green-microchip
Technology Planning and Analysis

The wooden microchips and screens of the future

There are literally billions of mobile phones, computers, tablets and other bits of technology out there. And with the arrival of the Internet of Things, analysts predict dozens of billions more being created every year. With eWaste already a 50 billion ton large (and growing) problem that causes plenty of harm to both people and planet, isn’t it time we did something?

Why we need wooden microchips

“Eventually we are going to have more and more gadgets, gadgets that for the most part have not been imagined by us,” says Professor Zhenqiang "Jack" Ma, an electrical and computer engineering professor at the University of Wisconsin-Madison. “All these devices will be dumped as time goes by, so that’s why what I’m thinking about is that how we provide an alternative with wood, otherwise the materials will quickly be used up.”

The alternative he’s talking about is a new type of microchip he and his team of PhD students have developed. Instead of the usual materials such as gallium arsenide (GaAs) – a rare and toxic substance used for its semi-conductive properties – the semi-conductor’s support layers (also known as the substrate) are replaced with Cellulose Nanofibril (CNF) subtrate, a flexible, transparent, biodegradable material made from natural wood crystals. Much in the same way graphene is ultra-thin layers of carbon, CNF is just paper, a few nanometers thick. These nanoscale crystals were made into sheets of paper, then coated in a thin layer of epoxy resin to protect it.

According to the team’s snappily-named research paper, High-performance green flexible electronics based on biodegradable cellulose nanofibril paper, the chip performs on par with the kinds of chips you’ll find in your own smartphone, yet can be left in the forest to decompose and are “as safe as fertilizer”. The CNF chips still use a thin layer of gallium arsenide, but an amount that is around 3,000 to 5,000 times less than a normal chip would require.

The road to drinkable paper

Professor Ma has long been concerned with the issue of eWaste. “In 2007, I read a magazine that reported that in US, per day, people were discarding 426,000 mobile phones that are still working. Those numbers shocked me.” He recalls that most summers his university’s hallways are full of dumped computers due to be replaced.

This meant he was happy to help when Professor Shaoqin “Sarah” Gong, a biomedical engineer who was working with the Madison-based US Department of Agriculture Forest Products Laboratory (FPL), came to see if there was a way to combine the flexible nanomembrane technology Ma and his team had been working on with wood-based biomaterial for new applications.

“I say ‘let's talk’. I have no idea whether it’s going to work or not. So then we sit together,” he explains, “and I tell them, I feel like there’s opportunity there."”

Those initial meetings led to two and a half years of development to make sure that these new chips were as good as the toxic incumbents. The first test was ensuring that it possesses the correct thermal qualities and wouldn’t expand or melt at too low a temperature; the second was to ensure that it had a low level of radio frequency energy loss (an important factor in wireless communications). Early tests proved fruitful.

“We thought after testing, ‘oh my god, this is great material’,” says Ma. “It's very, very flexible, thermal expansion co-efficient is smaller than plastic we had been using.”

cellulose-nanofibril-wood-microchip-1

The last issue to solve was ensuring the chip was biodegrable yet wouldn’t turn to mulch is accidently exposed to moisture. “It’s a wood-based material. Once you put it in water, get moisture, it’s going to expand and then it’s going to decompose, and we don’t want that to happen.”

The answer? A thin layer of epoxy to act a barrier, problem solved. While there was worry that this epoxy may impact how the chips decompose, the team found certain fungi had no problem with the extra layer. “After we’ve finished all transistors, circuitry etc. - the performance is as good as the one that other people are doing on the regular way. So that was really surprising.”

Just to prove a point about how environmentally friendly these chips are, you could basically blend them into your smoothie. “Because we use so little [toxic material], we found if we throw these chips in the drinking water, it's still safe!” explains Ma – referring to the fact the chips use so little Gallium Arsenide, it passes Environmental Protection Agency standards for safe drinking water.

The potential for wooden screens and beyond

The paper industry is hundreds of years old, and so the processes are obviously about as mature and efficient as they’re going to get – which bodes well for this technology. “Paper is co cheap; imagine a sheet of A4 – on paper this size you can make almost millions of transistors.”

While the focus so far has been around consumer mobiles, it’s not only microchips Professor Ma thinks this technology could help. The transparency of the CNF paper is greater than glass, and so offers a potential alternative for the millions of screens in the world as well as an option for solar cells, while if made thicker there’s potential as a renewable phone casing. And that’s just for a start.

“Flexible electronics components will be produced a lot more than regular ones in the next 10 or 20 years,” says the professor, who thinks the thin and flexible nature of CNF could provide a low-cost alternative.

A patent for this technology was filed in May, and once that’s cleared, Ma and his team will start looking for investors and work towards commercialising the technology [other stories on the paper have reported that one unnamed firm is interested in the technology]. For now the major challenge is getting the time to work on it. “We have over 30 projects we're working on, some of the things we are trying to commercialise, this is just one of them.”

The future of microchips

Although there’s still more research to be done, the technology is basically ready. Professor Ma says that a whole phone made of biodegradable material could be a reality within the next decade. “I feel like, technology-wise, less than five years, for sure. I think maybe in two or three years if we had the resources. There’s no big technical barriers anymore.”

“But the major thing is whether really we can really bring [it] to market.” Because despite the potential of this technology, Ma doubts that we’ll we see chipmakers changing their habits and adopting the concept any time soon. “Their profits and margins are getting smaller and smaller because of competition, the main reason they can earn money is because they can produce a lot. So will they [chipmakers] change their whole processes? I really doubt it. They don’t care about the environment and nobody presses them to do it.”

Despite his pessimism, Professor Ma does have faith that the industry can eventually change. “The final product assembly companies - like Apple or Samsung - they buy chips from the chip makers and put them together,” he explains. “If their customers said, ‘ok we want our devices - the Galaxies, iPhones etc. - to become flexible or transparent’ they would think it's time to make a change. But that takes time.”

For now Ma thinks that it’s up to him and his team to create “something really fancy on the product side” to take to the likes of Samsung or Apple to show them that the technology really does work and is ready. “Technology-wise, I think it’s easy. But in terms of how to steer the market direction, that takes a lot of effort.”

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Dan Swinhoe

Dan is a journalist at CSO Online. Previously he was Senior Staff Writer at IDG Connect.

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