I have an existing sensor that ties into a specified PLC. That gives
a micro amp signal. The controller's analog input is 12 bits. It's an HMI controller that was specified. Is there any type of signal conditioner that could amplify the signal to a usable range? A 16-bit card would give me enough resolution but isn't an option in this case.

 

There is a good collection of packaged instrumentation amplifiers sold by Omega here
http://www.omega.com/subsection/signal-conditioners-all.html

This article discusses user design of an op amp or instrumentation amplifier
http://www.sealevel.com/support/art...l-Conditioning-for-Accurate-Measurements.html
or
http://tinyurl.com/z39qlyv