About 30 years ago, I had a toy that was basically just a clear plastic disk
with a flexible sheet of thin plastic glued around the edges of one side,
and sandwiched between the flexible sheet and the hard, clear disk was some
sort of liquid that changed color as you manipulated it by pressing on the
plastic sheet and moved the liquid around. The liquid was supposedly
composed of "liquid crystals" and was always a rainbow of colors no matter
how much you mixed it around in there. The liquid was so touch-sensitive,
you could lay the plastic disk on your inner wrist just below the base of
your thumb, where your pulse is strong, and see the liquid change color
pulsating with your heartbeat.
The disks came in two sizes, one was about 3 inches across and one was on a
key chain and was about 3/4 inch across.
I lost them a long time ago, and have never seen them since. Unfortunately,
with the popularity of LCD (liquid crystal display) screens, searching
Google for liquid crystals is pretty much useless.
Does anyone know where I can find info about these toys, or maybe even buy