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Posted: October 7, 2008
IMEC makes progress with sensing, skin-like foils
(Nanowerk News) IMEC's associated laboratory at the
Ghent University, INTEC, has made the first functional optical links
embedded in a flexible substrate. The links include optical waveguides,
light sources, and detectors. With this technique, it becomes possible to
make foils that sense changes in pressure. Such sensing, skin-like foils,
could be used for monitoring irregular or moving surfaces, e.g. in robots,
pliable machinery, or as an artificial skin.
Integrated optical interconnections have the advantage that they are
insensitive to electromagnetic interference, applicable in harsh
environments, and highly sensitive. Last year, IMEC already reported
embedded optical links on rigid surfaces. The current research takes
optoelectronics one step further. Standard commercially available GaAs
photo-detectors and GaAs VCSELs (vertical-cavity surface-emitting laser)
are thinned down to 30µm. Next, they are embedded into a flexible foil of
optical transparent material and optically coupled with embedded waveguides
and out-of-plane micromirrors. The resulting structure shows good adhesion
and flexible behavior.
With this technology, IMEC is working on two types of sensors: array
waveguide sensors and optical fiber sensors. Both can be used for sensor
foils. Array waveguide sensors rely on the change in coupling between
arrays of crossing waveguides. Two layers of polymer waveguides are
separated by a thin layer of soft silicone. When no pressure is applied, no
crosstalk is detected. But when pressure is applied to the foil, the
distance between the waveguides in the separated layers decreases, and
light is transmitted from one layer to the other. This low-cost sensor is
ideally suited for high-density pressure sensors on small areas.
Optical sensing foils combine two technologies that have lately seen a
growing interest: integrated optical interconnections, and flexible,
stretchable electronics. The ambition of researchers is to create a
flexible and stretchable skin-like foil sensitive to touch, pressure, or
deformation. Such artificial skin could be used in medical and industrial
environments. To this aim, a group of European research institutes,
including IMEC, are collaborating in the 7th Framework project PHOSFOS
(Photonic Skins For Optical Sensing).
PHOSFOS will develop photonic foils based on optical fiber sensors. These
foils are targeted at applications in civil engineering and medicine. They
will, for example, continuously monitor the integrity and the behavior of
buildings, dams, bridges, roads, or tunnels. Other uses are monitoring
aircraft wings, helicopter blades, or windmill blades. They will enable
early warning of failure or anomaly. Skin-like PHOSFOS membranes will also
be used in long-term monitoring of respiration and cardiac activity, as
well as the detection of pressure points under bed-ridden patients.
IMEC is a world-leading independent research center in nanoelectronics and
nanotechnology. IMEC vzw is headquartered in Leuven, Belgium, has a sister
company in the Netherlands, IMEC-NL, offices in the US, China and Taiwan,
and representatives in Japan. Its staff of more than 1600 people includes
more than 500 industrial residents and guest researchers. In 2007, its
revenue (P&L) was EUR 244.5 million.
IMEC's More Moore research aims at semiconductor scaling towards sub-32nm
nodes. With its More than Moore research, IMEC looks into technologies for
nomadic embedded systems, wireless autonomous transducer solutions,
biomedical electronics, photovoltaics, organic electronics and GaN power
IMEC's research bridges the gap between fundamental research at
universities and technology development in industry. Its unique balance of
processing and system know-how, intellectual property portfolio,
state-of-the-art infrastructure and its strong network worldwide position
IMEC as a key partner for shaping technologies for future systems.
Further information on IMEC can be found at www.imec.be.