Disposable circuit board made from paper
Researchers have created a prototype circuit board that is made of a sheet of 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 fibres, resins and metal wiring. These boards are not easy to recycle and are relatively bulky, making them undesirable 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. However, current options require specialised paper, or they have traditional metal circuitry components mounted onto a sheet of paper. Instead, researchers are now striving to develop circuitry that would be simple to manufacture, with all the electronic components fully integrated into the sheet.
The research findings, reported in ACS Applied Materials & Interfaces, describe a paper-based, amplifier-type circuit designed by the researchers that incorporates resistors, capacitors and a transistor. The researchers first used wax to print channels onto a sheet of 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. Then, the researchers screen-printed additional conductive metal components and casted a gel-based electrolyte onto the sheet.
Tests confirmed that the resistor, capacitor and transistor designs performed properly. The final circuit was flexible and thin, just like paper, even after adding the components. To demonstrate the degradability of the circuit, the researchers showed that the entire unit quickly burned to ash after being lit on fire. The researchers said this represents a step towards producing completely disposable electronic devices.
To carry out their research, the authors received funding from the National Science Foundation.
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