We did a quick test of the infrared LED ribbons to see how well they generated blobs. For this test, we just wrapped part of the LED ribbon reel around the acrylic. In reality, you would trim the ribbon to an L-shaped length. We’re still trying to see if a U-shaped wrap, or a total-perimeter wrap, will produce better results. But wow, the blobs are great with just an L-shaped wrap! Keep in mind this test is showing a direct touch of the acrylic with a person’s fingertips. We’re exploring different compliant surfaces, such as silicone, Lexel, and Sulky Solvy, and will post our findings with them later.
[Note: The idea of using IR light with plexiglass (FTIR) is from a paper by Jeff Han (http://www.cs.nyu.edu/~jhan/ftirsense/index.html). If you are planning to sell something based on this you should probably check with him to make sure it is ok.]