Looking for thin sensor for detecting silicon wafers

[JubilationTCornpone]

Hello, all. I'm looking for a very thin sensor that I can use for detecting silicon wafers. It is to be used in a robotic end-effector for the semiconductor industry.

I had previously planned on using a thin capacitive sensor which was to be offered by a certain vendor. Since then, I've been told that this sensor might not be offered after all, so I need to start looking for alternatives.

Help?

 

You did not mention what size wafer you
are handling nor the task you will be
implementing to handle the wafers, but
I think you should be glad that you can't
use the capacitive sensors. I doubt this
type of sensor would be accurate enough
for your purposes. I think you can use
low power laser and sensor pairs to find
rough position/proximity, and since you
will probably "effecting" with a vacuum
paddle from the backside of the wafer, you
can monitor vacuum manifold pressure for
a spike indicating contact. You might want
to add an audio sensor to monitor ambient
noise for the sound of shattered wafers(g).

 

[JubilationTCornpone]

Actually, we're NOT using a vacuum paddle, and we can't use a laser sensor either, due to intellectual property considerations). That's why I'm looking for a thin capacitive sensor. We've been forced to abandon all those other solutions.