I'm a little confused by this question, but I'll give it a try. All op-amps are actually ICs, so you may very well be using op amps already. Also, op amps are built up from transistors. In numbers, not counting computer memory chips, op amps might be the most used ICs, especially in anything involved with data acquisition and sensors. Op amps prepare and manipulate the signal, and often provide the drive signal into an analog-to-digital converter.
