MANHASSET, N.Y. European researchers said they have achieved the first functional optical links to be embedded in a flexible substrate.
The advance was reported by the Belgian research consortium IMEC's associated laboratory, INTEC, at Ghent University. IMEC claims the new technique makes it possible to construct foils that sense changes in pressure. The skin-like foils could be used for monitoring irregular or moving surfaces.
Researchers are seeking flexible, skin-like foils that are sensitive to touch, pressure or deformation. Such artificial skin could be used for medical and industrial applications.
Optical sensing foils combine two technologies: integrated optical interconnections and flexible electronics.
Last year, IMEC reported embedded optical links on rigid surfaces.
The current research takes optoelectronics one step further. Standard, commercially available GaAs photodetectors and GaAs vertical-cavity surface-emitting lasers are trimmed to 30 micrometers. Next, they are embedded into a flexible foil of optical material and optically coupled with embedded waveguides and out-of-plane micromirrors. The resulting structure shows good adhesion and flexible behavior, IMEC claimed.
IMEC is working on two types of sensors: array waveguides 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 was detected. But when pressure is applied, the distance between the waveguides in the separated layers decreases, and light is transmitted from one layer to the other.
IMEC earlier reported progress on flexible electronics after developing a process to produce ultra-thin flexible packaging for integrated circuits.
The current IMEC research is a collaborative effort by a group of European research institutes participating in the 7th Framework project, also known as PHOSFOS (Photonic skins for optical sensing).
PHOSFOS seeks to develop photonic foils based on optical fiber sensors for continuous-monitoring applications for buildings, dams, bridges, roads or tunnels.