Hit the spot - 2d light point localisation in flexible and stretchable planar waveguides
Sprache des Vortragstitels:
MRS Spring Meeting 2009, San Francisco, USA
Sprache des Tagungstitel:
We present different ways to tackle the problem of fabricating a flexible and large-area device that can detect the precise position of a light and/or touch signal on its surface without need for advanced patterning techniques for pixelation. Two basic approaches are presented. A large area organic photodiode with highly resistive electrodes can be used, where the position of a light spot on the surface can be traced via the drop of current over the electrode surface. As second option, a planar waveguide fabricated from the silicone elastomer PDMS doped with organic luminescent dyes can be used. Here, the dyes couple the incoming light into the waveguide mode. The signal is detected by photodiodes embedded in the waveguide in a regular pattern. The attenuation of the light in the waveguide leads to a direct distance relation between the light spot and the photodetector, thus allowing an easy recalculation of the absolute position of the light spot on the waveguide surface. Both approaches can be combined with an additional elastomer waveguide flooded with light by LEDs embedded at the edges. If this second waveguide is deformed by application of localized pressure, light is coupled out at this spot and scattered into the position sensitive device, making it a light- as well as touchpoint sensitive detector. These devices are inexpensive to build on large areas, flexible and can even be stretchable. This paves the way towards applications like large area interface tools for computers and machines, as well as artificial skin for robots.