Feeds

Bio-integrated circuitry melds man and machine

Flexible circuitry mimics skin, brain, human tissue

Secure remote control for conventional and virtual desktops

IEDM If you want to marry rigid silicon with soft, stretchy human tissue, it's best to create silicon devices that can conform, stretch, and live in harmony with living flesh.

So says University of Illinois professor John Rogers, who provided an update on his work with bio-integrated and transient electronics to the attendees of the International Electron Device Meeting (IEDM) on Monday in San Francisco.

Despite the continuing miniaturization of electronics that has enabled computers to move from the industrial few to the pervasively personal multitudes, Rogers is of the opinion that merely shrinking chips might not be the only way to move forward as we innovate ourselves into the increasingly digital future.

After all, he said, chips are rigid – and so are the devices into which they are placed. "If you think about an iPhone," he said, "it's a wonderful tool, but what if you wanted to take this kind of device functionality and wrap it around your brain?"

That "wrapping" would require a new form of brain/tissue interface than that now used by neuroscientists, who interface silicon chips with the human brain by mounting a chip on a substrate that has an array of silicon spikes of various lengths, calibrated to reach specific parts of the brain.

"You take that combined system and you use an air hammer to mount it onto the surface of the brain," Rogers explained. "Problem solved. Now you have a way to accommodate the geometry mismatch between planar and curvilinear because each one of these pins can penetrate to a different depth in the tissue."

Bio-integrated electronics

Flexible, conformable bio-integrated electronics could be used, as with this sheet of sensors, to monitor heart activity

But the problem really isn't solved all that well. "Of course there are disadvantages associated with that [technique]," he said, "because you destroy the tissue to some levels during the implantation process."

Not only is the destruction of tissue a problem, Rogers said, but there's the "more insidious" problem of the disparate mechanical properties of a silicon device and the brain itself. "Now you essentially have a shard of glass, a sharp pin of glass in a bowl of jello," he said. "And the jello is not static – it's swelling, it's de-swelling, it's rattling around in the head as you walk around."

That rattling around, he said, creates a persistent irritation between the brain and the device, and an ongoing deterioration of the connection due to that irritation.

Referring to the "shard of glass" method of brain/silicon interface, Rogers said, "I don't want to denigrate this. This has been the workhorse for neuroscience research for a couple of decades and it's likely to remain an important part of the toolkit going forward."

But it's not an ideal way to marry microelectronics with the brain – or, for that matter, with any other soft biological tissue. The trick, he said, is to create an interface that is soft, stretchable, shape-conformable, and biocompatible with living tissue.

Accomplishing that goal doesn't require dumping silicon and moving to organic polymers, graphene, carbon nanotubes, or some other material. Rogers and others explored those possibilities for a few years, but he came back to silicon.

One of the reasons that silicon proved to be the best substrate for his bio-integrated devices, he explained, is the simple fact that bendability is a function of thickness, with stiffness increasing by a factor equal to the cube of the thickness.

"Think about a [silicon] wafer with a thickness of about a millimeter," he said. "That corresponds to a bending stiffness of about 10 newton-meters. If you go from one millimeter to 10 nanometers, however, you go from 10 newton-meters to 10 femto-newton-meters because of that cubic scaling – that's 15 orders of magnitude."

In other words, when you create a sheet of silicon that thin, it's highly flexible. "It's nothing but Newtonian scaling," he said, "when you change a parameter like that, by 15 orders of magnitude, it really changes the way you think about the system."

Unfortunately, however, silicon sheets that thin are quite fragile, so they need to be bonded with a less-fragile substrate such as plastic or rubber. Fortunately, the thinner the silicon, the easier it is to bond with another substance without different thermal expansion rates of the two substances causing problems.

What's more, the silicon and its substrate will bond merely by their intermolecular van der Waals forces. No muss, no fuss.

Remote control for virtualized desktops

More from The Register

next story
Voyager 1 now EIGHTEEN LIGHT HOURS from home
Almost 20 BEEELION kilometres from Sol
Ex-Soviet engines fingered after Antares ROCKET launch BLAST
Speculation rife, but Orbital claims it's too early to tell
MEN: For pity's sake SLEEP with LOTS of WOMEN - and avoid Prostate Cancer
And, um, don't sleep with other men. If that's what worries you
Jim Beam me up, Scotty! WHISKY from SPAAACE returns to Earth
They're insured for $1m, before you thirsty folks make plans
ROGUE SAIL BOAT blocks SPACE STATION PODULE blastoff
Er, we think our ISS launch beats your fishing expedition
NASA: Spacecraft crash site FOUND ON MOON RIM
'What fun!' exlaims NASA boffin who found the LADEE
Comet Siding Spring revealed as flying molehill
Hiding from this space pimple isn't going to do humanity's reputation any good
BAE points electromagnetic projectile at US Army
Railguns for 'Future fighting vehicle'
prev story

Whitepapers

Choosing cloud Backup services
Demystify how you can address your data protection needs in your small- to medium-sized business and select the best online backup service to meet your needs.
Forging a new future with identity relationship management
Learn about ForgeRock's next generation IRM platform and how it is designed to empower CEOS's and enterprises to engage with consumers.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?
Saudi Petroleum chooses Tegile storage solution
A storage solution that addresses company growth and performance for business-critical applications of caseware archive and search along with other key operational systems.
Simplify SSL certificate management across the enterprise
Simple steps to take control of SSL across the enterprise, and recommendations for a management platform for full visibility and single-point of control for these Certificates.