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Biodegradable solution to electronic waste

Stanford university researchers have created a biodegradable semi-conductor that can degrade with the addition of weak acids such as vinegar

The biodegradable semiconductor on a human hair. Photo: Bao Lab
The biodegradable semiconductor on a human hair. Photo: Bao Lab

This week: University of Stanford

In three years’ time, India could be generating 5.2 million metric tonnes of electronic waste annually. This is according to a June 2016 study on electronic waste management conducted by The Associated Chambers of Commerce & Industry of India (Assocham) and sustainability insights and capital advisory firm cKinetics.

Researchers at the University of Stanford in the US have now developed a biodegradable, flexible electronic device that could help reduce the amount of e-waste generated globally.

The team, led by Stanford engineer Zhenan Bao, has created a flexible semiconductor made from a biodegradable polymer that can easily do the job with the help of a weak acid like vinegar, which is commonly available. The results of the research were published in the Proceedings Of The National Academy Of Sciences journal on 1 May.

Essentially, the idea is to use the material in the manufacture of smartphones and other electronic items so that these can be disposed of with minimal effort once they are no longer in use.

“It is estimated that globally less than one-sixth of the e-waste generated is properly recycled or made available for reuse. Such an initiative will only help reduce the burden on formal recyclers to take care of the growing e-waste," says Hemal Damani, director, EcoCentric Management Pvt. Ltd, a Mumbai-based e-waste management company.

Damani says India is the fifth largest producer of e-waste, generating 2 million tonnes annually—less than 5% of this is formally recycled. The rest goes to the informal sector, which lacks the technical know-how for recycling and resource-recovery.

The device being developed at Stanford is still in the early stages of development, but it could be particularly useful for India in reducing not only the quantity of e-waste but in checking the need for manual recycling—the latter, says Damani, poses dangers both to the environment and the people involved in the trade.

According to a University of Stanford press release, Bao had previously created a stretchable electrode based on the functions and characteristics of the human skin. That material could bend and twist, but it wasn’t biodegradable.

Her team has now found a way of modifying the chemical structure of this flexible (polymer) material so that it breaks down easily. “We came up with an idea of making these molecules using a special type of chemical linkage that can retain the ability for the electron to smoothly transport along the molecule," Bao says in the press release. “But also this chemical bond is sensitive to weak acid—even weaker than pure vinegar."

The team has also developed a degradable electronic circuit and a biodegradable substrate material for carrying the semiconductor. This substrate material (made of cellulose) is also flexible and can mould to rough and smooth surfaces.

If electronic items are made with this biodegradable component in the future , then they could be disposed of easily. And while most components of electronic items are made of gold, the components of this device are made from iron, which is environment-friendly and non-toxic to humans.

The fact that the device can be worn on the skin or used as an implant could also make it useful for a variety of applications. “We envision these soft patches that are very thin and conformable to the skin that can measure blood pressure, glucose value, sweat content," adds Bao.

But the most exciting use so far seems to be in the role it could play in minimizing e-waste.

Lab Watch is the Lounge guide to emerging tech from around the world .

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