Here are some tips on building bigger biceps.

Curling big weight isn't necessarily going to make your arms grow, especially if you're not loading the biceps correctly. It's very common to experience limited muscle fibre breakdown within the bicep, even after doing many sets targeting this muscle purely because there's not enough isolation. To make the BICEP grow you must remove as much of the stress as possible on the surrounding areas, exclude help from external forces and make the BICEP move the weight whilst remaining under tension. 

Isometric Pause

At the point where you reach full flexion at the top of each rep, when doing curls you should pause for 2 seconds. At this point squeeze your biceps as hard as you can!! Follow this up with a 3-4 second eccentric. Ultimately this will make your Central Nervous System recruit more fibres within the bicep muscle and improve isolation! 

Single Preacher Curls 

Single preacher curls are very good for improving bicep isolation because you're able to push the pad into your armpit, reducing shoulder involvement. It usually means that you also have more mobility to externally rotate and make the bicep do more of the work through a fuller range of motion. Using cables for this exercise is a good idea!