electronics will be much better than the conventional technique of using off-the-shelf non-biodegradable electronic components in terms of eco-friendliness [...] My next work is to replace those non-biodegradable metals with biodegradable ones."
A paper on the research was recently published in the journal ACS Applied Materials & Interfaces.