LED on conductive glass (08/04/10)

I happened to get hold of some conductive-coated glass from university so I made a little demo with a surface-mount LED. The glass is Pilkington TEC™ and has a thin conductive coating on one side. I don't think it's ITO (indium-tin oxide), since it was nearly impossible to etch it off the surface to isolate two parts of the glass. I resorted to scratching it and a little bit of conc HF! The coating is very conductive - the resistance measured between two points 5cm apart was only 20Ω or so.

The LED is mounted using conductive "wire glue" which is widely available on EBay. This is nothing more than graphite in a thin glue binder. However, it results in an extremely conductive joint and is quite strong. The main electrical connections were made with self-adhesive copper tape wrapped round the glass and then painted with wire glue.

It's quite a neat demonstration to show people, because they are usually baffled by how current is conveyed to the LED!