As electronic devices are becoming outdated at an increasingly fast pace, e-waste continues to be a huge problem. That's why scientists from the University of Wisconsin-Madison have started producing "wooden" semiconductor chips that could almost entirely biodegrade once left in a landfill. As an added bonus, the chips are also flexible, making them prime candidates for use in flexible electronics.
Although it would be neat to see a chip made from rich mahogany or knotty pine, the substrate of the UW-Madison chips is actually made of a translucent material known as Cellulose NanoFibrils (CNF) – it's also called nanofibrillated cellulose.
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As outlined in a previous Gizmag article on CNF, the material is typically made by adding water to cellulose-containing materials (usually wood waste, as would be found at paper or lumber mills) then using high-pressure homogenizers, grinders or microfluidizers to rip the wood fibers into much smaller cellulose nanofibers. This results in a gel which is subsequently freeze-dried to remove the water, leaving the long, interconnected nanofibers behind.
Working with the US Department of Agriculture's Forest Products Library, the researchers added an epoxy coating to the CNF. This made the substrate smooth enough for application of the non-CNF circuitry (which makes up only a small part of the total chip), plus it kept the material from expanding or contracting by taking on or releasing moisture.
Traditional chips use petroleum-based polymers for their substrates, which are non-biodegradable, require the use of non-renewable resources, contain toxic compounds, and aren't flexible.
The research was led by Prof. Zhenqiang "Jack" Ma, and was recently descried in a paper published in the journal Nature Communications.
Source: University of Wisconsin-Madison