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Silk Implants Fight Bacterial Infection Then Vanish

Simple device made of silk and magnesium can be wirelessly triggered to fight infections using heat or drugs

2 min read
Silk Implants Fight Bacterial Infection Then Vanish
Photo: Tufts University

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A new electronic implant can fight bacterial infection inside the body and then harmlessly dissolve. The simple, passive device is made entirely of silk and magnesium, which are both benign, biocompatible materials. The device, which can be loaded with antibiotics, could be implanted inside the body during surgery and then wirelessly triggered from outside to kill bacteria using heat or by releasing drugs. Once its work is done, it would dissolve.

The idea is to make benign, functional electronics that last in the body for a finite amount of time so that no surgical retrieval is required, explains Fiorenzo Omenetto, a professor of bioengineering at Tufts University. Researchers from Omenetto’s group, together with collaborators from the Shanghai Institute of Microsystem and Information Technology in China and the University of Illinois at Urbana-Champaign, presented results on their device at the IEEE MEMS 2015 conference last week.

Several other research teams are exploring the potential of spider silk for electronics. Omenetto focuses on silkworm silk. In addition to vanishing medical implants, he wants to make silk-based consumer electronics that would degrade when needed rather than lying around in landfills. He has made graphene-and-silk-based nanosensing tattoos to detect bacteria in the mouth. And with UIUC’s John Rogers, he has previously made silk-encased dissolvable electronics that used silicon nanomembranes as the electronics substrate.

The device that the researchers presented at MEMS 2015—and recently in the journal PNAShas no silicon. It’s a very simple design: a power-receiving coil and a serpentine resistor made of magnesium are deposited on a silk film and then encapsulated in a silk pocket. Omenetto’s team gets the silk from silkworm cocoons. They’ve figured out how to fine-tune the silk’s crystallinity and other properties so that it degrades at time intervals ranging from minutes to weeks.

“You then have a little band-aid that you put under the skin,” Omenetto says. “Silk here acts like the plastic substrate, and it is medically digestive. And the magnesium on top hydrolyzes and breaks down and dissolves.”

The researchers implanted the device in the skin of mice that were infected with the Staphylococcus aureus bacteria. They wirelessly activated the device using a transmitter for two sets of ten-minute treatments. The resistor heats up, and the heat kills bacteria. After 24 hours, tissue collected from the mice was infection-free. The device fully dissolved and vanished in 15 days.

In a separate in vitro experiment, the researchers loaded a silk film with the antibiotic ampicillin and attached it, along with a magnesium heater, to a silk pocket. When they wirelessly heated the device, the silk film released the drug.

Photo: Tufts University

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Are You Ready for Workplace Brain Scanning?

Extracting and using brain data will make workers happier and more productive, backers say

11 min read
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A photo collage showing a man wearing a eeg headset while looking at a computer screen.
Nadia Radic
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Get ready: Neurotechnology is coming to the workplace. Neural sensors are now reliable and affordable enough to support commercial pilot projects that extract productivity-enhancing data from workers’ brains. These projects aren’t confined to specialized workplaces; they’re also happening in offices, factories, farms, and airports. The companies and people behind these neurotech devices are certain that they will improve our lives. But there are serious questions about whether work should be organized around certain functions of the brain, rather than the person as a whole.

To be clear, the kind of neurotech that’s currently available is nowhere close to reading minds. Sensors detect electrical activity across different areas of the brain, and the patterns in that activity can be broadly correlated with different feelings or physiological responses, such as stress, focus, or a reaction to external stimuli. These data can be exploited to make workers more efficient—and, proponents of the technology say, to make them happier. Two of the most interesting innovators in this field are the Israel-based startup InnerEye, which aims to give workers superhuman abilities, and Emotiv, a Silicon Valley neurotech company that’s bringing a brain-tracking wearable to office workers, including those working remotely.

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