You MUST collect 100 blobules without dying. HOWEVER, you don't need to do this on different levels. You can replay a level as many times as you want to collect the 100.
It is pretty easy to unlock this just by playing the game normally but in case you're having problems, there is a great work-around. You can play the safe route and keeping replaying a level that is impossible to die on or you can do what I did. I got this achievement on level 1-3, Plumbing Issues. There is one enemy in the level that is easily avoided and 33 blobules to collect. You'd just have to complete the level while collecting all of the blobules 3 times without dying.
If you keep playing until you collect 300 blobules without dying you'll unlock this too: