Discarded electronic devices are the world’s fastest-growing category of domestic waste, and most devices aren’t easy to recycle. The heavy metals and other toxic materials they contain should not just be released into the environment, yet those substances are difficult to reclaim.
Now, a team of researchers at the State University of New York at Binghamton has created a prototype circuit board that is made of sheet paper with fully integrated electrical components, and that can be burned or left to degrade.
Most small electronic devices contain circuit boards that are made from glass fibers, resins, and metal wiring. These boards are not easy to recycle and are relatively bulky. This makes them undesirable for use in point-of-care medical devices, environmental monitors, or personal wearable devices. The use paper-based circuit boards could be one of the alternatives, which should be easier to dispose of, less expensive, and more flexible.
Led by Prof. Seokheun Choi, a team designed a paper-based amplifier-type circuit that incorporated resistors, capacitors, and a transistor. They first used wax to print channels onto a single sheet of filter paper in a simple pattern.
After melting the wax so that it soaked into the paper, the team printed semi-conductive and conductive inks, which soaked into the areas not blocked by wax. Next, the researchers screen-printed additional conductive metal components and cast a gel-based electrolyte onto the sheet.
The tests confirmed that the resistor, capacitor, and transistor designs performed properly. This inexpensive yet functional amplifier-type circuit board was thin and flexible, just like paper.
The primary objective of the work is to develop a cost-effective, eco-friendly, all-paper device for single-use applications that can be easily and safely disposed of through incineration or biodegradation.
To demonstrate the degradability of the circuit, the team showed that the entire unit quickly burned to ash after being lit on fire. The researchers say this represents a step toward producing completely disposable electronic devices.
- Mya Landers, Anwar Elhadad, Maryam Rezaie, and Seokheun Choi. Integrated papertronic techniques: Highly customizable resistor, supercapacitor, and transistor circuitry on a single sheet of paper. ACS Applied Materials & Interfaces 2022, DOI: 10.1021/acsami.2c13503