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68: Biodegradable cell phone components

Problem:

Approximately 150 million mobile phones are discarded each year in the USA.

Solution:

Biodegradable cell phone components.


Although cell phones have the highest recycling market of any electronic material only 10 % of these are recycled while the rest may end up in a landfill, but more likely to end up in desk drawers or garages.

Jeremy Lang of Pela Case of Saskatoon, Saskatchewan Canada, using Flaxstic, a bioplastic made from flax straw has developed a cell phone case comprised of 35 – 45% biobased content (plant-based plastic and flax straw) and 55% non-renewable, biodegradable materials.

As a boy, Lang discovered that flax farmers were in the practice of burning their fields after a harvest, in order to prevent the strong flax straw from getting caught up in and ruining their farming equipment. He realized that if that flax straw was so strong, it could certainly be used for something.

Elsewhere Sprint and Samsung have each launched the Reclaim, a biodegradable handset that is 80% recyclable and comes with a 40% corn-based plastic cover. The Reclaim ditches a paper manual for a virtual one and comes with a charger that is more energy-efficient than standard chargers.

Sprint’s phone is nearly free of commonly used toxic materials such as polyvinyl chloride (PVC) and brominated flame retardant. And the company is donating US$2 from each sale to the Nature Conservancy’s Adopt an Acre Program.

Ideally the phone would be completely free of all toxic materials and have a solar charging option. But these are improvements that Sprint and Samsung will probably make in the future. Samsung has already developed a separate solar-powered phone.

Alongside the case, there is the screen. The Australian National University’s (ANU) Research School of Engineering created a semiconductor with both organic and inorganic materials that can convert electricity into light with a very high efficiency.

Engineers have developed an ultra-thin semiconductor featuring one-atom-thick organic material with two-atom-thick inorganic materials to make a new type of electronic screen.

The compound is incredibly thin and is just one atom thick. The carbon and hydrogen base makes up part of the semiconductor developed by the Australian team.

The inorganic compound is just two atoms. The super-thin biodegradable semiconductor would be ideal for screens and other displays on cell phones. The thin, flexible surface could also be used in an entirely new series of high-performance electronics. (eng.anu.edu.au)

But then there are the thousands of transistors inside a cell phone. The tiniest transistors are now less than 30 nanometers long. You could fit 16,000 of them, side-by-side, in the period at the end of this sentence.

For the internal components, Simon Vecchioni, who recently defended his Ph.D. in biomedical engineering at Columbia University, is using synthetic biology to produce DNA nanowires and networks as an alternative to silicon device technology.

Vecchioni ordered synthesized DNA from a company, used it to create his own custom BioBrick, a circular piece of DNA, and inserted it into the bacterium E.coli, which created copies of the DNA.

He then cut out a part of the DNA and inserted a silver ion into it, turning the DNA into a conductor of electricity. His next challenge is to turn the DNA nanowires into a network.

The DNA nanowires may one day replace wires made of valuable metals such as gold, silver (which Vecchioni only uses at the atomic scale), platinum and iridium, and their ability to “self-assemble” could eliminate the use of the toxic processing chemicals used to etch silicon.

As silicon transistors (the devices that carry the 1s and 0s of computers) start to bump up against the limits of physics in terms of size and density, the evidence so far points to carbon nanotubes being a faster and more energy efficient option.

Processors (lots of transistors packed together) made from carbon nanotubes could help computing take the next leap forward. This would be by far the most advanced chip made from any emerging nanotechnology that is promising for high-performance and energy-efficient computing.

After the first carbon nanotube (CNT) transistor was created in 1998, researchers made progress by building other circuit elements such as logic gates.

In 2010, Desirée L. Plata, a civil and environmental engineering professor at Duke University, designed a research experiment to determine how chemical bonds are built during nanotube synthesis, with the goal of improving the manufacturability of CNTs and minimizing the environmental impacts of this technology.

Her study was published in 2010 in the American Chemical Society’s online journal ACSNano. But a computer with an all-nanotube central processor remained elusive.

Researchers from Stanford University said that they had successfully built a carbon nanotube computer and their research paper published on September 25, 2013 in the journal Nature. They named their prototype Cedric.

Six years later at the Massachusetts Institute of Technology, computer scientist Max Shulaker and a team have built a 16-bit processor (the more bits, the more complexity), functional enough to run a basic program, producing the words “Hello, World! I am RV16XNano, made from CNTs”.

In this new study, researchers used rolled up sheets of carbon, each a single atom thick, to form 14,000 carbon nanotube field-effect transistors (CNFETs) – up from a previous attempt in 2013 that managed 178 transistors. The researchers reckon these chips could be viable within five years. (eecs.mit.ud)

Discover Solution 69: cell phone components made from wood

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