Electronic devices, such as cell phones, are a rapidly increasing source of waste. One solution could be to use components made from renewable resources that are easy to dispose of responsibly. Researchers have now created a prototype circuit board made of sheet paper with fully integrated electrical components that can be burned or left to degrade, as reported in ACS Applied Materials & Interfaces.
The majority of small electronic devices use circuit boards made of glass fibers, resins, and metal wiring. Because these boards are difficult to recycle and bulky, they are unsuitable for use in point-of-care medical devices, environmental monitors, or personal wearable devices. One alternative is to use paper-based circuit boards, which should be easier to dispose of, less expensive, and more flexible.
Tests confirmed that the resistor, capacitor, and transistor designs performed properly. The final circuit was very flexible and thin, just like paper, even after adding the components. To demonstrate the degradability of the circuit, the team showed that the entire unit quickly burned to ash after being lit on fire.
Current options, on the other hand, require specialized paper or simply have traditional metal circuitry components mounted onto a sheet of paper. Choi and colleagues instead wanted to create circuitry that was easy to manufacture and had all of the electronic components fully integrated into the sheet.
The team created a paper-based amplifier circuit with resistors, capacitors, and a transistor. They began by printing channels in a simple pattern onto a sheet of paper with wax. The team printed semi-conductive and conductive inks into the areas not blocked by wax after melting the wax and allowing it to soak into the paper. The researchers then screen-printed additional conductive metal components onto the sheet before casting a gel-based electrolyte on top.
Tests confirmed that the resistor, capacitor, and transistor designs performed properly. The final circuit was very flexible and thin, just like paper, even after adding the components. 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.
The results of the tests showed that the resistor, capacitor, and transistor designs worked properly. This low-cost but functional amplifier-type circuit board was as thin and flexible as paper. The primary goal of the research is to create a low-cost, environmentally friendly, all-paper device for single-use applications that can be easily and safely disposed of via incineration or biodegradation.
To demonstrate the circuit’s degradability, the team set fire to the entire unit, which quickly burned to ash. According to the researchers, this is a step toward producing completely disposable electronic devices.
The authors acknowledge funding from the National Science Foundation.
