15 sensors in series: 1x5v or 15x5v?

Hi, and thanks for the very prompt response.

You suggest the 220R is too low when using multiple FSRs; what value can you suggest?
I only have one 5v output pin (Mega2560) - the reason I suggested 15x5v from the digPins was, if one circuit works, then duplicate it 15 times to ensure success?? Here's a sketch of my current circuit:

matrixPic.jpg