Biodegradable electronics here today, gone tomorrow
[1] A team of researchers has designed flexible
electronic components that can dissolve inside the body,
and in water. The components could be used to make
smart devices that disintegrate once they are no longer
[5] useful, helping to alleviate electronic waste and enabling
the development of medical implants that don’t need to
be surgically removed.
The project is led by John Rogers, a materials
scientist at the University of Illinois at Urbana-
[10] Champaign, and Fiorenzo Omenetto, a biomedical
engineer at Tufts University in Medford, Massachusetts.
The two say that after several years of work, they and
their colleagues can now make just about any kind of
dissolving, high-performance electronic or optical device.
[15] The project really took off in 2009, when the
researchers brought together Rogers’ expertise on flexible
silicon electronics and Omenetto’s tough, biocompatible
silk. The silk is made by processing and moulding
proteins from silkworm cocoons to make thin sheets
[20] that conform and stick to tissues, such as the surface
of the brain. By changing the processing conditions,
Omenetto can control how long it takes the silk proteins
to break down when wet. The researchers then placed
Roger’s silicon integrated circuits together with
[25] light-emitting diodes and other electronic devices on
Omenetto’s silk. They’ve since demonstrated numerous
devices, including brain interfaces that take very sensitive
electrical measurements, but although the devices
showed no adverse effects in early animal tests, they
[30] didn’t completely dissolve — the metals were left behind.
And having silicon floating around under the skin is not
ideal, says Omenetto.
Now, the researchers have figured out how to make
every part of the system disintegrate. Rather than using
[35] stable metals such as copper or silver for electrical
connections, they turned to magnesium. Magnesium is
conductive, but it is also very reactive — especially in
wet conditions — so isn’t often used in electronic circuits.
For dissolving electronics, however, that is an advantage.
[40] The team use magnesium to connect integrated circuits
and to form antennas and wires that allow the devices to
be powered from outside the body.
The other key is treating the silicon correctly. The
team had something of a eureka moment about the
[45] material. “You don’t think of silicon as water soluble”, he
says, because it would take 1,000 years for an average
silicon wafer to dissolve. The thin silicon membranes in
the dissolvable devices are less than 100 nanometres
thick, and dissolve at about 4.5 nanometres a day. The
[50] team can control the degradation of the devices by tuning
the properties of the silk, and by changing the thickness
of the silicon and other materials.
Biodegradable electronics here today, gone tomorrow. Disponível em: . Acesso em: 10 out. 2012. Adaptado.
All the components of the electronic circuits invented by Roger and Omenetto’s team can dissolve inside the body and in water because they are
