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RESEARCHERS at the University of Wisconsin-Madison have developed a semiconductor chip made almost entirely of wood.
In a paper titled “High-performance green flexible electronics based on biodegradable cellulose nanofibril paper”, published in Nature Communications, the electrical and computer engineering researchers worked with the U.S. Department of Agriculture Forest Products Laboratory (FPL) to replace the substrate of a computer chip with cellulose nanofibril (CNF), which is a flexible, biodegradable material derived from wood.
According to the researchers, the majority of a semiconductor chip is supporting substrate, while less than a couple of micrometers provides the functionality on a chip.
By replacing the substrate with CNF, the chips become biodegradable and thus recyclable as compost.
CNF itself is made of wood fibres which have been broken down to the nano scale, which creates a very strong and transparent material.
But because wood is naturally hydroscopic, CNF will attract moisture from the air and expand. Electronics, on the other hand, need smooth surfaces and stability.
The researchers coated the CNF with an epoxy, solving both problems.
According to the researchers, while their process is more environmentally friendly, performance was similar to existing chips.
In conventional commercial gallium arsenide processes, a 5 by 6mm chip contains only 8 to 40 transistors. Using a deterministic assembly technique, it is possible to make 500 transistors on the same chip.
Using this same technique on CNF, it is possible to make a completely functional circuit with performance comparable to existing chips.