Biodegradable Electronics Could End Toxic Trash

A future in which a discarded cell phone dissolves into a landfill, rather than living on for thousands of years as garbage, may not be that far off. Melissa Block talks with John A. Rogers, a 2009 MacArthur Fellow and professor of engineering at University of Illinois, about his research into "transient electronics."

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ROBERT SIEGEL, HOST:

New electronics have a way of getting smaller and smaller. And now, scientists may have found a way to make them disappear by making them bio-degradable. They envision at least three potential applications.

MELISSA BLOCK, HOST:

First, environmental. Imagine an oil spill. Scientists could drop thousands of tiny monitors into the water that would report where and how quickly the oil is dispersing. The monitors could then be programmed to dissolve with no adverse effects on the environment.

SIEGEL: Researchers also imagine biodegradable consumer electronics. Many people hold onto their smartphones for just two to three years before replacing them. Well, instead of the old phone winding up in a landfill, leaching toxins, imagine a phone that could breakdown when we're done with it.

BLOCK: John Rogers is leading the team behind all this. He's a professor of engineering at the University of Illinois, and I asked him to explain a third application for his biodegradable electronics. Imagine putting them into your body.

PROFESSOR JOHN ROGERS: Yeah, so if you think about clinical healthcare, there are many instances where you might want to insert into the body a piece of electronics that provides a diagnostic or sensing function or ability to interact with the tissue in a beneficial way, to, for example, accelerate a healing process or to prevent infections at a surgical site. And in those modes of use, the device function has a finite timeframe really set by the healing process itself. But once the individual is healed and on a path to recovery, the ideal situation is for the electronic device and the actuators and sensors to simply disappear.

BLOCK: So it's something that would be implanted. Can you describe what it looks like, how big it is, what it's made of?

ROGERS: So we use thin films of silk as a substrate, basically has the appearance of a thin sheet of plastic, which we then go in and build on top of that a silk platform. So we have materials from conductors, dialectrics, semiconductors, we can configure them on the silk, make the integrated circuit, the sensors, the actuators. It takes on, then, the form of almost a thin film applique that can be inserted into the body. It's flexible. It can conform to tissues inside the body to provide necessary function for different clinical use cases that we have in mind.

BLOCK: And all of that circuitry that you're describing, completely biodegrades, just breaks down, disappears?

ROGERS: Yeah. That's right. I mean, that's the challenge that we set out to address when we started this research about three years ago. For the metals, we like magnesium, it has very good conductivity. We can pattern it into forms that can be used for electrodes. And magnesium itself is a component of many multivitamins, so I think it's a material that's sensible to think about inserting into the body without adverse consequences.

For the semiconductor, we use silicon. And we like silicon because it is the material of choice for almost all commercial integrated circuits. The way that we use it, however, is in the form of ultrathin sheets and ribbons, much, much thinner than what's used commercially. And that's important because it minimizes the material load on the body. And it allows the silicon itself to dissolve in biofluids on time scales that are reasonable for these kind of implanted applications that we have in mind.

BLOCK: Have you actually implanted these disappearing devices, these transient devices in humans?

ROGERS: Not in humans. We have done it in animal models. Rats and mice. We've demonstrated efficacy, killing bacteria in-vitro, in a petri dish essentially. We've taken the same device, implanted it in animals, shown that we can operate the device wirelessly to create heating at a level that would kill bacteria. And our current work is to sort of close the loop. That is infect animals with bacteria, then use this device to kill them in-vivo. And that's a topic of ongoing research.

BLOCK: Well, it's fascinating to think about. Professor Rogers, thanks so much for talking to us about it.

ROGERS: Thank you. That's John Rogers at the University of Illinois, Urbana-Champaign. He's head of a research team that's developing transient electronic devices made of biodegradable materials.

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