Engineering dissolving technology with silk circuits

By on October 24, 2012

The proteins composing spider silk can be repurposed for technology.

In the world of electronics, the adage “here today and gone tomorrow” couldn’t be more false. As we Internet Generation kids know, technology is built to last long after its usefulness has been exhausted. We all have one or two of the outdated, cumbersome desktop beasts from the early nineties lurking in a garage or attic back home. Some of us might even have a fairly new laptop in the trash pile under the box of a sleek new iPad. These rising heaps of electronic waste may be rendered quickly obsolete by a new breed of electronics designed to dissolve and disappear after use.
Transient electronics are made from a combination of silk and silicon and can be used in the human body and our environment. These materials are all biodegradable and so thin that they dissolve quickly in a minimal amount of water. Because the metals used in the devices are found within the body, they are not harmful when dissolved in or absorbed by the body. In test studies, silkworm cocoons and sheets of highly porous silicon have been used to make circuits with electrodes made of magnesium.

Research of this dissolving technology was conducted in a collaborative studdy by scholars at Northwestern University, the University of Illinois at Urbana-Champaign and Tufts University. Their findings were published this week in the journal “Science”.

“Historically, the field of electronics has been spectacularly successful because of devices that were stable over time,” Dr. John Rogers, a professor of engineering at the University of Illinois at Urbana-Champaign, says. “We wondered whether asking the opposite question of electronics could have interesting results.”

The silk is the main structural framework that controls the entire unit’s rate of dissolution. Biomedical engineer Fiorenzo Omenetto of Tufts University figured out a way to rearrange the proteins in silk so it could dissolve at various time intervals. The silk can then be dissolved and carefully recrystallized by researchers, allowing them to control the rate at which the silk dissolves again.

Once the dissolution of the devices was tested and verified, Omenetto and colleague Suk-Won Hwang engineered a silk implant in a mouse. The implant was designed to deliver an antibiotic to the infected mouse and then dissolve. The dissolution of the device was programmed according to its exposure to bodily fluids and then coated with an antibacterial compound to treat the mouse. The device was surgically implanted in the mouse at an infected spot; three weeks later the infection had been reduced and there were minimal traces of the silk device remaining in the mouse.
Transient technology is not only useful in biomedical work but has also been used to create a number of electronic devices:  transient transistors, diodes, wireless power coils, temperature and strain sensors, photodetectors, solar cells, radio oscillators and antennas, and digital cameras.

Dissolving electronics totally redefines planned technological obsolescence. Electronic companies, through the use of transient materials, can ensure that newer models will be purchased if older models deteriorate at after a specific amount of time. Transient materials also serve as a great solution to the build-up of electronic waste our world has seen over the past twenty years. This type of electronic would be the most green and environmentally friendly ever put on the market.

The implications of this new technology are staggering. Military devices would be made incredibly stealthy and therefore life-saving. Monitoring devices would no longer need to be retrieved. Costly and painful medical implantations would literally disappear. And can you even imagine being forced to get the newest iPhone because your old one dissolved?

Ethan Gissendaner
Staff Writer

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