biodegradable electronic component on a human hair

[Image above] Biodegradable electronic polymer on a human hair. Credit: Ting Lei of Bao Group; Stanford University

We live in an age where most things can be recycled—paper, wood, glass, aluminum, plastic—you name it, and there will usually be somebody who wants to repurpose it. Which is a good thing for the planet.

But what about electronics?

Many consumers feel they need to buy the latest and greatest smartphone when a new model is introduced, without any thought or guilt as to where the old one will end up. When Congress required TV stations to broadcast exclusively in digital in 2009, many people probably discarded their analog TVs to purchase a new digital TV. What happens to all those electronics we don’t want anymore?

In 2013, U.S. consumers generated 3,140,000 tons of electronic waste, but only 40% of that was recycled—an increase from nearly 30% in 2012. Although recycling continues to slowly increase, the EPA says around 60% of discarded electronics ultimately end up in landfills.

As we replace our electronic devices more frequently, environmental costs will continue to rise.

Fortunately, scientists are concerned about this issue.

Stanford engineer and professor of chemical engineering and materials science engineering Zhenan Bao and her research group recently created a biodegradable electronic device that is characteristic of human skin—it’s flexible, self-healing, and can degrade simply by adding a weak acid such as vinegar.

“This is the first example of a semiconductive polymer that can decompose,” Ting Lei, a postdoc fellow and one of Bao’s researchers, says in a news release on the Stanford website.

The achievement follows the team’s previous research, in which the scientists created a flexible electrode from brittle plastic that was capable of interfacing with human skin. The one thing it couldn’t do was biodegrade—which was a challenge to Bao’s team.

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

stages of degradation in biodegradable electronic polymer

Stages of degradation over 30-day period. Credit: Ting Lei of Bao Group; Stanford University

The team also created an electronic circuit and a mounting surface, both of which are flexible and biodegradable. They made the electronic components out of iron, which is environmentally friendly and nontoxic—an important characteristic, as it allows the components to be inserted into the human body.

Bao’s research has important implications for the medical field. People can wear a device on the surface of their skin to measure blood pressure, glucose value, or sweat content for a period of time, then download the data, Bao says.

The researchers plan to further study the compatibility of inserting the polymer device into the human body, even though their research initially found it to be compatible.

Beyond medicine, Lei says biodegradable electronics could measure large areas of the world, such as forests, where they could be dropped from a plane to collect data for environmental researchers, and then eventually degrade into the earth.

As for our other electronic devices, including smartphones, perhaps one day we can toss them in the garbage after replacing them with the next model without the associated guilt trip.

The paper, published in Proceedings of the National Academy of Sciences of the United States of America is “Biocompatible and totally disintegrable semiconducting polymer for ultrathin and ultralightweight transient electronics” (DOI: 10.1073/pnas.1701478114).