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Stanford team makes e-waste disappear


Researchers at Stanford University have pioneered electronic components that are biodegradable.

This is a major step in the fight against the growing problem of e-waste. In 2017, some 50 million tons of electronic waste was thrown away, up 20% on 2015.

Motivated by the need to counter this, Stanford engineer Zhenan Bao said she and her team “have been trying to mimic the function of human skin to think about how to develop future electronic devices.” The aim was to replicate three desirable qualities found in human skin – ‘stretchable, self-healable and also biodegradable’.

“We have achieved the first two, so the biodegradability was something we wanted to tackle,” she said.

The team then made a device that could be degraded with a ‘weak acid like vinegar’. “This is the first example of a semiconductive polymer that can decompose,” said lead author Ting Lei, a postdoctoral fellow working with Bao.

As well as the polymer, Bao and her team developed ‘a degradable electronic circuit and a new biodegradable substrate material for mounting the electrical components’.

“We have been trying to think how we can achieve both great electronic property but also have the biodegradability,” Bao said.

She continued: “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. But also this chemical bond is sensitive to weak acid – even weaker than pure vinegar.”

There are a variety of potential application for biodegradable electronics. They could be ideal for wearables, implanted in the human body or used to conduct surveys in isolated areas. On the latter, Lei gives an example of dropping biodegradable electronics across a forrest to carry out a survey.

“It’s a very large area and very hard for people to spread the sensors,” he said. “Also, if you spread the sensors, it’s very hard to gather them back. You don’t want to contaminate the environment so we need something that can be decomposed.” The sensors would simply ‘biodegrade away’.

And he wants to develop more biodegradable products to tackle the issue of e-waste. “We currently have computers and cell phones and we generate millions and billions of cell phones, and it’s hard to decompose. We hope we can develop some materials that can be decomposed so there is less waste,” Lei added.

The research was published in the Proceedings of the National Academy of Sciences.

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